summer project
-
Upload
deepti-rana -
Category
Documents
-
view
71 -
download
4
description
Transcript of summer project
PROJECT REPORT
on
SYNTHESIS AND CHARACTERISATIONAL STUDIES OF PORPHYRINS, METALLOPORPHYRINS AND THEIR
NANOPARTICLES
(Summer Internship May-July 2012)
BACHELOR OF TECHNOLOGY + MASTERS OF TECHNOLOGY (DUAL DEGREE COURSE)
In
NANOTECHNOLOGY
Under the guidance of:
Prof. S. M. S. Chauhan
HOD, Chemistry,
Delhi University.
Submitted by: Deepti rana, 7th Semester
B.Tech.+M.Tech(2009-14)
Enl No. A1223309036
CERTIFICATE
This is to certify that Deepti Rana is a B.Tech. + M.Tech. in Nanotechnology (Dual) Degree
course student of Amity Institute of Nanotechnology, Amity University, Noida and has
sucessfully underdone Summer Internship on the topic on “Synthesis and Characterisation
studies of Porphyrins, Metalloporphyrins and their Nanoparticles” during the period
May 2012 to July 2012 at Delhi University, North Campus.
The information submitted is true and original to the best of our knowledge.
Prof. S. M. S. Chauhan Ms Deepti Rana
HOD Chemistry, B.Tech+M.Tech (Nanotech.)
Delhi University Amity University, Noida
Declaration
I, Deepti Rana, student of B.Tech + M.Tech. in Nanotechnology (Dual), batch 2009-2014, 7th
semester, studying at Amity University hereby declare that the project training report entitled
“Synthesis and Characteisational studies of Porphyrins, Metalloporphyrins and their
Nanoparticles” is an authentic record of my own work carried out at Delhi University,
Chemistry Department, North Campus as per requirements of the Six Weeks Internship
Project for the award of degree of B.Tech + M.Tech. in Nanotech. (Dual) from Amity
Institute of Nanotechnology, Amity University, Noida, under the guidance of Prof. S. M. S.
Chauhan, HOD Chemistry, Delhi University from May-July 2012.
Deepti Rana
Enl no A1223309036
Date: 30/Oct/2012
Certified that the above statement made by the student is correct to the best of my knowledge
and belief.
Prof. S. M. S. Chauhan
HOD, Chemistry
Delhi University
Acknowledgement
It is my pleasure to be indebted to various people, who directly or indirectly contributed in
the development of this work and who influenced my thinking, behavior and acts during the
course of study.
First of all I would like to thank my guide, Prof. S M S Chauhan, H.O.D Chemistry,
Delhi University, for providing me with valuable insights and support which helped me
throughout my Internship. However, it would not have been possible without the kind support
and help of Ms Renu Guatam, PhD scholar in Chemistry, Delhi University. Furthermore my
senior lab mates and PhD scholars were also proved to be helpful and very supportive during
my internship. I would like to extend my sincere thanks to all of them.
I am highly indebted to University Science Instrumentation Centre (USIC)
Characterization Lab, Delhi University for their guidance and constant supervision as well as
for providing necessary information regarding the characterization details of project.
I would also like to heartily thank Dr. R P Singh, Director, Amity Institute of
Nanotechnology, for permitting me in achieving and completing the objectives for my
Internship.
Lastly, I would like to thank the almighty and my parents for their moral support and
my friends with whom I shared my day-to-day experience and received lots of suggestions
that improved my quality of work.
TABLE OF CONTENTS
CHAPTERS
1. Porphyrin
1.1. Porphyrin Chemistry
1.2. Properties of Porphyrins
1.2.1. Electronic Properties
1.2.2. Explanation of their Optical Absorption spectra
1.3. Biological importance of Porphyrins
1.3.1. Hemoglobin and myoglobin
1.3.2. Chlorophyll
1.3.3. Enzymes
1.3.4. Oxygenases
1.3.5. Peroxidases and Catalase
1.3.6. Cytochromes
1.4. Applications
1.5. Experimental
1.5.1. Synthesis of 5,10,15,20-tetraphenyl porphyrin [H2TPP]
1.6. Characterization
1.6.1. 1H NMR
1.6.2. UV-Vis Spectroscopy
1.7. Conclusion
1.8. References
2. Meso-substituted Symmetrical Porphyrins
2.1. Synthesis methods
2.1.1. Alder and Longo method
2.1.2. [2+2] Condensation
2.2. Application
2.3. Experimental
2.3.1. Synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’,-pentafluorophenyl) porphyrin
[F20TPP] by Alder and Longo method
2.3.2. Synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’,-pentafluorophenyl) porphyrin
[F20TPP] by [2+2] Condensation
2.3.2.1. Synthesis of 5-(pentafluorophenyl) dipyrromethane (DPM) by
Amberlyst-15
2.3.2.2. Synthesis of F20TPP by [2+2] condensation of 5-(pentafluorophenyl)
dipyrromethane
2.4. Characterisation
2.4.1. 1H NMR
2.4.2. UV-Vis Spectroscopy
2.5. Conclusion
2.6. References
3. Metalloporphyrins
3.1. Introduction
3.2. Properties
3.3. Experimental
3.3.1. Synthesis of Iron(III) 5,10,15,20-tetraphenyl porphyrin [H2TPPFe(III)Cl]
3.3.2. Synthesis of Zinc 5,10,15,20-tetraphenyl porphyrin [TPPZn]
3.3.3. Synthesis of Iron(III) 5,10,15,20-tetra (2’,3’,4’,5’,6’-pentafluorophenyl)
porphyrin [F20TPPFe(III)Cl]
3.3.4. Synthesis of Zinc 5,10,15,20-tetra)2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[F20TPPZn]
3.4. Characterization
3.4.1. UV-Vis Spectroscopy
3.5. Conclusion
3.6. References
4. Porphyrin Nanoparticles
4.1. Introduction
4.2. Properties
4.3. Application
4.4. Experimental
4.4.1. H2TPP Nanoparticles
4.4.1.1. Synthesis of H2TPP nanoparticles by Solvent Mixing Techniques
4.4.2. F20TPP Nanoparticles
4.4.2.1. Synthesis of F20TPP Nanoparticles by Sonication Technique
4.5. Characterization
4.5.1. TEM
4.5.2. UV-Vis Spectroscopy
4.6. Conclusion
4.7. References
SYNTHESIS AND
CHARACTERIZATION STUDIES OF
PORPHYRINS,
METALLOPORPHYRINS AND THEIR
NANOPARTICLES
CHAPTER 1
PORPHYRINS
Porphyrins are one of the vital chemical units essential for several life processes on the earth.
Many biological molecules function with prosthetic groups essentially made of these units.
Chlorophylls of chloroplasts which drive photosynthesis, heme as a component of
hemoglobin that transports oxygen to animal tissues and as the central unit of myoglobin
ensures the storage of oxygen - all these have active sites essentially made of porphyrin core
[1-3]. Over the years, a great deal of concerted efforts have brought to light substantial
understanding of the structure-function relationship in these natural porphyrins[4-10].
A large variety of synthetic porphyrins and their metalloderivatives were made over the years
to study the porphyrin based natural systems. The search for anti-cancer drugs, useful
catalysts, semiconductors and superconductors, electronic materials with novel properties has
also made this synthetic porphyrin chemistry a very actively probed one by chemists,
biologists and physicists alike. The synthetic meso-substituted porphyrins offer a great
advantage to study the physical and chemical properties of the porphyrin nucleus
quantitatively by a judicious choice of the substituents that may be attached on the periphery.
Metalloporphyrins are widely and intensely investigated in the area of catalysis and also as
models and mimics of enzymes lie catalase, peroxidases, P450 cytochromes or as
transmembrane electron transport agents [11-13]. They have also been used as NMR image
enhancement agents [14], Nonlinear optical materials [15] and DNA-binding or cleavage
agent [16,17].
Currently there is interest in using chelated radioactive metal isotopes as diagnostic imaging
and therapeutic agents. In that context pophyrins are excellent compounds because of their
extremely high stability constants with many metal ions.
1.1 Porphyrin Chemistry
Porphyrins are a group of organic compounds, many naturally occurring. One of the best
known porphyrins is heme, the pigment in red blood cells; heme is a cofactor of the protein
hemoglobin. Porphyrins are aromatic and obey Hückel's rule for aromaticity, possessing 4n+2
π electrons (n=4 for the shortest cyclic path) delocalized over the macrocycle. Thus porphyrin
macrocycles are highly conjugated systems. As a consequence, they typically have very
intense absorption bands in the visible region and may be deeply coloured; the
name porphyrin comes from a Greek word for purple. The parent porphyrin is porphine, and
substituted porphines are called porphyrins. The specific porphyrin in heme B is
called protoporphyrin IX and has 4 methyl, two vinyl, and two propionic acid substituents at
the indicated positions.
Porphine Heme group B of Hemeoglobin
The porphyrin macrocycle is an aromatic system consisting of four “pyrrole-type” rings
joined by four methine (meso) carbons. Although a porphyrin ring has a total of 22-π
electrons, only 18 of them participate in any one of the several delocalization pathways. Due
to the anisotropic effect from the porphyrin ring current, the shielded N-H protons appear at
very high field (-2 to -4 ppm) in the 1H-NMR spectrum, whereas the peripheral protons show
up at low field (8-10 ppm) due to the presence of the deshielding environment resulting from
the aromatic ring current [18]. In the visible absorption spectra, porphyrins usually show an
intense Soret band [19] at around 400 nm, which results from the delocalized cyclic
electronic pathway of porphyrins. Several weaker absorption bands between 450 nm and 800
nm, which are responsible for the rich colour of porphyhrins, are also observed and known as
Q bands.
Porphyrin macrocycle
Besides many synthetic and naturally occurring ones with the core structure mentioned
above, there are many biologically active systems which also have porphyrin-like structures
which are given in [2-7].
Central metal and porphyrin ligand bond nature
The nature of bonding between a central metal and the porphyrin ligand is found to be
originating essentially from the following two types of primary interactions: a-coordination
of nitrogen lone pairs directed towards the central metal atoms and π-interaction of metal pπ
or dπ orbitals with nitrogen-based π orbitals [20]. The appropriate symmetry-adapted linear
combinations of prophyrin-ligand orbitals involved in the bonding with metal orbitals are
shown in Figure 1.
Figure 1 The symmetry adapted linear combination of porphyrin-ligand orbitals involved in the
bonding with metal orbitals (a) are suitable for σ-interactions and (b) for π-interaction
In the σ-system the prophyrin is clearly a donor to the metal while in the π-system porphyrin
has the appropriate orbitals to act both as a π-donor and as a π-acceptor. The versatile
characteristics of the ubiquitous porphyrin molecules can be attributed largely to the
extensively delocalised π-system which is electronically very sensitive and tunable.
1.2 Properties of Porphyrins
They can form a dianion as well as a dication.
The porphyrin ring is generally stable under strongly acidic and basic conditions. Strong
bases, such as alkoxides can remove the two protons (pKa ~16) on the inner nitrogen atoms
of porphyrin to form a dianion.
On the other hand, the two free pyrrolenine nitrogen atoms (pKb ~9) can be easily
protonated with acids such as trifluoroacetic acid, to form a dication.
The inner protons can also be replaced by a metal. Various types of metals (e.g., Zn, Cu, Ni,
Sn) can be inserted into the porphyrin cavity by using various metal salts (Metalloporphyrins)
[21]. Demetalation of metalloporphyrins can usually be achieved by the treatment with acids,
and different types of acids are required for the removal of different types of metals. All
nitrogen atoms [22] can also be achieved in a similar way to protonation and metalation.
They have usual Planar structures; although some exceptions are possible.
Aromatic compounds such as porphyrins used to be assumed to be planar. Although previous
reported X-ray structures of simple porphyrins showed the ring to be planar, recently, there
have been tremendous numbers of nonplanar porphyrins reported in the literature [23,24].
Nonplanar porphyrins have intriguing physical and biological properties due to the distortion
of the porphyrin ring. Many different factors such as metallation, peripheral substitutions,
alkylation of the pyrrolenine nitrogen atoms, and even protonation, can distort the nominally
planar structure of the porphyrin macrocyle.
Highly conjugated systems, thus are coloured compounds.
Due to the high conjugation of the porphyrin ring, its band gap reduces and comes in the
region of visible range imparting the ring its usual purple colour.
1.2.1 Electronic properties
The electronic heart of a porphyrin is the inner 16-membered ring with 18-π electrons. The
ring is structured with basic fourfold symmetry, including four nitrogen atoms directed
towards the center. The optical absorptions of porphyrin are determined essentially by the
nelectrons on the porphyrin ring, with only minor perturbation from the electrons of the
central substituents.
The optical absorption spectra is an important spectral phenomenon to distinguish between
the free-base porphyrins and their metalloderivatives. The spectrum changes from four-
banded to a two-banded spectrum on metallation. This dramatic effect is attributed to the
enhancing of the D2h symmetry of the free-base porphyrin to D4h on metallation [25].
Majority of metal-free porphyrins shows very characteristic absorption, which consist of two
sets of bands in the ranges of 400-450 nm and 550-700 nm. The first sets of bands are called
the B band or Soret band (strongly allowed) and the lower energy set are the Q bands (quasi-
allowed).
Figure 2 Electronic absorption spectra of (a) free-base porphyrin and (b) its metalloderivative.
1.2.2 Explanation of its Optical Absorption spectra
The Q bands of free-base porphyrins are a set of four absorptions arising from HOMO to π*
transition. Of these, the first set of two lines is x-component of Q while the second set is its y-
component. Both these Qx and Qy components are composed of two types of vibrational
excitations too, the lower energy one being Q(0,0) and the higher energy one Q(1,0). Thus
the four lines in the set are Q,(0,0), Q,(1,0), Qy(0,0) and Qy(1,0) in the increasing order of
energy.
On metallation, the spectrum shows an intense B (Soret) band at 420 nm and two weaker Q
bands at 550-600 nm [26,27]. These spectral absorptions arise from π-π* transitions of the
aromatic porphyrin ligand.
The widely accepted model to fit this spectrum, the four-orbital model, treats the porphyrin as
a cyclic polyene and emphasizes the transition between the two highest filled bonding
molecular orbital levels, a1u, a2u and the lowest empty doubly degenerate antibonding
molecular orbital levels eg*. The allowed transitions, a1u eg* and a2u eg* are assumed to
be degenerate in energy. As a consequence, the states undergo configuration interaction and
give rise to new states. The resulting spectrum shows a high energy band B in which the
transition dipoles add and a low-energy band Q in which the transition dipoles cancel. The
two Q bands are vibronic components of the same transition [28].
1.3 Biological importance of Porphyrins
Metal complexes of porphyrins and related compounds are important prosthetic groups that
assemble to form a wide variety of proteins and enzymes working as redox and
rearrangement catalysts [29]. The nature being a master designer, has chosen and retained the
best choice of molecular assemblies in living systems to carry out very specifically the
functions they are intended for and also to achieve them with the maximum efficiency.
A large number of naturally occurring porphyrin have been isolated and characterized. Of
these protoporphyrins are the most abundant and widely characterized ones. It is found in
hemoglobin, myoglobin, heme enzymes and most of the cytochromes [5].
The biological and chemical importance of metalloporphyrins has brought to focus intense
interest in the nature of the metal ligand linkages in such complexes as well as all the
physicochemical properties of the macrocycles. The macrocycle has the ability to function as
a reservoir of electrons and control the reactivity at the axial position of metal, which usually
serves as a catalytic site in heme enzyme. Because of their ubiquitousness and the variety of
their natural functions, heme proteins have been investigated on multi- and interdisciplinary
levels. These proteins all containing an iron porphyrin as the prosthetic group, are responsible
for oxygen transport and storage (hemoglobin and myoglobin) [30], electron transport
(cytochromes) [31], oxygen reduction (cytochrome oxidase), hydrogen peroxide utilization
and destruction (peroxidases and catalases), and hydrocarbon oxidation (cytochrome, P.450)
[32].
Also the various functions of heme proteins in the transport, storage and reactions with
dioxygen are made possible by different and selective interactions of diverse proteins with
the heme groups [10]. These differences are brought about largely by the axial ligands
provided by ancillary groups of the protein and from the nature of the pockets on either side
of the porphyrin. Important porphyrin based natural systems are the hemoglobin, myoglobin,
chlorophyll, heme enzymes and the cytochromes.
1.3.1 Hemoglobin and myoglobin
Hemoglobin and myoglobin are high molecular weight protein systems containing iron(II)
protoporphyrin IX units. They are responsible for oxygen transport and storage in higher
animals [9]. Hemoglobin transport dioxygen from its source to the site of use inside the
muscle cells. There the oxygen is transferred to myoglobin for use in respiration. Myoglobin
which is responsible for storing oxygen in cells, has high affinity for the dioxygen even at
low partial pressure but in lungs, hemoglobin takes up high amount of oxygen at high partial
pressure. This special property of hemoglobin is attributed to the 'cooperative effect" caused
by the decrement in size of Fe2+ in central hole due to spin change (from high spin to low
spin) on dioxygen complexation [33,34].
The iron in hemoglobin and myoglobin is in the ferrous state and has to have an N-base
(histidine) coordinated to the metal from one of the sides of the plane to have dioxygen bound
at the vacant sixth coordination site. The oxidized form of iron, i.e., ferric state, called
metmyoglobin and methemoglobin will not bind oxygen. The free heme is immediately
oxidized in the presence of oxygen and water and thus renders useless for O2 transport.
Myoglobin exhibits greater affinity of O2 than hemoglobin and it is largely converted to
oxymyoglobin even at low O2 concentration in order to affect the transport of O2 at the cell
[9]. Upon the oxygenation of hemoglobin, two of the heme groups move about 100 pm
towards each other while two others separate by about 700 pm due to the action of protein
envelope. The net result of this combined movement is that hemoglobin can exhibit relatively
low affinity for binding the fit one or two oxygen molecules. But once they are bound, the
binding of subsequent O2 molecule is greatly enhanced. Conversely the loss of one oxygen
molecule from fully oxygenated hemoglobin causes the rest to dissociate more readily when
the oxygen pressure is decreased [35].
1.3.2 Chlorophyll
Chlorophyll is the green colouring matter of leaves and green stems, and its presence is
essential for photosynthesis. In green plants it is the chlorophyll which absorbs the light
energy. Chlorophyll is basically magnesium derivative of porphyrins and some slight
structural changes in porphyrin moiety results in different classes of chlorophyll with slight
difference in photocatalytic properties [5]. All of the chlorophylls absorb light very intensely
particularly at relatively long wavelength regions [36]. The light energy absorbed by a
chlorophyll molecule become delocalised and spread throughout the entire electronic
structure of the excited molecule.
The photosynthetic pigments in the chloroplasts of plants consists of two functional units
namely photo system I and photo system II [37]. Photo system I contain chlorophyll, p-
carotene and a single molecule of P-700, a specialised chlorophyll a which serves as an
energy trap. Photo system II has a characteristic reactive centre namely P-680 a specialized
chlorophyll-protein complex. Photo system I absorbs light at longer wavelength. Photo
system II is activated by shorter wavelength, i.e., 670 nm and below and it is responsible for
oxygen evolution.
Both the photo systems contain chlorophyll a and chlorophyll b. In photo system I, the ratio
of chlorophyll a to chlorophyll b is higher than in photo system II [5]. These two photo
systems must cooperate to yield maximum result in photosynthesis.
1.3.3 Enzymes
Enzymes are biological catalysts that govern, initiate and control biological reactivity
important for the life processes. They are produced by the living organism and are usually
present in only very small amounts in the various cells. All known enzymes are proteins and
some contain non-protein moieties termed prosthetic groups that are essential for the
manifestation of catalytic activities [4,5,9]. In several natural enzymes, metalloporphyrins
constitute these prosthetic groups.
1.3.4 Oxygenases
There are various enzymatic reactions in which one or both atoms of O2 are directly inserted
into the organic substrate molecule to yield hydroxyl groups. Enzymes catalyzing such
reactions are called oxygenase, of which there are two classes - the dioxygenase catalyzes
insertion of both atoms of the O2 molecules into the organic substrate, whereas the
monooxygenase inserts only one [4].
The most important monooxygenase is cytochrome P-450 found in the microsomes of liver
cells [38]. Cytochrome P-450 contains protoheme. The CO derivative of its reduced form
absorbs maximally at 450 nm, hence the name cytochrome P-450. During the enzyme
reaction the ferric P-450 first combines with a substrate followed by a one electron reduction
to form a ferrous P-450 substrate complex. The reduced Fe(II) form of P-450 reacts with
molecular O2 in such a way that one of the O-atoms is reduced to water and the other is
introduced into the organic substrate.
Cytochrome P-450 enzymes catalyze hydroxylation of many different kinds of substrates
including steroids, fatty acids, certain amino acids etc and thus making them more water-
soluble. They also promote hydroxylation of various drugs.
1.3.5 Peroxidases and Catalase
Peroxidases are enzymes catalyzing the oxidation of a variety of organic and inorganic
compounds. Peroxidases obtained from plants contain hemine groups. The different types of
peroxidases are horseradish peroxidase, myloperoxidase, chloroperoxidase etc [8].
Catalase is also a heme enzyme which catalyze the dismutation of H2O2 generated during
various life processes. Catalase is made up of four identical sub-units each containing one
heme group. The axial metal sites appear to be occupied by water and an amino acid residue.
1.3.6 The Cytochromes
The cytochromes are electron transferring proteins, containing iron porphyrin, found in
aerobic cells. Some cytochromes found in endoplasmic reticulam, play a role in specialized
hydroxylation reactions [30]. All cytochromes undergo reversible Fe(III)-Fe(II) valency
changes during their catalytic cycles. In almost all the cytochromes both the fifth and sixth
positions of the iron are occupied by the R groups of specific amino acid residue of the
proteins [39]. Therefore, these cytochromes cannot bind with ligands like O2, CO or CN-. An
important exception is cytochrome oxidase that normally binds O2 in its biological function.
The iron protoporphyrin group of cytochrome c is covalently linked to the protein by
thioether bridges between the prophyrin ring and two cysteine residue in the peptide chain
whereas in other cytochromes the porphyrin ring is non-covalently bound. Cytochrome c is
the only common heme moiety in which the heme is bound to the protein by a covalent
linkage.
1.4 Applications
Porphyrins and related macrocycles provide an extremely versatile synthetic base for a
variety of material applications. The broadly defined porphyrin research area is one of the
most exciting, stimulating and rewarding for scientists in the field of chemistry, physics,
biology and medicine. The beautifully constructed porphyrinoid ligand, perfected over the
course of evolution, provides the chromophore for a multitude of iron, magnesium, cobalt
and nickel complexes which are primary metabolites and without which life itself could not
be maintained. The field is spreading rapidly in every direction across the whole spectrum
[40].
Diverse applications of porphyrins and metalloporphyrins to materials chemistry have been
developed over the past decade, both for their optical properties and their applications as
sensors. Notably, porphyrins and metalloporphyrins have found applications as field-
responsive materials, particularly for optoelectronic applications, including mesomorphic
materials and optical-limiting coatings. For example, the facile substitution of the periphery
of various porphyrins has generated a series of unusual liquid crystalline materials. The
porphyrin ligand serves as a platform on which one can erect desirable molecular and
materials properties.
The nonlinear optical properties of these materials are of special interest, in part for energy
transfer with molecular control, and in part for potential application in optical
communications, data storage and electro optical signal processing. The stability of mono-
and di-cation porphyrin π-radicals makes these systems especially interesting for
photoionization processes. Porphyrins and metalloporphyrins can also be used as nonlinear
optical materials. They have desirable properties for use in optoelectronics. They have greater
thermal stability and their extended π-conjugated macrocycle ring give large nonlinear optical
effects and subtle variation in their physical properties can be made easily through chemical
modification of their periphery [41-45].
They also play key roles in adsorbing light energy over a wide spectral range and converting
it into the highly directional transfer of electrons [46-50]. It is a marvellous but highly
complex process that has inspired considerable interest in the synthesis of porphyrin arrays. A
bio mimetic approach to the photosynthetic apparatus may also lead to applications of similar
systems as optoelectronic devices.
Because of their inherent stability, unique optical properties, and synthetic versatility,
porphyrins and metalloporphyrins are excellent candidates for a variety of sensing-materials
applications. Research in this area has focussed on incorporation of synthetic porphyrins and
metalloporphyrins into a variety of material matrices, such as polymers, glasses and films [3].
The unique spectral characteristics and synthetic versatility of porphyrins allow a variety of
sensing applications. They are also used in the detection of organic vapours and ionic species
in solution.
Photochemical reduction of water utilizes only a limited portion of sun ray. Porphyrins,
whose absorption spectra over an appreciable portion of the spectrum of sunlight, are of great
interest in this respect. Also metalloporphyrins exhibit very high photochemical stability [51].
Large attempts are also made to utilize the photochemical properties of metalloporphyrins in
organic synthesis.
Metalloporphyrins of aluminium, zinc, manganese, cobalt and rhodium complexes have been
demonstrated to serve as excellent initiators for controlled anionic and free radical
polymerizations [52]. The discovery of these metalloporphyrins-based initiators has led to
significant contributions to the progress of precision macromolecular synthesis via "living
polymerization" (i.e., growth pattern of the macromolecule can be viewed as analogous to the
growth of a biological organism) [53-55].
The worldwide approval of Photofibrin [a purified version of Hematoporphyrin derivative
(HpD); a complex mixture of dimers and oligomers in which porphyrin units are joined by
ether, ester and carbon-carbon bonds] for the treatment of various types of cancers has
created enormous interest among physicians, chemists, biologists and physicists [56,57].
During the early and mid 1970s, several groups together has realized that together HpD and
light (Photo dynamic therapy) had a potential capability for tumor destruction. This is now
one of the accepted modalities for the treatment of cancer [58,59].
In addition to its use for cancer treatment, Photo dynamic therapy has also shown a potential
for applications in other areas: They have found applications in molecular recognition, boron
neutron capture therapy, virus destruction, DNA cleavage, data storage, nonlinear optics and
electrochromism treatment of aged-related macular degeneration, Psoriasis, bone marrow
purging, arthritis and purification of blood infected with various viruses including HIV.
Due to their selective localization in tumor cells, synthetic tetrapyrrole pigments have
tremendous applications in PDT (photodynamic therapy) and BNCT (boron neutron capture
therapy) [18]. PDT and BNCT are both binary cancer therapies and their side effects are
limited. PDT involves the irradiation of a photosensitizer with light of a specific wavelength,
which is absorbed by the photosensitizer and subsequently causes the excitation of the
photosensitizer to its excited singlet state, then through intersystem crossing, to reach to its
excited triplet state. The resulting excitation energy is absorbed by the triplet ground state of
dioxygen (found in all living cells) and the highly toxic singlet dioxygen (1O2) is generated;
this kills the tumor cells. BNCT involves the capture of thermal neutrons by boron-10 nuclei,
which have been selectively delivered to tumor cells. The captured neutron releases 7Li and 4He nuclei with kinetic energy (~ 2.4 Mev). These two particles are extremely cytotoxic but
can only travel a distance of about one cell diameter in tissues, thus it can selectively kill the
tumor cell containing it.
At present, all the photosensitizers in clinical trials are based on tetrapyrroles (porphyrins,
chlorins, bacteriochlorins and pthalocynanines), and it seems that porphyrin in general will
show continued interest in the exiting area of photodynamic therapy.
Porphyrins and metalloporphyrins are also ideal model compounds for studying light
harvesting, energy and electron transfer, and multi electron redox catalysis [19]. Porphyrin-
based multi porphyrin arrays and molecular wires have received much interest. In these
model systems, it is important to know how individual molecules within arrays communicate
with each other. So far, factors such as distance, orientation and geometry have been
recognized to be important factors to control this intercommunication.
1.5 Experimental
1.5.1 Synthesis of 5,10,15,20-tetraphenyl porhyrin [H2TPP]
A 500 ml three neck round bottom flask, equipped with dropping funnel and a condenser was
charged with propionic acid (250 ml). The propionic acid was brought to reflux and
benzaldehyde (5.3 g, 0.05 mole) and freshly distilled pyrrole (3.35 g, 0.05 mole) were
simultaneously added to refluxing propionic acid and the refluxing was continued for 30
minutes. The reaction mixture was left at room temperature over night. The glistering purple
crystals were filtered off, washed with water and the mixture was refluxed for 3 hours. The
hot solution was filtered under suction through a sintered glass funnel containing alumina (15
g), which had a filter paper on top of it. The alumina was thoroughly washed with
Dichloromethane (100 ml). The combined filterate was concentrated to about 20 ml and
methanol (10 ml) was added. The mixture was cooled and the resulting purple crystals were
filtered to give 5,10,15,20-tetraphenyl porphyrin [H2TPP].
1.6 Characterisation:
1.6.1 1H NMR spectroscopy
1H NMR spectrum of H2TPP
1H NMR (CDCl3) δ ppm: 8.85 (s, 8H, β-pyrrolic-H), 8.23 (m, 8H, o-phenyl H), 7.76 (m, 12H,
m- & p- phenyl H), -2.77 (brs, 2H, internal NH).
1.6.2 UV-Vis spectrum
UV-Vis spectrum of H2TPP in CHCl3
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 417.90 (1.77), 515.00 (0.11), 549.92 (0.05),
588.27(0.04), 647.22 (0.04).
1.7 Conclusion
Due to the various uses in natural and synthetic systems discussed above we have synthesized
Tetraphenyl porphyrin [H2TPP] which was purple in colour and characterized this sample
through H1 NMR and UV-Vis spectra.
1.8 References
[1] J W Buchler, "The Porphyrins" D Dolphin (Ed), Academic, New York, Part A,
Structure and Synthesis 1978,1.
[2] D Ostfeld, M Tsutsui. Novel metalloporphyrins. Syntheses and implications. Acc Chem
Res., 1974,7(2),52-58.
[3] O A Golubchikov, B D Berezin. Applied Aspects of the Chemistry of the Porphyrins.
Russ Chem Rev.,1986,55(8),1361-1389.
[4] O Hayashi, "The Enzymes" P Boyer, H Lardy, K Myrback (Eds), Academic Press, New
York, 1963,8.
[5] A L Lehinger, "Biochemistry", Kalyani Publishers, New Delhi, 1978.
[6] E L Smith, R L Hill, I R Lehman, R J Lef Kowitz, P Handler, A White,"Principles of
Biochemistry- General Aspects", McGraw-Hill Inc, Singapore, 1983.
[7] T S Mashiko, "Comprehensive Coordination Chemistry", Geoffery and Wilkinson
(Eds), Pergamon Press, Oxford, 1987,2.
[8] G I Likhtenshtein, "Chemical Physics of Redox Metalloenzyme Catalysis",Springer-
Verlag, Berlin, 1988.
[9] J E Huheey, E A Keiter, R L Keiter, "Inorganic Chemistry - Principles of Structure
and Reactivity", Harper Collins College Publishers, New York, 1993.
[10] J P Collman. Functional Analogs of Heme Protein Active Sites. Inorg
Chem.,1997,36(23),5145-5155.
[11] O A Golubchikov, B D Berezin. Applied Aspects of the Chemistry of the Porphyrins.
Russ Chem Rev., 1986,55(8),768-785.
[12] B Meunier. Metalloporphyrins as versatile catalysts for oxidation reactions and
oxidative DNA cleavage. Chem Rev., 1992,92(6),1411-1456.
[13] V V Borovkov, R P Evstigneeva, L N Strekova, E I Fillippovich . Porphyrin–quinone
compounds as synthetic models of the reaction centre in photosynthesis. Russ Chem
Rev.,1989,58(6),602-619.
[14] K E Keller, N Foster. Relaxation enhancement of water protons by manganese(III)
porphyrins: influence of porphyrin aggregation. Inorg Chem., 1992,31(8),1353-1359.
[15] K S Suslick, C T Chen, G R Meredith, L T Cheng. Push-pull porphyrins as nonlinear
optical materials. J Am Chem Soc., 1992,114(17),6928-6930.
[16] L G Marzilli. Medical aspects of DNA-porphyrin interactions. New J
Chem.,1990,14,409-420.
[17] N E Mukundan, G Petho, D W Dixon, L G Marzilli. DNA-tentacle porphyrin
interactions: AT over GC selectivity exhibited by an outside binding self-stacking
porphyrin. Inorg Chem., 1995,34(14), 3677-3687.
[18] M G H Vicente. Porphyrin-based sensitizers in the detection and treatment of
cancer recent progress. Curr Med Chem–Anti Cancer Agents.,2001,1,175-194. (b) V I
Bregadze, I B Sivaev, D Gabel, D J Wohrle. Polyhedral boron derivatives of porphyrins
and phthalocyanines. Porphyrins Phthalocyanines.,2001,5(11),767-781.
[19] M S Choi, T Yamazaki, I Yamazaki, T Aida. Bioinspired Molecular Design of
Light-Harvesting Multiporphyrin Arrays. Angew Chem Int Ed., 2003,43(2),150-158.
(b) J P Collman, P S Wagenknecht, J E Hutchison. Molecular Catalysts for
Multielectron Redox Reactions of Small Molecules: The “Cofacial
Metallodiporphyrin” Approach. Angew Chem Int Ed Engl., 1994,33(15-16),1537-
1554. (c) K M Kadish, K M Smith, R Guilard. “The Porphyrin Handbook”, (Ed)
Academic Press, San Diego, CA, 2000,3,347.
[20] K Tatsurni, R Hoffinann. Metalloporphyrins with unusual geometries. 1. Mono-, di-,
triatom-bridged porphyrin dimmers. J Am Chem Soc., 1981,103(12),3328-3341.
[21] M G H Vicente, K M Smith. Porphyrins and derivatives: Synthetic strategies and
reactivity profiles. Curr Org Chem., 2000,4,139-174.
[22] (a) P Rothemund. Formation of Porphyrins from pyrrole and aldehydes. J Am Chem
Soc., 1935,57(10),2010-2011. (b) G P Arsenault, E Bullock, S F MacDonald.
Pyrromethanes and Porphyrins Therefrom. J Am Chem Soc., 1960,82(16),4384-4389. (c)
L T Nguyen, M O Senge, K M Smith. Simple Methodology for Syntheses of Porphyrins
Possessing Multiple Peripheral Substituents with an Element of Symmetry. J Org
Chem., 1996,61(3),998-1003.
[23] A D Adler, F R Longo, J D Finarelli, J Goldmacher, J Assour, L Korsakoff. A
simplified synthesis for meso-tetraphenylporphine. J Org Chem., 1967,32(2),476-476.
[24] J S Lindsey, I C Schreiman, H C Hsu, p c Kearney, A M Marguerettaz. Rothemund and
Adler-Longo reactions revisited: synthesis of tetraphenylporphyrins under equilibrium
conditions. J Org Chem., 1987,52(5),827-836.
[25] M Gouterman. Study of the effects of substitution on the absorption spectra of
poiphin. J Chem Phys.,1959,30,1139-1161.
[26] M Gouterman, "The Porphyrins", D Dolphin (Ed) Academic New York, Part A,
Physical Chemistry, 1978,111.
[27] L J Boucher. Manganese porphyrin complexes. Coord Chem Rev.,1972,7(3),289-329.
[28] M Zerner, M Goutennan. Porphyrins. Theoret Chim Acta.,1966,4(1),44-63.
[29] R A Pasternack, A Ghetto, P Pagano, E J Gibbs. Self-assembly of porphyrins on
nucleic acids and polypeptides. J Am Chem Soc., 1991,113(20), 7799-7800.
[30] F S Mathews. The structure, function and evolution of cytochromes. Prog Biophys
Mol Biol.,1985,45(1),1-56.
[31] Y Hatefi.The mitochondrial electron transport and oxidative phosphorylation
system. Ann Rev Biochem.,1985,54,1015-1069.
[32] J L Hoard, "Hemes and Hemoproteins", B Chance (Ed), Academic Press, New York
1966.
[33] W R Scheidt, C A Reed. Spin-state/stereochemical relationships in iron porphyrins:
implications for the hemoproteins. Chem Rev.,1981,81(6),543-555.
[34] M S Perutz. Stereochemistry of cooperative effects in
haemoglobin. Nature.,1970,228,726-734.
[35] H H Seliger, W D McElory, “Light; Physical and Biological Action”, Academic Press,
New York, 1965.
[36] K Saner. Photosynthesis-The Light Reactions. Annu Rev Phy Chem.,1979,30,155-178.
[37] K E White, M J Coon. Oxygen Activation by Cytochrome P-4501. Annu Rev
Biochem.,1980,49,315-356.
[38]T Takano, B L Trus, N Mandel, G Mandel, O B Kallai, R Swanson, R F Dickerson.
Tuna cytochrome c at 2.0 A resolution II Ferrocytochrome structure analysis. J Biol
Chem.,1977,252,776.
[39] J H Chou, M E Kosal, H S Nalwa, N A Rakow, K S Suslick, "The Porphyrin
Handbook", K M Kadish, K M Smith, R Guillard (Eds),Academic Press, New York, 2000,3.
[40] H S Nalwa, "Nonlinear Optics in Organic Molecular and Polymeric Materials", S
Miyata (Eds) CRC Press, Boca Raton, FL, 1997,61,1.
[41] H S Nalwa, "Handbook of Organic Conductive Molecules and Polymers", H S
Nalwa (Ed) John Wiley & Sons, Chichester, 1997,1-4,261.
[42] H S Nalwa, J S Shirk, "Pthalocyanines: Properties and Applications", C C Leznoff, A
B P Lever (Eds), 1996,4,79.
[43] H S Nalwa. Organic Materials for Third-Order Nonlinear Optics. Adv
Mater.,1993,5,341-358.
[44] H S Nalwa. Organometallic materials for nonlinear optics. Appl Organometal
Chem.,1991,5,349-377.
[45] D S Chemla, J Zyss, "Nonlinear Optical Properties of Organic Molecules and
Crystals", Academic Press, Orlando, 1987.
[46] R H Pearlstein. Structure and exciton effects in photosynthesis. New Compr
Biochem.,1987,15,299-317.
[47] G R Fleming, J L Martin, J Breton. Rate of primary electron transfer in
photosynthetic reaction centers and their mechanistic implications.
Nature.,1988,333,190-192.
[48] M L Paddock, S H Rongey, G Feher, M Y Okamura. Pathway of Proton Transfer in
Bacterial Reaction Centers: Replacement of Glu 212 in the L Subunit by Glutamine
Inhibits Quinone (QB) Turnover. Proc Natl Acad Sci USA.,1989,86,6602-6606.
[49] G Feher, J P Allen, M Y Okamura, D C Rees. Structure and function of bacterial
photosynthetic reaction centres. Nature.,1989,339,111-116.
[50] D Holten, C Kirmarier. Primary photochemistry of reaction centers from
photosyntheic purple bacteria. Photosynth.,1987,13,225-260.
[51] A E Baron, J D S Danielson, M Gouterrnan, J R Wan, J B Callis. Submillisecond
response times of oxygen‐quenched luminescent coatings. Rev Sci Instrum.,1993,64,3394-
3402.
[52] D Mansuy. Activation of alkanes—the biomimetic approach. Coord Chem
Rev.,1993,125,129-141.
[53] T Aida, S Inoue. Metalloporphyrins as Initiators for Living and Immortal
Polymerizations. Acc Chem Res., 1996,29(1),39-48.
[54] M Szwarc, M Levy, K Milkfish. Polymerization initiated by electron transfer to
monomer. A new method of formation of Block Polymers. J Am Chem Soc.,
1956,78(11),2656-2657.
[55] T Aida. Living and immortal polymerizations. Prog Polym Sci.,1994,19(3),469-528.
[56] S Inoue, T Aida, "New Method for Polymer Synthesis", W J Mijs (Ed), Plenum, New
York 1992;33.
[57] J S McCaughan Jr. Photodynamic therapy of endobronchial and esophageal tumors:
an overview. J Clin Laser Med Surg.,1996,14(5),223-233.
[58] H Kato, T Okunaka, H Shimatani. Photodynamic therapy for early stage
bronchogenic carcinoma. J Clin Laser Med Surg.,1996,14(5),235-238.
[59] T J Dougherty. A brief history of clinical photodynamic therapy development.J Clin
Laser Med Surg.,1996,14,219-221.
CHAPTER 2
MESO SUBSTITUTED
PORPHYRINS
Meso-substituted porphyrins bearing specific patterns of functional groups are valuable
components in the synthesis of porphyrin-based biomimetic systems and crucial building
blocks for applications in material chemistry. With regard to possible types of meso-
substituted porphyrins, the most widely studied synthetic porphyrin group encompasses the
symmetrical 5,10,15,20-tetraarylporphyrins like 5,10,15,20-tetraphenylporphyrin (H2TPP)
(A4 -porphyrin 1) [1]. Additionally, symmetrical trans-substituted porphyrins (trans-A2 2 or
trans-A2B2 porphyrins 4) have recently found much use due to their simple synthesis. Less
symmetrical representatives of the meso substituted porphyrin family have been studied only
infrequently based on the absence (e.g. for mono-substituted porphyrins) or complexity (e.g.
for ABCD-porphyrins) of the necessary synthesis (Scheme 2.1).
Scheme 2.1 Meso Substituted Porphyrins
2.1 Synthesis methods
In the past 100 years, porphyrin syntheses have been developed dramatically [2]. Today,
virtually any porphyrin can be synthesized from known synthetic methodology. For example,
tetramerization of pyrroles, [3 + 1] condensation and [2 + 2] condensation are common
methodologies [3]. Tetraarylporphyrins are synthetic porphyrins and have various
applications.
2.1.1 Alder and Longo method
A simple way to obtain symmetrical porphyrins (such as the tetraarylporphyrins) is the acid-
catalyzed condensation reaction of pyrrole with specific aldehyde, followed by oxidation of
the resulting colorless porphyrinogen. This procedure, originally developed by Rothemund
and Menotti [4], has been refined by Adler and Longo [5]. It generally gives around 20%
yields for tetraarylporphyrins (Scheme 2.2). Despite the modest yields, the relative simplicity
of this method has made it well suited for preparation of large amounts of tetraarylporphyrins
(i.e., >1 g of porphyrin). Later, the Lindsey group developed higher yielding and milder
reaction conditions by using a Lewis acid (TFA or BF3) as the catalyst [6]. Subsequently,
Lindsey’s group also developed higher concentration conditions (0.1-0.3 mol L-1). Despite the
slightly lower yields, this improved synthesis is more practical for larger scale preparations of
tetraarylporpyrins. Also, the Lindsey method has the advantage that it can be used to prepare
porphyrins that required the use of acid-unstable aldehydes not generally employed under
Adler-Longo conditions.
Scheme 2.2 Reaction conditions: propionic acid, reflux.
The yields are reduced due to the formation of oligomers and this call for stringent
purification methods to remove the by-products.
2.1.2 [2+2] Condensation Method
Meso or 5-substituted dipyrromethanes are important precursors for the synthesis of meso -
substituted porphyrins by [2+2] condensation. These are used as key building blocks in the
synthesis of linear porphyrin arrays.
Synthesis of meso-substituted dipyrromethanes
The condensation of pyrrole with benzaldehyde in the presence of various cation exchange
resins afforded very good yields of meso-phenyldipyrromethane. This resin is of
macroreticular type, having a styrene divinylbenzene co-polymer matrix (15–17%
crosslinking) and the exchange capacity is in the range of 4.5–4.7 mequiv./g.
Dipyrromethanes were prepared by condensation of substituted aromatic aldehydes in neat
excess pyrrole (1:20). Most of the dipyrromethanes were readily crystallized after removal of
pyrrole. The use of macroporous cation exchange resins has the advantages of controlled
acidity due to site isolation of sulphonic acid groups, high selectivity and purity of the
product due to trace side reactions and easy work-up procedures, which was evidently proven
by the reduction of oligomer formation and the production of excellent yields of meso-
substituted dipyrromethanes in pure forms. This refined process enabled the straightforward
preparation of multi-gram batches of 5-substituted dipyrromethanes.
Scheme 2.3 Synthesis of meso substituted dipyrromethane.
A facile efficient synthetic strategy for preparing 5-substituted dipyrromethanes in excellent
yields using cation exchange resins as heterogeneous acid catalysts (Scheme 2.3). These
dipyrromethanes are subsequently transformed to symmetrical and mixed porphyrins by
[2+2] condensation.
These cation exchange resins are the functional resins with a styrene divinylbenzene
copolymer matrix having sulfonic acid groups. Macroporous (or macroreticular) functional
resins (present on the market mostly as polystyrene crosslinked with divinylbenzene) are
isotropic materials formed by chemically interconnected polymer chains, normally insoluble
in any conceivable solvent. Each resin particle can be viewed as a mini reactor filled with a
solution of functional polymer chains with pendant arms bearing sulfonic acid groups [7].
Functional synthetic cation exchange resins serve as efficient industrial heterogeneous
catalysts, potentially useful in the area of fine chemical synthesis. They offer an environment
for the catalytic reaction quite different from that of a free solution or the surface of
conventional heterogeneous catalysts based on inorganic supports. The mechanism of ion
exchanger catalysed reaction in a non-aqueous environment is similar to that operating for
conventional heterogeneous catalysts (adsorption–surface reaction–desorption). An important
consequence of the catalysis being a multiplet of sulfonic acid groups is that it shows more
than a proportional dependence of the reaction rate on the concentration of acidic centres. In
this connection, the environment of a catalytic site embedded in the polymer network can
almost be considered as a micro reactor.
Formation of symmetrical meso-substituted porphyrins
The ‘2+2 synthesis’ using dipyrromethanes as intermediates, forms the backbone of the
building block approach towards the synthesis of porphyrins. Cation exchange resins has
been used as acid catalysts in the preparation of symmetrical and mixed porphyrins
incorporating various functional groups from aryldipyrromethanes (Scheme 2.4). Aryl
dipyrromethanes (A) with aromatic aldehydes give rise to porphyrinogens, which
subsequently get oxidized to the corresponding meso-substituted porphyrins (B) by means of
p-chloranil.
Scheme 2.4 Synthesis of symmetrical meso substituted porphyrin by [2+2] condensation
2.2 Application
Meso-substituted asymmetric porphyrins (A3B) have recently found specific biomedical
applications, particularly in the field of detection and treatment of neoplastic tissue (PDT)
and also labeling and analysis of nucleic acids [8a]. Not only have they found use in the
medicinal field, but they also display unique properties and find application in several,
optoelectronics, catalysis, biomimetic and material chemistry [8b]. The availability of
suitable building blocks through synthetic methodologies that have the flexibility for
structural modification is closely tied to the level of architectural sophistication achieved in
such systems. 5-Substituted dipyrromethanes are important synthetic intermediates and are
well-established precursors for the synthesis of symmetric and asymmetric meso substituted
porphyrins, expanded porphyrins, and other porphyrin analogues [9a]. Not only are they key
precursors to meso-substituted asymmetric porphyrins, but also calix[4]pyrroles and
calix[4]phyrin macro cycles, which are well established as redoxactive or optical sensors for
anions [9b].
2.3 Experimental
2.3.1 Synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin [F20TPP]
by Alder and Longo Technique
Dry chloroform (1.5 litres) was taken in 3 litres three necks round bottom flask fitted with
nitrogen inlet tube, a reflux condenser and a septum. The chloroform was degassed with a
steam of nitrogen for 10 minutes. Freshly distilled pyrrole (1.0 ml, 14.5 mmol) and 2,3,4,5,6-
pentafluorobenzaldehyde (2.85 g, 14.5 mmol) were added to chloroform with stirring. The
reaction mixture was bought to reflux under nitrogen and boron trifluoride etherate (2.5 M
solution in chloroform, 3.88 ml, 4.6 mmol) was injected through septum. The reaction
mixture was refluxed with stirring, under nitrogen atmosphere for 1 hour during which the
colour changed from dark yellow to dark brown. After 1 hour, nitrogen flow was shut off and
DDQ (2.64 mmol) was added to the reaction, and the reaction mixture was refluxed for
additional 1 hour, after which it was cooled to room temperature and triethylamine (0.58 ml,
4.6 mmol) was added with stirring. The solvent was then evaporated to dryness in rotatory
evaporator. The product was chromatographed silica gel column using petroleum ether as
eluent. The evaporation of the eluent of the third fraction of the column gave the required
porphyrin as brown crystals.
2.3.2 Synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[F20TPP] by [2+2] Condensation
2.3.2.1 Synthesis of 5-(pentafluorophenyl)dipyrromethane by Amberlyst-15:
A solution of pentafluorobenzaldehyde (2.0 mL, 16.2 mmol) and pyrrole (50 mL, 720 mmol)
was degassed by bubbling the mixture with argon for 10 min. Cation exchange resin
amberlyst-15 (2 g) was added to this mixture. The solution was stirred at room temperature.
After 12 hr, the reaction mixture was diluted with CH2Cl2 (400 ml), 100 ml of triethylamine
was added to prevent acidolysis of the mesophenyl dipyrromethane and filtered. The filtrate
was washed with water (400 ml) and the organic layer was dried over Na2SO4. The solvent
was removed under reduced pressure and the unreacted pyrrole was removed by vacuum
distillation (5–8 mm/30–358C). The resulting pale yellow amorphous solid was purified by
crystallization or flash chromatography using pet ether–ethylacetate–triethylamine (85:14:1)
to give (pentafluorophenyl) dipyrromethane as white crystals (70–80%).
2.3.2.2 Synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[F20TPP] by using 5-(pentafluorophenyl) dipyrromethane
A mixture of 5-(pentafluorophenyl) dipyrromethane (2 mmol) and pentafluoro benzaldehyde
(2 mmol) in 1:1 ratio for (2+2) condensation of DPM ,was stirred under a nitrogen
atmosphere in dichloromethane [CH2Cl2] (50 ml) in presence of a cation exchange resin i.e.,
amberlyst-15 (1 g) at 258 C for 12 hr. DDQ was then added and the reaction mixture was
further refluxed for 3 h, cooled and filtered. The filtrate was concentrated and the crude
product was subjected to soxhlet purification using methanol. The methanol insoluble product
was then purified by flash chromatography on silica gel to afford pink crystals of porphyrins.
2.4 Characterisation
2.4.1 H1 NMR
1H NMR of Pentafluoro dipyrromethane
1H NMR (400 MHz,CDCl3) δ ppm: 5.87 (1H, s, CH), 6.00 (2H, m, ArH), 6.13– 6.16 (2H, m,
ArH), 6.70 – 6.71(2H, m, ArH), 8.14 (2H, brs, NH).
1H NMR of F20TPP
1H NMR (CDCl3) δ ppm: 8.92 (s, 8H, β-pyrrole H). -2.92 (s, 2H, N-pyrrole H)
2.4.2 UV-Vis Spectroscopy
UV-Vis spectra of F20TPP
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 412.44 (1.01), 506.43 (0.09), 583.48 (0.03).
2.5 Conclusion
Here we have synthesized one meso-substituted symmetrical porphyrin i.e., 5,10,15,20-tetra-
(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin [F20TPP] by two different techniques. First by
Alder and Longo technique and secondly by [2+2] condensation of Dipyrromethane (DPM)
by using acid catalyst resin (Amberlyst-15) and studied the products with H1 NMR and UV-
Vis spectra.
2.6 References
[1] J S Lindsey,“The Porphyrin Handbook”, K M Kadish, K M Smith, R Eds Guilard,
Academic Press,San Diego, 2000,46.
[2] M G H Vicente, K M Smith. Porphyrins and derivatives: Synthetic strategies ad
reactivity profiles. Curr Org Chem.,2000,4,139-174.
[3] (a) P Rothemund. Formation of Porphyrins from Pyrrole and Aldehydes. J Am Chem
Soc.,1935, 57(10),2010-2011. (b) G PArsenault, E Bullock, S F MacDonald. Pyrromethanes
and Porphyrins Therefrom. J Am Chem Soc.,1960,82,4384-4389. (c) L T Nguyen, M O
Senge, K M Smith. Simple Methodology for Syntheses of Porphyrins Possessing
Multiple Peripheral Substituents with an Element of Symmetry.J Org
Chem.,1996,61(3),998-1003.
[4] M O Senge, W W Kalisch, I Bischoff. The Reaction of Porphyrins with
Organolithium Reagents. Chem Eur J., 2000,6(15),2721-2738.
[5] X Feng, I Bischoff, M O Senge. Mechanistic Studies on the Nucleophilic Reaction of
Porphyrins with Organolithium Reagents. J Org Chem.,2001,66(26),8693-8700.
[6] R P Brinas, C Bruckner. Synthesis of 5,10-diphenylporphyrin. Tetrahedron.,
2002,58(22),4375-4381.
[7] B Corain, M Kralik. Dispersing metal nanoclusters inside functional synthetic resins:
scope and catalytic prospects. J Mol Catal A:Chem., 2000,159(2),153-162.
[8] (a) L I Grosseweiner. Photodynamic therapy, Chap 8, in “The Science of Phototherapy”,
CRC Press, London, 1994, 139-155. (b) J S McCaughan Jr. Photodynamic Therapy: A
Review. Drugs & Aging.,1999,15,49-68.
[9] (a) J S Lindsey. In “Metalloporphyrins Catalysed Oxidations”, Kluwer Academic
Publishers, The Netherlands, 1994, 49-86. (b) A Jasat, D Dolphin. Expanded porphyrins
and their heterologs. Chem Rev.,1997,97,2677-2340.
CHAPTER 3
METALLOPORPHYRINS
3.1 Introduction
The prophyrin ring provides a vacant site at its centre, ideally suited for metal incorporation.
The NH protons inside the ring of porphyrins possess acidic character and hence can get
deprotonated to give porphyrinato ions. These dianion species with their electronically
sensitive planar n-framework and central cavity with more or less rigid size exhibit
remarkable ligation characteristic towards metal ions. Thus derivatives of porphyrins with
almost all metals and semimetals have been synthesised [1].
A crucial factor to form stable metalloporphyrins seems to be the compatibility of porphyrin
ring size with the ionic radii of the metal cations [2]. Hence stable complexes generally result
when these two sizes match while their instability tends to increase when the size of the
cation is too big or too small with very few exceptions. The porphyrinato dianion is ideally
suited to act as a tetradenate ligand with metal ions [3]. Thus the minimum coordination
number of the metal ion possible in a metalloporphyrin is four. A size matching divalent
metal ion would give neutral complex, while a higher valent cation would carry with it
balancing anion(s) mostly covalently bound with the metal, in addition to the
porphyrinato ion.
The normal coordination geometry around the metal ion in the former species would be
square planar, while in the latter case the coordination geometry would be square pyramidal.
Coordination number greater than four is also possible. The two ligands of the six coordinate
metalloporphyrins are found on the opposite sides of the porphyrinato plane yielding
complexes with tetragonal or octahedral geometries [3]. Ability to exhibit variable oxidation
states of metals in their metalloporphyrins is another important feature in this class of
compounds. They are also capable of stabilizing metal ions in their unusual oxidation states,
which have resulted in extensive studies revealing interesting chemistry.
3.2 Properties
Metalloporphyrins can be divided into two groups based on their UV-vis and fluorescence
properties [4]. Regular metalloporphyrins contain closed-shell metal ions (d 0 or d 10 )—for
example Zn II , in which the d π (dxz , dyz ) metal-based orbitals are relatively low in energy.
These have very little effect on the porphyrin π to π* energy gap in porphyrin electronic
spectra (Figure 1). Hypsoporphyrins are metalloporphyrins in which the metals are of d m , m
= 6–9, having filled d π orbitals. In hypsoporphyrins there is significant metal d π to
porphyrin π* orbital interaction (metal to ligand π- backbonding) [Figure 2]. This results in
an increased porphyrin π to π* energy separation causing the electronic absorptions to
undergo hypsochromic (blue) shifts.
Figure 1 Molecular Orbital Diagram for metalloporphyrins. Interactions between dπ and π* occur in
hypsoporphyrins.
Figure 2 The dπ metal orbital overlap with the π system of the porphyrin ring.
The lowest energy excited singlet states of porphyrins can be thought of as being formed
from the molecular orbitals you examined above. An excited singlet state with an a1ueg
configuration is formed by promoting an electron from the a1u orbital to an eg orbital.
Likewise, an excited singlet state with an a2ueg configuration is formed by promoting an
electron from the a2u orbital to an eg orbital. These excited singlet states mix to two new
singlet states that are nearly 50:50 mixtures of the unmixed states. The closer in energy the
unmixed states, the greater the degree of mixing.
An electronic transition to the higher energy mixed state, the S2 state, is strongly allowed,
whereas an electronic transition to the lower energy mixed state, the S1 state, is only
weakly allowed. The band in the UV-Vis absorption spectrum due to a transition to the S2
state is the Soret band, and the band due to a transition to the vibration less S1 state is the
α band. The greater the degree of mixing, the less intense the α band relative to the Soret
band.
In the UV-visible spectrum of porphyrin (Figure 3), there is also a vibronic band, the β band,
that appears at slightly lower wavelengths than the α band. The β band is due to transitions to
higher vibrational levels in the S1 state and serves as a "normalization band" in porphyrin
absorption spectra. As a result, the intensity of the α band relative to the β band can serve as a
measure of how close in energy the a2u and a1u orbitals are to each other. For example, if the
a2u and a1u orbitals have essentially the same energy, the degree of mixing will be large, the α
intensity will be small, and, therefore, the α/β intensity ratio will be small. On the other hand,
if the a2u and a1u orbitals are well separated in energy, the degree of mixing will be smaller,
and the α/β intensity ratio will be larger [5].
Figure 3 Typical UV-Visible absorption spectrum of a porphyrin
3.3 Experimental
3.3.1 Synthesis of Iron(III)5,10,15,20-tetraphenyl porphyrin [H2TPPFe(III)Cl]
The metallization of 5,10,15,20-tetraphenylporphyrin (H2TPP) by iron metal is done by
taking 5,10,15,20-tetraphenylporphyrin (H2TPP) (1.2 g, 1.95 mmol) and FeCl2.4H2O (3.0 g,
15.8 mmol) salt and dissolving in DMF (250 ml). This reaction mixture was refluxed for 3 h.
The hot solution was filtered, cooled and diluted hydrochloric acid was added to it in small
portions. The precipitated complex was separated by filtration and was crystallized twice
from a mixture of 1,2-dichloroethane and n-hexane to get iron (III)-5,10,15,20-
tetraphenylporphyrinate chloride.
3.3.2 Synthesis of Zinc 5,10,15,20-tetraphenyl porphyrin [ZnTPP]
The metallation of 5,10,15,20-tetraphenylporphyrin (H2TPP) was done by zinc metal in a
similar fashion as was done for above. The 5,10,15,20-tetraphenylporphyrin (H2TPP) (1.2 g,
1.95 mmol) and zinc acetate [Zn(O Ac)2] (3.0 g, 15.8 mmol) as a metal salt precursor were
taken and dissolved in DMF (250 ml). This reaction mixture was refluxed for 3 h. The hot
solution was filtered, cooled and diluted hydrochloric acid was added to it in small portions.
The precipitated complex was separated by filtration and was crystallized twice from a
mixture of 1,2-dichloroethane and n-hexane. A magenta coloured zinc-5,10,15,20-
tetraphenylporphyrin was thus obtained.
3.3.3 Synthesis of Iron (III) 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[F20TPPFe(III)Cl]
The 5,10,15,20-tetrakis(2’,3’,4’,5’,6’-pentaflourophenyl) porphyrin (H2F20TPP) (49 mg, 0.50
mmol) and FeCL2.H2O (40 mg, 2.0 mmol) were taken in refluxing DMF (40 ml) and
refluxed for 3 hours. The hot solution was filtered and worked up as above. The crude
porphyrin was recrystallized from dichloromethane:hexane solvent mixtures to obtain
iron(III) 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluoro phenyl) porphyrin [F20TPPFe(III)Cl].
3.3.4 Synthesis of zinc 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[ZnF20TPP]
The 5,10,15,20-tetrakiis(2’,3’,4’,5’,6’-pentaflourophenyl) porphyrin (H2F20TPP) (100 mg,
0.25 mmol) and zinc acetate ( 100 mg, 1.0 mmol) were taken in refluxing DMF (20 ml) and
refluxed for 3 hours at 140 C. The hot solution was filtered and worked up as above. The
crude porphyrin was recrystallized from dichloromethane:hexane solvent mixtures to obtain
zinc 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluoro phenyl) porphyrin [ZnF20TPP].
3.4 Characterisation
3.4.1 UV-Vis spectroscopy
UV-Vis spectrum of H2TPPFe(III)Cl
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 377 (0.603), 415.88 (0.94), 510.26 (0.13), 576.55
(0.040).
UV-Vis spectra of ZnH2TPP
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 413.71 (0.82), 544.29 (0.04).
UV-Vis spectrum of F20TPPFe(III)Cl
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 411.74 (0.81), 505.47 (0.15), 561.07 (0.08).
UV-Vis spectrum of ZnF20TPP
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 429.99 (1.99), 555.18 (0.11), 595.5 (0.06).
3.5 Conclusion
Here we have synthesized two different metalloporphyrins. Firstly the simple 5,10,15,20-
tetraphenyl porphyrin [H2TPP] made to metallated with Iron and Zinc salts to form
Iron(III)5,10,15,20-tetraphenyl porphyrin [H2TPPFe(III)Cl] and Zinc 5,10,15,20-tetraphenyl
porphyrin [ZnH2TPP]. Secondly a meso substituted symmetrical porphyrin i.e., 5,10,15,20-
tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin [F20TPP] also metallated with Iron and Zinc
salts to form Iron (III) 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[F20TPPFe(III)Cl] and Zinc 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[ZnF20TPP]. These compounds were studied by UV-Vis Spectroscopy.
3.6 References
[1] J W Buchler, "The Porphyrins" D Dolphin (Ed), Academic, New York, Part A,
Structure and Synthesis 1978,1.
[2] J W Buchler, "Porphyrins and Metalloporphyrins", K M Smith (Ed),Elsevier, 1975.
[3] W R Scheidt. Trends in metalloporphyrin stereochemistry. Acc Chem Res.,
1977,10(9),339-345.
[4] D F Marsh, L M Mink. Microscale Synthesis and Electronic Absorption Spectroscopy
of Tetraphenylporphyrin H2(TPP) and Metalloporphyrins ZnII(TPP) and NiII(TPP). J
Chem Ed.,1996,73,1181.
[5] http://www.molecules.org/experiments/Walters/Walters.html
CHAPTER 4
PORPHYRIN NANOPARTICLES
4.1 Introduction
Many of the unique properties of nanoscaled materials, especially their electronic, photonic
and magnetic properties cannot be achieved using the corresponding atomic, molecular,
polymeric or macroscopic materials. Porphyrins are representative of photofunctional
organics, and they show remarkable photo-, electro- and biochemical properties that
contribute to light harvesting [1]. Hence, meso/nano-scaled porphyrin assemblies or particles
are expected to be promising candidates for use in photonic devices [2]. To fabricate organic
nano-architectures composed of porphyrins, it should be recognized that van der Waals
intermolecular and hydrogen-bonding interactions as well as the electrostatic attraction are
responsible for the specific electronic/optical properties that are fundamentally different from
those of inorganic metals or semiconductors [3]. The formation of nanoscaled colloidal
particles of porphyrins can be accomplished by adding water to a solution of a hydrophobic
porphyrin in water-miscible organic solvents such as THF, DMSO, DMF, or CH3CN with a
few percent of a low molecular weight polyethylene glycol (PEG). This mixed solvent
approach is an efficient means to make large quantities of nanoparticle colloids (20–500 nm
diameter) of a variety of porphyrins [4–5].
4.2 Properties
The properties of many nanoscaled particles are substantially different than those of bulk
materials composed of the same atoms or molecules. Nanometer-scale particles composed of
metals, metal oxides, and other inorganic materials have been reported as have a few
composed of organic molecules [6-11]. Organic molecules also are used in self-assembling
processes to prepare “soft” nanostructures such as spheres and tubes [12,13]. Thus,
nanoscaled particles composed of porphyrins are expected to have chemical activities
significantly different from those of the free porphyrins or of those immobilized onto/into
supports. Porphyrin nanoparticles are promising components of advanced materials because
of the rich photochemistry, stability, and proven catalytic activity [14]. In analogy to
inorganic and other organic nanoparticles, it is expected that nanoparticles of porphyrins will
have unique photonic properties not obtainable by larger-scaled materials containing the
macrocycle, or by the molecules themselves [15] the formation of nanoparticles of catalytic
porphyrins will enhance stability and catalytic rate because of the structure of the aggregate
and the greater surface area.
The UV-vis spectra of porphyrin nanoparticles are significantly different compared to the
spectra of the corresponding porphyrin solutions (Figure 1). Soret bands are found to be
broadened and/or split. The arrangement of macrocycles in aggregates generally fall into two
types, ”J”(edge-to-edge) interactions are characterized by red shifts and “H” (face-to-face)
interactions are characterized by blue shifts. The optical spectra suggest both types of
interactions in the nanoparticles and are well understood to be indicative of electronic
coupling of the chromophores. The extent of J versus H aggregation depends on the specific
porphyrin used.
Volume of water did not have major effect on the positions of the Soret and Q bands of the
porphyrin nanoparticles, but with increasing volume of water as a guest solvent, the
absorbance of the porphyrin nanoparticles decreased. By increasing the volume of the guest
solvent, just the solution of the nanoparticles become more diluted and the intensities of the
absorption become less but the position of the spectra did not change; this shows that the
volume of the guest solvent did not affect the shape of the nanoparticles.
4.3 Application
There are a variety of possible applications of porphyrin nanoparticles that derive from the
photonic properties of both the component molecule and the nanoscaled dimensions of the
particle. Many of these nanoparticles, when the porphyrin contains a redox-active transition
metal (e.g., Fe,Co.Mn) are more efficient catalysts on a per porphyrin basis than the
individual porphyrins adsorbed onto supports. The fluorescence properties of nanoparticles
containing the free base or closed-shell metalloporphyrins or the phosphorescence of these or
other metalloderivatives such as the Pd(II) and Pt(II) can be exploited for sensors and
displays.
The agent used to prevent agglomeration can be covalently attached to the dye forming the
particle or as part of the solvent system. It also demonstrates that these and other types of
dyes with a range of photonic properties do not need to be prepared by encapsulation in
matrices or by designed self-assembly a priori. The matrix may severely limit the
functionality of the particles in the former case, and at present, this size of particle is difficult
to achieve in the latter. A “green” synthesis of porphyrins will also make these materials
more economically feasible.
4.4 Experimental
4.4.1 H2TPP Nanoparticles
The formation of nanoscaled colloidal particles of hydrophobic porphyrins such as
5,10,15,20-tetraphenylporphyrin (H2TPP) and many of the metallo derivatives can be
accomplished by adding water (guest solvent) to a solution of a hydrophobic porphyrin in
THF, DMSO, DMF, or CH3CN (host solvent) with a few percent of a low molecular weight
PEG such as HO(C2H4O)4CH3 [16] or a non-ionic surfactant. Stabilizers such as PEG are
essential for the formation of stable colloidal systems by host–guest solvent methods; reports
on nanoparticle systems of porphyrinoids without this component are misleading or
inaccurate since the porphyrins rapidly and quantitatively precipitate [17]. Other inquiries
into the formation and activity of nanoparticles of dyes such as phthalocyanines have been
reported [18]. The mixed solvent approach is an efficient means to make large quantities of
nanoparticles colloids of a variety of porphyrins. In terms of scale-up, the particle size and
distribution of batches using 20 g of porphyrin correlate well with the small batches of 20
mg.
4.4.1.1 Synthesis of 5,10,15,20-tetraphenyl porhyrin [H2TPP] nanoparticles by Mixing
Solvent technique
By dissolving hydrophilic 5,10,15,20-tetraphenyl porhyrin [H2TPP) ( 2 mg) of porphyrin in
0.5 mL of water, followed by rapid addition of 5 mL of CH3CN. For nanoparticles composed
of hydrophobic/amphipathic porphyrins, 25 µL of (triethyleneglycol)monomethyl ether was
mixed into a 0.2 mL (0.1mM) solution of the porphyrin in DMSO, and then 2.5 mL of water
was added rapidly (Scheme 4.1).
The four ethyleneglycol monomethyl ether derivatives appended to porphyrin Fe(III) adds in
the formation and stabilization of nanoparticles. Consistent with other nanoparticle
preparations, the stabilizer prevents agglomeration and is a factor in determining nanoparticle
size [19].
Scheme 4.1 Synthesis of H2TPP nanoparticles
4.4.2 5,10,15,20-Tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin [F20TPP]
nanoparticles
Colloidal nanoparticles of F20TPP are of interest because of the diverse photonic and catalytic
applications. the particle size and stability depends on the structure of the
porphyrin/metalloporphyrin, the exact preparative procedures, and conditions in which they
are examined (e.g. in solution, concentration, on a surface). The perfluorophenyl groups of
5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl) porphyrin, (F20TPP) are widely recognized
to impart stability to redox catalysts of the metallo derivatives [20-22] and to enhance the
luminescence properties of especially the Pd(II) and Pt(II) species in applications such as
organic LEDs and oxygen sensors [23-25]. F20TPP forms stable nanoparticles under a wide
variety of conditions: stabilizer type and concentration, host solvents, and solvent : water
ratios. One reason for the wide range of processing conditions that yield stable colloids of
F20TPP may be attributed to the unique solvation properties of the perfluoro-phenyl moieties.
Porphyrins bearing only hydro- or fluoro-carbon groups (e.g. F20TPP, TPP) tend to form
nanoparticles with sizes and distributions that are modestly dependent on the exact
chemical structure and concentration of the stabilizer. Conversely, porphyrins with polar
functional groups (e.g. meso pyridyl groups, and hydroxy, carboxy, amino, or sulfonato
groups on the phenyl) exhibit a greater range of particle size with different kinds and amounts
of the stabilizer. This latter observation is likely due to the stronger interactions between the
solute and the solution components (host and guest solvents, and stabilizer). Thus for polar
porphyrins it is possible to tune the sizes and morphology of particles over a greater range by
changing the chemical nature and the quantity of the stabilizer. The complex intermolecular
interactions between amphipathic molecules such as the polyethylene glycols with water, the
polar host solvent, and the porphyrin solute are essential for the formation of stable colloids.
4.4.2.1 Synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin
[F20TPP] nanoparticles by Sonication method
The 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl) porphyrin [F20TPP] nanoparticles
were prepared by means of a sonication technique. Triethylene glycol monomethyl ether (100
μL) as a stabilizer was added to stock solution of F20TPP in THF (1.22 mM for F20TPP, 200
μL) followed by addition of 20 ml water with vigorous mixing and after that was sonicated
for 50 min at 60˚C (Scheme 4.2).
Scheme 4.2 Synthesis of F20TPP nanoparticles
4.5 Characterization
4.5.1 TEM
TEM image of H2TPP nanoparticles
TEM image of F20TPP
TEM images revealed the speherical morphology of the synthesized Organic nanoparticles.
4.5.2 UV-Vis Spectroscopy
UV-Vis spectrum of H2TPP bulk in DMF
UV-Visible [CHCl3, λmax/ nm, (Amax)]: 416.43 (1.75), 513.36 (0.07), 547.82 (0.03), 590.41
(0.01), 645.67 (0.01).
UV-Vis of H2TPP nanoparticles in water
UV-Visible [ λmax/ nm, (Amax)]: 424.97 (0.38), 520.97 (0.10), 554.19 (0.05), 594.32 (0.04),
651.10 (0.03).
UV-Vis spectrum of F20TPP Nanoparticles
UV-Visible [ λmax/ nm, (Amax)]: 424.97 (0.49), 567.97 (0.56), 556.19 (0.36), 629.10 (0.31).
4.6 Conclusion
Here we synthesized two organic nanoparticles by two different techniques. Firstly we did
synthesis of 5,10,15,20-tetraphenyl porhyrin [H2TPP] nanoparticles by solvent mixing
method and secondly synthesis of 5,10,15,20-tetra-(2’,3’,4’,5’,6’-pentafluorophenyl)
porphyrin [F20TPP] nanoparticles by sonication technique. Results were examined through
TEM images and characteristic UV-Vis spectra.
4.7 References
[1] J W Buchler, "The Porphyrins" D Dolphin (Ed), Academic, New York, Part A,
Structure and Synthesis, 1978,1.
[2] D Ostfeld, M Tsutsui. Novel metalloporphyrins. Synthesis and applications. Acc Chem
Res., 1974,7(2),52-58.
[3] O A Golubchikov, B D Berezin. Applied Aspects of the Chemistry of the Porphyrins.
Russ Chem Rev.,1986,55(8),1361-1389.
[4] O Hayashi, "The Enzymes" P Boyer, H Lardy, K. Myrback (Eds), Academic Press, New
York, 1963,8.
[5] A L Lehinger, "Biochemistry", Kalyani Publishers, New Delhi, 1978.
[6] W Xu, H Guo, D L Akins. Aggregation of Tetrakis(p-sulfonatophenyl)porphyrin
within Modified Mesoporous MCM-41. J Phys Chem B., 2001,105(8),1543-1546.
[7] E V Keuren, E Georgieva, J Adrian. Kinetics of the Formation of Organic Molecular
Nanocrystals. J Nano Lett., 2001,1(3),141-144.
[8] H Wiese, D Horn. Fiber-Optic Quasielastic Light Scattering in Concentrated
Dispersions: The On-Line Process Control of Carotenoid Micronization. Ber
Bunsen-Ges Phys Chem., 1993,97(12),1589-1596.
[9] F Debuigne, L Jeunieau, L J Wiame, J B Nagy. Synthesis of Organic Nanoparticles in
Different W/O Microemulsions. Langmuir., 2000,16(20),7605-7611.
[10] H B Fu, J N Yao. Size Effects on the Optical Properties of Organic Nanoparticles. J
Am Chem Soc., 2001,12(7),1434-1439.
[11] H Matsuda, E Van Keuren, A Masaki, K Yase, A Mito,C Takahashi, H Kasai, H
Kamatani, S Okada, H Nakanishi. Nonlinear optical properties of J-aggregated
Merocyanine dye Microcrystals in polymer matrices. Nonlinear Opt., 1995,10,123-128.
[12] M Li, M Jiang, L Zhu, C Wu. Novel Surfactant-Free Stable Colloidal Nanoparticles
Made of Randomly Carboxylated Polystyrene Ionomers.
Macromolecules.,1997,30(7),2201-2203.
[13] Self-assembly reviews:(a) J-M Lehn. Perspectives in Supramolecular Chemistry:
From Molecular Recognition Towards Self- Organization. Pure Appl
Chem.,1994,66,1961-1966.(b) J S Lindsey. ChemInform Abstract: Self-Assembly in
Synthetic Routes to Molecular Devices. Biological Principles and Chemical Perspectives: A
Review. New J Chem.,1991,15,153-180.(c) P J Stang, B Olenyuk. Self-Assembly,
Symmetry, and Molecular Architecture: Coordination as the Motif in the Rational
Design of Supramolecular Metallacyclic Polygons and Polyhedra. Acc Chem
Res.,1997,30(12),502-518.
[14] (a) S Belanger, J T Hupp. Porphyrin-Based Thin-Film Molecular Materials with
Highly Adjustable Nanoscale Porosity and Permeability Characteristics. Angew Chem
Int Ed.,1999,38(15),2222-2224. (b) M J Crossley, J K Prashar. Thiophene-Appended
Porphyrin Systems. Tetrahedron Lett.,1997,38(38),6751-6754.
[15] (a) J H Chou, M E Kosal, H S Nalwa, N A Rakow, K S Suslick. “The Porphyrin
Handbook”, K M Kadish, K M Smith, R Guilard, Eds Academic Press, New York,
2000,6,43.(b) J C Chambron, V Heitz, J P Sauvage. “The Porphyrin Handbook”, K M
Kadish, K M Smith, R Guilard, Eds Academic Press, New York, 2000,6,1.
[16] X Gong, T Milic, C Xu, J D Batteas, C M Drain. Preparation and Characterization of
Porphyrin Nanoparticles. J Am Chem Soc.,2002,124(48),14290–14291.
[17] Y Takahashi, H Kasai, H Nakanishi, T M Suzuki. Test Strips for Heavy-Metal Ions
Fabricated from Nanosized Dye Compounds. Angew Chem., Int Ed.,2006,45(6),913–916.
[18] (a) C Nitschke, S M O’Flaherty, M Kroll, W J Blau. Material Investigations and
Optical Properties of Phthalocyanine Nanoparticles. J Phys Chem B.,2004,108(4),1287-
1295. (b) A de la Escosura, M V Martinez-Diaz, P Thordarson, A E Rowan, R J M Nolte, T
Torres. Donor−Acceptor Phthalocyanine Nanoaggregates. J Am Chem
Soc.,2003,125,12300–12308.
[19] C M Drain, F Nifiatis, A Vasenko, J D Batteas. Porphyrin Tessellation by Design:
Metal-Mediated Self-Assembly of Large Arrays and Tapes. Angew Chem Int Ed., 1998,
37(17), 2344-2347. (b) C M Drain, J M Lehn. Self-assembly of square multiporphyrin
arrays by metal ion coordination. Chem Soc.,Chem Commun., 1994,2313-2315. (c) T N
Milic, N Chi, D G Yablon, G W Flynn, J D Batteas, C M Drain. Controlled Hierarchical
Self-Assembly and Deposition of Nanoscale Photonic Materials. Angew Chem., Int
Ed.,2002, 42(12), 2117-2119.
[20] L Qi, H Colfen, M Antonietti. Synthesis and Characterization of CdS Nanoparticles
Stabilized by Double-Hydrophilic Block Copolymers. Nano Lett.,2001,1(2),61-65.
[21] M W Grinstaff, M G Hill, J A Labinger, H B Gray. Mechanism of catalytic
oxygenation of alkanes by halogenated iron porphyrins. Science.,1994,264,1311–1313.
[22] M Selke, M F Sisemore, J S Valentine.The Diverse Reactivity of Peroxy Ferric
Porphyrin Complexes of Electron-Rich and Electron-Poor Porphyrins. J Am Chem
Soc.,1996,118(8),2008-2012.
[23] T Ikeue, Y Ohgo, T Saitoh, T Yamaguchi, M Nakamura. Factors Affecting the
Electronic Ground State of Low-Spin Iron(III) Porphyrin Complexes. Inorg
Chem.,2001,40(14),3423–3434.
[24] G Khalil, M Gouterman, S Ching, C Costin, L Coyle, S Gouin, E Green, M Sadilek, R
Wan, J Yearyean, B Zelelow. Synthesis and spectroscopic characterization of Ni, Zn, Pd
and Pt tetra(pentafluorophenyl)porpholactone with comparisons to Mg, Zn, Y, Pd and
Pt metal complexes of tetra(pentafluorophenyl)porphine. J Porphyrins
Phthalocyanines.,2002,6(2),135–145.
[25] B Zelelow, G E Khalil, G Phelan, B Carlson, M Gouterman, J B Callis, L R Dalto. Dual
luminophor pressure sensitive paint:II. Lifetime based measurement of pressure and
temperature. Sens Actuators B.,2003, 96(1-2), 304–314.