Self-Assembly of Molecular Prisms via Pt 3 Organometallic Acceptors and a Pt 2 Organometallic Clip...

Self-Assembly of Molecular Prisms via Pt3 Organometallic Acceptors

and a Pt2 Organometallic ClipSushobhan Ghosh, Bappaditya Gole, Arun Kumar Bar, and Partha Sarathi Mukherjee*

Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560 012, India

Advanced Instrumental Analysis lab

Ji Eun Park

09.08.13

Ref) Organometallics, Vol. 28, No. 15, 2009

Introduction

Ref) (a) Ghosh, S.; Mukherjee, P. S. Organometallics 2008, 27, 316. Schultheiss, N.; Ellsworths, J. M.; Bosch, E.; Barnes, C. L. Eur. J.Inorg. Chem. 2005, 45.

solution fluorescence quenched efficiently by adding nitroaromatics chemical signatures

4,4’,4’’-tris[ethynyl-trans-Pt-(PEt3)2(NO3)]triphenylamine +1,3-bis(3pyridylethynyl)benzene trigonal prism

4,4’,4’’-tris(4-pyridylethynyl)triphenylamine + organometallic Pt2-clip 3c

Introduction

new tripodal Pt3-organometallic acceptor 4,4’,4’’-tris[ethynyl-trans-Pt(PEt3)2(NO3)]triphenylethane + [1,8-bis(4-pyridylethynyl)anthracene] [2 + 3] self-assembled prismatic derivative

Results Synthesis of the Linkers

Ref) (a) Ghosh, S.; Mukherjee, P. S. Organometallics 2008, 27, 316. Kryschenko, Y. K.; Seidel, R. S.; Muddiman, D. C.; Nepomuceno,A. I.; Stang, P. J. J. Am. Chem. Soc. 2003, 125, 9647

Results31P{1H}NMR 195Pt

Synthesis of the Linkers

Results

· Cell dimensions of 1c crystal system, cubic; space group, Pa ; α = 25.4754(5) Å; R=90°

· The optimization of the tripodal linker density functional theory (DFT) calculations Gaussian 03 program, B3LYP functional

· 6-31G for lighter elements (C, H, N, and O) & LanL2DZ for heavier elements (Pt and P).

· X-ray structure analysis I-C(central)-I angle ;110.97°

· Pt environment angles 86.44° and 93.11°,

Synthesis of the Linkers

Ref) Kryschenko, Y. K.; Seidel, R. S.; Muddiman, D. C.; Nepomuceno,A. I.; Stang, P. J. J. Am. Chem. Soc. 2003, 125, 9647

Results

trigonal prism design ; two tritopic donors, six 90°corners, three linear linkers [2+6+3] self-assembly reaction The major disadvantage of three-component self-assembly formation of a mixture

Self-Assembly of Molecular Prisms 3a-d

Results

3b ; yellow precipitate

31P NMR - solvent;CDCl3 - singlet at 15.6 ppm- 1JP-Pt (230 Hz) for the Pt satellites.


Results 31P{1H} NMA ;singlet , 14ppm5 ppm upfield shifted from the 31P{1H}NMR ; 1b


Results

Upfield shift ; phosphorus signal of 1c downfield shift ; Hα, Hβ, H9 protons of the donor ligand


Results

Ref) (a) Ghosh, S.; Mukherjee, P. S. Organometallics 2008, 27, 316.

3a: [M3a- 3NO3]3+ m/z=1452.00 (calcd 1451.66)

[M3a- 4NO3]4+ m/z=1073.49 (calcd 1073.18)

[M3a-5NO3]5+ m/z=846.55 (calcd 845.67)


Results

[M3b-3NO3-]3+

isotropic distribution pattern of the peak , matched well with the theoretically expected pattern


Results Self-Assembly of Molecular Prisms 3a-d

Results

[M3d-3NO3]3+ m/z=1523.50 (calcd 1523.33)

[M3d -5NO3]5+ m/z =890.1 (calcd 889.3)


Results

Obtain single crystals for X-ray diffraction fail

Supramolecule 3d energy minimization is presented


Results

3d spectrum ; 421 and 398 nm corresponding to the anthracene part 309nm ; attributed to platinum-to-ligand (2d) charge transfer

3c spectrum ; 3×10-6M solution430 and 383 nm originating from the anthracene moiety of 1b

3b spectrum ; 1.5×10-5 M solution, 283 nm π-π* transition365 nm metal-to-ligand (2b) charge transfe

3b-d excited at 400 nm ; luminescent behavior & emit beteen400nm and 500 nm

Absorption and Fluorescence Studies.

Results

3b-d Fluorescence spectra in DMF solutions

corresponding photophysical data Table S1

Absorption and Fluorescence Studies.

Conclusion

·Pt3 organometallic acceptor (1c) & nanoscopic conjugated prisms (3a-d) Pt-ethynyl functionality

· tritopic planar donor (2c) and Pt2-organometallic clip (1b) establish the versatility of directional bonding to obtain

· Pt-ethynyl incorporation; assemblies fluorescent.

· conjugated ethynyl functionality assemblies π-electron rich and possible hosts

· 3a, 3c, and 3d chemical signature of many commercial explosives

· Conjugated organic polyethynyl compounds potential sensors for chemical explosives.

Introduction of Heterofunctional Groups onto Molecular Hexagons

via Coordination-Driven Self-Assembly

Young Min Lee

Organic Synthesis Lab.

Department of Chemistry

Koushik Ghosh,† Jiming Hu,†,‡ Hai-Bo Yang,§ Brian H. Northrop,† Henry S. White,*,† and Peter J. Stang*,†

<ref.> J. Org. Chem. 2009, 74, 4828–4833

Abstract

The design and synthesis of two new heterofunctional hexagons containing both redox-active

ferrocenyl and host-guest crown ether functionalities has been achieved via coordination-driven

self-assembly. The size and relative distribution of functional groups on the supramolecular

metallacycles can be precisely controlled. The host-guest recognition properties of the crown

ether moieties and their ability to complex cationic guests to form tris[2]pseudorotaxane complexes

have been investigated. The functional moieties are shown to operate orthogonally, resulting in

discrete supramolecular hexagons that are capable of carrying out a variety of functions both

simultaneously and independently.

Introduction

The design and creation of regularly shaped nanoscale objects, which can serve as the building blocks of supramolecular materials,

is an extremely important goal in material science. They have recently introduced a variety of functionalized 120° platinum acceptors and 120° organic donors and have quantitatively assembled them to form molecular hexagons with six functional groups on their periphery. They envisioned that acceptor-donor-based coordination-driven self-assembly is additionally useful because of the ability to modify functional groups at both the donor and acceptor units. Here they employ 120° acceptor units decorated with one functional

group to self-assemble with 120° donor units decorated with another

functional group to form supramolecular hexagons with six heterofunctional groups.

Result Heterofunctional Hexagons 5 and 6

With the 120° crown ether and ferrocene functionalized precursors in hand, in both donor and acceptor analogues, the self-assembly of heterofunctional hexagons was

investigated.

Upon mixing 120° ferrocenyl donor unit 1 with 120° crown ether functionalized unit 2 in CH2Cl2, heterofunctional hexagon

5 was obtained .

Stirring 120° ferrocenyl acceptor unit 3 with an equimolar amount of

120° crown ether donor unit 4 in CH2Cl2 results in heterofunctional hexagon 6.

Scheme 1. Self-Assembly of Heterofunctional Hexagons

Result Tris[2]Pseudorotaxanes 8 and 9

These heterofunctionalized crown ether derivatives in hand, an investigation of the self-assembly

of tris[2]pseudorotaxanes was carried out to investigate any effect(s) of ferrocene substituents in the binding of crown ether

units.

Within 15 min of adding 3 equiv of dibenzylammonium triflate

salt 7 to a solution of hexagonal metallacycles 5 and 6, tris[2]pseudorotaxanes 8 and 9, respectively, were obtained.

Scheme 2. Entry to Hexagonal Cavity-Cored Tris[2]pseudorotaxanes

Result 1H and 31P NMR spectra of 5

• Figure 1. 1H(a) and 31P(b) NMR spectra of 5 in CD2Cl2

(a)

(b)

Pt PtN

Et3P

PEt3 Et3P

PEt3

N

Pt

Pt

NEt3P

PEt3

PEt3Et3P

N

Pt

Pt

N

PEt3Et3P

Et3P

PEt3

N

O

O

O O

O

O

OO

O

O

OO

O

O

OO

O

O

OO

O

O

O

OO

O

O

O

OO

FeO

O

Fe

OO

Fe

O

O

195Pt satellites

< Hexagon 5 >



(a)

(b)

Pt

Pt

N PEt3

Et3P

Et3P PEt3

N

Pt

Pt

NEt3P PEt3

PEt3

Et3P

NPtPtN

PEt3

Et3PPEt3

Et3P

N

O

O

O O

O

O

OO

O

O

OO

O

O

OO

O

O

OO

O

O

O

OO

O

O

O

OO

FeO

O

Fe

OO

Fe

O

O

195Pt satellites

< Hexagon 6 >


(a)

(b)


Pt PtN

Et3P

PEt3 Et3P

PEt3

N

Pt

Pt

NEt3P

PEt3

PEt3Et3P

N

Pt

Pt

NPEt3Et3P

Et3P

PEt3

N

O

O

O O

O

O

OO

O

O

OO

O

O

OO

O

O

OO

O

O

O

OO

O

O

O

OO

FeO

O

Fe

OO

Fe

O

O

NH2

NH2

NH2195Pt satellites

< Tris[2]Pseudorotaxanes 8 >



(a)

(b)

NH2

Pt

Pt

N PEt3

Et3P

Et3P PEt3

N

Pt

Pt

NEt3P PEt3

PEt3

Et3P

NPtPtN

PEt3

Et3PPEt3

Et3P

N

O

O

O O

O

O

OO

O

O

OO

O

O

OO

O

O

OO

O

O

O

OO

O

O

O

OO

FeO

O

Fe

OO

Fe

O

O

NH2

NH 2

195Pt satellites

< Tris[2]Pseudorotaxanes 9 >

Result Partial 1H NMR spectra

In the corresponding 1H NMR spectra, the-protons showed a relatively dramatic upfield shift (0.41 ppm) as well as a slight upfield shift of the R-protons (0.04 ppm) due to electron density transfer from the pyridyl donor to the metal acceptor.

A 0.45 ppm downfield shift of the signal for the benzylic methylene protons adjacent to the NH2

+ center was observed, and protons Hα, Hβ, and Hγ of of the crown ether moiety exhibited upfield shifts.

• Figure 8. Partial 1H NMR spectra of crown ether acceptor 2 (A), ferrocenyl donor 1 (B), mixed hexagon 5 (C), and pseudorotaxane 8 (D).

Result ESI-MS spectra of hexagon 5 and 6

In the ESI mass spectra of heterofunctionalized hexagon 5, a

peak attributable to the loss of four triflate counterions, [M - 4OTf]4+ where M represents the intact assembly, was observed at

m/z = 1563.9.

The ESI/MS spectra of 6 exhibited characteristics very similar to those of 5. The ESI/MS spectra showed one charged state at

m/z = 1553.4 corresponding to the [M - 4OTf]4+ species, and its

isotopic resolution is in excellent agreement with the theoretical

distribution.

• Figure 5. Calculated (top) and experimental (bottom) ESI-MS spectra of hexagon 5 (A) and 6 (B).

Result ESI-MS spectra of 8 and 9

• Figure 6. Calculated (top) and experimental (bottom) ESI-MS spectra of 8.

• Figure 7. Calculated (top) and experimental (bottom) ESI-MS spectra of 9.

The self-assembly of hexagonal cavity-cored tris[2]pseudorotaxanes 8 and 9 was also confirmed by ESI-MS spectrometry.

Two peaks at m/z = 1429.4 and 1824.8 were observed, corresponding to [M - 5OTf]5+

and [M - 4OTf]4+, respectively, for 8, as were peaks attributable to [M - 5OTf]5+ and [M - 4OTf]4+ of 9 at m/z = 1421.1 and 1813.4, respectively.

The host:guest stoichiometry for

heterofunctional supramolecular

assemblies 8 and 9 was established

using the nonlinear leastsquares

fit method based 1H NMR titration

experiments.

Fitting the data to a 1:3 binding

mode for the hosts gave host-guest

association constants.

Result Pseudorotaxane Stoichiometry and Binding Constant

• Figure 9. 1H NMR titration isotherms of 8 (A) and 9 (B), recorded at 500 MHz in CD2Cl2 at 298 K, indicating the change in chemical shift of the proton signal corresponding to the γ-H of the crown ether.

Ks.1 (M−1) Ks.2 (M−1) Ks.3 (M−1)

8 (2.45±0.44)×103 (1.66±0.19)×103 (4.02±0.19)×102

9 (2.09±0.33)×104 (1.83±0.06)×103 (7.83±0.40)×101

a CD2Cl2, 298 K.

Table 1. Thermodynamic Binding Constants of Poly[2]pseudorotaxanes 8 and 9a

Result Simulated molecular models of 5 and 8

• Figure 10. Simulated molecular models of 5 and 8, optimized with the molecular mechanics force field. Color scheme: C = gray, O = red, N = blue, P = purple, Pt = yellow, and R2NH2

+ hydrogen atoms =green, Fe = purple all other hydrogen atoms have been removed for clarity.

Result Simulated molecular models of 6 and 9

• Figure 11. Simulated molecular models of 6 and 9, optimized with the molecular mechanics force field. Color scheme: C = gray, O = red, N = blue, P = purple, Pt = yellow, Fe = pink and R2NH2

+ hydrogen atoms, green (all other hydrogen atoms have been removed for clarity).

Conclusion

They have provided two complementary approaches to generate two new heterofunctional hexagons via coordination-driven self- assembly from a ferrocenyl 120° di-Pt(II) acceptor/donor and a complementary 120° crown ether decorated donor/acceptor unit while exhibiting precise control of size and the distribution of the ferrocene and crown ether moieties.

These heterofunctional hexagons are unique in not only their discrete structures but also the presence of chemically different units, since each unit introduces into the supramolecular structure its own “pieces of information” (in the form of specific properties such as recognition properties, redox levels, etc.) that are preserved faithfully in the structure.

A Catalytically Active, Permanently Microporous MOF with Metalloporphyrin

StrutsAbraham M. Shultz, Omar K. Farha, Joseph T. Hupp,* and SonBinh T. Nguyen*

Received January 10, 2009

Undergraduate forthBAE CHANG GEUN

Figure 1. Synthesis of ZnPO-MOF. The stick representation of the unit

cell is shown on the right-hand side (yellow polyhedra ) Zn, red ) O,green ) F, blue ) N, gray ) C). Solvent molecules, hydrogens, and

disordered atoms have been omitted for clarity.

Figure 2. Space-filling models of the crystal structure of ZnPO-MOF(solvent omitted) showing channels down the a and b crystallographic axes

(yellow ) Zn, red ) O, green ) F, blue ) N, gray ) C, black ) H): (a)15 Å × 9 Å channels along the a axis; (b) 11 Å × 9 Å channels along the

b axis. The channels along the c axis (not shown) are 8 Å × 9 Å.

Figure 3. Plot of product concentrations vs time, showing the initial production

of the various isomers of acetoxymethylpyridine (AMP) from N-acetylimidazole

and pyridylcarbinols. The inset shows data at longer times.

To summarize, they have demonstrated that by appropriate design of organic building blocks (dipyridyl pillars, robust tetratopic carboxylates), metalloporphyrins can be successfully incorporated into a MOF possessing the features needed for effective catalysis, i.e., large pores, permanent microporosity, and fully reactant-accessible active sites. Proof-of-concept catalysis of an acyl-transfer reaction revealed ∼2400- fold rate enhancement, dominated by contributions from LA activation and reactant preconcentration. They hope to report shortly on variants of ZnPO-MOF featuring other metals as active sites and functioning catalytically by other mechanisms.

Conclusion

Coordination-Driven Self-Assembly of Metallodendrimers

Possessing Well-Defined and Controllable Cavities as Cores

Peter J. Stang* et al.Department of Chemistry, University of Utah, 315 South 1400 East,

Room 2020, Salt Lake City, Utah 84112

J. AM. CHEM. SOC. 9 VOL. 129, NO. 7, 2007

Kim You-JungUndergraduate Junior

Introduction

• Supramolecular dendrimers are a recent and important subset of such self-assembled structures.

• As a consequence, attention has recently turned to the self-assembly of dendrimers to provide well-defined nanoscale architectures via a variety of noncovalent interactions such as electrostatic interactions, hydrogen bonding and metal-ligand coordination.

• In particular, cavity-cored dendrimers have recently received considerable attention because of their elaborate structures and potential applications in delivery and recognition.

Introduction

• Previously, Percec et al. reported a library of amphiphilic dendritic dipeptides that self-assemble into helical pores both in solution and in bulk.

• In addition, the possibility to fine-tune the size and shape of the cavities in metallodendrimers would help provide an enhanced understanding of the geometrical requirements necessary for molecular self-assembly.

• Furthermore, this strategy would likely give rise to the design and synthesis of novel supramolecular species with desired functionality arising from their unique interior cavities and dendritic exteriors.

Introduction

• Recently they reported the self-assembly of the first metallodendrimers exhibiting a nonplanar hexagonal cavity with an internal core radius of approximately 1.6nm, by the combination of 120° dendritic donor subunits (substituted with Fréchet-type dendrons) and 120° di-Pt(Ⅱ) acceptor angular linkers in a 1:1 stoichiometric ratio.

• Here they report the results obtained

when they extended the investigations

to the self-assembly of rhomboidal

and “snowflake-shaped” metalloden-

drimers possessing cavities of various

size and shape at the core through

the use of coordination-driven

self-assembly (Figure 1).

Result and Discussion

Synthesis of 120° Angular Dendritic Donor Subunits

The synthesis of [G0]-[G3] 120° donor building blocks

5a-d commenced with acylation of the commercially

available compound 3,5-dibromo-phenol (1) to give 2

(Scheme 1). The 3,5-bis-pyridylethynyl-phenyl ester 3

was prepared by palladium-mediated coupling reaction

from Ester 2 with 4-ethynylpyridine in reasonable yield

(66%). Upon ester hydrolysis and etherification, the [G0]-

[G3] 120° precursors 5a-d (Figure 2), substituted with

Fréchet-type dendrons, were obtained in good yields.


Synthesis of [G0]-[G3]-Rhomboidal Metallodendrimers 7a-d. The combination of 60° units with 120°

linking components will yield a molecular rhomboid. Stirring the [G0]-[G3] 120° angular donors 5a-d with an equimolar amount of the

known60° angular acceptor, 2,9-(trans

Pt(PEt3)2NO3)2-

phenanthrene (6), in CD2Cl2 for 14h resulted in

[2+2] rhomboidal metallodendrimers 7a-d, respectively, in excellent yields (Scheme 2).

The 31P{1H} NMR spectra of the [G0]-[G3]assemblies 7a-d displayed a sharp singlet (ca. 14.6 ppm) shifted up field from the signal of the starting platinum acceptor 6 by approximately 6.4 ppm. This change, as well as the decrease in coupling of the flanking 195Pt satellites (ca. ¢J ) –177Hz), is

consistent with back-donation from the platinum atoms.

In the 1H NMR spectrum of each assembly, the R-

hydrogen nuclei of the pyridine rings exhibited 0.75-

0.78 ppm downfield shifts, and the â-hydrogen

nuclei showed about 0.2 ppm downfield shifts, due

to the loss of electron density that occurs upon

coordination of the pyridine N atom with the Pt(II)

metal center. It is noteworthy that two doublets

were observed for these R-hydrogen nuclei, as this

might be attributed to hindered rotation about the

Pt-N(pyridyl) bond, which has been previously

reported.


In the ESI mass spectra of the [G0]-[G2] assemblies 7a-c, peaks attributable to the loss of nitrate counter ions, [M - 2NO3]2+ (m/z ) 1486.9 for 7a, m/z ) 1699.0 for 7b,

and m/z ) 2123.8 for 7c) and [M - 3NO3]3+ (m/z ) 970.5 for 7a, m/z ) 1112.0 for 7b,

and m/z ) 1394.8 for 7c), where M represents the intact assemblies, were observed (Figure 3)


The ESI-FTICR mass spectrum of the [G3] assembly 7d showed two charged states

at m/z ) 1961.4 and 1455.5, corresponding to the [M-3NO3]3+ and [M – 4NO3]4+ species,

respectively, and their isotopic resolution is

in excellent agreement with the theoretical distribution (Figure 4). The analysis of thesignals observed in the full mass spectraconfirmed that there was no other

assembled species formed.


X-ray crystallographic analysis unambiguously established

the structures of 7a and 7b to be both discrete [G0]- and

[G1]-rhomboidal metallodendritic assembles (Figures 5 and 6). Crystals suitable for single-crystal X-ray analysis were grown by vapor diffusion of n-pentane into a CH2Cl2/CH3COCH3 (v/v 1/1) solution of 7a and 7b

respectively at ambient temperatures for 3 days. Both 7a

and 7b crystallize in the triclinic space group P1 but are not isomorphous to each other, as revealed by theirdifferent unit cell geometries and dimensions.


At the molecular level, both structures feature a well-defined rhombus with an approximately2.3 X 1.3 nm cavity that embodies the porosity of the crystal. In both structures, this cavity is partially filledwith disordered nitrate anions and solvent molecules. The rhomboidal structure of 7a has external dimensions of ca. 3.3 nm long and 2.8 nm wide, while 7b spreads out over an area ofca. 4.2 X 2.8 nm2. Except for a slight difference in their conformation, the two molecules 7a and 7b can almost be superimposed with each other in their rhomboidal parts (Figure 7).


• They have demonstrated that highly convergent synthetic protocols based on the simultaneous assembly of appropriate predetermined building blocks allow the rapid construction of novel cavity-cored metallodendrimers.

• In particular, this approach makes it possible to prepare a variety of metallodendrimers with well-defined and controlled cavities as cores through the proper choice of subunits with predefined angles and symmetry, which enriches the library of different-shaped cavity-cored metallodendrimers.

• Furthermore, the shape of the cavities of the supramolecular dendrimers can be rationally designed to be either a rhomboid or a hexagon.

Conclusion

Self-Assembly of Molecular Prisms via Pt 3 Organometallic Acceptors and a Pt 2 Organometallic Clip...

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