Post on 19-Oct-2020
Presenting a novel feature that we have named
Kinetic Fluorescence Switching (KFS), neither
related to ACQ nor AIE. It has been observed with
CdSe QDs capped with meta-carboranyl-
phosphinates (CarbPH(O)OH) in synergy with
tricaprylylmethylammonium chloride (Me1Surf).
KFS is an unreported phenomenon in which a QD
suspension which is highly emissive, quenches in
30-40 minutes but upon shaking (applying kinetic
energy) recovers its emissive properties. This
property is stable up to half a year.
Synergy between Ligands and Cationic Surfactant The attempted synthetic strategies to get the
CdSe@CarbPH(O)O/Me1Surf QDs indicated that a
synergy between CarbPH(O)OH and the
alkylammonium surfactant was required: CarbPH(O)OH
is necessary to produce fluorescence and Me1Surf to
stabilize it. For KFS a combination of both is required.
Somehow it can be compared to the phenomena visible
in lasers produced by the Faraday pointer where the
laser emitted is dependent on the kinetic energy
required in shaking the pointer.
Mechanism: Carboranyl entity produces a full coverage of the surface but
due to the spherical nature of the carborane, it leaves voids
through which alkyl ammonium charge compensating
cations can diffuse. The alkyl ammonium having one methyl
group can easily penetrate through the voids created by the
carborane capping while the ones with more Me groups or
none couldn't interact with the CdSe..
ICMAB acknowledges the Severo Ochoa
Program (MINECO, SEV- 2015-0496)
Kinetic Fluorescence Switching in
Quantum Dots
0 20 40 60 80 100 120 140 160 180 200 220 240 260
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Time in Minutes
After 5 Months
Fresh Sample
Metallacarboranes for molecular electronic
Materials Francesc Teixidor, Clara Viñas, Rosario Núñez, Isabel Fuentes and Arpita Saha.
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) Bellaterra, Spain
Metallacarboranes as redox
indicators for screening of
gene mutation. Anionic metallabisdicarbollides are sandwich
complexes of two [C2B9H11]2- clusters with a
metal ion in the center. In Figure 1 we show
the two metallacarboranes that have been
used in this study. They are soluble in water
and have good reversible electroactive cou-
ples Fe3+/Fe2+ that are suitable to be used in
biosensors (-0.28 and 0.35 V vs Ag/AgCl).
Biosensor development Synthetic or real DNA sequences (S) were immobilized
on a gold screen-printed electrode . The hybridization
process was realised with a complementary sequence
(CS), non complementary sequence (NCS) or mutated
sequence (total, absent or partial hybridization). Figure 2
shows different degree of the metallacarborane
accumulation (Na[FESANE] Figure 1a; Na[Cl6-FESANE]
Figure 1b) due to not identical interaction between
sequences.
By electrochemical measurements, this biosensor
permits better discrimination between the mutated and
wild type samples.
Gene mutation detection: Figure 3 shows peak bar diagrams of the electrochemical
signal obtained using Na[FESANE] as redox indicator in
synthetic and real DNA samples. Na[FESANE] presents a
different interaction between the three sequence cases
giving place to different electrochemical signals.
It can be said that both Na[FESANE] or Na[Cl6-FESANE]
can be used as DNA biosensors for direct detection of
gene mutations associated with genetic diseases.
Figure 2. Scheme of the biosensor development.
Figure 3. Peak current bar diagrams of the biosensor response before and
after the hybridization using Na[FESANE] as redox indicator: (a) synthetic
sequences; (b,c) real DNA sample by PCR. SNP = Single Nucleotide Poly-
morfphsm; DEL= deletion of 3 base pairs.
References
1 T. Garcia-Mendiola, V. Bayon-Pizarro, A. Zaulet, I. Fuentes,
F. Pariente, F. Teixidor, C. viñas and E. Lorenzo, Chem Sci,
2016 , 7, 5786-5797.
Figure 2. Growth curves of PPy doped with different iodo-derivatives of
[Co(C2B9H11)2]- ([1]-). The red arrow correspond to the E1/2 value for every
doping agent.
Redox potential modulation
on Polypyrrole (PPy) films. Metallacarboranes can be used as doping
agents in the electropolymerization of pyrrole
to form PPy. Figure 1 shows different iodode-
rivatives of [Co(C2B9H11)2]- with their respec-
tive redox potential that has been tuned by
dehydroiodination. Each Ppy compound pro-
duces a different material with different value
of the cathodic and anodic peaks, but the
center is the same in all of them (Figure 2).
Figure 1. Chemical structure of the anionic metallacarboranes
[3,3’-Fe(1,2-closo-C2B9H11)2]- (a) and [3,3’-Fe(8,9,12-Cl3-1,2-
closo-C2B9H8)2]- (b).
AuSPE AuSPE-SH-PROBE
ELECTROCHEMICALSIGNAL
METALLACARBORANEACCUMULATION
PROBE IMMOBILIZATION
WT
MUT
HYBRIDIZATION
PARCIAL HYBRIDIZATION
0.0
0.3
0.6
0.9
MUT WT
I / A
Fe
Fe
Figure 1. Different iodo-derivatives of [Co(C2B9H11)2]- with
their respective redox potential.
Figure 1. Graphical Representation of Kinetic Fluorescence Switching
in CdSe Quantum dots capped with Carboranyl Phosphinate.
Figure 2. Pictographic Representation of Kinetic Fluorescence Switching in
CdSe Quantum dots capped with Carboranyl Phosphinate.
Figure 3. (a) Comparison between the different Alkyl Ammoniums.
(b)The PL Switch ON and OFF states are related to the alkyl ammonium and
the voids created due to the spherical shape. of Carborane.
References
1 E. Oleshkevich, F. Teixidor, D. Choquesillo-Lazarte, R. Sillanpää, C.
Viñas, Chem. Eur. J., 2016, 11, 3665–3670.
2 A. Saha, E. Oleshkevich, C. Viñas, F. Teixidor, Submitted.
(a) (b)
Initial Intensity
Decrease in Intensity
with settling of particles
Almost no Intensity
Intensity when shaking
Intensity after shaking
Initial Intensity Intensity
after
particles
settling
ACKNOWLEDGEMENTS This work was supported by MINECO (CTQ2013-44670-R, ) Generalitat de Catalunya (2014/SGR/149), European Network on Smart Inorganic
Polymers (SIPs) (CM1302) and SEA-on-a-CHIP FP7-OCEAN-2013 (614168).
a
b c
a b
Redox active metallacarborane-
decorated octasilsesquioxanes. Polyanionic and electroactive hybrids based on
octasilsesquioxanes bearing metallacarborane units have
been developed by our group. They show remarkable
solubility in organic solvents and outstanding thermal
stability. The metallacarboranes act as independent units
undergoing simultaneously the reversible redox process.
-1.1 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
10 mV/s
Inte
nsity /
mA
Potential / V vs Fc
300 mV/s
25 mV/s 50 mV/s 100 mV/s 200 mV/s
400 mV/s 500 mV/s
Figure 1 shows the structure of metallacarborane-decorated octasilsesquioxanes
and CVs of the Fesane derivative in CH3CN at 1.25·10-4 M and different scan rates.
References 1 J. Cabrera-González, V. Sánchez-Arderiu, C. Viñas, T. Parella, F. Teixidor,
R. Núñez, Inorg. Chem. 2016, DOI: 10.1021/acs.inorgchem.6b02394.
2 Doctoral thesis Justo Cabrera González, http://www.tdx.cat/handle/10803/386417
References 1 P. González-Cardoso, A.-I. Stoica, P. Farràs, A. Pepiol, C. Viñas, F
Teixidor, Chem. Eur. J. 2010, 16, 6660-6665.
2 A. Pepiol, F. Teixidor, R. Sillanpää, M. Lupu and C. Viñas, Angew Chem.
Int. Ed, 2011, 50, 12491-12495.
3 M. Lupu, A. Zaulet, F. Teixidor, E. Ruiz and C. Viñas, Chem. Eur. J., 2015,
21,6888-6897.