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

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

No

rma

lize

d In

ten

sity o

f E

mis

sio

n

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.