Molecular Photoinduced electron transfer (PET) Sensors
I. Triphenyl amine-based sensors of dicarboxylic acids
Selective recognition of dicarboxylic acids is achieved through dual two-site hydrogen bonding with concomitant quenching of fluorescence of the triphenylamine moiety. Theoretical binding energy is a good indicator of the selectivity.
(1) open receptor systems : highest selectivity for succinic acid.
(glutaric acid) (adipic acid) (adipic acid)
(2) closed receptor system: highest selectivity for malonic acid
(malonic acid)
(succinic acid) (adipic acid)
References:
1. I. D. Petsalakis, N. Tagmatarchis, G. Rotas and G. Theodorakopoulos, Theoretical study on triphenylamine-based sensors of dicarboxylic acids. J. Molec. Struct. Theochem 807, 11 (2007)
2. K. Ghosh, G. Masanta, R. Frohlich, I. D. Petsalakis and G. Theodorakopoulos, Triphenylamine-based receptors in selective recognition of dicarboxylic acids. J. Phys. Chem. B 113, 7800 (2009)
II. Fluorescent Sensors for Organophosphorus Nerve Agent Mimics: Theoretical study on tertiary amine-fluorophore photoinduced electron transfer (PET) systems, emitting and electron-transfer electronic states
Experimental : T. J. Dale and J. Rebek, Jr. J. Am. Chem. Soc., 128 (2006) 4500
(i) (f)
Suppression of emission in the initial sensor system (i) due to PET. Reaction with organophosphorus nerve-agent mimics leads to cyclization (f) and strong fluorescence.
The theoretical study shows the change of character of the absorbing excited state and the suppression of emission at the equilibrium geometry of the excited state of the initial system (i) as well as the absence of emission suppression in the final form (f).
Table 1: Variation of the transition energy, oscillator strength and character of the lowest excited state of the pyrene-t-amine sensor (i) with geometry optimization following the absorption step.
References
1. I. D. Petsalakis, N. N. Lathiotakis and G. Theodorakopoulos, Theoretical study on tertiary amine-fluorophore photoinduced electron transfer (PET) systems. J. Molec. Struct.: THEOCHEM 867, 64 (2008)
2. I.D. Petsalakis, I.S.K. Kerkines, N.N. Lathiotakis and G. Theodorakopoulos ''Emitting and electron-transfer electronic states of tertiary amine-fluorophore sensor systems'' , Chem. Phys. Lett. 474, 278 (2009).
