The second-order nonlinear optical (NLO) properties of two tetrathiafulvalene (TTF)-fused electron donor-acceptor dyads have been determined using the Electric Field Induced Second Harmonic generation (EFISH) technique and theoretically rationalized. Dyads TTF-dppz (1) and TTF-BTD (2) were obtained by direct fusion of a TTF electron donor unit either with a dipyrido[3,2-a:2[prime or minute],3[prime or minute]-c]phenazine (dppz) or a benzothiadiazole (BTD) electron acceptor moiety. Dyad 1 acts as a reversible acido-triggered NLO switch by protonation/deprotonation at two nitrogen atoms of the dppz acceptor moiety induced by sequential exposure to HCl and ammonia vapors. Dyad 2, on the other hand, displays redox-tunable NLO properties upon two consecutive oxidations to its radical cation 2+[radical dot] and dication 22+ species. The resulting final dication 22+ exhibits an inversion of the sign of [small beta]0, due to a completely inverted distribution of the frontier molecular orbitals with respect to those of its neutral species, leading to a scarcely polar species in the excited state, as indicated by the theoretical calculations.

Stimuli-responsive NLO properties of tetrathiafulvalene-fused donor-acceptor chromophores

Forni A;Lucenti E;
2017

Abstract

The second-order nonlinear optical (NLO) properties of two tetrathiafulvalene (TTF)-fused electron donor-acceptor dyads have been determined using the Electric Field Induced Second Harmonic generation (EFISH) technique and theoretically rationalized. Dyads TTF-dppz (1) and TTF-BTD (2) were obtained by direct fusion of a TTF electron donor unit either with a dipyrido[3,2-a:2[prime or minute],3[prime or minute]-c]phenazine (dppz) or a benzothiadiazole (BTD) electron acceptor moiety. Dyad 1 acts as a reversible acido-triggered NLO switch by protonation/deprotonation at two nitrogen atoms of the dppz acceptor moiety induced by sequential exposure to HCl and ammonia vapors. Dyad 2, on the other hand, displays redox-tunable NLO properties upon two consecutive oxidations to its radical cation 2+[radical dot] and dication 22+ species. The resulting final dication 22+ exhibits an inversion of the sign of [small beta]0, due to a completely inverted distribution of the frontier molecular orbitals with respect to those of its neutral species, leading to a scarcely polar species in the excited state, as indicated by the theoretical calculations.
2017
Istituto di Scienze e Tecnologie Molecolari - ISTM - Sede Milano
tetrathiafulvalene
Second Order Non Linear Optics
EFISH
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/341824
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