RESUMO
Azobenzene derivatives have long been studied for their photochromic behaviour. One of the greatest challenges in this field is the quantitative (E) to (Z) photoconversion triggered by visible light irradiation. In this work, the synthesis and characterization of CuInS2 quantum dots (CIS-QDs) appended with azobenzene units are reported: quantitative (E) â (Z) isomerisation is obtained by visible light (e.g., λex = 533 nm). Interestingly, catalytic amounts of CIS-QDs allow the full photoconversion of ungrafted (E)-azobenzene derivatives into the corresponding (Z)-isomers using visible light. This peculiar behaviour is associated with the direct complexation of the (Z)-isomer on the QD surface.
RESUMO
Donor-acceptor dyads based on BODIPYs have been recently employed to enhance the formation of triplet excited states with the process of spin-orbit charge transfer intersystem crossing (SOCT-ISC) which does not require introduction of transition metals or other heavy atoms into the molecule. In this work we compare two donor-acceptor dyads based on meso-naphthalenyl BODIPY by combining experimental and computational investigations. The photophysical and electrochemical characterization reveals a significant effect of alkylation of the BODIPY core, disfavoring the SOCT-ISC mechanism for the ethylated BODIPY dyad. This is complemented with a computational investigation carried out to rationalize the influence of ethyl substituents and solvent effects on the electronic structure and efficiency of triplet state population via charge recombination (CR) from the photoinduced electron transfer (PeT) generated charge-transfer (CT) state. Time dependent-density functional theory (TD-DFT) calculations including solvent effects and spin-orbit coupling (SOC) calculations uncover the combined role played by solvent and alkyl substitution on the lateral positions of BODIPY.
