The solvent effect on a styryl-bodipy derivative functioning as an AND molecular logic gate

摘要

We study via DFT and TDDFT calculations the photophysical processes of a styryl-bodipy derivative, (1), of its monometallic complexes 1-M 2+ (M = Ca, Zn, and Hg), and its trimetallic complex (2) unprotonated, protonated and complexed with water molecules in water solvent and in acidic conditions. The main targets of this study are to gain information regarding published reports on fluorophore species mentioning that fluorescent switching results from trace water, to study how 1 behaves in water solvent which is a common used solvent for molecular logic gates (MLG), and how it behaves in acidic conditions. We conclude that in water solvent, as in acetonitrile solvent (which was found before both theoretically and experimentally) there will be a quenching of emission spectra in 1 and 1-M 2+ and a retaining of emission in 2. However, contrary to acetonitrile solvent, in water, a weak peak will be observed for 1 and 1-M 2+, due to a small ratio of reversible protonation, showing that in acetonitrile 1 acts as a better MLG candidate than in water solvent. On the other hand, in acidic conditions all five species will emit and as a result, 1 will not be an AND MLG, showing that the selection of the solvent conditions is crucial for a species to act as an MLG candidate. Finally, we conclude that the retaining of emission is accomplished by the simultaneous tetrahedral geometry of all three aniline N atoms.