Two-Photon-Driven Photoprotection Mechanism in Echinenone-Functionalized Orange Carotenoid Protein.

Orange carotenoid protein (OCP) is a photoactive protein that mediates photoprotection in cyanobacteria. OCP binds different ketocarotenoid chromophores such as echinenone (ECN), 3'- hydroxyechinenone (hECN), and canthaxanthin (CAN). In the dark, OCP is in an inactive orange form known as OCP; upon illumination, a red active state is formed, referred to as OCP, that can interact with the phycobilisome.

Laser Flash Photolysis of Carbazole in Solution: Cation Radical as a Source of Carbazolyl Radical.

In the course of 266 nm nanosecond laser flash photolysis of carbazole (CBL) in acetonitrile, we discovered a new transient absorption band centered at 360 nm that has been heretofore unreported despite numerous reports on similar topics. To put some limits on possible transients responsible for this absorption band and thus to solve the mechanism of CBL photolysis, we employed the strategy of selectively blocking the CBL active sites by various modifications in the structure. This strategy was supported by the use of the solvent effect and triplet quenching by molecular oxygen.

Fast singlet excited-state deactivation pathway of flavin with a trimethoxyphenyl derivative.

Incorporation of the trimethoxyphenyl group at position 7 of flavin can drastically change the photophysical properties of flavin. We show unique fast singlet (π,π*) excited state deactivation pathway through nonadiabatic transition to the (n,π*) excited- state, and subsequent deactivation to the ground electronic state (S), closing the photocycle. This mechanism explains the exceptionally weak fluorescence and the short excited-state lifetime for the flavin trimethoxyphenyl derivative and the lack of excited triplet T state formation.

Cooperativity of ESPT and Aggregation-Induced Emission Effects-An Experimental and Theoretical Analysis of a 1,3,4-Thiadiazole Derivative.

(NTBD) was extensively studied through stationary UV-vis absorption and fluorescence measurements in various solvents and solvent mixtures and by first-principles quantum chemical calculations. It was observed that while in polar solvents (e.g.

Clicked BODIPY-Fullerene-Peptide Assemblies: Studies of Electron Transfer Processes in Self-Assembled Monolayers on Gold Surfaces.

Two BODIPY-C-peptide assemblies were synthesized by CuAAC reactions of BODIPY-C dyads and a helical peptide functionalized with a terminal alkyne group and an azide group, respectively. The helical peptide within these assemblies was functionalized at its other end by a disulfide group, allowing formation of self-assembled monolayers (SAMs) on gold surfaces. Characterizations of these SAMs, as well as those of reference molecules (BODIPY-C-alkyl, C-peptide and BODIPY-peptide), were carried out by PM-IRRAS and cyclic voltammetry.