We characterize the structural and electronic changes during the photoinduced enol-keto tautomerization of 2-(2'-hydroxyphenyl)-benzothiazole (HBT) in a nonpolar solvent (tetrachloroethene). We quantify the redistribution of electronic charge and intramolecular proton translocation in real time by combining UV-pump/IR-probe spectroscopy and quantum chemical modeling. We find that the photophysi...

Human carbonic anhydrase II (HCA II), among the fastest enzymes known, catalyzes the reversible hydration of CO 2 to HCO 3 (-). The rate-limiting step of this reaction is believed to be the formation of an intramolecular water wire and transfer of a proton across the active site cavity from a zinc-bound solvent to a proton shuttling residue (His64). X-ray crystallographic studies have shown thi...

A new design strategy is described for chloride ion sensors based on suppression of excited state intramolecular proton transfer in squaramides as a fluorescence "turn on" mechanism.

Excited-state proton transfer has been hypothesized as a mechanism for UV energy dissipation in eumelanin skin pigments. By using time-resolved fluorescence spectroscopy, we show that the previously proposed, but unresolved, excited-state intramolecular proton transfer (ESIPT) of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) occurs with a time constant of 300 fs in ...

The mechanism for the dual emission of 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-c]pyridine (DMAPIP-c) in protic solvents was investigated by synthesizing and studying its analogues. Theoretical calculations were carried out to corroborate the experimental findings. The deprotonation studies suggest that the enhancement in the TICT emission of anionic forms of DMAPIP-c is limited to a protic en...

The excited state intramolecular proton transfer (ESIPT) mechanisms of 2-(2-hydroxyphenyl)benzoxazole (HBO), bis-2,5-(2-benzoxazolyl)-hydroquinone (BBHQ) and 2,5-bis(5'-tert-butyl-benzoxazol-2'-yl)hydroquinone (DHBO) have been investigated using time-dependent density functional theory (TDDFT). The calculated vertical excitation energies based on the TDDFT method reproduced the experimental abs...

Hydrogen bonds are important in supramolecular chemistry and responsible for proton transfer processes. This manuscript reports new hydrogen-bonding systems of redox-active acid-base assemblies consisting of dimethylthio-tetrathiafulvalene dicarboxylic acid (H(2)L) coupled with pyridine (py), 2,2'-bipyridine (2,2'-bpy), and 4,4'-bipyridine (4,4'-bpy). The (1)H NMR chemical shifts of the pyridin...

We report on the steady-state, picosecond and femtosecond time-resolved studies of a charge and proton transfer dye 6-amino-2-(2'-hydroxyphenyl)benzoxazole (6A-HBO) and its methylated derivative 6-amino-2-(2'-methoxyphenyl)benzoxazole (6A-MBO), in different solvents. With femtosecond resolution and comparison with the photobehaviour of 6A-MBO, we demonstrate for 6A-HBO in solution, the photopro...

Aggregation-induced emission enhancement (AIEE) phenomenon is observed in the polycyclic aromatic alkaloid derivatives due to the configuration changes in the excited state, which is attributed to intramolecular proton-transfer and the formation of a new structure of enol form.

The formation of two-component molecular cocrystals can lead to the tunable excited state intramolecular proton transfer (ESIPT) process and emission, as first confirmed by both experimental and computational studies.