Hydrogen bond effects in the ground and excited singlet states of 4H-1-benzopyrane-4-thione in water—theory and experiment

Abstract

The hydrogen bond energies for 4H-1-benzopyrane-4-thione (BPT) in its ground and two lowest excited singlet electronic states have been determined using ab initio methods. It was shown that the BPT molecule can form, as an acceptor, four relatively strong hydrogen bonds with water molecules, leading to a stable complex in the ground electronic state S(0). The hydrogen bonds involving the sulfur atom from the thiocarbonyl group were found to be stronger than those involving the oxygen atom from the benzopyran moiety. The former hydrogen bonds were predicted to become significantly weaker upon excitation to the S(1) state and, in contrast, stronger upon excitation to the S(2) state. Calculated changes in the hydrogen bond energy due to the S(0)→ S(1) and S(0)→ S(2) excitation are in very good agreement with the experimental values obtained from the absorption solvatochromic study, according to a procedure proposed by us in [E. Krystkowiak, et al., J. Photochem. Photobiol. A: Chem., 2006, 184, 250]. The maxima of absorption spectra of the BPT-water hydrogen-bonded complex, calculated taking into consideration nonspecific solute-solvent interactions, are also in good agreement with the experimental results.

Structural and optical properties of short peptides: nanotubes‐to‐nanofibers phase transformation

“…It allows suggesting a possible mechanism for the change of their optical properties. Hydrogen bonds are known to affect the band gap of molecular complexes in both inorganic and organic nano‐assemblies . It was shown that interaction of a complex of the form A‐H–OH‐B can cause ionic and electronic rearrangement in both A and B upon excitation and can affect dramatically the bandgap as a function of the hydrogen bond strength.…”

Photophysics, Excited‐state Double‐Proton Transfer and Hydrogen‐bonding Properties of 5‐Deazaalloxazines

“…We previously used similar way to determine energy of complexes formed between lumichrome (7,8‐dimethylalloxazine) and methanol or acetic acid . To calculate the hydrogen bond energy postulated in the ground and first excited singlet state, we used a model proposed by Krystkowiak and others for 4H‐1‐benzopyrane‐4‐thione (BPT) .…”

Deactivation of 6-Aminocoumarin Intramolecular Charge Transfer Excited State through Hydrogen Bonding

“…The procedure for independent and accurate determination of excitation or deactivation induced changes in the energy of nonspecific interactions and changes in the energy of particular types of hydrogen bonds proposed by us in [ 1 ] has been applied in this paper (as well as in [ 3 , 5 , 70 ]) for investigation of spectral and photophysical properties of 6AC and the complexes it makes with solvent molecules. The main aim of the study was to establish the effect of solute–solvent hydrogen bonds on the absorption and emission spectral properties and deactivation processes.…”