Insights into photo-induced excited state intramolecular proton transfer behavior for the novel 2-([1, 1'-biphenyl]-4-yl)-3-hydroxy-4H-chromen-4-one system: Effects of solvent polarity

In the light of potential applications for detecting cysteine in vitro and in vivo, 2-([1, 1'-biphenyl]-4-yl)-3-hydroxy-4H-chromen-4-one (B-bph-fla-OH) is explored about its excited state behaviors. Solvent-polarity-related photo-induced hydrogen bond of B-bph-fla-OH indicates nonpolar aprotic solvents largely enhance S-1-state hydrogen bonding interactions. Charge reorganization stemming from photoexcitation and polarity-dependent energy gap between HOMO and LUMO orbitals further reveals the excited state intramolecular proton transfer (ESIPT) tendency. Insights into potential energy curves along ESIPT paths in solvents with different polarities and emission spectral behaviors of proton-transfer tautomer, we present solvent polarity could harness the excited state behaviors for B-bph-fla-OH system.