Insights into Hydrogen Bonding Effect as Well as Excited State Intramolecular Proton Transfer Associated with Solvent Polarity and Atomic Electronegativity for 2-Phenyl-3-Hydroxybenzo[g]quinolone

Inspired by the excellent photochemical properties of 3-hydroxyflavone and its derivatives, in this work, the novel 2-phenyl-3-hydroxybenzo[g]quinolone (2P3HBQ) fluorophore is explored about its photo-induced behaviors. By investigating the photoexcitation characteristics in different solvents as well as the substituted atomic electronegativity (O -> S -> Se), the solvent-polarity-related and atomic-electronegativity-dependent photo-induced hydrogen bond of 2P3HBQ and its derivatives (2P3HBQ-O, 2P3HBQ-S and 2P3HBQ-Se) indicates the S-1-state hydrogen bonding interactions could be enhanced. Particularly, the nonpolar solvent environment and low atomic electronegativity substitution play large roles in strengthening hydrogen bonding effects. Charge reorganization stemming from photoexcitation, strengthening excited state hydrogen bond effects, and the intramolecular charge transfer (ICT) via frontier molecular orbitals (MOs) further reveals the excited state intramolecular proton transfer (ESIPT) tendency. Via the manner of constructing potential energy curves (PECs) with restricted optimization, we elaborate and reveal the novel solvent-polarity-regulated and the atomic-electronegativity-controlled ESIPT dynamical behaviors.