A theoretical assignment on excited‐state intramolecular proton transfer mechanism for quercetin

摘要: In the present work, we investigate a new chromophore (ie, quercetin) (Simkovitch et al J Phys Chem B 119 [2015] 10244) about its complex excited-state intramolecular proton transfer (ESIPT) process based on density functional theory and time-dependent methods. On basis of calculation electron rho(r) Laplacian del(2)rho(r) at bond critical point using atoms-in-molecule theory, hydrogen bonds (O-1-H2 center dot O5 O-3-H4 O5) have been supported to be formed in S-0 state. Comparing prime structural variations quercetin involved 2 bonds, find that these should strengthened S-1 state, which is fundamental precondition for facilitating ESIPT process. Concomitantly, infrared vibrational spectra analysis further verifies this viewpoint. good agreement with previous experimental results, reveals kinds structures (quercetin* quercetin-PT1*) Frontier molecular orbitals depict nature electronically excited state support reaction. Our scanned potential energy curves according variational O-1-H-2 O-3-H-4 coordinates demonstrate more likely occur via wire O-1-H2 rather than because lower barrier 2.3kcal/mol. work explains result makes up deficiency mechanism experiment. end, make reasonable assignment quercetin.