Energy of the CH⋯O H-bonds and others specific contacts in the quercetin molecule: QM/QTAIM approximation formulas

Abstract

Quercetin molecule is known to be a natural flavonoid with a wide set of biological functions, such as anti-oxidant, anti-inflammatory, anti-hypertensive, vasodilator effects, anti-viral, anti-obesity, anti-hypercholesterolemic, anti-atherosclerotic activities, tissue regeneration and so on. Based on the results of the quantum-mechanical modeling of the tautomeric and conformational properties of the legendary quercetin molecule (Brovarets' & Hovorun, 2019–2020), it was analyzed in details and generalized main physico-chemical properties of the intramolecular specific interactions: OH⋯OH, OH⋯C, OH⋯CH, OH⋯HC, CH⋯O, CH⋯OH, HCH⋯O and HCH⋯OH H-bonds and O⋯O and O⋯C attractive van der Waals contacts. For the first time it was received approximation formulas for the estimation of the energy of these interactions based on their electron-topological and geometrical characteristics, in particular: EOH⋯O = 239.03·ρ-3.09; EOH⋯OH = 238.99·ρ-3.09; EOH⋯CH = 222.36·ρ-0.40; ECH⋯O = 245.91·ρ-0.15; ECH⋯OH = 250.93·ρ-0.56; EHCH⋯O = 250.8·ρ-0.6; EO⋯O = 218.84·ρ-0.32 and EO⋯C = 215.91·ρ-0.29 (E – energy, kcal·mol-1; ρ – electron density, a.u.). Presented formulas enable researchers to apply them for the molecular structures of different origin.