An experimental and theoretical approach to the acid–base and photophysical properties of 3-substituted β-carbolines in aqueous solutions

摘要: Abstract The photophysical properties and the acid–base equilibrium of β-carboline-3-carboxylic acid N -methylamide (βCMAM) in aqueous solution have been investigated. p K a values ground first excited state spectrophotometrically determined using Forster cycle for state. This compound methyl-β-carboline-3-carboxylate (βCCM) are most acidic β-carboline derivatives studied till now both acidity these compounds is explained terms optimised structure solvated molecules density functional method’s (DFT) computational method polarized continuum model’s (PCM) solvatation model. In contrast with gas phase calculation published on β-carbolines, this work, we included effects order to reproduce relative experimental pyridinic nitrogen proton affinities 3-subtituted β-carbolines Norharmane. calculations insufficient inclusion vital. Potential energy barrier when dihedral angle between Norharmane skeleton substituent varies also calculated elucidate importance steric hindrance 3-substituted derivatives. different neutral cationic forms βCCM βCMAM their structures.