Comparing the linear and non-linear optical properties of keto-enol forms of N-alkyl, N-aryl, and O-alkyl substituted 2-Hydroxybenzophenone

Abstract

The Geometrical, electronical, spectral, linear, and non-linear optical properties (NLO) of keto-enol forms of 2-hydroxybenzophenone (2-HBp) derivatives were examined. Ten pairs of 2-HBp derivatives having D-π-A framework with N-alkyl (ethyl, julolidine), N-aryl (phenyl), O-methyl, groups as donor, phenyl ring as aspacer, and carbonyl group linked to phenyl ring consisting of either mono or dicarboxylic acid group as acceptor, were selected. DFT results suggest thatthe keto form is stablein the S0 and S1 states. Further, IR spectra, CV analysis, experimental absorption maxima, and TD-DFT results support the existence of 2-HBp derivatives in keto form. Thermogravimetric analysis shows that 2-HBp derivatives have remarkable thermal stability (∼200 °C), enabling their practical application in NLO. Further, DFT and TD-DFT results show that theketo form of 2-HBp derivatives with lower BLA, higher μ, ω, η, Γ, and hyperpolarizability exhibits superior NLO properties compared to theenol form of 2-HBp derivatives.