Insights into the linear and non-linear optical characteristics of substituted bi-naphthyl-2-pyrazolines

Abstract

Donor/acceptor substitutions of a series of naphthyl bi-substituted 2-pyrazolines at accurate positions leads to large variations of their optical properties. An insightful discussion, supported by theoretical density functional theory (DFT) calculations, is presented on how the intrinsic polarization of the 2-pyrazoline core influences dipole moment, charge transfer, and optical properties, with distinct patterns based on substituent attachment enhancing either second or third harmonic generation. In particular, this study highlights the importance of the juxtaposition of electron-releasing sub-units within small molecules for modulating their second and third-order susceptibilities in PMMA films. The DFT calculations corroborated these experimental findings, underscoring the importance of substituent effects, enriching our understanding and enabling the development of novel materials with customizable optical functions.