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Geometry-Driven Control of Linear and Nonlinear Optical Responses in p -Nitroaniline: Insights into Structure–Property Relationships and Thermal Robustness

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The nonlinear optical (NLO) response of organic chromophores is intrinsically governed by their molecular geometry; yet, the microscopic mechanisms that link specific deformations to optical properties remain unclear. Here, we reveal how controlled torsional and bond-length distortions in p -nitroaniline (pNA) dictate its dipole moment, polarizability, and hyperpolarizabilities, establishing clear geometry–property relationships. Using density functional theory and coupled-cluster calculations combined with thermal ensemble modeling, we uncover threshold-like behaviors: NH 2 and NO 2 torsions dominate the optical response, while local vibrational displacements have negligible effects. Remarkably, ensemble-averaged properties remain stable under thermally accessible fluctuations, demonstrating the intrinsic robustness of pNA’s NLO response. These results provide fundamental physical insight into geometry-driven modulation of optical properties, offering guiding principles for the rational design of molecular photonic materials.

Source: ACS Omega

DOI: 10.1021/acsomega.5c08003

Authors: Vinicius Manzoni, Rodrigo M. Gester, Antônio R. da Cunha, Gabriel I. Pagola, Guillermo F. Quinteiro Rosen, Patricio F. Provasi