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Dipolar Donor–Acceptor‐Substituted Schiff Base Complexes with Large Off‐Diagonal Second‐Order Nonlinear Optical Tensor Components
Author(s) -
Di Bella Santo,
Fragalà Ignazio,
Ledoux Isabelle,
Zyss Joseph
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010903)7:17<3738::aid-chem3738>3.0.co;2-i
Subject(s) - hyperpolarizability , dipole , second harmonic generation , tensor (intrinsic definition) , acceptor , molecular physics , diagonal , chemistry , molecule , materials science , condensed matter physics , physics , optics , polarizability , mathematics , geometry , organic chemistry , laser , pure mathematics
The synthesis, characterization, and two‐dimensional second‐order nonlinear optical (NLO) response of a dipolar Ni II donor–acceptor Schiff base complex and the related ligand are reported. Electric‐field‐induced second‐harmonic generation and harmonic light (hyper‐Rayleigh) scattering techniques, in combination with INDO/SCI‐SOS theoretical calculations, were used to investigate the vector part of the hyperpolarizability tensor and the two‐dimensional character of the molecular nonlinearity, respectively. Off‐diagonal hyperpolarizability tensors can be related to charge‐transfer transitions that are polarized perpendicular to the molecular dipolar axis, while parallel transitions account for the diagonal hyperpolarizability tensor. The role of the metal center in enhancing the two‐dimensional NLO response of such molecules is twofold since it acts both as the donor and the bridging moiety of the planar donor–(π‐conjugate‐bridge)–acceptor system. These dipolar two‐dimensional molecules are interesting candidates from the perspective of polarization‐independent NLO materials.