Dipolar Donor–Acceptor-Substituted Schiff Base Complexes with Large Off-Diagonal Second-Order Nonlinear Optical Tensor Components
✍ Scribed by Santo Di Bella; Ignazio Fragalà; Isabelle Ledoux; Joseph Zyss
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 131 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
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 secondharmonic 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-dimen-sional 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 ± (p-conjugate-bridge) ± acceptor system. These dipolar two-dimensional molecules are interesting candidates from the perspective of polarizationindependent NLO materials.