Second octupolar organic molecules

LeBozec and co-workers have reported nonlinear behavior in a series ofterpyri-dyl and dipicolinic acid complexes, with further studies on these complexes by Maury and co-workers [83, 84]. Their research was on new molecular materials for optoelectronics, with studies based on octupolar nonlinear optical molecules showing that molecular quadratic hyperpolarizability values were strongly influenced by the symmetry of the complexes [85]. Other studies on organic-lanthanide complexes with nonlinear optics have also reported second- and third-harmonic generation behavior with simultaneous multiphoton absorption properties [50]. Such studies have shown the importance of coordination chemistry as a versatile tool in the design of nonlinear materials. 

Ray reviews some recent developments concerning the design of novel materials with large NLO effects. He considers a series of organic salts and various organometallic derivatives where it was found that metal-to-ligand charge-transfer has a dominant contribution to the second-order NLO response. He also discusses the first hyperpolarizability of several retinal derivatives, ionic octupolar molecules and zwitterionic derivativatives. Solvent effects on NLO properties are also reviewed. 

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