Nonlinear molecular quadratic hyperpolarizabilities

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. 

Di Bella. S.. Marks, T.J., Ratner, M.A. Environmental elects on nonlinear optical chromophore performance. Calculation of molecular quadratic hyperpolarizabilities in solvating media. J. Am. Chem. Soc. 116, 4440-4445 (1994)... 

Naulty, R.H., McDonagh, A.M., Whittall, I.R., Cifuentes, M.P., Humphrey, M.G., Houbrechts, S., Maes, J., Persoons, A., Heath, G.A., Hockless, D.C.R. Organometalhc complexes for nonlinear optics. 15. Molecular quadratic hyperpolarizabilities of trans-bis bis(diphenylphosphino)methane]ruthenium cr-aryl- and cr-pyridyl-acetyhdes x-ray crystal structure of trans-[Ru(2-C=CC5H3N-5-NO2)Cl(dppm)2]. J. Organomet. Chem. 563, 137-146 (1998)... 

I. D. L. Albert, S. di Bella, D. R. Kanis, T. J. Marks, and M. A. Ratner, in Polymers for Second-Order Nonlinear Optics, American Chemical Society, Washington, DC, 1995, pp. 57-65. Solvent Effects on the Molecular Quadratic Hyperpolarizabilities. 

Nonlinear optical properties depend upon the molecular environment as well as the individual molecular prop erties. In particular, at the molecular level, second harmonic generation depends upon the magnitude of p (the quadratic hyperpolarizability), which is the coefficient... 

Coe, B.J., Houbrechts, S., Asselberghs. I.. Persoons. A. Efficient, reversible redox-switching of molecular first hyperpolarizabilities in ruthenium(II) complexes possessing large quadratic optical nonlinearities. Angew. Chem. Int. Ed. 38. 366-369 (1999)... 

This work provides a relatively comprehensive review of studies involving ruthenium coordination and organometallic complexes as nonlinear optical (NLO) compounds/materials, including both quadratic (second-order) and cubic (third-order) effects, as well as dipolar and octupolar chromophores. Such complexes can display very large molecular NLO responses, as characterised by hyperpolarizabilities, and bulk effects such as second harmonic generation have also been observed in some instances. The great diversity of ruthenium chemistry provides an unparalleled variety of chromophoric structures, and facile Ru" —> Ru" redox processes can allow reversible and very effective switching of both quadratic and cubic NLO effects... 

---