Coordination and Organometallic Complexes as Second-Order Nonlinear Optical Molecular Materials

Coordination and organometallic complexes with second-order nonlinear optical (NLO) properties have attracted increasing attention as potential mol. building block materials for optical communications, optical data processing and storage, or electrooptical devices. In particular, they can offer addnl. flexibility, when compared to org. chromophores, due to the presence of metal-ligand charge-transfer transitions, usually at relatively low-energy and of high intensity, tunable by virtue of the nature, oxidn. state, and coordination sphere of the metal center. This chapter presents an overview of the main classes of second-order NLO coordination and organometallic complexes with various ligands such as substituted amines, pyridines, stilbazoles, chelating ligands (bipyridines, phenanthrolines, terpyridines, Schiff bases), alkynyl, vinylidene, and cyclometallated ligands, macrocyclic ligands (porphyrins and phthalocyanines), metallocene derivs., and chromophores with two metal centers. The coverage, mainly from 2000 up to now, is focused on NLO properties measured at mol. level from soln. studies, as well as on NLO properties of bulk materials.