Second-order nonlinear optics in coordination chemistry: An open door towards multi-functional materials and molecular switches

International audience; Various inorganic and organometallic complexes exhibiting quadratic nonlinear optical (NLO) properties (i.e., linearly correlated to the square of the electric field E2) are reviewed. The computational approaches available for the calculation at various levels (either semi-empirical (ZINDO) or density functional theory (DFT)), and analysis of the NLO response are recalled. Metal-containing species usually offer architectures and NLO responses of greater versatility than those of the well-known “push-pull” organic chromophores. Their additional (e.g., magnetic) electronic abilities, open up access to multi-property molecular materials, an intriguing class of materials, which are presented and discussed here, in a perspective of molecular switch.