Quantum Chemical Study Of Structure, Bonding Characters And Nonlinear Optical Properties Of [XW₅O₁₈]^3-(X=Zr Or Ti)Derivatives

Various classes of molecules have been explored in terms of novel molecular NLO materials.There are three generic classes of NLO materials:inorganic salts,organic materials and organometallic materials.Each class possesses its own complement of favorable and unfavorable attributes for NLO application.but the NLO performance of such materials is not satisfactory.The NLO responses of organic compounds often exceed those of purely inorganic substances,but organic materials suffer several disadvantages which limit the applicability of such materials.For example,usually they have very poor thermal stability and (in poled guest-host systems) they may undergo a facile relaxation to random orientation.The limitations identified above have stimulated much research into the NLO properties of various alternative materials,among which organometallic complexes are of particular interest because of its potential for combining the advantages of both organic and inorganic materials.9-16 The study of organometallic complexes with NLO properties has produced a number of publications.However,science is without limits.The search for new molecular with noble second-order nonlinear optical properties has never stopped.Since the pioneering work of Likai Yan and her coworkers.who for the first time investigated the NLO properties of organoimido derivatives of hexamolybdates,some effort has been directed toward a comprehensive understanding of the NLO properties of POM-based organic-inorganic materials.We report a theoretical study based on DFT and TDDFT calculations on the bonding nature,first hyperpolarizabilities,electronic transition and charge transfer involved in nonlinear optical response of aryloxide and salicylaldehyde derivatives of[XW₅O₁₈]^3-(whereas X=Zr or Ti).NBO analysis reveal that there exist two different kinds ofÏ€-interactions regarding OL atom in our studied systems.Second,in our studied systems the differences in molecular composition is very slight.However,theβ₀ values differ significantly.This variation can be traced to the different electronic transition and charge transfer characteristics.The heteropolyanion cluster and organic ligand are both electron-rich groups.A small change in molecular composition will cause a "butterfly effect" upon NLO properties.