How do the different defect structures and element substitutions affect the nonlinear optical properties of lacunary Keggin polyoxometalates? A DFT study

摘要

Systematic DFT calculations have been carried out on the lacunary alpha-Keggin polyoxometalate derivatives [PW11O39](7-), [XW9O34](n-) (X = Al-III, Si-IV, Ge-IV, P-V, As-V, and Sb-V), [XW9M2O39](n-), and [XW9M3O40](n-) (X = P-V and Si-IV, M = Mo-VI, V-V, Nb-V, and Ta-V) to investigate the geometric structure and element substitution effects on the molecular nonlinear optical response. Analysis of the computed static second-order polarizability (beta(0)) predicts that the molecular nonlinear optical activity of lacunary Keggin polyoxometalate derivatives can be modified by replacing the central heteroatom and the addenda metal atom. Substitution of the central Al atom or the addenda V atom causes significant enhancement in the molecular nonlinearity. Moreover, the beta(0) values are substantially dependent on the defect structures. This class of inorganic complexes possesses remarkably large molecular optical nonlinearity, especially for the partial substitution complex [SiW9Nb2O39](10-) (IIIc), which has a computed beta(0) value of 2071.0 a.u. Thus, lacunary Keggin polyoxometalates could become excellent candidates in the field of second-order NLO. (c) Wiley-VCH Verlag GmbH & Co.