Prediction of NLO response of substituted organoimido hexamolybedate: First theoretical framework based on p-anisidine adduct [Mo6O18(p-MeOC6H4N)]2-

Abstract

The second-order nonlinear optical (NLO) responses and dipole polarizabilities of p-anisidine adduct (imido derivative of hexamolybdates/polyoxometalates/POMs/Cluster) are studied by means of time dependent density functional (TDDFT) calculations. A substantial molecular second-order NLO response has been noticed in these organic-inorganic hybrid compounds, particularly [Mo6O17 cis-(p-MeOC6H4N)2]2− (system 2) and [Mo6O18 p-MeOC6H4N]2- (system 1) having static second-order polarizability (βvec) calculated to be 1949.60 au and 1565.10 au respectively. Both p-anisidine and cis-(p-anisidine) are found to be preferred choice over the trans-(p-anisidine) adduct. There is a fair probability for these systems to be selected as efficient second-order nonlinear optical materials. The movement of charge transfer from p-anisidine to hexamolybdate cluster (D–A) along the y-axis suggests molybdenum cluster acts as an acceptor (A) whereas p-anisidine working as a donor (D) in all the studied systems which is responsible for NLO response in such adducts. An incremental increase in the computed βvec values were evaluated by incorporation of an electron donor (Metalloporphyrin) instead of p-anisidine. Furthermore, substitution of Fe over Zn in Metalloporphyrin cage has enhanced the optical nonlinearity. This research effort offers a significant understanding into metal (Fe/Zn) to metal (Mo) charge transfer through imido-linkage in hexamolybdates, which has been found to be an efficient mode to enhance NLO response as a prime example in modulation of optoelectronics.