The comparative investigation on redox property and second-order nonlinear response of Keggin-type α-[PM12O39NPh]3? (M = W and Mo) and Mo6NPh

Keggin-type phenylimido-polyoxometalates α-PM12O39NPh]3 (M = W and Mo) have been systematically investigated on the electronic structures, redox as well as nonlinear optical (NLO) properties by density functional theory (DFT). The strong M≡N bond confirmed by natural bond orbital (NBO) analysis comprises one s bond and two π bonds, the same as Mo≡N in Mo6O18NPh]2 . Furthermore, phenylimido segment effectively modifies the electronic properties of α-PM12O39NPh]3 . On one hand, when enlarging the inorganic cluster from {Mo6O18} to {PMo12O39}, the energy gap between HOMO and LUMO in α-PMo12O39NPh]3 decreased, resulting in enormously anodic shift for the reduction potential, while the excitation energy is less and the total second-order polarizability β 0 is up to 438-3×10 30 esu, which is nearly 10 times larger than that of Mo6O18NPh]2 . On the other hand, when metal W in α-PM12O39NPh]3 is substituted by Mo, the interaction between Mo and N is enhanced and the redox ability becomes stronger. The β 0 value for α-PMo12O39NPh]3 is more than 5 times higher than that of α-PW12O39NPh]3 . It indicates that changing appropriate metal or enlarging the inorganic cluster will improve the redox properties and second-order nonlinear response. Moreover, the electron transition for three compounds mentioned above occurred mainly from organoimido segment (as the electron donor) to polyanion cluster (as the acceptor). As a result, α-PMo12O39NPh]3 may be a promising candidate for oxidant and nonlinear optical material. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. Supported by National Natural Science Foundation of China (Grant No. 20573016), Training Fund of NENU’s Scientific Innovation Project (Grant No. NENUSTC07017), Science Foundation for Young Teachers of Northeast Normal University (Grant No. 20070304) and Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT)