Two novel organic-inorganic hybrid molybdenum(v) cobalt/nickel phosphate compounds based on isolated nanosized Mo/Co((Ni)/P cluster wheels

Two high-nuclear wheel-shaped nanoscale clusters, [Co(H2O)(6)]{[C3H4N2](2)[C5NH5](14)[H-15(Mo2O4)(8)Co-16(PO4)(14)(HPO3)(10)(OH)(3)]}center dot 5H(2)O (1) and [C3H5N2](4)[C5NH5](2)[Ni(H2O)(6){[C3H4N2](2)[C5NH5](14)[H-18(Mo2O4)(8)Ni-16(PO4)(22)(OH)(6)]}center dot 11H(2)O (2), have been successfully synthesized employing the Py and Imi ligands as chemical modifiers. Both clusters take nanoscale wheel-like shapes, and the inorganic cores are wrapped up by the Py and Imi ligands acting as organic shells. In compounds 1 and 2, the polyoxoanion unit exhibits a new organic-inorganic hybrid polymolybdophosphate, representing the first two isolated POMs in the wheel-type {Mo/TM/P} materials, while Py and Imi ligands improve electric the delocalization effects of polyanions. It is worth noting that the molecular TPA cross section sigma of compound 1 is 2.5 times that of compound 2, which demonstrates that the nonlinear optical property can also be improved by replacing part of the phosphate radicals with phosphite radicals through enhancing electron delocalization.