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[C ₅NH₅]₁₄[H₁₅(Mo₂O ₄)₈Co₁₆(PO₄)₁₄(HPO ₃)₁₀(OH)₃]}·5H₂O (1) and [C₃H₅N₂]₄[C₅NH ₅]₂[Ni(H₂O)₆]{[C₃H ₄N₂]₂[C₅NH₅] ₁₄[H₁₈(Mo₂O₄)₈Ni ₁₆(PO₄)₂₂(OH)₆]}·11H ₂O (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 σ 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. This journal is