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(H 2 O) 6 ]{[C 3 H 4 N 2 ] 2 [C 5 NH 5 ] 14 [H 15 (Mo 2 O 4 ) 8 Co 16 (PO 4 ) 14 (HPO 3 ) 10 (OH) 3 ]}·5H 2 O ( 1 ) and [C 3 H 5 N 2 ] 4 [C 5 NH 5 ] 2 [Ni(H 2 O) 6 ]{[C 3 H 4 N 2 ] 2 [C 5 NH 5 ] 14 [H 18 (Mo 2 O 4 ) 8 Ni 16 (PO 4 ) 22 (OH) 6 ]}·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 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.