Schiff base coordination flexibility toward binary cobalt and ternary zinc complex assemblies. The case of the hexadentate ligand N,N′-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine

Piperazine-based Schiff base N,N′-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine, H2L(1), upon reaction with Co(II)/Zn(II) afforded discrete binary-ternary [Co(L)]3(ClO4)3.4H2O(2) and [Zn2(L)(CH3COO)2](3) assemblies. X-ray and spectroscopic studies suggest that H2L conformational flexibility, molecular stoichiometry, and bulk constraints (a) play a crucial role in mononuclear-dinuclear M-L complex assembly, and (b) determine electronic-structural-optical properties key to development of advanced materials.