Structural Diversity in Luminescent Three-Dimensional Cadmium Aliphatic Dicarboxylate Coordination Polymers Incorporating 4,4′-Dipyridylamine: Interpenetrated, Non-Interpenetrated, and Self-Penetrated Networks

Three cadmium coordination polymers incorporating both a flexible aliphatic α,ω-dicarboxylate and the hydrogen-bonding capable diimine 4,4′-dipyridylamine (dpa) have been prepared and structurally characterized. {[Cd(adp)(dpa)]}n (1, adp = adipate) adopts a doubly interpenetrated decorated primitive cubic three-dimensional (3D) coordination polymer network. {[Cd7(pim)6(dpa)6(H2O)2](ClO4)2·6H2O}n (2, pim = pimelate) exhibits a complex (8,10)-connected binodal self-penetrated cationic 3D network with (384145462)(31041851463) topology constructed from the linkage of oligomeric {Cd7(dpa)6(H2O)2}14+ secondary building units through pimelate ligands with different conformations. To the best of our knowledge, this is the highest-connected binodal self-penetrated lattice reported to date. Extending the length of the α,ω-dicarboxylate resulted in a CdSO4-type (658 topology) 4-connected 3D network in {[Cd(sub)(dpa)]·2H2O}n (3, sub = suberate). The length of the polymethylene unit within the dicarboxylate ligand, the coordination preferences at cadmium and anion inclusion, together with dpa-mediated hydrogen bonding, exert a cooperative structure directing effect in this system. All three coordination polymers undergo blue-violet luminescence under ultraviolet irradiation.