Three ZnII Coordination Polymers Based on 1,2-Naphthalenedicarboxylate and Different 4,4′-Bipyridyl-like Bridging Co-ligands: Structural Regulation and Properties

Abstract

Three new ZnII coordination polymers, namely [Zn(ndc)]n (1), {[Zn(ndc)(bpe)]·1.25H2O}n (2), and {[Zn(ndc)(bpee)]·1.25H2O}n (3), were prepared based on in situ reaction of 1,2-naphthalenedicarboxylic anhydride (ndca) with two different 4,4′-bipyridyl-like bridging co-ligands, bpe and bpee (ndc = 1,2-naphthalenedicarboxylate, bpe = 1,2-bis(4-pyridyl)ethane, and bpee = trans-1,2-bis(4-pyridyl)ethylene). In 1, the ZnII and ndc ligands are directly involved in the polymeric frameworks, forming a 2D (43.63) layered network. Complexes 2 and 3 similarly consist of Zn2(ndc)2 binuclear units that are linked by bpe and bpee ligands, respectively, into a 2D (44.62) sheet. However, further analysis indicates that 2 and 3 feature the similar 2-fold interpenetrating structure linked via hydrogen bonding interactions for 2 and aromatic stacking interactions for 3. In addition, the resultant 2D→3D supramolecular frameworks of 2 and 3 are both constructed via aromatic stacking interactions. Also, the fluorescent and thermal properties of the complexes were investigated.