Divalent Metal 2,5‐Thiophenedicarboxylate Coordination Polymers with the Conformationally Flexible Bis(4‐pyridyl­formyl)homopiperazine Ligand

Abstract

AbstractDivalent metal coordination polymers containing the rigid 2,5‐thiophenedicarboxylate (tdc) ligand and the conformationally flexible dipyridylamide ligand bis(4‐pyridylformyl)homopiperazine (bpfh) show different layer topologies and chirality. As determined by single‐crystal X‐ray diffraction, {[Cd(tdc)(bpfh)(H2O)]·3H2O}n (1) shows a twofold parallel interpenetrated centrosymmetric (4,4) layered grid structure. {[Zn(tdc)(bpfh)]·H2O}n (2) exhibits a similar system of twofold interpenetrated (4,4) grid‐like layers, but in contrast to 1, it crystallizes in an acentric space group. {[Ni2(tdc)2(bpfh)2(H2O)]·2H2O}n (3) possesses {Ni2(μ‐H2O)(OCO)2} dimeric units connected into a doubled layer motif by the full span of the tdc and bpfh ligands. Weak antiferromagnetic coupling is observed within the dimeric units in 3 [g = 2.172(6) and J = –0.79(1) cm–1]. Compounds 1 and 2 undergo blue‐violet fluorescence upon ultraviolet irradiation; the cadmium derivative 1 shows potential as a sensor for the solution‐phase detection of nitrobenzene although coordination polymer exfoliation likely occurs. Thermal decomposition behavior of the three new phases is also discussed.