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

Abstract

Divalent 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.

Post-Synthetic Functionalization of Ni-MOF by Eu3+ Ions: Luminescent Probe for Aspartic Acid and Magnetic Property

“…The Ni–OCO–Ni carboxylate bridges with syn–syn conformation, long separation (3.49 Å) between Ni­(II) centers, as well as large Ni–O–Ni angle (122.91°) in oxo-bridged Ni­(II) clusters lead to the antiferromagnetic phenomenon in 1 . The analogous magnetic behaviors were previously observed in dinuclear-based compounds [Ni 2 (adc) 2 (μ-H 2 O)­(4-bpfh) 2 ] n and {[Ni 2 (tdc) 2 (bpfh) 2 (H 2 O)]·2H 2 O} n . , The χ M data could be analyzed as dinuclear Ni­(II) units by eqs and . , The fitting g , J , and zJ′ parameters are 2.16, 0.50 cm –1 , and −0.15 cm –1 , respectively, which are in the expected range for weak magnetic exchange within dinuclear Ni­(II) centers …”

“…55 Moreover, the magnetic transferring is related to the angle between Ni(II) centers and the bridging H 2 O. 56 57,58 The χ M data could be analyzed as dinuclear Ni(II) units by eqs 1 and 2. 59,60 The fitting g, J, and zJ′ parameters are 2.16, 0.50 cm −1 , and −0.15 cm −1 , respectively, which are in the expected range for weak magnetic exchange within dinuclear Ni(II) centers.…”