A series of novel zinc(ii) entangled coordination polymers based on carboxyphenyl-terpyridine ligands

摘要

Hydrothermal synthesis has afforded five divalent zinc coordination polymers containing 4-(4-carboxyphenyl)-2,2′:6′,2′′- terpyridine (HL_1) or its isomer 4-(4-carboxyphenyl)-2,2′: 4′,4′′-terpyridine (HL_2), with or without the addition of auxiliary ligands, 1,3,5-benzenetricarboxylic acid (H _3btc) and 1,4-benzenedicarboxylic acid (H_2bdc). Their structures have been characterized by single crystal X-ray analyses and further characterized by infrared spectra, elemental analyses, powder X-ray diffraction, thermogravimetric analyses and photoluminescent spectra. Across this series, the π?π interactions have a dramatic impact on the self-assembly of these entanglement structures, in either case it can exert an important structure-directing role. In addition, the disposition of pyridine nitrogen atoms in ligands also plays a large role in structure direction in this system. Complex 1 is a 2D + 2D→3D inclined polycatenated coordination polymer based on the resulting array of 2D (6,3) layers constructed by 1D→2D π?π directed self-assembly. Complex 2 is assembled into a 3D framework by means of 1D + 1D→3D mutual interdigitation based on 1D→1D self-assembly driven by π?π stacking interactions. Complex 3 shows a 2D + 2D→3D interdigital network involving 2D + 2D→2D parallel interpenetrated and 2D + 2D→2D interdigital (4,4) layer motifs. Complex 4 displays a 2D + 2D→3D polythreaded framework based on a 2D (4,4) network comprised of alternating rings and rods. Complex 5 is a (3,4)-connected 3D framework with topology (4.8~2.10~3)(4.8~2). In comparison with covalently connected entanglements, such π?π directing self-assembly of entanglements are far less explored, especially, polycatenane based on 1D chain motifs and polythread based on 2D layer motifs are rarely reported. Furthermore, the luminescent properties of complexes 1-5 at room temperature have also been studied in detail herein. This journal is