Six new coordination polymers, {[Ag(bpa)]·(1,4-Hndc)}_n (1), {[Ag(bpp)]·(1,4-Hndc)}_n (2), [Cd(1,4-ndc)(bpa)_0.5]_n (3), [Cd₂(1,4-ndc)₂(bpp)]_n (4), [Zn(1,4-ndc)(bpa)_0.5]_n (5) and [Co₂(H₂O)(1,4-ndc)₂(bpp)]_n (6), have been prepared under hydrothermal conditions (bpa = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane, 1,4-H₂ndc = 1,4-naphthalenedicarboxylic). All these compounds were characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction and single crystal X-ray diffraction. 1 and 2 are 1D coordination polymers. They are further linked by hydrogen-bonding interactions or Ag⋯Ag and hydrogen-bonding interactions to form a 2D (4,4) or (6,3) supramolecular network, respectively. 3 and 4 are 3D (4,5)-connected frameworks with the same structural motif. 5 comprises a 3D pcu net, and the pcu net is interpenetrated by a crystallographic equivalent net to form a two-fold interpenetrating 3D architecture. 6 exhibits a 3D 12-connected net. Thermal stability and photoluminescent properties of 1–6 were also investigated.

In this work, water- and temperature-induced single-crystal-to-single-crystal (SCSC) transformation and dissolution–recrystallization structural transformation (DRST) are observed among three new copper(II) coordination polymers, {[Cu₅(μ₃-OH)₂(MIPA)₄(4,4′-bpy)₂]·2H₂O}_n (1), {[Cu(H₂O)₂(MIPA)(4,4′-bpy)_0.5]·H₂O}_n (2) and {[Cu₂(H₂O)₂(MIPA)₂(4,4′-bpy)(μ₂-H₂O)]·3H₂O}_n (3) (MIPA = 4-methoxyisophthalic acid, 4,4′-bpy = 4,4′-bipyridine). The 3D framework of 1 experienced an intensive DRST process to form the 1D intermediate of 2, followed by a unique SCSC process to transform it into the 2D network of 3. Nevertheless, compound 3 can be obtained from compound 1 directly via another DRST. That is to say, a DRST process could be achieved by the combination of another DRST process and an SCSC process. To the best of our knowledge, this type of study is still scarce. And it provides a convenient strategy to investigate the mechanism of crystal transformation and construct advanced crystalline materials. Results have been characterized by single crystal X-ray diffraction and powder X-ray diffraction (PXRD). Significant structural alterations were observed and these changes could be analyzed from the properties of center Cu(II) ions and the switch of chelating-bridging modes of MIPA. Magnetic susceptibility measurements indicate that 1 and 3 exhibit antiferromagnetic interaction between adjacent Cu(II) centers. Additionally, complexes 1–3 have been characterized by thermogravimetric analysis and infrared and PXRD studies.

Four new zinc-based CPs for the sensitive and selective detection of Fe³⁺ and Cr₂O₇²⁻ ions.

A cadmium-based coordination polymer can produce the corresponding photoproduct via [2 + 2] cycloaddition reaction, and can detect both Fe³⁺ and Cr₂O₇²⁻ ions.

To investigate the influence of different 5-functionalized isophthalate ligands on the self-assembly and structures of Zn(II)-based coordination polymers (CPs), we selected four 5-functionalized isophthalate ligands coordinated with 4,4′-bipyridyl (bpy) and Zn(II) salt, and four new CPs, namely, {[Zn(EtOip)(bpy)]·2H₂O}_n (1), {[Zn(PrOip)(bpy)]·2H₂O}_n (2), [Zn(ⁿBuOip)(bpy)]_n (3) and [Zn(ⁿPeOip)(bpy)]_n (4) (where EtOip = 5-ethoxyisophthalate, PrOip = 5-n-propoxyisophthalate, ⁿBuOip = 5-n-butoxyisophthalate and ⁿPeOip = 5-n-pentyloxyisophthalate), were prepared under hydrothermal conditions. Moreover, we considered changing the features of the N-ligands (length), which are expected to alter the structural diversities and properties of the resultant CPs. We used 1,2-bis(4-pyridyl)ethene (bpe) to replace bpy; and obtained four new coordination polymers (CPs), namely, {[Zn(EtOip)(bpe)]·H₂O}_n (5), {[Zn(PrOip)(bpe)]·H₂O}_n (6), {[Zn(ⁿBuOip)(bpe)]·0.5DMF}_n (7) and [Zn(ⁿPeOip)(bpe)]_n (8). All of these compounds were characterized by single crystal X-ray diffraction, infrared spectroscopy, elemental analysis and powder X-ray diffraction measurements. Single-crystal X-ray analysis reveals that the structure of complexes 1–4 are very similar, although different functionalized-isophthalate ligands are employed. Complexes 5, 6 and 7 possess a two-dimensional (2D) layered structure, and the 2D framework of complexes 5 and 7 can be rationalized to be a threefold interpenetrating four-connected {4⁴·6²} topological sql network, while 6 exhibits a twofold interpenetrating 4-connected 2D framework. Compound 8 features a 6-connected 3D topology net based on a novel bimetallic unit [(Zn)₂(CO₂)₂] linked by mixed ⁿPeOip and bpe ligands. Moreover, thermal and photoluminescence properties of the synthesized complexes were also studied in detail.