Zinc and cadmium flexible-arm ortho-dicarboxylate bis(pyridyl)piperazine coordination polymers with rare two- and three-dimensional topologies

Hydrothermal reaction of a d¹⁰ configuration divalent metal precursor with flexible-arm aromatic ortho-dicarboxylates and a bis(pyridyl)piperazine-type neutral co-ligand has generated four coordination polymers, some with rare topologies. {[Cd(hmph)(4-bpmp)_1.5]·4H₂O}_n (1, hmph = homophthalate, 4-bpmp = bis(4-pyridylmethyl)piperazine) manifests a new 3-fold interpenetrated uninodal 5-connected 3-D net with a very simple 4⁴6⁶ topology, different from the usual sqp 5-connected topology. [Cd₂(hmph)₂(4-bpfp)]_n (2, 4-bpfp = bis(4-pyridylformyl)piperazine) displays a rare 4,5-connected binodal tcs net with (4⁴6²)(4⁴6⁶) topology. [Zn₂(1,2-phda)₂(4-bpmp)(H₂O)₂]_n (3, 1,2-phda = 1,2-phenylenediacetate) possesses an uncommon 3,4-connected binodal 2-D layer with (4²6)(4²6³8) (V₂O₅ prototype) topology. [Zn₂(hmph)₂(4-bpfp)]_n (4) has a decorated (4,4) grid topology with embedded [Zn₂(OCO)₄] paddlewheel clusters. All materials exhibit ligand-centered fluorescent behavior. Thermal degradation behavior of the 3-D network materials is reported.     

Novel topological nets of lanthanide metal-organic frameworks based on dicarboxylate ligands

Four novel topological nets of lanthanide metal-organic frameworks: [Sm₂(op)₃(H₂O)]_n (1), {Ln₂(op)₂(ox)(H₂O)₄] · H₂O}_n (Ln = La, 2; Sm, 3), {[La₂(mp)₂(ox)(H₂O)₄] · 2H₂O}_n (4), [La₂(op)₂(mp)(H₂O)₄]_n (5) (op = o-phthalate, mp = m-phthalate, and ox = oxalate), have been hydrothermally synthesized and characterized. Compound 1 exhibits novel (3,4,5,6)-connected five-nodal two-dimensional net, compound 2 and 3 show the (3,4)-connected V₂O₅ topologies, compound 4 has the (4,5)-connected topological net, and compound 5 shows the (4,5)-connected four-nodal three-dimensional network. Photoluminescent analyses of 1 and 3 show strong blue emission in the solid state at room temperature.     

Synthesis and structures of zinc complexes with new binucleating ligands containing alkoxide bridges, and their activities in the hydrolysis of tris(p-nitrophenyl)phosphate

Four new binucleating ligands featuring a hydroxytrimethylene linker between two coordination sites (1,3-bis{N-[3-(dimethylamino)propyl]-N-methylamino}propan-2-ol, HL¹; 1,3-bis{N-[2-(dimethylamino)ethyl]-N-methylamino}propan-2-ol, HL²; 1,3-bis[bis(2-methoxyethyl)amino]propan-2-ol, HL³; and 1-bis[(2-methoxyethyl)amino]-3-{N-[2-(dimethylamino)ethyl]-N-methylamino}propan-2-ol, HL⁴) were synthesized, along with the corresponding zinc complexes. The structures of three dinuclear zinc complexes ([Zn₂L¹(μ-CH₃COO)₂]BPh₄ (1), [Zn₂L³(μ-CH₃COO)₂]BPh₄ (3), and [Zn₂L⁴(μ-CH₃COO)(CH₃COO)(EtOH)]BPh₄ (4)) and a tetranuclear zinc complex ({[Zn₂L²(μ-CH₃COO)]₂(μ-OH)₂}(BPh₄)₂ (2)) were revealed by X-ray crystallography. Hydrolysis of tris(p-nitrophenyl)phosphate (TNP) by these zinc complexes in an acetonitrile solution containing 5% Tris buffer (pH 8.0) at 30 °C was investigated spectrophotometrically and by ³¹P NMR. Although zinc complexes 1, 3, and 4 did not show hydrolysis activity, the tetranuclear zinc complex 2, containing μ-hydroxo bridges, was capable of hydrolyzing TNP. This suggests that the hydroxide moiety in the complex may have an important role in the hydrolysis reaction.     

Structural diversity, photoluminescence and magnet properties of complexes based on a V-shaped polycarboxylate

The self-assembly of a V-shaped ligand 3,3′,4,4′-diphenylsulfonetetracarboxylate (dstc) and metal salts in the presence of a series of N-donor ligands yielded four new complexes, namely, [Cu₄(H₂dstc)₄(phen)₄]·12H₂O (1), {[Cu₂(dstc)(bpe)(H₂O)₂]·4H₂O}_n (2), [Cu₃(dstc)(bipy)(μ₂-OH)₂(H₂O)₂]_n (3), {[Cd₅(dstc)₂(bipy)₂(μ₃-OH)₂(H₂O)₄]·4H₂O}_n (4) (phen = 1,10-phenanthroline; bpe = 1,2-bis(4-pyridyl)ethene; bipy = 4,4′-bipyridine). All the complexes were structurally determined by single-crystal X-ray diffraction and characterized by elemental analyses, IR spectra, X-ray powder diffraction and TG analyses. Complex 1 is a discrete tetranuclear unit, which further assembles into a 3D supramolecular framework by intermolecular hydrogen bonding interactions. Complex 2 is composed of 2D 4⁴ grid-like layers based on dinuclear copper units. Complex 3 features a rare 3D (6,8)-connected topological net consisting of trimetallic clusters. 12-connected pentanuclear cadmium clusters are observed in complex 4 and the resulting structure shows an uncommon (4,12)-connected topology. The structural differences among 1-4 demonstrate that the nature of the N-donor assistant ligands and metal ions can play critical roles in the formation and structures of the resulting complexes. Magnetic studies showed antiferromagnetic interactions for 1 and 3. In addition, the luminescent property of 4 was also studied.     

Three complexes based on ligands 1-hydroxybenzotriazole and 1,4-benzenedicarboxylic acid: Synthesis, structures and luminescence properties

Three new complexes, [Mn(OBt)₂(H₂O)₄]·3H₂O (1) (OBt = 1-hydroxybenzotriazole ion), [Zn₂(OBt)₂(BDC)(H₂O)·H₂O]_n (2) (H₂BDC = 1,4-benzenedicarboxylic acid), and [Cu₃(OBt)₂(BDC)(μ₃-OH)₂(H₂O)₂·2H₂O]_n (3) were synthesized by hydrothermal method and were characterized by elemental analysis, IR spectroscopy, TGA, XRPD, and single-crystal X-ray diffraction. The results from single-crystal X-ray diffraction indicate that 1, 2 and 3 are zero-dimensional (0D), two-dimensional (2D) and two-dimensional (2D) frameworks, respectively. In particular, there are all two crystallographically unique metal ions in the structures of complexes 2 and 3. Complex 2 possesses two helical chains in its structure. In the structure of 3, the chains that are built from tri-copper clusters and μ₃-O atoms are connected with BDC²⁻ to construct 2D grid structure. The luminescence properties of the three complexes were investigated.     

Two new 3D (3,8)-connected metal-organic frameworks based on zinc-triazole secondary building units and benzenetricarboxylate linkers

Two new zinc-triazole-carboxylate frameworks constructed from secondary building units (SBUs), [Zn₅(trz)₄(btc)₂(DMF)₂(H₂O)₂]·2H₂O·DMF (1) and [Zn₄(trz)₃(btc)₂(CH₃CN)(H₂O)]·5H₂O·(Bu₄N) (2), [Htrz = 1,2,4-triazole, H₃btc = 1,2,4-benzenetricarboxylate, Bu₄N = tetrabutylammonium], have been synthesized by solvothermal reactions and characterized by single-crystal X-ray diffraction analyses, X-ray power diffraction, elemental analyses, infrared spectra and thermogravimetric analyses. Both compounds 1 and 2 exhibit 3D (3,8)-connected tfz-d nets with {4³}₂{4⁶.6¹⁸.8⁴} topology symbol built from rod-shaped {[Zn₅(trz)₄]⁶⁺}_n SBUs (1) and {[Zn₄(trz)₃]⁵⁺}_n SBUs (2). In two compounds, rodlike units are connected by btc ligands via different modes. Additionally, solid state fluorescent emission spectra of two compounds show fluorescent properties at room temperature.     

Effects of steric/basic properties of Lewis bases on the degree of aggregation of zinc(II) pivalate complexes

A triangular [Zn₃(μ₃-OH)(OC(O)^tBu)(μ₂-κ¹O:κ¹O′-O₂C^tBu)₄(3,5-lutidine)₃] (1), a paddlewheel based dinuclear [Zn(μ₂-κ¹O:κ¹O′-O₂C^tBu)₂L]₂ [L = 2,4-lutidine (2), 3,4-lutidine (3), and 2,3-lutidine (4)] and an hourglass based linear trinuclear [Zn₃(μ₂-κ¹O:κ¹O′-O₂C^tBu)₆(pyridine)₂] (5) complexes were synthesized to understand the role of subtle steric/basic properties of Lewis bases on the degree of aggregation of the products. The mononuclear Zn(OC(O)^tBu)₂·2H₂O was also prepared in order to probe the origin of the μ₃-OH moiety in complex 1. Complexes 1-5 and Zn(OC(O)^tBu)₂·2H₂O were characterized by microanalytical, IR, TGA/DTA, solution (¹H and ¹³C) NMR, solid-state cross-polarization magic angle spinning (CP-MAS) ¹³C NMR, mass spectral data and single crystal X-ray diffraction data. Complex 1 represents the first example of a discrete trinuclear zinc(II) carboxylate complex that contains a [Zn₃(μ₃-OH)]⁵⁺ core with zinc atoms in three distinct geometries namely a distorted tetrahedral, trigonal bipyramidal, and octahedral. A plausible mechanism for the formation of complexes 1-5 was explained with the aid of point zero charge (pzc) model.     

Lewis acidity of platinum(II)-based Baeyer-Villiger catalysts: An electrochemical approach

The electrochemical behavior of the Pt(II)-based Baeyer-Villiger catalysts of the general formulae [Pt(μ-OH)(P^∩P)]₂(BF₄)₂ (P^∩P = dppe (1a), 2Fdppe (1 b), 4Fdppe (1c), dfppe (1d), dmpe (1e), depe (1f), dippe (1g), dtbpe (1h)) and [Pt(OH₂)₂(P^∩P)](OTf)₂ (P^∩P = dppe (2a), 2Fdppe (2b), 4Fdppe (2c), dfppe (2d)) is reported. They exhibit irreversible reduction processes whose potentials reflect the Lewis acidity of the metal centres, showing (for the aromatic diphosphine complexes) overall relations with the number of fluorine atoms, with J_Pt-P, with the ν(CN) coordination shift of a ligand isocyanide probe and with the catalytic activity. Single-crystal X-ray diffraction analyses were carried out for [Pt(μ-OH)(4Fdppe)]₂(BF₄)₂ (1c) and [Pt(μ-OH) (dippe)]₂(BF₄)₂ (1g).     

Synthesis and characterization of two new triazolate-aliphatic dicarboxylate bridged Zn(II) coordination polymers based on 2D layer motifs with different crystal packing

Two new zinc(II)-triazole-aliphatic dicarboxylate coordination polymers, [Zn(trz)(Hsuc)]_n (1), [Zn₂(trz)₂(tar)]_n (2), have been hydrothermally synthesized by reaction of Zn salt, Htrz with H₂suc and H₂tar, respectively (Htrz = 1,2,4-triazole, H₂suc = succinic acid, H₂tar = tartaric acid).Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by X-ray powder diffraction, elemental analyses, IR spectra and TG analyses. Compound 1 displays a 2D layer structure containing {[Zn₄(trz)₄]⁴⁺}_n layers decorated by the suc ligand. Compound 2 is in a 3D structure formed by the interconnection of 2D {[Zn₄(trz)₄]⁴⁺}_n layers with tar ligand, resulting a 3,4-connected topological network. Due to the different coordination mode and conformation of aliphatic carboxylate ligand, the similar 2D {[Zn₄(trz)₄]⁴⁺}_n layers stack in the -AAA- fashion in 1, while the {[Zn₄(trz)₄]⁴⁺}_n layers hold together in the -ABAB- stacking sequence in 2. Additionally, the two compounds show strong fluorescence in the solid state at room temperature.     

Metal-organic open frameworks with one-dimension channels assembled with pyridine 2,6-dicarboxylic acid and N-containing auxiliary ligands: Syntheses, crystal structures, and physical characterization

Four new complexes, {[Mn(imH)₂(pdc)]·H₂O}_n (1), [Zn₂(pdc)₂(H₂O)₅]·2H₂O (2), [Zn(imH)₂(pdc)]·H₂O (3), {[Zn₂(pdc)₂(bpy)(H₂O)₂]·5H₂O}_n (4) [imH = imidazole pdc = pyridine 2,6-dicarboxylate, bpy = 4,4′-bipyridine] have been synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR, PXRD, single-crystal X-ray diffraction and thermogravimetric analyses. All the four complexes display a three-dimensional (3D) open framework with one-dimensional (1D) channels that are filled with lattice water molecules. Particularly, in 4, the lattice water molecules form an infinite water chain. Both 1 and 4 consist of 1D polymeric chains. While 2 contains a dinuclear Zn(II) unit, and 3 is a mononuclear complex. Further, the result of thermal analysis of 1 and 2 shows the robustness of the overall supramolecular three-dimensional architecture. Complexes 1, 3, and 4 exhibit strong fluorescent emissions in the solid state at room temperature and could be significant in the field of photoactive materials.     

Structure and properties of cobalt ortho-phenylenediacetate coordination polymers with rigid dipyridyl ligands

Divalent cobalt coordination polymers containing both ortho-phenylenediacetate (ophda) and rigid dipyridyl ligands 4,4′-bipyridine (bpy) or 1,2-bis(4-pyridyl)ethylene (dpee) display different topologies depending on carboxylate binding mode, tether length, and inclusion of charged species. [Co(ophda)(H₂O)(dpee)]_n (1) displays a common (4,4) grid layer motif. Use of the shorter bpy tether afforded {[Co₂(ophda)₂(bpy)₃(H₂O)₂][Co(bpy)₂(H₂O)₄](NO₃)₂·2bpy·7H₂O}_n (2) or [Co(ophda)(bpy)]_n (3) depending on cobalt precursor. Compound 2 manifests 5-connected [Co₂(ophda)₂(bpy)₃(H₂O)₂]_n pillared bilayer slabs with rare 4⁸6² SnS topology and entrained [Co(bpy)₂(H₂O)₄]²⁺ complex cations. The 3-D coordination polymer 3 has an uncommon 4,6-connected binodal (4⁴6²)(4⁴6¹⁰8) fsc topology, and shows ferromagnetic coupling (J = +1.5(2) cm⁻¹) along 1-D spiro-fused [Co(OCO)₂]_n chain submotifs.     

Construction of several d metal coordination polymers based on aromatic polycarboxylate and flexible triazole-based ligand

To investigate the effect of organic anions on the coordination frameworks, we synthesized five new complexes, namely, {[Zn₃(μ-OH₂)₂(btc)₂(btx)₃]·4H₂O}_n (1), [Zn(bdc)(btx)]_n (2), {[Ag₈(3,5-pydc)₄(btx)₄]·8H₂O}_n (3), [Ag(2,6-Hpydc)(btx)]_n (4) and [Cd₂(μ₂-OH₂)(2,6-pydc)₂(btx)]_n (5) (H₂bdc = 1,4-benzenedicarboxylic acid; H₃btc = 1,3,5-benzenetricarboxylate; 3,5-H₂pydc = pyridine-3,5-dicarboxylic acid; 2,6-H₂pydc = pyridine-2,6-dicarboxylic acid), which were obtained by the reactions of 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) as main ligand, and several aromatic polycarboxylate as organic anions with different d¹⁰ metal salts. Single crystal structure analysis shows that complexes 1, 3 and 5 possess 3D structures, 2 takes a 2D layer motif, and 4 displays a 1D chain structure. The distinct structures indicate that polycarboxylate anions with the diverse coordination modes and coordination groups can affect the topologies of metal-organic frameworks. In addition, the luminescence measurements reveal that the complexes 1, 2 and 5 exhibit strong fluorescent emissions in the solid state at room temperature.     

Second-ligand-dependent multi-fold interpenetrated architectures of two 3-D metal(II)-organic coordination polymers

By one-pot solvothermal reaction, two 3-D metal(II)-organic coordination polymers [Zn₂(SDC)₂(L¹)] (1) and [Zn(SDC)(L²) · 2DMF] (2) are self-assembled from trans-4,4′-stilbenedicarboxylic acid (H₂SDC), 4-(4-((E)-2-(pyridin-4-yl)vinyl)- styryl)pyridine (L¹), 4,4′-bipyridine(L²) and zinc salts in the presence of N,N′-dimethylbenzenamine, and characterized by single-crystal X-ray diffraction analyses. The overall structure of 1 with total potential solvent-accessible volume of 44.2% presents a fourfold interpenetrated topology from 6-connected CdO-like nets, while that of 2 with nanosized channels occupied by free DMF molecules displays a fivefold interpenetrated framework of [Zn(SDC)(L²)]_n from 4-connected diamondoid networks. The topology types and the multi-fold interpenetrating of 1 and 2 are dependent on the second ligands (L¹ and L²). Solid-state 1 and 2 have expected photoluminescence with maximum emission at 484 and 505 nm, respectively.     

Synthesis, characterization and antibacterial activity of Fe, Co, Cu and Zn complexes probed by transmission electron microscopy

We synthesized iron(III), cobalt(II), copper(II) and zinc(II) complexes [Fe^III(HBPClNOL)Cl₂]·H₂O (1), [Co^II(H₂BPClNOL)Cl₂] (2), [Cu^II(H₂BPClNOL)Cl]Cl·H₂O (3), and [Zn^II(HBPClNOL)Cl] (4), where H₂BPClNOL is the ligand (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)]propylamine). The complexes obtained were characterized by elemental analysis, IR and UV-visible spectroscopies, electrospray ionization mass spectrometry (ESI-MS), tandem mass spectrometry (MS/MS), and cyclic voltammetry. X-ray diffraction studies were performed for complexes (3) and (4) revealing the presence of mononuclear and dinuclear structures in solid state for (3). However, the zinc complex is mononuclear in solid state. Biological studies of complexes (1)-(4) were carried out in vitro for antimicrobial activity against nine Gram-positive bacteria (Staphylococcus aureus strains RN 6390B, COL, ATCC 25923, Smith Diffuse, Wood 46, enterotoxigenic S. aureus FRI-100 (SEA+), FRI S-6 (SEB+) and SEC FRI-361) and animal strain S. aureus LSA 88 (SEC/SED/TSST-1+). The following sequence of inhibition promoted by the complexes was observed: (4) > (2) > (3) > (1), showing the effect of the metal on the biological activity. To directly observe the morphological changes of the internal structure of bacterial cells after the treatment, transmission electron microscopy (TEM) was employed. For the most active complex [Zn^II(HBPClNOL)Cl] (4), granulation deposits around the genetic material and internal material leaking were clearly detected.     

Hydrothermal synthesis of two novel three-dimensional cobalt(II) metal-organic frameworks based on polycarboxylate and benzotriazole

The hydrothermal reactions of 1,4-H₂BDC or 1,4-H₂CDC, HBTA, with Co(NO₃)₂ · 6H₂O in basified solvent gave rise to two coordination polymers, Co₅(μ₃-OH)₂(1,4-BDC)₃(BTA)₂ (1), [Co(1,4-CDC)_0.5(BTA)] (2) (1,4-H₂BDC = 1,4-benzenedicarboxylic acid, 1,4-H₂CDC = 1,4-cyclohexanedicarboxylic acid, HBTA = benzotriazole) and characterized by elemental analysis, IR, single-crystal X-ray diffraction and variable-temperature magnetic measurements. Complex 1 crystallizes in the triclinic system, P space group; the structure determination reveals that 1 has a scarcely reported 8-connected 3D self-penetrating structure based on pentanuclear cobalt clusters. Complex 2 is monoclinic system, P2₁/c space group, and the X-ray structural analysis shows that 2 has a 3D infinite network with (4.6⁴.8)(4².6².8²) topology. Complex 1 exhibits moderately antiferromagnetic coupling, while complex 2 indicating strong spin-orbit coupling.     

Diverse coordination of polynuclear copper(II) complexes constructed from benzene tetracarboxylates

The reaction of aqueous solutions of the preformed 1:1 Cu(ClO₄)₂-polydentate amine with tetrasodium 1,2,4,5-benzene tetracarboxylate (Na₄bta) afforded three different types of polynuclear compounds. These include the tetranuclear complexes: [Cu₄(Medpt)₄(μ₄-bta)(ClO₄)₂(H₂O)₂](ClO₄)₂·2H₂O (1), [Cu₄(pmdien)₄(μ₄-bta)(H₂O)₄](ClO₄)₄ (2), [Cu₄(Mepea)₄(μ₄-bta)(H₂O)₂](ClO₄)₄(3), [Cu₄(TPA)₄(μ₄-bta)](ClO₄)₄·10H₂O (4) and [Cu₄(tepa)₄(μ₄-bta)](ClO₄)₄·2H₂O (5), the di-nuclear: [Cu₂(DPA)₂(μ₂-bta)(H₂O)₂]·4H₂O (6), [Cu₂(dppa)₂(μ₂-bta)(H₂O)₂]·4H₂O (7) and [Cu₂(pmea)₂(μ₂-bta)]·14H₂O (8) and the trinuclear complex [Cu₃(dppa)₃(μ₃-bta)(H₂O)_2.25](ClO₄)₂·6.5H₂O (9) where Medpt = 3,3′-diamino-N-methyldipropylamine, pmedien = N,N,N′,N″,N″-pentamethyldiethylenetriamine, Mepea = [2-(2-pyridyl)ethyl]-(2-pyridylmethyl)methylamine, TPA = tris(2-pyridylmethyl)amine, tepa = tris[2-(2-pyridyl)ethyl)]amine, DPA = di(2-pyridymethyl)amine, dppa = N-propanamide-bis(2-pyridylmethyl)amine and pmea = bis(2-pyridylmethyl)-[2-(2-pyridylethyl)]amine. The complexes were structurally characterized by elemental analyses, spectroscopic techniques, and by X-ray crystallography for complexes 1, 2, 4, 6, 7 and 9. X-ray structure of the complexes reveal that bta⁴⁻ is acting as a bridging ligand via its four deprotonated caboxylate groups in 1, 2 and 4, three carboxylate groups in 9 and via two trans-carboxylates in 6 and 7. The complexes exhibit extended supramolecular networks with different dimensionality: 1-D in 2 and 4 due to hydrogen bonds of the type O-H···O, 2-D in 1 and 7, and 3-D network in 6 as a result of hydrogen bonds of the types N-H···O and O-H···O. Magnetic susceptibility measurements showed very weak antiferromagnetic coupling between the Cu^II ions in 1-5, 7-9 (|J| = 0.02-0.87 cm⁻¹) and weak ferromagnetic coupling for 6 (J = 0.08 cm⁻¹).     

Organo-Group 15 derivatives of triosmium clusters containing naphthyl ligands

Reactions of the clusters Os₃(μ-H)₂(μ₃-1-OC₁₀H₆)(CO)₉, 1, and Os₃(μ-H)(μ-2-OC₁₀H₇)(CO)₁₀, 2, with the group 15 ligands EPh₃ (E=P, As, Sb) generally afforded the mono- and, or disubstituted derivatives. These derivatives tend to decompose during chromatographic separations on silica gel; thus one of the decomposition products from the reaction of 1 with PPh₃ has been identified as Os(H)₂(CO)₂(PPh₃)₂, 3. The molecular structures of 3, as well as the derivatives Os₃(μ-H)₂(μ₃-1-OC₁₀H₆)(CO)₈(AsPh₃), 4, Os₃(μ-H)₂(μ₃-1-OC₁₀H₆)(CO)₇(SbPh₃)₂, 5c, Os₃(μ-H)(μ-2-OC₁₀H₇)(CO)₈(AsPh₃)₂, 7b, and Os₃(μ-H)(μ-2-OC₁₀H₇)(CO)₈(SbPh₃)₂, 7c, have been determined by single crystal X-ray diffraction studies.     

Hydrothermal syntheses, crystal structures and topological analyses of four new 3D coordination polymers with mixed ligands

Four new coordination polymers, namely [Ni_1.5(L)(fum)_0.5(mal)(H₂O)]·4H₂O (1), [Zn₂(L)(male)₂]·3H₂O (2), [Ni(L)(adi)_0.5(H₂O)]·0.5(adi)·2.5H₂O (3), and [Zn₂(L)(adi)₂]·5H₂O (4) (L, tetrakis(imidazol-1-ylmethyl)methane; fum, fumarate; mal, malate; male, maleate; adi, adipate) have been synthesized under hydrothermal condition and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. In compound 1, the L, fum, and mal connect the Ni(II) atoms to form a three-dimensional framework. Topologically, the compound shows a trinodal (3,4)-connected (4·10²)(4²·8²·10²)(4²·8⁴) net. Interestingly, the fum and mal came from the configuration transformation and addition reaction of maleate during the synthesis, respectively. In compound 2, the L ligands link the Zn(II) centers to generate a 2D layer, which are further connected by the male ligands to furnish a 3D chrial 4-connected (3·7⁵) net. In compound 3, the adi ligands and the L ligands link the Ni(II) centers to form a 3D framework. Topologically, compound 3 displays a (4,5)-connected net with the Schläfli symbol of (4²·5²·6²)(4²·5³·6⁴·7). In compound 4, the L and adi ligands link the binuclear Zn(II) clusters to yield an intricate 3D (3,6)-connected net with the Schläfli symbol of (4·6²)(4³·6¹²). The fluorescence and thermal stability of complexes 1-4 have also been investigated.     

In situ hydrothermal syntheses, crystal structures and luminescent properties of two novel zinc(II) coordination polymers based on tetrapyridyl ligand

Two novel Zn(II) coordination polymers, [Zn(2-pytpy)(fum)]_n·nH₂O (1) and [Zn₆(4-pytpy)₃(mal)₄]_n·5n(H₂O) (2), (2-pytpy = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine, 4-pytpy = 4′-(4-pyridyl)-4,2′:6′,4″-terpyridine, H₂fum = fumaric acid and H₂mal = malic acid) have been hydrothermally synthesized and structurally characterized. Notably, in situ ligand reactions occur in the formation of complexes 1 and 2, in which maleic acid is converted into fumaric acid and malic acid, respectively. Complex 1 is a 1D infinite chain structure, which is extended into a supramolecular layer by intermolecular π…π stacking interactions. Complex 2 is a 3D network structure, in which the bidentate-bridging 4-pytpy ligands link the layers based on the tetranuclear Zn(II) subunits to form the (4,10)-connected network. The luminescent properties of 1 and 2 have been investigated with emission spectra and UV-Vis diffuse reflectance spectra in the solid state. Additionally, these two complexes possess great thermal stabilities.     

Two novel three-dimensional coordination polymers based on metal clusters: Hydrothermal syntheses, crystal structures and luminescence

Two novel coordination polymers with interesting supramolecular architecture, [Zn₂(OH)(BTC)(bix)] (1) and [Cd₂(CDC)₂(bix)₂] (2) (H₃BTC = 1,3,5-benzenetricarboxylic acid, H₂CDC = trans-1,4-cyclohexanedicarboxylic acid and bix = 1,2-bis(imidazol-1-ylmethyl)benzene) have been obtained via hydrothermal reaction and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Complex 1 features a 3D network with one of the scarce (3,8)-connected (4³)₂(4⁶.6¹⁸.8⁴) topology based on the rare CdI₂-type layer constructed from secondary building units (SBUs) of zinc clusters. While 2 exhibits a scarcely reported eight-connected 3⁶.4¹⁶.5⁶ net with dinuclear cadmium clusters as secondary building units. The luminescent properties of 1 and 2 along with the bix ligand in the solid state were investigated.