Two- and three-dimensional photoluminescent Cd(II)-carboxylate coordination frameworks bridged by benzenepentacarboxylate and N-donor ligands

Reactions of Cd(OAc)₂·H₂O, benzenepentacarboxylic acid (H₅bpc), 2,2′-bpy/4,4′-bpy, and Et₃N yield two new coordination polymers [Cd₅(bpc)₂(2,2′-bpy)₄(H₂O)₄] (1) and [Cd₅(bpc)₂(4,4′-bpy)₂(H₂O)₄]·3H₂O (2). Complex 1 is a 2-D structure based on six-connected Cd-carboxylate layers. Adjacent layers are linked by π–π interactions and hydrogen bonds to generate a layered supramolecular network. Complex 2 is a 3-D coordination framework. The bpc ligands adopting μ ₇-bridging mode connect Cd(II) ions to form a 3-D open framework with elliptic channels, in which the coordinated 4,4′-bpy ligands fill to support the whole framework. Complex 2 exhibits strong photoluminescence at room temperature.     

Silver(I) 3-D-supramolecular coordination frameworks constructed by the combination of coordination bonds and supramolecular interactions

Room temperature reactions of the ternary adducts of AgNO₃, bipodal ligand [4,4′-bipyridine (4,4′-bpy) or trans-1,2-bis(4-pyridyl)ethylene (tbpe) or 1,2-bis(4-pyridyl)ethane (bpe)] and organic ligand [4-aminobenzoic acid (4-aba) or 4-hydroxybenzoic acid (4-hba) or terephthalate ion (tph)] afford new 3-D supramolecular coordination polymers (SCPs), namely, {[Ag(4,4′-bpy) · H₂O](4-ab) · 2H₂O} (1), {[Ag(tbpe)]0.5(4-hb) · 3H₂O} (2), [Ag₂(L)₂ · (tph)] (L = 4,4′-bpy, tbpe) (3,4) and {[Ag₂(bpe)₂ · (tph)] · 2H₂O} (5). The bipodal ligand coordinates to silver forming a 1-D cationic chain (A), while the organic ligand and solvent form a 1-D anionic chain (B) via hydrogen bonds. The chains construct layers which are connected via hydrogen bonds and π–π stacking forming a 3-D network structure. The presence of the carboxylate, amino and hydroxyl groups in the organic ligands significantly extend the dimensionality via hydrogen bonds. All the SCPs 1–5 exhibit strong luminescence.     

Syntheses,crystal structures,and luminescence of two new coordination polymers based on biphenyl-2,2′,4,4′-tetracarboxylate

Two new coordination polymers, [Zn(H₂btc)(4,4′-bpy)₂] _n (1) and {[Cd(H₂btc) (terpy)]?·?H₂O} _n (2) (H₄btc?=?biphenyl-2,2′,4,4′-tetracarboxylic acid, 4,4′-bpy?=?4,4′-bipyridine, terpy?=?terpyridine), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. Complexes 1 and 2 are 1-D chains linked through partially deprotonated H₄btc. The adjacent 1-D chains of 1 are further formed into 2-D supramolecular architecture through inter-chain N–H···O hydrogen bonds. In contrast, due to a different auxiliary ligand, the 1-D chains of 2 are further extended into 3-D supramolecular framework through inter-chain O–H···O hydrogen bonds. Thermal stabilities and luminescence of 1 and 2 were also studied.     

Synthesis and crystal structures of nickel(II) supramolecules containing hexaazamacrocycles and aromatic carboxylate ligands

Two new nickel(II) complexes, {[Ni(L)(4,4′-bpdc)] · 3H₂O} _n (1) and {[Ni(L)(2,6-ndc)] · 2CH₃CN} _n (2) (L = 1,8-dihydroxylethyl-1,3,6,8,10,13-hexaazacyclotetradecane, 4,4′-bpdc = 4,4′-biphenyldicarboxylate, 2,6-ndc = 2,6-naphthalenedicarboxylate), have been synthesized and structurally characterized by spectroscopic and X-ray diffraction methods. Compound 1 shows a 3-D supramolecule which is composed of two different series of 1-D coordination polymers, where each 1-D chain runs in different directions and interacts by π–π stacking at the intersection. Compound 2 contains 1-D coordination polymers in which 1-D chains run in the same direction. The 1-D chains are interconnected by hydrogen bonds in an undulated fashion to form a 3-D supramolecule.     

Four Co(II)/Zn(II) coordination polymers with a multidentate ligand: syntheses,structures, thermal,and photoluminescent properties

Two pairs of isostructural transition metal coordination polymers, {[Co(L)(H₂O)]_n} (1) and {[Zn(L)(H₂O)]_n} (3), {[Co(L)(4,4′-bipy)(H₂O)]·H₂O}_n (2) and {[Zn(L)(4,4′-bipy)(H₂O)]·H₂O}_n (4) (H₂L = N-pyrazinesulfonyl-glycine acid and 4,4′-bipy = 4,4′-bipyridine), have been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental and thermogravimetric analyses. The structures show that 1 and 3 display 2-D polymeric grid frameworks with a 3-connected (4, 8²) topology. 2 and 4 also exhibit a 2-D polymeric grid structure, but are constructed by a 4-connected (4, 4) topology. The adjacent 2-D polymeric grid frameworks for 1–4 are further linked by hydrogen bonding O–H?O interactions to form 3-D supramolecular interweaved orderly networks. The fluorescent properties of 3 and 4 were investigated in the solid state.     

Synthesis,structures, and characterization of cadmium(II), cobalt(II), and copper(II) metal polymers with tetrazole-1-acetate

Three new coordination polymers {[Cd(tza)(2,2′-bpy)(H₂O)](ClO₄)} _n 1, {[Co(tza)(2,2′-bpy)(H₂O)](ClO₄)} _n 2, and {[Cu(tza)(phen)](ClO₄)} _n 3 (Htza = tetrazole-1-acetic acid, 2,2′-bpy = 2,2′-bipyridyl, phen = 1,10-phenanthroline) were synthesized and characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectra. Complexes 1 and 2 exhibit 3-D architectures formed by π–π interaction of 2,2′-bpy ligands interlinking to the adjacent 2-D layers. Complex 3 is a 1-D zigzag double chain and the 3-D structure is formed by π–π stacking interaction of phen and nonclassical hydrogen bonding.     

Crystal structures and magnetic properties of three cobalt(II)–organic frameworks with nanoscale channels

Three cobalt(II) coordination polymers, {[Co(nip)(4,4′-bpy)] · 3H₂O} _n (1), [Co(nip)(bpe)] _n (2), and [Co(nip)(bpp)(H₂O)] _n (3), were hydrothermally synthesized by the reaction of cobalt nitrate hexahydrate and nip with 4,4′-bpy, bpe, and bpp [nip = 5-nitro-1,3-benzenedicarboxylato, 4,4′-bpy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane], respectively. Co(II) displays different coordination in the three complexes, resulting in different structures with nanoscale channels. Compounds 1 and 2 form 2-D layer structures, but 3 has a two-fold interpenetrated 3-D framework. The magnetic properties associated with their crystal structures were investigated.     

Two new coordination host frameworks for the inclusion of 4-amino-benzophenone guest molecules

The synthesis and structural characterization of novel organometallic coordination polymers are reported. The reaction of Cd(NO₃)₂ and 4,4′-bipy in CH₃OH/H₂O gave a 2D coordination network formulated as {[Cd(4,4′-bpy)₂·(H₂O)₂](NO₃)₂·4H₂O}¹⁰, which was used to capture an organic guest species (4-amino-benezopheone, C₁₃H₁₁NO (3)) to obtain {[Cd(4,4′-bpy)₂(NO₃)(H₂O)]·NO₃·(C₁₃H₁₁NO)₂} (1). Using L (L=4,4′-trimethylenedipyridine) instead of 4,4′-bipy, {[Cd(L)₂(H₂O)₂]·2H₂O·2NO₃·C₁₃H₁₁NO} (2) was synthesized, which has an interesting configuration.     

Synthesis,Structures, and Photoluminescence Properties of Five Novel Zinc(II) and Cadmium(II) Coordination Polymers based on Different Zwitterionic Pyridine Ligands

A series of five new Zn^II and Cd^II mixed‐ligand coordination polymers, namely, {[Zn(L₁)(4,4′‐bpy)] · (ClO₄) · 2H₂O} ( 1 ), {[Zn(L₂)(4,4′‐bpy)_0.5] · (ClO₄)} ( 2 ), {[Zn(L₃)(4,4′‐bpy)] · (NO₃) · 2H₂O} ( 3 ), {[Cd(L₄)(4,4′‐bpy)_0.5(NO₃)] · 5H₂O} ( 4 ), and {[Zn(L₄)(4,4′‐bpy)] · Cl · H₂O} ( 5 ) [4,4′‐bpy = 4,4′‐bipyridine, L₁ = 4‐carboxy‐1‐(4‐carboxybenzyl)pyridin‐1‐ium chloride, L₂ = 3‐carboxy‐1‐(4‐carboxybenzyl)pyridin‐1‐ium chloride, L₃ = 4‐carboxy‐1‐(3‐carboxybenzyl)pyridin‐1‐ium chloride, and L₄ = 3‐carboxy‐1‐(3‐carboxybenzyl)pyridin‐1‐ium chloride], were obtained by the reactions of the 4,4′‐bipyridine with four dicarboxylate zwitterionic pyridine ligands. Single‐crystal X‐ray structural analyses reveal that the five complexes demonstrate different molecular frameworks coming from various coordination modes and flexibilities of different dicarboxylate zwitterionic pyridine ligands and central metal atoms. Mononuclear twofold dinuclear 2D twofold interpenetrating net for 2 , four‐coordinate mononuclear twofold interpenetrating 2D layer for 3 , mononuclear 2D layer arranged in parallel and with large grids for 4 , and twofold trans interpenetrating 2D network for compound 5 . The structural diversities in 1 – 5 indicate that the nature of the ligands and the presence of different metal atoms have a great influence on central metal coordination modes and the structural topologies of the metal‐organic molecular architectures. In addition, π ··· π stacking interactions also play important roles in the final crystal packing and supramolecular frameworks. The powder X‐ray diffraction, elemental analysis, and photoluminescence properties of 1 – 5 were studied, which show that architectures play an important role in emission bands and intensities.     

Syntheses,structures, and properties of two 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and polycarboxylate ligands

Two 2-D Cd(II) complexes, {[Cd(imb)(bdc)(H₂O)]·CH₃OH}_n (1) and {[Cd(imb)(Hbtc)(CH₃OH)]·2H₂O·CH₃OH}_n (2), have been synthesized by reactions of CdCl₂·2.5H₂O with 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,3-benzenedicarboxylic acid (H₂bdc) or 1,3,5-benzenetricarboxylic acid (H₃btc). Single-crystal X-ray diffraction shows that 1 possesses an infinite 2-D layered structure in which all the carboxylates chelate Cd(II) and imb bridge Cd(II) ions. Complex 2 also features an infinite 2-D layered structure and imb ligands also bridge Cd(II) ions, but two carboxylates of each 1,3,5-benzenetricarboxylate coordinate to Cd(II) in monodentate or chelating mode, leaving the third one, which is not deprotonated, uncoordinated. IR spectra, fluorescent properties, and thermogravimetric analyses of both complexes have been investigated.     

Zinc(II) complexes of 4,4-oxybis(benzoate) and 2-propyl-4,5-imidazoledicarboxylic acid with bipyridine

The reactions of dicarboxylic acids, such as 4,4-oxybis(benzoic acid) [H₂oba] and 2-propyl-4,5-imidazoledicarboxylate [H₃pimdc], under hydrothermal conditions in the presence of an appropriate zinc salt yield two mononuclear complexes, which are characterized by elemental analysis, infrared spectrum, electrochemical analysis, thermal analysis, and X-ray crystal diffraction. Complex 1, [Zn(Hoba)₂(4,4′-bpy)₂], forms a 2-D supramolecular layer like rhombus via hydrogen bonds (O–H?···?N). Complex 2, [Zn(H₂pimdc)₂(2,2′-bpy)]?·?H₂O, forms a zig-zag chain via multiple hydrogen bonds and C–H?···?π interactions. The moderate hydrogen-bond interactions in 1 and 2 play an important role for structural stability. The electrochemical analyses of 1 and 2 reveal electron transfer of 1 is reversible and 2 is quasi-reversible.     

Ancillary ligand-controlled assembly of three coordination polymers: synthesis,characterization, luminescent,and catalytic properties

Abstract

By changing the ancillary ligands, three new zinc-based coordination polymers (CPs), {[Zn(4,4′-bpy)(H₂O)₄]·(TDC)·(H₂O)}_n (1), [Zn(2,2′-dmbpy)(TDC)]_n (2), and [Zn₂(3,3′-dmbpy)(TDC)₂]_n (3) (H₂TDC =2,5-thiophenedicarboxylic acid, 4,4′-bpy =4,4′-bipyridine, 2,2′-dmbpy =2,2′-dimethyl-4,4′-bipyridine, 3,3′-dmbpy =3,3′-dimethyl-4,4′-bipyridine) have been synthesized under the same reaction conditions (H₂O, pH =7–8, and 140°C) and were structurally characterized. 1 is a linear chain structure and further connected into a 3-D structure through hydrogen bonds. 2 shows a 2-D (4,4) network when the dinuclear [Zn₂(COO)₄N₂] building unit is regarded as a six-connected node. 3 has a twofold-interpenetrating 3-D zinc-organic framework pcu topology. Furthermore, 1–3 show strong photoluminescence at room temperature in the solid state, and the catalytic activities of 1–3 for degradation of methyl orange in a Fenton-like process have been investigated. The results suggest that the ancillary ligands influence the final resulting CPs.     

Ligand concentration-dependent supramolecular complexes with uncoordinated carbonyl groups based on a new pyrazole carboxylic acid ligand

One new pyrazole-based ligand, 1-carboxymethyl-3,5-dimethyl-1H-pyrazole-4-carboxylic acid (H₂cmdpca), has been synthesized and characterized. Structural analysis reveals that H₂cmdpca crystallizes in the monoclinic system and adopts a 3-D supramolecular network via the interaction of intermolecular hydrogen bonds. The reactions of Cd(II) ions with H₂cmdpca and 4,4′-bipyridine (4,4′-bpy) afforded three metal complexes, [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)₃]·H₂O (1), [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)]·3H₂O (2), and [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)] (3). Structural analyses reveal that these complexes are all monoclinic and 1, 2, and 3 exhibit mononuclear, 1-D chain, and 1-D with binuclear loop structures, respectively, which are further assembled into 3-D supramolecular frameworks through non-covalent interactions. 1 and 2 are true supramolecular isomers, while 2 and 3 are “pseudo-supramolecular” isomers. In addition, the thermal stability and luminescent properties of the complexes are also investigated.     

Syntheses,crystal structures,and catalytic activities of three new Cu(II) coordination polymers based on 2-(1H-1,2,4-triazole)-1-acetic acid

Three new coordination polymers, {[Cu(trza)(2,2′-bipy)(H₂O)]?·?(ClO₄)} _n (1), {[Cu(trza)(2,2′-bipy)(H₂O)]?·?(BF₄)} _n (2), and {[Cu(trza)(4,4′-bipy)]?·?(H₂O)?·?(ClO₄)} _n (3) (Htrza?=?2-(1H-1,2,4-triazole)-1-acetic acid), have been synthesized and characterized by single-crystal X-ray diffraction analysis. Both 1 and 2 exhibit 1-D chain structure while 3 displays 2-D layer structure. The catalytic activities of 1 and 3 in the green oxidative coupling of 2,6-dimethylphenol have been investigated.     

Thermal characterization of new complexes of Zn(II) and Cd(II) with some bipyridine isomers and propionates

New mixed ligand complexes of the following stoichiometric formulae: M(2-bpy)₂(RCOO)₂·nH₂O, M(4-bpy)(RCOO)₂·H₂O and M(2,4’-bpy)₂(RCOO)₂·H₂O (where M(II)=Zn, Cd; 2-bpy=2,2’-bipyridine, 4-bpy=4,4′-bipyridine, 2,4′-bpy=2,4′-bipyridine; R=C₂H₅; n=2 or 4) were prepared in pure solid-state. These complexes were characterized by chemical and elemental analysis, IR and conductivity studies. Thermal behaviour of compounds was studied by means of DTA, DTG, TG techniques under static conditions in air. The final products of pyrolysis of Cd(II) and Zn(II) compounds were metal oxides MO. A coupled TG/MS system was used to analyse of principal volatile products of thermal decomposition or fragmentation of Zn(4-bpy)(RCOO)2·H2O under dynamic air and argon atmosphere. The principal species correspond to: C⁺, CH⁺, CH₃ ⁺, C₂H₂ ⁺, HCN⁺, C₂H₅ ⁺ or CHO⁺, CH₂O⁺ or NO⁺, CO₂ ⁺, ¹³C¹⁶O₂ ⁺ and ¹²C¹⁶O¹⁸O⁺ and others; additionally CO⁺ in argon atmosphere.     

Nanoparticles of a new zinc(II) coordination polymer: synthesis,characterization, thermal,and structural studies

Nanoparticles of a Zn(II) coordination polymer {[Zn(DADMBTZ)(CH₃COO)₂] _n , DADMBTZ?=?2,2′-diamino-5,5′-dimethyl-4,4′-bithiazole} were synthesized by reaction of Zn(NO₃)₂?·?4H₂O, CH₃COONH₄ and DADMBTZ by a sonochemical method. The nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. [Zn(DADMBTZ)(CH₃COO)₂] _n was structurally characterized by single-crystal X-ray diffraction. In this four-coordinate compound with nearly C₂ symmetry, DADMBTZ is bidentate. The metal lies in a pseudo-tetrahedral environment and is ligated by the two bithiazole ring nitrogen atoms and an oxygen from each of the two monodentate acetates; 2-D networks are formed via N–H···O hydrogen bonds. Thermal stability of [Zn(DADMBTZ)(CH₃COO)₂] _n was studied by thermal gravimetric and differential thermal analyses. A ZnO nanostructure was obtained by direct thermolyses at 500°C under air. The ZnO nanostructure was characterized by SEM, XRD, and FT-IR spectroscopy.     

Supramolecular networks constructed by cationic copper(II) complexes incorporating hybrid water–anionic polymeric assemblies

Two complexes, [Cu₂(TFSA)(2,2′-bpy)₄]?·?TFSA?·?8H₂O (1) and {[Cu(4,4′-bpy)(H₂O)₂]?·?TFSA?·?6H₂O} _n (2) (H₂TFSA?=?tetrafluorosuccinic acid, 2,2′-bpy?=?2,2′-bipyridine, and 4,4′-bpy?=?4,4′-bipyridine), have been synthesized and structurally characterized by X-ray structural analyses. Complex 1 is a binuclear molecule bridged by TFSA ligands; 2 is a 1-D chain bridged by 4,4′-bpy ligands. The asymmetric units of the two complexes are composed of cationic complexes [Cu₂(TFSA)(2,2′-bpy)₄]²⁺ (1) and [Cu(4,4′-bpy)(H₂O)₂]²⁺ (2), free TFSA anion, and independent crystallization water molecules. A unique 2-D hybrid water–TFSA anionic layer by linkage of {[(H₂O)₈(TFSA)]^2?} _n fragments consisting of 1-D T6(0)A2 water tape and TFSA anionic units by hydrogen bonds in 1 was observed. Unique 2-D hybrid water–TFSA anionic layer generated by the linkage of {[(H₂O)₆(TFSA)]^2?} _n fragments consisting of cyclic water tetramers with appended water molecules and TFSA anionic units, and 1-D metal–water tape [Cu–H₂O?···?(H₂O)₆?···?H₂O^?] _n in 2 were found. 3-D supramolecular networks of the two complexes consist of cationic complexes and water–TFSA anionic assemblies connected by hydrogen bonds.     

Syntheses,crystal structures and antibacterial activities of M(II) benzene-1,2,3-triyltris(oxy)triacetic acid complexes

Four metal(II) complexes with benzene-1,2,3-triyltris(oxy)triacetic acid (H₃L), {[Co_1.5(L)(H₂O)₆]·6H₂O}_n (1), {[Co_1.5(L)(4,4′-bipy)_1.5(H₂O)₄]·4H₂O}_n (2), {[Co(HL)(2,2′-bipy)(H₂O)₂]·1.5H₂O}_n (3), and {[Cu(HL)(phen)(H₂O)₂]·H₂O}_n (4) (4,4′-bipy = 4,4′-bipyridine; 2,2′-bipy = 2,2′-bipyridine; phen = phenanthroline), were prepared and structurally characterized. Complex 2 displays a 1-D structure, while 1, 3, and 4 reveal 0-D structures, which further extend to 3-D supramolecular networks by hydrogen bonding interactions, of which 1 and 4 contain double-helical chains, 2 includes meso-helices, and 3 comprises single-helices. Furthermore, the thermal stabilities and antibacterial activities of the complexes were studied.     

Two transition metal supramolecular compounds based on 2-(4-isopropylbenzoyl)benzoic acid: syntheses,crystal structures,and luminescent properties

Two new supramolecular compounds, [Zn₂(L)₃(4,4′-bpy)(OH)]_n (1) and [Cd(L)₂(2,2′-bpy)(H₂O)]·2H₂O (2) (HL?=?2-(4-isopropylbenzoyl)benzoic acid, 4,4′-bpy?=?4,4′-bipyridine, 2,2′-bpy?=?2,2′-bipyridine), have been hydrothermally synthesized and characterized by elemental analysis, infra-red spectroscopy, thermal gravimetric analyzes, and single-crystal X-ray diffraction. 1 exhibits 1-D chain and 2 is 0-D mononuclear. They are both linked into 2-D supramolecular layers by non-covalent interactions. Luminescence properties were also investigated.     

Two Zn(II) coordination polymers constructed by a new tricarboxylate and different N-containing ligands: synthesis,crystal structures,and selective luminescence sensing for Fe3+ in aqueous solution

Two Zn(II) coordination polymers, {[Zn₃(L)₂(bipy)₂(H₂O)₄}_n (1) and {[Zn(HL)(4,4′-bibp)}_n (2), were obtained from Zn(II) nitrate, a tricarboxylate ligand (H₃L) and different N-containing ligands with hydrothermal conditions, where H₃L = 4-((6-carboxynaphthalen-2-yl)oxy)phthalic acid, bipy = 4,4′-bipyridine, and 4,4′-bibp = 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl. Single-crystal X-ray analysis reveals that 1 has a 2-D layer framework formed by L^3? and bipy and 2 has an infinite 1-D structure with Zn₂ units built by 4,4′-bibp ligands. The phase purity, IR spectra, thermal stabilities, and fluorescence properties in the solid state of 1 and 2 were investigated. Moreover, 1 and 2 were chosen as fluorescent probes to sense different metal ions, showing selective response to Fe³⁺ ion through luminescence quenching. The possible sensing mechanism to Fe³⁺ ion is also discussed.