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.     

Construction of Mononuclear Copper(II) and Trinuclear Cobalt(II) Complexes Based on Asymmetric Salamo‐Type Ligands

Mononuclear copper(II) and trinuclear cobalt(II) complexes, namely [Cu(L¹)]₂ · CH₂Cl₂ and [{Co(L²)(EtOH)}₂Co(H₂O)] · EtOH {H₂L¹ = 4,6‐dichloro‐6′‐methyoxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol and H₃L² = 6‐ethyoxy‐6′‐hydroxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol}, were synthesized and characterized by elemental analyses, IR and UV/Vis spectroscopy, and single‐crystal X‐ray diffraction. In the Cu^II complex, the Cu^II atom is four‐coordinate, with a N₂O₂ coordination sphere, and has a slightly distorted square‐planar arrangement. Interestingly, the obtained trinuclear Co^II complex is different from the common reported 2:3 (L:Co^II) salamo‐type Co^II complexes. Infinite 2D layer supramolecular structures are formed via abundant intermolecular hydrogen bonding and π ··· π stacking interactions in the Cu^II and Co^II complexes.     

Synthesis and Crystal Structures of Manganese(II) and ­Cobalt(II) Complexes with 2, 6‐Dimethoxybenzoic Acid and Additional N‐Donor Ligands

Three coordination compounds [Mn₃(dmb)₆(H₂O)₄(4, 4′‐bpy)₃(EtOH)]_n ( 1 ) and [M(dmb)₂(pyz)₂ (H₂O)₂] [M^II = Co ( 2 ), Mn ( 3 )] (Hdmb = 2, 6‐dimethoxybenzoic acid, 4, 4′‐bpy = 4, 4′‐bipyridine, pyz = pyrazine) were synthesized and characterized by single‐crystal X‐ray diffraction analysis. Compound 1 consists of infinite 1D polymeric chains, in which the metal entities are bridged by 4, 4′‐bpy ligands. There are four crystallographically independent Mn^II atoms in the linear chain with different coordination modes, which is only scarcely reported for linear polymers. The isostructural crystals of 2 and 3 are composed of neutral mononuclear complexes. In crystal the complexes are combined into chains by intermolecular O–H ··· N hydrogen bonds and π–π interactions between antiparallel pyrazine molecules.     

Supramolecular Architectures with Open Frameworks Constructed by Transitional Metal Ions,Linear Dicarboxylic Acid,and 2,2′‐Bipyridine

Four new transitional metal supramolecular architectures, [Zn(cca)(2,2′‐bpy)]_n · n(2,2′‐bpy) ( 1 ), [Cu(cca)(2,2′‐bpy)]_n ( 2 ), [Zn(bpdc)(2,2′‐bpy)(H₂O)]_n · 0.5nDMF · 1.5nH₂O ( 3 ), and [Co(bpdc)(2,2′‐bpy)(H₂O)]_n · nH₂O ( 4 ) (H₂cca = p‐carboxycinnamic acid; H₂bpdc = 4,4′‐biphenyldicarboxylic acid; 2,2′‐bpy = 2,2′‐bipyridine) were synthesized by hydrothermal reactions and characterized by single crystal X‐ray diffraction, elemental analyses, and IR spectroscopy. Although the metal ions in these four compounds are bridged by linear dicarboxylic acid into 1D infinite chains, there are different π–π stacking interactions between the chains, which results in the formation of different 3D supramolecular networks. Compound 1 is of a 3D open‐framework with free 2,2′‐bpy molecules in the channels, whereas compound 2 is of a complicated 3D supramolecular network. Compounds 3 and 4 are isostructural. Both compounds have open‐frameworks.     

A Luminescent Silver(I) Metal‐Organic Framework with New (4,6)‐Connected Topology Based on Mixed Tetrachlorotereph­thalate and 2,2′‐Bipyridine Ligands

A silver(I) coordination polymer with mixed 2,3,5,6‐tetrachloro‐1,4‐benzenedicarboxylate (BDC‐Cl₄) and 2,2′‐bipyridine (2,2′‐bpy) ligands, [Ag₂(BDC‐Cl₄)(2,2′‐bpy)]_n ( 1 ), was synthesized and structurally characterized. Compound 1 features a robust three‐dimensional (3D) network, exhibiting a new (4,6)‐connected net with the Schläfli symbol of (3² · 4² · 5 · 6)₂(3² · 4² · 5² · 8⁷ · 9 · 10). The photoluminescence properties of 1 were investigated in the solid state at room temperature.     

Syntheses and Structures of Coordination Polymers Constructed by Semi‐Rigid Bicarboxylic Acid Ligands

The complexes [Co(L¹)(mpy)] ( 1 ), [Ni(L¹)(mpy)] ( 2 ), [Co(L¹)(tbpy)] · 2H₂O ( 3 ), [Ni₂(L¹)₂(tbpy)₂] · 5H₂O ( 4 ), [Mn₂(L¹)₂(tbpy)₂] · 3H₂O ( 5 ), [Mn(L¹)(biim‐3)] ( 6 ), [Ni₂(L¹)₂(btb)₂(H₂O)] · 2H₂O ( 7 ), [Cu(L²)(mpy)] · 7H₂O ( 8 ), [Co(L²)(tbpy)(H₂O)] ( 9 ), [Ni(L²)(tbpy)(H₂O)] · H₂O ( 10 ), [Cu(L²)(bib)] · 2H₂O ( 11 ), and [Cu(L²)(btb)] · 2H₂O ( 12 ) [H₂L¹ = (3‐carboxyl‐phenyl)‐(4‐(2′‐carboxyl‐phenyl)‐benzyl)ether, H₂L² = 3‐carboxy‐1‐(4′‐carboxybenzyl)‐2‐oxidopyridinium, mpy = 2‐(4‐(4′‐methylphenyl)‐6‐(pyrindin‐2‐yl)pyridin‐2‐yl)pyridine), tbpy = 2‐(4‐(4′‐tert‐butylphenyl)‐6‐(pyrindin‐2‐yl)pyridin‐2‐yl)pyridine), biim‐3 = 1,3‐bis(imidazol‐1′‐yl)propane, btb = 1,4‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene, bib = 1,4‐bis(imidazol‐1′‐ylmethyl)benzene] were synthesized. Compounds 1 – 6 have similar 1D chain structures, which are further linked by π–π interactions to generate supramolecular double chains for 1 and 2 , and supramolecular layers for 3 – 6 . Compound 7 displays a 3D 6‐connected framework with (4⁴ · 6¹¹) topology. Compound 8 features a monomolecular structure, which is further linked by hydrogen bonds between the lattice water molecules and carboxylate oxygen atoms of L² anions to form a 2D supramolecular layer. The monomolecular structures of 9 and 10 are connected by hydrogen bonds and π–π interactions simultaneously to generate supramolecular layers. Compounds 11 and 12 show layer structures.     

Supramolecular Stuctures from Mononuclear,Binuclear and 2D Net of Copper(II) Complexes with 6‐Hydroxypicolinic Acid

First examples of transition metal complexes with HpicOH [Cu(picOH)₂(H₂O)₂] ( 1 ), [Cu(picO)(2,2′‐bpy)]·2H₂O ( 2 ), [Cu(picO)(4,4′‐bpy)_0.5(H₂O)]_n ( 3 ), and [Cu(picO)(bpe)_0.5(H₂O)]_n ( 4 ) (HpicOH = 6‐hydroxy‐picolinic acid; 2,2′‐bpy = 2,2′‐bipyridine; 4,4′‐bpy = 4,4′‐bipyridine; bpe = 1,2‐bis(4‐pyridyl)ethane) have been synthesized and characterized by single‐crystal X‐ray diffraction. The results show that HpicOH ligand can be in the enol or ketonic form, and adopts different coordination modes under different pH value of the reaction mixture. In complex 1 , HpicOH ligand is in the enol form and adopts a bidentate mode. While in complexes 2 – 4 , as the pH rises, HpicOH ligand becomes in the ketonic form and adopts a tridentate mode. The coordination modes in complexes 1 – 4 have not been reported before. Because of the introduction of the terminal ligands 2,2′‐bpy, complex 2 is of binuclear species; whereas in complexes 3 and 4 , picO ligands together with bridging ligands 4,4′‐bpy and bpe connect Cu^II ions to form 2D nets with (12³)₂(12)₃ topology.     

Cadmium(II) Complexes with Mixed cis‐Epoxysuccinate and 2,2′‐Bipyridyl‐Like Ligands: Syntheses,Crystal Structures,and Luminescent Properties

Two new Cd^II complexes, [Cd( ces )(phen)]_∞ ( 1 ) and {[Cd( ces )(bpy)(H₂O)](H₂O)}₂ ( 2 ), were prepared by slow solvent evaporation methods from mixtures of cis‐epoxysuccinic acid and Cd(ClO₄)₂ · 6H₂O in the presence of phen or bpy co‐ligand ( ces = cis‐epoxysuccinate, phen = 1,10‐phenanthroline, and bpy = 2,2′‐bipyridine). Single‐crystal X‐ray diffraction analyses show that complex 1 has a one‐dimensional (1D) helical chain that is further assembled into a two‐dimensional (2D) sheet, and then an overall three‐dimensional (3D) network by the interchain C–H ··· O hydrogen bonds. Complex 2 features a dinuclear structure, which is further interlinked into a 3D supramolecular network by the co‐effects of intermolecular C–H ··· O and C–H ··· π hydrogen bonds as well as π ··· π stacking interactions. The structural differences between 1 and 2 are attributable to the intervention of different 2,2′‐bipyridyl‐like co‐ligands. Moreover, 1 and 2 exhibit intense solid‐state luminescence at room temperature, which mainly originates from the intraligand π→π* transitions of aromatic co‐ligands.     

A novel copper(II) coordination polymer with 2,2′‐bipyridyl‐3,3′‐di­carboxylic acid

A novel copper(II) coordination polymer, poly­[[[aqua­copper(II)]‐μ₃‐2,2′‐bipyridyl‐3,3′‐di­carboxyl­ato‐κ⁴N,N′:O:O′] dihydrate], {[Cu(C₁₂H₆N₂O₄)(H₂O)]·2H₂O}_n, was obtained by the reaction of CuCl₂·2H₂O and 2,2′‐bipyridyl‐3,3′‐di­carboxylic acid (H₂L) in water. In the mol­ecule, each Cu^II atom is five‐coordinated and lies at the centre of a square‐pyramidal basal plane, bridged by three L ligands to form a two‐dimensional (4,4)‐network. Each L moiety acts as a bridging tetradentate ligand, coordinating to three Cu^II atoms through its two aromatic N atoms and two O atoms of the two carboxyl groups. The two‐dimensional square‐grid sheets superimpose in an off‐set fashion through the inorganic water layer.     

A novel cadmium(II) coordination polymer with biphenyl‐3,3′,4,4′‐tetra­carboxylic acid and 4,4′‐bipyridine

A novel cadmium(II) coordination polymer, poly[[[bis­(4,4′‐bipyridine)cadmium(II)]‐μ₃‐4,4′‐dicarboxy­biphenyl‐3,3′‐di­carboxyl­ato] 0.35‐hydrate], {[Cd(C₁₆H₈O₈)(C₁₀H₈N₂)₂]·0.35H₂O}_n, was obtained by reaction of Cd(CH₃COO)₂·3H₂O, 4,4′‐bipyridine (4,4′‐bpy) and biphenyl‐3,3′,4,4′‐tetra­car­boxylic acid (H₄L) under hydro­thermal conditions. Each Cd^II atom lies at the centre of a distorted octa­hedron, coordinated by four O atoms from three H₂L²⁻ ligands and N atoms from two monodentate 4,4′‐bpy ligands. Each H₂L²⁻ ligand coordinates to three Cd^II atoms through two carboxyl­ate groups, one acting as a bridging bidentate ligand and the other in a chelating bidentate fashion. Two Cd atoms, two H₂L²⁻ anions and four 4,4′‐bpy ligands form a ring dimer node, which links into an extended broad zonal one‐dimensional chain along the c axis.     

Synthesis,Structures, and Catalytic Properties of Two ­Cobalt(II) Coordination Polymers Based on 5‐Substituted Isophthalate and Flexible Bis(benzimidazole) Co‐ligands

Two new Co^II coordination polymers, [Co(L₁)_0.5(hip)]_n ( 1 ) and [Co(L₂)(mip) · 2H₂O]_n ( 2 ) [L₁ = 1,1′‐(1,4‐butanediyl)bis‐1H‐benzimidazole, L₂ = 1,3‐bis(5,6‐dimethylbenzimidazol‐1‐yl)‐2‐propanol, H₂hip = 5‐hydroxyisophthalic acid, H₂mip = 5‐methylisophthalic acid], were synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, and X‐ray single‐crystal diffraction. Complex 1 exhibits a 3D supramolecular network constructed with 2D (4,4) layer by O–H ··· O hydrogen bonding. Complex 2 has 1D ladder‐like chains, which are further assembled into a 3D supramolecular framework by π–π stacking interactions. In addition, fluorescence and catalytic properties of compounds 1 and 2 were investigated in solid state.     

基于2,4′-二羧基二苯甲酮构筑的具有一维梯状链和一维隧道的三维超分子体系

采用水热法设计合成了两个新型三维超分子化合物H₂L·H₂O (1)和[Ag(bpy)₂]·HL·H₂O (2) (其中bpy=2,2'-联吡啶, H₂L=2,4′-二羧基二苯甲酮),晶体结构分析表明,它们均是通过氢键采用不同的连接方式拓展而成。其中,化合物1 是2,4′-二羧基二苯甲酮和水分子通过O–H···O氢键形成的一维梯状链扩展构筑的三维超分子体系;化合物2 则是2,4′-二羧基二苯甲酮和水分子通过两种氢键形成含有一维隧道的三维超分子体系。有趣的是,[Ag(bpy)₂]⁺ 阳离子通过π–π 堆积和弱的Ag···Ag相互作用连在一起,进而以客体形式填充其中。荧光性质研究表明,由于存在bpy的螯合与堆积效应,化合物2相比配体和化合物1,其荧光发射峰发生红移。     

One‐dimensional copper(II) coordination polymers based on 1,3‐bis(pyridin‐4‐yl)propane and diimine ligands

Two one‐dimensional (1D) coordination polymers (CPs), namely catena‐poly[[[aqua(2,2′‐bipyridine‐κ²N,N′)(nitrato‐κO)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′] nitrate], {[Cu(NO₃)(C₁₀H₈N₂)(C₁₃H₁₄N₂)(H₂O)]·NO₃}_n ( 1 ), and catena‐poly[[[aqua(nitrato‐κO)(1,10‐phenanthroline‐κ²N,N′)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′] nitrate], {[Cu(NO₃)(C₁₂H₈N₂)(C₁₃H₁₄N₂)(H₂O)]·NO₃}_n ( 2 ), have been synthesized using [Cu(NO₃)(NN)(H₂O)₂]NO₃, where NN = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen), as a linker in a 1:1 molar ratio. The CPs were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray structure determination. The 1,3‐bis(pyridin‐4‐yl)propane (dpp) ligand acts as a bridging ligand, leading to the formation of a 1D polymer. The octahedral coordination sphere around copper consists of two N atoms from bpy for 1 or phen for 2 , two N atoms from dpp, one O atom from water and one O atom from a coordinated nitrate anion. Each structure contains two crystallographically independent chains in the asymmetric unit and the chains are linked via hydrogen bonds into a three‐dimensional network.     

Triaqua(2,2′‐bipyridine‐κ2N,N′)(nitrato‐κO)manganese(II) nitrate

The crystal structure of the title compound, [Mn(NO₃)(C₁₀H₈N₂)(H₂O)₃]NO₃, contains a monomeric [Mn(NO₃)(bpy)(H₂O)₃]⁺ cation (bpy is 2,2′‐bi­pyridine) and a nitrate anion. The Mn^II ion is coordinated by one chelating bpy [Mn—N 2.241 (3) and 2.259 (3) Å], three water mol­ecules [Mn—O 2.120 (3)–2.188 (3) Å] and a nitrate ligand [Mn—O 2.228 (2) Å] in a distorted octahedral geometry. There are O?H—O hydrogen‐bonding interactions between the ligated water mol­ecules and the ligated and unligated nitrate anions, resulting in double columns of stacked cations and anions.     

Two Zinc(II) Coordination Polymers Based on Terphenyl‐2,2′,4,4′‐tetracarboxylate and Dipyridyl Ligands: Syntheses,Crystal Structures,and Luminescent Properties

Two coordination polymers, {[Zn₂(L)(bpy)] · 2H₂O}_n ( 1 ) and [Zn₂(L)(bpe)]_n ( 2 ) [H₄L = terphenyl‐2,2′,4,4′‐tetracarboxylic acid, bpy = 4,4′‐bipyridine, and bpe = 1,2‐bis(4‐pyridyl)ethane], were hydrothermally synthesized under similar conditions and characterized by elemental analysis, IR spectroscopy, TGA, and single‐crystal X‐ray diffraction analysis. Compound 1 has a 3D framework containing Zn–O–C–O–Zn 1D chains. Compound 2 exhibits a 3D framework, which features tubular channels. The channels are occupied by bpe molecules. The differences in the structures demonstrate that the auxiliary dipyridyl‐containing ligand has a significant effect on the construction of the final framework. Additionally, the fluorescent properties of the two compounds were also studied in the solid state at room temperature.     

Impact of Reaction Conditions on the Structures of Nickel(II) Complexes Based on 3‐(4‐Carboxyphenyl)propionic Acid

Two new nickel(II) complexes, [Ni(4, 4′‐bpy)(H₂O)₄]_n · n(cpp) · 0.5nH₂O ( 1 ) and [Ni(cpp)(4, 4′‐bpy)(H₂O)₂]_n ( 2 ) [4, 4′‐bpy = 4, 4′‐bipyridine, H₂cpp = 3‐(4‐carboxyphenyl)propionic acid] were synthesized and characterized by single‐crystal X‐ray diffraction, elemental analysis, IR spectroscopy, and thermal analysis. In complex 1 , Ni^II ions are bridged by 4, 4′‐bpy into 1D chains, and cpp ligands are not involved in the coordination, whereas in complex 2 , cpp ligands adopt a bis(monodentate) mode and link Ni^II ions into 2D (4, 4) grids with the help of 4, 4′‐bpy ligands. Triple interpenetration occurs, which results in the formation of a complicated 3D network. The difference in the structures of the two complexes can be attributed to the different reaction temperatures and bases.     

A Structural Study of the Iminodiacetate Moiety Conformation in N‐(1‐adamantyl)‐iminodiacetate(2‐) Copper(II) Complexes

N,N‐bis(carboxymethyl)‐1‐adamantylamine acid (H₂BCAA) or N‐(1‐adamantyl)‐iminodiacetic acid forms zwitterions that are intra‐stabilized by a ‘bifurcated’ N⁺‐H···O(carboxyl)₂ interaction. In the crystal, both half‐protonated carboxyl groups of H₂BCAA^± are involved in linear O‐H···O inter‐molecular bridges of 2.46Å. In the studied BCAA‐Cu^II derivatives, the iminodiacetate‐moiety of the BCAA chelating ligand exhibits a mer‐NO₂ conformation in [Cu(BCAA)(H₂O)₂] ( 1 ) and [Cu(BCAA)(Him)]₂ ( 2 ), but a fac‐O₂+N(apical) conformation in [Cu(BCAA)(bpy)(H₂O)]·3.5H₂O ( 3 ) [Him = imidazole, bpy =2,2′‐bipyridine]. In clear contrast, dipyridylamine (dpya), as auxiliary ligand, seems to be unable to promote the fac‐O₂+N(apical) conformation in BCAA, as reveal the structures of two new salts with the trinuclear cation [(dpya)₂Cu‐μ₂‐Cu(BCAA)₂‐Cu(dpya)₂]²⁺ and the anions [Cu(BCAA)₂]^2? ( 4 ) or NO₃^? ( 5 ), respectively.     

Aqua(2,2′‐bi‐1H‐imidazole)chloro­copper(II) chloro­(imino­diacetato)copper(II) monohydrate

In the title compound, [CuCl(C₆H₆N₄)(H₂O)][Cu(C₄H₅NO₄)Cl]·H₂O, the Cu^II atom in the cation is coordinated by one Cl⁻ ion, two N atoms of the 2,2′‐biimidazole ligand and one aqua ligand. Within the anion, the Cu^II atom is bonded to one Cl⁻ ion, and one N and two O atoms of the imino­diacetate ligand. Neighbouring cations and anions are connected to each other by Cu·Cl semi‐coordination bonds of 2.830 (12) and 3.071 (12) Å, forming a Cu₂Cl₂ rectangular unit. The dinuclear units further link into a polymeric chain along the a axis through Cu·O_aqua interactions of 2.725 (3) Å. Including the long coordination bonds, the geometries around the Cu atoms in the cation and anion are square‐pyramidal and distorted octahedral, respectively.     

Synthesis,Structures, and Properties of Cadmium(II) and Nickel(II) Coordination Polymers Based on a 4,4′‐Biphenyl‐Containing Ligand and Aliphatic Carboxylic Acids

The coordination polymers [Cd₂(bbmb)₂(L₁)(HL₁)_0.5(H₂O)]_n ( 1 ), [Cd₂(bbmb)₂(L₂)₂(H₂O) · (H₂O)]_n ( 2 ), and [Ni(bbmb)₂(L₃)]_n ( 3 ), were synthesized by the hydrothermal reaction of 4,4′‐bis(benzimidazol‐1‐ylmethyl)biphenyl (bbmb) with Cd^II/Ni^II ions in the presence of three flexible aliphatic acids [tricarballylic acid (H₃L₁), succinate (H₂L₂), and adipate (H₂L₃)]. Complexes 1 – 3 were structurally characterized by elemental analysis, IR spectroscopy and single‐crystal and X‐ray powder diffraction analyses. Complex 1 presents a 3D 3‐nodal (3,4,4)‐connected net with 3 , 4 , 4T78 topology, 2 exhibits a 3D network with 6⁶‐ dia topology, whereas 3 is a chain structure and further extended by hydrogen bonding interactions to form a 2D supramolecular network. Structural diversity of these complexes indicates that these frameworks could be tuned by the conformation of bbmb ligand and the different coordination modes of the aliphatic carboxylate co‐ligands. The thermal and fluorescence properties, the catalytic activities of complexes 1 – 3 in a Fenton‐like process were investigated.     

Tetraaqua(4,4′‐dimethyl‐2,2′‐bipyridine‐κ2N,N′)nickel(II) sulfate monohydrate: a simple molecule with an extremely complex hydrogen‐bonding scheme

The title ionic compound, [Ni(C₁₂H₁₂N₂)(H₂O)₄]SO₄·H₂O, is composed of an Ni^II cation coordinated by a chelating 4,4′‐dimethyl‐2,2′‐bipyridine ligand via its two N atoms [mean Ni—N = 2.056 (2) Å] and by four aqua ligands [mean Ni—O = 2.073 (9) Å], the net charge being balanced by an external sulfate anion. The whole structure is stabilized by a solvent water molecule. Even though the individual constituents are rather featureless, they generate an extremely complex supramolecular structure consisting of a central hydrogen‐bonded two‐dimensional hydrophilic nucleus made up of complex cations, sulfate anions and coordinated and solvent water molecules, with pendant hydrophobic 4,4′‐dimethyl‐2,2′‐bipyridine ligands which interact laterally with their neighbours viaπ–π interactions. The structure is compared with closely related analogues in the literature.