Construction of three types of lanthanide complexes based on 3,4‐dimethylbenzoic acid and 5,5′‐dimethyl‐2,2′‐bipyridine: Syntheses,Structures, Thermodynamic properties,Luminescence, and Bacteriostatic activities

Three novel lanthanide complexes [Er (3,4‐DMBA)₃(5,5′‐DM‐2,2′‐bipy)(H₂O)] ( 1 ); [Tb₂ (3,4‐DMBA)₆(5,5′‐DM‐2,2′‐bipy)₂(H₂O)] ( 2 ); [Eu (3,4‐DMBA)₃(3,4‐DMHBA)(5,5′‐DM‐2,2′‐bipy)]₂ ( 3 ) (3,4‐DMHBA = 3,4‐dimethylbenzoic acid, 5,5′‐DM‐2,2′‐bipy =5,5′‐dimethyl‐2,2′‐bipyridine) were successfully synthesized via conventional solution method at room temperature and structurally characterized by single crystal diffraction. The structures of the complexes 1 – 3 were confirmed on the basis of elemental analysis, coordination titration analysis, IR and XRD. The molecular structures of complexes 2 and 3 are very particular: complex 2 has two same central metal ions but each metal ion has different coordination environment; in structure of the complex 3 , there are eight carboxylic acid ligands coordinated to the central metal ions, which have rarely been reported previously. The thermal decomposition mechanism of complexes 1 – 3 were investigated by the technology of simultaneous TG/DSC‐FTIR. The heat capacities of the complexes were recorded by means of DSC over the range of from 253.15 K to 345.15 K. The thermodynamic parameters, the smoothed values of heat capacities, enthalpy (H_T‐H_298.15K) and entropy (S_T‐S_298.15K) were also calculated. The bacteriostatic activities of the complexes were evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. What's more, the luminescence properties of complexes 2 and 3 were discussed, and their fluorescence lifetimes as well as the quantum yield of the Eu (III) were measured. To elucidate the energy transfer process of complexes 2 and 3, the energy levels of the relevant electronic states have been estimated.     

catena‐Poly­[bis­[(2,2‐bi­pyridine‐κ2N,N′)­copper(II)]‐μ4‐1,2,4,5‐benzene­tetra­carboxyl­ato‐κ4O1:O2:O3:O4]

In the title complex, [Cu₂(C₁₀H₂O₈)(C₁₀H₈N₂)₂]_n, the Cu^II cation has a four‐coordinated environment, completed by two carboxyl O atoms belonging to two 1,2,4,5‐benzene­tetra­carboxyl­ate anions (TCB⁴⁻) and two N atoms from one 2,2′‐bi­pyridine (2,2′‐bipy) ligand, forming a distorted square‐planar geometry. The [Cu(2,2′‐bipy)]²⁺ moieties are bridged by TCB⁴⁻ anions, which lie about inversion centres, forming an infinite one‐dimensional coordination polymer with a double‐chain structure along the a axis. A two‐dimensional network structure is formed via a face‐to‐face π–π interaction between the 2,2′‐bipy rings belonging to two adjacent double chains, at a distance of approximately 3.56 Å.     

Synthesis and Characterization of Two New Chiral Copper(II) Compounds Constructed from (+)‐N‐Tosyl‐L‐glutamic Acid

Chiral coordination polymers have attracted intense interest mainly due to their potential applications. Hence, two new chiral copper(II) coordination polymers {[Cu(tsgluO)(H₂O)]₂·3H₂O}_n ( 1 ) and [Cu(tsgluO)(2,2′‐bipy)]_n ( 2 ) (H₂tsglu?(+)‐N‐tosyl‐l‐glutamic acid; 2,2′‐bipy?2,2′‐bipyridine) were synthesized in the absence or presence of 2,2′‐bipy ligand and structurally characterized. A single crystal X‐ray diffraction study revealed that compound 1 consists of a paddle‐wheel dicopper(II) core, which links other equivalents via four tsgluO^2? ligands to form a 1D double chain. Such a chain is further interconnected through weak π‐π stacking and hydrogen bonding interactions to form a 3D H‐bonded supramolecular structure with 1D channels hosting lattice water molecules. Whereas, compound 2 , containing the coordinating 2,2′‐bipy, gives rise to a ladder‐like 1D double chain. Antiferromagnetic interactions were observed in 1 and 2 .     

“Roll‐over” Cyclometalation of 2,2′‐Bipyridine Platinum(II) Complexes in the Gas Phase: A Combined Experimental and Computational Study

In a combined experimental/computational investigation, the gas‐phase behavior of cationic [Pt(bipy)(CH₃)((CH₃)₂S)]⁺ ( 1 ) (bipy=2,2′‐bipyridine) has been explored. Losses of CH₄ and (CH₃)₂S from 1 result in the formation of a cyclometalated 2,2′‐bipyrid‐3‐yl species [Pt(bipy?H)]⁺ ( 2 ). As to the mechanisms of ligand evaporation, detailed labeling experiments complemented by DFT‐based computations reveal that the reaction follows the mechanistically intriguing “roll‐over” cyclometalation path in the course of which a hydrogen atom from the C(3)‐position is combined with the Pt‐bound methyl group to produce CH₄. Activation of a C? H‐bond of the (CH₃)₂S ligand occurs as well, but is less favored (35 % versus 65 %) as compared to the C(3)? H bond activation of bipy. In addition, the thermal ion/molecule reactions of [Pt(bipy?H)]⁺ with (CH₃)₂S have been examined, and for the major pathway, that is, the dehydrogenative coupling of the two methyl groups to form C₂H₄, a mechanism is suggested that is compatible with the experimental and computational findings. A hallmark of the gas‐phase chemistry of [Pt(bipy?H)]⁺ with the incoming (CH₃)₂S ligand is the exchange of one (and only one) hydrogen atom of the bipy fragment with the C? H bonds of dimethylsulfide in a reversible “roll‐over” cyclometalation reaction. The Pt^II‐mediated conversion of (CH₃)₂S to C₂H₄ may serve as a model to obtain mechanistic insight in the dehydrosulfurization of sulfur‐containing hydrocarbons.     

Synthesis of a Ruthenium(II) Compound based on 5‐(2‐Pyrimidyl)‐1H‐tetrazole for Photodynamic Therapy

Ru^II compounds have been universally investigated due to their unique physical and chemical properties. In this paper, a new Ru^II compound based on 2,2′‐bipy and Hpmtz [2,2′‐bipy = 2,2′‐bipyridine, Hpmtz = 5‐(2‐pyrimidyl)‐1H‐tetrazole], namely [Ru(2,2′‐bipy)₂(pmtz)][PF₆] · 0.5H₂O was prepared and characterized by elemental analysis, IR and single‐crystal X‐ray diffraction. [Ru(2,2′‐bipy)₂(pmtz)][PF₆] · 0.5H₂O shows a mononuclear structure and forms a three‐dimensional network by non‐classic hydrogen bonds. The ability of generation of ROS (reactive oxygen species) makes it has a low phototoxicity IC₅₀ (half‐maximal inhibitory concentration) after Xenon lamp irradiation on Hela cells in vitro. The results demonstrate that [Ru(2,2′‐bipy)₂(pmtz)][PF₆] · 0.5H₂O with high light toxicity and low dark toxicity may be a potential candidate for photodynamic therapy.     

一个新颖的由Zn配合物修饰的Keggin型钴钨酸盐：[Zn(2,2’-bipy)3]3{[Zn(2,2’-bipy)2(H2O)]2 [HCoW12O40] 2 }.H2O

通过水热合成技术,一个新颖的基于Zn配合物修饰的Keggin型钴钨酸的有机-无机杂化化合物：[Zn(2,2’-bipy)3]3{[Zn(2,2’-bipy)2(H2O)]2 [HCoW12O40] 2 }.H2O已经被合成,化合物通过红外光谱、热重分析和单晶X-射线衍射进行了表征。单晶X-射线衍射的结果显示标题化合物是由一个单支撑的{[Zn(2,2’-bipy)2(H2O)]2 [HCoW12O40] 2}6-多阴离子,三个[Zn(2,2’-bipy)3]2+阳离子和一个水分子构成。有趣的是[Zn(1)(2,2’-bipy)3]2+阳离子通过氢键连接在一起形成螺旋链。另外标题化合物在空气中是稳定的,并且在室温下显示了强的荧光。     

Four novel lanthanide complexes with 4‐ethylbenzoic acid and 5,5′‐dimethy‐2,2′‐bipyridine: Structures,luminescent, thermal properties and bacteriostatic activities

Four new lanthanide complexes [Ln(4‐EBA)₃(5,5′‐DM‐2,2′‐bipy)]₂·2C₂H₅OH (Ln = Ho ( 1 ), Tb ( 2 ), Er ( 3 )); [Ln(4‐EBA)₃(4‐EBAH)(5,5′‐DM‐2,2′‐bipy)]₂ (Ln = Eu( 4 ); 4‐EBA =4‐ethylbenzoate; 5,5′‐DM‐2,2′‐bipy =5,5′‐dimethy‐2,2′‐bipyridine; 4‐EBAH = 4‐ethylbenzoic acid) have been synthesized and characterized by elemental analysis and IR spectra. The single crystal results reveal that complexes 1 – 3 are isostructural. It is worth noting that the mole ratios of the carboxylate ligands and neutral ligands is 4:1 in complex 4 , which is different from the former and has been rarely reported. Nevertheless, all complexes are connected to form 1D chain by π ···π wake staking interactions. Additionally, the complexes 2 (Tb(III)) and 4 (Eu(III)) exhibit characteristic luminescent properties, indicating that ligands can be used as sensitizing chromophore in these systems. The thermal decomposition mechanism of the complexes has been investigated by TG/DSC–FTIR technology. Stacked plots of the FTIR spectra of the evolved gases show complexes broken down into H₂O, CO₂, and other gaseous molecules as well as the gaseous organic fragments. The studies on bacteriostatic activities of complexes show that four complexes have good bacteriostatic activities against Candida albicans but no bacteriostatic activity on Escherichia coli , and Staphylococcus aureus . Additionally, the complexes 1 to 3 have better bacteriostatic activities on Candida albicans than complex 4 .     

Two New Solvent‐modulated Zinc(II) Metal‐Organic Hybrid Materials based on Rigid Tripodal Carboxylate Ligand and 2,2′‐Bipy Co‐ligand: Crystal Structures and Luminescent Properties

The zinc(II) coordination polymers [Zn(Htatb)(2,2′‐bipy) · (NMP) · H₂O] ( 1 ) and [Zn₃(tatb)₂(2,2′‐bipy)₃ · H₂O] ( 2 ) (H₃tatb = 4,4′,4′′‐s‐triazine‐2,4,6‐triyl‐tribenzoic acid; 2,2′‐bipy = 2,2′‐bipyridyl, NMP = N‐methyl‐2‐pyrrolidon), were synthesized hydrothermally, and characterized by infrared spectroscopy (IR), powder X‐ray diffraction (PXRD), and single‐crystal X‐ray diffraction. Both compounds 1 and 2 possess expectant low dimensional coordination structures, which further connected into interesting 3D networks by hydrogen bond and strong π–π interactions. Moreover, the thermal stabilities and fluorescent properties of 1 and 2 were investigated.     

A cyanide‐bridged FeII–NdIII bimetallic assembly with a one‐dimensional ladder‐like chain structure

The title complex, catena‐poly[[[(2,2′‐bipyridine‐1κ²N,N′)tris(methanol‐2κO)(nitrato‐2κ²O,O′)‐μ‐cyanido‐1:2C:N‐cyanido‐1κC‐iron(II)neodymium(III)]‐di‐μ‐cyanido‐1:2′C:N;2:1′N:C] methanol solvate], {[Fe^IINd^III(CN)₄(NO₃)(C₁₀H₈N₂)(CH₃OH)₃]·CH₃OH}_n, is made up of ladder‐like one‐dimensional chains oriented along the c axis. Each ladder consists of two strands based on alternating Fe^II and Nd^III centers connected by cyanide bridges. Furthermore, two such parallel chains are connected by additional cyanide cross‐pieces (the `rungs' of the ladder), which likewise connect Fe^II and Nd^III centers, such that each [Fe(CN)₄(bipy)]²⁻ unit (bipy is 2,2′‐bipyridine) coordinates with three Nd^III centers and each Nd^III center connects with three different [Fe(CN)₄(bipy)]²⁻ units. In the complex, the iron(II) cation is six‐coordinated with a distorted octahedral geometry and the neodymium(III) cation is eight‐coordinated with a distorted dodecahedral environment.     

Bis[tris­(2,2′‐bipyridine)iron(II)] tetra­aqua­sodium(I) dodeca­tungsto­ferrate(III) dihydrate

The title compound, bis­[tris­(2,2′‐bipyridine)iron(II)] tetra­aqua­tetra‐μ₄‐oxo‐penta­cosa‐μ₂‐oxo‐undeca­oxo­iron(III)sodium(I)­dodeca­tungsten(VI) dihydrate, [Fe(C₁₀H₈N₂)₃]₂[NaFeW₁₂O₄₀(H₂O)₄]·2H₂O, consists of a dodeca­tungstoferrate(III) framework grafted on to an [Na(H₂O)₄]⁺ cation, two complex [Fe(2,2′‐bipy)₃]²⁺ cations (2,2′‐bipy is 2,2′‐bipyridine) and two uncoordinated water mol­ecules per formula unit.     

Solvothermal Synthesis and Crystal Structures of Two Manganese Complexes [Mn(II)(acac−)2(4,4′‐bipy)]n (bipy=4,4′‐bipyridine) and [Mn(III)(acac−)3]·4CO(NH2)2

Two special manganese complexes [Mn(II)(acac^?)₂(4,4′‐bipy)]_n (bipy=4,4′‐bipyridine) (complex 1 ) and [Mn(III)(acac^?)₃]·4CO(NH₂)₂ (acacH=acetylacetone) (complex 2 ) were synthesized in the same strategy by solvothermal method. Single crystal X‐ray diffraction revealed the complex 1 consists of one‐dimensional infinite coordination chain, with the manganese centers bridged by 4,4′‐bipy. And free carbamides of complex 2 connect with each other through the hydrogen bonds to form a 14‐membered carbamide ring and a zig‐zag plane. Both enantiomers of Mn(III)(acac^?)₃ exist in the structure, forming a racemate. Furthermore, these enantiomers and those zig‐zag planes are linked with hydrogen bonds to form an unique spatial network.     

A new three‐dimensional cobalt(II) coordination polymer based on V‐shaped 3,4′‐oxydibenzoate: synthesis,crystal structure and magnetic properties

A new coordination polymer (CP), namely poly[(μ‐4,4′‐bipyridine)(μ₃‐3,4′‐oxydibenzoato)cobalt(II)], [Co(C₁₄H₈O₅)(C₁₀H₈N₂)]_n or [Co(3,4′‐obb)(4,4′‐bipy)]_n ( 1 ), was prepared by the self‐assembly of Co(NO₃)₂·6H₂O with the rarely used 3,4′‐oxydibenzoic acid (3,4′‐obbH₂) ligand and 4,4′‐bipyridine (4,4′‐bipy) under solvothermal conditions, and has been structurally characterized by elemental analysis, IR spectroscopy, single‐crystal X‐ray crystallography and powder X‐ray diffraction (PXRD). Single‐crystal X‐ray diffraction reveals that each Co^II ion is six‐coordinated by four O atoms from three 3,4′‐obb^2? ligands, of which two function as monodentate ligands and the other as a bidentate ligand, and by two N atoms from bridging 4,4′‐bipy ligands, thereby forming a distorted octahedral CoN₂O₄ coordination geometry. Adjacent crystallographically equivalent Co^II ions are bridged by the O atoms of 3,4′‐obb^2? ligands, affording an eight‐membered Co₂O₄C₂ ring which is further extended into a two‐dimensional [Co(3,4′‐obb)]_n sheet along the ab plane via 3,4′‐obb^2? functioning as a bidentate bridging ligand. The planes are interlinked into a three‐dimensional [Co(3,4′‐obb)(4,4′‐bipy)]_n network by 4,4′‐bipy ligands acting as pillars along the c axis. Magnetic investigations on CP 1 disclose an antiferromagnetic coupling within the dimeric Co₂ unit and a metamagnetic behaviour at low temperature resulting from intermolecular π–π interactions between the parallel 4,4′‐bipy ligands.     

1:1 Adducts of 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid with dimethylammonium and 4,4′‐bipyridine

The title compounds, dimethylammonium 2‐{4‐[1‐(4‐carboxymethoxyphenyl)‐1‐methylethyl]phenoxy}acetate, C₂H₈N⁺·C₁₉H₁₉O₆⁻, (I), and 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid–4,4′‐bipyridine (1/1), C₁₉H₂₀O₆·C₁₀H₈N₂, (II), are 1:1 adducts of 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid (H₂L) with dimethylammonium or 4,4′‐bipyridine. The component ions in (I) are linked by N—H...O, O—H...O and C—H...O hydrogen bonds into continuous two‐dimensional layers parallel to the (001) plane. Adjacent layers are stacked via C—H...O hydrogen bonds into a three‐dimensional network with an –ABAB– alternation of the two‐dimensional layers. In (II), two H₂L molecules, one bipy molecule and two half bipy molecules are linked by O—H...N hydrogen bonds into one‐dimensional chains and rectanglar‐shaped rings. They are assembled viaπ–π stacking interactions and C—H...O hydrogen bonds into an intriguing zero‐dimensional plus one‐dimensional poly(pseudo)rotaxane motif.     

Three Dicyanidometallate(I)‐based Complexes Incorporating Hydrogen‐bonding, π–π Packing and d10–d10 Interactions with Auxiliary 2,2′‐Bipyridyl‐like Ligands

To investigate the influence of the non‐covalent interactions, such as hydrogen‐bonding, π–π packing and d¹⁰–d¹⁰ interactions in the supramolecular motifs, three cyanido‐bridged heterobimetallic discrete complexes {Mn(bipy)₂(H₂O)[Ag(CN)₂]}[Ag(CN)₂] ( 1 ), {Mn(phen)₂(H₂O)[Au(CN)₂]}₂[Au(CN)₂]₂ · 4H₂O ( 2 ), and {Cd(bipy)₂(H₂O)[Au(CN)₂]}[Au(CN)₂] ( 3 ) (bipy = 2,2′‐bipyridine, and phen = 1,10‐phenanthroline), which are based on dicyanidometallate(I) groups with 1:2 stoichiometry of metal ions and 2,2′‐bipyridyl‐like co‐ligands were synthesized and structurally characterized. In compound 1 , hydrogen bonding and π–π interactions governed the supramolecular contacts. In compound 2 , the incorporation of aurophilic, hydrogen bonding and π–π interactions result in a 3D supramolecular network. In compound 3 , hydrogen bonding and π–π stacking interactions result in a 2D supramolecular layer. In the three complexes, hydrogen‐bonding, π–π packing and/or d¹⁰–d¹⁰ interactions can play important roles in increasing the dimensionality of supramolecular assemblies.     

New Examples of Metal Coordination Architectures of 3,3′,4,4′‐Biphenyltetracarboxylic Acid – Syntheses,Crystal Structures,and Physical Properties

Four new metal‐organic frameworks [Cu₂(2,2′‐bipy)₂(ox)(H₂O)₂]·(H₂bptc) ( 1 ), [Cu(bptc)_0.5(phen)(H₂O)]·H₂O ( 2 ), Co₂(bptc)(bmb)_1.5 ( 3 ) and [Cd₂(bptc) (bmb)]·3H₂O ( 4 ) (H₄bptc = 3,3′,4,4′‐biphenyltetracarboxylic acid, ox = oxalate, phen = 1,10‐phenanthroline, 2,2′‐bipy = 2,2′‐bipyridine and bmb = 4,4′‐bis((1H‐imidazol‐1‐yl)methyl)biphenyl), were obtained by reactions of the corresponding metal salts with H₄bptc and N‐containing auxiliary ligands and their structures were determined by single‐crystal X‐ray diffraction. The results reveal that 1 has a 0‐D structure consisting of discrete ionic entities, while 2 features a 1‐D ladder structure. Additionally, there exist π‐π stacking and intermolecular hydrogen‐bonding interactions in 1 and 2 , respectively, forming 3‐D supramolecular structures. In 3 ‐ 4 , undulating 2‐D metal‐bptc layer structures are formed with two different coordination modes of bptc carboxylate groups, respectively, which are further extended by bmb into 3‐D structures. Magnetic properties of 1 and 3 have been studied. The photoluminescence property of 4 has also been investigated. Moreover, nonlinear optical measurements showed that 4 displayed a second‐harmonic‐generation (SHG) response of 0.7 times of that for urea.     

Synthesis and Characterization of Antimony(III) Complexes of Thioamides,and Crystal Structure of {[Sb(Imt)2Cl2]2((2‐Imt)}Cl2(Imt=Imidazolidine‐2‐thione)

Antimony(III) complexes of thioamides [thioamides=thiourea (Tu), N,N′‐dimethylthiourea (Dmtu), tetramethylthiourea (Tmtu), imidazolidine‐2‐thione (Imt) and diazinane‐2‐thione (Diaz)] with the general formulae, Sb(thione)_nCl₃ (n=1, 2, 2.5, 3) were prepared and characterized by elemental analysis, IR and NMR (¹H, ¹³C) spectroscopic methods. The spectral data of the complexes are consistent with the coordination of the thiones to antimony(III). The crystal structure of one of them, {[Sb(Imt)₂Cl₂]₂(μ₂‐Imt)}Cl₂ ( 1 ), was determined by X‐ray crystallography, which shows that the complex is dinuclear consisting of two [Sb(Imt)₂Cl₂] units bridged by an Imt molecule. In 1 , the antimony atom is bonded to two chlorine atoms, two sulfur atoms of coordinated Imt molecules and one sulfur atom of a bridging Imt molecule. The antimony environment can be considered to be distorted octahedral with one Cl^? ion weakly bound to antimony.     

Syntheses,crystal structures and blue emission of three zinc(II) coordination polymers with a 4,4′‐dicarboxybiphenyl sulfone ligand

Three novel zinc complexes [Zn(dbsf)(H₂O)₂] ( 1 ), [Zn(dbsf)(2,2′‐bpy)(H₂O)]·(i‐C₃H₇OH) ( 2 ) and [Zn(dbsf)(DMF)] ( 3 ) (H₂dbsf = 4,4′‐dicarboxybiphenyl sulfone, 2,2′‐bpy = 2,2′‐bipyridine, i‐C₃H₇OH = iso‐propanol, DMF = N,N‐dimethylformamide) were first obtained and characterized by single crystal X‐ray crystallography. Although the results show that all the complexes 1–3 have one‐dimensional chains formed via coordination bonds, unique three‐dimensional supramolecular structures are formed due to different coordination modes and configuration of the dbsf^2? ligand, hydrogen bonds and π–π interactions. Iso‐propanol molecules are in open channels of 2 while larger empty channels are formed in 3 . As compared with emission band of the free H₂dbsf ligand, emission peaks of the complexes 1–3 are red‐shifted, and they show blue emission, which originates from enlarging conjugation upon coordination. Copyright © 2006 John Wiley & Sons, Ltd.     

Spectroscopic,Thermal, and Structural Studies of Two New Co‐Crystals of [4,4′‐Bithiazole]‐2,2′‐diamine

Two new 2 : 1 co‐crystals based on [4,4′‐bithiazole]‐2,2′‐diamine (=2,2′‐diamino‐4,4′‐bithiazole (DABTZ)) with 2,2′‐bipyridine (bipy) and benzo‐18‐crown‐6 (bk) were synthesized by slow‐evaporation method in MeOH. These co‐crystals were characterized by means of elemental analysis, and IR, and ¹H‐ and ¹³C‐NMR spectroscopy. Also, thermal analyses under air atmosphere and X‐ray crystallography have been performed on these structures. X‐Ray single‐crystal analyses revealed that these networks contain large vacant voids. These structures, [(DABTZ)₂(bipy)] and [(DABTZ)₂(bk)(MeOH)], crystallized in monoclinic and triclinic forms with space groups of P2₁/c and P , respectively. The self‐assembly of these compounds in the solid state is likely caused by both H‐bonding and π? π stacking.     

The layered compound poly[μ2‐4,4′‐bipyridyl‐di‐μ2‐chlorido‐mercury(II)]

The title compound, [HgCl₂(C₁₀H₈N₂)]_n, features two‐dimensional [HgCl₂(4,4′‐bipy)]_n neutral networks (4,4′‐bipy is 4,4′‐bipyridine), based on an octahedral Hg atom coordinated by four μ₂‐Cl atoms and two μ₂‐4,4′‐bipy ligands in trans positions, yielding a HgCl₄N₂ octahedron. The structure has mmm symmetry about the Hg atoms, with most of the atoms on at least one mirror plane, but the unsubstituted C atoms of the 4,4′‐bipy rings are disordered across a mirror plane. Photoluminescent investigations reveal that the title compound displays a strong emission in the green region, which probably originates from a ligand‐to‐ligand charge‐transfer transition.     

A threefold interpenetrated two‐dimensional zinc(II) supramolecular architecture based on 3‐nitrobenzoic acid and 4,4′‐bipyridine

With regard to crystal engineering, building block or modular assembly methodologies have shown great success in the design and construction of metal–organic coordination polymers. The critical factor for the construction of coordination polymers is the rational choice of the organic building blocks and the metal centre. The reaction of Zn(OAc)₂·2H₂O (OAc is acetate) with 3‐nitrobenzoic acid (HNBA) and 4,4′‐bipyridine (4,4′‐bipy) under hydrothermal conditions produced a two‐dimensional zinc(II) supramolecular architecture, catena‐poly[[bis(3‐nitrobenzoato‐κ²O,O′)zinc(II)]‐μ‐4,4′‐bipyridine‐κ²N:N′], [Zn(C₇H₄NO₄)₂(C₁₀H₈N₂)]_n or [Zn(NBA)₂(4,4′‐bipy)]_n, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray diffraction analysis. The Zn^II ions are connected by the 4,4′‐bipy ligands to form a one‐dimensional zigzag chain and the chains are decorated with anionic NBA ligands which interact further through aromatic π–π stacking interactions, expanding the structure into a threefold interpenetrated two‐dimensional supramolecular architecture. The solid‐state fluorescence analysis indicates a slight blue shift compared with pure 4,4′‐bipyridine and HNBA.