Selective Separation of Aliphatic Nitriles by Employing a Two‐Dimensional Interdigitated Coordination Polymer

A room‐temperature slow diffusion reaction of the metal nitrates [M=Zn^II and Co^II] with 5‐azido isophthalic acid (AIPA) and 1,4‐bis(4‐pyridyl)‐2,3‐diaza‐1,3‐butadiene (BPDB) resulted in a new two‐dimensional interdigitated coordination polymer, [M(C₈H₃N₃O₄)(C₁₂H₁₀N₄)] ⋅ DMF [DMF=dimethyl formamide (C₃H₇NO)]. The non‐bonded DMF molecules were found to exchange through a single‐crystal to single‐crystal (SCSC) fashion with many aliphatic nitrile compounds. More importantly, the present compound, I⋅DMF (Zn) appears to absorb cis ‐crotononitrile selectively from the cis /trans mixture as well as a mixture containing the structural isomer (allylnitrile). It also preferentially absorbs propionitrile from an equimolar mixture of acetonitrile, propionitrile, and butyronitrile (1:2:1). The cobalt compound exhibits anti‐ferromagnetic behavior.     

The crystal structure,luminescence and nitrobenzene‐sensing properties of a two‐dimensional MnII coordination polymer based on 2,6‐bis(imidazol‐1‐yl)pyridine

A two‐dimensional Mn^II coordination polymer (CP), poly[bis[μ₂‐2,6‐bis(imidazol‐1‐yl)pyridine‐κ²N³:N^3′]bis(thiocyanato‐κN)manganese] [Mn(NCS)₂(C₁₁H₉N₅)₂]_n, (I), has been obtained by the self‐assembly reaction of Mn(ClO₄)₂·6H₂O, NH₄SCN and bent 2,6‐bis(imidazol‐1‐yl)pyridine (2,6‐bip). CP (I) was characterized by FT–IR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. The crystal structure features a unique two‐dimensional (4,4) network with one‐dimensional channels. The luminescence and nitrobenzene‐sensing properties were explored in a DMF suspension, revealing that CP (I) shows a strong luminescence emission and is highly sensitive for nitrobenzene detection.     

Effect of Bulkiness on Reversible Substitution Reaction at MnII Center with Concomitant Movement of the Lattice DMF: Observation through Single‐Crystal to Single‐Crystal Fashion

The porous coordination polymer ({[Mn(L)H₂O](H₂O)_1.5(dmf)}_n, 1 ) (DMF=N,N‐dimethylformamide) exhibits variety of substitution reactions along with movement of lattice DMF molecule depending upon bulkiness of the external guest molecules. If pyridine or 4‐picoline is used as a guest, both lattice and coordinated solvent molecules are simultaneously substituted (complexes 6 and 7 , respectively). If a bulky guest like aniline is used, a partial substitution at the metal centers and full substitution at the channels takes place (complex 8 ). If the guest is 2‐picoline (by varying the position of bulky methyl group with respect to donor N atom), one Mn^II center is substituted by 2‐picoline, whereas the remaining center is substituted by a DMF molecule that migrates from the channel to the metal center (complex 9 ). Here, the lattice solvent molecules are substituted by 2‐picoline molecules. For the case of other bulky guests like benzonitrile or 2,6‐lutidine, both the metal centers are substituted by two DMF molecules, again migrating from the channel, and the lattice solvent molecules are substituted by these guest molecules (complex 10 and 11 , respectively). A preferential substitution of pyridine over benzonitrile (complex 12 ) at the metal centers is observed only when the molar ratio of PhCN:Py is 95:5 or less. For the case of an aliphatic dimethylaminoacetonitrile guest, the metal centers remain unsubstituted (complex 13 ); rather substitutions of the lattice solvents by the guest molecules take place. All these phenomena are observed through single crystal to single crystal (SC–SC) phenomena.     

A one‐dimensional coordination polymer of 5‐[(imidazol‐1‐yl)methyl]benzene‐1,3‐dicarboxylic acid with CuII cations

5‐[(Imidazol‐1‐yl)methyl]benzene‐1,3‐dicarboxylic acid (H₂L) was synthesized and the dimethylformamide‐ and dimethylacetamide‐solvated structures of its adducts with Cu^II, namely catena‐poly[[copper(II)‐bis[μ‐3‐carboxy‐5‐[(imidazol‐1‐yl)methyl]benzoato]] dimethylformamide disolvate], {[Cu(C₁₂H₉N₂O₄)₂]·2C₃H₇NO}_n, (I), and catena‐poly[[copper(II)‐bis[μ‐3‐carboxy‐5‐[(imidazol‐1‐yl)methyl]benzoato]] dimethylacetamide disolvate], {[Cu(C₁₂H₉N₂O₄)₂]·2C₄H₉NO}_n, (II), the formation of which are associated with mono‐deprotonation of H₂L. The two structures are isomorphous and isometric. They consist of one‐dimensional coordination polymers of the organic ligand with Cu^II in a 2:1 ratio, [Cu(μ‐HL)₂]_n, crystallizing as the dimethylformamide (DMF) or dimethylacetamide (DMA) disolvates. The Cu^II cations are characterized by a coordination number of six, being located on centres of crystallographic inversion. In the polymeric chains, each Cu^II cation is linked to four neighbouring HL⁻ ligands, and the organic ligand is coordinated via Cu—O and Cu—N bonds to two Cu^II cations. In the corresponding crystal structures of (I) and (II), the coordination chains, aligned parallel to the c axis, are further interlinked by strong hydrogen bonds between the noncoordinated carboxy groups in one array and the coordinated carboxylate groups of neighbouring chains. Molecules of DMF and DMA (disordered) are accommodated at the interface between adjacent polymeric assemblies. This report provides the first structural evidence for the formation of coordination polymers with H₂Lvia multiple metal–ligand bonds through both carboxylate and imidazole groups.     

二(2-苯基-8-羟基喹啉)锌及其衍生物的电子光谱性质的含时密度泛函理论研究

采用从头算(ab initio)和密度泛函理论(DFT B3LYP)方法。对二(2-苯基-8-羟基喹啉)锌(Zn(qPh)₂)及其衍生物的基态结构进行优化，同时用ab initio HF单激发组态相互作用(CIS)法在6-31G基组上优化其最低激发单重态几何结构，用含时密度泛函理论(TD-DFT/B3LYP)及6-31G基组计算吸收和发射光谱。计算表明，该类物质电子在基态与激发态间的跃迁，主要是电子云分布由定域化向离域化的转变。吸收及发射光谱的计算值与实验值基本符合。该类化合物的电子亲和能较大，都是优良的电子传输材料，改变中心金属原子对配合物光谱性质影响不大。而羟基氧被硫原子取代后，化合物的吸收光谱产生明显红移。     

High‐Contrast Red–Green–Blue Tricolor Fluorescence Switching in Bicomponent Molecular Film

Highly efficient red–green–blue (RGB) tricolor luminescence switching was demonstrated in a bicomponent solid film consisting of (2Z,2′Z)‐2,2′‐(1,4‐phenylene)bis(3‐(4‐butoxyphenyl)acrylonitrile) (DBDCS) and (2Z,2′Z)‐3,3′‐(2,5‐bis(6‐(9H‐carbazol‐9‐yl)hexyloxy)‐1,4‐phenylene)bis(2‐(3,5‐bis(trifluoromethyl)phenyl)acrylonitrile) (m‐BHCDCS). Reversible RGB luminescence switching with a high ratiometric color contrast (λ_em=594, 527, 458 nm for red, green, and blue, respectively) was realized by different external stimuli such as heat, solvent vapor exposure, and mechanical force. It was shown that Förster resonance energy transfer in the bicomponent mixture could be efficiently switched on and off through supramolecular control.     

The Synthesis of 1,4‐Bis[N‐(4/6‐Substituted Benzothiazole‐2‐yl)‐N′‐Glycosylguanidino]Benzenes

The starting material O‐protected glycosyl isothiocyanate ( 1?3 ) was refluxed with 1,4‐diaminobenzene in CHCl₃ under nitrogen atmosphere to give 1,4‐bis(N‐glycosyl)thioureidobenzene ( 4?6 ). Then 1,4‐bis[N‐(4/6‐substituted benzothiazole‐2‐yl)‐N′‐glycosylguanidino]benzenes ( 8a?8e , 9a?9e , 10a?10e ) were obtained in good yield by reaction of compounds ( 4?6 ) with 2‐amino‐4/6‐benzothizoles ( 7a?7e ) and HgCl₂ in the presence of TEA in DMF. The structures of all 18 new compounds were confirmed by IR, ¹H NMR, LC‐MS and elemental analysis. The bioactivity of anti‐HIV‐1 protease (HIV‐1 PR) and against angiotensin converting enzyme (ACE) have been evaluated.     

A self‐penetrated three‐dimensional zinc(II) coordination framework based on 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoic acid and 1,3‐bis[(imidazol‐1‐yl)methyl]benzene ligands: synthesis,structure and properties

With the rapid development of metal–organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen‐containing ligands are employed to construct MOFs with fascinating structures. 4,4′,4′′‐(1,3,5‐Triazine‐2,4,6‐triyl)tribenzoic acid (H₃TATB) and the bidentate nitrogen‐containing ligand 1,3‐bis[(imidazol‐1‐yl)methyl]benzene (bib) were selected to prepare a novel Zn^II‐MOF under solvothermal conditions, namely poly[[tris{μ‐1,3‐bis[(imidazol‐1‐yl)methyl]benzene}bis[μ₃‐4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn₃(C₂₄H₁₂N₃O₆)₂(C₁₄H₁₄N₄)₃]·2C₃H₇NO·3H₂O}_n ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction, IR spectroscopy and powder X‐ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single‐crystal X‐ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent Zn^II centres, two 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoate (TATB^3?) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each Zn^II centre is four‐coordinated and displays a distorted tetrahedral coordination geometry. The Zn^II centres are connected by TATB^3? anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link Zn^II centres to give a helical Zn–bib–Zn chain. Furthermore, adjacent ladders are bridged by Zn–bib–Zn chains to form a fascinating three‐dimensional self‐penetrated framework with the short Schläfli symbol 6⁵·7·8¹³·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr⁴⁺ and Cu²⁺ ions.     

A helical coordination polymer of zinc(II), 4‐hydroxybenzohydrazide and sulfate ions

In the structure of the novel zinc complex catena‐poly[[diaqua(4‐hydroxybenzohydrazide)zinc(II)]‐μ‐sulfato], [Zn(SO₄)(C₇H₈N₂O₂)(H₂O)₂]_n, the complex cations are linked by sulfate counter‐ions into helical polymeric chains extending along the b axis. Each helix is stabilized by six intrachain hydrogen bonds involving stronger O—H...O (1.83–2.06 Å) and weaker N—H...O (2.20–2.49 Å) interactions. The Zn^II atom displays a distorted octahedral geometry formed by the 4‐hydroxybenzohydrazide ligand, two water molecules and two SO₄²⁻ ions, which is very similar to the metal‐atom environment in a previously reported Co^II complex [Zasłona, Drożdżewski & Kubiak (2010). J. Mol. Struct. 982 , 1–8], especially the Zn—O and Zn—N bond lengths of 2.0453 (12)–2.1602 (9) and 2.1118 (12) Å, respectively.     

Structural analysis of interpenetrated methyl‐modified MOF‐5 and its gas‐adsorption properties

The first example of an interpenetrated methyl‐modified MOF‐5 with the formula Zn₄O(DMBDC)₃(DMF)₂, where DMBDC^2? is 2,5‐dimethylbenzene‐1,4‐dicarboxylate and DMF is N,N‐dimethylformamide (henceforth denoted as Me₂MOF‐5‐int ), namely, poly[tris(μ₄‐2,5‐dimethylbenzene‐1,4‐dicarboxylato)bis(N,N‐dimethylformamide)‐μ₄‐oxido‐tetrazinc(II)], [Zn₄(C₁₀H₈O₄)₃O(C₃H₇NO)₂]_n, has been obtained from a solvothermal synthesis of 2,5‐dimethylbenzene‐1,4‐dicarboxylic acid and Zn(NO₃)₂·6H₂O in DMF. A systematic study revealed that the choice of solvent is of critical importance for the synthesis of phase‐pure Me₂MOF‐5‐int , which was thoroughly characterized by single‐crystal and powder X‐ray diffraction (PXRD), as well as by gas‐adsorption analyses. The Brunauer–Emmett–Teller surface area of Me₂MOF‐5‐int (660 m² g^?1), determined by N₂ adsorption, is much lower than that of nonpenetrated Me₂MOF‐5 (2420 m² g^?1). However, Me₂MOF‐5‐int displays an H₂ uptake capacity of 1.26 wt% at 77 K and 1.0 bar, which is comparable to that of non‐interpenetrated Me₂MOF‐5 (1.51 wt%).     

Systematische Studie zu den Koordinationseigenschaften des Guanidin‐Liganden Bis(tetramethylguanidino)propan mit den Metallen Mangan,Cobalt, Nickel,Zink, Cadmium,Quecksilber und Silber

The transition metal complexes with the ligand 1,3‐bis(N,N,N′,N′‐tetramethylguanidino)propane (btmgp), [Mn(btmgp)Br₂] ( 1 ), [Co(btmgp)Cl₂] ( 2 ), [Ni(btmgp)I₂] ( 3 ), [Zn(btmgp)Cl₂] ( 4 ), [Zn(btmgp)(O₂CCH₃)₂] ( 5 ), [Cd(btmgp)Cl₂] ( 6 ), [Hg(btmgp)Cl₂] ( 7 ) and [Ag₂(btmgp)₂][ClO₄]₂·2MeCN ( 8 ), were prepared and characterised for the first time. The stoichiometric reaction of the corresponding water‐free metal salts with the ligand btmgp in dry MeCN or THF resulted in the straightforward formation of the mononuclear complexes 1 – 7 and the binuclear complex 8 . In complexes with M^II the metal ion shows a distorted tetrahedral coordination whereas in 8 , the coordination of the M^I ion is almost linear. The coordination behavior of btmgp and resulting structural parameters of the corresponding complexes were discussed in an comparative approach together with already described complexes of btmgp and the bisguanidine ligand N¹,N²‐bis(1,3‐dimethylimidazolidin‐2‐ylidene)‐ethane‐1,2‐diamine (DMEG₂e), respectively.     

Silver(I)‐N‐heterocyclic carbene complexes of bis‐imidazol‐2‐ylidenes having different aromatic‐spacers: synthesis,crystal structure,and in vitro antimicrobial and anticancer studies

A series of Ag(I) complexes ( 6 , 7 , 8 , 9 ) derived from imidazol‐2‐ylidenes was synthesized by reacting Ag₂O with an o‐, m‐, p‐xylyl or 1,3,5‐triazine‐linked imidazolium salts ( 1 , 2 , 3 , 4 ) and then characterizing these using various spectro‐analytical techniques. Additionally, triazine‐linked bis‐imidazolium salt 5 was characterized using the single‐crystal X‐ray diffraction method. Complexes 6–9 were formed from the N‐heterocyclic carbene ligand precursors 1–3 as PF₆^‐ salts in good yields. Conversely, salt 5 does not form Ag(I) complex even under various reaction conditions. Using ampicillin as a standard, complexes 6–9 were tested against bacteria strains Escherichia coli and Staphylococcus aureus as Gram‐negative and Gram‐positive bacteria, respectively, showing potent antimicrobial activities against the tested bacteria even at minimum inhibition concentration and bacterial concentration levels. Furthermore, the potential anticancer activities of the reported complexes were evaluated against the human colorectal cancer (HCT 116) cell lines, using 5‐fluorouracil as a standard drug. The highest anticancer activities were observed for complex 8 with an IC₅₀ value of 3.4 μm , whereas the lowest was observed for complex 9 with an IC₅₀ value of 18.1 μm . Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of Zinc(II) on the Luminescence of Europium(III) in Complexes Containing β‐Diketone and Schiff Bases

The UV, excitation, and luminescence spectra of tris(pivaloyltrifluoroacetonato)europium(III) ([Eu(pta)₃]; Hpta=1,1,1‐trifluoro‐5,5‐dimethylhexane‐2,4‐dione=HA) were measured in the presence of bis(salicylidene)trimethylenediamine (H₂saltn), bis[5‐(tert‐butyl)salicylidene]trimethylenediamine (H₂(^tBu)saltn), or bis(salicylidene)cyclohexane‐1,2‐diyldiamine (H₂salchn), and the corresponding Zn^II complexes [ZnB] (B=Schiff base). The excitation and luminescence spectra of the solution containing [Eu(pta)₃] and [Zn(salchn)] exhibited much stronger intensities than those of solutions containing the other [ZnB] complexes. The introduction of a ^tBu group into the Schiff base was not effective in sensitizing the luminescence of [Eu(pta)₃]. The luminescence spectrum of [ZnB] showed a band around 450 nm. The intensity decreased in the presence of [Eu(pta)₃], reflecting complexation between [Eu(pta)₃] and [ZnB]. On the basis of the change in intensity against the concentration of [ZnB], stability constants were determined for [Eu(pta)₃Zn(saltn)], [Eu(pta)₃Zn{(^tBu)saltn}], and [Eu(pta)₃Zn(salchn)] as 4.13, 4.9 and 5.56, respectively (log , where =[[Eu(pta)₃ZnB]]([[Eu(pta)₃]][[ZnB]])^?1). The quantum yields of these binuclear complexes were determined as 0.15, 0.11, and 0.035, although [Eu(pta)₃Zn(salchn)] revealed the strongest luminescence at 613 nm. The results of X‐ray diffraction analysis for [Eu(pta)₃Zn(saltn)] showed that Zn^II had a coordination number of five and was bridged with Eu^III by three donor O‐atoms, i.e., two from the salicylidene moieties and one from the ketonato group pta.     

Rational design of zinc-organic coordination polymers directed by N-donor co-ligands

A family of Zn^II‐based metal–organic coordination polymers (MOCPs) [Zn(L)(imid)₂] ( 1 ), [Zn(L)(2,2′‐bpy)] ( 2 ), [Zn₂(L)₂(Py)₃] ( 3 ), [Zn(L)(DPP)]?DMF ( 4 ), [Zn(L)(DPEA)] ( 5 ), [Zn₂(L)₂(4,4′‐bpy)] ( 6 ), [Zn(L)(3,4′‐DPEE)]?DMF ( 7 ), and [Zn₃(L)₃(3,4′‐DPEE)₂]?DMF ( 8 ) (L=dithieno[3,2‐b:2′,3′‐e]benzene‐2,6‐dicarboxylic acid, imid=imidazole, bpy=bipyridine, Py=pyridine, DPP=1,3‐di(pyridin‐4‐yl)propane, DPEA=1,2‐di(pyridin‐4‐yl)ethane, and DPEE=(E)‐3,4′‐(ethene‐1,2‐diyl)dipyridine) have been rationally designed and generated in the solvothermal reaction systems of the new conjugated thiophene derivative L, Zn(ClO₄)₂?6 H₂O, and seven different aromatic N‐donor co‐ligands separately. These N‐donor compounds were carefully selected and employed in the crystal preparation of the eight MOCPs as structure‐directing co‐ligands owing to their structural specialties and habitual coordination fashions. Among these MOCPs, compounds 1 – 3 are 1D polymers with different chain structures. Compounds 4 , 7 , and 8 are 2D structures, in which 4 has two sets of twofold interpenetrating layers, whereas 7 and 8 are both built from three independent sheets. Compounds 5 and 6 are 3D frameworks, in which 5 exhibits a fivefold interpenetrating diamondoid network, whereas 6 shows a typical twofold interpenetrating pillared layer structure with nanoscale channels. The photoluminescent properties of these MOCPs, including excitation, emission, and radiactive lifetime, have also been investigated to help us tentatively understand their structure–property relationships.     

Syntheses and Structural Characterization of 1D Chain and 1D Ladder Coordination Polymers Assembled from Exo‐bidentate Imidazolyl Ligands

Five novel coordination polymers, [(Cu(L¹)₂OH) · Cl · 3H₂O] ( 1 ) [L¹ = bis(N‐imidazolyl)methane], [Cd(L¹)₂(NCS)₂] ( 2 ), [Zn(L¹)₂(NCS)₂] ( 3 ), [Cu(L¹)₂(NO₃)₂] ( 4 ), and [Cu(L²)_1.5(NCS)₂] ( 5 ) [L² = 1,4‐bis(N‐imidazolyl)butane] were obtained from self‐assembly of the corresponding metal salts with flexible ligands and their structures were fully characterized by X‐ray diffraction (XRD) analysis, Fourier Transform Infrared (FT‐IR) spectroscopy, elemental analysis and thermogravimetric (TGA) measurements. X‐ray diffraction analyses revealed that complexes 1 , 2 , 3 , and 4 exhibit 1D double‐stranded chain structures, which result from doubly bridged [CuOH], [M(NCS)₂] (M = Cd, Zn), and [Cu(NO₃)₂] units, respectively. The polymeric copper complex 5 displays 1D ladder structure., These complexes, with the exception of complex 1 , are stable up to 300 °C.     

Structural variation from linear,layer to 3D framework: Syntheses,structures and luminescence

Self‐assembly of Zn (II) or Cd (II) nitrates, flexible bis (pyridyl)‐diamine, as well as arenesulfonic acids, leads to the formation of ten coordination polymers, namely, [Zn(L1)(H₂O)₃]·2(p‐TS)·2H₂O ( 1 ), [Zn(L1)(H₂O)₂]·2(p‐TS)·2H₂O ( 2 ), [Zn(L1)₂(p‐TS)₂] ( 3 ), [Zn(H₂L1)(H₂O)₄]·2(1,5‐NDS)·2H₂O ( 4 ), [Zn(H₂L2)(H₂O)₄]·2(1,5‐NDS)·4MeOH ( 5 ), [Cd(L1)(p‐TS)(NO₃)]·H₂O ( 6 ), [Cd(L1)(1,5 ‐NDS)_0.5(H₂O)]·0.5(1,5‐NDS)·H₂O ( 7 ), [Cd(L2)(H₂O)₂]·(p‐TS)·(NO₃)·3H₂O ( 8 ), [Cd(L2)(1,5‐NDS)] ( 9 ) and [Cd(L2)(1,5‐NDS)]·MeOH ( 10 ) (L1 = N,N′‐bis (pyridin‐4‐ylmethyl) ethane‐1,2‐diamine, L2 = N,N′‐bis (pyridin‐3‐ylmethy l)ethane‐1,2‐diamine, p‐HTS = p‐toluenesulfonic acid, 1,5‐H₂NDS = 1,5‐naphthalene disulfonic acid), which have been characterized by elemental analysis, IR, TG, PL, powder and single‐crystal X‐ray diffraction. Complexes 1 , 4 , 5 and 6 present linear or zigzag chain structures accomplished by the interconnection of adjacent M (II) cations through L1 ligands or protonated H₂L1²⁺/H₂L2²⁺ cations, while complexes 2 , 3 and 8 show similar (4,4) layer motifs constructed from the connection of M (II) cations through L1 and L2. The same coordination modes of L1 and L2 in complexes 7 and 9 join adjacent Cd (II) cations to form double chain structures, which are further connected by bis‐monodentate 1,5‐NDS^2? dianions into different (6,3) and (4,4) layer motifs. The L2 molecules in complex 10 join adjacent Cd (II) cations together with 1,5‐NDS^2? dianions to form 3D network with hxl topology. Therefore, the diverse coordination modes of the bis (pyridyl) ligand with chelating spacer and the feature of different arenesulfonate anions can effectively influence the architectures of these complexes. Luminescent investigation reveals that the emission maximum of these complexes varies from 374 to 448 nm in the solid state at room temperature, in which complexes 4 , 5 , 7 , 9 and 10 show average luminescence lifetimes from 7.20 to 14.82 ns. Moreover, photocatalytic properties of complexes 7–10 towards Methylene blue under Xe lamp irradiation are also discussed.     

A three‐dimensional manganese(II) metal–organic framework based on 5‐methoxybenzene‐1,3‐dicarboxylic acid and exhibiting a pts net

The solvothermal reaction of MnCl₂·H₂O and 5‐methoxybenzene‐1,3‐dicarboxylic acid (MeO‐m‐H₂BDC) led to a three‐dimensional Mn^II metal–organic framework, namely poly[(dimethylformamide‐κO)(μ₄‐5‐methoxybenzene‐1,3‐dicarboxylato‐κ⁴O¹:O^1′:O³,O^3′:O³)manganese(II)], [Mn(C₉H₆O₅)(C₃H₇NO)]_n or [Mn(MeO‐m‐BDC)(DMF)]_n (DMF is dimethylformamide). The Mn^II atom is six‐coordinated and exhibits a distorted octahedral geometry formed by five carboxylate O atoms from four different MeO‐m‐BDC²⁻ anionic ligands and by one DMF O atom. The three‐dimensional framework of (I) formed by the bridging MeO‐m‐BDC²⁻ ligands and the Mn^II atoms exhibits a pts topological network when MeO‐m‐BDC²⁻ and Mn^II are viewed as four‐connected nodes.     

Interactions between metal chlorides and poly(vinyl pyrrolidone) in concentrated solutionsand solid‐state films

The rheological behavior of poly(vinyl pyrrolidone) (PVP)/N,N‐dimethylformamide (DMF) solutions containing metal chlorides (LiCl, CaCl₂, and CoCl₂) were investigated, and the results showed that the nature of the metal ions and their concentration had an obvious effect on the steady‐state rheological behavior of PVP–DMF solutions with different molecular weights. The apparent viscosity of the PVP–DMF solutions increased with an increasing metal‐ion concentration, and the viscosity increment was dependent on the metal‐ion variety_. For a CaCl₂‐containing PVP–DMF solution, for example, the critical shear rate at the onset of shear thinning became smaller with increasing CaCl₂ concentration. It was believed that multiple interactions among metal ions, carbonyl groups of PVP, and amide groups in DMF determined the solution properties of these complex fluids; therefore, ¹³C NMR spectroscopy was used to detect the interactions in systems of PVP–CaCl₂–DMF and PVP–LiCl–DMF solutions. NMR data showed that there were obvious interactions between the metal ions and the carbonyl groups of the PVP segments in the DMF solutions. Furthermore, IR spectra of the PVP/metal chloride composites demonstrated that the interaction between the metal ions and carbonyl groups in the PVP unit occurred and that the PVP chain underwent conformational variations with the metal‐ion concentration. DSC results indicated that the glass transition temperatures of the PVP/metal chloride composites increased with the addition of metal ions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1589–1598, 2007     

Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1,3‐Selenazinane and 1,3‐Selenazinanone Derivatives

The reaction of the intermediate ketene N,Se‐hemiacetal 3 , prepared from cyanomethylene derivatives 1 by treatment with Et₃N and aryl isoselenocyanates 2 , with bis‐electrophiles 6, 7, 9 , and 11 in DMF affords tetrahydro‐1H‐1,3‐selenazine (=1,3‐selenazinane) derivatives 8, 10 , and 12 in good yield (Scheme 2 and Tables 1–3). Chemical and spectroscopic evidence for the structures of the new compounds are described. The structures of 8d and 12e are established by X‐ray crystallography (Figs. 1 and 2).     

Effect of Functionalized Groups on Gas‐Adsorption Properties: Syntheses of Functionalized Microporous Metal–Organic Frameworks and Their High Gas‐Storage Capacity

The microporous metal–organic framework (MMOF) Zn₄O(L1)₂ ? 9 DMF ? 9 H₂O ( 1‐H ) and its functionalized derivatives Zn₄O(L1‐CH₃)₂ ? 9 DMF ? 9 H₂O ( 2‐CH₃ ) and Zn₄O(L1‐Cl)₂ ? 9 DMF ? 9 H₂O ( 3‐Cl ) have been synthesized and characterized (H₃L1=4‐[N,N‐bis(4‐methylbenzoic acid)amino]benzoic acid, H₃L1‐CH₃=4‐[N,N‐bis(4‐methylbenzoic acid)amino]‐2‐methylbenzoic acid, H₃L1‐Cl=4‐[N,N‐bis(4‐methylbenzoic acid)amino]‐2‐chlorobenzoic acid). Single‐crystal X‐ray diffraction analyses confirmed that the two functionalized MMOFs are isostructural to their parent MMOF, and are twofold interpenetrated three‐dimensional (3D) microporous frameworks. All of the samples possess enduring porosity with Langmuir surface areas over 1950 cm² g^?1. Their pore volumes and surface areas decrease in the order 1‐H > 2‐CH₃ > 3‐Cl . Gas‐adsorption studies show that the H₂ uptakes of these samples are among the highest of the MMOFs (2.37 wt % for 3‐Cl at 77 K and 1 bar), although their structures are interpenetrating. Furthermore, this work reveals that the adsorbate–adsorbent interaction plays a more important role in the gas‐adsorption properties of these samples at low pressure, whereas the effects of the pore volumes and surface areas dominate the gas‐adsorption properties at high pressure.