Metal‐ and Substituent‐Dependent Structural Diversity in ­Cobalt and Nickel Isophthalate Coordination Polymers with Bis(4‐pyridylformyl)piperazine Tethers

Hydrothermal reactions of nickel or cobalt nitrate with the dipyridylamide ligand bis(4‐pyridylformyl)piperazine (4‐bpfp) and either 5‐methoxyisophthalate (H₂omeip) or 5‐methylisophthalate (H₂mip) afforded a series of coordination polymers that were structurally characterized by single‐crystal X‐ray diffraction. Different synthetic conditions afforded the 1D chain phase {[Ni(Homeip)₂(H₂omeip)(bpfp)] · 2H₂O}_n ( 1 ) or the mutually inclined interpenetrated (4, 4) grid system in {[Ni(omeip)(bpfp)(H₂O)] · 2H₂O}_n ( 2 ). The analogous cobalt phase {[Co(omeip)(bpfp)] · 3H₂O}_n ( 3 ) lacks bound water molecules, which enforces a non‐interpenetrated (4, 4) grid structure based on {Co₂(OCO)₂} dinuclear clusters. Similar clusters are seen in {[Co(mip)(bpfp)(H₂O)₂] · 3.5H₂O}_n ( 4 ), which manifests a 1D ribbon structural motif. Its nickel congener {[Ni(Hmip)₂(bpfp)(H₂O)₂] · 2H₂mip}_n ( 5 ) also shows a 1D chain motif. A variable temperature magnetic susceptibility study indicates antiferromagnetic coupling within the dimeric units in 3 and 4 concomitant with single ion effects. Additionally, thermal degradation properties of these new materials are described.     

Structural investigation of one‐ and two‐dimensional coordination polymers based on cobalt–bis(dioxolene) units and 1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane

The combination of cobalt, 3,5‐di‐tert‐butyldioxolene (3,5‐dbdiox) and 1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane (tpch) yields two coordination polymers with different connectivities, i.e. a one‐dimensional zigzag chain and a two‐dimensional sheet. Poly[[bis(3,5‐di‐tert‐butylbenzene‐1,2‐diolato)bis(1,5‐di‐tert‐butyl‐4‐oxocyclohexa‐2,5‐dien‐1‐yl‐3‐olato)[μ₄‐1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane]cobalt(III)]–ethanol–water 1/7/5], {[Co₂(C₁₄H₂₀O₂)₄(C₂₆H₂₄N₄O)]·7C₂H₅OH·5H₂O}_n or {[Co₂(3,5‐dbdiox)₄(tpch)}·7EtOH·5H₂O}_n, is the second structurally characterized example of a two‐dimensional coordination polymer based on linked {Co(3,5‐dbdiox)₂} units. Variable‐temperature single‐crystal X‐ray diffraction studies suggest that catena‐poly[[[(3,5‐di‐tert‐butylbenzene‐1,2‐diolato)(1,5‐di‐tert‐butyl‐4‐oxocyclohexa‐2,5‐dien‐1‐yl‐3‐olato)cobalt(III)]‐μ‐1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane]–ethanol–water (1/1/5)], {[Co(C₁₄H₂₀O₂)₂(C₂₆H₂₄N₄O)]·C₂H₅OH·5H₂O}_n or {[Co(3,5‐dbdiox)₂(tpch)]·EtOH·5H₂O}_n, undergoes a temperature‐induced valence tautomeric interconversion.     

Effect of Flexible Bis(Benzimidazole) Ligands on the Structures of Cobalt(II) Coordination Polymers Derived from 2,6‐Naphthalenedicarboxylic Acid

The cobalt(II) coordination polymers{[Co(L1)(nda)] · 2H₂O}_n ( 1 ) and [Co(L2)₂(nda)]_n ( 2 ), [L1 = 1,2‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, L2 = 1,4‐bis(5,6‐dimethylbenzimidazol‐1‐ylmethyl)benzene, H₂nda = 2,6‐naphthalenedicarboxylic acid] were hydrothermally synthesized by self‐assembly of cobalt chloride with H₂nda and different semi‐rigid bis(benzimidazole) derivatives and characterized by IR spectroscopy, elemental analysis, and X‐ray single‐crystal diffraction. Complex 1 displays a 2D layer with (4,4) topology, complex 2 exhibits a 1D infinite chain structure, both complexes were further packed into 3D and 2D supramolecular architectures by weak hydrogen bonding. The catalytic activities of the complexes for degradation of Congo red in a Fenton‐like process are presented. In addition, the electrochemical and electrocatalytical behavior of CPEs modified with both cobalt complexes (Co‐CPE) were investigated in detail.     

Three Transition Metal(II) Coordination Polymers Constructed by a Semi‐rigid Bis‐pyridyl‐bis‐amide and Dicarboxylates Mixed Ligands: Assembly,Structures and Properties

Three coordination polymers, namely [Co(BDC)( L )] · H₂O ( 1 ), [Co(NPH)( L )] · H₂O ( 2 ), and [Ni(NPH)( L )(H₂O)₃] · H₂O ( 3 ) [H₂BDC = 1, 3‐benzenedicarboxylic acid, H₂NPH = 3‐nitrophthalic acid, L = N,N′‐bis(3‐pyridyl)‐terephthalamide] were hydrothermally synthesized by self‐assembly of cobalt/nickel chloride with a semi‐rigid bis‐pyridyl‐bis‐amide ligand and two aromatic dicarboxylic acids. Single crystal X‐ray diffraction analyses revealed that complexes 1 and 2 are two‐dimensional (2D) coordination polymers containing a one‐dimensional (1D) ribbon‐like Co‐dicarboxylate chain and a 1D zigzag Co‐ L chain. Although the coordination numbers of Co^II ions and the coordination modes of two dicarboxylates are different in complexes 1 and 2 , they have a similar 3, 5‐connected {4².6⁷.8}{4².6} topology. In complex 3 , the adjacent Ni^II ions are linked by L ligands to form a 1D polymeric chain, whereas the 1D chains does not extend into a higher‐dimensional structure due to the ligand NPH with monodentate coordination mode. The adjacent layers of complexes 1 and 2 and the adjacent chains of 3 are further linked by hydrogen bonding interactions to form 3D supramolecular networks. Moreover, the thermal stabilities, fluorescent properties, and photocatalytic activities of complexes 1 – 3 were studied.     

Synthesis,Structures, and Photocatalytic Properties of Zinc(II) and Cobalt(II) Supramolecular Complexes Constructed with Flexible Bis(thiabendazole) and Dicarboxylate Linkers

Three coordination complexes, namely, [Zn(btbp)(3‐npa)]_n ( 1 ), [Co(btbh)(3‐npa)]_n ( 2 ), and {[Co(btbb)(5‐nipa)(H₂O)] · H₂O}_n ( 3 ) (btbp = 1,3‐bis(thiabendazole)propane, btbh = 1,6‐bis(thiabendazole)hexane, btbb = 1,4‐bis(thiabendazole)butane, 3‐H₂npa = 3‐nitrophthalic acid and 5‐H₂nipa = 5‐nitroisophthalic acid) were synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as by single‐crystal X‐ray diffraction. Complex 1 features a fascinating meso‐helical chain, which is further extended into a 2D supramolecular framework involving π ··· π stacking interactions. Complexes 2 and 3 show dinuclear structures. Complex 2 is further connected through C–H ··· O hydrogen bonding interactions to afford a 2D supramolecular layer, whereas complex 3 is further extended to a rare 2‐nodal (3,4)‐connected supramolecular sheet with a point symbol of {3.4².5.6.7}₂{3.8²} by O–H ··· O hydrogen bonding interactions. The electrochemical behaviors of the two cobalt complexes 2 and 3 were reported. Moreover, the luminescent properties for 1 and the photocatalytic properties for the complexes were investigated.     

Syntheses,Characterization, and Electrochemical Lithium‐Ion Storage Properties of Two Cobalt(II) Coordination Polymers Containing 5‐Hydroxyisophthalic Acid and Bis‐benzoimidazole Ligands

Two cobalt(II) coordination polymers, namely {[Co(HO‐BDC)(bbe)] · (H₂O)}_n ( 1 ), and {[Co(O‐BDC)(bbp)] · (H₂O)}_n ( 2 ) (HO‐H₂BDC = 5‐hydroxyisophthalic acid, bbe = 1, 2‐bis(benzoimidazol‐2‐yl)ethane, and bbp = 1, 3‐bis(benzoimidazol‐2‐yl)propane) were synthesized under hydrothermal conditions, and characterized by elemental analyses, IR spectroscopy, single‐crystal X‐ray diffraction, and thermogravimetric analyses. Compound 1 is a 1D chain, whereas 2 is a (3, 3)‐connected 2D network with (6³) topology. These two 1D and 2D complexes are further connected by hydrogen bonds to form the 3D supramolecular architectures. The electrochemical lithium‐ion storage properties of the as‐made Co₃O₄ by calcination of 1 are investigated in detail.     

Influence of Flexible Bis(benzimidazole) Derivatives on the Self‐assembly of Three Mixed Ligands Silver(I) Coordination Polymers

Three silver(I) coordination polymers namely, [Ag₄(L1)₂(1, 4‐ndc)₂]_n ( 1 ) {[Ag(L2)] · (1, 4‐Hndc) · H₂O}_n ( 2 ), and {[Ag(L3)(H₂O)] · (1, 4‐Hndc)}_n ( 3 ) [L1 = 1, 3‐bis(benzimidazol‐1‐ylmethyl)benzene, 1, 4‐H₂ndc = 1, 4‐naphthalenedicarboxylic acid, L2 = 1, 3‐bis(5, 6‐dimethylbenzimidazole‐1‐ylmethyl)benzene, L3 = 1, 4‐bis(5, 6‐dimethylbenzimidazole)butane], were hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction analysis, elemental analysis, IR spectroscopy, thermogravimetric and XRPD analysis. Complex 1 displays a 1D tube‐like chain, which is packed into a 3D supramolecular network by π–π stacking interactions. Complex 2 features an infinite 1D linear chain. Complex 3 contains a 1D wave‐like chain, which is extended into a 3D supramolecular network through O–H ··· O hydrogen bonding interactions. Moreover, these coordination polymers exhibit catalytic properties for degradation of methyl orange in Fenton‐like processes.     

Two Unusual Two‐dimensional (4,4) Network Cadmium Coordination Polymers Based on Flexible Bis(triazole) and Rigid Benzenedicarboxylate Co‐ligands

Two cadmium(II) coordination polymers {[Cd(btp)(NO₂‐1,3‐bdc)(H₂O)]·H₂O}_n ( 1 ) and {[Cd(btp)(1,2‐bdc)(H₂O)]·H₂O}_n ( 2 ) were synthesized by the reaction of 1,3‐bis(1,2,4‐triazol‐1‐yl)propane (btp), 5‐nitroisophthalate (NO₂‐1,3‐bdc), and 1,2‐benzenedicarboxylate (1,2‐bdc). 1 consists of undulated 2D (4,4) networks. Two identical undulated layers are parallel stacking to give a (2D→2D) polythreaded 2D network. A 3D supramolecular architectute is constructed through the hydrogen bond interactions. 2 has an unusual 2D (4,4) network with a thickness of ca. 10 Å. The btp ligands exhibit the anti‐gauche conformation in 1 and the anti‐anti conformation in 2 . The flexible btp ligand exhibits the key role in the assembly of the topologies of 1 and 2 . The luminescence and thermal stability were investigated.     

Syntheses,Structures, and Luminescence of Metal(II) Coordination Polymers based on Flexible 1,1′‐(1,4‐Butanediyl)bis(imidazole) and Tetrachlorobenzene‐1,4‐dicarboxylate Ligands

The coordination polymers, {[Co(bbim)₂(H₂O)₂](tcbdc) · 2H₂O}_n ( 1 ), {[Ni(tcbdc)(bbim)(H₂O)₂] · 2DMF}_n ( 2 ), and {[Cu₂(tcbdc)₂(bbim)₄] · 4H₂O}_n ( 3 ) [bbim = 1,1′‐(1,4‐butanediyl)bis(imidazole) and tcbdc^2– = tetrachlorobenzene‐1,4‐dicarboxylate] were synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, luminescence, and single‐crystal X‐ray diffraction analysis. Complex 1 has a double‐stranded chain structure through doubly bridged [Co(bbim)₂] units. Complex 2 exhibits two‐dimensional square grid, whereas complex 3 has a three‐dimensional porous network structure with an unprecedented 4⁴ · 6¹¹ topological structure through interpenetrating square grid. The water molecules in complex 3 occupy the vacancy through three kinds of hydrogen bond interactions. Upon excitation at 370 nm, complexes 1 – 3 present solid‐state luminescence at room temperature.     

Divalent Metal 2,5‐Thiophenedicarboxylate Coordination Polymers with the Conformationally Flexible Bis(4‐pyridyl­formyl)homopiperazine Ligand

Divalent metal coordination polymers containing the rigid 2,5‐thiophenedicarboxylate (tdc) ligand and the conformationally flexible dipyridylamide ligand bis(4‐pyridylformyl)homopiperazine (bpfh) show different layer topologies and chirality. As determined by single‐crystal X‐ray diffraction, {[Cd(tdc)(bpfh)(H₂O)] · 3H₂O}_n ( 1 ) shows a twofold parallel interpenetrated centrosymmetric (4,4) layered grid structure. {[Zn(tdc)(bpfh)] · H₂O}_n ( 2 ) exhibits a similar system of twofold interpenetrated (4,4) grid‐like layers, but in contrast to 1 , it crystallizes in an acentric space group. {[Ni₂(tdc)₂(bpfh)₂(H₂O)] · 2H₂O}_n ( 3 ) possesses {Ni₂(μ‐H₂O)(OCO)₂} dimeric units connected into a doubled layer motif by the full span of the tdc and bpfh ligands. Weak antiferromagnetic coupling is observed within the dimeric units in 3 [g = 2.172(6) and J = –0.79(1) cm^–1]. Compounds 1 and 2 undergo blue‐violet fluorescence upon ultraviolet irradiation; the cadmium derivative 1 shows potential as a sensor for the solution‐phase detection of nitrobenzene although coordination polymer exfoliation likely occurs. Thermal decomposition behavior of the three new phases is also discussed.     

Synthesis,Crystal Structures,and Thermal Analyses of ­Copper(II) and Manganese(II) Mixed‐Ligand Coordination Polymers Constructed from Benzimidazole‐5, 6‐dicarboxylic Acid and N‐Donor Ligands

The coordination polymers, {[Cu(Hbidc)(2, 2′‐bpy)(H₂O)] · 2H₂O}_n ( 1 ) and {[Mn(Hbidc)(2, 2′‐bpy) (H₂O)₂] · 2H₂O}_n ( 2 ) (H₃bidc = benzimidazole‐5, 6‐dicarboxylic acid, 2, 2′‐bpy = 2, 2′‐bipyridine), were synthesized in solution and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), and single‐crystal X‐ray diffraction. Complexes 1 and 2 consist of different 1D chain structures. In both compounds, 2, 2′‐bpy is chelating in a bidentate manner, whereas the Hbidc ligands in complexes 1 and 2 display chelating‐bridging tridentate and bridging bidentate coordination modes. The two complexes are further extended into 3D supramolecular structures through O–H ··· O and N–H ··· O hydrogen bonds. The thermal stabilities of complexes 1 and 2 were studied by thermogravimetric analyses (TGA).     

Hydrothermal Synthesis,Crystal Structures,and Catalytic Properties of Three Coordination Polymers Containing ­Flexible Bis(benzimidazole) and Dicarboxylate Ligands

Three metal‐organic coordination polymers, namely {[Cd(L1)(1,2‐chdc)] · 2H₂O}_n ( 1 ), {[Ni(L2)(1,2‐chdc)] · H₂O}_n ( 2 ), and [Cd(L2)(npht)]_n ( 3 ) [L1 = 1,2‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, L2 = 1,2‐bis(5,6‐dimethylbenzimidazol‐1‐ylmethyl)benzene, 1,2‐H₂chdc = 1,2‐cyclohexanedicarboxylic acid, H₂npht = 3‐nitrophthalic acid] were synthesized under hydrothermal conditions and structurally characterized by single‐crystal X‐ray diffraction methods, IR spectroscopy, TGA, and elemental analysis. In compound 1 , two 1,2‐chdc^2– ligands connect two neighboring Cd atoms to form a dinuclear [Cd₂(1,2‐chdc)₂] subunit, which is further linked by L1 ligands to construct a 1D ladder‐like chain. Compound 2 exhibits a 2D (4,4) coordination network with {4⁴.6²} topology, whilst compound 3 shows a 1D helical chain structure. The fluorescence, UV/Vis diffuse reflection spectra, and catalytic properties of complexes 1 – 3 for the degradation of the congo red azo dye in a Fenton‐like process are investigated.     

Syntheses,Structures, and Catalytic Properties of Three Copper(II) Coordination Polymers Based on 2,3,5,6‐Tetrafluoro‐1,4‐bis(triazole‐ylmethyl)benzene and Benzene Carboxylate Ligands

Three new mixed‐ligand coordination polymers of Cu^II, namely, [Cu(Fbtx)(L1)(H₂O)]_n ( 1 ), [Cu(Fbtx)_0.5(HL2)(H₂O)₂]_n ( 2 ), and {[Cu(Fbtx)_1.5(HL3)(H₂O)] · H₂O}_n ( 3 ) [Fbtx = 2,3,5,6‐tetrafluoro‐1,4‐bis(1,2,4‐triazole‐1‐ylmethyl)benenze, H₂L1 = terephthalic acid, H₃L2 = trimesic acid, NaH₂L3 = 5‐sulfoisophthalic acid monosodium salt], were hydrothermally synthesized and structurally characterized by elemental analysis, IR spectra, and single‐crystal and powder X‐ray diffraction techniques. All the complexes have a two‐dimensional (2D) coordination layer structure. Of these, 1 displays a planar 4⁴‐ sql structure whereas both 2 and 3 are highly undulated 6³‐ hcb nets. Moreover, their thermal stability and catalytic behaviors in the aerobic oxidation of 4‐methoxybenzyl alcohol were also investigated as well. The results indicate that the benzene dicarboxylate ligands have an effective influence on the structures and catalytic properties of the resulting coordination polymers.     

Syntheses,Crystal Structures,and Magnetic Properties of Two Cobalt Coordination Polymers Constructed From 1,3‐Bis(2,4‐dicarboxyphenyl) Benzene and Bis(imidazole) Linkers

Abstract. The 3D cobalt(II) coordination polymers [Co_1.5(HDDB)(1,4‐bib)_1.5(H₂O)]_n ( 1 ), and {[Co₂(DDB)(1,3‐bib)₂(μ₂‐H₂O)] · H₂O}_n ( 2 ) were assembled by mixed‐ligand synthetic strategy [H₄DDB = 1,3‐bis(2,4‐dicarboxyphenyl) benzene, 1,3‐bib = 1,3‐bis(1H‐imidazol‐4‐yl)benzene, and 1,4‐bib = 1,4‐bis(1H‐imidazol‐4‐yl)benzene]. Their structures were determined by single‐crystal X‐ray diffraction analyses and further characterized by elemental analyses (EA), IR spectroscopy, powder X‐ray diffraction (PXRD), and thermogravimetric (TG) analyses. Single X‐ray diffraction analysis reveals that complex 1 is an interestingly 3D (3,3.6)‐connected (6³)₄(6⁵ · 8⁸ · 10²) net, and complex 2 is an unprecedented dinuclear [Co₂(COO)(μ₂‐H₂O)] SBUs based 3D (3,6)‐connected (3 · 6 · 7)(3² · 4³ · 5⁴ · 6³ · 7 · 8²) net. Additionally, the magnetic properties of 2 were investigated.     

Substituent Dependent Dimensionality in Luminescent Zinc Isophthalate Coordination Polymers Containing Bis(3‐pyridylmethyl)piperazine

Divalent zinc coordination polymers containing bis(3‐pyridylmethyl)piperazine (3‐bpmp) and isophthalate ligands have been hydrothermally synthesized and structurally characterized by single‐crystal X‐ray diffraction. {[Zn(ip)(H3‐bpmp)]ClO₄·4H₂O}_n ( 1 , ip = isophthalate) has twofold parallel interpenetrated (4,4) grid cationic coordination polymer nets, with unligated perchlorate ions and intriguing infinite water molecule chains. {[Zn₂(NO₂ip)₃(H₂3‐bpmp)(H₂O)₅]·3H₂O}_n ( 2 , NO₂ip = 5‐nitroisophthalate) exhibits a supramolecular lattice built from 1D chain motifs, revealing a significant dependence of topology on the steric bulk of the dicarboxylate ligand. Luminescent properties for 1 and 2 are also reported.     

Metal Ion‐tuned Complexes based on Benzene‐1, 2, 4, 5‐tetracarboxylic Acid and the Semirigid Ligand 1, 4‐Bis(2‐methylbenzimidazol‐1‐ylmethyl) Benzene

Abstract. Two metal‐organic coordination polymers [Co(bmb)(btc)_0.5]_n( 1 ) and {[Zn(bmb)_0.5(btc)_0.5(H₂O)] · 0.5bmb · H₂O}_n ( 2 ) [H₄btc = benzene‐1, 2, 4, 5‐tetracarboxylic acid, bmb = 1, 4‐bis(2‐methylbenzimidazol‐1‐ylmethyl) benzene] were prepared under hydrothermal conditions. Single‐crystal X‐ray diffraction indicates that both complexes have a 2D framework structure with (4 · 6²) (4² · 6² · 8²) topology. Interestingly, the hydrogen bonds in 2 form a fascinating meso‐helix. The catalytic activity of 1 for oxidative coupling of 2, 6‐dimethylphenol (DMP) and the photoluminescence properties of 2 were investigated. Furthermore, the complexes were investigated by IR spectroscopy and thermogravimetric analysis.     

A novel cobalt(II) coordination polymer with an unusual four‐connected 42.63.8 topology

In the cobalt(II) coordination polymer poly[[(μ₂‐benzene‐1,3‐dicarboxylato){μ₂‐1,1′‐[2,2′‐oxybis(ethane‐2,1‐diyl)]di‐1H‐imidazole}cobalt(II)] monohydrate], {[Co(C₁₀H₁₄N₄O)(C₈H₄O₄)]·H₂O}_n, two crystallographically distinct Co^II cations are four‐coordinated by N₂O₂ donor sets in distorted tetrahedral geometries. The Co^II centers are connected by benzene‐1,3‐dicarboxylate (m‐BDC) anions, giving two types of linear chains, which are further joined via meso‐helical 1,1′‐[2,2′‐oxybis(ethane‐2,1‐diyl)]di‐1H‐imidazole ligands to yield a thick two‐dimensional slab. The compound displays a two‐dimensional four‐connected 4².6³.8 topology, which is unprecedented in coordination polymers.     

Metal Chelates of N‐(2‐pyridylmethyl)iminodiacetate(2‐) Ion (pmda). Part II. Ternary pmda Chelates with M = Co,Cu or Zn and Creatinine as Auxiliary Ligand

The compounds [Cu(pmda)(crea)]·H₂O ( 1 ), [Zn(pmda)(crea)]·H₂O ( 2 ) and [Co(pmda)(crea)(H₂O)]·H₂O ( 3 ) were prepared and characterized by thermal, spectral and X‐ray diffraction methods. In compounds 1 and 2 the M^II coordination is of type 4+1 and approaches to a trigonal bipyramid (71.85 and 86.18 %, respectively) with rather linear N(pmda)‐M^II‐N(crea) trans‐apical angles, but with different longest coordination bond (Cu‐O(pmda) or Zn‐N(apliphatic, pmda), respectively). Both compounds are isotypic and one intra‐molecular interligand N‐H···O interaction reinforces the molecular recogniton crea‐M^II(pmda) chelate. In contrast, the compound 3 exhibits an octahedral coordination, imposed by the 3d⁷ electronic configuration of the cobalt(II) atom, and the crea‐chelate recognition involves the Co‐N(crea) coordination bond and one intramolecular ‘bifurcated’ H‐bonding interaction between one N‐H(crea) bond and one O(pmda) plus the O(aqua) atoms as ‘acceptors’.     

Three AgI,CuI and CdII coordination polymers based on the new asymmetrical ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole: syntheses,characterization and emission properties

The new asymmetrical organic ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole ( L , C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena‐poly[[silver(I)‐μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole] hexafluoridophosphate], {[Ag( L )]PF₆}_n, catena‐poly[[copper(I)‐di‐μ‐iodido‐copper(I)‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)] 1,4‐dioxane monosolvate], {[Cu₂I₂( L )₂]·C₄H₈O₂}_n, and catena‐poly[[[dinitratocopper(II)]‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)]–methanol–water (1/1/0.65)], {[Cd( L )₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one‐dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π–π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.