Syntheses and luminescence of four supramolecular coordination complexes with flexible ligand

Four d ¹⁰-based complexes with chemical formulae {[Zn(L¹)₂(H₂O)₂(4,4′-Bipy)₂] (I), {[Zn₂(L¹)₄(Mi)] · 4H₂O} (II), {[Zn(L¹)₂(Phen)] · H₂O} (III) {[Cd(L¹)₂(Phen)] · 2H₂O} (IV) (HL¹ = p-hydroxy phenylacetic acid, 4,4′-Bipy = 4,4′-bipyridine, Phen = 1,10-phenanthroline, Mi = 1,4-bis(imidazol-1-yl)butane) have been synthesized and structurally characterized by single crystal X-ray diffraction (CIF files CCDC nos. 1047119 (I), 1047120 (II), 1047121 (III), 1047122 (IV)). The significant effect of assistant ligands and metal ions on assembly of I?IV has been demonstrated, which leads to the formation of distinct crystalline products. Complexes I?IV show various coordination motifs with different existing forms and coordination modes of the organic ligands. Furthermore, extend supramolecular networks are connected by secondary interactions such as hydrogen-bonding and aromatic stacking. The thermal stability and luminescent properties of the compounds were discussed in detail.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

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.     

A series of new oxo-vanadium(IV) complexes with octahedral coordinated vanadium centers

A series of new oxo-vanadium(IV) complexes, [VOCl0.69(OH)0.31 (2,2′-bipy)2]Cl·2H2O (1, 2,2′-bipy?=?2,2′-bipyridine) [(VO)₂Cl₄(4,4'-bipy)₃ (H₂O)₂] (2, 4,4'-bipy?=?4,4'-bipyridine), [VO(ida)(H₂O)]_n (3, H₂ida?=?iminodiacetic acid), and [(VO)₂(oa)₄]_n·4n(H₃O)·n(H₂O) (4, H₂oa?=?oxalic acid), have been synthesized and structurally characterized. 1 contains a [VOCl_0.69(OH)_0.31(2,2′-bipy)₂]⁺ cation, Cl ^– anion and two free H₂O molecules. 2 exhibits a binuclear centrosymmetric moiety built up from two [VOCl₂(4,4'-bipy)(H₂O)] units and one bridging 4,4'-bipy ligand, which provides a rare example of a 4,4'-bipy molecule acting as monodentate ligand. 3 displays a neutral chain [VO(ida)(H₂O)]_n constructed by the linkages of [VO(H₂O)]²⁺ units and ida^2? bridging ligands, while 4 offers the only example of three kinds of oa^2- ligands coexisting within the same anionic chain [(VO)₂(oa)₄^4-]_n. Their spectroscopic properties were investigated, and the magnetic susceptibility of 4 shows antiferromagnetic behavior.     

Tuning topological and dimensional versatility from 1D to 3D of Zn/Cd luminescent biphenyl-3,5-dicarboxylate coordination polymers by ancillary ligand

The present study reports application of biphenyl-3,5-dicarboxylic acid (H₂L) as a versatile building block for synthesis of d¹⁰ metal coordination polymers (CPs). Five Cd(II) and Zn(II)-containing CPs based on N,N-donor ancillary ligands, [Cd₂(μ₃-L)₂(μ₂-4,4′-tmbpy)(MeOH)]_∞ (1), [Cd(μ₂-L)(2,2′-bpy)(H₂O)]_∞·n(MeOH) (2), [Cd(μ₂-L)(dipt)]_∞ (3), [Cd(μ₃-L)(phen)]_∞·nH₂O (4), and [Zn(μ₂-L)(μ₂-4,4′-tmbpy)]_∞·nH₂O (5) {4,4′-tmbpy = 4,4′-trimethylenedipyridine, 2,2′-bpy = 2,2′-bipyridine, dipt = 2,9-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline} have been prepared under solvothermal conditions. 1–5 have been characterized by single crystal X-ray diffraction, elemental analysis, infrared (IR) spectra, and powder X-ray diffraction (PXRD). Complex 1 exhibits a three-dimensional (3-D) framework with a rare fsc-3,4-I41/amd topology. Complexes 2–4 show one-dimensional (1-D) structures. Complex 5 features a two-dimensional (2-D) layer structure with a sql topology. The structural and topological diversity of 1–5 are mainly attributed to the effect of the N,N-donor ancillary ligand. Solid-state luminescent properties and thermal stabilities of the obtained products have been investigated.     

Two naphthoate-based lead(II) complexes with different limited-nuclear motifs: Syntheses,crystal structures,and fluorescent properties

Two new naphthoate-based lead(II) complexes, [Pb(NA)₂(2,2’-Bipy)] (I) and [Pb₂(NA)₄(4,4’- Bipy)] (II) (NA–= 1-naphthoate, 2,2’-Bipy = 2,2’-bipyridine, and 4,4’-Bipy = 4,4’-bipyridine) (CIF files CCDC nos. 664900 (I), 664899 (II)) have been hydrothermally synthesized by varying the N-heterocyclic coligands. Structural analyses reveal that the two complexes possess different limited-nuclear motifs, the former one owns mononuclear unit and the last complex exhibits centrosymmetric binuclear motif bridged by 4,4’-Bipy connector. The coordination numbers of Pb(II) metal centers in I and II are four and five, respectively. The NA^– anions in both complexes show the same binding modes, it is obvious that the bipyridyl coligands in the present mixed-ligands system are responsible for the dissociation or dimerization of mononuclear structural units and the binding numbers of the metal ion. In both complexes, the 6s lone pair of electrons of Pb²⁺ has a stereochemistry activity resulting the distribution of the Pb–O and Pb–N bonds in a hemisphere. Furthermore, both of the two compounds are linked to 2D network by intermolecular C–H···O hydrogen bonding and π···π stacking interactions, exhibiting strong fluorescent emissions resulting from the NA^?-based intraligand charge transfer at room temperature, which can be hopefully used as fluorescent materials.     

Hydrothermal synthesis, crystal structure of two new coordination polymer {[Ni2(Imazameth)2(4,4′-Bipy)] · (ClO4) · CH2OH · H2O} n and [Cu2(PDA)1.5(2,2-Bipy)2](H2O)5(NO3)

Two new metal-organic coordination polymers framework formulated as [Cu₂(PDA)_1.5(2,2′-Bipy)₂](H₂O)₅(NO₃) (I) and {[Ni₂(Imazameth)₂(4,4′-Bipy)] · (ClO₄) · CH₂OH · H₂O _n (II), where H₂PDA = 1,4-phenylenediacetic acid, 2,2′-Bipy = 2,2′-bipyridine, Imazameth = (+/?)2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-5-methyl-3-pyridinecarboxylic acid, 4,4′-Bipy = 4,4′-bipyridine, have been prepared and characterized by spectral method (IR), elemental analysis and single crystal X-ray diffraction techniques. Complex I consists of one-dimensional ladder-like chains featuring binuclear unit in which the two Cu²⁺ ions have different coordination geometry: one is five-coordinated, the other is six-coordinated. Complex II is a new two-dimensional copper complex with the peculiarity of having the 4,4′-Bipy ligand and Imazameth ligand acting as bridge to form planar network polymer. Both I and II exist abundant hydrogen bonds. It is result in the formation of a supermolecular crystal, in which they seem to be effective in the stabilization of the structure.     

Cadmium(II) complexes with monoiodo- and dibromodipyrromethenes: synthesis,molecular structure,spectral-luminescent properties,and stability in solutions

Cadmium(II) chelates with 4-iodo-, 5,5´-, and 4,4´-dibromo-2,2´-dipyrromethenes (HL¹, HL², and HL³, respectively) with the composition of [CdL₂] were synthesized. The influence of structural features of their molecules and properties of the medium on the characteristics of absorption and fluorescence spectra, and also on the thermodynamic stability constants in solutions was evaluated. The results of quantum chemical calculations revealed that the additional coordination interactions between the bromine atoms at the α-positions of dipyrromethene ligands and the complexing atom are possible in the molecular structure of α,α´- dibromosubstituted dipyrromethenate [Cd(L²)₂] in contrast with β-halogenated analogues [Cd(L¹)₂] and [Cd(L³)₂].     

Synthesis and luminescent properties of the complexes EuL(<Emphasis Type="Italic">i</Emphasis>-Bu<Subscript>2</Subscript>PS<Subscript>2</Subscript>)<Subscript>2</Subscript>(NO<Subscript>3</Subscript>) (L = Phen, 2,2′-Bipy, 4,4′-Bipy)

The mixed ligand coordination compounds EuL(i-Bu₂PS₂)₂(NO₃) (L = Phen, 2,2′-Bipy, 4,4′-Bipy) are synthesized. On the basis of X-ray analysis and IR spectra their structures are elucidated. The complexes containing Phen or 2,2′-Bipy are found to possess photoluminescent property.     

Tweaking the affinity of aryl‐substituted diazosalicylato‐ and pyridine ligands towards Zn (II) and its neighbors in the periodic system of the elements,Cu (II) and Cd (II), and their antimicrobial activity

A series of six new Zn (II) compounds, viz., [Zn(HL^ASA)₂(Py)₂] ( 1 ), [Zn(HL^MASA)₂(Py)₂] ( 2 ), [Zn(HL^MASA)₂(4‐MePy)₂] ( 3 ), [Zn(HL^CASA)₂(4‐MePy)₂] ( 4 ), [Zn(HL^BASA)₂(Py)₂] ( 5 ), [Zn(HL^BASA)₂(4‐MePy)₂] ( 6 ) and representative Cu (II) and Cd (II) complexes, viz., [Cu(HL^ASA)₂(Py)₂(H₂O)] ( 7 ) and [Cd(HL^BASA)₂(Py)₃] ( 8 ) [(HL^XASA)^? = para‐substituted 5‐[(E)‐2‐(aryl)‐1‐diazenyl]‐2‐hydroxybenzoate with X = H (ASA), Me (MASA), Cl (CASA) or Br (BASA); Py = pyridine; 4‐MePy = 4‐methylpyridine] have been synthesized and characterized by spectroscopic techniques and single‐crystal X‐ray diffraction analysis. The structural characterization of the compounds revealed distorted tetrahedral ( 1 – 6 ), square‐pyramidal ( 7 ) and pentagonal‐bipyramidal ( 8 ) coordination geometries around the metal atom, in which the aryl‐substituted diazosalicylate ligands are coordinated only through the oxygen atoms of carboxylate groups, either in an anisobidentate or isobidentate mode; meanwhile, the 2‐hydroxy groups of the monoanionic ligand (HL^XASA)^? are involved only in intramolecular O‐H···O hydrogen bonds with the carboxylate function. In the crystal structures of 1 – 8 , the complex molecules are assembled by π‐stacking interactions giving mostly infinite 1D strands. The intermolecular binding in the solid state structures is accomplished by diverse additional non‐covalent contacts including C‐H···O, C‐H···N, C‐H···π, C‐H···Br, O···Br, Br···π and van der Waals contacts. Although the primary and secondary ligands in the Zn (II) complex series 1 – 6 carry different substituents at the periphery (X = H, Me, Cl, Br for (HL^XASA)^? and R = H, Me for 4‐Py‐R), five of the crystal structures were isostructural. Additionally, the antimicrobial activity of the pro‐ligands H₂L^XASA and their Zn (II), Cu (II) and Cd (II) compounds were studied in a comparative manner, showing high sensitivity (IZD ≥ 20) against Bacillus subtilis.     

Structure Modulation in Four New Coordination Polymers by In Situ Ligands Synthesis of Anthracene Derivatives and Various Auxiliary N-donor Ligands

Four novel coordination polymers, [Zn(HL¹)₂(phen)₂]·2CH₃OH·2H₂O (1), [ZnCl(HL¹)(4,4′-bipy)_0.5] _n (2), [Cd(HL¹)(L²)_0.5(2,2′-bipy)₂]·3H₂O (3), [Zn(L³)_0.5(N₃)_1.5(phen)] _n (4) (H₂L¹ = 9-(1H-tetrazole-5-yl)-10-carboxyl anthracene, H₂L² = 9,10-di-(1H-tetrazole-5-yl) anthracene, HL³ = 9-(1H-tetrazole-5-yl)-10-cyan anthracene, 1,10-phen = 1,10-phenanthroline, 4,4′-bipy = 4,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine), have been constructed by in situ ligands synthesis system. The formation of tetrazole-based ligands H₂L¹, H₂L² and H₂L³ involves the in situ Sharpless [2 + 3] cycloaddition reaction between 9,10-dicyanoanthracene (DCA) and NaN₃ in the presence of Zn²⁺/Cd²⁺ ions as Lewis-acid catalysts under hydro/solvothermal conditions. At the same time, there is also another in situ carboxyl ligand synthesis reaction by hydrolysis from nitrile in compounds 1 and 2. The four compounds have been characterized by elemental analysis, IR and single-crystal X-ray diffraction analysis. Compound 1 exhibits a butterfly-shaped mononuclear structure. Compound 2 represents a 2D framework constructed by six-membered {Zn₆} rings as secondary building units (SBUs). Compound 3 presents a dinuclear {Cd₂} structure with two butterflies “flying side by side” fashion. While compound 4 displays a 1D chain structure based on a dinuclear {Zn₂} SBUs. Moreover, the luminescence properties of 1–4 have been also investigated.     

Syntheses,structures of Mn(II), Ni(II), Cu(II) and Zn(II) coordination complexes based on 3,4,5-trifluorobenzeneseleninic acid and N-donor ligands

Abstract

Five new coordination complexes [Mn^II (L₁)₂(4,4′-bpy)]_n (1), [Ni^II (L₁)₂(4,4′-bpy)]_n (2), [Zn^II (L₁)₂(4,4′-bpy)]_n (3), [Cu^II (L₁)₂(phen)₂]Cl₂ (4) and [Cu^II ₂(L₁)₂(2,2′-bpy)₂]Cl₂ (5) (HL₁?=?3,4,5-trifluorobenzeneseleninic acid, 4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline), have been synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), elemental analysis and IR spectroscopy. Complexes 1–3 display similar layers structures. In 1–3, the adjacent layers are further connected through π···π interactions to form three-dimensional supramolecular structures. Complexes 4 and 5 show a dimer containing an eight-membered ring. The dimer extends into three-dimensional supramolecular structures through π···π interactions, C–H···F and C–H···Cl interactions.     

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.     

Synthesis,characterization, DNA-binding,and antioxidant activities of four copper(II) complexes containing N-(3-hydroxybenzyl)-amino amide ligands

Four new substituted amino acid ligands, N-(3-hydroxybenzyl)-glycine acid (HL₁), N-(3-hydroxybenzyl)-alanine acid (HL₂), N-(3-hydroxybenzyl)-phenylalanine acid (HL₃), and N-(3-hydroxybenzyl)-leucine acid (HL₄), were synthesized and characterized on the basis of ¹H NMR, IR, ESI-MS, and elemental analyses. The crystal structures of their copper(II) complexes [Cu(L₁)₂]·2H₂O (1), [Cu(L₂)₂(H₂O)] (2), [Cu(L₃)₂(CH₃OH)] (3), and [Cu(L₄)₂(H₂O)]·H₂O (4) were determined by X-ray diffraction analysis. The ligands coordinate with copper(II) through secondary amine and carboxylate in all complexes. In 2, 3, and 4, additional water or methanol coordinates, completing a distorted tetragonal pyramidal coordination geometry around copper. Fluorescence titration spectra, electronic absorption titration spectra, and EB displacement indicate that all the complexes bind to CT-DNA. Intrinsic binding constants of the copper(II) complexes with CT-DNA are 1.32?×?10^6?M^?1, 4.32?×?10^5?M^?1, 5.00?×?10^5?M^?1, and 5.70?×?10^4?M^?1 for 1, 2, 3, and 4, respectively. Antioxidant activities of the compounds have been investigated by spectrophotometric measurements. The results show that the Cu(II) complexes have similar superoxide dismutase activity to that of native Cu, Zn-SOD.     

Self-assembly of four new extended architectures based on reduced polyoxometalate clusters and cadmium complexes

Four new [P₄Mo₆] cluster-based extended structures containing cadmium complexes, [Cd₃(4,4′-Hbpy)₂(4,4′-bpy)₂(H₂O)₈][Cd(H₂PO₄)₂(HPO₄)₄(PO₄)₂(MoO₂)₁₂(OH)₆]·7H₂O 1, (4,4′-Hbpy)₂[Cd(4,4′-bpy)₃(H₂O)₃][Cd(4,4′-bpy)(H₂O)]₂[Cd(H₂PO₄)₂(HPO₄)₄ (PO₄)₂(MoO₂)₁₂(OH)₆]·H₂O 2, [Cd₄(phen)₂(H₂O)₄][Cd(phen)(H₂O)]₂[Cd(HPO₄)₄ (HPO₄)₄(MoO₂)₁₂(OH)₆]·5H₂O 3 and [Cd₄(2,2′-bpy)₂(H₂O)₄][Cd(2,2′-bpy)(H₂O)]₂ [Cd(HPO₄)₄(HPO₄)₄(MoO₂)₁₂(OH)₆]·3H₂O 4 (4,4′-bpy=4,4′-bpyridine, phen=1,10-phenanthroline, 2,2′-bpy=2,2′-bpyridine), have been synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The structure of compound 1 is constructed from the Cd[P₄Mo₆]₂ dimers linked by [Cd₃(4,4′-Hbpy)₂(4,4′-bpy)₂(H₂O)₈] subunits to generate a plane layer. Compound 2 consists of the positive 2D sheets that constructed from Cd[P₄Mo₆]₂ dimers linked by [Cd(4,4′-bpy)(H₂O)] complexes, then the 2D sheets are further linked up together to form a 3D supramolecular framework via extensive hydrogen-bonding interactions among the [P₄Mo₆] clusters, free 4,4′-bpy molecules, dissociated [Cd(4,4′-bpy)₃(H₂O)₃]²⁺ complexes and water molecules. Compounds 3 and 4 show new 2D layered structure, with Cd[P₄Mo₆]₂ building blocks connected by tetra-nuclear [Cd₄{(phen)₂/(2,2′-bpy)₂}(H₂O)₄] clusters and [Cd(phen/2,2′-bpy)(H₂O)] complexes. The fluorescent activities of compounds 3 and 4 are reported.     

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.     

Four divalent transition metal carboxyarylphosphonate compounds: Hydrothermal synthesis, structural chemistry and generalized 2D FTIR correlation spectroscopy studies

Four divalent transition metal carboxyarylphosphonates, [Ni(4,4′-bipy)H₂L¹(HL¹)₂(H₂O)₂]·2H₂O 1, [Ni₂(4,4′-bipy)(L²)(OH)(H₂O)₂]·3H₂O 2, Mn(phen)₂(H₂L¹)₂3 and Mn(phen)(HL²) 4 (H₃L¹=p-H₂O₃PCH₂-C₆H₄-COOH, H₃L²=m-H₂O₃PCH₂-C₆H₄-COOH, 4,4′-bipy=4,4′-bipyridine, phen=1,10-phenanthroline) were synthesized under hydrothermal conditions. 1 features 1D linear chains built from Ni(II) ions bridging 4,4′-bipy. In 2, neighboring Ni₄ cluster units are connected by pairs of H₃L² ligands to form 1D double-crankshaft chains, which are interconnected by pairs of 4,4′-bipy into 2D sheets. 3 exhibits 2D supramolecular layers via the R₂²(8) ringed hydrogen bonding units. 4 has 1D ladderlike chains, in which the 4-membered rings are cross-linked by the organic moieties of the H₃L² ligands. Additionally, 2D FTIR correlation analysis is applied with thermal and magnetic perturbation to clarify the structural changes of functional groups from H₃L¹ and H₃L² ligands in the compounds more efficiently.     

Synthesis and molecular characterization of the coordination polymer [Pb(2,2′-Bipy)(NO3)2(H2O)] n

A new coordination polymer [Pb(2,2′-Bipy)(NO₃)₂(H₂O)] _n has been successfully synthesized and characterized (where 2,2′-Bipy = 2,2′-bipyridine). The crystal structure of the polymer was determined by single-crystal X-ray diffraction, crystallizing in the monoclinic crystal system, space group P2₁/n with unit cell parameters: a = 7.1673(5), b = 9.8706(6), c = 19.1825(12) Å; β = 90.0780(10)°; V = 1357.08(15) ų, and Z = 16. The Pb atom was six-coordinated with N(1) and N(2) from 2,2′-Bipy, O(2), O(3), and O(6) in nitrate; O(1) from coordinated water, forming a slightly distorted octahedral geometry. The structure units aggregate together to give birth to the infinite 1D chains via bridged nitrate, and 2D networks and three-dimensional frameworks were obtained through hydrogen bonding and π-π-stacking interaction among aromatic rings, respectively.     

Synthesis of mixed-ligand managanese(II) complexes with alkyl xanthate ions and nitrogen-containing heterocycles. Crystal and molecular structure of the [Mn(S2COC3H7−i )2(2,2′-Bipy)] complex

We have synthesized high-spin mixed-ligand Mn²⁺ complexes Mn(S₂COR)₂L where R=i−C₃H₇, i−C₄H₉; [L=1,10-phenanthroline (Phen), 2,2′-bipyridyl (2,2′-Bipy), 4,4′-bipyridyl (4,4′-Bipy)]. As solids, the compounds are stable to oxidation by atmospheric oxygen. An X-ray structural study of the [Mn(S₂COC₃H₇−i)₂(2,2′-Bipy)] complex was carried out. The structure is composed of discrete monomeric molecules. The corrdination polyhedron of the Mn atom is a distorted [4S+2N] octahedron. The molecules are bonded by van der Waals interactions. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 2, pp. 106–111, March–April, 1994. Translated by T. Yudanova     

Mixed‐Ligand Zn‐MOFs for Highly Luminescent Sensing of Nitro Compounds

Three Zn^II metal‐organic frameworks (Zn‐MOFs), [Zn₂(tib)(HL¹)(H₂L¹)_0.5]?2H₂O ( 1 ), [Zn₂(tib)(L²)]?H₂O ( 2 ) and [Zn₃(tib)(L³)₂(H₂O)₆]?2 H₂O ( 3 ), have been prepared by reactions of 1,3,5‐tris(1‐imidazolyl)benzene (tib), and biphenyl‐3,3′,4,4′‐tetracarboxylic acid (H₄L¹), 4,4′‐oxydiphthalic acid (H₄L²), or benzene‐1,3,5‐tricarboxylic acid (H₃L³) with corresponding Zn^II salts, respectively. Single crystal structure analyses reveal that 1 and 2 are constructed by Zn‐centered polyhedra, tib and multidentate tetracarboxylate ligands to form 3‐dimensional frameworks. In contrast, when the tetracarboxylate ligands were replaced by tricarboxylate ligand, layered structure of 3 is produced. These compounds are further characterized by powder X‐ray diffraction, element analyses, thermogravimetric analyses and photoluminescent spectroscopy. The luminescent properties of three Zn‐MOFs dispersed in different solvents have been investigated systematically, demonstrating high sensitivity for the detection of nitro compounds via a fluorescence quenching mechanism.