Cadmium Coordination Research Articles

Luminescent cadmium coordination polymers synthesized from bis(4-pyridylmethyl)piperazine and isophthalic acid derivatives

Hydrothermal reaction of cadmium nitrate, 5-substituted isophthalic acid derivatives, and the long-spanning bis(4-pyridylmethyl)piperazine (4-bpmp) ligand afforded a series of crystalline coordination polymers whose topologies and mode of interpenetration depend critically on the nature of the 5-position substituent. {[Cd(mip)(4-bpmp)(H2O)]·3H2O}n (1, mip=5-methylisophthalate) and {[Cd(nip)(4-bpmp)(H2O)]·3H2O}n (2, nip=5-nitroisophthalate) both display (4,4) grid topologies. {[Cd4(hip)4(H2O)4(4-bpmpH)2](hip)·15H2O}n (3, hip=5-hydroxyisophthalate) also manifests a (4,4) grid topology, but is based on {Cd2O2} and {Cd2(OCO)2} dimeric units. [Cd(meoip)(4-bpmp)]n (4, meoip=5-methoxyisophthalate) shows a (4,4) grid topology based only on {Cd2(OCO)2} dimeric units. {[Cd9(meoip)10(4-bpmpH)2(H2O)]·2H2O}n (5) displays a complex 3D coordination polymer net comprised of trimer-based [Cd6(meoip)6]n layers linked by meoip ligands to trimer-based [Cd3(meoip)3(H2O)(4-bpmpH)2]n layers. {[Cd2(aip)2(4-bpmpH)(H2O)2](NO3)·5H2O}n (6, aip=5-aminoisophthalate) shows 3,4-connected slab motifs with (63)(66) topology. {[Cd2(tbuip)2(4-bpmp)3]·8H2O}n (7, tbuip=5-tert-butylisophthalate) exhibits 5-connected slabs with 4862 topology, that engage in parallel 2D+2D→3D interpenetration. {[Cd3(btc)2(H2O)8(4-bpmp)]·6H2O}n (8, btc=1,3,5-benzenetricarboxylate) displays 1D [Cd3(btc)2(H2O)8]n ribbons pillared by 4-bpmp ligands into 2D (6,3) hexagonal nets. {[Cd2Cl4(4-bpmp)3(H2O)2]·4-bpmp·H2O}n (9), prepared from cadmium chloride, 4-bpmp, and 1,3,5-benzenetricarboxylic acid. This shows 1D neutral {[Cd2Cl4(4-bpmp)3(H2O)2]n ladder motifs that interlock and interpenetrate in a 1D+1D→3D manner. Luminescent behavior in the cadmium complexes is ascribed to intra-ligand molecular orbital transitions. The new phases were also surveyed for the ability to detect nitrobenzene in ethanol suspension.

Cadmium(II) Coordination Polymers of 4-Pyr-poly-2-ene and Carboxylates: Construction, Structure, and Photochemical Double [2 + 2] Cycloaddition and Luminescent Sensing of Nitroaromatics and Mercury(II) Ions

Solvothermal reactions of Cd(NO3)2·4H2O with 4-pyr-poly-2-ene (ppene) in the presence of benzene-1,2-dicarboxylic acid (1,2-H2BDC), benzene-1,3-dicarboxylic acid (1,3-H2BDC), benzene-1,4-dicarboxylic acid (1,4-H2BDC), benzene-1,3,5-tricarboxylic acid (1,3,5-H3BTC), or 4,4′-oxidibenzoic acid (4,4′-H2OBA) afforded five Cd(II) coordination polymers [Cd(ppene)(1,2-BDC)]n (1), [Cd(ppene)(1,3-BDC)]n (2), [{Cd(ppene)(1,4-BDC)}·MeCN]n (3) (Liu et al. Inorg. Chem. Commun. 2015, 58, 1−4), [{Cd(ppene)(1,3,5-HBTC)}·0.5(ppene)]n (4), and [Cd(ppene)(4,4′-OBA)]n (5), respectively. Upon UV light irradiation, 1, 3, and 4 can undergo a double [2 + 2] cycloaddition reaction to yield their corresponding photoproducts including [Cd2(4-tp-3-lad)(1,2-BDC)2]n (1a, 4-tp-3-lad = 2,3,5,6-tetra(pyridin-4-yl)bicyclo[2.2.0]hexane), [{Cd2(4-tp-3-lad)(1,4-BDC)2}·2MeCN]n (3a), and [{Cd2(4-tp-3-lad)(1,3,5-HBTC)2}·(ppene)]n (4a) in a single-crystal-to-single-crystal manner. Compounds 1, 2, 4, 5, 1a, 3a, and 4a have been structurally charac...

Luminescent cadmium(ii) coordination polymers of 1,2,4,5-tetrakis(4-pyridylvinyl)benzene used as efficient multi-responsive sensors for toxic metal ions in water.

Reactions of Cd(NO3)2·4H2O with 1,2,4,5-tetrakis(4-pyridylvinyl)benzene (4-tkpvb) and 5-tert-butylisophthalic acid (5-tert-H2BIPA), 1,3,5-benzenetricarboxylic acid (1,3,5-H3BTC) or 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) under solvothermal conditions afforded three two-dimensional (2D) Cd(ii) coordination polymers [Cd(4-tkpvb)(5-tert-BIPA)]n (1), [{Cd(4-tkpvb)(1,3,5-HBTC)}·0.5DMF]n (2) and [Cd(4-tkpvb)(1,4-NDC)]n (3). Compounds 1-3 were structurally characterized by IR, elemental analysis, powder X-ray diffraction, and single crystal X-ray diffraction. Compounds 1-3 possess unique 2D networks in which 1D double chains [Cd2L2]n (L = 5-tert-BIPA or 1,3,5-HBTC) (1-2) or 1D linear chains [Cd(1,4-NDC)]n (3) are linked by 4-tkpvb ligands. Upon UV light excitation, a 4-tkpvb solution in DMF showed an emission band centered at 446 nm with a shoulder at 475 nm. The addition of Hg2+ ions into the 4-tkpvb solution in DMF remarkably changed its colour from colourless to yellow under natural light, or from blue to grey yellow under UV light, which were clearly visible to the naked eye. Compounds 1-3 suspended in water could emit yellow-green light under UV light irradiation. The representative compound 1 was confirmed to be an uncommon multi-responsive luminescent sensor for Hg2+, CrO42- and Cr2O72- ions in water by the luminescence quenching method. The detection limits for these species were 0.15 μM (Hg2+), 0.08 μM (CrO42-) and 0.12 μM (Cr2O72-), respectively. The luminescence quenching mechanism studies revealed that these quenching processes were involved in either the interaction of Hg2+ with free pyridyl groups in 1 or the overlap between the absorption band of CrO42- or Cr2O72- and the excitation and/or emission bands of 1.

Solvothermal self-assembly of Cd2+ coordination polymers with supramolecular networks involving N-donor ligands and aromatic dicarboxylates: synthesis, crystal structure and photoluminescence studies.

Two cadmium(ii) coordination polymers (CPs) of compositions {[Cd(H2O)4(4-BPDB)][BPDC]}n (CP1) and {[Cd(H2O)(BrIP)(BTTMB)]·4MeOH}n (CP2) have been synthesized by solvothermal methods and characterized by several analytical methods including SXRD (Single Crystal X-ray Diffraction). The structure of CP1 can be described as a 1D cationic chain, {[Cd(H2O)4(4-BPDB)]2+}n and discrete BPDC counter anions. The structure of CP2 revealed an undulated 2D sql net comprising Cd2+ nodes bridged by the ditopic N-donor, BTTMB and dicarboxylate BrIP involved in μ2-η1η1η1η1 coordination. Supramolecular interactions in both CPs generate 3D hydrogen bonded architectures. The solid state fluorescence properties of these d10 metal ion containing CPs have been investigated. Fluorescence emission of CP1 suspended in acetonitrile is observed to be selectively quenched by acetone (LOD = 0.15 mM) over other common laboratory solvents.

Cadmium(ii) coordination polymers based on substituted malonic acid: synthesis, characterization and photoluminescence properties

The influence of the chain length on the topology and luminescence of four new cadmium(ii) R-malonate coordination polymers is analysed herein.

A series of novel cadmium(ii) coordination polymers with photoluminescence and ferroelectric properties based on zwitterionic ligands

Herein, a series of Cd(ii) compounds were obtained by using a zwitterionic ligand (H3LBr3) and an aromatic secondary ligand (H4BTC).

Synthesis, structures, and characterizations of two new cadmium(II) coordination polymers constructed from 3-(1-pyrazol-4-yl)-5-(pyridin-2-yl)-1,2,4-triazole and different carboxylate ligands, "Координационная химия"

Synthesis, structures, and characterizations of two new cadmium(II) coordination polymers constructed from 3-(1-pyrazol-4-yl)-5-(pyridin-2-yl)-1,2,4-triazole and different carboxylate ligands, "Координационная химия"

Two cadmium coordination polymers based on tris(p-carboxyphenyl) phosphane oxide with highly selective sensing of nitrobenzene derivatives and Hg2+ cations

Based on the tris(p-carboxyphenyl)phosphane oxide ligand, two Cd(ii) CPs were obtained which could highly sense nitrobenzene derivatives and Hg2+ cations.

Cadmium(II) coordination polymers constructed from a bis-functionalized ligand 4′-(3-carboxyphenyl)-2,2′:6′,2″-terpyridine: Synthesis, structure and luminescence

Five new cadmium(II) coordination polymers [Cd2(L)2Cl2]n·nH2O (1), [Cd(L)Cl(H2O)]n·n[Cd(HL)Cl2]·nH2O (2), [Cd3(L)(1,4-bdc)2.5]n·4nH2O (3), [Cd2(L)(HL)(1,3,5-btc)]n·2nH2O (4), [Cd2(L)2(SO4)]n·2nH2O (5) (HL=4′-(3-carboxyphenyl)-2,2′:6′,2″-terpyridine, H2(1,4-bdc)=benzene-1,4-dicarboxylic acid, H3(1,3,5-btc)=benzene-1,3,5-tricarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compounds 1 and 2 present a 1D chain structure, and further linked by the π–π interaction to form a 2D layer. Compound 3 features a new (3,3,9)-connected 3D network built up by [Cd3(COO)4] clusters with the point symbol of {3·42}{32·46·59·615·73·8}{43}. Compound 4 exhibits a 2D layer structure with binuclear eight-membered rings, which demonstrates a new 3-nodal (3,3,4)-connected topological network with the point symbol of {52·62·92}{52·6}4. Compound 5 displays an achiral 2D layer based on 1D left- and right-handed helical chains and contains dinuclear [Cd2(SO4)] clusters, which shows a 4-connected sql network with the point symbol of {44·62}. Additionally, the thermal stabilities and luminescent properties of 1–5 were investigated.

A luminescent coordination polymer based on a π-conjugated ligand: Syntheses, structure and luminescent property

A new cadmium coordination polymer [Cd(DPFE)(adip)0.5(NO3)]n (1) has been synthesized hydrothermally from the self-assembly of the Cd2+ ion with a new π-conjugated rigid ligand DPFE and the adipic acid, where DPFE = 2,7-di(pyridin-4-yl)-9H-fluorene and H2adip = adipic acid. The structure of 1 was full characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray diffraction. Structural analysis reveals compound 1 is a dinuclear Cd(II) based two-dimensional (4,4) layer and two kinds of strong intramolecular π-π stacking interactions exist between pyridyl rings and benzene rings. In addition, the thermogravimetric analysis and solid–state luminescent properties have also been investigated.

Assembly of anion-controlled cadmium(II) coordination polymers from the use of 2-acetyl-pyridyl-isonicotinoylhydrazone

Four Cd(II) coordination polymers have been synthesized, utilizing a tetradentate pyridine-based Schiff base ligand, namely 2-acetyl-pyridyl-isonicotinoylhydrazone (HL), and different anions (CH3COO−, N3−, SCN−). The products {[Cd2(L)2(CH3COO)2]·C2H5OH}n (1), {[Cd1.5(L)(CH3COO)(N3)(H2O)]·C2H5OH}n (2), {[Cd(HL)(SCN)2]·CH3OH}n (3) and [Cd3(HL)2(SCN)6]n (4), were characterized with single-crystal X-ray diffraction, IR spectroscopy, and luminescence studies. The ligand in 1 and 2 is singly-deprotonated and coordinates to the cadmium centre in the enolic form (N–NC–O) while in compounds 3 and 4 it coordinates in its neutral keto form (N–NH–CO). The tetradentate ligand in 2 acts as a linker and leads to the formation of a one-dimensional coordination polymer. The CH3COO− in 1 and SCN− in 3 and 4, further act as bridges, forming two-dimensional coordination polymers (1 and 3) and a three-dimensional network (4). Structural diversity is thus induced by the anions, due to the variable steric hindrance they impose as well as differing bridging capacity; metal-organic network formation is also evident via different Van der Waals forces.

Synthesis, Structure, Photoluminescent and Drug Loading and Release Properties of a Novel Cadmium (II) Coordination Polymers Based on Terphenyl–3, 4″, 5–tricarboxylic Acid

A stable three-dimensional coordination complex, {[Cd1.5(tta)(H2O)4.5]·H2O}n (1) (tta = terphenyl—3,4″,5—tricarboxylic acid), was prepared by the solvothermal reaction of Cd(CH3COO)2·2H2O and tta in water, which was characterized by infrared spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction, fluorescence, and thermogravimetric analyses. In the solid state of this compound, the Cd (II) center displayed a distorted trigonal bipyramid coordination sphere consisting of two oxygen atoms from two different carboxyl which were offered by two separate tta ligands and three oxygen atoms from three water molecules. The one-dimensional linear (1D) structure and two-dimensional plane were formed by Cd-O coordination bond while the 3D supramolecular reticular structure was formed by hydrogen-bond interactions. And there are large rectangular holes whose size are 13.30 × 13.31 A along crystallographic axis a. The drug loading content (DLC) of 1 was 0.203 g (Ibu)/g (compound) and the release was desirable.

Two 2-dimensional cadmium(II) coordination polymers with 3-amino-5-methylthio-1,2,4-triazolate ligand

Reactions of cadmium(II) salts with 3-amino-5-methylthio-1H-1,2,4-triazole (Hamstz) afforded two cadmium(II) coordination polymers, [Cd2(amstz)2Cl2]n (1) and [Cd2(amstz)2(NO3)2]n (2). Compounds 1 and 2 feature 2-D layered structures based on the dinuclear [Cd2(amstz)2] subunits. The cadmium coordination polyhedra are tetrahedral and tetragonal pyramidal in 1 and 2, respectively, due to the presence of different coordinated anions, Cl− and NO3−. Compounds 1 and 2 exhibit photoluminescence emission with maxima at 620 and 621 nm upon excitation at 470 and 472 nm, respectively, which can be attributed to the ligand-to-metal charge transfer emssion.

Two cadmium compounds with adenine and carboxylate ligands: syntheses, structures and photoluminescence

Two cadmium(II) coordination compounds, [Cd3(CH3CO2)4(ad)2(CH3CN)2]n (1) and [Cd3(5-SIP)2(H-ad)2(H2O)6]n (2) (H-ad = adenine and 5-SIP = 5-sulfoisophthalate), were synthesized and characterized. Compound 1 features a two-dimensional (2-D) layered structure based on linear trinuclear [Cd3(CH3CO2)4] units bridged by monoanionic adenine ligands. In 2, the 5-SIP3− ligands link Cd(II) ions to form a one-dimensional (1-D) ladder, which is further linked by neutral adenine ligands to give a 2-D layered structure. In both structures, the carboxylate ligands link Cd(II) ions to form low-dimensional structures, which are further connected by adenine ligands to give high-dimensional structures. Compounds 1 and 2 exhibit emissions centered at 382 and 416 nm, respectively, which can be attributed to the ligand centered π–π* transition.

Two cadmium coordination polymers with bridging acetate and phenyl-enedi-amine ligands that exhibit two-dimensional layered structures.

Poly[tetra-μ2-acetato-κ8O:O'-bis-(μ2-benzene-1,2-di-amine-κ2N:N')dicadmium], [Cd2(CH3COO)4(C6H8N2)2] n , (I), and poly[[(μ2-acetato-κ2O:O')(acetato-κ2O,O')(μ2-benzene-1,3-di-amine-κ2N:N')cadmium] hemihydrate], {[Cd(CH3COO)2(C6H8N2)]·0.5H2O} n , (II), have two-dimensional polymeric structures in which monomeric units are joined by bridging acetate and benzenedi-amine ligands. Each of the CdII ions has an O4N2 coordination environment. The coordination geometries of the symmetry-independent CdII ions are distorted octa-hedral and distorted trigonal anti-prismatic in (I) and distorted anti-prismatic in (II). Both compounds exhibit an intra-layer hydrogen-bonding network. In addition, the water of hydration in (II) is involved in inter-layer hydrogen bonding.

A cadmium(II) coordination polymer formed from a third generation tetratopic tris(pyrazolyl)methane ligand.

The reaction of a third generation tetratopic tris(pyrazolyl)methane ligand, namely 1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene {1,2,4,5-C6H2[CH2OCH2C(pz)3]4, L4}, and [Cd2(thf)5](BF4)4 (thf is tetrahydrofuran) produces the coordination polymer catena-poly[[[bis[acetonitrilecadmium(II)]-μ4-1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene] tetrakis(tetrafluoroborate)]-diethyl ether-acetonitrile (1/2/2)], {[Cd2(CH3CN)2(C54H54N24O4)](BF4)4·2C4H10O·2CH3CN}n. The CdII center is coordinated in a κ3-fashion by one tris(pyrazolyl)methane group and in a κ2-κ0 fashion by another, while the sixth coordination site on the CdII cation is occupied by an acetonitrile molecule. This bonding mode of the ligand generates an infinite one-dimensional structure built upon 32-atom metallomacrocycles connected by the C6H2 spacer. This compound is isostructural with the silver(I) analogue of this ligand, i.e. {[Ag2(L4)](BF4)2·4CH3CN}n, thus showing the tendency of this system to form metal-based macrocyclic architectures.

Synthesis, structural diversity and luminescent properties of cadmium(II) coordination assemblies with 2-(2-aminophenyl)-1H-benzimidazole and pseudohalide ions

A systematic investigation of Cd(II)–(apbim)–X systems (apbim=2-(2-aminophenyl)-1H-benzimidazole and X=N3–,SCN– and N(NC)2–) was conducted, and the following cadmium(II) coordination compounds [Cd(N3)2(apbim)]n•nMeOH (1), [Cd(SCN)2(apbim)]n•nMeOH (2), [Cd(dca)(apbim)2]n•n(NO3) (3), [Cd(SCN)2(apbim)2] (4) and [Cd(dca)2(apbim)2]•H2O (5) were successfully synthesized and characterized by single-crystal diffraction, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) analysis and IR spectroscopy. The luminescent properties of 2-(2-aminophenyl)-1H-benzimidazole and cadmium(II) coordination compounds were studied in solution (4 and 5) and solid state (1–5). The studies revealed that the solid state architecture and solid state photoluminescent properties of the Cd(II)–apbim–X systems (X=N3, NCS– and dca–) are strongly influenced by intermolecular interactions.

Two new hexacoordinated coordination polymers of cadmium(II) containing bridging units only: Syntheses, structures and molecular properties

The syntheses, characterizations and structures of a neutral 2D coordination polymer [Cd(bnzd)(NCS)2]n (1) and a polycationic 3D coordination polymer isolated as perchlorate salt [Cd(bnzd)3]n(ClO4)2n (2) (bnzd = benzidine) are described. X-ray structural analyses reveal that each hexacoordinated cadmium(II) center in 1 adopts a distorted octahedral geometry with a CdN4 S 2 chromophore bound by two N atoms of two different bnzd units and two N and two S atoms of symmetric doubly bridged end-to-end NCS − units extended in a 2D sheet. Six N atoms of six different bridged bnzd units are bonded to each cadmium(II) in 2 in a non-ended fashion affording a 3D network structure. In the crystalline state, each 2D sheet structure in 1 is further stabilized by π⋯π interaction which in turn affords a 3D network structure through multiple intermolecular N-H ⋯S hydrogen bonds. On the other hand, the 3D network structure in 2 is stabilized by weak intermolecular N-H ⋯O hydrogen bonds and C-H ⋯π interactions. Bnzd, 1 and 2 display intraligand 1(π- π*) fluorescence in DMF solution at room temperature. Two cadmium(II) coordination polymers of benzidine with or without thiocyanate afford varied metal-organic frameworks (MOFs) through multiple weak non-covalent forces and are good luminous materials.

Crystal structures and luminescence properties of a one-dimensional cadmium coordination polymer derived from a flexible bis(imidazole) ligand

A new Cd(II) coordination polymer, namely [Cd(pbmb)(mip)]n (pbmb = 1,1′-(1,3-propane)bis-(2-methylbenzimidazole), H2mip = 5-methylisophthalic acid), is hydrothermally synthesized and characterized by elemental analyses, infrared spectroscopy and single crystal X-ray diffraction analyses. It crystallizes in the triclinic space group \(P\overline 1 \), a = 0.2883(11), b = 11.3409(12), c = 13.2519(14) A, α = 69.6950(10)°, β = 73.5850(10)°, γ = 63.8100(10)°, V = 1285.8(2) A3, Z = 2, C28H28CdN4O5, M r = 612.94, D c = = 1.583 g/cm3, μ = 0.896 mm–1. In the complex, adjacent dinuclear units [Cd2(pbmb)2] are bridged by mip2– ligands in the μ2-η2, η1 coordination modes to construct 1D ladder-like chains which are additionally assembled into a 2D supramolecular network via C–H∙∙∙π interactions. Moreover, the luminescence properties of the complex are described.

Temperature-induced single-crystal-to-single-crystal polymorph transformation in cadmium(II) trimer with pyridine-4-propanamide

Single-crystal-to-single-crystal (SCSC) transformations have been established as an interesting solid state phenomenon and have gained some interest, as the transformed structure can be also determined, providing insight into the possible mechanism of transformation. SCSC transformations may be induced by external stimuli like heat, light or sorption/desorption of guest/solvent molecules and usually occur in metal-organic frameworks (MOFs). The studies of SCSC polymorph transformations of metal-organic compounds are scarce, but they start to gain attention. The molecular structure of cadmium(II) coordination trimer with pyridine-4-propanamide (4-Propy), [Cd3 Cl4(H2O)4 (4-Propy)6 ](CH3 CH2 COO)2 (1), consists of three cadmium(II) ions bridged with chloride ions ; each is coordinated by two N-monodentate 4-propy ligands. Two water molecules are bound to the terminal cadmium(II) ions of the trimer, preventing further polymerization of the trimer units. High-temperature polymorph (A) of 1 crystallized in triclinic system (P-1 space group) at room temperature. SCSC transformation to low- temperature polymorph (B) of 1 occurred by cooling a single crystal to 150 K on a diffractometer. Polymorph B crystallized in monoclinic system (P2 1 /n space group). In A, trimer units are linked via propanoate ions by N–H···O interactions, forming a 1D chain along the [0 1 1] direction. However, in B, similar 1D chains are assembled into a 2D network in the plane (0 1 0) due to the additional N–H···Cl interactions, present only in B. Therefore, lowering temperature enables the assembly of the 1D chains of A into 2D network of B by introducing different type of interaction (N–H···Cl). It seems that the transformation of A into B is possible due to slight change of the molecules’ orientation in the structure of A, enabling the formation of N–H···Cl interactions in the same crystal, without a collapse of the crystal structure. This SCSC polymorph transformation was also studied by PXRD and DSC. The Hirshfeld surface analysis was performed to identify the interactions present in A and B, revealing differences between the two polymorphs.