Tetranuclear Cadmium Research Articles

A d10-Cd Cluster Containing Sandwich-Type Arsenotungstate Exhibiting Fluorescent Recognition of Carcinogenic Dye in Methanol

A d10-Cd cluster containing sandwich-type arsenotungstate [C3H12N2]6[Cd4Cl2(B-α-AsW9O34)2] was synthesized and its structure characterized through elemental analyses, X-ray powder diffraction (XRPD), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and single-crystal X-ray diffraction. The X-ray analysis revealed that the molecular unit of the compound consists of a captivating tetra-Cd-substituted sandwich-type polyoxoanion, accompanied by six elegantly protonated 1,2-diaminopropane as counter ions. The further novelty of the tetranuclear cadmium cluster lies in its occupied chlorine atom sites. This makes it highly susceptible to coordinate reactions with nitrogen on polycyclic aromatic hydrocarbons, thereby exhibiting different fluorescent signals that facilitate the identification and detection of these carcinogenic substances in methanol.

Two Cd-Based Luminescent Coordination Polymers Constructed from a Truncated Linker.

Two cadmium coordination polymers, WSU-30 and WSU-31, were synthesized through solvothermal methods by using the low-symmetry TPE-based linker m-H4ETTC. The m-H4ETTC linker and both coordination polymers were fully characterized by using single-crystal X-ray diffraction, infrared spectroscopy, and photoluminescent emission spectroscopy. Structural analysis of WSU-30 and WSU-31 showed that each compound contains previously unknown tetranuclear cadmium(II) secondary building units. The topological analysis revealed that the 4,8-connected net of WSU-30 contains the underlying topology, alb-4,8-P21/c-1, while the mixed linker WSU-31 possesses a 3,10-connected net known as 3,10T31 topology. If the m-ETTC linker is considered as two 3-connected nodes, WSU-30 possesses a very rare 3,3,8-connected 3,3,8T25 topology, and WSU-31 possesses a previously unknown 3,12-connected net, named 3,12T61.

An ultra-stable Cadmium(II) Coordination Framework Constructed From the new Bi-Functional Ligand and Application as Fluorescent Probe for Acetylacetone and Antibiotics

In the last thirty years, light-emitting metal organic frameworks (MOFs) sensors have attracted immense interest by scientists because these functional coordination materials possess good framework stability and high surface areas, and excellent stability in adsorption, separation, catalysis, etc. These MOFs-based sensors have the broad applications in the national security, surrounding protection and mankind's health. In this work, a new bi-functional ligand H3L (H3L = 4'-(1H-tetrazole-5)-biphenyl-2,3-dicarboxylic acid) simultaneously containing tetrazole and carboxylate groups can be synthesized. Further, the ultra-stable tetrazolium Cadmium (II) MOFs {[Cd2 (μ7-L) (μ3-OH) (H2O)2]·1.3H2O}n (1) has been successfully prepared under the solvo-thermal conditions. In 1, neighboring tetranuclear cadmium (II) building blocks are inter-linked through the bridging tetrazole moieties and aromatic bi-phenyl backbones forming the 3D micro-porous framework. It is interesting that 1 exhibits excellent chemical stability, the coordination framework of 1 can be kept not only in various different solvents but also the water environment with pH varying from 2 to 12 for 24 h. Powder X-ray diffraction (PXRD) patterns have been investigated demonstrating these bulky as-synthesized samples 1 are pure phases. Compared with other coordination polymers, 1 has some other advantages such that 1 possesses good water dispersibility, excellent photo-luminescence emissions and fluorescence stability, which has the potential to be utilized as the excellent chemical sensor. Fluorescent characterization reveals that 1 also can behave highly sensitive and real-time discrimination of acetylacetone (Hacac) with good reusability (high quenching efficiency Ksv for Hacac: 2.5 × 105 M−1) and extremely low detection limit values (For Hacac: 35 μM). On the other hand, 1 can behave highly sensitivity, recyclability and real-time chemical sensing for antibiotics nitrofurazone (NFZ) and nitrofurantoin (NFT) (Ksv for NFZ: 5.9 × 106 M−1 and NFT: 9.0 × 106 M−1) and extremely low detection limit values (For NFZ: 2.2 μM and NFT: 1.4 μM).

Syntheses, crystal structures and photo physical aspects of azido-bridged tetranuclear cadmium (II) complexes: DFT/TD-DFT, thermal, antibacterial and anti-biofilm properties

In this work we have reported two novel tetranuclear Cd(II) complexes viz. [Cd4 (LOMe)2 (μ1,1-N3)3 (μ1,3-N3)]n (1) and [Cd4 (LOEt)2 (μ1,1-N3)3(OAc)]2 (2) where (H2LOMe) and (H2LOEt) are two important less explored salen-type Schiff base ligands. Both of the complexes have been characterized by using routine spectroscopic techniques, elemental analyses (C, H and N), X-ray powder diffraction pattern (PXRD) and thermal analysis by TGA along with single x-ray crystallography. The complete structural study discloses that in both cases the fully deprotonated ligand [LOMe]2- or [LOEt]2- utilized all potential coordination sites to accommodate four Cd(II) ions. Complex 1 is a one-dimensional polymer with azide (N3) linkage having both (μ1,1 end on) and (μ1,3 end-to-end) azido bridging but complex 2 is a discrete octanuclear ensamble where two [Cd4(O)4(N)2]2+ units bridged to each other showing μ1,1 end on end on azide bridging. Exploration of photo physical properties in DMSO solvent reveals that Cd(II) complexes enhance appreciably the fluorescence behavior over free Schiff base ligands (H2LOMe) and (H2LOEt). DFT calculations performed at B3LYP/def2-TZVP level of theory reveal both the energetics and composition of FMOs in these complexes and also show electrophilic and nucleophilic areas via molecular electrostatic maps [ESP] concept. The antibacterial, membrane damage assay and anti-biofilm properties of complexes 1 and 2 were investigated very carefully against some important Gram-positive and Gram-negative bacterial strains.

Structural and luminescent properties of a tetranuclear cage-type cadmium(II) carboxylate cluster containing a V-shaped water trimer

The structural characterization of tetranuclear cage-type cadmium(II) carboxylate [Cd4(2-cpida)2(2,2′-bpy)6]·(2,2-bpy)·(ClO4)·3H2O (1) (2-H3cpida = N-(2-carboxyphenyl)iminodiacetic acid, 2,2′-bpy = 2,2′-bipyridine) is described. H-bonding interactions between three lattice water molecules form a V-shaped trimer (H2O)3, which is stabilized by 1. In addition, luminescence investigations revealed that 1 shows enhanced emissions as compared with free 2-H3cpida in the liquid state.

One novel 3D tetranuclear cadmium coordination polymer based on 2,3′,4,5′-biphenyltetracarboxylic acid: Synthesis, crystal structure and luminescence

One novel 3D cadmium coordination polymer, namely, {[Cd2(bptc4−)(ox2−)0.5(H2O)2]·4.5H2O}n (1), has been hydrothermally synthesized through a reaction of 2,3′,4,5′-biphenyltetracarboxylic acid (H4bptc) with divalent cadmium salt in the presence of a second ligand (ox=oxalic acid). X-ray single crystal structure analysis reveals that tetranuclear cadmium clusters are formed by linking two Cd1 and two Cd2 ions with carboxyl groups. Each ox2− ligand, with a bidentate chelating mode, connects two Cd2 ions from two adjacent tetranuclear clusters to afford 1D zigzag cadmium cluster chains. Furthermore, 1D chains are connected by bptc4− ligands to extend a 3D framework with one-dimensional channels along the [001] direction. From a topology view, complex 1 exhibits an unprecedented 2-nodal 4, 10-connected net with the Schläfli symbol of {46}2{49. 512.622.72}. The luminescence analyses reveal that complex 1 shows an emission maximum at 437nm, which may be attributed to the intra-ligand transition. A red shift of 31nm compared with H4bptc ligand was observed and the luminescent decay lifetime is 2.74ns, which indicates that it might be a potential blue light-emitting candidate. In addition, it was also characterized by elemental, IR spectra, PXRD and TG analyses.

Synthesis, crystal structures, and properties of two novel cadmium(II)–organic frameworks based on asymmetric dicarboxylate and N-donor ligands

Two novel cadmium(II)–organic frameworks with asymmetric dicarboxylate and N-donor ligands, namely [Cd(cpa)(phen)]n (1) and {[Cd2(cpa)2(bpy)1.5]·0.5H2O}n (2) (H2cpa=3-(4-benzoic)propionic acid, phen=1,10-phenanthroline, bpy=4,4′-bipyridine) have been hydrothermally synthesized and characterized by elemental analyses, FT-IR spectra, single-crystal X-ray diffraction analyses, TGA, powder XRD and fluorescent measurements. 1 displays a double zigzag chain structure containing 8-number and 22-number circles. 2 Shows a 6-connected 3D polymer network based on tetranuclear cadmium cluster units. The most striking feature of 2 is that a pair of identical 3D networks are interlocked with each other to the form a 2-fold interpenetrated 3D α-Po structural topology. The diverse structures of two complexes indicate that the skeleton of N-donor ligands plays a great role in the assembly of such different frameworks. In addition, the thermal stabilities, XRD and photoluminescence properties of 1–2 were also studied.

A chiral mixed metal–organic framework based on a Ni(saldpen) metalloligand: synthesis, characterization and catalytic performances

A three-dimensional (3D) chiral mixed metal-organic framework [Cd4Cl(Ni-L)3(Ni-HL)(H2O)6(DMF)]·4DMF (CMOF 1) based on a new enantiopure dicarboxyl-functionalized Ni(saldpen) metalloligand Ni-H2L and a novel tetranuclear cadmium cluster [Cd4Cl(CO2)7(CO2H)] has been synthesized and characterized by elemental analyses, IR and UV-vis spectra, thermogravimetric analysis, nitrogen and carbon dioxide adsorption, powder and single-crystal X-ray diffractions. Each tetranuclear-cadmium cluster in 1 is linked by eight Ni-L ligands, and each Ni-L ligand is linked by two tetranuclear-cadmium clusters to generate a 3D framework with 1D open channels (∼1.1 × 0.9 nm(2)) along the b-axis. Based on its good stability, permanent porosity, Lewis acid sites and moderate uptake for CO2, 1 can be used as a self-supported heterogeneous catalyst for the synthesis of optically active propylene carbonate by asymmetric cycloaddition of CO2 with racemic propylene oxide under relatively mild conditions.

A tetranuclear cadmium(II) complex based on the 2-(quinolin-8-yloxy)acetonitrile ligand

The hydrothermal reaction of 2-(quinolin-8-yloxy)acetonitrile and Cd(ClO(4))(2) yielded the noncentrosymmetric coordination complex tetrakis[μ-2-(quinolin-8-yloxy)acetato]tetrakis[μ-2-(quinolin-8-yloxy)acetonitrile]tetracadmium tetrakis(perchlorate) dihydrate, [Cd(4)(C(11)H(8)NO(3))(4)(C(11)H(8)N(2)O)(4)](ClO(4))(4)·2H(2)O. The local coordination environment around the Cd(II) cation can be best described as a capped octahedron defined by two N atoms and five O atoms from three ligands. The Cd(II) cations are linked by the ligands with Cd-O-Cd and Cd-O-C-C-O-Cd bridges, forming tetranuclear units, there being two independent tertranuclear units in the structure. The fourfold rotoinversion centre sits at the centre of each Cd(4) core. The two perchlorate anions in the asymmetric unit are linked by the water molecule through O-H...O hydrogen bonds.

Synthesis, structure, photoluminescence and theoretical calculations on a novel tetranuclear Cd(II) complex based on (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid

Abstract A novel tetranuclear cadmium complex {Cd2[(CH3)2PPDA]2(CH3OH)Cl4}2 (1) [(CH3)2PPDA = dimethyl esterification of H2PPDA], was prepared from CdCl2·2.5H2O with (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid (H2PPDA) by solvothermal reaction in methanol, and characterized by single-crystal X-ray diffraction analysis, optical diffuse reflectance and photoluminescence. In 1, cadmium ions are bridged by Cl− ions into a tetranuclear oligomeric chain further connected into a 3D supramolecular network by intermolecular C H⋯Cl, O H⋯Cl, and C H⋯O hydrogen bonds. Compound 1 displays fluorescence with a lifetime value of ~ 5.88 ns in the visible region under visible-light excitation, and the origin of the luminescent emission is primary assigned to the combination of intraligand π–π* transition of (CH3)2PPDA ligand and ligand to ligand charge transfer from Cl− to (CH3)2PPDA which is probed by the density of state (DOS) calculations.

Synthesis, structures, and fluorescence of azido-bridged dinuclear and thiocyanato-bridged tetranuclear cadmium(II) complexes derived from N-isopropyl-N′-(1-pyridin-2-ylethylidene)ethane-1,2-diamine

A new azido-bridged dinuclear cadmium(II) complex [Cd2L2(μ 1,1-N3)2(ONO2)2] (1) and a new thiocyanato-bridged tetranuclear cadmium(II) complex [Cd4L4(μ 1,3-NCS)4(NCS)4] (2), where L is the tridentate Schiff base N-isopropyl-N′-(1-pyridin-2-ylethylidene)ethane-1,2-diamine, were prepared and characterized. X-ray single crystal structure determination reveals that 1 is a centrosymmetric end-on azido-bridged dinuclear cadmium(II) compound and 2 is a rarely seen centrosymmetric end-to-end thiocyanato-bridged tetranuclear cadmium(II) compound. Cd in each complex is in distorted octahedral coordination. In the crystal structure of 1, the dinuclear cadmium(II) molecules are linked through N–H ··· O hydrogen bonds to form a 3-D network. In the crystal structure of 2, the tetranuclear cadmium(II) complex molecules are linked through N–H ··· S hydrogen bonds to form 1-D chains. The thermal stability and preliminary fluorescence properties of the complexes were investigated.

Crystal Structure and Photoluminescence of a Tetranuclear Cadmium Complex

A novel tetranuclear cadmium complex ([{Cd(C15H8O7S)(H2O)(DMSO)}3{Cd(C15H8O7S)(H2O)2}]·3DMSO·H2O) was obtained by the self-assembly of Cd(II) with 5,7-dihydroxyflavone-6-sulfonate. The complex was characterized by 1H NMR, IR, elemental analysis and X-ray single-crystal diffraction studies. It crystallizes in triclinic, space group . In the complex, the chelate atoms of Cd(II) are all from oxygen. Four Cd(II) are connected via the carbonyl and 5-hydroxyanion of four ligands and form an approximate square. Four ligands locate at two sides of the square, and two of them at the same side are almost parallel and exist aromatic π-π stacking. Ligands on the opposite side of the square are nearly perpendicular. The result of the luminescent studies indicated that the solid of the complex shwed photoluminescent properties because of a combination of coordination, hydrogen bonding and π-π stacking interaction in the molecule structure. The complex emits green fluorescence (λem=496 nm) when it is excited at the wavelength of 440 nm.

Di-μ3-chlorido-tetra-μ2-chlorido-dichloridobis(dimethylformamide-κO)hexakis(1H-imidazole-κN3)tetracadmium

The centrosymmetric mol­ecule of the title complex, [Cd4Cl8(C3H4N2)6(C3H7NO)2], contains four CdII atoms, six imidazole, two dimethyl­formamide and eight chloride ligands. The structure shows a novel chloride-bridged tetra­nuclear cadmium quasi-cubane cluster. The coordination geometry of all CdII atoms is distorted octa­hedral, with the two metal atoms in the asymmetric unit in different coordination environments. One of the Cd2+ ions is coordinated by five Cl− ions and by one N atom from an imidazole ligand, while the second is coordinated by three chloride ligands, two N atoms from two imidazole ligands and one O atom from a dimethyl­formamide mol­ecule. Inter­molecular N—H⋯Cl hydrogen bonds link the mol­ecules into a two-dimensional polymeric structure parallel to the ab plane.

First Report on Thermally Stable Cadmium Carbonyl Complex Containing an Interesting Chloroaryl Bridge: Isolation and Characterization

Abstract A novel thermally stable tetranuclear cadmium carbonyl complex [Cd(CO)3(C6H3Cl)]4·2H2O has been synthesized for the first time through a green path with an overall yield of 35%. The synthetic route features a new pathway, creating the two ortho-positions with respect to the chlorine atom in the aryl rings for bridging two cadmium metal centers. The title complex has been characterized by microanalytical, infrared spectroscopic, and thermal methods while its structure has been established by single-crystal X-ray diffraction supported by 1H, 13C, and 113Cd NMR data.

Poly[μ3-hydroxido-μ6-sulfato-μ3-(1,2,4-triazolato-κ3N1:N2:N4)-dicadmium(II)]: a cadmium–triazolate coordination polymer with a pseudo-cubane-like tetranuclear cluster

The title complex, [Cd(2)(C(2)H(2)N(3))(OH)(SO(4))](n), is a three-dimensional metal-organic framework consisting of pseudo-cubane-like tetranuclear cadmium clusters, which are formed by four Cd(II) atoms, two sulfate groups and two hydroxide groups. The tetranuclear cadmium clusters are connected into a layered substructure by Cd-O bonds and adjacent layers are linked by triazolate ligands into a three-dimensional network. A photoluminescent study revealed that the complex exhibits a strong emission in the visible region which probably originates from a π-π* transition.

Synthesis, Crystal Structure, Photophysical Properties, and DFT Calculations of a Bis(tetrathia-calix[4]arene) Tetracadmium Complex

Thiacalix[4]arenes are a unique family of polydentate ligands that offer a combination of four soft sulfur atoms together with four hard phenol oxygen atoms for binding to metal ions. In this study, the tetranuclear cadmium (II) complex Cd 4 II (tca)2·1.5CH2Cl2 (tca4− = tetra-anionic p-tert-butylthiacalix[4]arene) (1) was synthesized by reaction of a deprotonated p-tert-butylthiacalix[4]arene and various CdII salts. The structure of 1 was established by single crystal X-ray diffraction analysis. The neutral complex 1 contains a square arrangement of four cadmium (II) ions sandwiched between two tca4− ligands that have a ‘cone’ conformation similar to that of the free ligand. The absorption and emission properties of the free ligand H4tca and complex 1 have been recorded and explained by DFT calculations of the molecular orbitals and electronic transitions between them. The tetranuclear cadmium (II) complex Cd 4 II (tca)2·1.5CH2Cl2 (tca4− = tetra-anionic p-tert-butylthiacalix[4]arene) (1) was synthesized by reaction of a deprotonated p-tert-butylthiacalix[4]arene and various CdII salts. The absorption and emission properties of the free ligand H4tca and complex 1 have been recorded and explained by DFT calculations of the molecular orbitals and electronic transitions between them.

Pseudopolymorphism deriving from variable π⋯π stacking modes: Discrete tetranuclear cadmium(II) phosphonate clusters with 1,10-phenanthroline as auxiliary ligand

Hydrothermal reactions of Cd(ClO 4) 2 or CdSO 4 with [(dibenzylamino)-methyl]-phosphonic acid (H 2L) as well as 1,10-phenanthroline (phen) afforded two tetranuclear cadmium(II) phosphonate cluster compounds with the formula of [Cd 4(L) 4(phen) 4]· nH 2O ( n = 4 or 6). The two compounds are supramolecular pseudoisomers which derive from two different π⋯π stacking modes of the 1,10-phenanthroline ligands in them, and such supramolecular isomerism is induced by the distinct counter-ions of the starting cadmium source.

Synthesis and structures of three d 10 metal coordination polymers constructed from flexible polycarboxylate and 1,10-phenanthroline ligands

Three novel d 10 metal coordination polymers, {[Cd(H 2odpa)(phen) 2]·H 2O} n ( 1), [Cd 2(odpa)(phen)(H 2O) 2] n ( 2), {[Zn 4(odpa) 2(phen) 2(H 2O) 2]·H 2O} n ( 3), (H 4odpa = 4,4′-oxydiphthalic acid, phen = 1,10-phenanthroline) were obtained with different metal/ligand ratios through hydrothermal method and characterized. Compound 1 forms a one dimensional zigzag chain, in which two phen ligands chelate to one cadmium atom. Compound 2 shows a three dimensional network structure comprised of new tetranuclear cadmium clusters as the nodes and (odpa) 4− anions as the linkers, exhibits an unusual topological structure. Compound 3 is an unprecedented three dimensional polymer based on octanuclear zinc clusters cross-linked by (odpa) 4− anions. In 1– 3, central Cd II/Zn II ions and (odpa) 4− ligand display completely different coordination modes and conformations. In addition, the thermal stabilities and photoluminescence properties of 1– 3 were also studied.

Assembly of tetra, di and mononuclear molecular cadmium phosphonates using 2,4,6-triisopropylphenylphosponic acid and ancillary ligands

The reaction of ArPO(3)H(2) (Ar = 2,4,6-iPr(3)-C(6)H(2)) with Cd(CH(3)COO)(2).2H(2)O using various co-ligands such as methanol, dimethylformamide (DMF) and 3,5-dimethylpyrazole (DMPZH) resulted in the formation of tetranuclear assemblies [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(CH(3)OH)(4)].3(CH(3)OH) (1), [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(DMF)(4)].3(DMF) (2) and [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(DMF)(2)(DMPZH)(2)].2(DMF).2(H(2)O) (3). In all of these compounds the tetranuclear cadmium array, containing two five-coordinate and two six-coordinate cadmium atoms, is held together by two mu(4) capping [ArPO(3)](2-) and four anisobidentate mu(2) [ArPO(2)(OH)](-) ligands. Each cadmium atom is bound to an additional ancillary ligand. The reaction of ArPO(3)H(2) with Cd(CH(3)COO)(2).2H(2)O in the presence of the chelating ligand 2,2'-bipyridine (bipy) leads to the exclusive formation of the dinuclear assembly [Cd(2)(ArPO(3)H)(4)(bipy)(2)].(CH(3)OH)(H(2)O) (4). The latter contains an eight-membered Cd(2)P(2)O(4) inorganic ring formed as a result of the bridging coordination action of two anisobidentate mu(2) [ArPO(2)(OH)](-) ligands. Each cadmium atom is bound by one chelating bipy and one monodentate [ArPO(2)(OH)](-) ligands. Use of four equivalents of 3,5-dimethylpyrazole leads to the formation of the mononuclear derivative [Cd(ArPO(3)H)(2)(DMPZH)(4)] (5). The molecular structure of the latter comprises of a central cadmium atom surrounded by six monodentate ligands. Four of these are neutral pyrazole ligands that occupy the equatorial plane; the remaining two are anionic phosphinate ligands which are present trans to each other. The thermal analysis of 1 and 4 reveals that the char residue obtained at 600 degrees C consists predominantly of Cd(2)P(2)O(7).

Novel Cadmium(II) Phosphonatophenylsulfonate Cluster Compounds: Syntheses, Structures, and Luminescent Properties

Hydrothermal reactions of cadmium(II) salt with m-phosphonophenylsulfonic acid (H3L) and 1,10-phenanthroline (phen) or 4,4'-bipyridine (bipy) led to three novel cadmium(II) phosphonatephenylsulfonates, namely, [Cd-4(L)(2)(phen)(6)(Cl)(2)(H2O)(2)]center dot 14H(2)O (1), [Cd-6(L)(4)(phen)(8)]center dot 14H(2)O (2), and [Cd-3(L)(2)(bipy)(3)(H2O)(6)]center dot 4H(2)O (3). Compound 1 contains a tetranuclear cadmium(II) cluster in which four cadmium(II) ions are bridged by two tetradentate phosphonate groups. Compound 2 features a hexanuclear cadmium(II) cage in which six cadmium(II) ions are bridged by one tetradentate and three pentadentate phosphonate groups. The structure of compound 3 features a novel 3D network based on 1D chains of [Cd-3(L)(2)] cross-linked by 4,4'-bipy ligands; its topological structure is similar to that of CdSO4. Compounds 1-3 exhibit broad blue fluorescence emission bands at 408, 410, and 396 nm, respectively.