Preparation of SnO2 Nanoparticles from a New Tin(IV) Complex: Spectroscopic and Photoluminescence Studies

A new dimethyltin(IV) complex, {[Me₂Sn(O₂CNC₉H₆)]₂O}₂ (1), was prepared by reaction of dimethyltin(IV) dichloride with the quinoline-2-carboxylic acid and characterized by elemental analysis, IR, ¹H-, ¹³C-, ¹¹⁹Sn-NMR spectroscopes. The structure of 1 was determined by single-crystal X-ray diffraction. The results showed that 1 is a tetranuclear, centrosymmetric dimeric, and contains two endo-cyclic five-coordinated and two exo-cyclic six-coordinated tin atoms and a N-atom of the 2-quinaldic carboxylate ligand coordinated to exo-cyclic tin. Complex 1 was utilized as a precursor for SnO₂ nanoparticles by direct thermal decomposition at 500 °C in air. The nano-structure of SnO₂ was characterized by scanning electron microscopy and X-ray powder diffraction. The SnO₂ core showed a band gap of ~4 eV determined from the UV/visible absorption spectrum. The SnO₂ nanoparticles show stable photoluminescence (PL) with an emission centered at 557 nm.     

Synthesis,spectroscopic studies and structure prediction of the new Tb(3-NH2PIC)3·3H2O complex

The synthesis, spectroscopic properties and structure prediction of the complex of Tb(III) with 3-aminopyridine-2-carboxylic acid (3-NH₂PIC) are described. The complex was characterized by elemental analysis and IR, absorption and emission spectra. The C, H and N elemental analysis consistent with the formulation of the compound as Tb(3-NH₂PIC)₃·3H₂O. This complex exhibits a luminescence intensity that is attenuated to that of its Eu⁺³ congener. The Sparkle model, used for structural computations of lanthanide complexes (SMLC), was applied to the new complex. The calculation used an INDO/S-CI model for determination of the electronic spectrum.     

Synthesis and structure of a novel tetranuclear 32-membered macrocycle of triphenyltin complex with pyridine-4-carboxylic acid N-oxide

The 32-membered stereoregular triphenyltin macrocycle: [Ph₃Sn (OCOC₅H₄NO)]₄·3(CH₂Cl₂) has been synthesized by the reaction of triphenyltin chloride with pyridine-4-carboxylic acid N-oxide. The complex was characterized by elemental analysis, FT-IR, NMR (¹H, ¹¹⁹Sn) spectra and X-ray crystallography. Single crystal X-ray diffraction data reveal that the complex is highly symmetrical tetranuclear cyclic complex with the ligand pyridine-4-carboxylic acid N-oxide bridging the adjacent tin atoms. All four tin atoms are five-coordinated resulting in trigonal bipyramidal geometry. And the complex showed good thermal stability and high antitumor activity.     

A triple chain coordination polymer constructed from ZnTPP and a bis(4,4′-dipyridylamine) ligand

A novel coordination polymer [(ZnTPP)₃ L¹]_n·(DMF)_2n 1 (ZnTPP = zinc(II) tetraphenylporphyrinate) has been hydrothermally synthesized from a tetrapyridyl ligand N,N,N′,N′-tetra(4-pyridyl)-1,4-phenylenediamine (L¹) and characterized by elemental analysis, IR, and single-crystal X-ray diffraction analyses. In the crystal, L¹ utilizes all four pyridyl N atoms to coordinate at the axial positions of two different ZnTPP units. The first utilizes two axial positions for coordination, and the second coordinates at only one of the axial positions. Thus, the former ZnTPP units and two pyridyl nitrogens of L¹ ligands are linked alternately to afford a zigzag chain, and two of the latter porphyrin units are appended to both sides of each repeating unit of the zigzag chain by coordination to the remaining two nitrogens of each L¹ ligand. Interestingly, the appended porphyrins form two straight lines at both sides of the zigzag chain by the linkage of π???π interactions between the phenyl rings. Finally, a triple chain is formed. The solid state emission of 1 is also studied.     

Synthesis,structures, and photoluminescent properties of two uranium complexes constructed by a flexible zwitterion ligand

Two novel uranium complexes were constructed by using a tripodal flexible zwitterion ligand 1,1′,1″-(2,4,6-trimethylbenzene-1,3,5-triyl)-tris(methylene)-tris(pyridine-4-carboxylic acid) trichlorine (H₃LCl₃). Reaction of uranyl acetate dihydrate and H₃LCl₃ in aqueous solution affords (UO₂)₄L₂Cl₄(μ₃-O)₂^.4H₂O (1), which contains tetranuclear motifs, resulting in the two dimensional structure. UO₂L₂^.2NO₃^.H₂O (2) obtained via the reaction of H₃LCl₃ and uranyl nitrate hexahydrate, which displays a three dimensional structure. The structures were detected by single crystal X-ray crystallography, elemental analysis (EA), infrared (IR) spectroscopy, and thermogravimetric analysis (TGA). Furthermore, luminescent properties were also investigated.     

Two birds with one stone: Self-assembly of metal–organic coordination complexes with discrete metallamacrocycle and 1D zigzag chain based on a flexible dicarboxylate ligand

To assemble metal–organic coordination complexes, a flexible dicarboxylate ligand, 2,2′-(4,6-dimethyl-5-nitro-1,3-phenylene)bis(methylene)-bis-(sulfanediyl)dibenzoic acid (H₂L), has been designed and synthesized. Using the flexible ligand to assemble with copper ions, a mixture of two metal–organic complexes, Cu₂(L)₂(py)₄·4dmso (1) and Cu₂(L)₂(py)₆·3dmso·py (2), has been generated by solvothermal technology in one glass tube. Through increasing the mole fraction of pyridine, the pure phase of complex 2 was obtained. Both complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex 1 is a discrete rectangular macrocycle. The guest solvents of dimethyl sulfoxide molecules were trapped in the cavity of rectangular metallmacrocycle, resulting in the formation of an infinite supramolecular metal–organic nanotube through van der Waals interactions between the guests and the host molecules. In complex 2, the flexible ligand adopts a syn conformation to assemble with copper ions to form an infinite one-dimensional zigzag chain.     

Synthesis and fluorescence properties of rare earth metal ion–polymer ligand–low molecular weight ligand ternary complexes

Eu³⁺-containing polymer ternary complexes were synthesized using different kinds of functional polymers such as poly(benzylmalonic acid styrene) (PBMAS), poly(benzylacetone styrene) (PBAAS), and poly(benzyl-azo-o-hydroxybenzoic acid styrene) (PBAHBAS) as polymer ligands. The structures of the complexes were investigated by elemental analysis and IR spectroscopy. The fluorescence intensity of Eu³⁺–polymer–TTA (2-thenoyltrifuoroacetone ion) complexes was decreased in the order PBMAS(61) > PBAAS(42) > PBAHBAS(32). In system of Eu³⁺–PBMAS–low molecular weight ligand, the emission spectrum shape, the fluorescence intensity, and the wavelength of the maximum emission peak were changed when the low molecular weight ligand was varied. The fluorescence intensity of the Eu³⁺–PBMAS–TTA ternary complex was 610 times stronger than that of the Eu³⁺–PBMAS binary complex and 160 times stronger than that of Eu³⁺–PBMAS–oxine complex. The fluorescence intensity of the Eu³⁺–PBAAS–TTA complex was enhanced greatly when the proper mol ratio of HTTA/Eu³⁺ and pH in the reaction were chosen.     

Two novel supramolecular isomers based on 2,2′-biimidazole derivative and zinc ions: Syntheses,structures and luminescent properties

Two Zn(II)-2,2′-biimidazole derivative supramolecular isomers 1 and 2 formulated as [Zn(L)] · 2H₂O (H₂L = 4,4′-(1H,1′H-2,2′-biimidazole-1,1′-diylbis(methylene))dibenzoic acid) have been synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Complex 1 exhibits a 2D four-connected network with (4³.6³) topology when the zinc center and the L^2? ligand act as four-connected nodes (or a distorted (4,4) grid if the [Zn₂(imidazole)₄] units are considered as four-connected nodes). Complex 2 shows a novel four-connected twofold interpenetrated net with (4².6².8²) topology when the zinc center and the L^2? ligand act as four-connected nodes (or a twofold interpenetrated α-Po topology when [Zn₂(imidazole)₄] units are identified as six-connected nodes). Moreover, complexes 1 and 2 both exhibit strong luminescent properties at room temperature.     

Synthesis, Structural Investigation and DFT Calculations of Cadmium (II) Fluorine-Substituted β-Diketonate: A Precursor to Producing Pure Phase Nano-Sized Cadmium (II) Oxide

A novel aza-aromatic base adduct of a cadmium(II) fluorine-substituted β-diketonate, [Cd(dmp)(ttfa)₂]_n(1), (“dmp” is an abbreviation for 2,9-dimethyl-1,10-phenanthroline and “ttfa” is an abbreviation for thenoyltrifluoroacetonate) was synthesised and characterised by elemental analysis and IR, ¹H NMR and ¹³C NMR spectroscopy and studied by thermal as well as X-ray crystallography. The single-crystal structure of this complex shows that the coordination number of the Cd²⁺ ion is six with two N-donor atoms from the dmp ligand and four O-donors from ttfa. Self-assembly of this complex was mediated by CH···F–C and π–π stacking interactions. The supramolecular features of these complexes are controlled by weak directional intermolecular interactions. The structural energy of the title complex was determined by density functional theory calculations. The calculated HOMO–LUMO gap is 0.131 a.u. (3.474?eV). The CdO nano-particles were obtained by thermolysis of 1 at 180?°C with oleic acid as the surfactant. Scanning electron microscopy showed that the size of the CdO particles is ~35?nm.     

Hydrogenation of α-enaminoketones with cobalt phosphine-modified catalysts

The synthesis of α-enamines and hydrogenation of these compounds were studied using cobalt-modified complexes. Cobalt complexes were characterized by ¹H, ¹³C and ³¹P NMR, elemental analysis and IR spectroscopy. Furthermore, the molecular structures of complexes C1–C2 and C4–C5 have been determined by single-crystal X-ray diffraction. All cobalt complexes investigated were active catalysts for the hydrogenation reaction. The best catalytic activity was obtained with an ortho-substituent in the phosphine ligand. Noteworthy, the reduction was chemoselective over the double bond.     

New fluorescence active cellulosics prepared by a convenient acylation reaction

Novel, fluorescence active cellulosic polymers with high degree of functionalization of up to 1.0 were synthesized in homogeneous phase (cellulose in N,N-dimethylacetamide/LiCl and 6-O-thexyldimethylsilylcellulose in pyridine) with a mixed anthracene-9-carboxylic/p-toluenesulfonic acid anhydride. This novel and effective synthetic method yield the pure carboxylic acid esters of the polymers, which were characterized by means of FTIR- as well as ¹H and ¹³C NMR-spectroscopy. The polymers show typical fluorescence spectra, which are identical with the non-bond anthracene-9-carboxylic acid. Received: 26 August 1997/Accepted: 8 September 1997     

Crystal structures,DFT calculations and biological activities of three mercury complexes from a pentadentate thioether ligand

Three mercury complexes from a symmetric pentadentate ligand 2, 6-bis (8-quinolinyl thiomethyl) pyridine (L) have been prepared by the method of diffusing of diethyl ether or diisopropyl ether. The structures of the complexes have been identified by elemental analysis (EA), infrared spectra (IR) and single-crystal diffraction, and are composed of discrete mononuclear units in complexes 1 and 2 and binuclear units in complex 3. Especially, the valence of Hg in complex 3 is reduced to − 1 in-situ during self-assembly and HgHg σ bond is formed, which is further evidenced by the frontier orbital and natural bond orbital (NBO) properties calculated by DFT method. The antibacterial and antifungal activities of the ligand and the three complexes were also determined, which prove foundation information for research and application in pharmaceutical chemicals.     

Bis diallyl dithiocarbamate Pt(II) complex: synthesis,characterization, thermal decomposition studies,and experimental and theoretical studies on its crystal structure

Platinum dithiocarbamate (DTC) complex has been synthesized from the ligand diallyl DTC, and its structure was established from elemental analysis, IR, NMR, and single-crystal X-ray analyses to be Pt[S₂CN(C₃H₅)₂]₂. The thermal properties were studied using a simultaneous thermal analyzer, and showed two main steps of decomposition. The structural geometry analysis was determined using X-ray diffraction and Density Functional Theory (DFT) calculations. The single-crystal X-ray analysis showed that the complex has a square planar geometry. The diallyl groups of the DTC ligands are not symmetrical making the complex non-centrosymmetric, and the complexes are stacked with intermolecular ring–ring interactions. The DFT calculations were performed to obtain the theoretical information and compared with the experimental data obtained from the experimental crystal structure.     

Synthesis and crystal structure of [nBu4N][Er(pic)4] · 5.5H2O: a new infrared emitter

The new erbium(III) complex of picolinic acid (Hpic), [ⁿBu₄N][Er(pic)₄] · 5.5H₂O, was synthesized and the crystal structure determined by single-crystal X-ray diffraction. The compound was further characterized using IR, Raman, ¹H NMR and elemental analysis. The picolinate ligands (pic⁻) are coordinated through N,O-chelation to the erbium cations, as shown by X-ray diffraction and spectroscopic results, leading to an eight coordinate complex. Photoluminescence measurements were performed for this compound which exhibits infrared emission.     

Zinc and thiocyanate-mediated oxazolidine ring formation in a trinuclear zinc(II) complex: Synthesis,structure, and properties

A novel trinuclear zinc(II) complex, [Zn₃L₂(NCS)₂], where L is the deprotonated form of 2-(3-(2-(2-hydroxy-3-methoxybenzylideneamino)ethyl)oxazolidin-2-yl)-6-methoxyphenol (H₂L), has been unexpectedly prepared from the reaction of Schiff base ligand 2-((2-(2-hydroxyethylamino)ethylimino)methyl)-6-methoxyphenol (HL′) with 3-methoxysalicylaldehyde, ammonium thiocyanate, and zinc nitrate in methanol. The complex has been characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction studies. It is interesting that the Schiff base ligand HL′ used to prepare the complex was transferred to a novel ligand H₂L, bearing newly formed oxazolidine ring. Zinc ion and thiocyanate anion may be the essential factors for the cyclorization. Thermal stability and fluorescent property of the complex were also studied.     

Construction of a novel Cd(II) coordination polymer based on a flexible tripodal carboxylic acid and bimid coligands

A new coordination polymer was solvothermally prepared based on a semi-rigid multidentate carboxylic acid ligand and benzimidazole (bimid) ligand (H₃L = 4,4′,4″-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(oxy))tribenzoic acid): [Cd₂(L) (bimid) (DMF)₂]·(DMF)₃·(H₂O)₂ (1). The complex 1 was characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry measurement, elemental analysis and X-ray powder diffraction. Structure analysis reveals that complex 1 displays a rare doubly-interpenetrating (3, 5)-connected hms network with a point symbol {6³}{6⁹.8}. Moreover, the fluorescence and gas adsorption properties of the compound 1 were also explored.     

Syntheses, structures, and photoluminescence of two Cd(II) coordination polymers constructed from analogue (pyridyl)imidazole derivative and polycarboxylate acid

Two novel Cd(II) coordination frameworks based on a semirigid asymmetric ligand L and aromatic multi-carboxylate ligands, {[Cd₂L(btc)(H₂O)₂]·5H₂O}_n (1) and [Cd₂L₂(bdc)]_n (2) (L = (4-((2-(pyridine-2-yl)-1H-imidazol-1-yl)methyl)benzoic acid, H₃btc = 1,3,5-benzenetricarboxylic acid, H₂bdc = 1,3-benzenedicarboxylic acid), have been hydrothermally synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Due to various coordination modes and conformations of the semirigid asymmetric ligand, and carboxylate containing co-ligands, therefore, the two complexes exhibit structural and dimensional diversity. Complex 1 exhibits a novel 2D (3, 5)-connected network structure with (3·5²)(3²·5³·6⁴·7) topology. Complex 2 exhibits a novel 3D CdSO₄ topology, which is formed from different dinuclear cadmium units. In addition, the photoluminescence properties of the free ligand L, and complexes 1 and 2 were studied in the solid state at room temperature.     

A new di-μ-oxo bis[oxovanadium(V)] complex containing Schiff base ligand derived from 1,2-diaminopropane and 2′-hydroxy-4′-methoxyacetophenone: Synthesis, structure and catalytic properties

New dioxovanadium(V) complex bearing tridentate ligand of 1:1 condensation of 1,2-propylenediamine and 2′-hydroxy-4′-methoxyacetophenone has been synthesized and characterized by IR and ¹H NMR spectroscopy and elemental analysis. The single-crystal structure of the complex shows that each vanadium(V) ion is six-coordinate through three bonds to oxo groups and through bonds to the tridentate Schiff base ligand. The title complex is used as catalyst for the selective epoxidation of cyclooctene. The catalytic system described here is an efficient and inexpensive method for the oxidation of olefins, with the advantages of high activity, selectivity, and short reaction time.     

Hydrothermal Synthesis of a Nano-sized Mercury(II) N–N–O Donor Coordination Compound

A novel nano-structures mercury(II) coordination compound, [Hg (HPCIH) I₂] (1), (“HPCIH” is the abbreviation of 2-pyridinecarbaldehyde isonicotinoyl hydrazone) has been synthesized by a hydrothermal method that produces the coordination compound at nano size. The new nanostructure was characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction elemental analysis and IR spectroscopy. Compound 1 was structurally characterized by single crystal X-ray diffraction and the single-crystal structure of this complex shows that each mercury(II) center is five coordinated with two N-donor and one O-donor atoms from “HPCIH” ligand and two iodo anions. Self-assembly of this complexes is realized by CH····I, I····I and π–π stacking interactions. The supramolecular features in these complexes are controlled by weak directional intermolecular interactions.     

Direct Synthesis of CdO Nanoparticles from a Novel Nano-Rods Cadmium(II) 4,4-Difluoro-1-phenyl-1,3-butanedionate Nano Coordination Compound

A novel nano-rods cadmium(II) fluorine-substituted β-diketonate, [Cd(2,2′-bpy)(dfpb)₂] (1), (2,2′-bpy = 2,2′-bipyridine; dfpb = 4,4-difluoro-1-phenyl-1,3-butandion) has been synthesized by a sonochemical method that produces the coordination compound with nano dimensions. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction (XRD) elemental analysis and IR spectroscopy. Compound 1 was structurally characterized by single crystal X-ray diffraction. The single-crystal structure of this complex shows that the coordination number of the Cd^II ions is six with two N-donor atoms from the 2,2′-bpy ligand and four O-donors from two dfpb. Self-assembly of the complex occurs through CH···F–C and π–π stacking interactions. The supramolecular features of 1 are controlled by weak directional intermolecular interactions. CdO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by the Scherrer equation to be 20 nm. The morphology and size of the CdO samples were further observed using SEM.