Synthesis and Crystal Structure of a New 2D Honeycomb—like Cadmium （Ⅱ） Complex with Tripodal Ligand

A new cadmium (II) coordination polymer, [Cd(TTTMB)₂]‐(SO₄) · 21H₂O, where TTTMB =1,3, 5‐tris (imidazol‐1‐yl‐methyl)‐2,4,6‐trimethylbenzene, was obtained by self‐assembly of tripodal ligand TTTMB with CdSO₄·2.7H₂O in acetonitrile, and characterized by X‐ray crystallography. The crystal data belongs to monoclinic space group C_c with cell parameters a = 1.16891(4) nm, b=2.06671(6) nm, c = 2.48185(7) nm, β = 97.8560(10)°, R = 0.0487, wR = 0.1211. The results of structure analysis indicate that each TTTMB ligand coordinates three metal atoms and in turn each Cd(II) atom with octahedral coordination geometry connects six nitrogen atoms of imidazole group from six different TTTMB ligands to produce a 2D honeycomb network structure. There are a lot of water molecules linked by hydrogen bonds and occupied the channels formed intra‐ and inter‐sheets.     

Syntheses, crystal structures and properties of Co(II) complexes with N,N′-bis(3-pyridylmethyl)-1,4-benzenedimethyleneimine (bpb), and Cd(II), Hg(II) complexes with reduced bpb

Five novel coordination polymers, [Co(bpb)₂Cl₂] (1), [Co(bpb)₂(SCN)₂] (2), [Cd(H₄bpb)_0.5(dmf)(NO₃)₂] (3), [Cd₂(H₄bpb)Br₄] (4), and [Hg₂(H₄bpb)I₄] (5) [bpb=N,N′-bis(3-pyridylmethyl)-1,4-benzenedimethyleneimine, H₄bpb=N,N′-bis(3-pyridylmethyl)-1,4-benzenedimethylamine], were synthesized and their structures were determined by X-ray crystallography. In the solid state, complex 1 is a 1D hinged chain, while 2 has 2D network structure with the ligand bpb serving as a bridging ligand using its two pyridyl N atoms. The imine N atoms keep free of coordination and bpb acts as a bidentate ligand in both 1 and 2. Complexes 3, 4, and 5 with reduced bpb ligand, i.e. H₄bpb, show similar 2D network structure, in which ligand H₄bpb serves as a tetradentate ligand. Thermogravimetric analyses for complexes 1-5 were carried out and found that they have high thermal stability. The magnetic susceptibilities of compounds 1, 2 were measured over a temperature range of 75-300 K.     

Nano-architectural silica thin films with two-dimensionally connected cagelike pores synthesized from vapor phase

Novel mesostructured silica thin films were prepared on a Si substrate by a vapor-phase synthesis. Vapor of tetraethoxysilane (TEOS) was infiltrated into a surfactant film consisting of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer. Nanophase transition from a lamellar structure to a two-dimensional cage structure of a silica-surfactant nanocomposite was found under vapor infiltration. The rearrangement into the cage structure implies high mobility of the silica-surfactant composites in solid phase. The silica thin films have two-dimensionally connected cagelike mesopores and are isotropic parallel to the film surface. The structure of pores of the films is advantageous for next-generation low-k films. The mesoporous structure has a large lattice parameter d of approximately 102 A, silica layer thickness of approximately 58 A, pillar diameter in the middle of approximately 60 A, pore size of approximately 72 A, BET surface area of approximately 729 m(2)/g, and pore volume of approximately 1.19 cm(3)/g. The films synthesized by the vapor infiltration show a lower concentration of residual Si-OH groups compared to the films prepared by a conventional sol-gel method. The films show high thermal stability up to 900 degrees C and high hydrothermal stability. This method is a simpler process than conventional sol-gel techniques and attractive for mass production of a variety of organic-inorganic composite materials and inorganic porous films.     

The capillary electrophoresis separation of benzodiazepine drug using dextran sulfate and SDS as running buffer

Capillary electrophoresis has been applied the analyses of many clinical drugs due to its rapid, high-resolution separation. In this study, electrokinetic chromatography involving the combination of SDS and dextran sulfate, which are synthetic polymers, was examined in order to obtain high resolution. Use of 2% dextran sulfate (10,000 molecular weight), 20 mm SDS running buffer containing boric acid solution (pH 9.2) and a silica capillary (inner diameter of 75 micro m, effective length of 50 cm, 57 cm overall length) afforded separation of 10 kinds of benzodiazepines. The detection limit was 0.2 micro g/mL; additionally, reproducibilities were de fi ned as the peak height and migration time. The average peak height was 5.92% (2.46-17.61), whereas the average migration time was 0.44% (0.18-0.76; n = 5). This separations system can be applied to the analysis and measurement of other pharmaceuticals as well.     

Synthesis, structure and photophysical properties of a flavin-based platinum(II) complex

We synthesized a thiosemicarbazone-functionalized flavin (Fl-(H)TSC: 2-[2-(3,4-dihydro-7,8-dimethyl-2,4-dioxobenzo[g]pteridin-10(2H)-yl)ethylidene]-hydrazinecarbothioamide) and its Pt(II) complex [Pt(Fl-TSC)(2)], and characterized it using X-ray diffraction, UV-visible absorption and luminescence spectroscopy. X-ray structural analysis for [Pt(Fl-TSC)(2)] revealed that the structure of the isoalloxazine part was almost the same as that in lumiflavin (7,8,10-trimethylisoalloxazine), and the thiosemicarbazone moiety acted as a bidentate ligand to form a PtS(2)N(2) planar conformation. UV-visible absorption and luminescence spectra of these compounds were very similar to those of riboflavin, but the emission intensity and the lifetime decreased considerably. Theoretical calculations suggested that the charge-separated state (Fl˙(-)-TSC˙(+)) contributed to the faster quenching from the (1)π-π* emission state.     

Highly permeable mesoporous silica membranes synthesized by vapor infiltration of tetraethoxysilane into non-ionic alkyl poly(oxyethylene) surfactant films

Mesoporous silica membranes were prepared on porous alumina substrates by a vapor infiltration of tetraethoxysilane (TEOS) into a non-ionic poly(oxyethylene) (Brij56) surfactant film. Periodic mesostructured silica membranes were formed on both α- and γ-alumina substrates pre-treated with polystyrene. The polystyrene polymer plugged the pores of the alumina substrates and inhibited the deposition of silica in the alumina pores, resulting in the formation of a very thin silica membrane without a silica/alumina composite layer at the interface between mesoporous silica and the alumina substrates. The calcined mesoporous silica membrane showed very high nitrogen permeance (>10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹). The single gas permeation was governed by the Knudsen diffusion mechanism. The durability of the mesoporous silica membrane against moisture in air was improved by a silylation with trimethylethoxysiliane.     

Structure modulation of metal–organic frameworks via reaction pH: Self-assembly of a new carboxylate containing ligand N-(3-carboxyphenyl)iminodiacetic acid with cadmium(II) and cobalt(II) salts

Self-assembly of a new carboxylate containing ligand, N-(3-carboxyphenyl)iminodiacetic acid (H₃L), with Cd(II) and Co(II) salts under different reaction pH results in the formation of four new coordination polymers, namely [Cd(HL)(H₂O)] (1), [Co(HL)(H₂O)] (2), [Cd(HL)(H₂O)₄] (3) and [Cd₃(L)₂(H₂O)₉] · 7H₂O (4). Single crystal X-ray diffraction analysis indicates that 1 and 2 are isomorphous and isostructural with a 2D wave-like network structure, while 3 has a 1D zigzag chain structure. The complexes 1–3 were obtained at low pH (<7) which makes the ligands only partly deprotonated. However, complex 4, obtained at pH 7 with all the carboxylate groups deprotonated, exhibits a 2D network structure. The results suggest that the reaction pH is one of the key factors in the formation of the coordination architectures. In addition, the photoluminescence properties of the free ligand (H₃L) and complexes 1, 3 and 4 were studied in the solid state at room temperature. Moreover, the magnetic property of complex 2 was investigated.     

Zinc(II) Complexes with 1H‐Imidazol‐4‐yl‐Containing Polyamine Ligand

The protonation and Zn^II/Cu^II complexation constants of tripodal polyamine ligand N¹‐(2‐aminoethyl)‐N¹‐(1H‐imidazol‐4‐ylmethyl)‐ethane‐1,2‐diamine (HL) were determined by potentiometric titration. Three new compounds, i.e. [H₃(HL)](ClO₄)₃ ( 5 ), [Zn(HL)Cl](ClO₄) ( 6 ) and {[Zn(L)](ClO₄)}_n ( 7 ) were obtained by reactions of HL · 4HCl with Zn(ClO₄)₂ · 6H₂O under different reaction pH, and they were compared with the corresponding Cu^II complexes reported previously. The results indicate that the reaction pH and metal ions have remarkable influence on the formation and structure of the complexes.     

Benzoin reaction in water as an aqueous medium catalyzed by benzimidazolium salt

Benzoin reactions are catalyzed by N,N-dialkylbenzimidazole to yield α-hydroxy ketones; the reaction proceeds in water as an aqueous medium under mild conditions. The utility of these salts as pre-catalysts in these reactions has been demonstrated.