A novel 3D double helix cobalt(II) coordination polymer: Synthesis, crystal structures and third-order non-linear optical properties

One new metal-organic complex formulated as {[Co(bipy)₃][Co₂(μ₂–ox)₃]}_n 1 (bipy = 2,2′-bipyridyl; ox = oxalate) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and UV–visible spectra. The complex 1 contains helical chains composed of left-handed and right-handed helices interlaced in pairs. The third-order non-linear optical (NLO) properties of the 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 5.75 × 10⁻³⁰ esu for 1 in a 2.36 × 10⁻⁴ mol dm⁻³ DMF solution.     

The chiral Zn(II)–Na(I) coordination polymer: Synthesis, crystal structure, thermal and optical properties

The chiral Zn(II)–Na(I) coordination polymer with formula [NaZn(acac)₂(AcO)(EtOH)] (1) has been synthesized, and characterized by ¹H NMR and FT-IR spectra, elemental, X-ray, and thermogravimetric analysis (TGA). X-ray crystallographic study revealed that 1 crystallizes in the non-centrosymmetric space groups P2₁2₁2₁ and exhibits a one-dimensional polymer chain. Linear optical properties were investigated by UV/Vis spectrophotometer techniques. Kurtz–Perry powder second-harmonic-generation (SHG) test confirms the non-linear optical (NLO) property of the grown crystal.     

A novel chloro-bridged tetranuclear cadmium(II) cluster with pyridyl-substituted nitronyl nitroxide: structure and magnetic properties

A tetranuclear cadmium(II) complex of 2(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1 H-imidazol-1-oxy 3-N-oxide (NIToPy) with CdCl₂,[Cd₄Cl₈(NIToPy)₄], has been structurally and magnetically characterized. The structure is based on a novel chloro-bridged tetranuclear cadmium quasi-cubane cluster, in which each cadmium atom is chelated by one NIToPy radical, and coordinated with four bridging chlorine atoms. The temperature dependence of the magnetic susceptibility measurements shows a weak ferromagnetic coupling between the radicals. An excellent simulation of the experimental data with the prism type four spins Hamiltonian H=−2J₁(S₁S₂+S₂S₃+S₃S₄+S₁S₄)−2J₂S₂S₄ obtained the parameters: J₁=1.12 cm⁻¹, J₂=−0.20 cm⁻¹, and g=2.04.     

Two rod-based 3-D lead(II) tetrafluoroterephthalate coordination frameworks with sra topology: Syntheses, structures, and properties

Two three-dimensional (3-D) Pb^II coordination frameworks [Pb(BDC-F₄)(CH₃OH)]_n (1) and [Pb(BDC-F₄)(DMF)(CH₃OH)]_n (2) have been prepared by the reactions of Pb(NO₃)₂ with a rigid dicarboxyl compound tetrafluoroterephthalic acid (H₂BDC-F₄) in different solvents. Single crystal X-ray diffraction reveals that both complexes show the unusual rod-based coordination networks with sra topology, although they crystallize in different space groups (C2/c and ). Their spectroscopic, thermal, and fluorescence properties have also been studied.     

New (κ-C,N)-palladacyclic complexes with benzimidazol-2-ylidene ligand: Synthesis, crystal structures and characterization

Reaction of unsymmetrical benzimidazolium bromides (1) with Ag₂O and subsequent transmetallation with chloro-bridged dinuclear palladacycle, [Pd(dmba)(μ-Cl)]₂ (dmba: N,N-dimethylbenzylamine) afforded benzannulated monocarbene complexes [Pd(dmba)(NHC)Cl], 2. The palladacycles (2a–c) were characterized by elemental analysis; NMR spectroscopy and the molecular structure of 2a and 2c were determined by X-ray crystallography.     

Structural correlations in nickel(II)–thiodiacetato complexes: molecular and crystal structures and properties of [Ni(tda)(H2O)3]

Triaqua(thiodiacetato)nickel(II) has been synthesized and studied by X-ray crystallography, thermal, spectral and magnetic methods. The compound crystallizes in the triclinic system, space group , in contrast to the related compound [Ni(tda)(H₂O)₃] · H₂O (orthorhombic) reported long time ago. As in other four Ni–tda derivatives, the metal atom exhibits an octahedral coordination and tda ligand adopts a fac-tridentate chelating role. The studied compound is closely related to [Zn(tda)(H₂O)₃]. In addition, a structural comparison of the binary and ternary Ni–tda derivatives reveals that auxiliary N-donor ligands bind the metal atom using the trans-positions towards the Ni–O(carboxylato) bonds, but not in trans to the Ni–S(thioether) bond.     

Thermal,optical, and water sorption properties in composite films of poly(ether imide) and bismaleimides: Effect of chemical structure

Two series of semi‐interpenetrating polymer network (semi‐IPN) composite films, PEI/bismaleimide (UTBM) and PEI/fluorinated BMI (UTFBM) were prepared using a thermoplastic PEI and two different crosslinkable imide moieties. The effects of chemical structure and content of crosslinkable imide moieties on thermal stability, dielectric properties, and water sorption have been investigated. Glass transition temperature and weight loss temperatures increased with increase in the content of crosslinkable imide moieties, indicating the enhanced thermal stability of the semi‐IPN composite films. The refractive indices of the semi‐IPN composite systems increased with increasing crosslinkable imide moieties due to the higher polarizabilities of atoms. The water sorption of the semi‐IPN composite films was significantly decreased by the incorporation of crosslinkable imide moieties, which are interpreted by morphological structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mullite-type EMBO4: synthesis,structural, optical,and vibrational properties of rare tin(II) borates with M = Al and Ga

Metal tin-(II)-borates are rarely studied mainly due to the susceptibility of either oxidation into tin(IV) or disproportionation into elemental tin(0) and tin(IV). We report mullite-type SnAlBO₄ and SnGaBO₄ ceramics produced by conventional solid-state synthesis in sealed quartz tubes at low pressure of 10^–7 MPa. Both compounds are isostructural to PbAlBO₄ as confirmed by Rietveld refinements of powder X-ray data. The crystal structures are highly influenced by the stereochemical activity of the 5s² lone electron pair of the Sn²⁺ cation measured by the Wang–Liebau eccentricity parameter. To further consolidate the structural features ¹¹⁹Sn Mössbauer, solid state NMR, Raman, IR and UV/vis spectroscopic measurements are performed. The ¹¹⁹Sn Mössbauer isomer shifts and the quadrupole splitting values confirm the SnO₄ coordination and Sn(II) valence states. Solid state ¹¹B, ²⁷Al and ¹¹⁹Sn NMR spectra provided insights into the local crystal-chemical environment. The vibrational properties are discussed from group theoretical analysis to mode assignments. SnAlBO₄ and SnGaBO₄, respectively, possess an electronic band gap of 3.73(9) and 3.21(4) eV calculated from the diffuse reflectance UV/Vis spectra.