Search

A Pd6L8 type coordination driven self-assembly was constructed using a tripodal ligand L (L = N1,N3,N5-trimethyl-N1,N3,N5-tris[(pyridin-4-yl)methyl]-1,3,5-benzene tricarboxamide) and palladium nitrate. The self-assembly was fully characterised using one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance spectroscopy, electrospray ionization-mass spectroscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and elemental analysis. Use of high resolution transmission electron microscopy (HR-TEM) analysis confirms the discrete nature of the assembly with a dimension of ∼2.8 nm, consistent with the density functional theory optimised structure. The assembly acts as an efficient homogeneous catalyst for a copper and phosphine free Sonogashira reaction under mild and aerobic conditions in aqueous medium. The catalyst shows equal efficiency for both electron deficient and electron rich aryl iodides and bromides and is also suitable for use with aliphatic alkynes. The utility of the catalyst as a reusable heterogeneous catalyst in toluene was assessed up to the 3rd cycle without any significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

The spectral studies and structure of a ternary complex of copper(II) with 2-hydroxyacetophenone 3-hexamethyliminylthiosemicarbazonate (L2−) and 1,10-phenanthroline (phen) are reported. The thiosemicarbazone binds to the metal as a dianionic ONS-donor (L2−) ligand, and forms a complex of the stoichiometry [CuLphen]. The copper(II) complex was characterized by IR and UV/Vis spectroscopies, as well as by solid state room-temperature magnetic susceptibility. Spin Hamiltonian and bonding parameters of the compound are calculated from the EPR spectra. Computer simulation of EPR spectrum in DMF at 77 K aided the calculation of magnetic and bonding parameters of the compound. The structure of the compound is solved by single crystal X-ray diffraction. The geometry around copper is distorted square pyramidal. [Copyright &y& Elsevier]

Discrete metal-organic polyhedra (MOP) with nanosized cavities and/or clusters of MOP could be prepared when C3-symmetric facial ligands and a potential hexatopic Cu(II) ion are combined in the presence of perchlorate as a weak linker, while similar reaction conditions in the presence of a nitrate linker led to extended metal-organic frameworks made of MOP as supramolecular building blocks. [ABSTRACT FROM AUTHOR]

A dinuclear doubly bridged copper(II) complex [Cu 2 L 2 ] where L represents N, N′-bis(3-ethoxysalicylidene)-4-methyl-1,3-phenylenediamine has been synthesised. The ligand was characterised by elemental analysis and spectroscopic techniques such as 1H NMR, 13C NMR, FT–IR, UV–visible and ESI–mass. The copper(II) complex was characterised using partial elemental analysis, FT-IR and UV–visible spectral techniques. The solid state structure of the complex was carried out using single crystal X-ray diffraction. The crystallographic study reveals that the two copper(II) metal ions are four coordinated (O 2 N 2) via phenolate O and azomethine N atoms, forming an unusual geometry between tetrahedral and square-planar. Cyclic voltammetry of complex reveals two consecutive quasi-reversible one electron redox couples corresponding to CuII–CuII/CuII–CuI and CuII–CuI/CuI–CuI. Density Functional Theory (DFT) and Time-dependent density functional theory (TD–DFT) calculations were carried out for the determination of the optimized structures. The theoretically obtained fundamental vibrational frequencies show good agreement with observed values. The ligand binds to Cu(II) in 1:1 stoichiometry as determined by Job's plot and the binding constant is calculated as 6.8 × 102 M−1 in solution phase. The photoluminescence property of the complex has also been investigated to understand its emission behaviour. Image 1 • A tetradentate m -phenylenediamine based ligand yields a dinuclear copper complex. • The strain involved during coordination introduces a distorted tetrahedral geometry. • UV-visible spectral titrations indicate a 1:1 binding ratio for Cu2+ and H 2 L. • · DFT/TD-DFT calculations demonstrate the stability of the binuclear copper complex. [ABSTRACT FROM AUTHOR]