New trinuclear carbonato-bridged copper(II) complexes: Synthesis,crystal structure,and spectroscopic properties

New trinuclear carbonato-bridged copper(II) complexes, [Cu₃(Bipy)₆(μ₃-CO₃)](CF₃SO₃)₄(H₂O)_0.5 (I) and [Cu₃(Phen)₆(μ₃-CO₃)](CF₃SO₃)₄(H₂O)_0.5 (II) (Bipy = 2,2′-bipyridine and Phen = 1,10-phenanthroline), have been synthesized and characterized by X-ray crystallography. In the trinuclear units, a carbonate anion triply bridges three Cu atoms in a μ₃-η¹:η¹:η¹-CO₃ mode. The environment around each copper(II) center is five-coordinate ranging between intermediate to distorted square-pyramidal geometry. In the crystal packing, the molecule of I is involved in a variety of intra/intermolecular non-covalent interactions such as intra/intermolecular stacking and CH···π interactions between the pyridine groups of the chelated ligand, leading to a one-dimensional arrangement of I. In complex II, the molecule is involved in both intra- and intermolecular Phen-Phen π-stacking, forming a three-dimensional network. The spectroscopic (IR, diffuse reflectance, and EPR spectra) properties and the preliminary results of magnetic measurements of both complexes are investigated and compared to other closely related trinuclear copper(II) complexes.     

Crystal structure of bis(2-(2-thiazolylazo)-4-methylphenol)cobalt(III)chloride.

The reaction between CoCl2 x 6H2O and 2-1-(2-thiazolylazo)-p-cresol (TAC) in acetone resulted in six coordinated cobalt(III) complex, [Co(TAC)2]Cl3. Two TAC ligands coordinate with cobalt ion forming four five membered chelate rings. The cobalt ion is octahedrally coordinated by a phenolic oxygen, azo nitrogen and nitrogen in thiazole rings. Three chloride ions are disordered.     

Dinuclear copper(II) complexes with ferromagnetic and antiferromagnetic interactions mediated by a bridging oxalato group: structures and magnetic properties of [Cu2L4(μ-C2O4)](PF6)2(H2O)2 and [Cu2L2(μ-C2O4)(NO3)2((CH3)2NCOH)2] (L = di-2-pyridylamine)

Two dinuclear Cu^II complexes of formula [Cu₂(dpyam)₄(μ-C₂O₄)](PF₆)₂(H₂O)₂ (1) and [Cu₂(dpyam)₂(μ-C₂O₄)(NO₃)₂(DMF)₂] (2) (dpyam=di-2-pyridylamine) have been synthesized and their spectroscopic and magnetic properties characterized. Complex (1) crystallizes in the non-centrosymmetric monoclinic space group Pc, while (2) crystallizes in the non-centrosymmetric triclinic space group P1. Compound (1) involves the compressed octahedral Cu^II environment, whereas (2) exhibits an elongated octahedral Cu^II geometry. Both complexes contain six-coordinate metal centers bridged by planar bis-didentate oxalate group. The geometry, spectroscopic properties and the effective magnetic moment of (1) are very close to those of the recently published [Cu₂(dpyam)₄ (μ-C₂O₄)](ClO₄)₂(H₂O)₃ and [Cu₂(dpyam)₄(μ-C₂O₄)](BF₄)₂(H₂O)₃. Thus (1) is expected to exhibit a very weak ferromagnetic interaction between the Cu^II centers which is confirmed by EPR spectrum. Those of (2) are comparable to those of the recently published [Cu₂(dpyam)₂(μ-C₂O₄)(NO₃)₂(DMSO)₂]. Therefore a strong antiferomagnetic interaction is expected. The effective magnetic moment at room temperature of (1) was measured to be 2.55 BM/dimer, which agrees with the spin only value of Cu^II, 2.45BM calculated for two uncoupled spin=1/2 centers. In (2) the room temperature effective magnetic moment of 2.16 BM/dimer indicates the partial spin paring by antiferromagnetic coupling. This is confirmed by the e.p.r. spectrum and is explained as a result of the magnetic interaction between the coplanar ${\rm d}_{x^2-y^2}$ orbitals on the two copper atoms.     

Aqua­(di‐2‐pyridylamine)oxalato­copper(II) monohydrate

In the structure of the title complex, [Cu(C₂O₄)(C₁₀H₉N₃)(H₂O)]·H₂O, the Cu^II atom displays a square‐pyramidal geometry, being coordinated by two N atoms from the di‐2‐pyridylamine ligand, two O atoms from the oxalate group and one O atom of a water mol­ecule. The complex mol­ecules are linked to form a three‐dimensional supra­molecular array by hydrogen‐bonding inter­actions between coordinated/uncoordinated water mol­ecules and the uncoordinated oxalate O atoms of neighboring mol­ecules.     

Crystal structure of diethoxynitrobenzene-p-tert-butylcalix [4]arene⋅2(CH3)2C=O: Evidence of intra- and intermolecular CH/π interactions forced by crystal packing

Diethoxynitrobenzene-p-tert-butylcalix[4]arene2(CH₃)₂C=O crystallized in the monoclinic system, space group P2₁/c, with cell dimensions a = 16.1437(2) Å, b = 21.0292(2) Å, c = 18.9685(3) Å and = 110.308(1)°. The asymmetric unit consists of a diethoxynitrobenzene-p-tert-butylcalix[4]arene molecule and two solvated acetone molecules. Besides the usual CH/ interaction between p-tert-butylcalix[4]arene cavity and a solvated acetone, this structure shows the intra- and intermolecular CH/ interactions among a nitrobenzene ring, ethylene bridge of the ethoxynitrobenzene side chain and a solvated acetone molecule.     

Diaporthichalasin, a novel CYP3A4 inhibitor from an endophytic Diaporthe sp.

A novel CYP3A4 inhibitor, diaporthichalasin, together with pycnidione were isolated from an endophytic fungus, Diaporthe sp. Their structures were elucidated on the basis of spectral data and the structure of diaporthichalasin was confirmed by X-ray crystallographic analysis. Diaporthichalasin exhibited significantly potent inhibition of CYP3A4 with an IC₅₀ value of 0.626 μM, while the IC₅₀ value of pycnidione was 465 μM.     

Inclusion complexes of β-cyclodextrin with pyrazinamide and piperazine: Crystallographic and theoretical studies

The inclusion complexes of β-cyclodextrin (β-CD) with pyrazinamide (PYA) and piperazine (PIZ) have been investigated both in the solid phase by single-crystal X-ray diffraction analysis and in the gas phase by semi-empirical PM3 calculation. In the crystalline phase, the disordered PYA and PIZ molecules are entirely embedded in the β-CD cavity. The PYA pyrazine-centre displaces upwards by 1.15(1) Å from the β-CD plane, whereas the PIZ centre shifts downwards by 0.76(1) Å from the β-CD plane. The inclusion scenario changed in the gas phase. Two inclusion geometries of the PYA molecule are comparatively stable with binding energies of ? 22.28 and ? 25.29 kJ mol^? 1: the pyrazine centre shifts upwards by 0.5 Å and downwards by 2.0 Å from the β-CD plane. The PIZ molecule positioning at 2.0 Å below the β-CD plane gives a more stable inclusion complex than does the PYA molecule by 22–25 kJ mol^? 1.

Structural distinction of the β-CD–PYA and β-CD–PIZ inclusion complexes in the solid phase (by X-ray crystallography) and gas phase (by PM3 calculation) is a paradigm of the CD conformational flexibility, the induced-fit mechanism and the dynamics of the inclusion process.