Does the Sign of the Cu–Gd Magnetic Interaction Depend on the Number of Atoms in the Bridge?

Several theoretical investigations with CASSCF methods confirm that the magnetic behavior of Cu–Gd complexes can only be reproduced if the 5d Gd orbitals are included in the active space. These orbitals, expected to be unoccupied, do present a low spin density, which is mainly due to a spin polarization effect. This theory is strengthened by the experimental results reported herein. We demonstrate that Cu–Gd complexes characterized by Cu–Gd interactions through single‐oxygen and three‐atom bridges consisting of oxygen, carbon, and nitrogen atoms, present weak ferromagnetic exchange interactions, whereas complexes with bridges made of two atoms, such as the nitrogen–oxygen oximato bridge, are subject to weak antiferromagnetic exchange interactions. Therefore, a bridge with an odd number of atoms induces a weak ferromagnetic exchange interaction, whereas a bridge with an even number of atoms supports a weak antiferromagnetic exchange interaction, as observed in pure organic compounds and also, as in this case, in metal–organic compounds with an active spin polarization effect.     

Heteronuclear (Co-Ca, Co-Ba) 2,3-pyridinedicarboxylate complexes: synthesis, structure and physico-chemical properties

Three pyridine 2,3-dicarboxylate complexes have been synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray diffractometry. Their magnetic properties have also been studied by EPR and magnetisation measurements. The decomposition of such complexes in air leads to the generation of mixed metal oxides, as confirmed by powder X-ray diffraction.     

Synthesis,characterization, crystal structure and toxicity evaluation of Co (II), Cu (II), Mn (II), Ni (II), Pd (II) and Pt (II) complexes with Schiff base derived from 2-chloro-5-(trifluoromethyl)aniline

A bidentate NO donor Schiff base, 2-(((2-chloro-5- (trifluoromethyl)phenyl)imino)methyl) phenol ( HL ¹ ) and its complexes [Co(L¹)₂(H₂O)₂] ( 1 ), [Cu(L¹)₂] ( 2 ), [Mn(L¹)₂(H₂O)₂] ( 3 ), [Ni(L¹)₂(H₂O)₂] ( 4 ), [Pd₂(L¹)₂(OAc)₂·1.16H₂O] ( 5 ), [Pt(L¹)₂] ( 6 ) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, IR, ¹H-NMR, ¹³C-NMR, UV–Vis, mass spectroscopies and X-ray powder diffraction (XRD). The molecular structures of ligand HL ¹ and two complexes ( 2 and 5 ) were confirmed by X-ray crystallography analysis on the monocrystal. In this complexes, the metal ions are in distorted square-planar environments. The copper (II) complex is mononuclear and crystallized in a monoclinic space group P21/c, whereas palladium (II) complex is dinuclear and crystallized in the trigonal crystal system R-3. The toxicity of the ligand and complexes was evaluated on both plant and animal cells, using the plant species Triticum aestivum L. and the crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the compounds presented very little toxicity on Artemia franciscana Kellogg. Moreover, the palladium (II) complex was devoid of any toxicity on the plant cells.     

Design and synthesis of novel ditopic ligands with a pyrazole ring in the central unit

Research on Chemical Intermediates - Four novel ditopic ligands that have a pyrazole ring in their central unit and are useful for the generation of coordination polymers have been synthesized. Two...     

Chemical modification and characterization of poly(ethylene terephthalate) surfaces for collagen immobilization

The functionalization of poly(ethylene terephthalate) (PET) surface films by reactions with multifunctional amines such as triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) was investigated. For the functionalization of PET films surface we used a new way of treatment, a “sandwich model”. Physical-chemical properties of functionalized PET films were analysed. Qualitative and quantitative determination of the introduced amine groups were examined by means of Fourier Transform Infrared Attenuated Total Reflexion (FTIR — ATR), X-ray photoelectron spectroscopy (XPS), and potentiometric titration. Gained wetting properties were determined by using contact angle measurements and thoroughly analysed by acid-base approach. In addition, surface topography was investigated by atomic force microscopy (AFM). The amount of the introduced amino groups after TETA incorporation has been found to be two times higher as compared to TEPA. Wetting properties were significantly improved after aminolysis. Surface free energy was higher for PET — TETA treated film than that observed for PET — TEPA treated which is in accordance with titration results. The collagen immobilization onto PET treated films was evidenced by using AFM and subsequently by using XPS.      

Fedosov Quantization of Fractional Lagrange Spaces

The main goal of this work is to perform a nonholonomic deformation (Fedosov type) quantization of fractional Lagrange–Finsler geometries. The constructions are provided for a fractional almost K?hler model encoding equivalently all data for fractional Euler–Lagrange equations with Caputo fractional derivative.     

Note on the topological degree of the subdifferential of a lower semi-continuous convex function

The purpose of the present paper is to prove that the topological degree of the subdifferential of a coercive lower semi-continuous function on a sufficiently large ball in a reflexive Banach space is equal to one.

     

EPR study of the low temperature ferroelectric phase transition in Cu doped Rb2ZnCl4 single crystals

Temperature dependent EPR measurements on copper doped Rb₂ZnCl₄ single crystals allowed us to evidence and study the P2₁cn↔C1c1 structural phase transition that takes place in this compound at 74.6 K. From the two types of Cu²⁺ centers localized at different anionic sites, called Cu²⁺(I) and Cu²⁺(II), which are formed in this compound, only the Cu²⁺(II) centers exhibit observable changes in their EPR spectra, attributable to the symmetry lowering. The observed changes have been related to the soft-mode responsible for the structural phase transition.