Zinc(II)-methimazole complexes: synthesis and reactivity

The tetrahedral S-coordinated complex [Zn(MeImHS)(4)](ClO4)(2), synthesised from the reaction of [Zn(ClO4)(2)] with methimazole (1-methyl-3H-imidazole-2-thione, MeImHS), reacts with triethylamine to yield the homoleptic complex [Zn(MeImS)(2)] (MeImS = anion methimazole). ESI-MS and MAS C-13-NMR experiments supported MeImS acting as a (N, S)-chelating ligand. The DFT-optimised structure of [Zn(MeImS)(2)] is also reported and the main bond lengths compared to those of related Zn-methimazole complexes. The complex [Zn(MeImS)(2)] reacts under mild conditions with methyl iodide and separates the novel complex [Zn(MeImSMe)(2)I-2] (MeImSMe = S-methylmethimazole). X-ray diffraction analysis of the complex shows a ZnI2N2 core, with the methyl thioethers uncoordinated to zinc. Conversely, the reaction of [Zn( MeImS)(2)] with hydroiodic acid led to the formation of the complex [Zn(MeImHS)(2)I-2] having a ZnI2S2 core with the neutral methimazole units S-coordinating the metal centre. The Zn-coordinated methimazole can markedly modify the coordination environment when changing from its thione to thionate form and vice versa. The study of the interaction of the drug methimazole with the complex [Zn(MeIm)(4)](2+) (MeIm = 1-methylimidazole) - as a model for Zn-enzymes containing a N-4 donor set from histidine residues shows that methimazole displaces only one of the coordinated MeIm molecules; the formation constant of the mixed complex [Zn(MeIm)(3)(MeImHS)](2+) was determined

Colorimetric response to anions by a "robust" copper(II) complex of a [9]aneN3 pendant arm derivative: CN- and I- selective sensing

The 1 : 1 complex [Cu(L)](BF4)2MeCN (1) of the tetradentate ligand 1-(2-quinolinylmethyl)-1,4,7-triazacyclononane (L) selectively changes its colour in the presence of CN in H2O and MeCN (without undergoing decomplexation from the macrocyclic ligand). The same complex in MeCN assumes different colours in the presence of CN or I

Noise Can Reduce Disorder in Chaotic Dynamics

We evoke the idea of representation of the chaotic attractor by the set of unstable periodic orbits and disclose a novel noise-induced ordering phenomenon. For long unstable periodic orbits forming the strange attractor the weights (or natural measure) is generally highly inhomogeneous over the set, either diminishing or enhancing the contribution of these orbits into system dynamics. We show analytically and numerically a weak noise to reduce this inhomogeneity and, additionally to obvious perturbing impact, make a regularizing influence on the chaotic dynamics. This universal effect is rooted into the nature of deterministic chaos.Comment: 11 pages, 5 figure

Activation of Vitamin D3 in Bovine Mastitis Caused by Streptococcus uberis

Inflamed mammary tissue of three cows infected with Streptococcus uberis was found to have higher concentrations of 1α-hydroxylase than un-inflamed control mammary glands. Increased levels of 1α−hydroxylase resulted in increased production of 1,25-dihydroxyvitamin D3. Therefore, vitamin D3 may have a role in the inflammation and resolution of bovine mastitis

1,25-Dihydroxyvitamin D3 Enhances Bovine Mammary Epithelial Innate Immune Responses

Bovine mammary epithelial cells that were treated with bacterial lipopolysaccharide and 1,25-dihydroxyvitamin D3 showed an increase in the expression of the genes for inducible nitric oxide synthase (iNOS) and S100 calcium binding protein A12 (S100 A12). iNOS and S100 A12 are part of the innate immune response and expressed in the mammary gland during mastitis. Production of 1,25- dihydroxyvitamin D3 in the mammary gland during mastitis, then, may be an important component of the innate immune response

Regulation of Immune Responses to Mycobacteria bovis by a Paracrine Mechanism of Vitamin D Signaling in Cattle

We provide evidence that T-cell responses to Mycobacteria bovis are suppressed by the production of 1,25-dihydroxyvitamin D3 in monocytes and B-cells from cattle. Current vitamin D requirements for cattle are solely based on the classical endocrine mechanism of vitamin D signaling that regulates calcium homeostasis and should be re-evaluated to account for vitamin D signaling mechanisms in the immune system

A structural spproach to the strength evaluation of linear chalcogen bonds

The experimental structural features of chalcogen bonding (ChB) interactions in over 34,000 linear fragments R–Ch⋯A (Ch = S, Se, Te; R = C, N, O, S, Se, Te; A = N, O, S, Se, Te, F, Cl, Br, I) were analyzed. The bond distances dR–Ch and the interaction distances dCh⋯A were investigated, and the functions δR–Ch and δCh⋯A were introduced to compare the structural data of R–Ch⋯A fragments involving different Ch atoms. The functions δR−Ch and δCh⋯A were calculated by normalizing the differences between the relevant bond dR–Ch and ChB interaction dCh⋯A distances with respect to the sum of the relevant covalent (rcovR + rcovCh) and the van der Waals (vdW) radii (rvdWCh + rvdWA), respectively. A systematic comparison is presented, highlighting the role of the chalcogen involved, the role of the R atoms covalently bonded to the Ch, and the role of the A species playing the role of chalcogen bond acceptor. Based on the results obtained, an innovative approach is proposed for the evaluation and categorization of the ChB strength based on structural data

Metal-based gels: Synthesis, properties, and applications

This review covers various aspects of recent developments on the design, the synthesis, the characterization of gels that: (i) are formed in the presence of metal ions (metallogels); (ii) are based on coordination complexes as gelators. Particular attention is devoted to systems that show recognition and sensing properties towards different analytes