Reactivity difference between protolytic forms of some macrocyclic chromium(III) complexes in ligand substitution and electron transfer processes

The review provides insight into the mechanism of ligand substitution and electron transfer (from chromium( III) to iron(III)) by comparison of the reactivity of some tetraazamacrocyclic chromium(III) complexes in the conjugate acid-base forms. Use of two geometrical isomers made possible to estimate the influence of geometry and protolytic reactions in trans and cis position towards the leaving group on the rate enhancement. Studies on the reaction rates in different media demonstrated the role played by outer sphere interactions in a monodentate ligand substitution

Facile cobalt(III) template synthesis of novel branched hexadentate polyamine monocarboxylates

New hexadentate polyamine monocarboxylate ligands, 11-amino-9-(2- aminoethyl)-3,6,9-triazaundecanoate (tren-engly-), 12-amino-10-(2-aminoethyl)-3,7,10-triazadodecanoate (tren-tngly-) and 13-amino-11 (2-aminoethyl)-3,8,11-triazatridecanoate (tren-bngly-), were synthesized by intramolecular coupling of tetradentate tris(2-aminoethyl) amine (tren) and didentate N-(ω-formylalkyl)glycinates, OCH(CH 2)n,NHCH2CO2-, in easily and stereoselectively assembled cobalt(III) templates, p-[Co(tren){(RO) 2CH(CH2)nNHCH2CO2}] (O3SCF3)2, n= 1-3 (R = Me or Et). The reaction sequences comprised assembly of the template from [Co(tren)(O 3SCF3)2]O3SCF3 (1) and (RO)2CH(CH2)nNHCH2CO2Et, deprotection of the pendant acetal in acid, intramolecular condensation of the resulting aldehyde with a coordinated primary amine at intermediate pH to form the inline and reduction of this by NaBH4. For n = 1, imine formation occurred exclusively at the primary amine trans to the carboxylate producing the hexadentate 11-amino-9-(2-aminoethyl)-3,6,9-triazaundeca-5-enoato (tren-enimgly-) complex, i-[Co(trenenimgly)]Cl2̇3. 5H2O. In all instances, subsequent imine reduction gave the s isomer complex, exclusively. Complexes p-[Co(tren){(MeO)2CHCH 2gly}](O3SCF3)2 (3), i-[Co(tren-enimgly)]ZnCl4̇H2O (5), s-[Co(tren-engly)]ZnCl4 (s-6), s-[Co(tren-tngly)]ZnCl 4̇H2O (s-7) and s-[Co(tren-bngly)ZnCl 3]2ZnCl4 (s-8) were structurally characterized by X-ray crystallography. Charcoal-catalyzed equilibration of s-[Co(tren-engly)]Cl2̇2H2O dissolved in water produced the s- (s-6), p- (p-6) and t-[Co(tren-engly)]2+ (t-6) isomers in comparable amounts, p-6 and t-6 were also structurally characterized as their tetrachlorozincate and chloride salts, respectively. In base-catalyzed reactions, s-6 and t-6 each also formed p-6. Reduction of s-[Co(tren-engly)] Cl2̇2H2O with (NH4)2S and acidification liberated the pentaamino carboxylic acid ligand which was isolated as the hydrochloride salt

The Role, Use and Activation of Strong and Weak Network Ties: A Qualitative Analysis

A characteristic of studies seeking to explain the structure and operation of networks is the use of Granovetter's strong and weak tie hypothesis. Whilst this hypothesis has become an established paradigm, questions and disagreements arise over its applicability at demonstrating the real use and value of each tie. This study extends the work of Granovetter. Using a qualitative ethnographic approach to explore in-depth the networking activities of fourteen respondents, it aims to enhance understanding about the role of ties, how they are used and activated for business activity. Findings demonstrate that it is strong ties that are instrumental for business activity and used extensively to provide knowledge and information but also to maintain, extend and enhance business and personal reputations. Unless activities require their reactivation and manifestation, strong ties remain latent and dormant within the network. Strong ties also provide the mechanism to invoke 'weak' ties, represented by nodes operating in a wider social context. Copyright Blackwell Publishing Ltd 2005.

Ten golden rules for optimal antibiotic use in hospital settings : the WARNING call to action

Abstract: Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or "golden rules," for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice