Homoleptic Cyclic Trinuclear d10 Complexes: From Self-Association via Metallophilic and Excimeric Bonding to the Breakage Thereof via Oxidative Addition, Dative Bonding, Quadrupolar and Heterometal Bonding Interactions

Trinuclear coinage metal metallacycles are obtained when two-coordinate metals are bonded to C, N or N, N anionic ligands of the proper symmetry to form cycles where metals alternate with bridging ligands. Cyclotrimers often exhibit semiplanar structures and mostly columnar or finite stacking in the solid state by means of metallophilic interactions. They show some peculiar properties with an impact on many different fields such as supramolecular architectures, luminescence, molecular recognition, host-guest chemistry, and acid-base chemistry. The comprehensive evaluation of the data shows that, depending on the nature of the central metal and bridging ligand, there is a fine balance of the energy involved in the inter-trimer bond cleavages and the energy gained from the formation of new intermolecular electrostatic interactions, proceeding occasionally to the chemical extreme of redox processes. In this review, a number of important developments are highlighted and systematically analyzed along with structural and computational data and chemical properties to rationalize and build a unifying leitmotif for this chemistry; the focus is made on the authors’ contributions in these areas

Self-initiation of antiretroviral therapy in the developing world: the involvement of private pharmacies in an HIV program

Self-initiation to antiretroviral treatment (ART) exposes the patient to the risk of drug toxicity, poor adherence to treatment, and escalates the development of drug resistance. To determine the sources of antiretroviral (ARV) drugs by unregistered human immunodeficiency virus (HIV)-infected patients and the extent of ARV self-medication. Simulated clients were used to investigate availability and ARV dispensing practice in the private pharmacies in Dar Es Salaam, Tanzania. A total of 480 HIV-infected patients qualifying to start ART were interviewed to find out their previous use of ARV drugs prior to visiting the HIV clinics. Venous blood (2 mL) was collected from each patient who indicated not to have used ARVs in the past (n = 450). Blood samples were analyzed for the presence and levels of nevirapine (NVP). Only 5.1% (23/451) of pharmacies were found stocking ARVs drugs, among which 4.0% were retail. Drug dispensers in nearly all (15/18) retail pharmacies which stocked ARVs were willing to sell ARVs without prescription. Out of 450 enrolled patients, only 2.7% (12) stated that they had been receiving ARV drugs from HIV clinics but interrupted the ART treatment due to various reasons. From 450 patients, only 10% had quantifiable NVP concentrations in the blood, despite stating in an interview that they had not recently used ARVs. Prior use of ARV drugs outside HIV clinics was rare among patients attending those centers. However, the results show that some patients could access and use ARV drugs from private pharmacies without undergoing ART eligibility assessment in HIV clinics

Insights into Molecular Structures and Optical Properties of Stacked [Au-3(RN=CR ')(3)](n) Complexes

The molecular structure of stacked cyclic trinuclear gold(I) complexes [Au-3(RN=CR'(3)](n), with n = 1-4, where R = H, methyl (Me), cyclopentyl ((c)Pe), and phenyl (Ph) and R' = OH and methoxy (OMe) were studied computationally at the second-order Moller-Plesset (MP2) and density functional theory (DFT) levels of theory. At the DFT level, the aurophilic and dispersion interactions were accounted for by using the TPSS functional in combination with the semiempirical D3 correction. The structure optimizations yielded the lowest energy for a slided stacked structure of the [Au-3(HN=COH)(3)](2) dimer, where monomers are slightly shifted relative to one another. At the MP2 level, the slided structure is 32 kJ/mol more stable than the staggered dimer structure, which in turn is energetically 11 kJ/mol below the eclipsed structure. The calculations show that aromatic ligands lead to a planar and prismatic structure of [Au-3(PhN=COMe)(3)](4), whereas for [Au-3('PeN=COMe)(3)](4), a chair conformation is obtained due to steric effects. Excitation energies were calculated for [Au-3(RN=CR')(3)] and [Au-3(RN=CR'(3)](2) with R = H, Me, and 'Pe and R' = OH and OMe at the time-dependent DFT level using the optimized molecular structures of the singlet ground state. To simulate the luminescence spectra, the lowest triplet excitation energy was also calculated for the molecular structure of the lowest triplet state. The calculated excitation energies of [Au-3(HN=COH)(3)] and [Au-3(HN=COH)(3)](2) are compared with values obtained at the approximate singles and doubles coupled cluster (CC2) and the second-order algebraic diagrammatic construction (ADC(2)) levels of theory. The calculated absorption and emission energies reproduce the experimental trends, with extremely large Stokes shifts. A solvoluminescence mechanism is also proposed.Peer reviewe

Characterization of In Vivo Keratin 19 Phosphorylation on Tyrosine-391

Keratin polypeptide 19 (K19) is a type I intermediate filament protein that is expressed in stratified and simple-type epithelia. Although K19 is known to be phosphorylated on tyrosine residue(s), conclusive site-specific characterization of these residue(s) and identification potential kinases that may be involved has not been reported.In this study, biochemical, molecular and immunological approaches were undertaken in order to identify and characterize K19 tyrosine phosphorylation. Upon treatment with pervanadate, a tyrosine phosphatase inhibitor, human K19 (hK19) was phosphorylated on tyrosine 391, located in the 'tail' domain of the protein. K19 Y391 phosphorylation was confirmed using site-directed mutagenesis and cell transfection coupled with the generation of a K19 phospho (p)-Y391-specific rabbit antibody. The antibody also recognized mouse phospho-K19 (K19 pY394). This tyrosine residue is not phosphorylated under basal conditions, but becomes phosphorylated in the presence of Src kinase in vitro and in cells expressing constitutively-active Src. Pervanadate treatment in vivo resulted in phosphorylation of K19 Y394 and Y391 in colonic epithelial cells of non-transgenic mice and hK19-overexpressing mice, respectively.Human K19 tyrosine 391 is phosphorylated, potentially by Src kinase, and is the first well-defined tyrosine phosphorylation site of any keratin protein. The lack of detection of K19 pY391 in the absence of tyrosine phosphatase inhibition suggests that its phosphorylation is highly dynamic

Coinage metals trinuclear metallocycles: old and new aspects of this class of compounds

Coinage metals trinuclear metallocycles: old and new aspects of this class of compounds Galassi R. a, Oumarou C. S. a, Omary A. M. b, Nesterov V. b, Burini A.a aSchool of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino; e-mail: [email protected] b Department of Chemistry, University of North Texas, Denton, 1155 Union Circle, TX 76203, USA; e-mail: [email protected] Azoles such as imidazoles and pyrazoles are optimal bridging ligands to obtain C,N or N,N trinuclear coinage metals metallocycles. Since past decade till now, few worldwide research groups including us have focused their attention to their synthesis and characterization.[1] Moreover, the photophysical properties[2] the extended network of metallophilic bondings in the supramolecular structure and the pi-acid/pi-base chemistry[3] of these compounds directed the research to theoretical studies bringing to a better interpretation of the experimental behaviors.[4] Here we report the synthesis of new coinage metals metallocycles and their spectroscopic characterizations highlighting points of continuity with the previous analogs and new features for new perspective research lines. As in example, the 1-vinylimidazole resembles the acid-base chemistry of the 1-benzylimidazole gold(I) metallocycle, while substitution in position 4,5 of 1-benzylimidazole with electron-withdrawing group, do not allow the formation of metallocycles with the same synthethic route and mononuclear gold(I) derivatives have been obtained. The nature of the heterocycle and of the substituents, in addition to their position in the azolate ligand defines and tunes the properties of the final products. References: 1) Galassi, R.; Burini, A.; Omary-Rawanashed, M., Omary, M. A., Comm. Inorg. Chem. 2014, in submission. 2) Rawashdeh-Omary, M. A.; Omary, M. A.; Fackler Jr, J. P, Galassi R., Pietroni, B. R.; Burini, A. J. Am. Chem. Soc 2001, 123; 9689-9691. 3) Burini, A.;. Fackler Jr, J. P; Galassi R., Grant, T. A.. Omary, M. A; Rawashdeh-Omary, M. A.; Pietroni, B. R.; Staples R. J. J. Am. Chem. Soc., 2000; 11264-11265. 4) Galassi, R.; Ricci, S.; Burini, A.; Macchioni, A; Marmottini, F.; Tekarli, S. M.; Nesterov, N.V.; Omary, M. A. Inorg. Chem. 2013, 52, 14124-14137

4-(2-Methoxyphenyl)piperazin-1-ium 6-chloro-5-isopropyl-2,4-dioxopyrimidin-1-ide

In the cation of the title salt, C11H17N2O+.C7H8ClN2O2 -, the piperazine ring adopts a distorted chair conformation and contains a positively charged N atom with quaternary character. Its mean plane makes a dihedral angle of 42.36 (8)� with the phenyl ring of its 2-methoxyphenyl substituent. The 2,4-dioxopyrimidin-1-ide anion is generated by deprotonation of the N atom at the 1-position of the pyrimidinedione ring. Intramolecular C—H...O hydrogen bonds generate S(6) ring motifs in both the cation and the anion. In the crystal, N—H...O, N—H...N and C—H...O hydrogen bonds are also observed, resulting in a twodimensional network parallel to the ab plane. The crystal stability is further consolidated by weak C—H...n interactions