Direct reaction of thiazolidine‐2‐thione (tzdtH), an anti‐thyroidal agent with diiodine in a molar ratio of 1:2 caused the heterolytic cleavage of diiodine and formation of [{(tzdtH)2I+}·I3−·2I2] (1), whereas the reaction of benzothiazole‐2‐thione (bztzdtH) with diiodine in a molar ratio of 1:2 and 1:1 resulted in the formation of the [{(bztzdtH)I2}·I2] (2) and [(bztzdtH)I2] (3) charge‐transfer (c.t.) complexes. In addition, the reaction between benzimidazole‐2‐thione (bzimtH) with diiodine in a molar ratio 1:2 yielded the c.t. complex [{(bzimtH)I2}2·I2·2H2O] (4). All reactions were carried out in dichloromethane. The molecules have been characterized by m.p., elemental analyses, and FT‐Raman, FT‐IR, UV/Vis and 1H NMR spectroscopy. Crystal structures of the named complexes have been determined by X‐ray diffraction at −103 °C (1), 20 °C (2 and 3) and −168 °C (4). The charge‐transfer nature of the bonds of the adducts (1−4) has been verified by the lengthening of the I−I bond lengths as compared to the S−I bond lengths, by the characteristic c.t. bands observed in the UV spectra and by the shifts of frequencies measured for the I−I bond vibration in the FT‐Raman spectra of the complexes. Compound 1 (C3H5NS2I4) is monoclinic with a space group P21/n and a = 9.145(2) Å, b = 13.259(2) Å, c = 10.615(2) Å, β = 106.30(2)°, Z = 4. The complex is ionic, containing an S−I+−S linkage and an I3− counter anion. Compound 2 [C7H5NS2I4, monoclinic, space group P21/n, a = 8.357(2) Å, b = 17.829(4) Å, c = 9.603(2) Å, Z = 4, β = 94.39(3)°] consists of a benzothiazole‐2‐thione ligand bonded with an iodine atom through a sulfur atom. A neutral diiodine molecule is also co‐crystallized. A benzothiazole‐2‐thione ligand is also bonded through its sulfur atom to an iodine atom in molecule 3 [C7H5NS2I2, orthorhombic, space group P212121, a = 4.189(1) Å, b = 9.770(3) Å, c = 27.704(8) Å, Z = 4]. Extended intramolecular N−H···I contacts link the molecules forming a supramolecular assembly. The crystal structure of 4 (C7H6N2SI3·H2O) reveals a monoclinic space group P21/c and a = 13.4828(14) Å, b = 4.6704(4) Å, c = 21.267(2) Å, β = 101.029(8)°, Z = 4. It consists of a benzimidazole‐2‐thione ligand bonded to an iodine atom through a sulfur atom. An extended intramolecular linkage via I(2)···H(4)[C(4)] leads to the formation of dimers, while an extended hydrogen‐bonding network {H(12w)[O(12)w]···N(3), O(1w)···N(3)} links the alternate parallel dimers forming a supramolecular assembly. Attempts to draw conclusions on the behavior of a thione, when used as an anti‐thyroidal agent, towards diiodine have been made. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

New and more aggressive antibiotic resistant bacteria arise at an alarming rate and represent an ever-growing challenge to global health care systems. Consequently, the development of new antimicrobial agents is required to overcome the inefficiency of conventional antibiotics and bypass treatment limitations related to these pathologies. In this study, we present a synthesis protocol, which was able to entrap tetracycline antibiotic into silica nanospheres. Bactericidal efficacy of these structures was tested against bacteria that were susceptible and resistant to antibiotics. For nonresistant bacteria, our composite had bactericidal efficiency comparable to that of free-tetracycline. On the other hand, the synthesized composites were able to avoid bacterial growth of resistant bacteria while free-tetracycline has shown no significant bactericidal effect. Finally, we have investigated the cytotoxicity of these nanoparticles against mammalian cells to check any possible poisoning effect. It was found that these nanospheres are not apoptosis-inducers and only a reduction on the cell replication rate was seen when compared to the control without nanoparticles.

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Rh(0) nanoparticles (ca. 4 nm) dispersed in an ionic liquid (1-n-butyl-3-methylimidazolium tetrafluoroborate) were immobilized within a silica network, prepared by the sol-gel method. The effect of the sol-gel catalyst (acid or base) on the encapsulated ionic liquid and Rh(0) content, on the silica morphology and texture, and on the catalyst alkene hydrogenation activity was investigated. The Rh(0) content in the resulting xerogels (ca. 0.1 wt% Rh/SiO(2)) was shown to be independent of the sol-gel process. However, acidic conditions afforded higher contents of encapsulated ionic liquid and xerogels with larger pore diameters, which in turn might be responsible for the higher catalyst activity in hydrogenation of the alkenes.

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The Z r surface loading from Cp2ZrC1, toluene solutions on different kinds of cornmer-cia1 silicas (Grace 948, 952 and 956) was determined by Rutherford backscattering spectrometry. In all silicas, a saturation trend was observed with increasing amount of metal in the initial solution, the largest Zr loading value (1 wt.-%) being observed for silica Grace 948. Solid surface areas were determined by the BET method before and after metallocene immobilization, revealing that the values do not change after zirconocene impregnation. Two different kinds of cocatalyst were used, methylaluminoxane and trimethylaluminium. The aluminium loading on silica Grace 948 was determined using the 27Al(p,y)28Si nuclear reaction and titrometry, both showing that methylaluminoxane leads to an 'A1 grafting' four times more efficient than does trimethylaluminium. Finally, the catalytic activity of these systems was tested in the polymerization of ethylene. The supported catalysts were shown to be active, specially using the low cost trimethylaluminium as a cocatalyst. The polymers obtained with the supported systems exhibited a higher molecular weight than those obtained with the homogeneous system.