Gelson Manzoni de Oliveira

Synthesis and characterization of the first [Q] + [PhTeX 4 ] ¿ complex salt (Q=2-Br¿C 5 NH 5 ; Ph=C 6 H 5 ; X=Br, I) exhibiting a polymeric chain structure

Abstract The reaction of diphenylditelluride with 2-bromopyridine in hydrobromide or hydroiodide acid affords the tetrahalophenyltellurate(IV) [2-Br–C5NH5][PhTeX4] (X=Br and I). The structures of the two salts were characterised by single crystal X-ray diffractometry. The anionic units show a square pyramidal geometry about the tellurium atoms with the phenyl rings in the apical positions. Secondary, interanionic Te⋯X bonds as well as cation–anion H–X interactions hold the moieties in polymeric chains with an octahedral configuration about each tellurium center along the crystal lattice.

Crystal and molecular structure of (α-naphthyl)TeI3

(α-Naphthyl-Te) 2 reacts with iodine in toluene to give deep brown crystals of (α-naphthyl)TeI 3 . The structure of the new organotellurium trihalide has been studied by means of single crystal X-ray diffractometry. (α-Naphthyl)TeI 3 crystallizes in the monoclinic space group P 2 1 / c . The primary coordination sphere about the Te atom is bisphenoidal. The secondary bonds among the heavy atoms hold the (α-naphthyl)TeI 3 molecules into chains along the lattice; the TeI primary bonds show additionally different lengths. The compound can be considered as a supramolecular array comprised of tectonic charge-transfer complexes.

Evaluation of antimycobacterial activity of a sulphonamide derivative

Mycobacterial infections including Mycobacterium tuberculosis have been increasing globally. The additional prevalence of multidrug-resistant (MDR-TB) strains and extensively drug-resistant tuberculosis (XDR-TB) stimulate an urgent need for the development of new drugs for the treatment of mycobacterial infections. It is very important to test the antimicrobial activity of novel compounds because they can be used in new with antimycobacterial drug formulation. Studies have shown that Mycobacterium smegmatis can be used in Minimum Inhibitory Concentration (MIC) assays with the advantage of rapidly and safely screen anti-tubercular compounds. This paper presents an evaluation of potential mycobacteriological compounds derived from inorganic synthesis and their microbiological performance along and in conjunction with Trimethoprim. Antimicrobial activity experiments were carried out by using the microdilution technique in broth to evaluate the sensibility against M. smegmatis. MIC values were between 0.153 and 4.88 μg/ml for the compounds tested. Tests of interaction between drugs were made by the method of Fractional Inhibitory Concentration Index (FICI). The compound [Au (sulfatiazolato)(PPh3)] showed synergism FICI = 0.037 and was evaluated by isobols.

Synthesis, crystal structure, and optical characteristics of [Pd2Hg4Cl6{Te(DMB)}6]·2DMF, [HgClTe(DMB)]4, and the ring-forming cluster [Pd12(TePh)24]·2DMF

The clusters here discussed represent improvements to our preparative techniques directed toward the synthesis of ternary nanoclusters of the type MM′Te. Hg(TeR)2 (R = (2,6-OCH3)2C6H3) reacts with PdCl2 to give [Pd2Hg4Cl6{(TeR)}6]·2DMF (1) and [HgClTeR]4 (2), and further with Pd(O2CCH3)2 to give [Pd12(TePh)24]·2DMF (3). The core of compound 1 was analysed by first principles DFT and the results confirm the existence of two systems 3c–4e−, in which the two TeII atoms act as bridging ligands. While compound 2 appears to provide the driving force for the formation of cluster 1. In the case of metallocycle 3, the driving force guiding the reaction probably originates from the mercury salts (HgCl2 or Hg(Ac)2) formed during the process.

One step substitution of NO and Cl by a metal-S-C-N-ring in CpCr(NO)2Cl: synthesis and molecular structure of CpCr(NO)‘DMPYS’ (Cp=π-C5H5; DMPYS=4,6-dimethyl-pyrimidine-2-thiolato)

Abstract CpCr(NO)2Cl reacts in THF under reflux with the Na salt of 4,6-dimethyl-pyrimidin-2-thiol to give CpCr(NO)(DMPYS)·1/4 toluene (Cp=π-C5H5; DMPYS=4,6-dimethylpyrimidine-2-thiolato) and NaCl. The ligand substitution in CpCr(NO)2Cl probably occurs over displacement of NO followed by Cl− elimination. CpCr(NO)‘DMPYS’ crystallizes in the triclinic space group P 1 , formally with 25% of a toluene solvate molecule for each CpCr(NO)(DMPYS)-unity. In the new complex, the chromium atom shows a ‘tetrahedral’ coordination geometry derived from the octahedral structural principle, with a four members ring formed by the metal atom and the fragment SCN of the ligand.

Synthesis, X-ray structural features, DFT calculations and fluorescence studies of a new pyridoxal-benzimidazole ligand and its respective molybdenum complex

Pyridoxal hydrochloride reacts with 1,2-phenylenediamine to give 4-(1H-benzimidazol-2-yl)-5-(hydroxymethyl)-2-methylpyridin-3-ol hydrochloride (BIMIPY, 1). The reaction of 1 with bis(acetylacetonato)-dioxidomolybdenum(VI) leads to the formation of the complex [(MoO2)2(H2O)2(μ-O)(BIMIPY–H+)2]·4DMSO·2H2O (2). In the binuclear complex the metal centers attain a distorted octahedral geometry; a water molecule coordinates to each Mo atom and two imidazolic ligands chelate two MoO2+2 ions. The sixth coordination position in complex 2 is accomplished by a μ-oxido ligand, with an inversion center, which connects two moieties of [(MoO2)(H2O)(BIMIPY–H+)] to a dinuclear species. Secondary, intermolecular hydrogen bonds support the growth of the supramolecular assembly of the Mo complex. Mechanisms for the formation of the functionalized benzimidazole ligand are also proposed and discussed. First principles DFT calculations of reactivity indexes are used to investigate a possible mechanism leading from the benzimidazole to a dimeric complex involving (MoO2+2) molecules and an oxido bridge ligand. Further, the expected fluorescence of the complex is absent, due to decomposition of the complex in solution. On the other hand, an experimental investigation of the photophysical properties of the ligand shows that it is fluorescent. Time dependent density functional theory calculations are performed to characterize the absorption and fluorescence spectra of the ligand.

Identification of antimicrobial activity among new sulfonamide metal complexes for combating rapidly growing mycobacteria

Mycobacteriosis is a type of infection caused by rapidly growing mycobacteria (RGM), which can vary from localized illness, such as skin disease, to disseminated disease. Amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem and sulfamethoxazole are antimicrobial drugs chosen to treat such illnesses; however, not all patients obtain the cure. The reason why the treatment does not work for those patients is related to the fact that some clinical strains present resistance to the existing antimicrobial drugs; thereby, the research of new therapeutic approaches is extremely relevant. The coordination of antimicrobial drugs to metals is a promising alternative in the development of effective compounds against resistant microorganisms. Sulfonamides complexed with Au, Cd, Ag, Cu, and Hg have shown excellent activity against a variety of microorganisms. Considering the importance of fighting against infections associated with RGM, the objective of this study is to evaluate the antimycobacterial activity of metal complexes of sulfonamides against RGM. Complexed sulfonamides activity were individually tested and in association with trimethoprim. The minimum inhibitory concentration (MIC) and time-kill curve of compounds against the standard strains of RGM [Mycobacterium abscessus (ATCC 19977), Mycobacterium fortuitum (ATCC 6841) and Mycobacterium massiliense (ATCC 48898)] was determined. The interaction of sulfonamides with trimethoprim was defined by inhibitory concentration index fractional for each association. The results showed that sulfonamides complexed whit metals have outstanding antimicrobial activity when compared to free sulfamethoxazole, bactericidal activity and synergistic effect when combined with trimethoprim.

A centrosymmetric polymorph of chloridotris(triphenylphosphine-κP)copper(I) at 150 K

This study characterizes a new polymorph of the title compound, [CuCl(C18H15P)3], and analyses the influence of the extensive network of weak hydrogen-bonding interactions in the generation of this different crystal structure. The compound crystallizes in the centrosymmetric space group C2/c with two crystallographically independent molecules per asymmetric unit, in contrast with the previously determined polymorph which crystallizes in the noncentrosymmetric space group P3 with three crystallographically independent molecules in the asymmetric unit, each with crystallographically imposed C3 symmetry [Gill, Mayerle, Welcker, Lewis, Ucko, Barton, Stowens & Lippard (1976). Inorg. Chem. 15, 1155-1168]. The geometries of the two molecules of the title compound are very similar, with each having an approximately tetrahedral coordination around the central Cu atom and approximate C(s) molecular symmetry. The molecules pack in chains parallel to the crystallographic b axis, connected by C-H...Cl and C-H...pi(phenyl) hydrogen bonds.

Supramolecular self-assembling of [HgII(RC6H4NNNC6H4R)2Py] [R = EtOC(O)] through reciprocal metal-η2-arene π-interactions and non classical C-H···O bonding: synthesis and X-ray characterization of a bis diaryl symmetric-substituted triazenide complex polymer of Hg(II)

Deprotonated 1,3-bis(4-ethoxycarbonylphenyl)triazene reacts with Hg(CH3COO)2 in tetrahydrofurane to give light-yellow crystals of {[HgII(RC6H4NNNC6H4R)2Py]2}n [R = EtOC(O)]. The [HgII(RC6H4NNNC6H4R)2Py] tectons are linked to pairs as centrosymmetric dimers through reciprocal metal-η2-arene π-interactions. The dimeric units - related to each other by a n-glide plane - are linked into chains along to the crystallographic direction [101] through non classical C-H···(O)COEt (hydrogen) bonds involving the ortho C-H group of the pyridine ligand. These chains are related by translation in the unit cell along the direction [100] through another kind of non classical hydrogen bonding, this one involving hydrogen and oxygen atoms of adjacent ethoxycarbonylphenyl groups of the same plane, resulting an extended supramolecular bidimensional (2D) assembling parallel to the crystallographic plane (011).

Synthesis and structural characterization of fac-BrMn(CO)3{PH(C6H5)2}2

In attempts to find appropriated methods for preparation of unstable sulfinyl and sulfonylphosphane complexes we have synthesized the diphenylphosphine complexes of Mn(I), BrMn(CO)4PHPh2, (1) and BrMn(CO)3(PHPh2)2(2). Both should undergo electrophilic substitution in the presence of an adequated base. Parallel to the reactions of stabilization of phosphanes we have studied by means of x-ray analysis the structure of fac-BrMn(CO)3(PHPh2)2(2). The compound crystallizes in the triclinic space group Pī, a = 9.840(2), b = 11.207(2), c = 13.083(3) Å, α = 72.00(3), β = 69.59(3), γ = 81.41(3)°, U = 1284.7(4) Å3, and Z = 2. In this complex the manganese atom shows an octahedral coordination geometry, with three carbonyl ligands in a fac arrangement, and one bromide and two diphenylphosphine ligands cis to each other.