Repositioning of Disulfiram in Association with Vancomycin Against Enterococcus spp. MDR and XDR.

The identification of molecules that exhibit potent antibacterial activity and are capable of circumventing resistance mechanisms is an unmet need. The repositioning of approved drugs is considered an advantageous alternative in this case, and has gained prominence. In addition, drug synergism can reduce morbidity and mortality in the treatment of nosocomial infections caused by multi-drug resistant microorganisms (MDR). Whole cell growth inhibition assays were used to define the in vitro antibacterial activity of disulfiram against two standard American Type Culture Collection (ATCC) strains and 35 clinical isolates of vancomycin-resistant enterococci (VRE). The ability of disulfiram to synergize with vancomycin was determined by fractional inhibitory concentration index, preceded by the checkerboard test. The cytotoxicity of drugs alone and in combination was tested against Raw 264.7 cells. Disulfiram exhibited potent antibacterial activity against VRE (MIC 16-64 µg mL-1). Results: Associated with vancomycin, disulfiram it had a reduction in MIC of up to 64 times, with values of 0.5-4 µg mL-1. Vancomycin had a MIC of 128-1024 µg mL-1; combined, reduced this value by up to 124 times (8 µg mL-1), with synergy occurring against all strains. Disulfiram and vancomycin alone and in combination did not show cytotoxicity against the eukaryotic cell line. Based on these results, we suggest that the redirection of disulfiram may be promising in the treatment of infections caused by VRE, since it was able to potentiate the activity of vancomycin against the strains, being able to act as an adjuvant in cases of serious infections caused by Enterococcus.

Assessment of the biological potential of diaryltriazene-derived triazene compounds.

In the present study, novel, 1,3-diaryltriazene-derived triazene compounds were synthesized and tested. Triazenes are versatile and belong to a group of alkylating agents with interesting physicochemical properties and proven biological activities. This study describes the synthesis, molecular and crystalline structure, biological activity evaluation, and antifungal and antimicrobial potentials of 1,3-bis(X-methoxy-Y-nitrophenyl)triazenes [X = 2 and 5; Y = 4 and 5]. The antimicrobial and antifungal activities of the compounds were tested by evaluating the sensitivity of bacteria (American Type Culture Collection, ATCC) and clinical isolates to their solutions using standardized microbiological assays, cytotoxicity evaluation, and ecotoxicity tests. The antimicrobial potentials of triazenes were determined according to their minimum inhibitory concentrations (MICs); these compounds were active against gram-positive and gram-negative bacteria, with low MIC values. The most surprising result was obtained for T3 having the effective MIC of 9.937 µg/mL and antifungal activity against Candida albicans ATCC 90028, C. parapsilosis ATCC 22019, and C. tropicallis IC. To the best of our knowledge, this study is the first to report promising activities of triazene compounds against yeast and filamentous fungi. The results showed the potential utility of triazenes as agents affecting selected resistant bacterial and fungal strains.

Assessment of different methods for the detection of biofilm production in coagulase-negative staphylococci isolated from blood cultures of newborns.

INTRODUCTION: Coagulase-negative staphylococci (CoNS) are a frequent cause of bacteremia, especially in neonates. The major virulence determinant in CoNS is the ability to produce biofilms, which is conferred by the icaADBC genes. This study aimed to assess different methods for the detection of biofilm formation in 176 CoNS isolates from blood cultures of newborns. METHODS: The presence of the icaACD genes was assessed by polymerase chain reaction (PCR), and biofilm formation was assessed on congo red agar (CRA), by the tube method (TM), and on tissue culture plates (TCP). RESULTS: Of the 176 CoNS isolates, 30.1% expressed icaACD and 11.4% expressed icaAD. The CRA assay and TM showed that 42% and 38.6% of the isolates were biofilm producing, respectively. On TCP, 40.9% of the isolates produced biofilms; 21% were weakly adherent and 19.9% were strongly adherent. When compared to the gold standard technique (PCR), the CRAassay showed 79% sensitivity and 84% specificity (kappa = 0.64), TM showed 78% sensitivity and 89% specificity (kappa = 0.68), and TCP showed 99% sensitivity and 100% specificity (kappa = 0.99). CONCLUSIONS: In this study, ~42% of CoNS isolates produced biofilms, and the presence of icaACD was associated with a greater capacity to form biofilms. Compared to the other phenotypic methodologies, TCP is an ideal procedure for routine laboratory use.

Assessment of different methods for the detection of biofilm production in coagulase-negative staphylococci isolated from blood cultures of newborns

Abstract INTRODUCTION: Coagulase-negative staphylococci (CoNS) are a frequent cause of bacteremia, especially in neonates. The major virulence determinant in CoNS is the ability to produce biofilms, which is conferred by the icaADBC genes. This study aimed to assess different methods for the detection of biofilm formation in 176 CoNS isolates from blood cultures of newborns. METHODS: The presence of the icaACD genes was assessed by polymerase chain reaction (PCR), and biofilm formation was assessed on congo red agar (CRA), by the tube method (TM), and on tissue culture plates (TCP). RESULTS: Of the 176 CoNS isolates, 30.1% expressed icaACD and 11.4% expressed icaAD. The CRA assay and TM showed that 42% and 38.6% of the isolates were biofilm producing, respectively. On TCP, 40.9% of the isolates produced biofilms; 21% were weakly adherent and 19.9% were strongly adherent. When compared to the gold standard technique (PCR), the CRAassay showed 79% sensitivity and 84% specificity (kappa = 0.64), TM showed 78% sensitivity and 89% specificity (kappa = 0.68), and TCP showed 99% sensitivity and 100% specificity (kappa = 0.99). CONCLUSIONS: In this study, ~42% of CoNS isolates produced biofilms, and the presence of icaACD was associated with a greater capacity to form biofilms. Compared to the other phenotypic methodologies, TCP is an ideal procedure for routine laboratory use.

Supramolecular Packing of a Series of N-Phenylamides and the Role of NH···O=C Interactions.

A series of seven N-phenylamides [R-C(O)NHPh, in which R: CH3, C(CH3)3, Ph, CF3, CCl3, CBr3, and H] were used as models in this study. Molecular packing and intermolecular interactions were evaluated by theoretical calculations, solution NMR, and quantum theory of atoms in molecules analyses. Crystallization mechanisms were proposed based on the energetic and topological parameters using the supramolecular cluster as demarcation. Concentration-dependent 1H NMR experiments corroborated the proposed interactions between molecules. For all compounds (except for R: H, which initially formed tetramers), layers (two-dimensional) or chains (one-dimensional) were formed in the first stage of the proposed crystallization mechanisms. The presence of strong intermolecular NH···O=C interactions promoted the first stages. The study in solution provided different values of association constant (K ass) governed by the hydrogen bond NH···O=C, showing that the stronger interactions are directly influenced by the substituent steric hindrance. A correlation between K ass(NH···O=C) from the solution and the NH···O=C interaction energy in the crystal showed a good trend.

Insights on the Similarity of Supramolecular Structures in Organic Crystals Using Quantitative Indexes.

The quest for concepts of isostructurality in organic crystals has been long and mostly based on geometric data, even with the development of modern software. This field of study is of great interest to the pharmaceutical industry and for the prediction of crystal structures. Despite this, there is still no methodology that provides broad quantitative and comparable similarity data between two complete crystalline structures. The present study demonstrated that the similarity between two crystalline structures could be estimated from the similarity between the two "supramolecular clusters". Quantitative indexes for similarity comparisons of crystal structures were shown using nine 5-aryl-1-(1,1-dimethylethyl)-1H-pyrazoles as a model. This proposal includes the quantitative data of a geometric parameter (I D), a contact area parameter (I C), and an energetic parameter (I G). The proposed indexes exhibited good perspective regarding the similarity data and distinct regions of similarity. The range of similarity was set at I X ≥ 0.80, 0.80 > I X > 0.60, and I X ≤ 0.60 (X = D, C, or G). Indexes with a value near 1.0 indicate systems with isostructural, isocontact, and isoenergetic behavior. The results indicated that supramolecular structures with high similarity must have high values for all three indexes (I D, I C, and I G).

Synergistic antibacterial effect of statins with the complex {[1-(4-bromophenyl)-3-phenyltriazene N 3 -oxide-κ 2 N 1,O 4 ](dimethylbenzylamine-κ 2 C 1, N 4 )palladium(II)}

Abstract The treatment of infections caused by resistant microorganisms represents a big challenge in healthcare due to limited treatment options. For this reason, the discovery of new active substances which are able to perform innovative and selective actions is of great impact nowadays. Statins and triazenes (TZC) have consolidated as a promising class of compounds, characterized by the expressive biological activity, especially antimicrobial activities. The aim of this study was to assess the in vitro synergistic antibacterial effect of the association of statins and a new TZC complex {[1-(4-bromophenyl)-3-phenyltriazene N 3-oxide-κ 2 N 1,O 4](dimethylbenzylamine-κ 2 C 1,N 4)palladium(II)} (Pd(DMBA)LBr) against American Type Culture Collection (ATCC) strains and clinical isolates. The complex and the statins showed bacterial activity of all tested strains and clinical isolates, evidencing that TZC complexion with metals can be promising. Simvastatin showed synergy when associated to the complex (FICI≤0.5), being the minimum inhibitory concentration (MIC) of 16 µg mL-1 found in 6 samples. Thus, it is possible to infer that the association between Pd(DMBA)LBr and simvastatin consists of an alternative to increase the pontential of these compounds, since statins have low toxicity.

Synthesis, Crystal Structure, and Supramolecular Understanding of 1,3,5-Tris(1-phenyl-1H-pyrazol-5-yl)benzenes.

Understanding the supramolecular environment of crystal structures is necessary to facilitate designing molecules with desirable properties. A series of 12 novel 1,3,5-tris(1-phenyl-1H-pyrazol-5-yl)benzenes was used to assess the existence of planar stacking columns in supramolecular structures of pyrazoles. This class of molecules with different substituents may assist in understanding how small structural changes affect the supramolecular environment. The obtained compounds did not present the formation of planar stacking interactions between benzenes in solid or liquid states. This supposition was indicated by single crystal diffraction, Density Functional Theory (DFT) and quantum theory of atoms in molecules (QTAIM) calculations, and concentration-dependent liquid-state ¹H nuclear magnetic resonance (NMR). NMR showed that chemical shifts of benzene and pyrazole hydrogens confirm that planar stacking interactions are not formed in solution. The crystalline structures presented different molecular conformations. The molecular structures of 5 and 9b are in a twisted conformation, while compound 7 showed a conformation analogous to a calyx form.

Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile.

INTRODUCTION:: In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile. METHODS:: One hundred and seventy-eight CREs were isolated at a university hospital in south Brazil in a one-year period. Samples were assessed using disk diffusion tests with inhibitors of ß-lactamases such as phenylboronic acid (AFB), cloxacillin (CLOXA), and ethylenediaminetetraacetic acid (EDTA). Strains with differences in zone diameters ≥ 5mm for disks supplemented or not were considered producers of carbapenemases. RESULTS:: Klebsiella pneumoniae was the most prevalent CRE, which appeared in 80.3% cases (n = 143). Among clinical materials, the rectal swab was responsible for 43.4% of the isolations (n = 62), followed by urine (18.9%; n = 27). Among the CREs identified in this study, the growth of 56.7% (n = 101) isolates, which were putative producers of Klebsiella pneumoniae carbapenemase (KPC), were inhibited by AFB, whereas 7.3% (n = 13) isolates were inhibited by both AFB and CLOXA and were considered as putative producers of plasmid-mediated AmpC; approximately 3.4% (n = 6) were inhibited by EDTA, which possibly produced metallo-ß-lactamase. Lastly, 32.6% (n = 58) cases showed negative results for AFB, CLOXA, and EDTA sensitivity, and represented another class of ß-lactamases and/or mechanism of resistance. CONCLUSIONS:: Phenotypic screening of CREs is important for clinical laboratories that monitor outbreaks of resistant microbes. Phenotypic tests that use carbapenemase inhibitors and enhancers such as AFB, CLOXA, and EDTA are necessary since they are good screening methods for the detection of carbapenemases.

Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

Abstract INTRODUCTION: In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile. METHODS: One hundred and seventy-eight CREs were isolated at a university hospital in south Brazil in a one-year period. Samples were assessed using disk diffusion tests with inhibitors of β-lactamases such as phenylboronic acid (AFB), cloxacillin (CLOXA), and ethylenediaminetetraacetic acid (EDTA). Strains with differences in zone diameters ≥ 5mm for disks supplemented or not were considered producers of carbapenemases. RESULTS: Klebsiella pneumoniae was the most prevalent CRE, which appeared in 80.3% cases (n = 143). Among clinical materials, the rectal swab was responsible for 43.4% of the isolations (n = 62), followed by urine (18.9%; n = 27). Among the CREs identified in this study, the growth of 56.7% (n = 101) isolates, which were putative producers of Klebsiella pneumoniae carbapenemase (KPC), were inhibited by AFB, whereas 7.3% (n = 13) isolates were inhibited by both AFB and CLOXA and were considered as putative producers of plasmid-mediated AmpC; approximately 3.4% (n = 6) were inhibited by EDTA, which possibly produced metallo-β-lactamase. Lastly, 32.6% (n = 58) cases showed negative results for AFB, CLOXA, and EDTA sensitivity, and represented another class of β-lactamases and/or mechanism of resistance. CONCLUSIONS: Phenotypic screening of CREs is important for clinical laboratories that monitor outbreaks of resistant microbes. Phenotypic tests that use carbapenemase inhibitors and enhancers such as AFB, CLOXA, and EDTA are necessary since they are good screening methods for the detection of carbapenemases.

Synthesis, characterization and biological activity of a gold(I) triazenide complex against chronic myeloid leukemia cells and biofilm producing microorganisms

ABSTRACT The enhancement of anti-leukemia therapy and the treatment of infections caused by multidrug-resistant pathogens are major challenges in healthcare. Although a large arsenal of drugs is available, many of these become ineffective, and as a result, the discovery of new active substances occurs. Notably, triazenes (TZCs) have been consolidated as a promising class of compounds, characterized by significant biological activity, especially antiproliferative and antimicrobial properties. The aim of this study is the synthesis and characterization of a new triazenide complex of gold (I), as well as the in vitro assessment of its antiproliferative activity against the K562 cell line (Chronic Myeloid Leukemia), and antibacterial activity against bacterial isolates of biofilm-producing coagulase-negative staphylococci. The combination of TZC with gold metal tends to have a synergistic effect against all biofilm-producing isolates, with Minimum Inhibitory Concentration values (MIC) between 32 and 64 µg mL-1. It has also shown activity against K562 cell line, getting an IC50=4.96 µM. Imatinib mesylate (Glivec) was used as reference, with IC50=3.86 µM. To the best of our knowledge, this study represents the first report of the activity of a TZC complexed with gold ion in the oxidation state (I) against microorganisms that produce biofilm and K562 cells.

Atividade antibacteriana de um composto triazenido com ouro frente a cepas bacterianas e isolados clínicos / Actividad antibacteriana de un triazenido compuesto de oro frente a las cepas bacterianas y los aislados clínicos / Antibacterial activity of gold complexed triazenid against bacterial strains and clinical isolates

Introdução: de uma forma alarmante, estudos demonstraram que nos últimos anos ocorreu um grande aumento na resistência bacteriana frente aos antibióticos. Consequentemente, há uma grande necessidade de descoberta de novas substâncias ativas, e entre essas, os compostos triazenos vêm demonstrado-se como uma classe promissora de metalofármacos, com significativa atividade antimicrobiana. Além do mais, a associação do radical farmacofórico triazenos com metais, como o ouro, favorece a produção de moléculas com maior atividade biológica. Objetivo: avaliar a atividade antibacteriana in vitro do composto triazenos inédito complexado com ouro no estado de oxidação I {(1-(2-bromofenil)-3-(2-nitrofenil)triazenido(trifenilfosfina)ouro(I)}, frente a cepas bacterianas padrões de referência American Type Culture Collection e isolados clínicos com resistência múltipla as drogas (MDR). Métodos: a atividade antibacteriana do composto triazenos foi determinada através do método de Concentração Inibitória Mínima, baseado no Clinical and Laboratory Standards Institute de 2012. A CIM foi caracterizada visualmente, como a menor concentração que inibiu completamente o crescimento dos microrganismos nos poços de diluição. Resultados: o composto em estudo apresentou pronunciada atividade antibacteriana, sendo ativo em 43,4 por cento (10/23) das bactérias testadas, mostrando-se seletivo frente a cepas Gram positivas. Conclusão: o complexo triazenos apresentou estreito espectro de ação, sendo ativo somente frente aos microrganismos classificados como Gram positivos, demonstrando assim uma alternativa para a concepção de uma nova classe de metalofármacos com atividade antibacteriana(AU)

Introducción: de una manera alarmante, los estudios han demostrado que en los últimos años hubo un gran aumento de la resistencia bacteriana a los antibióticos. Por consiguiente, hay una gran necesidad para el descubrimiento de nuevas sustancias activas, y entre estas, los compuestos triazenos se muestran como una clase prometedora de metalofármacos con actividad antimicrobiana significativa. Por otra parte, la asociación de triazeno farmacóforo radical con metales como el oro favorece la producción de moléculas con actividad biológica superior. Objetivo: evaluar la actividad antibacteriana in vitro del compuesto sin precedentes triazeno complejado con oro en el estado de oxidación I {(1-(2-bromofenil)-3-(2-nitrofenil)triazenido(trifenilfosfina)ouro(I)}, frente a las cepas de las normas bacterianas, cepas de referencia American Type Culture Collection y los aislados clínicos con resistencia múltiple a los medicamentos. Métodos: la actividad antibacteriana del triazeno compuesto se determinó por el método de la concentración inhibitoria mínima, sobre la base de estándares clínicos y de laboratorio de 2012. Este método se caracteriza visualmente como la menor concentración que inhibió completamente el crecimiento de microorganismos en los pocillos de dilución. Resultados: el compuesto de ensayo mostró actividad antibacteriana pronunciada, el cual fue activo en 43,4 por ciento (10/23) de las bacterias ensayadas, uy mostró ser selectivo contra las cepas grampositivas. Conclusión: el complejo triazeno mostró estrecho espectro de acción, el cual es activo solo frente a los microorganismos clasificados como grampositivos, lo que demuestra una alternativa para la concepción de una nueva clase de metalofármacos con actividad antibacteriana(AU)

Introduction: several studies have revealed that the increase of bacterial resistance to antibiotic is really alarming in the last few years. Consequently, the discovery of new active substances is a must and the triazene compounds appear as a promising class of metal drugs with significant antimicrobial action. On the other hand, the association of radical pharmacophorous triazene with metals such as gold facilitates the production of greater biological action molecules. Objective: to evaluate the in vitro antibacterial activity of this unprecedented compound called gold complexed with triazene at oxidation state I {(1-(2-bromophenyl)-3-(2-nitrophenyl)triazenide (triphenylphosphane) gold(I)} against the bacterial standard strains, American Type Culture Collection reference strains and the multiple drug resistance clinical isolates. Methods: the antibacterial activity of the compound triazene was estimated by the minimal inhibitory concentration method on the basis of the clinical and laboratory standards 2012. This method is visually characterized as the lowest concentration that fully inhibited the bacterial growth in the dilution wells. Results: the tested compound showed significant antibacterial activity, being active in 43.4 percent (10/23) of tested bacteria and selective for Gram-positive strains. Conclusions: triazene complex showed narrow action spectrum since it is only active against Gram-positive microorganisms, which is in turn an alternative for conception of a new class of metal drugs with antibacterial action(AU)

Film/contact loading method improves the encapsulated amount of triazene anticancer compounds in polymeric micelles.

The development of organic solvent-free methods for the encapsulation of hydrophobic molecules is necessary for advances in micelle-mediated drug delivery. In this study we investigated the film/contact approach in which the use of organic solvents is limited to the preparation of a dry film before encapsulation. Unloaded micelles of five structurally related block copolymers were placed in contact with thin homogeneous films of two hydrophobic triazene anticancer compounds (1-(4-amidophenyl)-3-(4-acetylphenyl)triazene (1) and corresponding triazenido complex with triphenylphosphanegold(I) fragment (2)). The micelle surface becomes saturated with the drug, which eventually penetrates as a front into the core. Because the drug interacts with both the shell and the core microenvironments of micelle during the process, the maximum loading capacities were very sensitive to block copolymer micelle composition, ranging from 2.2 to 20.4% (wt./wt. of polymer). We conclude that micelles with poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) cores are the best option for the encapsulation of triazene compounds because i) they are prepared in absence of organic phase; ii) the drug concentration in the particles is high enough for a therapeutic effect and iii) the responsiveness properties of PDPA is appropriate for practical applications in pH-triggered drug release systems.

Preparation, crystallography and spectroscopic properties of the polymeric {(1-(E)-2-pyridinylmethylidene)semicarbazone)(aqua)copper(II)} sulphate dihydrate complex: evidence of dynamic Jahn-Teller effect.

Pyridine-2-carbaldehyde semicarbazone ligand (HL) reacts with copper(II) sulphate in water solution to yield the coordination polymer [{Cu(II)(HL)(H(2)O)(SO(4))}(n)] (1). The crystals are triclinic with space group P(-1) and the metal ion is occupying a distorted octahedral geometry. EPR results show that a dynamic Jahn-Teller (J-T) effect is operative in water solutions and also support the stability of the polymeric chains as they continue to show a characteristic half-field Δm(S)=±2 transitions. UV-visible spectrum analysis allowed access to the J-T stabilization energy of 5995 cm(-1) in water. Thermogravimetric/differential thermal analysis curves showed a step-by-step decomposition of complex 1 with loss of water, release of SO(3) and oxidation of the semicarbazone ligand in the 30-422°C range.

Antitumor and antimycobacterial activities of cyclopalladated complexes: X-ray structure of [Pd(C2,N-dmba)(Br)(tu)] (dmba=N,N-dimethylbenzylamine, tu=thiourea).

The reactions between [Pd(C(2),N-dmba)(micro-X)](2) (dmba=N,N-dimethylbenzylamine; X=Cl, Br) and thiourea (tu) in the 1:2 molar ratio at room temperature resulted in the mononuclear compounds [Pd(C(2),N-dmba)(Cl)(tu)] (1) and [Pd(C(2),N-dmba)(Br)(tu)] (2), which were characterized by elemental analyses and infrared (IR), (1)H- and (13)C{(1)H} NMR spectroscopies. The crystal and molecular structures of 2 were determined by single-crystal X-ray diffraction. In vitro cytotoxicity assays of the compounds 1, 2, tu, dmba and cisplatin were carried out using two murine tumor cell lines, namely mammary adenocarcinoma (LM3) and lung adenocarcinoma (LP07). The compounds 1, 2, tu and dmba were also tested against Mycobacterium tuberculosis and their MIC values were determined.

Bis(azido) alpha-iminooxime cobalt macrocyclic complex: synthesis, spectroscopy and ZINDO/S calculations.

Herein we report on the macrocyclic complex [Co(dohpn)(N3)2] (dohpn=2,3,9,10-tetramethyl-1,4,8,11-tetraazaundecane-1,3,8,10-tetraen-11-ol-1-olate). According to the MM+ optimized structure, it shows an octahedral environment around the metal ion with an overall planar configuration of the macrocyclic ligand, while azido ligands are not perpendicular to the plane of the macrocycle. Quantum mechanic calculations through semi-empirical methods were performed and a detailed spectroscopic (ZINDO/S) assignment is also presented.

3-(4-Acetylphenyl)-1-(4-nitrophenyl)triazene.

The crystal structure of the title compound, C(14)H(12)N(4)O(3), shows that the stereochemistry about the N=N double bond of the N=N-N(H) moiety is trans. The whole molecule is almost planar (r.m.s. deviation = 0.0654 A), the interplanar angle between the phenyl rings being 0.7 (1) degrees and the largest interplanar angle being that between the phenyl ring and the nitro group of the 4-nitrophenyl substituent [11.5 (2) degrees ]. Intermolecular N-H.O interactions between molecules related by translation give rise to chains along the [110] and [1-10] directions, and these chains are held together by N.O pi-pi interactions. An unequal distribution of the double-bond character among the N atoms suggests a delocalization of pi electrons over the diazoamine group and the adjacent aryl substituents.

cis-Bis[1,3-bis(2-fluorophenyl)triazenido-kappa2N1,N3]bis(pyridine-kappaN)cadmium(II).

In the title compound, [Cd(C12H8F2N3)2(C5H5N)2], the Cd atom lies on a crystallographic twofold axis in space group Iba2. The coordination geometry about the Cd(II) ion corresponds to a rhombically distorted octahedron, with two deprotonated 1,3-bis(2-fluorophenyl)triazenide ions, viz. FC6H4NNNC6H4F-, acting as bidentate ligands (four-electron donors). Two neutral pyridine (py) molecules complete the coordination sphere in positions cis with respect to one another. The triazenide ligand is not planar (r.m.s. deviation = 0.204 A), the dihedral angle between the phenyl rings of the terminal 2-fluorophenyl substituents being 24.6 (1) degrees. The triazenide and pyridine Cd-N distances are 2.3757 (18)/2.3800 (19) and 2.3461 (19) A, respectively. Intermolecular C-H.F interactions generate sheets of molecules in the (010) plane.

Synthesis, crystal structure, and spectroscopic characterization of trans-bis[(mu-1,3-bis(4-pyridyl)propane)(mu-(3-thiopheneacetate-O))(3-thiopheneacetate-O)]dicopper(II), [[Cu2(O2CCH2C4H3S)4mu-(BPP)2]]n: from a dinuclear paddle-wheel copper(II) unit to a 2-D coordination polymer involving monatomic carboxylate bridges.

From the reaction between a dinuclear paddle-wheel carboxylate, namely [Cu2mu-(O2CCH2C4H3S)4] (1), and the flexible ligand 1,3-bis(4-pyridyl)propane (BPP) a neutral 2-D coordination polymer [[Cu2(O2CCH2C4H3S)4mu-(BPP)2]]n (2) was obtained. Compounds 1 and 2 were characterized by means of elemental analysis, thermal analysis (TG/DSC), vibrational spectroscopy, and electron paramagnetic resonance (EPR). The crystal structure of 2 reveals that each Cu(II) is coordinated by two nitrogen atoms from different BPP ligands and two 3-thiopheneacetate groups within a distorted square planar geometry in a trans-[N, N, O, O] arrangement. The BPP ligand adopts a TG conformation bridging two copper centers giving rise to a 1-D sinusoidal polymeric chain along the crystallographic c axis. Adjacent 1-D chains are extended into a 2-D coordination network through pairs of monatomic carboxylate bridges in direction of the b axis. This bridging mode affords centrosymmetric dimeric units Cu2O2, and therefore, the copper ions are involved in a CuN2O2O' chromophore displaying a (4 + 1) square pyramidal coordination in the resultant 2-D polymeric network. The polycrystalline X-band EPR spectrum of 2 at room temperature is characteristic of a triplet state with nonnegligible zero-field splitting in agreement with the crystal structure. Crystal data for 2: monoclinic, space group P2(1)/c, a = 9.4253(10) A, b = 10.9373(10) A, c = 23.6378(10) A, beta = 98.733(4) degrees, Z = 2.

[1,3-Bis(4-nitrophenyl)triazenido](triphenylphosphine)gold(I).

In the title complex, [Au(C(12)H(8)N(5)O(4))(C(18)H(15)P)], the coordination geometry about the Au(I) ion is linear, with one deprotonated 1,3-bis(4-nitrophenyl)triazenide ion, [O(2)NC(6)H(4)N=N-NC(6)H(4)NO(2)](-), acting as a monodentate ligand (two-electron donor), and one neutral triphenylphosphine molecule completing the metal coordination. The triazenide ligand is almost planar (r.m.s. deviation = 0.0767 A), with the largest interplanar angle being 11.6 (7) degrees between the phenyl ring of one of the terminal 4-nitrophenyl substituents and the plane defined by the N=N-N triad. The Au-N and Au-P distances are 2.108 (5) and 2.2524 (13) A, respectively. Pairs of molecules generated by centrosymmetry are associated into a supramolecular array via intermolecular C-H...O interactions, and N...C and N...O pi-pi interactions.