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Gold(iii) complexes are garnering increasing interest for opto-electronic, therapeutic and catalytic applications., Gold(iii) complexes are garnering increasing interest for opto-electronic, therapeutic and catalytic applications. But so far, very little is known about the factors controlling their reactivity and the very influence of the ancillary ligand. This article reports the first comprehensive study on this topic. The reactivity of a cationic (N,C) gold(iii) complex, namely 1A, towards ethylene has been thoroughly studied and compared with that of the related (P,C) complex 1C. A cationic gold(iii) complex 5A resulting from double insertion of ethylene was selectively obtained. Complex 5A was found to be remarkably stable. It was trapped with chloride and fully characterized. In marked contrast to that observed with 1C, no β-H elimination or linear-to-branched rearrangement of the alkyl chain occurred with 1A. The energy profile for the reactions of 1A with ethylene has been comprehensively investigated computationally, and the influence of the ancillary ligand has been precisely delineated. Because nitrogen is a weaker donor than carbon (and phosphorus), the (N,C) ligand is very electronically dissymmetric, much more than the (P,C) ligand. This makes the two reactive sites at gold quite different, which noticeably influences the competition between migratory insertion and β-H elimination, and actually changes the outcome of the olefin insertion at gold. This study provides valuable insight into the influence of ancillary ligands on gold(iii) reactivity, something critical to further develop Au(iii) and Au(i)/Au(iii) catalysis.

Productivity of tropical lowland moist forests is often limited by availability and functional allocation of phosphorus (P) that drives competition among tree species and becomes a key factor in determining forestall community diversity. We used non-target(31)P-NMR metabolic profiling to study the foliar P-metabolism of trees of a French Guiana rainforest. The objective was to test the hypotheses that P-use is species-specific, and that species diversity relates to species P-use and concentrations of P-containing compounds, including inorganic phosphates, orthophosphate monoesters and diesters, phosphonates and organic polyphosphates. We found that tree species explained the 59% of variance in(31)P-NMR metabolite profiling of leaves. A principal component analysis showed that tree species were separated along PC 1 and PC 2 of detected P-containing compounds, which represented a continuum going from high concentrations of metabolites related to non-active P and P-storage, low total P concentrations and high N:P ratios, to high concentrations of P-containing metabolites related to energy and anabolic metabolism, high total P concentrations and low N:P ratios. These results highlight the species-specific use of P and the existence of species-specific P-use niches that are driven by the distinct species-specific position in a continuum in the P-allocation from P-storage compounds to P-containing molecules related to energy and anabolic metabolism.

Au(iii)-aryl species have been crystallographically isolated as reactive intermediates in oxidant-free C–O and C–N cross coupling processes, using aromatic and aliphatic alcohols and amines, as well as water and amides, as nucleophiles., Au(iii)-aryl species have been unequivocally identified as reactive intermediates in oxidant-free C–O and C–N cross coupling catalysis. The crystal structures of cyclometalated neutral and cationic Au(iii) species are described and their key role in 2 electron-redox Au(i)/Au(iii) catalysis in C–O and C–N cross couplings is shown. Nucleophiles compatible with Au-catalyzed cross couplings include aromatic and aliphatic alcohols and amines, as well as water and amides.

Pyruvate-dependent aldolases exhibit a stringent selectivity for pyruvate, limiting their synthetic potential application, a drawback shared with other existing aldolases. Structure-guided rational protein engineering rendered a 2-keto-3-deoxy-L-rhamnonate aldolase variant, fused with maltose binding protein (MBP-YfaU W23V/L216A), capable to efficiently convert larger pyruvate analogs, e.g. having linear and branched aliphatic chains, in aldol addition reactions. Combination of these nucleophiles with N-Cbz-alaninal and N-Cbz-prolinal electrophiles gave access to chiral building blocks, e.g. derivatives of (2S,3S,4R)-4-amino-3-hydroxy-2-methylpentanoic acid (68%, dr 90:10) and the enantiomer of Dolaproine (33%, dr 94:6) as well as a collection of unprecedented α-amino acid derivatives of the proline and pyrrolizidine type, with conversions varying between 6-93% and diasteromeric ratios from 50:50 to 95:5 depending on the nucleophilic and electrophilic components, This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 635595 (CarbaZymes), the Ministerio de Economía y Competitividad (MINECO), the Fondo Europeo de Desarrollo Regional (FEDER) (grant no. CTQ2015-63563-R to P.C. and CTQ2015-64436-P to T.P.), and COST action CM1303 Systems Biocatalysis.

This work describes the employment of discrete “AgCF3” complexes as efficient transmetalating agents to PdIIto surmount overlooked challenges related to the transmetalation step in Pd- catalyzed trifluoromethylation processes. We report the participation of a unique silver ate (Cs)[Ag(CF3)2] complex, under stoichiometric and catalytic conditions, in the unprecedented one-pot formation of PhCF3 using PhI as starting material. Moreover, we show that the transmetalation step, which is often ignored in these transformations, can also determine the success or failure of the coupling process.

Póster presentado en BIOTRANS 2015, celebrado del 26 al 30 de julio de 2015 en Viena (Austria), Intramolecular stereoselective carboligations are important reactions in organic synthetic chemistry essential for the access of natural occurring compounds and analogues. Besides the chemical methodologies, a plethora of intramolecular C-C bond forming reactions exists in different metabolic pathways of living organism catalyzed by highly evolved enzymes. Examples of carboligases such as of aldolases or ThDP depending enzymes performing asymmetric intramolecular aldol reactions with synthetic substrates are scarce in the literature. In this work, we endeavored to investigate on the intramolecular C-C bond formation via benzoin reaction catalyzed by benzaldehyde lyase from Pseudomonas fluorescens biovar I (BAL). We investigate BAL-catalyzed intramolecular benzoin reaction on benzaldehyde moieties substrates connected with a spacer derivative via ether linkage (i.e. 2,2'- (1), 3,3’ (2) and 4,4’ (3)-(n-alkane-1,n-diylbis(oxy))dibenzaldehyde derivatives). The reaction performance comparing the intra and inter benzoin reaction with substrates 1-3 as well as their analogues with symmetric and unsymmetrical aromatic substitutions was investigated. The results obtained of substrate conversion, stereochemical outcome of the enzymatic reactions and molecular models that intended to explain the reactivity of the different substrates will be reported.

New chromophore-quencher rhenium(I) tricarbonyls, of formulae [Re(4,4’-X2-bpy)(CO)3(PCA)]+, [(4,4’-X2-bpy)(CO)3Re(μ-PCA)Re(CO)3(4,4’-X2-bpy)]2+, and [(4,4’-X2-bpy)(CO)3ReI-(μ-PCA)-RuII(NH3)5]3+, with X = Ph or CO2Me and PCA = 4-pyridinealdazine, have been synthesized as PF6- salts andcharacterized by spectroscopic, electrochemical and photophysical techniques. Contrasting to previously reported species with X = Me or H, these complexes emit at room temperature in CH3CN. The recovery of luminescence can thus be ascribed to the change of energy levels induced by adding electron-withdrawing substituents to the 2,2´-bipyridine ring, since the emissive ReII(X2bpy-) excited state becomes much lower in energy than ReII(PCA-) non-emissive excited state. For the mononuclear and the symmetric dinuclear rhenium(I) complexes with X = CO2Me in aqueous solutions, consecutive protonation of both pyridinic and imine N atoms of PCA cause unusual bell-shaped curves of both the absorption and the emission intensities vs. pH, because of opposite effects on the electronic delocalization of PCA. Therefore, the latter property can be employed to devise novel luminescent sensors of acidity of the on-off-on type. The corresponding unsymmetric dinuclear complexes, of formula [(4,4’-X2-bpy)(CO)3ReI(μ- PCA)RuIII(NH3)5]4+, were obtained in situ by oxidizing the [ReI,RuII] precursors in CH3CN solution; from spectral and electrochemical measurements, the values of the metal-to-metal electronic coupling elements have been determined. Fil: Cattaneo, Mauricio. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Fagalde, Florencia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Katz, Néstor Eduardo. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Borsarelli, Claudio Darío. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; Argentina. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; Argentina Fil: Parella, Teodor. Servei de Rmn; España

La plata és avui dia àmpliament utilitzada en catàlisi homogènia per a la síntesi de compostos orgànics a causa del seu caràcter d'àcid de Lewis i el seu poder oxidant. La Ag(I) és un potent oxidant monoelectrònic que troba utilitat en un gran nombre de processos catalítics. Tanmateix, els cicles catalítics de dos electrons, molt comuns en la química organometàl·lica dels metalls nobles, no han estat mai considerats possibles per a la plata. En aquest estudi descrivim un cicle catalític Ag(I)/Ag(III) que és operatiu en una reacció model d'acoblament creuat per a la formació d'enllaços C–O. Espècies aril–Ag(III) han estat inequívocament identificades com a intermedis d'aquest cicle catalític. L'estudi de la síntesi i la reactivitat de l'esmentat complex ha permès per primera vegada la caracterització de les etapes d'addició oxidant i eliminació reductiva de formació d'enllaços carboni–nucleò- fil en centres monometàl·lics de plata. El present treball demostra que els processos d'eliminació reductiva en espècies aril–Ag(III) són efectius en reaccions d'acoblament creuat per a la formació d'enllaços C–O, C–N, C–S, C–C i C–halur, incloses les reaccions de fluoració d'arils. Aquest estudi suposa un punt de partida per a l'expansió de la química redox Ag(I)/Ag(III) a noves metodologies per a la síntesi orgànica, en analogia a la química d'acoblament creuat del coure o el pal·ladi. A més, els resultats descrits proporcionen una comprensió mecanística fonamental única en les reaccions d'acoblament creuat catalitzades per plata i refuten la concepció generalment acceptada que la química redox de la plata només pot provenir de processos d'un sol electró., Silver is extensively used in homogeneous catalysis for organic synthesis owing to its Lewis acidity and unique high oxidation power. The high oxidation potential of Ag(I) makes it a powerful one-electron oxidant that finds utility in a large number catalytic processes. However, two-electron redox catalytic cycles, most common in noble metal organometallic reactivity, have never been considered. Herein we show that an Ag(I)/Ag(III) catalytic cycle is operative in a model C–O cross-coupling reaction. Aryl–Ag(III) species have been unequivocally identified as an intermediate in the catalytic cycle. The study of the synthesis and reactivity of this complex has enabled for the first time the direct characterization of aryl halide oxidative addition and carbon–nucleophile bond-forming reductive elimination steps at monometallic silver centers. This report demonstrates that reductive elimination processes at aryl–Ag(III) species are effective for C–O, C–N, C–S, C–C and C–halide coupling reactions, including aryl fluorination. We anticipate our study as the starting point for expanding Ag(I)/Ag(III) redox chemistry into new methodologies for organic synthesis, resembling well-known copper or palladium cross-coupling catalysis. Furthermore, findings described herein provide a unique fundamental mechanistic understanding of Ag-catalyzed cross-coupling reactions and dismiss the generally accepted conception that silver redox chemistry can only arise from one-electron processes.

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Table S1. One-way ANOVAs of identified metabolites in leaf organ and epispheric. Table S2 One-way ANOVAs of identified metabolites in flowers organ and epispheric. Table S3 One-way ANOVAs of identified metabolites in in leaf organ in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S4 One-way ANOVAs of identified metabolites in identified in leaf epispheric in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S5 One-way ANOVAs of identified metabolites in in flowers organ in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S6 One-way ANOVAs of identified metabolites in in flowers epispheric in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S7 Abbreviation, family and the real name of the metabolites detected. (PDF 3529 kb)

Table S1. One-way ANOVAs of identified metabolites in leaf organ and epispheric. Table S2 One-way ANOVAs of identified metabolites in flowers organ and epispheric. Table S3 One-way ANOVAs of identified metabolites in in leaf organ in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S4 One-way ANOVAs of identified metabolites in identified in leaf epispheric in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S5 One-way ANOVAs of identified metabolites in in flowers organ in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S6 One-way ANOVAs of identified metabolites in in flowers epispheric in different antibiotic treatment within the plants receiving control levels of water in leaf. Table S7 Abbreviation, family and the real name of the metabolites detected. (PDF 3529 kb)

A novel series of complexes of the formula [Ru(4,4′-X2-bpy)2(Mebpy-CN)](PF6)2 (X = −CH3, −OCH3, −N(CH3)2; Mebpy-CN = 4-methyl-2,2′-bipyridine-4′-carbonitrile) have been synthesized and characterized by spectroscopic, electrochemical, and photophysical techniques. Inclusion of the electron-withdrawing substituent −CN at one bpy ligand and different electrondonor groups −X at the 4,4′-positions of the other two bpy ligands produce a fine tuning of physicochemical properties. Redox potentials, electronic absorption maxima, and emission maxima correlate well with Hammett’s σp parameters of X. Quantum mechanical calculations are consistent with experimental data. All the complexes can be anchored through the nitrile moiety of Mebpy-CN over ZnO nanowires in dye-sensitized solar cells that exhibit an improvement of light to electrical energy conversion efficiency as the electronic asymmetry increases in the series. Fil: Salomón, Fernando Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Vega, Nadia Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Moran Vieyra, Faustino Eduardo. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina Fil: Borsarelli, Claudio Darío. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; Argentina Fil: Longo, Claudia. Universidade Estadual de Campinas; Brasil Fil: Cattaneo, Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina

A novel approach for the fast and efficient structural discrimination of molecules containing multiple stereochemical centers is described. A robust J-resolved HSQC experiment affording highly resolved 1JCH/1TCH splittings along the indirect dimension and homodecoupled 1H signals in the detected dimension is proposed. The experiment enables in situ distinction of both isotropic and anisotropic components of molecules dissolved in compressed PMMA gels, allowing a rapid and direct one-shot determination of accurate residual dipolar coupling constants from a single NMR spectrum. Fil: Castañar, Laura. Universitat Autònoma de Barcelona; España Fil: García, Manuela Emila. University Of Carnegie Mellon; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Hellemann, Erich. University Of Carnegie Mellon; Estados Unidos Fil: Nolis, Pau. Universitat Autònoma de Barcelona; España Fil: Gil, Roberto Ricardo. University Of Carnegie Mellon; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España

Novel mono- and dinuclear tricarbonylrhenium(I) complexes of formula [Re(Mebpy-CN)(CO)3Cl] (1), [Re(Mebpy-CN)(CO)3(CH3CN)](PF6) (2), and [(CH3CN)(CO)3Re(Mebpy-CN)Ru(NH3)5](PF6)3 (3), in which Mebpy-CN = 4-methyl-2,2′-bipyridine-4′-carbonitrile, were prepared and characterized by spectroscopic, photophysical, and computational techniques. The complete structure of complex 2 was determined by X-ray diffraction. The increased conjugation in the bipyridyl ring owing to the nitrile substituent increases the emission quantum yields of the 3MLCT (metal-to-ligand charge-transfer) lowest-lying excited states of 1 and 2 with respect to the corresponding bpy complexes (bpy = 2,2′-bipyridine). The mixed-valent species of formula [(CH3CN)(CO)3Re(Mebpy-CN)Ru(NH3)5]4+ (4) was prepared in situ and as a mixed salt; the charge recombination from its metal-to-metal charge-transfer (MMCT) excited state is predicted to lie in the Marcus inverted region. The electronic structures and optical properties of all the reported complexes calculated by DFT and TD-DFT methods agree reasonably well with experimental results. Fil: Mecchia Ortiz, Juan Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Moran Vieyra, Faustino Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina Fil: Borsarelli, Claudio Darío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina Fil: Romero, Isabel. Universidad de Girona; España Fil: Fontrodona, Xavier. Universidad de Girona; España Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Lis, Noemi Dora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Fagalde, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina

The syntheses of new mononuclear ruthenium(II) complexes of the type: [Ru(bpy)(L)(tpm)](PF6)2 {tpm = tris(1-pyrazolyl)-methane; bpy = 2,2′-bipyridine; L = pz (pyrazine; 1), 4,4′-bpy (4,4′-bipyridine; 2), and bpe [trans-1,2-bis(4-pyridyl)ethylene; 3]} are described, together with their spectroscopic, electrochemical, and photophysical properties. A complete assignment of the NMR resonances of the three species could be made in CD3CN by bidimensional techniques. A fine tuning of the energies of MLCT (metal-to-ligand charge transfer) states in these complexes is disclosed when comparing, in CH3CN, the values of their maximum absorption wave-lengths for the most intense visible bands (λ max) and their redox potentials for the RuIII/Ru II couples; this effect, relevant to the design of efficient photocatalysts, can be attributed to a decreasing order of dπ(Ru) →*(2,2′-bpy) backbonding when decreasing the distance between both N atoms in the aromatic nitrogen heterocycle L that acts in a monodentate manner. Only the species with L = bpe emits at room temperature, pointing to the conclusion that MLCT excited states in this series become higher in energy than dd excited states when the value of λmax is lower than 400 nm. These species are also useful building blocks for new dinuclear mixed-valent complexes. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005. Fil: Katz, Néstor Eduardo. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Romero, Isabel. Universidad de Girona; España Fil: Llobet, Antoni. Universidad de Girona; España Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Benet Buchholz, Jordi. Bayer Industry Services; Alemania

The novel tetradentate ligand 1,4-bis(4-(40-methyl)-2,20-bipyridyl)-2,3-diaza-1,3-butadiene (BBDB) was synthesized and characterized by spectroscopic techniques. New complexes of Re and Ru of formulae: [Re(BBDB)(CO)3(Cl)], [(CH3CN)(CO)3Re(l-BBDB)Re-(CO)3(CH3CN)]2+, [(bpy)2Ru-(l-BBDB)Ru(bpy)2]4+, [(NH3)4Ru(l-BBDB)?Ru(NH3)4]4+ (bpy = 2,20-bipyridine) and complexes of Ru with 4-Me-40-CO2H-bpy (=4-methyl-40-carboxylic acid-2,20-bipyridine) - the hydrolyzed derivative of BBDB- of formulae: [(Ru(4-Me-40-CO2H-bpy)(bpy)2]2+ and [Ru(4-Me-40-CO2H-bpy)(CN)4]2 were prepared and characterized by spectroscopic, electrochemical and computational techniques. The disclosed enhanced electronic coupling in the mixed-valent complex with ruthenium ammines can be explained by the electronic delocalization imposed by the -C=N-N=C- backbone. DFT and TD-DFT calculations can predict the optical properties and electronic structures of the reported complexes and comparisons with calculations performed on previously reported complexes with 4-pyridinaldazine can account for their photophysical behaviour. Fil: Cattaneo, Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Vergara, Monica Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Garcia Posse, Monica E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Fagalde, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Parella, Teodor. Universitat Autonoma de Barcelona; España Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán; Argentina

We report in this work the synthesis and spectroscopic, electrochemical, spectroelectrochemical, and photophysical characterization of a novel series of ruthenium polypyridyl complexes with 4-methyl-2,2′-bipyridine-4′- carbonitrile (Mebpy-CN) as an auxiliary ligand of general formula [Ru(bpy) 3-x(Mebpy-CN)x](PF6)2 (x = 1-3) (with bpy = 2,2′-bipyridine). A significant increase in the lifetime and quantum yield of emission of the lowest 3MLCT excited state is disclosed when going from x = 1 to x = 3, evidencing an improvement of the photosensitizing properties with respect to [Ru(bpy)3](PF 6)2. Furthermore, quenching by molecular oxygen of 3MLCT excited states of the three complexes produced singlet molecular oxygen (1O2) with quantum yield values higher than that of [Ru(bpy)3]2+ in CH3CN. The structure of the complex with x = 1 has been determined by X-ray diffraction. The photoconductivity of ZnO nanowires covered with this same complex is increased by an order of magnitude, pointing to its feasibility as a component of a DSSC. A new dinuclear complex with Mebpy-CN as a bridging ligand has also been prepared and characterized by physicochemical techniques. The derived mixed-valent species of formula [(bpy)2RuII(Mebpy-CN) RuIII(NH3)5]5+ displays a considerable metal-metal electronic coupling due to the delocalization effect of a nitrile group in the 4′ position of the bpy ring. © 2013 American Chemical Society. Fil: Mecchia Ortiz, Juan Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Vega, Nadia Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; Argentina Fil: Comedi, David Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; Argentina Fil: Tirado, Monica Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; Argentina Fil: Romero, Isabel. Universidad de Girona; España Fil: Fontrodona, Xavier. Universidad de Girona; España Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Moran Vieyra, Faustino Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina Fil: Borsarelli, Claudio Darío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina

We report in this work the synthesis and characterization of new mono- and dinuclear complexes of formulas: [Re(bpy)(CO)3(4,4′-azpy)] (CF3SO3), 1 (bpy = 2,2′-bipyridine, 4,4′-azpy = 4,4′-azobis(pyridine)); [(bpy)(CO)3Re(4,4′-azpy) Ru(NH3)5](PF6)3.CH 3CN•6H2O, 2 and the heterodinuclear species [(bpy)(CO)3Re(4,4′-azpy)Ru(NH3)5] 4+, 3 (obtained in situ by electrochemical oxidation of 2). The molecular structure of 1 has been determined by X-ray diffraction. We also report the effect of controlled potential electrolysis, protonation, and light excitation on the absorption and emission properties of these complexes. In particular, complex 1, which is almost non-emissive at room temperature, recovers luminescence either by reduction of coordinated 4,4′-azpy or by trans- to cis-photoisomerization. The detected emission of 1 at 77 K is due to decay from a Re→ bpy metal-to-ligand charge transfer excited state. Time dependent density functional theory calculations support the interpretation of the photophysical changes induced by external stimuli. Fil: Pourrieux, Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Fagalde, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Romero, María Isabel. Universidad de Girona; España Fil: Fontrodona, Xaxier. Universidad de Girona; España Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina

New coordination compounds of formulae: [Ru(trpy)(bpy)(4,4′-azpy)]2+, 1, [Ru(tpm)(bpy)(4,4′-azpy)]2+, 2, [(trpy)(bpy)Ru(4,4′-azpy)Ru(NH3)5]4+, 3, and [(trpy)(bpy)Ru(4,4′-azpy)Ru(bpy)(trpy)]4+, 5, with trpy = 2,2′:6′,2″-terpyridine, tpm = tris(1-pyrazolyl)methane), bpy = 2,2′-bipyridine and 4,4′-azpy = 4,4′-azobis(pyridine), have been synthesized as PF6- salts and characterized by spectroscopic and electrochemical techniques. The structure of the cation [Ru(trpy)(bpy)(4,4′-azpy)]2+ has been determined by X-ray diffraction analysis, which reveals a trans-configuration of coordinated 4,4′-azpy and a packing structure that is based on extensive π-interactions within neighboring molecules. Upon controlled potential electrolysis of the dinuclear [RuII,RuII] complex 3, a stable [RuII, RuIII] mixed-valent species, 4, was detected. From spectral data and Gaussian deconvolution analysis of the intervalence transition in 4, a strong electronic interaction between both ruthenium centers is disclosed (HAB = 550 cm-1), pointing to possible applications of 4,4′-azpy as a conducting bridge in "molecular wires". © 2008 Elsevier Ltd. All rights reserved. Fil: Pourrieux, Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Fagalde, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Benet Buchholz, Jordi. Institut Catala d’Investigacio Quimica; España. Universitat Autònoma de Barcelona; España Fil: Llobet, Antoni. Universitat Autònoma de Barcelona; España

The preparation and characterization by spectroscopic and electrochemical techniques of new dinuclear complexes of the type [(tpm)(bpy)RuII(L)RuII/III(NH3)5]4+/5+ (bpy =2,2'-bipyridine, tpm = tris(1-pyrazolyl)methane, L = pz (pyrazine), 4,4´-bpy (4,4´-bipyridine), BPE (trans-1,2-bis(4-pyridyl)ethylene) and PCA (= 4- pyridinecarboxaldehide azine), are described in this work. The analysis of the visible spectral data for the metal-to-metal charge transfer (MMCT) bands in the corresponding mixed-valent species [RubII,RuaIII] (Rub = Ru bonded to bpy; Rua = Ru bonded to NH3) allows the determination of the reorganization energies l and electronic coupling elements HAB for the intramolecular electron transfers Rub II -Rua III mediated by L. An increased transmission of the metal-to-metal electronic interaction is disclosed for this series, when comparing the distance dependence of HAB to that of the analogous series with trpy (2,2':6',2"-terpyridine) acting as a spectator ligand instead of tpm. Fil: Fagalde, Florencia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: García Posse, Mónica Ema. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Vergara, Monica Mercedes. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Cattaneo, Mauricio. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina Fil: Katz, Néstor Eduardo. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Romero, Isabel. Departament de Química And Serveis Tecnics de Recerca; España Fil: Parella, Teodor. Servei de Rmn; España Fil: Llobet, Antoni. Departament de Química; España

The efficient synthesis of tetrapeptide 5 containing, in alternation, cyclobutane and β-alanine residues is described. NMR experiments both at low temperature in CDCl3 and at 298 K in DMSO-d6 solutions show the contribution of a strong hydrogen bond in the folded major conformation of 5. Temperature coefficients and diffusion times point out a hydrogen bond involving the NH proton from the cyclobutane residue 1 whereas NOEs manifest the high rigidity of the central fragment of the molecule and are compatible with a 14-membered macrocycle. Theoretical calculations predict a most stable folded conformation corresponding to a 14-helix stabilized by a hydrogen bond between NH10 in the first residue and OC25 in the third residue. This structure remains unaltered during the molecular dynamics simulation at 298 K in chloroform. All these results provide evidence for a 14-helical folding and reveal the ability of cis-2-aminocyclobutane carboxylic acid residues to promote folded conformations when incorporated into β-peptides. Fil: Izquierdo, Sandra. Universitat Autònoma de Barcelona; España Fil: Kogan, Marcelo Javier. Institut de Recerca Biomédica; España Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Moglioni, Albertina Gladys. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina Fil: Branchadell, Vicenc. Universitat Autònoma de Barcelona; España Fil: Giralt, Ernest. Institut de Recerca Biomédica; España Fil: Ortuño, Rosa M.. Universitat Autònoma de Barcelona; España

The synthesis and isolation of new RuIIacetonitrile complexes, of general formula trans,fac-[Ru(bpea)(B)(MeCN)](BF4)2 (bpea = N,N-bis(2-pyridylmethyl)ethylamine; B = bpy, 2,2′-bipyridine, 4; B = dppe, 1,2-bis(diphenylphosphino)ethane, 5), together with a synthetic intermediate trans,fac-[Ru(NO3)(bpea)(dppe)](BF4), 6, are described. Ru(bpea)Cl3, 1, is used as the starting material for the synthesis of all complexes 2-6 presented in this paper, which are characterized by analytical, spectroscopic (IR, UV/Vis, 1D and 2D NMR), and electrochemical techniques (cyclic voltammetry). Furthermore, complexes 4, 5, and 6 have also been characterized in the solid state by single crystal X-ray diffraction analysis. Their structures show a distorted octahedral geometry where the bpea ligand binds in a facial mode, the bidentate ligands bpy and dppe bind in a chelate manner, and finally the MeCN or the NO3 - ligand occupy the sixth position of the octahedral Ru metal centre. The kinetics of the basic hydrolysis of the coordinated MeCN ligand for complexes 4 and 5 and for the related complex [Ru(phen)(MeCN)([9]aneS3)](BF4) 2, 7, which contains the 1,4,7-trithiacyclonane ligand ([9]aneS 3) and 1,10-phenanthroline (phen) is also described. Second-order rate constants for acetonitrile hydrolysis measured at 25°C of k = 1.01 10-3 M-1 s-1 for 4, 1.08 10-4 M -1 s-1 for 5, and 6.8 10-3 M-1 s-1 for 7, have been obtained through UV-vis spectroscopy. Activation parameters have also been determined over the temperature range 25.0-45.0°C and agree with a mechanism that involves an associative rate-determining step. Finally the electronic and steric influence of the auxiliary ligands on this reaction for the above and related complexes is discussed. Fil: Mola, Joaquim. Universidad de Girona; España Fil: Pujol, David. Universidad de Girona; España Fil: Rodríguez, Montserrat. Universidad de Girona; España Fil: Romero, Isabel. Universidad de Girona; España Fil: Sala, Xavier. Institut Català d'Investigació Química; España Fil: Katz, Néstor Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentina Fil: Parella, Teodor. Universitat Autònoma de Barcelona; España Fil: Benet Buchholz, Jordi. Institut Català d'Investigació Química; España Fil: Fontrodona, Xavier. Universidad de Girona; España Fil: Llobet, Antoni. Institut Català d'Investigació Química; España