Expanding the 2, 2’-bipyrimidine bridged 1D homonuclear coordination polymers family: [MIIbpymCl2] (M=Fe, Co) magnetic and structural characterization

One pot reaction of hydrated chloride salts of Fe(II) and Co(II) with stoichiometric amounts of 2,2’-bipyrimidine (bpym) in a methanol–acetonitrile mixture afforded the corresponding 1D homonuclear coordination polymers, [μ-(bpym)MCl2]n. Crystal structures of both complexes are isomorphous in the highly symmetric orthorhombic space group Fddd. The 1D coordination polymers are composed of almost orthogonal alternating bipyrimidine bridges linking the {MCl2} units. The magnetic behaviour of the Fe(II) compound can be well understood as a uniform S = 2 chain with an antiferromagnetic exchange interaction between metal ion sites. In the case of the Co(II) ion, also an antiferromagnetic interaction is operative along the uniform chain, while at low temperatures a long range-ordering is observed due to spin canting originating from the anisotropic behaviour of the Co(II) lowest energy Kramers doublets.Fil: Alborés, Pablo. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los materiales, medioambiente y energía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rentschler, Eva. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Synthesis and antimicrobial screening of tetra Schiff bases of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene

AbstractIn the present study, novel tetra Schiff bases were synthesized by condensation of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene with different aromatic aldehydes. The chemical structures were confirmed by means of IR, 1H NMR, 13C NMR, and elemental analysis. All compounds were screened for antibacterial (Staphylococcus aureus ATCC-9144, Staphylococcus epidermidis ATCC-155, Micrococcus luteus ATCC-4698, Bacillus cereus ATCC-11778, Escherichia coli ATCC-25922, and Pseudomonas aeruginosa ATCC-2853) and antifungal (Aspergillus niger ATCC-9029 and Aspergillus fumigatus ATCC-46645) activities by paper disc diffusion technique. The minimum inhibitory concentrations (MICs) of the compounds were also determined by agar streak dilution method. Among the synthesized compounds 1,2,4,5-tetra[5-(4-nitrobenzylideneamino)-1,3,4-thiadiazole-2-yl]benzene 7 was found to be the most potent antimicrobial activity with MICs of 3.4, 2.1, 1.2, 2.0, 3.1, 2.4, 1.1, and 1.7μg/mL against the above mentioned respective strains

Nickel(II) complexes based on L-amino-acid-derived ligands: Synthesis, characterization and study of the role of the supramolecular structure in carbon dioxide capture

The formation of the symmetrical 3-carbonate-bridged self-assembled trinuclear NiII complex Na2{[Ni(LO)2(H2O)]3(3-CO3)} (LO is the carboxylate anion of a l-tyrosine derivative), involves atmospheric CO2 uptake. The asymmetric unit of the complex comprises an octahedral coordination for the NiII with two l-tyrosine-based ligands, a water molecule and one O atom of the carbonate bridge. The Ni3–3-CO3 core in this compound is the first reported of this kind according to the Cambridge Structural Database (CSD). The supramolecular structure is mainly sustained by hydrogen bonds developed by the phenolic functionality of the l-tyrosine moiety of one ligand and the carboxylate group of a neighbouring ligand. The crystal packing is then characterized by three interpenetrated supramolecular helices associated with a diastereoisomer of the type RsupP, which is essential for the assembly process. Magnetic susceptibility and magnetization data support weak ferromagnetic exchange interactions within the novel Ni3–3-CO3 core. The NiII complex obtained under the same synthetic conditions but using the analogous ligand derived from the amino acid l-phenylalanine instead of l-tyrosine gives rise to to a mononuclear octahedral system. The results obtained for the different complexes demonstrate the role of the supramolecular structure regarding the CO2 uptake property for these NiII–amino-acid-based systems.Fil: Rivas Marquina, Andrea Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Movilla, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Sanchez Montilva, Olga Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rentschler, Eva. Universidad de Mainz; AlemaniaFil: Carrella, Luca. Universidad de Mainz; AlemaniaFil: Alborés, Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Di Salvo, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentin

Luminescence and light-driven energy and electron transfer from an exceptionally long-lived excited state of a non-innocent chromium(III) complex

Photoactive metal complexes employing Earth-abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non-innocence to tune the luminescence and photochemistry of the excited state of the [CrN6] chromophore [Cr(tpe)2]3+ with close to octahedral symmetry (tpe=1,1,1-tris(pyrid-2-yl)ethane). [Cr(tpe)2]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2]3+ are redox non-innocent, leading to reversible reductive chemistry. The excited state redox potential and lifetime of [Cr(tpe)2]3+ surpass those of the classical photosensitizer [Ru(bpy)3]2+ (bpy=2,2′-bipyridine) enabling energy transfer (to oxygen) and photoredox processes (with azulene and tri(n-butyl)amine)

Jesuit Theologian to Lecture at USD

The 2,2′:6′:2″-terpyridine ligand has literally shaped the coordination chemistry of transition metal complexes in a plethora of fields. Expansion of the ligand bite by amine functionalities between the pyridine units in the tridentate N,N’-dimethyl-N,N’-dipyridine-2-yl-pyridine-2,6-diamine ligand (ddpd) modifies the properties of corresponding transition metal complexes, comprising redox chemistry, molecular dynamics, magnetism and luminescence. The origins of these differences between ddpd and tpy complexes will be elucidated and comprehensively summarized with respect to first row transition metal complexes with d2–d10 electron configurations. Emerging applications of these ddpd complexes complementary to those of the well-known terpyridine ligand will be highlighted

Assessing the reactivity of sodium alkyl-magnesiates towards quinoxaline : single electron transfer (SET) vs. nucleophilic alkylation processes

By exploring the reactivity of sodium butyl-magnesiate (1) supported by the bulky chelating silyl(bisamido) ligand {Ph2Si(NAr*)2}(2-) (Ar* = 2,6-iPr2-C6H3) towards Quinoxaline (Qx), the ability of this bimetallic system to effectively promote SET processes has been disclosed. Thus 1 executes the single-electron reduction of Qx affording complex (2) whose structure in the solid state contains two quinaxolyl radical anions Qx˙ stabilised within a dimeric magnesiate framework. Combining multinuclear NMR and EPR measurements with DFT calculations, new insights into the constitution of 2 in solution and its magnetic behaviour have been gained. Further evidence on the SET reactivity of 1 was found when it was reacted with nitroxyl radical TEMPO which furnished contacted ion pair sodium magnesiate [(Ph2Si(NAr*)2)Mg(TEMPO(-))Na(THF)3] (4) where both metals are connected by an alkoxide bridge, resulting from reduction of TEMPO. The role that the different ligands present in 1 can play in these new SET reactions has also been assessed. Using an amination approach, the Bu group in 1 can be replaced by the more basic amide TMP allowing the isolation of (3) which was characterised by multinuclear NMR and X-ray crystallography. (1)H NMR monitoring of the reaction of 3 with Qx showed its conversion to 2, leaving the hydrogen atoms of the heterocycle untouched. Contrastingly, using sodium homoalkyl magnesiate [NaMg(CH2SiMe3)3] (5) led to the chemoselective C2 alkylation of this heterocycle, suggesting that the presence of the steric stabiliser {Ph2Si(NAr*)2}(2-) on the mixed-metal reagent is required in order to facilitate the Qx reduction