Violetta Patroniak

A new polymeric complex of silver(I) with a hybrid pyrazine–bipyridine ligand – synthesis, crystal structure and its photocatalytic activity

The 2,3-bis(6′-methyl-2,2′-bipyridin-6-yl)pyrazine ligand L reacts with trifluoromethanesulfonate silver(I) to give a coordination polymer {[AgL](CF3SO3)}n in which metal ions are in a distorted tetragonal pyramidal coordination geometry. The complex has been characterized by spectroscopic techniques, elemental analysis, X-ray diffraction, and UV-Vis spectroscopy. The methylene blue (MB) degradation was studied using UV-Vis spectrophotometry. After 400 min of exposure to UV light MB was completely decomposed. Degradation of MB after exposure to sunlight was considerably slower: 34% after 400 min and 90% after 133 h. Photodegradation of the dye follows second-order kinetics. {[AgL](CF3SO3)}n is an active photocatalyst for MB degradation under UV-Vis and sunlight irradiation.

Self-assembly of quaterpyridine ligands and Cu + cation into helical complexes of 2:2 stoichiometry under ESI condition

Solutions containing the quaterpyridine ligand 1 and Cu2+ cation were analysed by electrospray ionisation mass spectrometry (ESI-MS). It was found that copper reduction under ESI conditions and self-assembly of 1 and Cu(I) led to the formation of the 2:2 stoichiometry complex. Such stoichiometry is characteristic of the helical complex of a quaterpyridine ligand with Cu(I). The isotope pattern characteristic of the [Cu212]2+ ion, which is different from that of [Cu1]+ ion, is observed. When using methanol as the solvent, only [Cu212]2+ ions are observed in the mass spectrum obtained at low cone voltage. At higher cone voltage, the [Cu212]2+ ion easily dissociates, producing a [Cu1]+ ion. When using other solvents studied, water and acetonitrile, the 2:2 stoichiometry complex is formed, but along with complexes of other stoichiometries. The helical complex was not observed for the silver cation for which only a 1:1 stoichiometry complex was observed (ion [Ag1]+).

New supramolecular dinuclear rare earth Schiff base podates

Abstract The metal-promoted reactions between 2,6-diacetylpyridine and 4-methyl-1,2-phenylenediamine, 3-azaoctane-1,8-diamine (spermidine) or N,N′-bis(2-aminoethyl)-1,3-propanediamine in the presence of lanthanide(III) ions acting as template agents afford new supramolecular dinuclear complexes of podate type with terminal acetylpyridyl groups and N4O2, N5O2 or N6O2 set of donor atoms as a result of [2+1] Schiff base condensation. The complexes were characterized by spectral data (IR, 1 H NMR, FAB-MS), thermogravimetric and elemental analysis.

The template synthesis and characterization of pentaaza macrocyclic complexes of rare earth elements. The crystal structure of the 2,14-dimethyl-3,6,10,13,19-pentaazabicyclo[13.3.1]nonadeca-1(19),2,13,15,17-pentaene-dichlorolutetium(III)perchlorate

Abstract The yttrium and lanthanide ions were found to act as templates for the cyclic [1+1] condensation of 2,6-diacetylpyridine with 3,7-diazanonane-1,9-diamine to yield 16-membered pentadentate Schiff base macrocyclic complexes with an N5 set of donor atoms. The complexes were characterized by spectral data (IR, luminescence, 1H NMR, FAB MS) and elemental analysis. The crystal structure of the lutetium complex was determined by single X-ray analysis providing the first example of the seven-coordination and pentagonal bipyramidal coordination geometry found among the lutetium macrocyclic compounds.

The template synthesis and characterization of alkaline earth metal ion nitrate macroacyclic Schiff base complexes

Abstract The template reaction of 2,6-diacetylpyridine with 1,8-diaminonaphthalene in the presence of calcium(II), strontium(II) and barium(II) nitrates produced the new hexadentate N4O2 open-chain complexes as a result of [2 + 1] Schiff base condensation, irrespective of the molar ratio of starting materials used in the synthesis. They were characterized by IR, UV-vis, 1H NMR and analytical data. No [2 + 2] macrocyclic complexes were isolated, either in the template synthesis, nor on the treatment of the [2 + 1] acyclic complexes with diamine.

Association of quaterpyridine complex cations with polyanionometallates

Reactions in CH3CN:CH2Cl2 (2:1) under Ar of the dimethyl-quaterpyridine ligand C22H18N4 (L) with Mn(ClO4)2, Fe(BF4)2, CoCl2, Co(NO3)2, Zn(NO3)2, Cd(CH3COO)2 and HgCl2 give complexes of the type [ML(H2O) m X n ]2[MX p ], where X denotes the initial counterions, with m = 1, n = 1, p = 4 or m = 2, n = 0, p = 6. The complexes have been characterised by spectroscopic techniques and elemental analysis. The solid-state structures of two forms of the CoCl2 complex have been established by X-ray crystallography, enabling an analysis of the interactions occurring in crystals of this type.

Electrochemical deposition of the new manganese(II) Schiff-base complex on a gold template and its application for dopamine sensing in the presence of interfering biogenic compounds.

Facile and efficient template synthesis of new manganese(II) complex [Mn2(H2L)2](ClO4)2 (1) and its crystal structure are reported. Self-assembly leads to the formation of dinuclear, phenoxo-bridged closed species via exploitation of both binding subunits of the in situ formed new Schiff-base ligand. Gold electrode modified with self-assembled monolayers (SAMs) composed of synthesized complex 1 was applied as a voltammetric sensor for quantitative determination of dopamine (DA) in the presence of ascorbic (AA) and uric acids (UA). The linear relationship between the current response of dopamine at the potential of peak maximum and the concentration was found over a wide analyte concentration range (R(2)≥0.993, 1×10(-10)-8.5×10(-4)M) with a very good sensitivity (4.11Acm(-2)M(-1) at dE/dt=0.1Vs(-1)), high detection limit (6.8×10(-9)M) and excellent reproducibility. It has been proven that current peaks of dopamine, ascorbic and uric acids were clearly separated from each other, thus enabling selective detection of these compounds coexisting in a mixture.

The First Example of μ-η2:η2-Peroxo-Bridged Macrocyclic Lanthanide Complex. The Crystal Structure of [Lu2{Me2pyo[16]trieneN5}2(μ-η2:η2-O2)Cl2](ClO4)2 Dioxane Solvate

The crystal structure of [Lu2{Me2pyo[16]trieneN5}2(μ-η2:η2-O2)Cl2](ClO4)2(1), where Me2pyo[16]trieneN5 is 2,14-dimethyl-3,6,10,13,19-pentaazabicyclo[13.3.1]nonadeca-1(19),2,13,15,17-pentaene reveals the biologically significant – unprecedented among the lanthanide macrocyclic complexes – planar side-on μ-η2:η2 coordination mode of the peroxide as a result of [1 + 1] template Schiff base cyclocondensation of 2,6-diacetylpyridine with 3,7-diazanonane-1,9-diamine in the presence of mixed lutetium chloride and perchlorate salts followed by slow crystallization process.

Fabrication of Nanostructured Palladium Within Tridentate Schiff-Base-Ligand Coordination Architecture: Enhancement of Electrocatalytic Activity Toward CO2 Electroreduction

There has been growing interest in the electrochemical reduction of carbon dioxide (CO2), a potent greenhouse gas and a contributor to global climate change, and its conversion into useful carbon-based fuels or chemicals [1–5]. Numerous homogeneous and heterogeneous catalytic systems have been proposed to induce the CO2 reduction and, depending on the reaction conditions (applied potential, choice of buffer, its strength and pH, local CO2 concentration, or the catalyst used) various products that include carbon monoxide, oxalate, formate, carboxylic acids, formaldehyde, acetone, or methanol, as well as such hydrocarbons as methane, ethane, and ethylene, are typically observed at different ratios. These reaction products are of potential importance to energy technology, food research, medical applications, and fabrication of plastic materials. Given the fact that the CO2 molecule is very stable, its electroreduction processes are characterized by large overpotentials, and they are not energy efficient. To produce highly efficient and selective electrocatalysts, the transitionmetal-based molecular materials are often considered [6–8]. The latter systems are capable of driving multi-electron transfers and, in principle, produce highly reduced species. In reality, such multi-electron charge transfer catalysts tend to effectively induce the two-electron reduction of CO2 to CO rather than yield highly reduced products in large amounts. Metallic copper electrodes are unique in this respect because they can drive multi-electron transfers. Mechanisms of the successful electrochemical reductions of CO2 to methane and ethylene can be interpreted in terms of complex processes occurring at copper electrodes [9, 10]. It is believed that, during electroreduction, the rate limiting step is the protonation of the adsorbed CO product to form the CHO adsorbate [11]. Significant decrease of the reaction overpotentials can be achieved with the use of the metal complex modified electrodes capable of both mediating electron transfers and stabilizing the reduced products [12]. Because reduction of CO2 can effectively occur by hydrogenation [13], in the present work, we concentrate on such a model catalytic system as nanostructured metallic palladium capable of absorbing reactive hydrogen in addition to the ability to adsorb monoatomic hydrogen at the interface [14–16]. Under such conditions, the two-electron reduction of CO2 typically to CO [12] is favored. When the reaction proceeds on palladium in aqueous KHCO3 solutions, carbon monoxide together with hydrogen and small amounts of formate are produced [17–19]. Further, it has been postulated that CO and COOH adsorbates are expected to be formed at the surfaces of Pd electrodes at −1.0 V (vs. Ag/AgCl) and, subsequently, desorbed at even more negative potentials [20]. To produce highly dispersed and stabilized palladium nanoparticles (as for Fig. 1a), we have generated them by electrodeposition (through consecutive potential cycling) from the thin film of N-coordination complex of palladium(II), [Pd(C14H12N2O3)Cl2]2 MeOH. The ligand and its palladium complex (their detailed crystallographic, IR, and NMR features will be a subject of our next publication) were synthesized via typical condensation reaction as published earlier [21, 22]. The resulting metallic Pd nanoparticles (diameters, 5–10 nm), rather than Pd cationic species, are stabilized and activated by nitrogen coordination centers from the macromolecular matrix. Supramolecular architectures of active and well-defined Schiff-base-ligands containing nitrogen donor atoms are of primary importance because A. Wadas : I. A. Rutkowska : P. J. Kulesza (*) Faculty of Chemistry, University of Warsaw, Pasteura 1, 02093 Warsaw, Poland e-mail: pkulesza@chem.uw.edu.pl

Novel self-assembled supramolecular architectures of Mn(II) ions with a hybrid pyrazine–bipyridine ligand

A new hybrid pyrazine-bipyridine ligand L (C26H20N6) and its complexes with Mn(NO3)2, Mn(ClO4)2, MnCl2 and MnBr2 have been synthesised. By the self-assembly of L and Mn(II) ions three different kinds of supramolecular complexes have been obtained: binuclear baguette complex [Mn2L(H2O)6](NO3)4·2.5H2O 1 and tetranuclear [2 × 2] grid-type complex [Mn4L4](ClO4)8·2.5(CH3CN)·2CH3OH 2 and mononuclear complexes [MnL2]X2 (where X = Cl(-)3 and X = Br(-)4). Crystal structures and magnetic properties of Mn(II) complexes 1 and 2 have been also investigated. The crystal structures reveal that in both 1 and 2 complexes the Mn(II) ions have coordination number 6 and distorted octahedral coordination geometry. In 2 four metal cations and four ligands have assembled into a grid-type [2 × 2] array, with a perchlorate anion occupying the central cavity, with clearly a good fit for the center of the cavity. The perchlorate anion, in contrast to the nitrate anion, probably acts as a template in the formation of tetranuclear grid-type complexes. Magnetic susceptibility measurements indicate that the Mn(II) ions are all high spin, and in both 1 and 2 complexes there are weak antiferromagnetic interactions between Mn(II) ions.