Synthesis and photochemical study of a new norbornadiene-derivative with potential as a molecular system for the storage of solar-thermal energy

Norbornadiene derivatives (NBD) have recently emerged as a promising alternative in the development of molecular systems for the storage of solar-thermal energy (MOST). In these systems, the energy is stored in the form of chemical bonds by photoisomerization reactions, and the stored energy can be released on demand in the form of heat. In this contribution, we present results regarding the photochemical behavior of a new NBD, i.e., 2-cyano-3-((4 (diethylamino)phenyl)ethinyl)norbornadiene (NBD1). This compound contains an electron-withdrawing group (CN), and an electron-donor group (ethinyl-derivative) in one of the double bonds of the bicycle-ring. As a consequence, a conjugated push-pull system was obtained, with led to an absorption band peaked at the visible region. The irradiation of NBD1 in toluene solution promotes the formation of the quadricyclane isomer, for which a maximum at about 310 nm was detected. Photoconversion seems to proceed almost quantitatively after ca. 30 minutes of irradiation.Agencia Nacional de Investigación e Innovació

Phycocyanin as Potential Natural Dye for its Use in Photovoltaic Cells

Phycocyanin, a blue protein extracted from Spirulina spp, shows promising characteristics that made it suitable for its use as natural dye in photovoltaic devices as the dye sensitized solar cells. In this work, a study of the aqueous solution-phase photochemistry, photophysics, spectroscopy, voltammetry and thermal stability of phycocyanin is presented. Suitable redox potentials (Eox = 1.2 V vs. Ag/AgCl) and a value of 1.96 V for E0,0 (i.e., the energy difference between the vibrationally relaxed levels of the first electronic excited state, S1, and the ground state, S0 of phycocyanin), allows the calculation of energetic profiles that in comparison with the conduction band of the anatase-TiO2 and I-/I3- electrolyte, could predict electron transfer with these components of the cell. The data reported herein should not only help to evaluate the potential use of phycocyanin as sensitizer for solar cells, but should also help in the development of novel solar cells where the photoinduced behavior of this protein can be controlled

Phycocyanin as Potential Natural Dye for its Use in Photovoltaic Cells

Phycocyanin, a blue protein extracted from Spirulina spp, shows promising characteristics that made it suitable for its use as natural dye in photovoltaic devices as the dye sensitized solar cells. In this work, a study of the aqueous solution-phase photochemistry, photophysics, spectroscopy, voltammetry and thermal stability of phycocyanin is presented. Suitable redox potentials (Eox = 1.2 V vs. Ag/AgCl) and a value of 1.96 V for E0,0 (i.e., the energy difference between the vibrationally relaxed levels of the first electronic excited state, S1, and the ground state, S0 of phycocyanin), allows the calculation of energetic profiles that in comparison with the conduction band of the anatase-TiO2 and I-/I3- electrolyte, could predict electron transfer with these components of the cell. The data reported herein should not only help to evaluate the potential use of phycocyanin as sensitizer for solar cells, but should also help in the development of novel solar cells where the photoinduced behavior of this protein can be controlled.Fil: Enciso, Paula. Facultad de Ciencias. Laboratorio de Biomateriales. Montevideo; UruguayFil: Cabrerizo, Franco Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Gancheff, Jorge S.. Facultad de Química. Cátedra de Química Inorgánica. Montevideo; UruguayFil: Denis, Pablo A.. Facultad de Química. Montevideo; UruguayFil: Cerdá, Maria Fernanda. Facultad de Ciencias. Laboratorio de Biomateriales. Montevideo; Urugua

Solution Phase Photolysis of 1,2-Dithiane Alone and with Single-Walled Carbon Nanotubes

Photolysis of 1,2-dithiane (<b>1</b>) in acetonitrile with single walled carbon nanotubes (SWCNTs) was earlier reported to form thiol-functionalized SWCNTs via the butane-1,4-dithiyl diradical (<b>2</b>). The present study shows that <b>2</b> instead undergoes a facile rearrangement to thiophane-2-thiol (<b>6</b>). This photoreaction is clean, rapid, and irreversible under 313 nm irradiation. The secondary photolysis of <b>6</b> with SWCNTs at a shorter wavelength (254 nm) leads to 2-thiophanyl radicals <b>8</b>, which derivatize SWCNTs by covalent attachment. Pyrolysis of the resulting “sulfurized SWCNTs” affords a mixture of organosulfur compounds, including thiophene formed by dehydrogenation. An unknown additional mechanism causes high TGA weight loss and a large incorporation of sulfur

Complex salts of [Re^II(NO)Br₄(pyz)]⁻: synthesis, crystal structures, and DFT studies

<div><p>Two nitrosyl Re(II) complexes formulated as [Ni(bipy)₃][Re(NO)Br₄(pyz)]₂ and [Cu(bipy)₂Br][ReNOBr₄(pyz)] (pyz = pyrazine, bipy = 2,2′-bipyridine) were synthesized and characterized by single-crystal X-ray diffraction. The pyrazine in [Re(NO)Br₄(pyz)]⁻ was not able to act as bridge toward a second metal ion, and the two salts were obtained. Computational studies at the density functional level of theory show that the charge on the nitrogen, which could be available for bridging, is dramatically reduced to less than half, decreasing its capability to bind a second metal ion.</p></div

Multi-target heteroleptic palladium bisphosphonate complexes

Bisphosphonates are the most commonly prescribed drugs for the treatment of osteoporosis and other bone illnesses. Some of them have also shown antiparasitic activity. In search of improving the pharmacological profile of commercial bisphosphonates, our group had previously developed first row transition metal complexes with N-containing bisphosphonates (NBPs). In this work, we extended our studies to heteroleptic palladium–NBP complexes including DNA intercalating polypyridyl co-ligands (NN) with the aim of obtaining potential multi-target species. Complexes of the formula [Pd(NBP)₂(NN)]·2NaCl·xH₂O with NBP = alendronate (ale) or pamidronate (pam) and NN = 1,10 phenanthroline (phen) or 2,2′-bipyridine (bpy) were synthesized and fully characterized. All the obtained compounds were much more active in vitro against T. cruzi (amastigote form) than the corresponding NBP ligands. In addition, complexes were nontoxic to mammalian cells up to 50–100 µM. Compounds with phen as ligand were 15 times more active than their bpy analogous. Related to the potential mechanism of action, all complexes were potent inhibitors of two parasitic enzymes of the isoprenoid biosynthetic pathway. No correlation between the anti-T. cruzi activity and the enzymatic inhibition results was observed. On the contrary, the high antiparasitic activity of phen-containing complexes could be related to their ability to interact with DNA in an intercalative-like mode. These rationally designed compounds are good candidates for further studies and good leaders for future drug developments. Four new palladium heteroleptic complexes with N-containing commercial bisphosphonates and DNA intercalating polypyridyl co-ligands were synthesized and fully characterized. All complexes displayed high anti-T. cruzi activity which could be related to the inhibition of the parasitic farnesyl diphosphate synthase enzyme but mainly to their ability to interact DNA.Centro de Química Inorgánic

Multi-target heteroleptic palladium bisphosphonate complexes

Abstract: Bisphosphonates are the most commonly prescribed drugs for the treatment of osteoporosis and other bone illnesses. Some of them have also shown antiparasitic activity. In search of improving the pharmacological profile of commercial bisphosphonates, our group had previously developed first row transition metal complexes with N-containing bisphosphonates (NBPs). In this work, we extended our studies to heteroleptic palladium–NBP complexes including DNA intercalating polypyridyl co-ligands (NN) with the aim of obtaining potential multi-target species. Complexes of the formula [Pd(NBP)2(NN)]·2NaCl·xH2O with NBP = alendronate (ale) or pamidronate (pam) and NN = 1,10 phenanthroline (phen) or 2,2′-bipyridine (bpy) were synthesized and fully characterized. All the obtained compounds were much more active in vitro against T. cruzi (amastigote form) than the corresponding NBP ligands. In addition, complexes were nontoxic to mammalian cells up to 50–100 µM. Compounds with phen as ligand were 15 times more active than their bpy analogous. Related to the potential mechanism of action, all complexes were potent inhibitors of two parasitic enzymes of the isoprenoid biosynthetic pathway. No correlation between the anti-T. cruzi activity and the enzymatic inhibition results was observed. On the contrary, the high antiparasitic activity of phen-containing complexes could be related to their ability to interact with DNA in an intercalative-like mode. These rationally designed compounds are good candidates for further studies and good leaders for future drug developments. Graphic abstract: Four new palladium heteroleptic complexes with N-containing commercial bisphosphonates and DNA intercalating polypyridyl co-ligands were synthesized and fully characterized. All complexes displayed high anti-T. cruzi activity which could be related to the inhibition of the parasitic farnesyl diphosphate synthase enzyme but mainly to their ability to interact DNA. [Figure not available: see fulltext.].Fil: Cipriani, Angelo. Universidad de la República. Facultad de Química; UruguayFil: Rostán, Santiago. Universidad de la República. Facultad de Química; UruguayFil: Leon, Ignacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Li, Zhu Hong. University Of Georgia. Department Of Cellular Biology; Estados UnidosFil: Gancheff, Jorge S.. Universidad de la República. Facultad de Química; UruguayFil: Kemmerling, Ulrike. Universidad de Chile. Facultad de Medicina.; ChileFil: Olea Azar, Claudio. Universidad de Chile; ChileFil: Etcheverry, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Docampo, Roberto. University Of Georgia. Department Of Cellular Biology; Estados UnidosFil: Gambino, Dinorah. Universidad de la República. Facultad de Química; UruguayFil: Otero, Lucía. Universidad de la República. Facultad de Química; Urugua