Photocatalytic reactions of a nickel(II) annulene complex incorporated in polymeric structures

The photochemical reactions of the Ni(II) annulene complex, [NiII([5,7,12,14]-tetra methyl dibenzo[2,3- b:2,3-b,i][1,4,8,11]tetraaza[14]annulenate)], grafted into a poly(isobutylene-alt-maleate) backbone were investigated in aqueous media. The grafted Ni(II) complex becomes soluble in aqueous and organic solvents where the strands form aggregates with medium-dependent shapes. Irradiation of the polymer at 532 or 351 nm produce charge-separated macrocyclic pendants, CS, with a lifetime s 30 ns. CS reacts with electron donors and acceptors before it decays with a lifetime s 1 ms. In parallel to the decay of CS, an excited state-excited state annihilation process gives rise to luminescence whose spectrum spans wavelengths shorter than the wavelength of the irradiation, lex > 500 nm. Theoretical calculations were carried out with the aim of understanding the morphology and structures of strand aggregates, to confirm the nature of reaction products and to account for the spectroscopic and photochemical properties of the Ni(II) pendants. The endothermic reduction of CO2 to CO by S(IV) species was used as a test of the Ni(II) complex´s ability to photocatalyze the reaction. In the photoprocess, the Ni(II) complex fulfills the double role of antenna and catalyst.Fil: Estiu, G.. University Of Notre Dame-indiana; Estados UnidosFil: Ferraudi, G.. University Of Notre Dame-indiana; Estados UnidosFil: Lappin, A. G.. University Of Notre Dame-indiana; Estados UnidosFil: Ruiz, Gustavo Teodosio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Vericat, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Costamagna, J.. Universidad de Santiago de Chile; ChileFil: Villagrán, M.. Universidad de Santiago de Chile; Chil

Photophysical properties of [(norharmane)Re(CO)3 (L)]+ complexes (L = bpy, phen or dppz). Redox behavior of the excited states and their interaction with Calf Thymus DNA

The photochemical and photophysical properties of [(nHo)Re(CO)3(L)]+ complexes, where nHo = 9H-pyrido[3,4-b]indole and L = 2,2′ bipyridine (bpy), 1,10 phenantroline (phen) or dipyridil[3,2-a:2′3′-c]phenazine (dppz) were investigated by Laser Flash Photolysis (LFF) and Pulse Radiolysis (PR) techniques. While complexes with L = bpy or phen show absorption transients compatible with MLCTRe→L excited states, [(nHo)Re(CO)3(dppz)]+ showed an excited state assignable to a dppz-centered, 3ππ*dppz. In aqueous solutions, the last complex does not generate any absorption transient. However, when Calf thymus DNA was added, the same absorption spectrum was obtained. These results suggest that this complex can intercalate into DNA. The species generated in either reductive or oxidative conditions in LFF experiments were compared with those obtained in PR. Also, the quenching rate constants (kq) of the excited states with MV2+ were calculated. The intercalation of the [(nHo)Re(CO)3(dppz)]+ into DNA, increases kq ∼100 times. This result is rationalized in terms of the conditions created by the intercalation using the biopolymer as a well-organized matrix.Fil: Maisuls, Iván. 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); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: 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: Lappin, Alexander G.. University of Notre Dame-Indiana; Estados UnidosFil: Ruiz, Gustavo Teodosio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Ferraudi, Guillermo J.. University of Notre Dame-Indiana; Estados Unido

Photochemical properties of a Re(I) polymer containing dppz in its structure : An interplay between dark and bright states of dppz

A new polymer, P4VP-Re(dppz), based on the poly-4-vinylpyridine structure containing Re(CO)3(dppz)⁺ pendants was synthesized. Multiple morphologies of P4VP-Re(dppz), such as vesicles, spherical nanoaggregates, large vesicle compounds, rings and pyramidal structures were observed by AFM and TEM in cast films of P4VP-Re(dppz) in solvents of different polarity and solvent/acid mixtures. Several conformations of a model monomer of P4VP-Re(dppz) were studied by TD-DFT to ascertain the effect of protonation over the molecular structure as well as over the absorption spectroscopy of P4VP-Re(dppz). P4VP-Re(dppz) excited states and their redox reactivity towards the sacrificial reductant TEOA were studied by flash photolysis experiments either in DMF and in DMF/HClO4. Those experiments were compared to the ones derived from thermal reactions of P4VP-Re(dppz) with solvated electrons in pulse radiolysis experiments. All the photophysical and photochemical properties studied were rationalized in terms of an interplay between 3IL(ππ*), 3MLCT(phz) and the 3MLCT(phen) states.Facultad de Ciencias ExactasInstituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ingenierí

Photophysics, photochemistry and thermally-induced redox reactions of a (Pterin)rhenium(I) complex

In this work, we present a whole and deep study on the thermal redox and the photophysical and photochemical reactions of a tricarbonyl Re(I) complex coordinating Pterin, fac-ReI(CO)3(pterin)(H2O) (pterin = 2-amino-4-oxo-3H-pteridine). In aqueous solutions, the fluorescence of the complex is attributed to the emitting 1IL state (τemi ∼ 7.6 ns). In MeCN, however, the luminescence was ascribed to an overlapping dual emission from 1IL and 3MLCT states (τemi1 = 8.0 ns and τemi2 = 1.0 μs). Oxygen quenching of the 3MLCT based luminescence occurred with kq = 1.6 × 109 M−1 s−1. In glasses at 77 K, nevertheless, the 3MLCT prevailed over 1IL states. Flash photolysis experiments in aqueous solutions showed the spectrum of 3IL while in MeCN the presence of 3MLCT was evident. Pulse radiolysis experiments under oxidizing and reducing environments were performed in aqueous solutions of the Re-Pterin complex. By performing multivariate curve resolution − alternating least-squares (MCR-ALS), two species were identified under reducing conditions: an intermediate related to the semireduced radical of pterin ligand and the dihydrogenated [Re(CO)3(7,8-PtrH2)(H2O)] product. TD-DFT calculations helped to ascertain the nature of these species. Flash photolysis experiments where the excited states were reduced with triethylamine were in good agreement with pulse radiolysis experiments under reductive conditions. The oxidized transient spectrum was also obtained by pulse radiolysis, which compares very well with those published for Re(II) species, leading us to propose oxidation in the metal core as the reaction product of the transient under oxidizing conditions. The combination of different spectroscopic techniques along with the theoretical calculation allowed elucidating the nature, dynamics and reactivity of the excited states prevail in a Re-Pterin complex. This is of the particular importance considering that equivalent studies have not been reported for any other rhenium complex of substituted pterins nor for complexes of other transition metal ions of pterin derivatives.Fil: Ragone, Fabricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: David Gara, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Garcia Einschlag, Fernando Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Lappin, Alexander G.. University of Notre Dame; Estados UnidosFil: Ferraudi, Guillermo J.. University of Notre Dame; Estados UnidosFil: Wolcan, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Ruiz, Gustavo Teodosio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Photochemical properties of a Re(I) polymer containing dppz in its structure. An interplay between dark and bright states of dppz

A new polymer, P4VP-Re(dppz), based on the poly-4-vinylpyridine structure containing Re(CO)3(dppz)+ pendants was synthesized. Multiple morphologies of P4VP-Re(dppz), such as vesicles, spherical nanoaggregates, large vesicle compounds, rings and pyramidal structures were observed by AFM and TEM in cast films of P4VP-Re(dppz) in solvents of different polarity and solvent/acid mixtures. Several conformations of a model monomer of P4VP-Re(dppz) were studied by TD-DFT to ascertain the effect of protonation over the molecular structure as well as over the absorption spectroscopy of P4VP-Re(dppz). P4VP-Re(dppz) excited states and their redox reactivity towards the sacrificial reductant TEOA were studied by flash photolysis experiments either in DMF and in DMF/HClO4. Those experiments were compared to the ones derived from thermal reactions of P4VP-Re(dppz) with solvated electrons in pulse radiolysis experiments. All the photophysical and photochemical properties studied were rationalized in terms of an interplay between 3IL(ππ*), 3MLCT(phz) and the 3MLCT(phen) states.Fil: Saavedra Moncada, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Gutiérrez Pineda, Eduart Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Maisuls, Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Ruiz, Gustavo Teodosio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Lappin, Alexander G.. University of Notre Dame; Estados UnidosFil: Ferraudi, Guillermo J.. University of Notre Dame; Estados UnidosFil: Wolcan, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Photophysical properties of [(norharmane)Re(CO)3 (L)]+ complexes (L = bpy, phen or dppz): redox behavior of the excited states and their interaction with Calf Thymus DNA

The photochemical and photophysical properties of [(nHo)Re(CO)3(L)]+ complexes, where nHo = 9H-pyrido[3,4-b]indole and L = 2,2′ bipyridine (bpy), 1,10 phenantroline (phen) or dipyridil[3,2-a:2′3′-c]phenazine (dppz) were investigated by Laser Flash Photolysis (LFF) and Pulse Radiolysis (PR) techniques. While complexes with L = bpy or phen show absorption transients compatible with MLCTRe→L excited states, [(nHo)Re(CO)3(dppz)]+ showed an excited state assignable to a dppz-centered, 3ππ*dppz. In aqueous solutions, the last complex does not generate any absorption transient. However, when Calf thymus DNA was added, the same absorption spectrum was obtained. These results suggest that this complex can intercalate into DNA. The species generated in either reductive or oxidative conditions in LFF experiments were compared with those obtained in PR. Also, the quenching rate constants (kq) of the excited states with MV2+ were calculated. The intercalation of the [(nHo)Re(CO)3(dppz)]+ into DNA, increases kq ∼100 times. This result is rationalized in terms of the conditions created by the intercalation using the biopolymer as a well-organized matrix.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Efecto de las propiedades morfológicas sobre las propiedades fotofísicas del grupo colgante -Re(CO)3(PHEN) unido al esqueleto de la poli-4-vinilpiridina

Las propiedades fotoquímicas y fotofísicas del polímero Re-P4VP, donde los cromóforos de -Re(I)(CO)3(phen) están unidos a la cadena de la poli-4-vinilpiridina, fueron interpretadas en base a las transformaciones morfológicas del mismo. La morfología del Re-P4VP se estudió bajo diferentes medios y condiciones de concentración por las técnicas de TEM y AFM. Los resultados de estos estudios en Re-P4VP y Re-P4VP en presencia de HClO4, Re-P4VPHnn+, revelaron que sus morfologías son dependientes de la concentración del polímero de Re(I). Estos cambios morfológicos tienen una influencia directa en las propiedades fotofísicas del polímero de Re-P4VP, siendo responsables de un incremento significativo del tiempo de vida del estado excitado MLCTRe(I) ? phen con la concentración del polímero y de un aumento de casi 8 veces en el rendimiento cuántico de luminiscencia después de la protonación del Re-P4VP.Facultad de Ciencias Agrarias y Forestale