Estudio fotofísico y fotoquímico de complejos de Re(i) mediante las técnicas de laser flash fotólisis y radiólisis de pulso

Re(I)tricarbonyl complexes of the type fac-XRe(CO)3L (where X= halide and/or substituted azine and L=a-diimine and fac indicates that the three carbonyls are on the same face of the octahedron) show exceptionally rich excited-state behavior and redox chemistry as well as thermal and photochemical stability. They have also been used as biological labeling reagents and noncovalent probes for biomolecules and ions. Moreover, there are potential biochemical and technical applications based on the formation of adducts between transition metal complexes of Re(I), and biological macromolecules such as DNA. In this work we present the synthesis and characterization of a new compound Re(CO)3(pterin)(H2O) (pterin 2-amine-4-oxo-3H-pteridine) (RePtas well as studies about the character, dynamics and reactivity of ground and excited states generated by irradiating solutions.De los complejos metálicos de la tercera serie de transición, los tricarbonílicos de Re(I) con ligandos orgánicos, mono ó bidentados, con fórmula general fac-XRe(CO)3L (en donde X= haluro, H2O y/ó azina sustituida, L = ligando bidentado, y fac indica que los tres carbonilos se encuentran en la misma cara del octaedro), muestran un comportamiento extraordinariamente rico tanto en sus estados excitados como en sus reacciones redox, así como también una buena estabilidad térmica y fotoquímica[1]. Además, la posibilidad de coordinar ligandos de interés biológico, permite ampliar el campo de estudio hacia sistemas biológicos y su potencial aplicación biomédica. En este trabajo se presenta la síntesis y caracterización de un nuevo compuesto Re(CO)3(pterina)(H2O) (pterina: 2-amino-4-oxo-3H-pteridina) (RePt) [2], así como estudios sobre la naturaleza, dinámica y reactividad del estado basal y de los estados excitados generados luego de irradiar soluciones.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Estudio fotofísico y fotoquímico de complejos de Re(i) mediante las técnicas de laser flash fotólisis y radiólisis de pulso

Re(I)tricarbonyl complexes of the type fac-XRe(CO)3L (where X= halide and/or substituted azine and L=a-diimine and fac indicates that the three carbonyls are on the same face of the octahedron) show exceptionally rich excited-state behavior and redox chemistry as well as thermal and photochemical stability. They have also been used as biological labeling reagents and noncovalent probes for biomolecules and ions. Moreover, there are potential biochemical and technical applications based on the formation of adducts between transition metal complexes of Re(I), and biological macromolecules such as DNA. In this work we present the synthesis and characterization of a new compound Re(CO)3(pterin)(H2O) (pterin 2-amine-4-oxo-3H-pteridine) (RePtas well as studies about the character, dynamics and reactivity of ground and excited states generated by irradiating solutions.De los complejos metálicos de la tercera serie de transición, los tricarbonílicos de Re(I) con ligandos orgánicos, mono ó bidentados, con fórmula general fac-XRe(CO)3L (en donde X= haluro, H2O y/ó azina sustituida, L = ligando bidentado, y fac indica que los tres carbonilos se encuentran en la misma cara del octaedro), muestran un comportamiento extraordinariamente rico tanto en sus estados excitados como en sus reacciones redox, así como también una buena estabilidad térmica y fotoquímica[1]. Además, la posibilidad de coordinar ligandos de interés biológico, permite ampliar el campo de estudio hacia sistemas biológicos y su potencial aplicación biomédica. En este trabajo se presenta la síntesis y caracterización de un nuevo compuesto Re(CO)3(pterina)(H2O) (pterina: 2-amino-4-oxo-3H-pteridina) (RePt) [2], así como estudios sobre la naturaleza, dinámica y reactividad del estado basal y de los estados excitados generados luego de irradiar soluciones.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

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

Estudio fotofísico y fotoquímico de complejos de Re(i) mediante las técnicas de laser flash fotólisis y radiólisis de pulso

Re(I)tricarbonyl complexes of the type fac-XRe(CO)3L (where X= halide and/or substituted azine and L=a-diimine and fac indicates that the three carbonyls are on the same face of the octahedron) show exceptionally rich excited-state behavior and redox chemistry as well as thermal and photochemical stability. They have also been used as biological labeling reagents and noncovalent probes for biomolecules and ions. Moreover, there are potential biochemical and technical applications based on the formation of adducts between transition metal complexes of Re(I), and biological macromolecules such as DNA. In this work we present the synthesis and characterization of a new compound Re(CO)3(pterin)(H2O) (pterin 2-amine-4-oxo-3H-pteridine) (RePtas well as studies about the character, dynamics and reactivity of ground and excited states generated by irradiating solutions.De los complejos metálicos de la tercera serie de transición, los tricarbonílicos de Re(I) con ligandos orgánicos, mono ó bidentados, con fórmula general fac-XRe(CO)3L (en donde X= haluro, H2O y/ó azina sustituida, L = ligando bidentado, y fac indica que los tres carbonilos se encuentran en la misma cara del octaedro), muestran un comportamiento extraordinariamente rico tanto en sus estados excitados como en sus reacciones redox, así como también una buena estabilidad térmica y fotoquímica[1]. Además, la posibilidad de coordinar ligandos de interés biológico, permite ampliar el campo de estudio hacia sistemas biológicos y su potencial aplicación biomédica. En este trabajo se presenta la síntesis y caracterización de un nuevo compuesto Re(CO)3(pterina)(H2O) (pterina: 2-amino-4-oxo-3H-pteridina) (RePt) [2], así como estudios sobre la naturaleza, dinámica y reactividad del estado basal y de los estados excitados generados luego de irradiar soluciones.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

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

Anion-Dependent Construction of Two Hexanuclear 3D-4F Complexes with a Flexible Schiff Base Ligand

Two hexanuclear 3d-4f Ni-Eu and Cu-Eu complexes [Eu4Ni2L2(OAc)(12)(EtOH)(2)] (1) and [Eu4Cu2L2(OAc)(12)]center dot 2H(2)O (2) are reported which are formed from the salen type Schiff-base ligand H2L (H2L = N,N'-bis(3-methoxysalicylidene)butane-1,4-diamine). In both complexes, four Eu3+ cations are bridged by eight OAc- groups and the chain is terminated at each end by two ML (M = Ni and Cu) units. The structures of 1 and 2 were determined by single crystal X-ray crystallographic studies and the luminescence properties of the free ligand and metal complexes in solution were measured.HHMI Undergraduate Science Education Award 52005907National Science Foundation CHE-0629136, CHE-0741973, CHE-0847763Welch Foundation F-1631, F-816Hong Kong Baptist University FRG/06-07/II-16Hong Kong Research Grants Council HKBU 202407Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)Open Foundation of Jiangsu Province Key Laboratory of Fine Petrochemical Technology KF1005UT-CNM and UT-AustinChemistr

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

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Photochemical and Photophysical Reactions of f ac -Rhenium(I) Tricarbonyl Complexes. Effects from Binucleating Spectator Ligands on Excited and Ground State Processes

Ground and excited state properties of the newly prepared complexes Re(CO)3(2,2¢-biquinoline) LS3(2,2¢-biquinoline) LSS +, LS ) pyrazine or 4,4¢-bipyridine, and Re(CO)3(2,2¢-bipy)(2-pyrazinecarboxylate) were investigated by steady state and time-resolved spectroscopy. The X-ray structure of the latter compound showed that the spectator ligand 2-pyrazinecarboxylate is coordinated through the carboxylate group to Re(I). A component of the complexes’ luminescence was associated with long-lived Re to ligand, 2,2¢-biquinoline or 2,2¢-bipy, charge transfer, while a fast component of the emission was associated with intraligand excited states. Quenching of the luminescence by CuCl2 involved energy transfer via dynamic and static mechanisms. The complexes in their excited states were reduced by 2,2¢,2¢¢-nitrilotriethanol with the formation of Re(I) ligand-radical species. Similar products were generated by the pulse radiolytic reduction of the complexes. The photochemical properties of the 2,2¢-biquinoline complexes and Re(CO)3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed., LS ) pyrazine or 4,4¢-bipyridine, and Re(CO)3(2,2¢-bipy)(2-pyrazinecarboxylate) were investigated by steady state and time-resolved spectroscopy. The X-ray structure of the latter compound showed that the spectator ligand 2-pyrazinecarboxylate is coordinated through the carboxylate group to Re(I). A component of the complexes’ luminescence was associated with long-lived Re to ligand, 2,2¢-biquinoline or 2,2¢-bipy, charge transfer, while a fast component of the emission was associated with intraligand excited states. Quenching of the luminescence by CuCl2 involved energy transfer via dynamic and static mechanisms. The complexes in their excited states were reduced by 2,2¢,2¢¢-nitrilotriethanol with the formation of Re(I) ligand-radical species. Similar products were generated by the pulse radiolytic reduction of the complexes. The photochemical properties of the 2,2¢-biquinoline complexes and Re(CO)3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed.¢-biquinoline or 2,2¢-bipy, charge transfer, while a fast component of the emission was associated with intraligand excited states. Quenching of the luminescence by CuCl2 involved energy transfer via dynamic and static mechanisms. The complexes in their excited states were reduced by 2,2¢,2¢¢-nitrilotriethanol with the formation of Re(I) ligand-radical species. Similar products were generated by the pulse radiolytic reduction of the complexes. The photochemical properties of the 2,2¢-biquinoline complexes and Re(CO)3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed.2 involved energy transfer via dynamic and static mechanisms. The complexes in their excited states were reduced by 2,2¢,2¢¢-nitrilotriethanol with the formation of Re(I) ligand-radical species. Similar products were generated by the pulse radiolytic reduction of the complexes. The photochemical properties of the 2,2¢-biquinoline complexes and Re(CO)3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed.¢,2¢¢-nitrilotriethanol with the formation of Re(I) ligand-radical species. Similar products were generated by the pulse radiolytic reduction of the complexes. The photochemical properties of the 2,2¢-biquinoline complexes and Re(CO)3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed.¢-biquinoline complexes and Re(CO)3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed.3(1,10-phen)4-nitrobenzoate are compared, and the mechanisms of their photochemical reactions are discussed.Fil: Guerrero, J.. Universidad de Santiago de Chile; ChileFil: Piro, Oscar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata; ArgentinaFil: 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: Feliz, Mario Ruben. 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, G.. University of Notre Dame; Estados UnidosFil: Moya, S. A.. Universidad de Santiago de Chile; Chil