Estudios fotoquímicos y fotofísicos en complejos tricarbonílicos de Renio(I) y su interacción con biopolímeros

En el trabajo de tesis se presenta la síntesis y caracterización de un nuevo complejo tricarbonílico de Renio(I) coordinado con un ligando pterina [Re(CO)3(pterina)(H2O)]. Se estudian las propiedades fotofísicas de este complejo y de otros tres complejos tricarbonílicos de Renio relacionados. Ademas se estudian los procesos de asociación y fotosensibilización de un grupo de complejos de esta familia a diferentes moléculas de ADN. Finalmente se estudia la asociación del complejo Re(CO)3(pterina)(H2O) con proteínas de transporte.Facultad de Ciencias Exacta

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

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

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

Solvent effects on the photophysical properties of Bu₄N[(4,40-bpy) Re(CO)₃(bpy-5,50-diCOO)] complex : A combined experimental and computational study

The photophysical properties of the complex Bu₄N[(4,4′-bpy)Re(CO)₃(bpy-5,5′-diCOO)] were studied in protic and aprotic media with the aid of steady-state and time-resolved techniques and TD-DFT calculations. The absorption spectrum as well as the steady state and time resolved luminescence of the Re(I) complex display a marked solvent effect. The highest and lowest energy absorption bands experience a bathochromic shift as the polarity of the solvent decreases. In addition, the lowest energy band broadens. Two luminescence bands were observed around 430 and 600 nm in protic organic solvents like alcohols. The high energy emission is observed solely in aqueous solutions, while in aprotic solvents only the low energy luminescence is detected. TD-DFT calculations allowed us to identify the main electronic transitions in the low energy region as ¹MLLCT Re(CO)₃ → 4,4′-bpy and ¹MLLCT Re(CO)₃ → bpy-5,5′-diCOO. The simulated absorption spectra of the Re(I) complex in H2O, protic (EtOH, MeOH) and aprotic (CHCl₃, CH₂Cl₂, CH₃CN) organic solvents follow the experimental absorption spectra with reasonable accuracy both in position and relative intensities. The magnitude of the calculated dipole moment (μ) increases with the dielectric constant of the solvent (εr). Besides, the energy of ¹MLLCT Re(CO)₃ → 4,4′-bpy also increases with εr. However, the energy of the ¹MLLCT Re(CO)₃ → bpy-5,5′-diCOO transition is rather insensitive to εr. This disparity is attributed to the fact that the ¹MLLCT Re(CO)₃ → 4,4′-bpy transition is nearly parallel to the orientation of μ while the ¹MLLCT Re(CO)₃ → bpy-5,5′-diCOO transition is almost perpendicular to it. Unrestricted TD-DFT calculations were successfully applied to the triplet species. It is observed that in the triplet state the Re–N distances are shortened while Re–C distances are elongated relative to the ground state. The calculated emission energy by TD-DFT and/or Δ(SCF) methods was compared to the experimental emission maximum in chloroform. All the experimental results as well as the theoretical calculations indicate that solvent effects on the steady state and time resolved luminescence of the Re(I) complex can be accounted by the coexistence of ³MLLCT Re(CO)₃ → 4,4′-bpy, ³MLLCT Re(CO)₃ → bpy-5,5′-diCOO and ¹IL excited states.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasCentro de Química InorgánicaCentro de Investigaciones Óptica

Photosensitized Generation of Singlet Oxygen from Re(I) Complexes: A Photophysical Study Using LIOAS and Luminescence Techniques

Quantum yields and efficiencies of 1O2 (1Δg) production along with photophysical properties for a number of Re(I) complexes in acetonitrile solutions are reported. Two different classes of Re(I) complexes, LS-CO2-Re(CO)3(bpy) (LS = 2-pyrazine, 2-naphthalene, 9-anthracene, 1-pyrene, 2-anthraquinone) and XRe(CO)3L (X =CF3SO3, py; L = bpy, phen), were probed as photosensitizers for 1O2 (1Δg) production in air-saturated acetonitrile solutions. Depending on the nature of the Re(I) complex, the excited state responsible for the generation of 1O2 (1Δg) is either a metal-to-ligand charge transfer (3MLCT) or a ligand centered (3LC) state. With LS-CO2-Re(CO)3(bpy)complexes, 1O2 (1Δg) is produced by oxygen quenching of 3LC states of anthracene and pyrene with high quantum yields (ΦΔ between 0.8 and 1.0), while the complexes bearing the ligands LS = 2-anthraquinone, 2-pyrazine, and 2-naphthalene did not yield 1O2. XRe(CO)3L complexes generate 1O2 (1Δg) mainly by oxygen quenching of their 3MLCT luminescence with an efficiency of 1O2 (1Δg) formation close to unity. Bimolecular rate constants for the quenching of the XRe(CO)3L complexes? emission by molecular oxygen range between 1 × 109 and 2 × 109 M−1 s−1, and they are all ≤ 1/9kd,in good agreement with the predominance of the singlet channel in the mechanism of 1O2 (1Δg) generation using these Re(I)complexes as photosensitizers. All the experimental singlet oxygen efficiencies are consistent with calorimetric and luminescence data for the studied complexes. With LS-CO2-Re(CO)3(bpy) complexes, calorimetric experiments were utilized in the calculation of the quantum yields of triplet formation; namely ϕT = 0.76 and 0.83 for the triplet states of anthracene and pyrene, respectively.Fil: Ragone, Fabricio. 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: Martínez Saavedra, Héctor Hernando. 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: David Gara, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: 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: Wolcan, Ezequiel. 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; Argentin

Solvent dependent switching of 3MLLCT and 1IL luminescent states in [ClRe(CO)3(Bathocuproinedisulfonate)]2-: Spectroscopic and computational study

Steady state and time-resolved luminescence experiments and calorimetric studies, as well as time-dependent density functional theory calculations performed on [ClRe(CO)3(Bathocuproinedisulfonate)]2−, show that the photophysical properties of the Re(I) anionic complex are determined by the balance between intraligand (1IL) and metal−ligand-to-ligand charge transfer (3MLLCT) excited states. In organic solvents, 3MLLCT states prevail and the usual expected behavior is observed: bathochromic shift of the emission maximum, a reduced luminescence quantum yield and the shortening of the excited-state lifetime upon increasing the polarity of the solvent. In addition, singlet oxygen (1O2) is generated with high quantum yields (ΦΔ ≈ 0.5 in CH3CN) due to the quenching of the 3MLLCT luminescence by 3O2. The total quenching rate constant of triplet state by oxygen, kq,reach values between 2.2 and 2.4 × 109 M−1 s−1 for the organic solvents studied. In CH3CN, the fraction of triplet states quenched by O2 which yield 1O2, f O2T , is nearly unity. In aqueous solution, where no singlet oxygen is generated, the luminescence of the Re(I) complex is of 1IL character with a emission quantum yield (Φem) strongly pH dependent: Φem,(pH=2)/Φem,(pH=10) ≈ 5.6. The variation of the pH of the solution tunes the photophysical properties of the Re(I) complex by changing the relative amount of the different species existing in aqueous solutions:[ClRe(CO)3(BCS)]2−, [(OH)Re(CO)3(BCS)]2− and [(H2O)Re(CO)3(BCS)]−. TD-DFT calculations show that the percentage of charge transfer character of the electronic transitions is substantially higher in the organic solvents than in aqueous solutions, in agreement with the increase of 1IL character of HOMO in [(H2O)Re(CO)3(BCS)]− relative to [ClRe(CO)3(BCS)]2−.Fil: Martínez Saavedra, Héctor Hernando. 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: Ragone, Fabricio. 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: 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: David Gara, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigaciones Opticas (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Wolcan, Ezequiel. 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; Argentin

Association studies to transporting proteins of fac-ReI(CO)3(pterin)(H2O) complex

A new synthetic route to acquire the water soluble complex fac-ReI(CO)3(pterin)(H2O) was carried out in aqueous solution. The complex has been obtained with success via the fac-[ReI(CO)3(H2O)3]Cl precursor complex. ReI(CO)3(pterin)(H2O) has been found to bind strongly with bovine and human serum albumins (BSA and HSA) with intrinsic-binding constants, Kb, of 6.5 × 105 M−1 and 5.6 × 105 M−1 at 310 K, respectively. The interactions of serum albumins with ReI(CO)3(pterin)(H2O) were evaluated employing UV–vis fluorescence and absorption spectroscopy and circular dichroism. The results suggest that the serum albumins-ReI(CO)3(pterin)(H2O) interactions occurred in the domain IIA-binding pocket without loss of helical stability of the proteins. The comparison of the fluorescence quenching of BSA and HSA due to the binding to the Re(I) complex suggested that local interaction around the Trp 214 residue had taken place. The analysis of the thermodynamic parameters ΔG0, ΔH0, and ΔS0 indicated that the hydrophobic interactions played a major role in both HSA-Re(I) and BSA-Re(I) association processes. All these experimental results suggest that these proteins can be considered as good carriers for transportation of ReI(CO)3(pterin)(H2O) complex. This is of significant importance in relation to the use of this Re(I) complex in several biomedical fields, such as photodynamic therapy and radiopharmacy.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: Martínez Saavedra, Héctor Hernando. 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: Garcia, Pablo Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; 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: Arguello, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; 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