Showing papers by "Luis G. Arnaut published in 1998"
TL;DR: In this paper, photoacoustic calorimetry was used to measure the quantum yields of singlet molecular oxygen production by the triplet states of tetraphenylporphyrin (TPP), ZnTPP and CuTPP in toluene, yielding values of 0.67 0.14, 0.68 0.19 and 0.03 0.07 quantum yield.
Abstract: Photoacoustic calorimetry was used to measure the quantum yields of singlet molecular oxygen production by the triplet states of tetraphenylporphyrin (TPP), ZnTPP and CuTPP in toluene, yielding values of 0.67 0.14, 0.68 0.19 and 0.03 0.01, respectively. We show that a novel dichlorophenyl derivative of ZnTPP is capable of singlet-oxygen production with a 0.90 0.07 quantum yield. The synthesis and characterisation of a new photostable chlorin with high absorptivity in the red that is capable of singlet-oxygen production with 0.54 0.06 quantum yield is described. Our results suggest that chlorinated chlorins may be interesting new sensitisers for photodynamic therapy.
209 citations
TL;DR: The microscopic descriptions of electron transfer reactions given by Marcus theory and by the intersecting-state model (ISM) are compared with ab initio calculations on O2/O2- and C6H6/C6.
Abstract: The microscopic descriptions of electron transfer (ET) reactions given by Marcus theory (MT) and by the intersecting-state model (ISM) are compared with ab initio calculations on O2/O2- and C6H6/C6...
50 citations
TL;DR: In this article, the Intersecting State Model (ISM) is used to estimate activation barriers and reactive bond distances for reactions involving the transfer of hydrogen atoms, and the results are compared with available experimental, semi-empirical or ab initio data.
Abstract: We propose the use of the Intersecting-State Model (ISM) to estimate activation barriers and reactive bond distances for reactions involving the transfer of hydrogen atoms. The method is used in a variety of systems with transition states of the (H)C–H–C(H), N–H–C(H), O–H–C(H), S–H–C(H), Si–H–C, Si–H–Si, Sn–H–C and Ge–H–C types. Hydrogen abstractions by halogen atoms are also investigated. Results are compared with available experimental, semi-empirical or ab initio data. Other transition state types (such as O–H–O) which cannot be properly rationalized in the light of an elementary bond-breaking/bond-forming process are also analyzed.
17 citations
TL;DR: In this paper, the authors calculated the electron transfer rate in protein systems with various donor acceptor distances, reaction-free energies and temperatures, as the product of an electron tunneling probability and a nuclear distortion activation term.
Abstract: Electron transfer rates within protein systems with various donor acceptor distances, reaction-free energies and temperatures, are calculated as the product of an electron tunneling probability and a nuclear distortion activation term. The electronic factor is given by the frequency of electronic motion in the donor, the donor electron energy, the donor–acceptor distance and the protein refractive index. Nuclear distortion is obtained from bond lengths, force constants and bond orders of the co-factor bonds involved in the reaction coordinate. The nuclear factor is calculated according to thermal activation and nuclear tunneling mechanisms. The calculation of distance, free-energy and temperature dependence of photoinduced-intraprotein electron transfer rates in Ru/Zn-modified cytochromes and myoglobins does not rely on fitting unknown parameters to kinetic data and is in good agreement with the experiment. Systems with reduced masses lower than 100 a.m.u. may undergo sizable nuclear tunneling at room temperature.
6 citations