Photoprocesses of chlorin e6 glucose derivatives

The ground and excited state processes of chlorin e6, the monomethyl ester C1, the glucose derivative C2 and the 3-heptylchlorin-glucose C3, were studied in solvents of lower and higher polarity. The excited singlet and lowest triplet states of C1-C3 were characterized by spectroscopic methods for several conditions. The quantum yields of formation of singlet molecular oxygen and the other triplet properties of the three chlorins and chlorin e6 are similar, whereas the fluorescence quantum yield decreases on going from C1 to C3. Time-resolved optoacoustic experiments revealed a ca. 30 kJ mol(-1) higher triplet level for C3 with respect to C1/2

In vitro photoactivation of newly synthesized chlorin derivatives with red light emitting diodes

We investigated the in vitro photo-activation properties of two chlorinderivatives, i.e. 8-cis-heptylchlorin dicarboxylic acid and 3-trans-heptylchlorin bisamidoglucose derivative, which exhibit lipophilic properties similar to those of the active fractions of Photofrin II, on a normal epithelial cell line (FRTL-5). We used as an irradiation source an array of diodesemittingredlight (λ = 675 nm), which produced a fluence of 7 MW cm−2 on the cells. We found that photo-activation with chlorinderivatives in the concentration range 1–100 ng ml−1 greatly enhanced the mortality of the irradiated cells (energy density, 0.25 J cm−2) with respect to the control cells kept in the dark. This response is immediate and appears to be an ‘all or none’ effect. Taking into account that compounds exhibit a strong absorbance peak in the long wavelength region of visible light where tissues are relatively transparent, our results suggest that chlorins can be considered to be good candidates for application in photodynamic therapy

Electronic excitations of C 60 aggregates

Excitation properties of the isolated C 60 and (C 60) N model clusters (N = 2, 3, 4, 6 and 13) are studied using an a priori parameterized and self-consistent Hamiltonian, the Complete Neglect of Differential Overlap considering the l azimuthal quantum number method. This method properly describes electron excitations of the isolated C 60 after the configuration interaction of singles (CIS) procedure, when those are compared with experimental data in n-hexane solution and in a molecular beam. Geometry models of (C 60) N clusters to model the effect of aggregation were obtained from the fullerene fcc crystal. Some peaks in the low energy edge of the absorption spectrum appear corresponding to clustering effects, as well as small increases of bandwidths in the strong bands at the UV region. An analysis of the theoretical absorption spectrum for dimer models has been carried out, taking into account the influence of the distance between fullerene centers. The density of states of CIS fo

N-cyclopropylimine-1-pyrroline rearrangement. A novel photochemical reaction

matrix presented A novel aza-(vinylcyclopropane-cyclopentene) photochemical rearrangement is reported. 1-Pyrrolines are easily synthesized in good yields from N-cyclopropylimines. Hydrogen, alkyl, and aryl groups can be placed anywhere within the system, and the reaction proceeds regiospecifically

Photochemistry of Imine-Group VI Carbene Complexes with Alkenes: Synthetic Scope and Photochemical Aspects

The irradiation of imine-group VI carbene complexes with alkenes leads to the formation of 1-pyrrolines through a mechanism involving an initial cyclopropanation followed by a light-induced [1,3]-sigmatropic rearrangement. The reaction has no limitations on the structural nature of the imine-carbene complexes and is general for terminal and acyclic or cyclic 1,2-disubstituted electron-poor olefins. From the studies on photochemical aspects such as excited-state quenching, quantum yield, excited-state sensitizers and Stern-Volmer plots, it is concluded that both excited states, singlet and triplet, undergo the photoreaction. As far as we know, this is the first photochemical study on these kinds of compounds