No abstract

. Can. J . Chem. 63, 602 (1985).The synthesis of the linked porphyrin-cyclodextrin 3 and its zinc complex 4 is described and their characterization by ' H nmr, ''C nmr, circular dichroism, ultraviolet, and infrared spectroscopy is reported. The linked porphyrin-cyclodextrin compounds exhibited perturbed electronic absorption and emission spectra which are consistent with their adopting two conformations, one extended with little interaction between the porphyrin and cyclodextrin, and the other folded with the cyclodextrin weakly complexed to the porphyrin. Quenching of the porphyrin excited state of 3 by benzoquinone was examined by measurement of the fluorescence lifetime as a function of quinone concentration; the results suggest that the porphyrin excited state can be quenched intermolecularly by benzoquinone and also intramolecularly by quinone complexed within the cyclodextrin cavity.MONICA C. GONZALEZ et ALAN C. WEEDON. Can. J. Chem. 63, 602 (1985).On dCcrit la synthkse du composC 3 (cyclodcxtrine-porphyrine liees) et de son complexe de zinc (4) ainsi que leur caractkrisation par les spectroscopies infrarouge, ultraviolette et rmn ' H et ' " ainsi que par leur dichroi'sme circulaire. Les composCs lies de cyclodextrine-porphyrine presentent des spectres d'absorption et d'kmission electronique qui sont perturb& et qui sont en accord avec le fait qu'ils adoptent deux conformations: une ktendue, dans laquelle il n'existe que peu d'interactions entre la cyclodextrine et la porphyrine, et une autre replike, dans laquelle la cyclodextrine est faiblement complexCe par la porphyrine. En mesurant le temps de vie de la fluorescence en fonction de la concentration de quinone, on a examine la reaction de p~tgeage, par la benzoquinone, de I'etat excite de la porphyrine presente dans 3; les resultats suggkrent que I'Ctat excite de la porphyrine peut &tre piCgC d'une facon intermoleculaire par la benzoquinone et aussi d'une facon intramolCculaire par de la quinone qui est complexee dans la cavitC de la cyclodextr~ne.[Traduit par le journal]

Immobilization of PEG-covered silicon dots, PEGSiDs, on glass substrates was performed following a simple strategy involving particle embedding by a sol-gel process forming a silica film on glass slides. The obtained films, denoted as fSiO x -PEGSiD, constitute a water-wettable, strongly supported, photoluminescent glass coating. The films showed high capacity for photosensitizing singlet oxygen (1O2) in the UVA when immersed in water. Staphylococcus aureus colonies formed on fSiO x -PEGSiDs modified glasses revealed the inhibition of bacterial adhesion and bacterial growth leading to the formation of loosely-packed and smaller S. aureus colonies. Upon 350 nm light irradiation of the biofilmed fSiO x -PEGSiDs -modified glasses, S. aureus growth was inhibited and bacteria killed reducing the number of living bacteria by three orders of magnitude. Eradication of attached bacteria was achieved by the synergistic effect exerted by a less adherent fSiO x -PEGSiDs surface that inhibits biofilm formation and the ability of the surface to photosensitize 1O2 to kill bacteria.

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