Abstract
The present report is concerned with the designing, obtaining and characterization of novel light –sensitive molecules, belonging to second generation meso-tetraarylporphyrin derivatives. A new structure of A3B porphyrin, namely: 5-(4-pyridyl)-10,15,20-tris(4- phenoxyphenyl)-porphyrin was synthesized in fair yield by multicomponent reaction and characterized by 1H-NMR, FT-IR, UV-vis, fluorescence, MS, HPLC, TLC, AFM and XRD techniques. Tailoring porphyrins by introducing a pyridyl substituent in one of the meso-aryl groups confers some degree of hydrophilicity and may cause absorption and fluorescence emission bands in the long wavelength region. Besides, as it was expected, because of the relatively rigid planar structure, due to substitution with three phenoxy substituents, this porphyrin is characterized by a value of 0.219 for fluorescence quantum yield, a higher value in comparison with usual porphyrins. In solution, by UV-vis and fluorescence spectra, the effects of pH and concentration upon H and J aggregates of the porphyrin are discussed. Xray diffraction and atomic force microscopy investigations proved that this newly synthesized porphyrin is able to generate stable selfassembly in preferred orientations, such as multilayer of lamellar triangles, densely packed and homogeneous, with dimensions around 440 nm, finally forming pyramidal type structures. CHCl3 favors the spiral organization of the pyramids so that rings and even tubes of various diameters ranging from 1μm to 4.5 μm were formed.
Keywords: AFM, A3B porphyrin, Fluorescence spectra, Light-sensitive molecules, Self-assembling, UV-vis spectroscopy, X-ray diffraction.
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Catalytic C-H bond activation as a tool for functionalization of heterocycles
The major topic is the functionalization of heterocycles through catalyzed C-H bond activation. The strategies based on C-H activation not only provide straightforward formation of C-C or C-X bonds but, more importantly, allow for the avoidance of pre-functionalization of one or two of the cross-coupling partners. The beneficial impact of ...read more
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