Synthesis, spectroscopic and photophysical properties of phthalocyanines bearing dendritic fragments

This thesis reports the synthetic, spectroscopic, and photophysical studies of several series of phthalocyanines bearing polyaryl ether dendritic fragments. Special emphasis has been placed on those which are soluble in water and non-aggregated in solutions.; Chapter 1 reviews the general synthesis of differently substituted phthalocyanines. Examples of water-soluble phthalocyanines with bulky substituents are mentioned. In addition, dendritic phthalocyanines together with the porphyrin analogues are also briefly reviewed.; Chapter 2 describes the synthesis of a series of dendritic zinc(II) phthalocyanines with terminal ester or carboxylate moieties. The higher generations of these compounds exist mainly in monomeric form in solutions, giving an intense fluorescence emission even in very polar aqueous media. They undergo a rapid photoinduced electron transfer with various quenchers and intramolecular energy transfer in which the excited dendrons funnel the energy to the central phthalocyanine which acts as an energy trap. The latter remarkable property suggests that a new and efficient light-harvesting system can be developed based on dendritic phthalocyanine systems.; An extension of this study to a related series of metal-free phthalocyanines with terminal carboxylic acid moieties is described in Chapter 3. Their aggregation behavior has been studied by UV-vis spectroscopy. These compounds can form water-soluble phthalocyanines after being deprotonated with n-butylamine forming the corresponding ammonium carboxylates. The interactions of these novel compounds with a range of surfactants in water have also been investigated with absorption and fluorescence spectroscopy. The results show that these dendritic phthalocyanines can serve as sensors for cationic surfactants.; Chapter 4 discusses another series of dendritic phthalocyanines in which the dendritic fragments contain additional benzene rings in a more congested manner. Apart from the zinc phthalocyanines with four dendritic substituents, silicon phthalocyanines with two axial dendritic fragments are also described. Compared with the former series of macrocycles, these latter compounds undergo a slower photoinduced electron transfer with various quenchers. The energy transfer efficiencies from the excited dendrons to the central phthalocyanine cores have also been studied. The energy transfer quantum yields range from 10 to 16%. At the end of this thesis, selected 1H and 13C NMR spectra are given as an Appendix .