1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

4 Summary
Summary 4
Within this thesis, several semi-natural and synthetic cycloketo-porphyrin systems were
synthesized and their properties and usability for different fields of application was
subjected to detailed investigations. Thereby, it was dealt with porphyrin system with an
exocyclic connection of a meso-position or a meso-substituent to a β-pyrrolic carbon atom of
the macrocycle formally originating from an acylation reaction and therewith having a
ketone functionality. Such systems can be found in nature amongst the chlorophylls so that
derivatives of chlorophyll a 1 were in focus of the first part of this thesis. Synthetic analogs,
deriving from “porphyrin building blocks” 28 & 45 - 49 recently introduced by N. JUX, have
been made accessible, characterized and thoroughly investigated within the second part of
this thesis.
Concerning the semi-natural systems, an optimized and highly efficient method for the
isolation of pheophorbides a from spirulina algae has been worked out to easily deliver
amounts up to 1 g of that materials in a quite short time (3 days). With those materials at
hand, it was possible to reproduce and verify the recent findings of M. HELMREICH in
connection with the applicability of such compounds in photosensitizing systems for
photodynamic therapy (PDT). Furthermore, the materials have been used for detailed
investigations on their photophysical and electrochemical properties to be able to compare
them with other sensitizing systems.
To access fully artificial analogs, a synthetic strategy has been developed, starting from
mono-functionalized o-(bromomethyl) substituted „porphyrin building block“ 45 providing a
novel cycloketo-porphyrin system (53) via cyanomethyl derivative 50 and the corresponding
porphyrin ethanoic acid 51. This system exhibits a seven-membered exocycle as major
structural feature. The newly established methodology has also been applied to different
mono- as well as poly-functional building blocks leading to a substance library of free base
cycloketo-porphyrin systems and their corresponding metal complexes which have been
thoroughly investigated by chemical as well as photophysical means.
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