Franz-Peter Montforts

Simple Synthesis of a Chlorin – Fullerene Dyad with a Novel Ring-Closure Reaction

To model the photosynthetic reaction center, the chlorin - fullerene dyad 1 was synthesized in a one-pot reaction from a linear tetrapyrrole and C(60). It is the first dyad of this type which contains a fullerene and a chlorin unit, the chromophore of naturally occurring photosynthetic systems.

Self-assembled monolayer of an iron(III) porphyrin disulphide derivative on gold

A novel iron(III) porphyrin disulphide derivative have been successfully immobilised on gold surfaces by self-assembly. The redox response of the modified electrodes was compared with the obtained for a similar iron porphyrin in solution, confirming the immobilisation of the metalloporphyrin. The gravimetric data obtained by electrochemical quartz crystal microbalance (EQCM) during adsorption allowed an estimation of the electrode coverage, providing further evidence for the formation of the porphyrin SAM. The modified electrodes were also measured by conventional and imaging ellipsometry. The electrocatalytic activity of the two modified electrodes was tested for the reduction of the molecular oxygen.

Poly(pyrrole-metallodeuteroporphyrin)electrodes: towards electrochemical biomimetic devices

New Cu (II), Mn (III) and Fe (III) deuteroporphyrins functionalized by two electropolymerizable pyrrole groups have been synthesized. The electrooxidation of these metallodeuteroporphyrins has allowed the formation of conducting polypyrrole films exhibiting electrochemical behavior identical to that of the corresponding monomers. In addition, the efficient immobilization of metallodeuteroporphyrins was corroborated by spectrophotometric measurements. Moreover, the potential electrocatalytic properties of Mn (III)-based polypyrrole films in the presence of dioxygen and benzoic anhydride have been illustrated by cyclic voltammetry. Furthermore, the recognition properties of Fe (III)-based polypyrrole films have been highlighted with cyanide in organic electrolyte. Preliminary experiments have also demonstrated the feasibility of such recognition processes in aqueous media.

Synthesis of Metalloporphyrins and Metallochlorins for Immobilization on Electrode Surfaces

New metalloporphyrinoid complexes functionalized with two pyrrole groups and bearing two phosphonate residues have been synthesized starting from readily accessible deuterioporphyrin derivatives. The functional pyrrole groups allow the formation of metalloporphyrinoid films on electrodes by oxidative electropolymerization. On the other hand, the phosphonate functionalities could be used to immobilize the metalloporphyrinoids on polycrystalline titanium dioxide electrodes. Electrodes modified by immobilization of the metalloporphyrinoid complexes have been shown to be useful for electrocatalysis and as electrochemical sensors.

A useful preparation of pyrroles from α,β-unsaturated sulfones

Abstract The addition of alkyl isocyanoacetate to α,β-unsaturated sulfones, which are easily obtained from olefins, affords a convenient access to pyrroles with unusual substitution patterns.

A convenient synthesis of the nitrite reducing cofactor heme d1 from hematoporphyrin

Abstract The nitrite reducing cofactor heme d 1 1 or ent- 1 has been synthesized in few synthetic steps, starting from readily accessible hematoporphyrinester rac- 2 . A single crystal structure analysis of the synthesized target molecule unequivocally establishes the so far unknown relative configuration of heme d 1 .

A Taylor made lipophilic chlorin for Photodynamic Tumor Therapy

Abstract A new chlorin dicarboxylic acid 3 has been synthesized from the porphyrin 1 by amide acetal Claisen rearrangement. The chemical purity, photophysical properties, and its lipophilicity make the chlorin 3 promising camdidate for application in Photodynamic Tumor Therapy (PDT).

Chapter 1 The synthesis of chlorins, bacteriochlorins, isobacteriochlorins and higher reduced porphyrins

Summary Until to date all types of hydroporphyrins ranging from the chlorin (dihydroporphyrin) tothe dodecahydro porphyrin have been prepared. The upper limit in the spectrum of hydroporphinoid structures occurring as natural products is currently represented by the dodecahydroporphyrin factor F 430 34 . It remains to be seen whether nature has been able to produce more highly reduced porhyrins or the missing octahydro- and decahydro links in the spectrum of naturally occurring hydroporphyrins.

Efficient post-processing of aqueous generator eluates facilitates 68Ga-labelling under anhydrous conditions

Abstract The present study reports a convenient method for 68Ga-labelling under anhydrous conditions using solid-phase derived gallium-68-acetylacetonate ([ 68Ga]Ga(acac)3) in a microwave-enhanced radiosynthesis. Commercial 68Ge/68Ga-radionuclide generators utilizing TiO2 to adsorb 68Ge(IV) (Obninsk-generators) were used. The initial aqueous generator eluate was transferred online onto a cation exchange resin and 68Ga was absorbed quantitatively. From this resin, 68Ga was eluted with different acetone-based, non-aqueous solvent systems. More than 95% of the generator-eluted 68Ga was obtained from the cation exchange resin with 600 μL of a 98% acetone/2% acetylacetone mixture providing n.c.a. [ 68Ga]Ga(acac)3 as labelling agent. Water-insoluble macrocyclic polypyrrole derivatives were chosen as model compounds for a proof-of-principle labelling of lipophilic compounds with 68Ga. Labelling of two different porphyrin derivatives, meso -tetraphenyl-porphyrin (Tpp) and (3-(1-hydroxyheptyl)deuteroporphyrin dimethylester (HHDPD) was performed in chloroform in a focused microwave synthesis system in yields of up to 90% within 5 min using phenol as co-ligand. Moreover, new co-ligands were investigated to be more effective and significantly less toxic than phenol. Among the phenol alternatives, gentisic acid (2,5-dihydroxy benzoic acid, DHB, 5 mg) emerged as the most useful, non-toxic phenol substitute. It facilitates reducing the load of co-ligand by 95%, while providing an increased labeling yield of 97%. 68Ga-labelled porphyrins may facilitate the medical application for molecular imaging via positron emission tomography.

Spectroscopic and biological studies of a novel synthetic chlorin derivative with prospects for use in PDT.

Photosensitizers with desirable combinations of chemical, photophysical and biological properties are essential for improving the efficacy of photodynamic therapy (PDT) against various cancers. Chlorins seem to be promising candidates for photodynamic therapy (PDT) owing to their photophysical properties. This paper reports spectroscopic and biological properties of a novel synthetic chlorin derivative. Cytotoxicity, phototoxicity as well as subcellular localization of the novel derivative was studied using Lewis lung carcinoma cultured cells (LLC). In the examined concentration range no significant cytotoxic effects were found but high phototoxicity was observed. Confocal laser scanning microscopy demonstrated that the compound, upon entering cells, was localized in the perinuclear cytoplasm of LLC cells. Using fluorescent microscopy we investigated the impact of PDT based on the novel compound upon cytoskeleton and DNA structure of LLC cells. Our results indicate that liposomes are effective in transferring the chlorin photosensitizer into the studied cells, leading to their high photosensitization, whereas the non-carrier delivery mode (i.e., DMSO) is rather useless for such purposes.