Synthesis and Characterization of some Photo-CORM and Photosensitizers

Sammanfattning: It is well known that Carbon monoxide is a toxic and hazardous gas, but during recent years it has been proven that using a controlled concentration, carbon monoxide can in fact be used as a therapeutic agent, and can contribute to decrease malaria, treat cardiovascular and lung diseases and potentially even treat cancer, among other things. The main problem in using carbon monoxide directly is the fact that it is not trivial to control the volume of gas inhaled, compromising its use as a therapeutic agent. Much effort has been made to synthesize molecules that can release carbon monoxide, so-called CORMs. The release of the carbon monoxide present in these molecules can occur in different ways: a) exchanging the carbon monoxide with solvent (e.g. water). Although this is an easy and controlled method to release a known quantity of carbon monoxide, it is not possible to guarantee the time and tissue the CO is released. b) triggering the release of carbon monoxide, for example by light exposure (Photo-CORMs). This can be an efficient method, since metal carbonyls are well known as photosensitive systems. Two Photo-CORMs complexes, Re(aaz)(CO)3]Cl (aaz = 6-amino-6-methylperhydro-1,4-diazepine) and [Re(tacn)(CO)3]Cl (tacn = 1,4,7-triazacyclononane), were synthesized, fully characterized and tested for their ability to release carbon monoxide when exposed to light radiation. By determining the change in oxidation potential through square wave electrochemistry, as well as UV- and IR-spectra, there was enough proof to conclude that the complexes release at least 2 equivalents of carbon monoxide per Photo-CORM when radiated by UV light. Four new complexes, containing photosensitizers were also synthesized and characterized [Ru(Me2bpy)2Cl2] (bpy = 2,2’-bipyridine) , [Ru(phen)2Cl2] (phen = 1,10-phenanthroline), [Cu(Me2-bpy)2]BF4 (4,4’-dimethyl-2,2’-bipyridine) and [Fe(η5-C5H4CHO)(η6-C6H6)]PF6 ((η5-C5H4CHO)(η6-C6H6) = η6-benzene,η5-cyclopentadienyl). All the four complexes absorb IR radiation and excite the Photo-CORM through triplet energy transfer. The IR spectroscopy showed that all photosensitizers were formed, since there were displacements of the bands and formation of new bands.