NEW TEXAPHYRIN-TYPE EXPANDED PORPHYRINS

This paper presents the synthesis of several new Schiff-base type expa nded porphyrins. A dimeric, tetraazacyclodotetradecane-linked texaphyr in system has been prepared. It, as its gadolinium(III) adduct, displa ys a relaxivity in aqueous solution that is roughly 5 times higher tha n the benchmark texaphyrin monomer currently undergoing human clinical trials as a potential MRT enhancing and X-ray radiation sensitizing d rug. Polymeric gadolinium(III) texaphyrin species, derived from poly-l -lysine and a glycosylated poly-l-lysine, have also been prepared; the y too display greatly enhanced relaxivities. In work along different l ines, the synthesis of an ''expanded'' texaphyrin has been effected an d the construction of two ''three dimensional'' texaphyrin-inspired ta rgets accomplished. These latter define a new class of pyrrolic crypta nds.