New nitrogen- and sulfur-appended porphyrazines: Syntheses and spectroscopic investigations

The syntheses and isolation of unsymmetrical porphyrazines (pz's) bearing two, four and six bis(dimethylamino) functionalities at the beta carbon atoms has been achieved via the base-catalyzed cross condensation of 1,2-dicyanobenzene and bis(dimethylamino)maleonitrile. Investigation of the new macrocycles by cyclic voltammetry revealed that each may be readily oxidized, and that the value of the first oxidation potential decreases significantly as the number of peripheral amino groups is increased. The X-ray structures of porphyrazines 2.2b, 2.3a, and 2.5a are also presented. To the best of our knowledge, the structure of 2.3a represents the first of a porphyrazine having a " cis" configuration.; New derivatives of diaminomaleonitrile, in which both the amine nitrogen atoms have been functionalized with removable protecting groups, have been prepared as direct precursors to primary aminoporphyrazines. Alkylation of the amines with triphenylmethyl (trityl) chloride or 4,4'-dimethoxytrityl chloride proceeds smoothly and in good yields. Protection of the amines as sulfonamides, trimethylacetamides, or tert-butyl carbamates proceed in lower yields. Neither of the trityl derivatives successfully gave the corresponding porphyrazines when subjected to base-catalyzed cyclization conditions. The very poor overall yield of the bis(sulfonamide) made cyclization attempts impractical and therefore none were attempted. Mixed cyclizations to give unsymmetrical bis(trimethylacetamide)- and bis(tert-butylcarbamate)-appended porphyrazines proceeded in modest yields. Subsequent attempts to hydrolize the trimethylacetamides to give the desired primary porphyrazinediamines were unsuccessful. Treatment of the bis(tert-butylcarbamate) with trifluoroacetic acid at 0° successfully removed one BOC group from the pz. The same reaction at ambient temperature afforded unidentified oligomerization products.; Finally, we describe the complete synthesis and characterization of a new family of peripherally-functionalized porphyrazines with four, three, or two (in a trans conformation) bis[thioethoxy(ethoxy)ethanol] moieties appended at the beta-carbon atoms. These "polyetherol" groups serve as weak exocyclic binding sights for a number of metal ions and provide solubility of the pz's in low molecular-weight alcohols and water. The modified porphyrazines exhibit dramatic changes in the visible region (both absorbance and fluorescence) in response to treatment with Ag +, Pb2+, Cd2+, Cs+, and Ni2+ in solution. Such properties make these compounds intriguing candidates for application in chemical sensors.