Synthesis and characterization of new chromium and aluminum metalloporphyrins in route to water-soluble buckminsterfullerene radical anion salts

[摘要] Five new metalloporphyrins, $m lbrack Alsp{III} (TPPCM)Clbrack,$ $m lbrack Alsp{III} (TPPCN)Clbrack,$ $m lbrack Alsp{III} (TPPC)Clbrack,$ $m lbrack Crsp{III} (TPPCM)Clbrack,$ and $m lbrack Crsp{III} (TPPCN)Clbrack,$ have been synthesized and characterized as a first step toward the bulk synthesis of water-soluble C$sb{60}sp{.-}$ salts. According to a literature report, Cr$m sp{II}$(TPP) and (Al$m sp{III}$(TPP)$sp{.-}brack$ (TPP$sp{2{-}}$ = tetraphenylporphyrinato) reduce C$sb{60}$ to C$sb{60}sp{.-}$ under proper solvent conditions to form an insoluble $m lbrack Crsp{III}(TPP)bracksp+(Csb{60}sp{.-})$ or (Al$m sp{III}$(TPP)$bracksp+$(C$sb{60}sp{.-})$ salt. Here it is proposed to derivatize these Cr$m sp{II}$ and Al$m sp{III}$ tetraphenylporphyrins with substituents on the phenyl rings to produce water-soluble $m lbrack Crsp{III} (TPPR)bracksp+(Csb{60}sp{.-})$ and $m lbrack Alsp{III} (TPPR)bracksp+(Csb{60}sp{.-})$ salts. Initial electrochemical data for precursor $m lbrack Alsp{III} (TPPCM)Clbrack,$ $m lbrack Alsp{III} (TPPCN)Clbrack,$ $m lbrack Alsp{III} (TPPC)Clbrack,$ $m lbrack Crsp{III} (TPPCM)Clbrack,$ and $m lbrack Crsp{III} (TPPCN)Clbrack$ compounds suggest that adding water-solubilizing substituents does not interfere with the electron transfer between the reduced Al$m sp{III}$ and C$m sp{II}$ metalloporphyrins and C$sb{60}.$ Hence, there is potential to produce bulk amounts of water-soluble C$sb{60}sp{.-}$ by this method. The radical anion has 150 A$sp2$ of paramagnetic surface area (S = 1/2), and possible utility as a new magnetic resonance imaging contrast agent.

[发布机构] Rice University

[效力级别] chemistry