Crown ethers porphyrazines

Crown ethers with mixed donor sets of soft sulfur and hard oxygen heteroatoms selectively ligate heavy metal ions such as mercury and silver. Porphyrazines with thia-oxo crown units appended to the periphery were published simultaneously by Hoffman and co-workers (25) and by Nolte and co-workers (26, 27). 

Oxa-crown porphyrazines (21) were synthesized by the Mg(II) template cyclization of crown ether derivatives of dithiomaleonitrile and shown to possess ligation of eight Ag(I) ions by utilizing both the crown ether and meso-pocket coordination sites [95AG(E)2020]. An improved preparation and the coordination chemistry with Ag(I) of oxa-crown derivatives of dithiomaleonitrile have been reported [95IC2300]. 

Hoffman et al. have reported the synthesis of tetrakis-, tris-, and monothiacrown ethers containing a tetra-azaporphyrin unit 139-152. The first porphyradine crown ethers were prepared by the Mgz+ template cyclization of the appropriate crowned derivative of dithiomaleonitrile 32 and 33 to afford 139 and 143, respectively, in ca. 35% yields. Treatment of 139 and 143 with trifluoroacetic acid provided the metal-free porphyrazines 140 and 144, respectively. Subsequent reaction with Ni(OAc)2 or Cu(OAc)2 quantitatively produced 141, 142, 145, and 146 (Scheme 21). 

They have also prepared mono- 147-149 and tris-crown ethers 150-152 containing the tetraazaporphyrin unit. Singly crowned porphyrazine 147 was prepared by the reaction of >15 equiv of 1,2-dicyanobenzene and 1 equiv of 33 under classic Linstead macrocyclization conditions. On the other hand, tris-crowned porphyrazine 150 was prepared by the reaction of 3 equiv of 32 and 1 equiv of l,2-dicyano-l,2-bis(l 1-hydroxyundecylthio)ethylene. Rapid complexa-tion of Ag+ was observed for 147-149, with weaker complexation of Hg2+ and Na+ observed only by MS. There was... 

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