Synthesis and behavior of novel phthalocyanines possessing intramolecular crown ether bridges between their different aromatic rings for effective extraction multi metal inclusion

Novel Cu- and Co-phthalocyanines (7a–e, 8a, b) possessing intramolecular crown ether bridges between their different aromatic rings were successfully synthesized from the reaction of the corresponding bisphthalonitriles (6a–e) bearing polyethyleneoxy chains in the presence of CuCl and CoCl₂, respectively. As 1,8-diazabicyclo [5.4.0]-7-undecene (DBU) was used as a base in n-pentanol at reflux temperature for 30 h under N₂ atmosphere, these new phthalocyanines were found to be characteristic of satisfactory solubility in some of organic solvents, and showed strong absorption bands in ultraviolet and visible wave length region (λ_max=719–739 nm). Extraction experiment of metal chlorides (NaCl, KCl, MgCl₂, CaCl₂, CeCl₃, ZnCl₂, FeCl₃) in chloroform was carried out by using Cu-phthalocyanine (7b) bearing two intramolecular bridges with tri(ethyleneoxy) chains. Among these metal salts, 7b formed a complex (9b) with only FeCl₃, which showed a dark-red amorphous solid. Spectroscopic analysis of the complex (9b) indicated that original strong absorption bands near 738 nm characteristic for phthalocyanines completely disappeared, and new two strong bands appeared near 799–853 nm. FAB-MASS spectrum of the complex (9b) showed that new strong peaks came out in the region centered at m/z=1879 and 1881 besides original peaks in the region centered at 1488, which corresponded to molecular peak of the starting phthalocyanine (7b). These facts indicated that the complex (9b) included two molecules of FeCl₃ into the protonated crown ether bridges of the phthalocyanine skeleton. Furthermore, it was found that the complex (9b) was transformed to the original phthalocyanine (7b) quantitatively by treatment with triethylamine.