Synthesis of 2,3,9,10,16,17,23,24-Octaalkynylphthalocyanines and the Effects of Concentration and Temperature on Their 1H NMR Spectra

The syntheses of 3,4- and 4,5-diiodophthalonitriles are described. Coupling of the latter compound with Pd(PPh3)2Cl2 and 1-octyne, 1-heptyne, 1-hexyne, 1-pentyne, and 3,3-dimethyl-1-butyne gave a series of 4,5-dialkynylphthalonitriles. Hydrogenation of 4,5-bis(1-pentynyl)phthalonitrile and 4,5-bis(3,3-dimethyl-1-butynyl)phthalonitrile gave 4,5-dipentylphthalonitrile and 4,5-bis(3,3-dimethylbutyl)phthalonitriles. Condensation of the dialkynylphthalonitriles with lithium 1-pentoxide in 1-pentanol gave 2,3,9,10,16,17,23,24-octaalkynylphthalocyanines, while intervention of the intermediate dilithium phthalocyanines with zinc acetate gave the related zinc(II) phthalocyanines. 1H NMR spectroscopy of these octaalkynylphthalocyanines exhibited large chemical shifts (1−2 ppm) of the internal and aromatic protons at concentrations ranging from 10-2 to 10-5 M and at temperatures from 27 to 147 °C. The effects of aggregation phenomena are discussed. The importance of reporting concentration and temperature values for NMR spectra of phthalocyanines is stressed.