Synthesis of multi-neopentoxy substituted and non-centrosymmetric phthalocyanines

A series of phthalonitriles substituted with neopentoxy groups in the 4,5-, 3,6- and 3,4,5,6-positions were synthesized, characterized and subsequently condensed to their corresponding phthalocyanines. The UV-Vis spectrum of the 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecaneopentoxyphthalocyanine was found to be more red shifted than any other hexadecaalkoxy substituted phthalocyanine reported in the literature thus far.

The development of a synthetic method toward the preparation of tetrasubstituted phthalonitriles consisting of amino-alkoxy and amino-thiol substituents is also described. This method involves the reaction of 3,4,5,6-tetrafluorophthaIonitrile with an amine to yield 4,5-diamino-3,6-difluorophthalonitrile. Further reaction of this compound with either, an alcohol or thiol afforded tetra substituted phthalonitriles. Self-condensation of these phthalonitriles was not possible, however, cross condensation reaction of these compounds with phthalonitrile afforded non-centrosymmetric phthalocyanines. In addition, a method for synthesizing a non-centrosymmetric phthalocyanine using monomeric and dimeric phthalocyanine intermediates was examined.

Furthermore, it was discovered that the ¹H NMR spectra of the neopentoxy substituted phthalocyanines displayed signs of restricted rotation. Thus, five of the neopentoxy substituted phthalocyanines were subjected to variable temperature ¹H NMR studies and their thermokinetic parameters were determined.