Selective crystal growth of polymorphs and crystal-to-crystal thermal phase transition of non-peripherally alkyl-substituted phthalocyanine and tetrabenzotriazaporphyrin

Selective crystal growth of polymorphs and crystal-to-crystal thermal phase transition of non-peripherally alkyl-substituted macrocycle molecules, such as octapentylphthalocyanine (C5PcH(2)), octahexylphthalocyanine (C6PcH(2)), and octahexyltetrabenzotriazaporphyrin (C6TBTAPH(2)) have been investigated. Two types of single crystals, called alpha-type and beta-type, were separately grown by controlling the recrystallization conditions, and the crystal structures were determined by single-crystal X-ray structure analysis. The irreversible crystal-to-crystal thermal phase transition from alpha-type to beta-type were observed by the differential scanning calorimetry and temperature-controlled X-ray structure analysis. The selective crystal growth of the alpha-type or beta-type and the irreversible crystal-to-crystal thermal phase transition have been discussed by taking the alkyl-substituent distribution into consideration.