The phase transitions of 4-aminopyridine-based indolocarbazoles: twinning, local- and pseudo-symmetry.

ABSTRACT: The phase transitions and polymorphism of three 4-aminopyridine-based indolocarbazole analogues are analyzed with respect to symmetry relationships and twinning. Seven polymorphs were structurally characterized using single-crystal diffraction. 5NICz (the indolo[3,2,1-jk]carbazole derivative with the C atom in the 5-position replaced by N) crystallizes as a P2₁/a high-temperature (270 K) polymorph and as a Pca2₁ low-temperature (150 K) polymorph. Even though their space-group symmetry is not related by a group-subgroup relationship, the local symmetries of both belong to the same order-disorder (OD) groupoid family. Both are polytypes of a maximum degree of order and are twinned by point operations of the other polytype. 2NICz (C atom in the 2-position replaced by N)

SUBMITTER: Kader T 

PROVIDER: S-EPMC6457041 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature