Binary charge-transfer complexes using pyromellitic acid dianhydride featuring C-H⋯O hydrogen bonds.

Four binary charge-transfer complexes were made using pyromellitic acid dianhydride (pmda), those being pmda-naphthalene (1/1), CHO·CH, (I), pmda-fluoranthene (1/1), CHO·CH, (II), pmda-9-methyl-anthracene (1/1), CHO·CH, (III), and pmda-ethyl anthracene-9-carboxyl-ate (1/2), CHO·2CHO, (IV). All charge-transfer complexes show alternating donor and acceptor stacks, which have weak C-H⋯O hydrogen bonds connecting the donor and acceptor mol-ecules. In addition, complex (I) has ' = 1/2, complex (II) has a ' = 2 and complex (IV) has half mol-ecule of pyromellitic acid dianhydride in the asymmetric unit.