Binary and ternary charge-transfer complexes using 1,3,5-tri-nitro-benzene.

Three binary and one ternary charge-transfer complexes have been made using 1,3,5-tri-nitro-benzene, viz. 1,3,5-tri-nitro-benzene-2-acetylnaphthalene (1/1), C6H3N3O6·C12H10O, (I), 1,3,5-tri-nitro-benzene-9-bromo-anthracene (1/1), C14H9Br·C6H3N3O6, (II), 1,3,5-tri-nitro-benzene-methyl red (1/1), C15H15N3O2·C6H3N3O6, (III) (systematic name for methyl red: 2-{(E)-[4-(di-methyl-amino)-phen-yl]diazen-yl}benzoic acid), and 1,3,5-tri-nitro-benzene-1-naphthoic acid-2-amino-5-nitro-pyridine (1/1/1), C6H3N3O6·C11H8O2·C5H5N3O2, (IV). All charge-transfer complexes show alternating donor and acceptor stacks, which have weak C-H⋯O hydrogen bonds perpendicular to the stacking axis. In addition, complex (IV) is a crystal engineering attempt to modify the packing of the stacks by inserting a third mol-ecule into the structure. This third mol-ecule is stabilized by strong hydrogen bonds between the carb-oxy-lic acid group of the donor mol-ecule and the pyridine acceptor mol-ecule.