Determination of the structure of 2(benzene-1,3,5-tricarboxylic acid)center dot 1.5(pyrene)center dot 2(methanol) and comparison with that of 2(benzene-1,3,5-tricarboxylic acid)center dot pyrene center dot 2(ethanol)

The structure of the title methanol complex (P (1) over bar, Z = 2) has bee n determined and compared with that of the title ethanol complex (C2/c, Z = 8) using published data. Both complexes have layer structures, the (essent ially planar) layers being constructed from rings of six TMA molecules, hyd rogen bonded through four 'carboxyl dimers' and two 'interrupted dimers', w here methanol (ethanol) is included in the R-4(4)(12) (graph set) ring. The packing of the layers differs in the two complexes, leading to different t hree-dimensional structures. In the methanol complex, one pyrene molecule i s located within the layer and the other, at a centre of symmetry, between the layers in one type of interlayer space, while the methyls of methanol p rotrude into the other type of interlayer space. In the ethanol complex, th e superpositioning of the layers is such that two types of stack are formed ; one of these is mixed, containing pyrene and one of the independent TMA m olecules in alternating sequence, while the other stack contains only the s econd type of TMA. Spectroscopic study is needed to establish whether the p artial mixed stack arrangement in the crystalline ethanol complex implies d onor-acceptor interaction.