Formation of infinite grids with chiral square compartments by self-assembly of achiral 1,1 '-biphenyl-2,2 ',6,6 '-tetracarboxylic acids. Effect of 4,4 '-substitution on the grid stacking

The achiral 1,1 ' -biphenyl-2,2 ' ,6,6 ' -tetracarboxylic acid as well as i ts 4,4 ' -dibromo and 4,4 ' -dinitro derivative self-assemble in crystal un der formation of a two-dimensional grid set up from hydrogen-bonded cyclote trameric compartments which are individually chiral (D-4 symmetry). The rou ghly square cavities (ca 5.6 Angstrom) of individual compartments partly ac commodate the perpendicularly oriented benzene rings of the neighbouring gr id, in dependence on the nature of the 4,4 ' -substituents. As a consequenc e, the grids are stacked in a staggered (nonconcatenated) manner.