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

Abstract

The achiral 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid as well as its 4,4'-dibromo and 4,4'-dinitro derivative self-assemble in crystal under formation of a two-dimensional grid set up from hydrogen-bonded cyclotetrameric compartments which are individually chiral (D4 symmetry). The roughly square cavities (ca 5.6 Å) of individual compartments partly accommodate the perpendicularly oriented benzene rings of the neighbouring grid, in dependence on the nature of the 4,4'-substituents. As a consequence, the grids are stacked in a staggered (nonconcatenated) manner.