The Structures of Macrocyclic Heterocyclophane Inclusion Complexes

Abstract

Crystal and molecular structures of (1:1) molecular complexes of N,N′,N″,N‴ -tetramethyl–2,11,20,29-tetraaza [3.3.3.3] paracyclophane (1) with CHC1₃, CH₂C1₂, CH₃CN and CO₂ are reported. The macrocycle has square-box structure, giving hydrophobic cavity surrounded by four benzene rings. The guest molecules are included in the cavity. The uncomplexed 1 was found to have a rectangular form, indicating large conformational flexibility of. 1. In solution, 1 is achiral because rapid R⇌S interconversion, but in solid, the macrocyclic conformation is frozen as,“R”-conformer or “S”conformer. The macrocycles with the same chirality are stacked along b-axis to form chiral molecular columns, “R”-columns or “S”-columns. Complexes of 1 crystallize differently depending on the guest molecules. “R”-columns (“S”-columns) packed along a-axis produce “R”-layers(“S”-layers),which are further packed along c-axis using “R”-layer to “R”-layer contact (RR) or SS and RS or SR. The crystals of 1 • CHC1₃ are formulated as --RRR-- =[R]_n(Type I, chiral) and those of 1 • CH₃CN or 1 • C02 and l • CH₂CI₂ are represented by [RS]n(Type IIA, racemic) and [RRSS]_n(Type IIB, racemic), respectively.