Self-assembly of N,N '-bis(2-tert-butylphenyl)pyromellitic diimide and phenols or indoles into a piled sandwich structure. Networks constructed by weak host-host and strong host-guest interaction in the clathrate compounds

A novel clathrate host, N,N'-bis(2-tert-butylphenyl)pyromellitic diimide (1 ), was designed to create a sandwich structure without using cyclophanes no r the acyclic compounds. In the host-guest crystal, the host molecule is sa ndwiched between two aromatic guest molecules. The inclusion experiment was performed by recrystallization of 1 from chloroform in the presence of the guest at room temperature to give the clathrate compounds. Phenols (phenol , p-cresol, alpha-naphthol, beta-naphthol, catechol) and indoles (indole, 3 -methylindole, 4-methylindole, 5-methylindole) were included in the clathra te compounds, and the host/guest ratio 1:2 was observed in all cases. To ex plain the mechanism of the self-assembly to the piled sandwich structure, X -ray analysis of the single crystals was performed in all cases. Further, c harge-transfer complexation, hydrogen bonding and dipole-dipole interaction were investigated using UV, IR, differential scanning calorimertry (DSC), and AM1 calculation. The order of the decomposition temperature related wel l with the order of the guest insertion. During the crystallization process , the packing of a guest with a small dipole moment smoothly proceeds and f orms a stable clathrate compound. However, a guest which has a large dipole moment generates large electrostatic repulsion in the networks and forms a n unstable clathrate compound.