Supramolecular Chiral Self-assembly Of Perylene Derivatives

Optically active supramolecular assemblies consisted of achiral substances are possibly related to the origin of chirality or even life.Such aggregates have attracted considerable interest in not only chemistry but also materials science in applications such as molecular recognition,asymmetric catalysis and nanotechnology.The fundamental point of research in supramolecular chiral assemblies is how to choose the building blocks,which need to meet the requirements: 1)The noncovalent interactions between building blocks should be strong enough to form supramolecular assemblies;2)The building blocks should ensure the potential function after supramolecular system formed.Perylene is a kind of ?-conjugated system with excellent optoelectronic properties.Furthermore,there are multiple modifiable sites on the perylene core,and various perylene derivatives can be prepared by introducing different substituents to make the molecular structure more diversified,laying a foundation for construction of supramolecular structure.These characteristics make the perylene a good choice for chiral supramolecular assemblies.In this paper,two kinds of helical enantiomers(P,P)and(M,M)in perylene derivatives were selected,which usually exist as racemic species.By modification of perylene with acetanilide groups,the racemic molecules tended to form chiral supramolecular aggregates,with the help of dense intermolecular hydrogen-bonding interactions and external stimulus.The followings were the main results we have obtained:(1)Ortho-substituted tetrabromo-perylene quinone was prepared from3,6-dibromo-2,7-dihydroxy naphthalene by controlled intermolecular radical oxidative coupling.The ortho-tetrabromo-substituted perylene(Per-4Br)precusor was obtained by the chemical reduction of perylene quinone and bay-dietherylation.Ortho-and peri-function were conducted on the basis of Per-4Br.(2)Perylene derivatives were successfully prepared by introducing acetanilide groups to the ortho-and peri-positions,which showed a potential to form supramolecular assembly duo to possible intermolecular hydrogen-bonding interactions between each amide groups.To be noted,the racemic perylene derivatives mentioned above in acetone solution exhibited concentration-dependent self-assembly behavior,which clearly exhibited circular dichroic absorption and circularly polarized luminescence at high concentrations.(3)More amide groups will be introduced to the ortho-and the peri-position of perylene,for the purpose of amplification of supramolecular chirality,which possibly reveal the intrinsic mechanism of supramolecular chirality through achiral substrates.