Optical properties of N-(1H-indol-2-ylmethylidene)-4-methoxyaniline

摘要

The intramolecular hydrogen bond is important phenomenon which controls molecularisomerization and induces excited state intramolecular proton transfer (ESIPT).Indole,which is useful compound to derive pharmaceuticals and biological compounds,canfunction as a hydrogen donor of hydrogen bonding because of its high acidity of N-H.Introduction of a hydrogen acceptor on the 2 position of indole form five to sevenmembered intramolecular hydrogen bond.In this study,N-(1H-indol-2-ylmethylidene)aniline (InP,Figure 1) derivatives were synthesized.The nitrogen atom ofan imine serves as a hydrogen acceptor and five-membered intramolecular hydrogen bond isconstructed.Since indole is an electron rich heterocyclic aromatic ring,the highest occupiedmolecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) would bedistributed on indole ring and phenyl ring,respectively.It indicates that the electron densityof two nitrogen atoms connected through the intramolecular hydrogen bond would inverseby electron transition from HOMO to LUMO.Thus ESIPT would occur by light irradiation.The basicity of a hydrogen acceptor affects the proton transferring process.In order toenhance the basicity of the hydrogen acceptor nitrogen atom of InP,methoxy group,as anelectron donating group,is introduced at a para-position of phenyl moiety (InOM,Figure1).