Insight into the strong aggregation-induced emission of low-conjugated racemic C6-unsubstituted tetrahydropyrimidines through crystal-structure-property relationship of polymorphs.

ABSTRACT: Racemic C6-unsubstituted tetrahydropyrimidines (THPs) are a series of fluorophores with a strong aggregation-induced emission (AIE) effect. However, they do not possess the structural features of conventional AIE compounds. In order to understand their AIE mechanism, here, the influences of the molecular packing mode and the conformation on the optical properties of THPs were investigated using seven crystalline polymorphs of three THPs (1-3). The racemic THPs 1-3 have low-conjugated and highly flexible molecular structures, and hence show practically no emission in different organic solvents. However, the fluorescence quantum yields of their polymorphs are up to 93%, and the maximum excitation (λ_ex) and emission (λ_em) wavelengths of the po

SUBMITTER: Zhu Q 

PROVIDER: S-EPMC5667501 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature