Theoretical study of the helical conformers and ECD spectra of 8-aminoquinoline polymers

Based on the molecular force field, the stable conformers of 8-aminoquinoline oligoamides containing chiral β-pinene have been searched. The stability of helical conformers is different when β-pinene connects with 8-aminoquinoline at the nitrogen terminal and carbon terminals. And β-pinene can form delocalized π-bonds at the C-terminal of oligoamides, which can improve the strength of absorption spectra of the CQn. [Display omitted] •The terminal chiral group mainly induces the helical selection of oligoamides.•Terminal conjugated bonds affect the strength of absorption spectra.•ECD spectra reflect the helical handedness of oligoamides.•The more repeat units oligoamides have, the fewer conformers are found. In this study, the helical conformers and absorption spectra of three types of 8-aminoquinoline oligoamides were studied. The stable conformers of these oligoamides connected with chiral β-pinene at their terminals were searched, and their dominant conformers and corresponding Boltzmann statistical weights were obtained. The excitation energy and oscillator strength of the dominant conformers were calculated, and the UV and electronic circular dichroism (ECD) spectra were also simulated. β-pinene can form delocalized π-bonds at the C-terminal, which results in a strong R band for CQn. Furthermore, the degree of polymerization also affected the strength of the absorption band for all the oligoamides.