Optical properties of polyimines: UV–vis and photoluminescence study of undoped and doped polymers in aprotic and protic solvents

The optical properties of polyimines (PAs) with structure containing aliphatic-aromatic and aromatic-aromatic moieties are reported. It is demonstrated that the photoluminescence (PL) spectra can be regulated over a wide range by variation in main chain structure and through protonation or intramolecular hydrogen bonding. By combining these two methods it is possible to precisely tune the emission spectra of PAs in the spectral range of 480-531 nm. Luminescent PA/1,3,5-benzenetricarboxamide sulfonic acid complexes were self-organizated from nonamphiphilic n-conjugated PAs, in DMA and in m-cresol solution. Solvatochromism is manifested in the PL spectra of the undoped and doped PAs. The emission spectra of doped PAs are blue or red shifted relative to the undoped one. Additionally, absorption (UV-vis) properties of the PAs before and after protonation with 1,3,5-benzenetricarboxamide sulfonic acid ('dopant I') were tested. We propose that the novel self-assembly is driven by the amphiphilicity of 1,3,5-benzenetricarboxamide sulfonic acid activated by protonation of PAs.