Effect of binding mode on the photoluminescence of CTMA–DNA doped with (E)-2-(2-(4-(diethylamino)styryl)-4H-pyran-4-ylidene)malononitrile

Purified natural DNA extracted from Salmon sperm can only be dissolved in water; it is not soluble in any other organic solvent. Therefore, in this study, the structure of DNA was modified and its solubility was changed. The preparation of organic-soluble DNA was carried out by precipitating the purified DNA in water with the cationic surfactant cetyltrimethylammonium chloride (CTMA). The resulting DNA–lipid complex shows good solubility in alcohol, which allows the fabrication of thin films for studying the photophysical properties of DNA in a solid state. The absorption and photoluminescence (PL) behaviors of CTMA–DNA and polymethylmethacrylate (PMMA) doped with (E)-2-(2-(4-(diethylamino)styryl)-4H-pyran-4-ylidene)malononitrile (DCM) were investigated. In addition, different PL spectral behaviors with differing concentrations of DCM in two different host materials were observed. These behaviors were explained by a mechanism based on intercalation or groove binding of fluorescent dye into the base pairs or aliphatic side-chain moieties of CTMA–DNA.