title: Small Iminocoumarin Derivatives as Red Emitters: From Biological Imaging to Highly Photoluminescent Non-doped Micro- and Nanofibres.
abstract: The fluorescence properties of four derivatives of 3-thienyl-2-(N-dicyanovinyl)iminocoumarin, bearing a diethylamino group in the 7-position or a methoxy group in the 6, 7 and 8 positions, were compared in solution and in the solid state. The 7-diethylamino derivative was strongly fluorescent in various solvents, with marked solvatochromism. Its fluorescence was quenched by aggregation. In contrast, the methoxy derivatives were only moderately or weakly fluorescent in solution, but two of them were strongly photoluminescent in the crystalline state, owing to favourable molecular packing. The 6-methoxy derivative even exhibited spectacular crystallization-enhanced emission, examples of which are particularly rare for this type of dyes. Dyes were tested for biological use. The 7-diethylamino derivative led to particularly strong fluorescence staining of the cytoplasm of HCT-116 colon cancer cells. No fading was observed over prolonged illumination by the microscope light beam, but a phototoxic effect was detected. The use of the dyes as red-emitting materials was also investigated. Using easy-to-implement preparation methods, the compounds self- assembled to give one-dimensional nano- and microsized particles, including millimeter-long microfibres that exhibited clear wave-guiding properties. This study shows the value of these low molecular-weight molecules for the preparation of new orange and red-emitting fluorescent materials based on totally pure dye.
authors: Laboratory of Applied Chemistry HCGP, Faculty of Science, University of Sfax, 3038 Sfax (Tunisia); CNRS, ITAV-USR 3505, 31106 Toulouse (France), Postal address: ITAV (Advanced Technology Institute for Life Sciences), CNRS USR 3505,1 place Pierre Potier, Oncopôle, BP 50624, 31106 Toulouse Cedex 1 (France); Université de Toulouse, ITAV-USR 3505, 31106 Toulouse (France); CNRS, IMRCP-UMR 5623, 31062 Toulouse (France); Université de Toulouse, IMRCP-UMR 5623, 31062 Toulouse (France).
authors: Kacem
authors: K
authors: Khemakhem
authors: Marine
authors: M
authors: Soulié
authors: Rémy
authors: R
authors: Brousses
authors: Houcine
authors: H
authors: Ammar
authors: Souhir
authors: S
authors: Abid
authors: Suzanne
authors: S
authors: Fery-Forgues
keywords: crystal structure determination; fibers; fluorescent probes; imaging agents; optical properties