Synthesis And Photoelectric Properties Of D-π-A Fluorescent Molecules Based On Benzoselenadiazole And Indenophenalene

Among the diverse classes of organic π-systems, donor-π-acceptor(D-π-A) type organic compounds with excellent photoelectric propertieshave attracted an increasing interest due to low band gaps in recent years,and another fascinating advantage of such materials is that the πconjugation, band gap, and electro-optical properties can be effectivelytuned by judicious choice of the fluorophores, donor and acceptorsubstituents. As a result, some organic molecules have been developed asfluorophores in this kind of system for the fluorescent detection. In thisdissertation, the studies focused on the design, synthesis and applicationas fluorescent sensors of D-π-A fluorescent materials based onbenzoselenadiazole unit and indeno[2,1-a]phenalene unit.1. Synthesis and properties of D-π-A conjugated polymers based onbenzoselenadiazole unit.Four novel D-π-A polymers P-1-P-4based on benzoselenadiazolemoiety and phenyl, naphthyl or fluorene group via alkyne module werefirstly prepared by Sonogashira-Hagihara reaction of various diiodo arylcomounds with the key monomer4,7-diethynylbenzoselenadiazole. Theirphotophysical properties have been studied. The results indicate that thesepolymers display low band gaps and narrow orange-red or redfluorescence, which also implys they can be used as good fluorescentmaterials. And one of them, P-4, has been developed as a highly selectiveand sensitive chemosensor for Hg2+, and the fluorescence detection limitis as low as1.9×10-7mol L-1.2. Synthesis and photoelectric properties of novel D-π-A indeno[2,1-a]-phenalene-based derivativesA series of novel D-π-A indeno[2,1-a]phenalene derivatives includingelectron-donating or electron-withdrawing groups were prepared bySonogashira-Hagihara reaction of various arylacetylene with7-iodo-12-phenylindeno[2,1-a]phenalene which was synthesized by the a dominointramolecular electrophilic cyclization from peri-ethynylene naphthalene and I2. These compounds have large molar absorption coefficients in therange of400to600nm and low band gaps (1.78-2.09eV). And thefluorescent emission of indeno[2,1-a]phenalene derivative containingdimethyl amino group is correlated with solvent polarity andenvironmental acidity. These findings indicate that indeno[2,1-a]-phenalene-based molecule can be developed as an excellent fluorophorefor optoelectronic material applications.