Studies On The Design, Synthesis And Properties Of Novel Nitrogen-Containing Heterocycles-Based Conjugated Organic Compounds

Compared to inorganic photoelectrical materials, organic photoelectrical materials have the advantages of wide varieties, diversity of properties, being designed and modified easily. Designing and synthesis of organic molecules with excellent photoelectrical properties attracted intensive attention in the development of functional materials. In this thesis, three novel series of conjugated organic molecules with nitrogen-containing heterocycles, including pyridine, imidazole or both of them, have been designed and synthesized. Their UV absorption, fluorescence emission spectra and thermal stability were studied.A new type of pyridine derivatives with electron withdrawing group were synthesized using microwave-assisted method. Based on the withdrawing group, a novel series of typical D-π-A conjugated organic molecules were synthesized by Horner-Wadsworth-Emmons (HWE) reaction. Their fluorescence emission spectra indicate the molecule intramolecular charge transfer properties. The target compounds show excellent thermal stability, and their thermal decomposition temperature above 310oC.2-(4-Formylphenyl)phenanthroimidazole was synthesized by the facile one-step condensation reaction under microwave in high yield and studied as a anion fluorescence probe. The probe exhibits a high selectivity and sensitivity for fluoride ion. The remarkable color changes of the solution caused by deprotonation of N-H on the imidazole moiety with fluoride anion make the probe become a naked-eye detection for fluoride anions. The 1H NMR titration demonstrated the deprotonation mechanism.A novel series of conjugated organic molecules containing both imidazole and pyridine heterocycles were synthesized and the typical D-π-A conjugated organic molecules were formed by introducting electron donation groups on the imidazole moiety, and introducting electon withdrawing groups on the pyridine moiety. Their UV absorption, fluorescence emission spectra show that the compounds have the large Stokes shift and intramolecular charge transfer properties. The thermogravmetric analysis results reveal excellent thermal stability.The central cores of the two types of star-shaped molecucles were synthesized by microwave-assisted synthesis method or milling reactions, and the star-shaped molecules with three or four substituted imidaziole arms were synthesized by cyclization reactions. Their UV absorption, fluorescence emission spectra and thermal stability were studied, and the thermogravmetric analysis results indicate excellent thermal stability with decomposition temperature of above 280 oC.Three novel series of conjugated organic molecules containing imidazole and pyridine heterocycles were designed and synthesized, their UV absorption, fluorescence emission spectra and thermal stability were studied. The results indicate their charge transfer properties and excellent thermal stability and lay a foundation for photoelectrical materials development.