Synthesis Of Small Molecule Fluorescent Light Materials (phosphorus) And Its Application

Due to their advantages such as small volume, high quantum efficiency, easy synthesis and modification, small-molecule fluorescent (phosphorescent) materials attract increasing number of attentions. There are two main types of luminescent materials: organic fluorescent dyes and phosphorescent complexes. According to their own character, these materials are applicable in OLED, bio-imaging, chemosensor and so on. In this thesis, we focus on synthesis of three types of luminescent compounds and developing their application.1. Multisignal chemosensor for Cr³⁺ based on rhodamine BOwing to their excellent spectroscopic properties of visible wavelength excitation and emission profiles, large molar extinction coefficients, and high fluorescence quantum yields, rhodamine derivatives are ideal materials for fluorescent probes. In this work, an 8-hydroxyquinoline group as a conjugated moiety and a ferrocene were introduced to the rhodamine derivative FD7. As designed, FD7 could selectively recognize Cr³⁺ over other metal cations (including Hg²⁺), with suitably large variations in absorption, fluorescence emission, and electrochemical parameters. This is attributed to the complexation of FD7 with Cr³⁺ that induces the delocalization in the xanthene moiety of the rhodamine. Furthermore, FD7 can be used as a fluorescent probe for monitoring Cr³⁺ in living cells by means of confocal laser scanning microscopy experiments.2. Phosphorescent chemodosimeter for cysteine(Cys) and homocysteine(Hcy) based on platinum(II) complexesThiols are crucial for human body, because of its function in balancing redox reactions in biological system. As two of most significant thiols, cysteine and homocysteine are especially important for physiological equilibrium. Deficiency of Cys would lead to many diseases, such as hematopoiesis decrease, leucocyte loss, and psoriasis, while Hcy is a risk factor for cardiovascular and Alzheimer's disease.Due to high quantum efficiency, large Stocks shift, narrow emission peak and long life-time, platinum complexes as phosphorescent signal groups are suitable for chemosensors. Based on the selective reaction of the aldehyde moiety withβ- andγ-aminoalkylthiol groups to form thiazolidines, we synthesized Pt(phen)(C=CC₆H₄CHO)₂ for detecting cysteine/homocysteine. Upon addition of homocysteine/cysteine to its acetonitrile-water solution, an evident luminescent color variation from green to orange was observed.3. Aggregation-induced phosphorescent emission of iridium(III) complexesDue to the heavy atoms effect caused by central Iridium atom, iridium complexes have strong spin orbit coupling. Accordingly, the intersystem crossing efficiency from singlet to triplet has been improved as well as the transfer efficiency from T₁ to S₀. Besides, because of great Metal to Ligand Charge Transfer (MLCT) character, iridium complexes have excellent photophysical property.In this work, one novel aggregation-induced phosphorescent emission (AIPE) was observed for iridium (III) complexes withβ-diketone ligands. In order to explain this interesting phenomenon, several iridium (III) complexes with different restricted (even fixed) intramolecular rotational motion were synthesized. Based on the photophysical data, X-ray crystal diffraction experiment and theoretical calculation, we confirmed that theπ-πstacking of adjacent pyridyl rings of ppy ligands played a key role in AIPE process.