| Efficient luminescent fluorescent organic materials have attracted extensive attention due to their potential application values in several areas, such as sensors, storage devices, optical devices and photoelectronic devices. It is well-known that most of the fluorescent organic materials are practically utilised in the aggregate state, such as solid or thin film. However, many traditional fluorescent organic materials are highly emissive in their dilute solutions but become weakly luminescent when aggregated into condensed phase. This phenomenon is termed as aggregation caused quenching (ACQ) effect. Obviously, the ACQ effect is very disadvantageous to the practical application of fluorescent organic materials. Fortunately, in 2001, professor Tang's research group of Hong Kong University of Science and Technology reported an interesting aggregation-induced emission (AIE) phenomenon. These fluorescent molecules with AIE effect are hardly emissive or faintly emissive in their dilute solutions. Nevertheless, their emission efficiencies are largely increased when aggregated into condensed phase. Therefore, this discovery of AIE phenomenon is very significative for practical application of fluorescent organic materials. In addition, studies of stimuli-responsive fluorescent materials based on organic and organometallic compounds are considered to be quite important due to their potential practicability in some areas such as sensors and recording devices. Based on the above research background, it has great practical significance to design and synthesize new fluorescent molecules with AIE and stimuli-responsive characteristics.In this paper, we synthesized a series of highly aggregate state emissive and ultraviolet light-responsive fluorescent organic molecules via rational molecular design. In addition, we designed and synthesized a series of metal complexes with AIE and stimuli-responsive characteristics via introducing pentafluorophenyl gold(?) skeleton of rich nature into the units of fluorene or carbazole. Furthermore, we obtained a single-component white light-emitting gold(?) complex with high fluorescence quantum yield via delicate design. The main research contents are shown as following:1. Four fluorene-based fluorescent molecules containing formamide or fluorenone unit have been designed and synthesized. These target compounds have been characterized by 1H NMR spectroscopy, 13C NMR spectroscopy, mass spectrometry and elemental analysis. Their aggregation-induced behaviors were investigated by UV-Vis absorption and photoluminescence spectroscopies. The research results indicated that the target compounds I-1 and I-2 showed aggregation-induced fluorescence change property, and the target compounds I-3 and I-4 exhibited aggregation-induced emission enhancement (AIEE) property. Their thin-film luminescence and solid-state luminescence behaviors were systematically investigated by thin-film fluorescence and solid-state fluorescence spectroscopies. The research results indicated that four target compounds showed strong luminescence in thin-films and in the solid state. This research provides a new idea for the design of highly aggregate state emissive fluorene-based fluorescent organic molecules.2. Five gold(I) complexes with different numbers of fluorene units have been designed and synthesized. These target complexes have been characterized by 1H NMR spectroscopy,19F NMR spectroscopy and elemental analysis, and the target complex ?-1 was confirmed by X-ray single crystal diffraction. The aggregation-induced behaviors of five target gold(I) complexes were investigated by UV-Vis absorption and photoluminescence spectroscopies. The research results indicated that the target complex II-3 showed aggregation-induced emission (AIE) property, and the target complexes ?-2 and ?-4 showed aggregation-induced fluorescence change property. In addition, the target complexes ?-1 and ?-5 exhibited aggregation-induced white light-emitting property, and both their solids and thin-films showed single-component white light-emitting behavior. The thin-film fluorescence quantum yield of the target complex ?-1 is as high as 65.42%. This research provides a new idea for the design of single-component white light-emitting materials with high fluorescence quantum yield.3. Three fluorene-based fluorescent molecules with different numbers of alkyl chains have been designed and synthesized. These target compounds have been characterized by H NMR spectroscopy, 13C NMR spectroscopy, mass spectrometry and elemental analysis, and the target compound ?-1 was confirmed by X-ray single crystal diffraction. The ultraviolet light-responsive behaviors of three target compounds were studied by photoluminescence spectroscopy. The research results indicated that the irradiation of ultraviolet light could change the fluorescence colors of three target compounds in solution aggregate state, and their fluorescence colors changed from blue to white, and finally to green or yellow-green with the increase of ultraviolet light irradiation time. Ultraviolet light response of the target compound ?-2 was the most sensitive among them. This research provides a new idea for the design of ultraviolet light-responsive pure hydrocarbon fluorescent organic molecules.4. Four fluorene-based gold(?) complexes have been designed and synthesized. These target complexes have been characterized by 1H NMR spectroscopy, 19F NMR spectroscopy and elemental analysis, and the target complex ?-4 was confirmed by X-ray single crystal diffraction. The aggregation-induced and mechanochromic behaviors of four target gold(I) complexes were investigated by UV-Vis absorption, photoluminescence, and solid-state fluorescence spectroscopies. The research results indicated that the target complexes ?-2 and ?-3 showed aggregation-induced emission (AIE) property, and the target complex ?-1 showed aggregation-induced emission (AIE) and mechanochromism characteristics. In addition, the target complex ?-4 exhibited aggregation-induced emission (AIE), mechanochromism, and crystallization-induced emission enhancement characteristics. This research provides a new idea for the design of fluorene-based multifunctional luminescent metal complexes.5. Six carbazole-based mono-and dinuclear gold(I) complexes have been designed and synthesized. These target complexes have been characterized by 1H NMR spectroscopy,19F NMR spectroscopy and elemental analysis, and the target complexes V-1, V-2 and V-6 were confirmed by X-ray single crystal diffraction. The research results of UV-Vis absorption and photoluminescence spectroscopies indicated that the six target gold(I) complexes all showed obvious aggregation-induced emission (AIE) property. The research results of solid-state fluorescence spectroscopy indicated that the six target gold(I) complexes exhibited three distinct types of mechanofluorochromic behaviors. This research provides a new idea for the design of carbazole-based metal complexes with aggregation-induced emission (AIE) and mechanofluorochromic characteristics.6. Seven carbazole-based mononuclear gold(I) complexes with alkyl chains of different lengths have been designed and synthesized. These target complexes have been characterized by 1H NMR spectroscopy, 19F NMR spectroscopy and elemental analysis, and the target complexes VI-1, VI-3, VI-4, VI-5 and VI-7 were confirmed by X-ray single crystal diffraction. The research results of UV-Vis absorption and photoluminescence spectroscopies indicated that the seven target gold(I) complexes all showed obvious aggregation-induced emission (AIE) property. The research results of solid-state and thin-film fluorescence spectroscopies indicated that the seven target gold(?) complexes with alkyl chains of different lengths showed diversified solid-state fluorescent colors. Upon gentle grinding, the solid-state emission colors of these target complexes all turned to the green. Furthermore, after these ground solid powders were treated with dichloromethane vapor, these ground solid powders could revert to their original unground emission colors. In addition, the seven target gold(I) complexes all showed thermochromism and vapochromism characteristics. This research provides a new idea for the design of carbazole-based metal complexes with aggregation-induced emission (AIE) and multistimuli-responsive characteristics. |
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