| Methamphetamine ?MAPA, also called "ice"?, which is a kind of clear crystal, is a new type of drugs. Smoking MAPA can stimulate and excite people's nerve. Long-term use of MAPA can lead to insanity and paranoid schizophrenia, organic brain syndrome, hypertension, cerebral stroke and etc. The number of drug addicts has a continuous growth in China. According to statistics, there have been 2.955 million drug users by the end of 2014. However, the actual number is almost 14 million. Therefore, it is urgent to develop rapid, sensitive and reliable methods to detect MAPA. Among the existing methods, fluorescence methods possess a number of advantages, such as great sensitivity, high selectivity, abundant signals, etc. Compared to other fluorescent compounds, perylene bisimide derivatives ?PBIs? have several advantages:?1? high molar extinction coefficient (104 L·mol-1 · cm-1) contributed to strong light gathering ability; ?2? because of the two anhydride structures, PBIs are strongly electron deficient and are responsive to electron-rich compounds; ?3? PBIs possess high fluorescence quantum yield and good photochemical stability. Based on these advantages, fluorescent sensors derived from PBIs show attractive application prospects.It is known that PBIs can't dissolve well, which limits the modification and derivatization. Introducing suitable functional groups can not only enhance the solubility of PBIs, but also endow them with abundant assembly behavior. Cholesterol, which is a natural compound, is commonly used for creation of supra-molecular building blocks due to its rigid skeleton, several stereogenic centers and strong tendency to form aggregates via van der Waals interaction. Meanwhile, it is anticipated that introduction of long alkyl chains can reduce intermolecular aggregation behavior and is helpful to adjust assembly behavior of PBIs. Based on the above discussion and the research progress in our lab, two fluorescent sensors were designed and fabricated by using PBI as the core structure and cholesterol and alkyl chains as functional units, respectively. In detail, three chapters were listed in this dissertation.In chapter one, several parts are elaborated including research progress of PBIs, PBIs-based fluorescent sensors, electrochemical sensors and other sensors. Specifically, PBIs are widely used to develop for film sensor of organic amines during the sensing process of PBIs. Therefore, it is expected to fabricate several film sensors in which PBI is employed as a recognition unit and cholesteryl units or long alkyl chains are introduced to enhance solubility and assembly behavior, to realize the sensitive detection of Methyl-phenethylamine ?MPEA?.In chapter two, a PBI derivative ?PDC? with two cholesteryl units linked by two long alkyl chains in the imide positions was designed and synthesized. And it was characterized by 1H NMR, FT-IR, MS and elemental analysis. Solvent effect indicated that PDC possesses favorable solubility in chloroform and aggregates in polar solvents. Chloroform was used as the good solvent in all the three cases, while ethanol ?Film 1?, n-propanol ?Film 2? or acetone ?Film 3? was chosen as the poor solvents, respectively. Based on the above considerations, three fluorescent films were fabricated by adjusting the component and ratio of good solvents and poor solvents. SEM image studies showed that Film 1 is composed of uniform thin film, Film 2 is characterized by short and thick fibers and Film 3 adopts wrinkle-shaped structures. Sensing behavior studies demonstrated that Film 1 is supersensitive to the presence of MAPA and MPEA vapor ?Detection Limit:5.5 ppb for MPEA, a lowest value reported in the literatures? and other two films are inferior to Film 1. This result proved that sensing performance is strongly dependent on the film structure. Interference experiments revealed that some potential interferences like amines, organic solvents, water and fruit residues have little influence on the sensing process. Furthermore, Film 1 shows good photochemical stability and the sensing process is highly selective and fully reversible. Based on the excellent sensing properties, a conceptual MAPA detector which realizes reversible response to MAPA vapor was developed and this lays solid foundation for its real-life applications.In chapter three, another PBI derivative ?PDA? with both 2-ethylhexylamine and long alkyl chains was designed and synthesized. And it was also characterized by 1H NMR and MS. In the design,2-ethylhexylamine with forked structure was specially chosen to prevent ?-? stacking among PBIs and long alkyl chain was selected to enhance the solubility of PBI. It is found that PDA possesses abundant photophysical properties and tends to form H-type aggregates in high concentration. Solvent effect study revealed that PDA has improved solubility in organic solvents such as toluene, chloroform and methylcyclohexane ?MCH? and etc., which is beneficial for assembly behavior. The sensing film was obtained by spin coating PDA solution in MCH. Upon continuous illumination about 2.83 h, the fluorescence intensity decreased only about 6%, indicating that the film is photochemically stable. As is expected, preliminary experiments demonstrated that the film fabricated from MCH solution is also responsive to MPEA. However, the film morphology and sensing performance need to be optimized and improved. Further studies are in progress. |
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