| In recent years,benefiting from the rapid development of the industries ofintemet of things,smart materials,wearable devicesand intelligent life,sensing technologies and relevantequipment have made great progress.As an important type of sensing technology,fluorescent sensors have become an important research field and attracted great attention because of their simplicity,designable ability of fluorophores,high selectivity and sensitivity in fluorescent assays.They have been widely used in many fields,such as life science,clinical medicine,food safety,drug analysis,environmental science,industrial fields,hazardous chemicalsdetecting,etc.Despite the progress made in this field,several problems and challenges still exist.During the last two decades,our group committed to the reach on film-based fluorescent sensing,including design of sensing units,fabrication of film devices and construction of relevant sens:ing platforms.Based on the fundamental research,a series of high-performance explosive detectors(SRED)have been developed and appliedin the fields of national defense,military and public security.Therefore,based on the research of our group,developing novel fluorescent molecules,discoveringnew sensing modes,solvingthe key problems in existing research andachieving the more challenging analytes detecting will be throughout the research of this dissertation.On the whole,several nonplanar o-carborane derivatives were designed and synthesized,which exhibited highly fluorescence quantum yields in solid state and photochemical stability.Moreover,due to the porous structures at the molecular level of the films,the analyte molecules could diffuse within the layer with no difficult,that is a necessary for satisfying reversible and fast sensing.Fluorescent sensing studies revealed that the film-based sensors exhibited unprecedented detection and discrimination ability for explosives,illicit drugs,nicotine and volatile organic compounds in vapor phase.Meanwhile,the conceptual detectors based on the sensing filmswere constructed and successfully used for simulated field tests.The thesis is mainly composed of the following four parts:In the first part,we developed a geometrical PBI dimer(PBI-CB),and it shows strong fluorescence and high photochemical stabilityin solid state.Moreover,PBI-CB shows better solubility in common organic solvents and exhibits rich self-assembly property,forming nano-fibers in suitable organic medium.Combination of the PBI-CB fibers with different substrates,three fluorescent films were fabricated,and show unprecedented sensitivity,selectivity and response speed to the existence of six widely abusedillicit drugs,including methamphetamine(MAPA),ecstasy,magu,caffeine,phenobarbital(PB),and ketamine in vapor phase.Importantly,presence of cormnonly found interferences,including odorous substances(toiletries,fruits,dirty clothes,etc.),water,and amido-bond containing organic compounds(typical organic amines,illicit drugs,and different amino-acids)shows little effect upon the sensing.More importantly,discrimination and identification of the drugs can be realized by using the sensors in an array way.Based upon the discoveries,a conceptual,two-sensor based fluorescent detector is developed,and non-contact detection of the illicit drugs is realized.In the second part,three new pyrene-containing fluorophores were designed and synthesized.The obtained fluorophores were further utilized for the fabrication of fluorescent films and the relevant film devices.Fluorescent sensing studies revealed that the individual film-based sensors showed different responses to the 15 representative controlled chemicals,including explosives,illicit drugs and volatile organic compounds.Integration of the devices resulted in a sensor array,which exhibited unprecedented detection and discrimination ability for the 15 chemicals and 8 potential interferences.Importantly,the sensing was fully reversible,and each sensing was completed within 1 min.More importantly,the sensing was performed via vapor sampling,which provides a foundation for stand-off detection.We believe that the results provide a strategy for designing low power,compact and comprehensive fluorescent chemical detectors with satisfactory sensitivity and discrimination capability.In the third part,we developed fouro-carborane-based fluorophores(F1,F2,F3 and F4)which showedmulticolor,high emission(?F?43%)and photochemical stability in solid state.The fluorophores as obtained were further employed forfabricating relevant fluorescent films,and the film-based devices.Additional studies demonstrated that the film-based devices showeddiscriminative responses to 9 representative chemicals including nicotine.Importantly,the device based on F2 showed unprecedentedsensing capability to nicotinein the gaseous phase(down to 3 ppb).Furthermore,the sensor can be extended to detect nicotine at nano-gram level(?0.1 ng/cm2)in aqueous solution.More importantly,tobacco smoke and electronic cigarette can be sensitively and selectively detected.We believe that Film 2-based device as obtained has the potential to be developed into a portable fluorescence nicotine detector.In the fourth part,we report a push-pull-based microenvironment sensitive system,of which perylene monoimide was adopted as an electron-donating unit.As for the electron withdrawing moiety,we turmed our attention to aglobularsubstituent called o-carborane,the intrinsic electron-deficient property have been used for the promising building block of D-?-A system.In addition,owing to steric-hindrance ofo-carborane unit,H-type aggregation of PMIunits can be screened effectively.Therefore,a perylene monoimide-o-carboborane derivative(Ph-CB-PMI)was designed and synthesized,and its solvatochromism performance was preliminarily investigated.As expected,fluorescence and UV-vis absorption studies revealed that introduction of o-carborane functionality leads better solubility in common organic solvents and exhibits typical monomeric absorptionand various emission property in the solvents of n-hexane,THF,DMF and ethanol. |
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