| The interest in fluorescent sensing in the development of sensor technology and related equipment has dramatically risen in recent years since it shows tremendous advantages in terms of excellent designability,high sensitivity and easily array-fabrication.Consequently,the technology of fluorescent sensing provides ever immense performances in their myriad applications including detection of toxic chemicals,environmental science,food safety,bioscience,etc.As an exceptional technology of fluorescent sensing,film-based fluorescent sensing with an outstanding favoring miniaturized and device-oriented,and will be an important development direction in the field of the future fluorescent sensors.During the past two decades,numerous efforts have been devoted by our lab to exploit new and efficient film-based fluorescent sensing materials for instrumentations,and a series of high-performance detectors have been developed and applied in the military and public security.As an important part of fluorescent sensing,the choice of fluorescent compound is the key.Perylene bisimide derivatives have the advantages such as high molar extinction coefficient and fluorescence quantum yield,and show attractive application prospects in the fluorescent sensors.Therefore,based on the research of our group,several PBIs that modified at bay positions were used in this dissertation,and various functional groups were introduced to enhance the solubility.First,the photophysical behaviors were systematic and in-depth investigated to developing novel strategies for fluorescent molecules design.Then,the assembly behaviors were explored based on the molecular characters and fabricated the fluorescent film with different methods.At last,we chose the biomarkers and diamines as analytes,which are highly challenging in human health and life security.Fluorescent sensing studies show that the film-based films exhibited reversible and fast sensing toward volatile organic compounds that tested in vapor phase.Meanwhile,the conceptual detectors based on the sensing films were constructed and successfully used for simulated simples test.In detail,the dissertation is mainly composed of the following four parts:In the first part,we have elucidated the origin of the positive temperature effect in fluorescence emission of a newly designed perylene bisimide(PBI)derivative with two naphthyl units containing or tho-methoxy group(NM)at its bay positions(PBI-2NM).A key point in the elucidation is the finding of a weak hydrogen bond(<5.0 kcal/mol)between the methoxy group of the NM unit and a nearby hydrogen atom of the PBI core.It is the bonding that drives co-planarization of the different aromatic units,resulting in delocalization of the ?-electrons of the compound as synthesized,inducing fluorescence quenching via intramolecular charge transfer(ICT).With raising temperature,the co-planar structure could be distorted,in part,resulting in decreased degree of ICT,and hence leading to enhanced fluorescence emission.The unique positive temperature effect in emission induced by H-bond driven co-planarization may pave a new avenue in designing functional molecular systems complementary to conventional methodologies.In the second part,cholesterol(Chol)was modified two bay positions of perylene bisimide,resulting in a derivative of PEBC with improved solubility in organic solvents and enhanced self-assembly properties.Accordingly,a fluorescent film with optimized fibrillar networked structures was fabricated by adjusting the assembly behavior of PEBC in mixed solvents.Sensing performance studies demonstrated that the as prepared film is super-sensitive and selective to the presence of aniline and o-toluidine in air.Based on the studies,an aniline,an important biomarker of lung cancer,sensor was constructed.Sensor's performance studies demonstrated that aniline could be sensitively,selectively,reversibly and fast detected.The response time is less than 1 s,the calculated detection limit(DL)is?15 ppb,and presence of common organic amines and solvents show little effect upon the detection.Moreover,the sensor works well when simulated exhale from lung cancer patients is employed as a sample,indicating its great potential in the diagnosis of lung cancer.In the third part,two hydrophilic residues were modified with at bay positions of PBI,resulting in an amphiphilic derivative,PEBBO and two control compounds.Photophysical studies revealed that the compounds show good solubility in common organic solvents.Accordingly,a fluorescent film was constructed via utilization of the well-known Langmuir-Blodgett technique.Sensing performance studies revealed that the film as prepared is sensitive and selective to the presence of diamines in air.Specifically,(1)the experimental detection limit is lower than 0.016 g/m3 and the linear range of the analysis extends from 0.33 g/m3 to 8.20 g/m3 when ethylenediamine was adopted as an example analyte;(2)presence of other amines and solvents shows little effect upon the detection;(3)the response time is less than 5 s.Considering the importance of diamine sensing,the convenience of fluorescence techniques and the superiorities of the film and method as developed,it is believed that the present work is of great importance for promoting technical progress in diamine sensing and of pivotal importance for air and food quality monitoring.In the fourth part,three new PBIs that derived at bay positions were designed and synthesized.The obtained compounds were used for fabrication of the fluorescent films and show high photochemical stability.Then,a conceptual sensor array was constructed based on this.Fluorescent sensing studies revealed that the sensor array showed discriminative analysis of heptane,acetone and aniline,which are three kinds of biomarkers of lung cancer exhale breath,and the sensing was fully reversible with response time within 1 s.Moreover,the exhale breath of healthy people was also detected under the process of preconcentration.Considering the complexity of exhale breath,using of array is the necessary in the future detection. |
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