Synthesis, Photo-Physical Properties, and Applications of Nitrogen-doped Carbon Dot

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The thesis addressed various strategies to regulate the photo-physical property and applicability of carbon dots (CDs) by heteroatom (especially Nitrogen(N)) incorporation approach. This thesis pursues a detailed analysis of the structural and optical properties of newly developed N-doped CDs (NCDs). Till now, the source of emission property of CDs is not explained properly, which is the main inspiration of the thesis to explore each detailed photo-physical characteristic of synthesized NCDs and executed the same in the sensing and biological platform. The systematic development of carbon-based quantum dots (carbon and graphene quantum dots) as potential luminescent materials is discussed along with their synthesis procedures, photoluminescent properties, and vast application. The specific detection of Pb2+ and ClO¯ by using surface-functionalized graphene quantum dot (F-GQD) is successfully achieved. The surface modification of graphene quantum dot (GQD) was done by a simple coupling reaction between 2,6-diaminopyridine moiety, and GQD which is further applied to imaging and recognition of ClO¯ in living cells and Pb2+detection occurred by aggregation induced emission enhancement manner whereas the ClO¯ detection consists of energy migration through H-bonding network between amino group of F-GQD and ClO¯. Again, the hydrothermal synthesis was considered for synthesis of highly blue emissive NCDs (quantum yield 22.7 % in an aqueous medium) from 3,6-diaminoacridine hydrochloride and L-aspartic acid for the detection of two analytes i.e., vitamin-B12 and bilirubin. Here also, the mechanism of detection of two analytes are totally opposite in nature. For vitamin-B12, inner filter effect plays the key role for emission suppression, whereas, H-bonding induced energy transfer was operated for detection of bilirubin. Moreover, the NCD was further applied in living cell imaging and successfully recognize vitamin-B12 in HeLa cells. We cover a brief detection strategy to recognize 4-nitroaniline (4-NA) by two different emissive NCD-1 (blue) and NCD-2 (green). Here, the sensing mechanism highly depends on the emission wavelength and solvent system. Moreover, a novel NCD was reported which contains unique optical properties i.e., three different color emissions (blue, green, and red) under different excitation windows and their application of Fe3+ and ascorbic acid detection as well as logic gate preparation. Once more, we synthesized a dual-emissive N-doped carbon dot (NCD) for very specific ratiometric detection of pH and Fe3+ with a distinct ratiometric property. Furthermore, this NCD act as pretty good anti-cancerous agent, and it was recognized intracellular pH as well as exogenous Fe3+ in the breast cancer cell line (MCF-7). A solution-phase white light also constructed by considering the emission property of NCD. In the last, we encompass the whole summary of the existing thesis and future scenarios of this thesis
Supervisor: Sahu, Kalyanasis
Carbon Dot, Fluorescence, Sensing, Biological Applications