PhD Theses (Nanotechnology)

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Browsing PhD Theses (Nanotechnology) by Author "Hajra, Archismita"

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    Molecular Nanoscale Assemblies in Zero and Two Dimensions
    (2024) Hajra, Archismita
    The thesis entitled as “Molecular Nanoscale Assemblies in Zero and Two Dimensions” is divided into six chapters. In this thesis, we developed a simple strategy to monitor the emergence of novel properties for molecule-based materials when their growth is confined in one or more dimensions at the nanoscale. In the first chapter a literature study on assemblies of different forms of nanoparticulate systems has been briefly discussed. In the second chapter, the emergence of photoluminescence properties for zinc ascorbate acetate nanoparticles was observed in the nano dimension when zinc acetate dihydrate and L-ascorbic acid were subjected to react in the aqueous medium at an ambient reaction condition.1,2 A gradual enhancement in the photoluminescence intensity with a red shift in the emission wavelength was observed when the complex approached the nano dimension by aggregation from the molecular form. In the third chapter, the metal complex of our choice of interest was a manganese cysteine complex formed in the ambient reaction condition between manganese acetate tetrahydrate, and L-cysteine under alkaline condition. Here, the gradual increase in the size of the nanoscale particles was reflected in the magnetic properties. Superparamagnetic, to ferromagnetic to paramagnetic transitions for the manganese cysteine complex nanoparticles were observed as the sizes of the particles increased gradually.3 In chapter four, we investigated the development of moiré patterns in the 2D crystals made of manganese cysteine nanoparticles, and zinc ions as a consequence of relative twists between the consecutive 2D films. Further, the aspect of moiré features on the local electronic environment of the paramagnetic manganese ions was also probed by ESR spectroscopy, where the hyperfine splitting of manganese ions was found to be split further as a consequence of the interfacial moiré field. The appearance of non-central electronic transition peaks was also observed due to the prevalent interfacial moiré field acting at the interface of the 2D crystals.4,5 In chapter five, we have presented a unique way to utilize soft bonds to localize metal ions as lattice points to give rise to precise translational moiré 2D crystals of the zinc phthalate complexes, instead of pure crystals. By utilizing the labile nature of the soft bonds, switching between moiré 2D crystals, and 2D crystals without moiré patterns could be attained reversibly as well.6,7 In the sixth chapter, we have discussed the future prospects of the current works with a brief concluding remark.