Malzeme Bilimi ve Makine Mühendisliği Ana Bilim Dalı Tez Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/422

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Browsing Malzeme Bilimi ve Makine Mühendisliği Ana Bilim Dalı Tez Koleksiyonu by Author "Tahaoğlu, Duygu"

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    Modelling and investigation of boron-based nanostructures
    (Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2022) Tahaoğlu, Duygu; AGÜ, Fen Bilimleri Enstitüsü, Malzeme Bilimi ve Makine Mühendisliği Ana Bilim Dalı
    Polyhedral boron clusters and their applications have been subject to research in many fields such as medicine, materials science, catalytic applications, energy studies, etc. These molecules owe their popularity to their exceptional 3D stable structures, as well as their various sought-after properties in many applications. This doctoral thesis was prepared within the focus of a computational investigation of different polyhedral borane and carborane clusters by using DFT methods. The results of our studies were reported in two main chapters (Chapters 3 and 4). In the first part (Chapter 3), theoretical evaluation of relative stabilities and electronic structure for [BnXn] 2− clusters were provided. The structural and electronic characteristics of [BnXn] 2− clusters were examined by comparison with the [B12X12] 2− counterparts with a focus on the substituent effects (X = H, F, Cl, Br, CN, BO, OH, NH2). The effects of the substituents were discussed in relation to their mesomeric (±M) and inductive (±I) effects. The results showed that the icosahedral barrier can be reduced through substitution by destabilizing the [B12X12] 2− cluster with symmetry-reducing ligands or ligands with +M effects rather than stabilizing the larger clusters. In the second part (Chapter 4), the investigation of the photophysical properties of carborane-containing luminescent systems was presented. The o-CB-Anth system is known to exhibit a dual-emission property by radiating in the visible region from two low energy conformations with local excited (LE) and hybridized local and charge transfer (HLCT) characters, however, it shows a very low emission quantum yield in solution state similar to many other CB-luminescent systems. In this section, the excited-state potential energy surface (PES) of o-CB-Anth and o-CB-Pent were investigated in detail and the effect of a low-lying CT on the low quantum yield was discussed.