Studies on the Photophysical Properties of Aromatics and Dyes in Isotropic Solvent and in Confined Spaces

The key essence of my thesis work was to explore the use of molecular container cavitands as reaction cavity for manipulating photochemical and photophysical properties of organic molecules. The photochemical and physical properties of organic molecule get easily influenced by several environmental factors making it difficult for detailed studies and further applications. In this regard, cavitands not only provide stable enclosure to a molecule of interest which paves way for detailed systematic studies but also extends the lifetime of reactive intermediates and reduces the relaxation process that usually occurs in solvent phase. We exploited molecular containers such as octa acid, cyclodextrin, and cucurbituril as hosts for various guest molecules, example includes anthracene, tetracene, chrysene, 1,2-benzpyrene, 3,4-benzanthracene and pyrene for their photochemical and photophysical behavior investigation. Complexation of organic molecules with octa acid (OA) was confirmed using 1H NMR and fluorescence techniques. We further studied the electron transfer from donor aromatic molecule inside OA cavity to the coulombically linked viologens confirming the remarkable property of OA allowing molecular communication across its wall. And also, efforts were made to enhance the encapsulated pyrene molecules room temperature phosphorescence with Rb+, Cs+ and Tl+ using heavy atom effect. In order to bring photoactive organic chromophores and metal nanoparticles closer without any covalent bonds, cyclodextrin and cucurbituril functionalized AuNP were prepared and its host-guest complex formation with dye molecule were explored and studied. There has always been significant interest in the development of fluorescent sensors for the physiologically relevant chloride ion, in the published paper, we discuss new squaramide-based chloride sensor whose emission intensity efficiently increased by 40% upon chloride binding