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Item EFFECTIVELY CONTROLLING NIR EMISSIVE PROPERTY AND THE ESIPT BEHAVIOR OF MODIFIED STYRYL DYES BY ATOMIC SUBSTITUENT: DFT/TD-DFT APPROACH(Springer Nature., 2025) Shilpa Taneja; Selva Kumar Ramasamy; Bhawna Pareek; Geetha Venkatesan; Govindasami Periyasami; Dineshkumar Sengottuvelu; Department of Chemistry; Geetha VenkatesanRecent literature on biosensing and bioimaging has explored excited state intramolecular proton transfer (ESIPT) cyanide dyes. These classes of fluorescence dyes generally use the classical pyridinium or indolium cations acceptor units' styrene with the ESIPT core. This work studied the photophysical and ESIPT kinetics of novel flavylium cation as an acceptor unit styrene with an ESIPT core using DFT/TD-DFT calculations. Two new ESIPT cyanine dyes, namely (E)-4-(3-(benzo[d]thiazol-2-yl)-2-hydroxystyryl)-7-(dimethylamino)-2-phenyl chromenylium (PSS) and (E)-4-(3-(benzo[d]oxazol-2-yl)-2-hydroxystyryl)-7-(dimethylamino)-2-phenylchromenylium (PSO) were designed and fully studies. This is concerned with studying changes in intramolecular hydrogen bonds, molecular orbitals at the frontier of the ESIPT process, absorption and fluorescence spectra, and excited state energy barriers. As a result, both the systems considered here can undergo an ultrafast ESIPT reaction with PSS and then PSO. Furthermore, ESIPT is more accessible in the normal enol-form first excited singlet (S1) state, with shorter hydrogen bonds. The intersystem crossing between the S1 state and the triplet (T1) state greatly influences the fluorescence efficiency of PSO and PSS. The potential energy curve and transition state energy profiles of PSS and PSO show that ultrafast ESIPT occurs in the state. Furthermore, the PSS shows less energy barriers, which leads to faster proton transfer than PSO. The current study will advance knowledge of the mechanism behind the ESIPT process and help enhance the qualities of the cyanine dye used in ESIPT.Item SYNTHESIS, CRYSTAL STRUCTURE, HIRSHFELD SURFACE, COMPUTATIONAL AND BIOLOGICAL STUDIES OF SPIRO-OXINDOLE DERIVATIVES AS MDM2-P53 INHIBITORS(Springer Link, 2024-08) Monisha, Sivanandhan; Sutha, Ragupathy; Arumugam, Thangamani; Amutha, Parasuraman; Department of Chemistry; Amutha, ParasuramanThe spiro-oxindole derivatives were synthesized via a 1,3-dipolar cycloaddition approach and characterized by FT-IR, 1H, 13C NMR and mass spectral techniques. The single crystal XRD of 6d further validates the formation of compounds. DFT calculations indicated the reactive nature of compound 6d. Docking studies with 5LAW disclosed the minimum binding energy of - 10.83 kcal/mol for 6d. Furthermore, safe oral bioavailability was ensured by the physicochemical, pharmacokinetic, and toxicity predictions. The anticancer analysis of synthesized compounds showed substantial activity against A549 cells, notably with an IC50 value of 8.13 ± 0.66 µM for 6d compared to standard doxorubicin. 6d was also evaluated for cytotoxicity against L929 healthy cells and A549, showing selectivity towards A549 than healthy cells. AO/EB staining method showed early apoptotic cellular death in the A549 cell line in a dose-dependent manner.Item ENHANCED HYDROGEN STORAGE OF ALKALINE EARTH METAL-DECORATED BN (N = 3-14) NANOCLUSTERS: A DFT STUDY(Springer Link, 2024-01) Parimala Devi, Duraisamy; Prince Makarios Paul, S; Praveena, Gopalan; Abiram, Angamuthu; Department of Physics; Praveena, GopalanBoron-based nanostructures hold significant promise for revolutionizing hydrogen storage technologies due to their exceptional properties and potential in efficiently accommodating and interacting with hydrogen molecules. In this paper, boron-based Bn (n = 3-14) nanoclusters decorated with alkaline earth metals (AEM = Ca and Be) were investigated for hydrogen storage applications based on density function theory (DFT) calculations. To evaluate H2 adsorption capability, the adsorption energies, frontier molecular orbitals (FMOs), natural bond orbital (NBO), and quantum theory of atoms in molecule (QTAIM) analysis are performed. The primary aim of this research work is to achieve targeted value of 5.5 wt% set by the US Department of Energy (DOE) for the year 2025. The results revealed that B5Ca2, B6Ca2, and B10Ca2 structures have the ability to hold up to 12H2 molecules with gravimetric capacities of 15.20, 14.21, and 8.60 wt%, respectively, when compared to other boron structures decorated with calcium. Similarly, for Be-decorated structure, B3Be2 structure can accommodate 3H2 molecules with gravimetric capacity of 10.59 wt%. The result of this study indicates that AEM-decorated Bn nanoclusters hold great promise as potential materials for hydrogen storage.