http://localhost:8080/xmlui/handle/123456789/2910 2026-05-09T08:08:28Z 2026-05-09T08:08:28Z Kasana, Preeti http://localhost:8080/xmlui/handle/123456789/6066 2026-04-20T06:03:21Z 2025-12-01T00:00:00Z

Spectroscopic investigattions within ionic liquid based media Kasana, Preeti Most of chemical reactions require a suitable solvent media such as Volatile Organic Compounds (VOCs) or water. The volatile organic solvents contribute a lot to the environmental pollution due to their volatile nature. Furthermore, some of the solutes are not soluble in water due to their poor solubility hence, new and alternative solvent media are required so as to address environmental pollution and ensure sustainability. Ionic liquids offers unique features including non-flammability, thermal stability (high), melting point (low), ionic conductivity (good), interesting solvation properties and their potential environmentally-benign nature. To ascertain the characteristics of these new, alternative solvent media, we are using certain probe molecules possessing significant absorbance and luminescence properties. The photo-physical characteristics of such probes may be impacted by the surrounding solvent environment and hence one can study the properties of the surrounding solvent media by using such probes. This thesis thoroughly tests the concept that ILs and aqueous IL systems may result in altered, preferred dye aggregation and prototropism when compared with conventional organic solvents. The aggregates of cyanine dyes plays important role in various applications including future light harvesting systems, sensors, photoconductors, photography, biology, medicine, nanotechnology. Furthermore, the significance of prototropism and Excited State Proton Transfer (ESPT) reactions can be manifested in numerous applications. The thesis entitled “Spectroscopic Investigation within Ionic Liquid Based Media” deals with study of prototropic behaviour of some of the important prototropic probes such as p-nitrophenol, carbazole and aggregation behaviour of technologically important cyanine dye 1,1’-diethyl-4,4’-carbocynine iodide (DECI), often referred to as kryptocyanine within neat Ionic Liquids (ILs) and IL added aqueous solutions to better understand the unique role of these new and alternative solvent media. The present study was carried out with the aim to control prototropic behaviour of various prototropic probes and aggregation behaviour of cyanine dyes in a desired manner with the help of ILs). The long-term objective of the research is to promote the use of ILs to control dye aggregation and prototropism. In the present work, the proton-transfer reaction of p-Nitrophenol (PNP) was investigated and interestingly, addition of small amount of IL, 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] or 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6] into PNP dissolved in high pH water causes protonation of already present p-Nitrophenolate anion. Protonation of p-Nitrophenolate is attributed to the presence of acidic C2-H protons in [bmim]+ cations associated with both ILs. Furthermore, the extent of protonation induced by addition of [BF4] − based IL is found to be much pronounced as compared to [PF6] − based IL having same cation due iv to difference in hydrolytic properties of [BF4] − based ILs when compared with [PF6] − based ILs. These findings could contribute to technological applications for detection, removal and sensing of environmentally hazardous p-Nitrophenol and its ionic forms from water. Similarly we have reported the unusual excited-state prototropism of an important photoacid carbazole dissolved in water in presence of small amount of added ILs. We have shown that a little amount of additional ILs can have an impact on the excited state prototropic equilibria of carbazole dissolved in water. More specifically, the acidity of added ILs may be used to control excited-state prototropism of carbazole. More interestingly, we discovered that even in the presence of very small amount of any of added ILs, like 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-1-methylpyrrolidinium bis(trifluromethansulphonyl)imide ([bmpyrr][Tf2N]), & 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim][PF6]), the fluorescence emission from the neutral prototropic form of carbazole can be observed even in the presence of very basic conditions (aqueous NaOH, pH 12.6) due to the excited state protonation of the carbazole anion by the proton from the IL cation. The aggregation behaviour of kryptocyanine dye was found to depend upon the identity of Ionic Liquid (IL) present in the aqueous solutions of dye. The presence of small amount of [BF4] −, [PF6] − and [OTf]− anions containing the ILs induced the process of J-aggregation instantly and added ILs acts as promoters for J-aggregation followed by time dependent precipitation. In contrast to [BF4] −, [PF6] − and [OTf]− anions containing ILs, the presence of small amount of Tf2N − anion containing ILs induced the process of J- and H-aggregation simultaneously followed by the time dependent conversion of H-aggregates to J-aggregates. These findings could contribute to improve and broaden the applications of these new and alternative noble solvent media for academia and industry. Kumar, Vinod

2025-12-01T00:00:00Z Rimi http://localhost:8080/xmlui/handle/123456789/5010 2026-04-13T08:49:05Z 2024-10-01T00:00:00Z

Synthesis and applications of hypervalent iodine compounds and metal organic frameworks Rimi Hypervalent iodine reagents have remarkable history as valuable reagents for newlineinnumerable oxidative transformations since the synthesis of first hypervalent iodine newlinecompound; (dichloroiodo)benzene. These reagents served as flipside of toxic heavy newlinemetal oxidants due to their ease of availability, less-toxicity and selectivity. On the newlineother hand, metal-organic frameworks have been found as efficient catalysts in various newlinefields such as sensing, biomedicine, catalysis, adsorption and electrochemical newlineapplications. In this thesis, we delved into synthetic applications of hypervalent iodine newlinereagents and metal-organic frameworks (MOFs). In context to hypervalent iodine newlinereagents, the thesis presents the design and synthesis of some new iodoarenes, newlinefollowed by investigating their catalytic activity towards diverse oxidative newlinetransformations. Besides, some biologically active pyrazole-tethered isoxazoles have newlinebeen synthesized by utilizing diacetoxyiodobenzene in presence of trifluoroacetic acid. newlineAdditionally, the thesis explores the catalytic efficiency of diiodo-precatalysts newlineembedded within MOFs, which exhibit remarkable recyclability in the oxidation of newlinehydroquinone across three cycles. The research also ventures into the field of newlineiodonium salts, detailing the design of new salts and the attempts for their synthesis. newlineOn the MOF front, the synthesis of new cauliflower-like palladium-doped MOF newlinematerials is presented. These palladium-doped MOF material demonstrates its utility newlinein the degradation of dyes and the reduction of nitroaromatic compounds. Notably, the newlinepalladium-loaded MOF material exhibit excellent recyclability in the degradation of newlineCongo red dye and the reduction of 4-nitrophenol. newlineThe findings of this thesis underscore the versatility of hypervalent iodine reagents and newlineMOFs, paving the way for their increased adoption in various fields of chemistry and newlinematerial science. newline Kumar, Ravi and Uttam, Bhawna

2024-10-01T00:00:00Z Himanshi http://localhost:8080/xmlui/handle/123456789/5009 2026-04-13T08:51:28Z 2024-10-01T00:00:00Z

Study of nano material based corrosion inhibitor for metal surface Himanshi The work focuses on synthesizing metal/metal oxide/other nanomaterials and evaluating their corrosion inhibition efficiency on mild steel using weight loss studies, EIS (LPR, PDP, AC impedance), and theoretical analyses. TiOand#8322; NPs, TiOand#8322;/PVP NC, CeOand#8322; NPs, CH-CeOand#8322; NC, PD/CeOand#8322; NC, ZnO NPs, ZnO/PAA NC, and MnO NPs were synthesized via chemical methods such as co-precipitation, sol-gel, and in-situ addition, and characterized using UV-Vis, FT-IR, XRD, SEM/EDAX. Their anti-corrosive performance was tested across 100 500 ppm concentrations and 308 338 K for 3 4 hours. Inhibition efficiency increased with concentration and decreased with temperature, while corrosion rate showed the opposite trend. Thermodynamic and kinetic parameters indicated an endothermic corrosion process (positive and#916;H) and positive and#916;Gads, implying instability of the activation complex. Adsorption followed the Langmuir isotherm, showing mainly chemisorption with some physisorption. EIS results showed increased Rct and decreased Cdl with higher inhibitor concentration, confirming reduced charge transfer and greater surface coverage. Potentiodynamic polarization revealed mixed-type inhibition. Surface analysis (AFM, optical microscopy) showed reduced steel degradation, especially with nanocomposites; doped MnO NPs further lowered surface roughness due to synergistic effects. Theoretical studies (EHOMO, ELUMO, and#956;, and#967;, I, A, and#948;N) supported strong chemical adsorption through electron donation from inhibitors to vacant d-orbitals of mild steel. newline Kumar, Ravi and Uttam, Bhawna

2024-10-01T00:00:00Z Narang, Rajni http://localhost:8080/xmlui/handle/123456789/2913 2025-05-28T09:52:53Z 2024-04-01T00:00:00Z

Study of highly efficient corrosion inhibitors for metals Narang, Rajni Mangla, Bindu

2024-04-01T00:00:00Z