Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Macrocycles-assisted polymeric self-assemblies fabricated by host-guest complexation and their applications(Royal Society of Chemistry, 2020) Velmurugan, K.; Mohan, M.; Li, B.; Wang, K.; Zuo, M.; Hu, X.-Y.Macrocycles exhibit unique features with prospective applications due to their inherent structural features combined with rigidity and functionality. Developing macrocycles-assisted polymeric self-assemblies (MPs) is one of the promising ways to convert macrocyclic polymers into functional materials with responsiveness, endowing them with realistic features such as self-healing, good processability, and recyclability. The present review focuses on the rational design of MPs, over the past decade, with realistic potential applications. The constructions of MPs mainly focuses on the following facets: (i) those assembled from macrocyclic side-chain polymeric hosts interacting with small molecular/polymeric organic and inorganic guests, and (ii) those assembled from macrocyclic monomers interacting with side-chain polymeric guests. These resultant MPs include the dynamic cross-linking of different copolymeric hosts and/or guests, which further leads to the formation of supramolecular self-assembled nanomaterials with unique functionalities. We also discuss the fabrication of stimuli-responsive MPs that are influenced by various external stimuli, and the resultant supramolecular host-guest complexation-mediated reversible self-assemblies are also highlighted. Furthermore, a wide range of applications of MPs, including self-healing materials, adhesives, adsorbents, drug delivery, and smart windows, and their modes of assemblies are elaborately presented. As far as we know, this is the first review particularly focusing on the side-chain polymeric host-guest interactions and their self-assemblies for diverse applications, whereas linear polymers and post-polymerizations are not included. This review summarizes the fundamental design concepts in the fabrication of polymeric backbone-assisted MPs, which provides new directions for future research in the field of supramolecular chemistry and materials chemistry. © 2020 The Royal Society of Chemistry.Item Synthesis and spectral investigation of colorimetric receptors for the dual detection of copper and acetate ions: application in molecular logic gates(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2017) Pangannaya, S.; Kaur, A.; Mohan, M.; Raval, K.; Chand, D.K.; Trivedi, D.R.Colorimetric receptors L1, L2 and L3 possessing –OH functionality as binding site and –NO2 as signalling unit with varied positional substitution of –OMe functionality has been designed and synthesised by simple Schiff base condensation reaction. Receptors L1, L2 and L3 showed selective response towards AcO?ion among other interfering monovalent anions viz., F?, Cl?, Br?, I?, NO3 ?, HSO? 4 and H2PO? 4. L2 imparts high selectivity towards AcO? ion assisted by push-pull effect of –NO2 and –OMe functionality in conjugation with imine linkage. The binding constant for L2–OAc complex was found to be 9.04 × 104 M?2. L2 exhibited a detection limit of 0.61 ppm towards NaOAc. The selectivity of L1 towards Cu2+ ions with a lower detection limit of 1.81 ppm implies the role of electron donating –OMe in favouring the coordinative interaction of hetero atoms of L1 with Cu2+ ions. The selective detection of AcO? and Cu2+ ions is further established with OR and INHIBIT logic gate application of receptors L1, L2 and L3 correspondingly. The colorimetric studies reveal the role of OMe functionality in the selective detection of AcO? and Cu 2+ ions in aqueous media. © 2017 Informa UK Limited, trading as Taylor & Francis Group.Item Colorimetric and fluorometric turn-on sensor for selective detection of fluoride ions: Sol-gel transition studies and theoretical insights(Royal Society of Chemistry, 2018) Pangannaya, S.; Mohan, M.; Trivedi, D.R.A new organic receptor R1 based on a naphthyl unit covalently linked to a long alkyl chain has been designed, synthesized and characterized by standard spectroscopic techniques. The colorimetric response of receptor R1 from colorless to a pale yellow color and blue fluorescence emission in the presence of F- ions revealed its selective sensing ability in the solution phase. UV-Vis titration, fluorescence titration and 1H NMR titration studies confirmed the formation of the R1-F- complex. Receptor R1 formed a stable gel in DMSO and was confirmed through the standard heating-and-cooling method. Addition of F- ions resulted in disruption of the gel forming a solution that exhibited blue fluorescence emission. The binding constant of the R1-F- complex was found to be of the order of 5.9 × 105 M-1. DFT studies revealed the formation of the receptor-anion complex agreeing well with the experimental results. The detection limit was calculated and found to be 0.8 ppm, implying the potential for application of receptor R1 in environmental applications. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Photophysical and electrochemical properties of organic molecules: Solvatochromic effect and DFT studies(Elsevier B.V., 2018) Mohan, M.; Pangannaya, S.; Satyanarayan, M.N.; Trivedi, D.R.A series of five Schiff base molecules M1, M2, M3, M4 and M5 have been designed and synthesized by aldol condensation reaction. Synthesized molecules have been characterized by standard spectroscopic techniques in order to confirm their structural traits. The solvatochromic behavior of molecules M1 to M5 in solvents of varying polarity were investigated by UV–Vis, fluorescence spectroscopy and supported by TD-DFT calculations. DFT studies performed in the gas phase confirmed the energy stabilized structure of the molecules M1 to M5. Structural characteristics of molecule M2 favored higher fluorescence emission with a quantum yield of 0.35 and a solid-state emission of 512 nm. Fluorescence lifetime measurement of the molecules M1 to M5 exhibited a lifetime of order 2–5 ns. Overall, molecule M2 can find its application in organic light emitting diodes as a non-dopant emitter material. © 2018 Elsevier B.V.Item Hydrazinylpyridine based highly selective optical sensor for aqueous source of carbonate ions: Electrochemical and DFT studies(Elsevier B.V., 2018) Thimaradka, V.; Pangannaya, S.; Mohan, M.; Trivedi, D.R.A series of new receptors PDZ1–3 based on 2-(arylidenehydrazinyl)pyridines have been designed and synthesized for the detection of biologically and environmentally important ions. The colorimetric detection of CO32 ? using neutral organic receptor PDZ-1 has been achieved with characteristic visual colour change from yellow to green accompanied by a large redshift of 215 nm in absorption maxima. UV–Vis spectroscopic and cyclic voltammetric studies reveal the stoichiometry of binding and electrochemistry of host-guest complex formation. The binding constant was found to be 0.77 × 104 M? 2. In addition, electrochemical studies provide an insight into the stability of the complex. DFT studies performed on the PDZ-1 and PDZ-1 ? CO32 ? complex reveal the binding mechanism involved in the anion detection process. PDZ-1 is highly selective for carbonate and does not show any colorimetric response towards any other anions or cations, while PDZ-2 and PDZ-3 remain inactive in the ion detection process. The limit of detection (LOD) and limit of quantification (LOQ) of PDZ-1 for carbonate was found to be 0.11 mM and 0.36 mM respectively. Considerable binding constant and limit of detection make PDZ-1 to be used as a real time sensor for the detection of carbonate in environmental and biological samples. © 2017 Elsevier B.V.Item Multicoloured Thiophene Based AIEgens: Single Crystal Structure Elucidation, Spectral Behaviour and DFT Studies(Wiley-Blackwell info@wiley.com, 2018) Mohan, M.; Pangannaya, S.; Satyanarayan, M.N.; Trivedi, D.R.A series of Schiff base thiophene derivatives, D1 to D9, which exhibits a phenomenon of aggregation-induced emission enhancement (AIEE) have been synthesised and characterized by standard spectroscopic techniques. Multicoloured emission enhancement has been achieved just by introduction of electron donating and withdrawing substituent on the thiophene moiety. Few of the molecules in the series exhibited enhanced fluorescence emission intensity in solvent mixture in comparison with that observed in pure solvent supportive of AIE. Single crystal x-ray diffraction (SCXRD) studies on selected molecules, D6 and D7 of the series revealed the existence of planar structure and a herringbone type of crystal packing arrangement. In specific, molecules D6 and D7, possesses a larger ?-? stacking distance of around 4.866 Å and 4.636 Å, which curbs all the non-radiative pathways, in turn leading to AIEE. DFT and TDDFT calculations confirm the structural planarity supportive of SCXRD analysis and the nature of electronic transition correlating well with the experimental results. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimItem Photophysics of proton transfer in hydrazides: A combined theoretical and experimental analysis towards OLED device application(Royal Society of Chemistry, 2019) Mohan, M.; Satyanarayan, M.N.; Trivedi, D.R.Hydrazides generate phototautomers and thus, a mechanistic interpretation to uncover the excited state dynamics of such systems is highly necessary to theorize principles based on experimental speculations. Accordingly, focus on the proton transfer barrier, which is a questionable step-wise or hypothetical simultaneous double proton transfer on structurally favored species, is quintessential; however, to the best of our knowledge, theoretical insights into such findings remain rare. Thus, TX, PX and FX (where X = 2 and 3) were designed and synthesized by incorporating hydrazides, which exhibit the phenomenon of excited state intramolecular proton transfer (ESIPT). Some of the molecules exhibited electroluminescence when employed as an active emitter material in fabricated OLED devices. Theoretical predictions support the presence of extended conjugation in TX, PX and FX (where X = 2 and 3) to support ESIPT efficiently in comparison with TX, PX and FX (where X = 1). The solvatochromic study revealed that TX, PX and FX (where X = 2 and 3) exhibit a distinct double peak in THF solvent, characteristic of ESIPT. Interestingly, for some of the molecules, emission in thin film form showed a double peak, which indicates ESIPT in the solid state. However, it was found that aggregation induced emission (AIE) was inactive in these molecules. The geometrical attributes of the molecules and the nature of electronic orbital distribution well underline the principle supporting excited state proton translocation. The theoretically estimated energy transitions exhibited good correlation with the experimental results. Also, the potential energy scans revealed the molecules possess a lower forward barrier at their excited state in comparison with that of their ground state, promoting ESIPT. The potential energy surface scans performed on structurally favored species confirmed the impossible double proton transfer and highly difficult step-wise double proton transfer. © 2019 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Analysis of traffic growth on a rural highway: A case study from India(Institute for Transport Studies in the European Economic Integration istiee@univ.trieste.it, 2019) Nandakumar, R.; Mohan, M.Over the years, the rate of traffic growth had always been a significant concern in the development of road infrastructures as it could either lead to premature failure of the pavement or could result in the wastage of valuable resources. The lack of proper study regarding the prediction of traffic growth has led to development of concerns in this field. The present study attempts to develop traffic forecasting models using the data collected from 2013 to 2017at the Paliyekkara toll plaza situated in southern part of India. The study identified Gross Domestic Product, population and vehicle ownership as the main factors that influence traffic growth and an exponential model was developed relating these factors with traffic volume. The proposed model was then validated by comparing the forecasted traffic with the actual traffic data of 2018. Further, on comparing with the output from existing models, it was concluded that the proposed model outperforms the available models as it had the least error in prediction. The study also modeled the variation in traffic volume that occurs in a year and this could be used to forecast the traffic for any particular month of any year. © 2019 Institute for Transport Studies in the European Economic Integration. All rights reserved.Item Selective colorimetric chemosensor for the detection of Hg2+ and arsenite ions using Isatin based Schiff's bases; DFT Studies and Applications in test strips(Elsevier B.V., 2019) TG, A.K.; Tekuri, V.; Mohan, M.; Trivedi, D.R.Three isatin appended Schiff's base chemosensors (CS1-CS3) were synthesized and characterized by FT-IR, 1H-NMR, 13 C-N MR, and LC–MS. The sensing ability of the synthesized chemosensors towards Hg2+ and AsO2? ions was established through colorimetric / UV–vis techniques and achieved detection limit at ppm levels. All chemosensors CS1-CS3 exhibited rapid colorimetric / UV–vis response with Hg2+, also, CS1 and CS3 displayed dual-ion selectivity towards AsO2? (colour changes orange to aqua-blue) and Hg2+ (from orange to colorless). The binding properties and detection limit has been examined through the UV–vis instrument. The mechanism of binding was investigated using various analytical techniques like FT-IR, UV–vis, mass and 1H-NMR titration experiments. The experimental results were supported by theoretical DFT study. The developed colorimetric chemo-sensors showed a good binding affinity towards metal ions and exhibited good linearity (R2 ? >0.99). Further, the developed sensors were used for test strips application to detect the Hg2+, AsO2? ions and achieved naked-eye detection at ppm levels. Hence, CS1-CS3 sensors find its practical application in efficient detection of toxic metals like Hg2+ and AsO2?. © 2018 Elsevier B.V.Item Functionalized pyrene-based AIEgens: synthesis, photophysical characterization and density functional theory studies(John Wiley and Sons Ltd, 2019) Mohan, M.; James, J.; Satyanarayan, M.N.; Trivedi, D.Three new pyrene-based derivatives P1, P2 and P3 with a substituted pyrazole were designed, synthesized and characterized using standard spectroscopic techniques. Ultraviolet–visible (UV–vis) spectroscopic studies for P1–P3 uncovered a finite bathochromic shift of the molecules in solvents of varying polarity. Photoluminescence (PL) studies revealed the significant fluorescence emission of all molecules in higher polar solvents such as MeOH and dimethylformamide (DMF). Fluorescence quantum yield studies demonstrated the importance of P3 possessing cyanofunctionality for imparting higher emission with a quantum yield of 0.36%. Ratiometric studies performed in a tetrahydrofuran (THF)/H2O mixture indicated fluorescence enhancement with increasing overall percentage of water, confirming the aggregation-induced emission effect. Cyclic voltammetry study of molecules P1–P3 revealed an irreversible oxidation peak and the band gaps were calculated to be 2.26 eV for P1 and 2.31 eV for P2 and P3 respectively. Density functional theory (DFT) studies performed on molecules P1–P3 validate the structure correlation of the molecules. Theoretically estimated highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and bandgap correlated well with the experimental values. Furthermore, time-dependent (TD)DFT showed that the major contribution for the electronic transitions occurring in the system was governed by HOMO-1 and LUMO+1 orbitals. © 2019 John Wiley & Sons, Ltd.
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