Browsing by Author "Abhineet Verma"

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Achieving AIE from ACQ in positional isomeric triarylmethanes
(Royal Society of Chemistry, 2022) Soumya Singh; Abhineet Verma; Satyen Saha
Tuning photophysical properties by a small structural change in triarylmethane (TAM) derivatives has always been a centre of attention because of their distinguished and extensive applications in the dye and medicinal industries and in the development of organic functional materials. Here, we report two new isomeric TAM derivatives, which show drastic differences in fluorescence properties in the solid state. The usual ‘aggregation caused quenching’ (ACQ) is overcome by a change in the substitution position in naphthalene derivatives, leading to the much desired ‘aggregation induced emission’ (AIE). Such drastic dependence of photophysics on positions in TAM derivatives indicates a largely unexplored area of research to obtain solid-state emitting materials based on TAM. © 2022 The Royal Society of Chemistry
Anharmonic phonon interactions and the Kondo effect in a FeSe/Sb2Te3/FeSe heterostructure: a proximity effect between ferromagnetic chalcogenide and di-chalcogenide
(Royal Society of Chemistry, 2022) Labanya Ghosh; Mohd Alam; Mahima Singh; Srishti Dixit; Satya Vijay Kumar; Abhineet Verma; Prashant Shahi; Yoshiya Uwatoko; Satyen Saha; Archana Tiwari; Ajay Tripathi; Sandip Chatterjee
In this report, we have introduced magnetic ordering into the nontrivial system of conventional topological insulators (TIs) by creating magnetic interfaces. In this context, antimony di-chalcogenide Sb2Te3 sandwiched between two thin layers of FeSe was prepared using the pulsed laser deposition (PLD) technique. The prepared heterostructure demonstrated good crystallinity along with homogeneous morphology displaying pyramid-shaped characteristic triangular islands. To comprehend the temperature and magnetic field modulated inter-layer properties of the prepared hetero-structure, transport, magneto-transport and magnetic properties were investigated. These properties establish the signature of the Kondo effect below 15 K, which has been attributed to the antiferromagnetic spin alignment in that temperature range. At around 150 K, longitudinal and transverse resistivity shows the metal-semiconductor transition, which was further elucidated through the anharmonic decay model in vibration phonon modes using Raman spectroscopy. Furthermore, a significant local spin evolution was explored at around 475 K by studying the magnetic properties of the system. The temperature dependency of the Raman modes confirmed the spin-phonon coupling initiated by local charge ordering at the proximity of the interface in the prepared hetero-structure. © 2022 The Royal Society of Chemistry.
Asparagus racemosus root-derived carbon nanodots as a nano-probe for biomedical applications
(Springer, 2022) Gaurav Gopal Naik; Tarun Minocha; Abhineet Verma; Sanjeev Kumar Yadav; Satyen Saha; Ashish Kumar Agrawal; Sanjay Singh; Alakh N. Sahu
Nowadays, green nanotechnology has emerged as a crucial and eco-friendly approach to combat the problems affecting human health or the environment. It deals with the extensive utilization of plants owing to their cocktail of natural and chemical substances to eliminate adverse pollutants involved in the synthesis of nanomaterials. Herein, we report a facile one-step hydrothermal carbonization approach synthesizing fluorescent bluish-green carbon nanodots (CNDs) using Asparagus racemosus roots termed ARCD. The fluorescence quantum yield of ARCD was further improved by surface passivating it with a 1:1 ratio of Carrageenan (CAR) and Polyethylenimine (PEI), termed ARCCD. First, we demonstrate the application of ARCD and ARCCD as a nano-probe for sensing As3+ and Ag+. Second, we show an inhibitory effect on cancer cell proliferation against breast (MDA-MB-231) and cervical (SiHa) cancer. Also, no significant cytotoxicity was observed in the normal kidney (HEK 293) cells, indicating cytotoxic specificity of the developed CNDs. Third, we demonstrate antibacterial activity against clinically isolated multi-drug-resistant strains and free radicals scavenging potential. Next, we present the in vivo toxicity evaluation of these CNDs in Swiss albino mice, which exhibited minimal toxicity as confirmed by biochemical, hematological, and histological parameters. This study deals with an innovative approach to constructing a multifunctional nano-probe for potential biomedical and environmental applications. Graphical abstract: [Figure not available: see fulltext.]. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Biocompatible thermoresponsive N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide-based random copolymer: synthesis and studies of its composition dependent properties and anticancer drug delivery efficiency
(Royal Society of Chemistry, 2022) Sourov Mondal; Archana Kumari; Kheyanath Mitra; Abhineet Verma; Satyen Saha; Biswajit Maiti; Ranjeet Singh; Partha Pratim Manna; Pralay Maiti; Hironobu Watanabe; Masami Kamigaito; Biswajit Ray
A new acrylamide monomer, N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide (M3i), consisting of both isopropyl and isopropylamidopropyl moieties, has been synthesized from isopropylamine and N-isopropylacrylamide via an aza-Michael addition reaction followed by amidation with acryloyl chloride. The homopolymer of M3i (polyM3i) and a series of random copolymers of M3i and poly(ethylene glycol)methyl ether acrylate (PEGA: CH2 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 CHCO2(CH2CH2O)nMe, Mn = 480, n = 9 on average) with varying compositions have been synthesized via reversible addition-fragmentation chain transfer polymerization using 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as well as 1-phenylethyl phenyl dithioacetate (PEPD) as a RAFT agent. These polymers have been characterized by 1H NMR, FTIR, GPC, UV-Vis, fluorescence, TGDTA, DSC, DLS, and TEM techniques. A lower critical solution temperature (LCST) and glass transition temperature (Tg) for polyM3i prepared using DDMAT were observed at 17 and 133 °C, respectively, while for a polymer formed using PEPD, no LCST was observed until 0 °C and its observed Tg was found at 127.3 °C. The polymers are thermally stable up to 300 °C. Upon an increase in the M3i content in the copolymers, LCST decreases, Tg increases, and the apparent hydrodynamic diameter decreases. Moreover, the effects of concentration and the addition of urea and sodium chloride on the LCST of the copolymer with an LCST close to body temperature were studied. Owing to the incorporation of PEGA, a higher critical micellar concentration and larger TEM particle size of this copolymer were observed with respect to those of polyM3i. The usefulness of the micelles of the copolymers as nano-carriers for the drug doxorubicin was explored. The in vitro tumoricidal activity of the micelles of the doxorubicin-loaded copolymers was also assessed against Dalton's lymphoma cells. © 2022 The Royal Society of Chemistry.
Confocal Raman microscopic evidence for cyclic water Pentamer, at high temperatures in a supramolecular host of [Cu(cyclam)(N3)2]·4H2O
(Elsevier B.V., 2022) Abhineet Verma; Nattamai Bhuvanesh; Joseph Reibenspies; Satyen Saha; Sailaja S. Sunkari
Here, we report the existence of a pentameric water cluster in the host framework of [Cu(cyclam)(N3)2]·4H2O, that is stable upto 167 °C, well above the boiling point of water. The pentameric cluster structure embedded in the host framework is evident from the single crystal studies. The high thermal stability is confirmed by TGA and temperature dependent confocal Raman microscopic studies, where loss of water bands is well captured between 167 and 170 °C, besides its existence through SCXRD studies. To the best of our knowledge, this is the first report where temperature dependent confocal Raman microscopic investigation is used to study the stability of water in crystal environment. The study promises that temperature dependent confocal Raman microscopy can be an efficient tool to investigate the existence and stability of small water clusters, precisely in restricted environments. © 2022 Elsevier B.V.
Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications
(Wiley-VCH Verlag, 2019) Sankalan Mondal; Abhineet Verma; Satyen Saha
Triarylmethanes, compounds in which the central carbon atom is attached to three aryl rings, have a wide variety of photophysical properties which are utilized in the dye industry and also in the development of novel fluorescent tags and biomarkers. The aryl rings attached to the central carbon atom of the parent molecule triphenylmethane can freely rotate. Bridging the aryl rings of triarylmethanes with heteroatoms or through bonds decreases the conformational flexibility enjoyed by the parent molecules. Conformationally restricted triarylmethane (CRT) molecules like 9-arylxanthenes (oxygen bridging), 9-arythioxanthenes (sulfur bridging), 9,10-dihydro,9-arylacridines (nitrogen bridging), and 9-arylfluorenes (bridging through C–C bond) have decreased conformational flexibility and display amphihydric behavior which results in benzenoid structure and quinoid structure of these molecules. The quinoid form of these molecules displays very rich photophysical properties which are the subject of this review. These molecules also have widespread utility, and over the last decade, a number of studies have been focused on the synthesis, photophysical properties, and applications of molecules derived from this core structure. Through this review, we intend to give the readers an outlook on the different strategies employed to synthesize these molecules and also provide a broader perspective on the various intriguing properties of these molecules. The applications of these classes of molecules in diverse fields like photocatalysis, chemical biology, pharmaceutical chemistry, and bio-imaging are discussed. Also, the areas that need to be further developed are highlighted, which may provide a further impetus in the development of this class of molecules. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Counterion Influenced Metal-Organic Frameworks of Cyclam with CuII
(John Wiley and Sons Inc, 2023) Abhineet Verma; Nattamai Bhuvanesh; Joseph Reibenspies; Sailaja S. Sunkari
Cyclam is one of the simplest macrocycle that forms stable metal chelates, much explored for their material and biological applications. Varying anion shape is an effective strategy to modulate the supramolecular structure, inspite of same molecular structure. Here, we report six new complexes of cyclam with CuII bound to counterions of different shapes viz., linear (NCS−/N3−), bent (N(CN)2−) or spherical (Cl−/Br−/I−) in which the shape of the anion leads to distinctly different supramolecular structures (ladder/linear chains with linear anions), braid like (with bent anion) and 3-D hydrogen bonded networks (with spherical anions) due to changes in the non-covalent interactions, inspite of the same molecular structure. The variations in packing are responsible for their different thermal properties. With metallo-cyclams being explored for their efficacy in medical and material fields, studies of this type may offer potential candidates to explore. © 2023 Wiley-VCH GmbH.
Defect induced ferromagnetic ordering and room temperature negative magnetoresistance in MoTeP
(NLM (Medline), 2021) Debarati Pal; Shiv Kumar; Prashant Shahi; Sambhab Dan; Abhineet Verma; Vinod K. Gangwar; Mahima Singh; Sujoy Chakravarty; Yoshiya Uwatoko; Satyen Saha; Swapnil Patil; Sandip Chatterjee
The magneto-transport, magnetization and theoretical electronic-structure have been investigated on type-II Weyl semimetallic MoTeP. The ferromagnetic ordering is observed in the studied sample and it has been shown that the observed magnetic ordering is due to the defect states. It has also been demonstrated that the presence of ferromagnetic ordering in effect suppresses the magnetoresistance (MR) significantly. Interestingly, a change-over from positive to negative MR is observed at higher temperature which has been attributed to the dominance of spin scattering suppression.
Designing symmetrically folded scaffolds of pyridazinone and triazinone derivatives linked via N,N-diethyl-4-nitro-benzenesulfonamide to explore luminescent materials
(Royal Society of Chemistry, 2025) Vipin Kumar; Krishanu Bandyopadhyay; Manisha Nidhar; Vishal Prasad Sharma; Priyanka Yadav; Suman Gill; Priyanka K. Sonker; Abhineet Verma; Satyen Saha; Ashish Kumar Tewari
The study investigates π⋯π interaction in an aromatic-heteroaromatic folded scaffold as well as (NO)π⋯π(arene) and O⋯π(arene) of pyridazinone and 1,2,4-triazinone and their implication for the design of luminescent materials. The research is focused on elucidating the materials' emission spectra and specifically emphasizing the donor-accepter stacking phenomena in the synthesized compounds by altering heteroaromatic units. The studies enlightened the effect of the methoxy group on emission spectra obtained by flipping the DPM molecule in the liquid and solid phases. Results highlight the importance of intramolecular and intermolecular interactions in determining the optical and electrical properties of organic materials. The full spectral profile and quantum yield (φ) of all compounds were examined in the liquid state. Crystallographic data for compounds DP, DT, DPM, and DTM are presented, highlighting the distinct conformers and stacking strength and affirming the stability of crystal geometry. Furthermore, theoretical studies established the correlation between molecular structure and the absorption spectra of molecules. © 2025 The Royal Society of Chemistry.
Drastic influence of amide functionality and alkyl chain length dependent physical, thermal and structural properties of new pyridinium-amide cation based biodegradable room temperature ionic liquids
(Elsevier B.V., 2022) Supriy Verma; Abhineet Verma; Madalasa Mondal; Namburi Eswara Prasad; Jyoti Srivastava; Saurabh Singh; Jay Prakash Verma; Satyen Saha
A series of new room-temperature ionic liquids (RTILs) based on biodegradable pyridinium carboxamide cation and conformationally flexible NTf2 anion have been synthesised. The variation of thermo-physical properties of these RTILs with alkyl chain length size has been studied and compared with corresponding parental pyridinium NTf2 ILs. A drastic change in thermophysical properties has been noted on the introduction of the amide functionality on pyridinium cation moiety. The crucial role of amide functionality is also important concerning biodegradability as it acts as an active site for an enzymatic attack, helpful toward biodegradation. Besides, the dependence of thermal and physical properties on alkyl chain length is also noteworthy. A detailed DFT based theoretical studies substantiate the experimental observation of chain length dependence melting point variation and successfully correlated that with stabilisation energy. Conformational dynamics of NTf2 anion (between transoid and cisoid) has been elucidated by Raman spectroscopic studies. Interestingly, the data demonstrate that the conformation of NTf2 anion depends on the chain length of the cation, clearly indicating anionic interaction with the hydrophobic region of the cation. This information is crutial as it vindicates the fact that multiple weak interaction do exist in ILs making it a complex nonostructured system composed of ions. © 2021 Elsevier B.V.
Dual-Antenna Trimetallic Lanthanide Complexes for Enhanced Near-Infrared Luminescence
(John Wiley and Sons Ltd, 2025) Krishanu Bandyopadhyay; Abhineet Verma; Satyen Saha
Lanthanide [Ln(III)] ions are known for their unique near-infrared (NIR) luminescence, typically achieved through indirect excitation via the antenna effect. Organic ligands, such as N,N-bis(3-methoxysalicylidene)-1,4-diamino butane (L), in combination with Zn, have previously demonstrated their effectiveness in enhancing lanthanide NIR emission, as seen in bimetallic [L-Zn-Ln] complexes, which employs a single antenna. In this study, we present a new series of trimetallic Zn–Ln complexes, [(L-Zn)₂-Ln], featuring two compartmental ligand-Zn complexes, acting as antennas, aimed at further improving energy transfer efficiency to the lanthanide centers. Comprehensive characterization using SCXRD, PXRD, FT-IR, and CHN analyses confirmed the structural integrity of these complexes. Notably, SCXRD and XPS revealed significant structural differences between the bimetallic and trimetallic systems. The impact of the additional antenna, replacing nitrate and methanol—known contributors to nonradiative relaxation in the bimetallic [L-Zn-Ln] complexes—was thoroughly examined. Photophysical studies across both visible and NIR regions demonstrated substantial enhancements in luminescence, particularly in the NIR region, attributed to the inclusion of the second antenna, highlighting its role in improving the overall energy transfer process. © 2025 The Author(s). Chemistry - An Asian Journal published by Wiley-VCH GmbH.
Exploring ESIPT Dynamics, Aggregation, and Sensing Applications in Novel Naphthalene-Based Aroylhydrazone Luminophores Functionalized with Electron Donating and Withdrawing Groups
(American Chemical Society, 2025) Aman Rajput; Krishanu Bandyopadhyay; Sharsti Goyal; Sumit Kumar; Harshita Mehar; Satyen Saha; Rajat Walia; Abhineet Verma
Excited-State Intramolecular Proton Transfer (ESIPT) luminophores exhibit unique photophysical properties for sensing and optoelectronics. This study examines naphthalene-based aroylhydrazone derivatives (NBH-NH2 and NBH-F) to understand the impact of electron-donating (−NH2) and electron-withdrawing (-F) groups on ESIPT dynamics. Single-crystal X-ray diffraction (SCXRD) reveals differences in molecular packing and rigidity, while UV–vis absorption, fluorescence, and excitation-dependent emission studies demonstrate the observable difference in photophysical behavior. Notably, the substituent effects are profound in different DMF/Water percentages, with NBH-NH2 showing Aggregation-Induced Emission (AIE) and NBH-F displaying Aggregation-Caused Quenching (ACQ). Time-dependent density functional theory (TD-DFT) calculations provide insights into electronic structure variations during the ESIPT process. Notably, NBH-NH2 exhibits strong fluorescence and amine-induced spectral shifts, enabling real-time biogenic amine sensing for food spoilage detection. These findings establish a structure–property relationship, offering design principles for ESIPT-based materials in fluorescence sensing, optoelectronics, and food safety applications. © 2025 American Chemical Society
First report of aggregation induced emission (AIE) in NIR-II region of a Pr(III) polymer chain with pyridine-2,6-dicarboxylic acid
(Elsevier B.V., 2025) Kanishka Raghuvanshi; Abhineet Verma; Sailaja S. Sunkari
The captivating allure of lanthanide complexes, known for their NIR emissions, becomes even more mesmerizing when aggregation occurs, enhancing their luminescent properties. This novel property significantly boosts its potential for applications in theranostics, offering new opportunities for advancements. Complexation of Praseodymium (III) with pyridine-2,6-dicarboxylic acid (dipicH2) led to the formation of transparent green crystals of the 1-D polymer chain of [Pr(dipicH)(dipic)(OH2)2]·4H2O (DPr), which demonstrates this unique aggregation-induced emission in the NIR region. DipicH2 being a versatile ligand offering diverse bridging modes in connecting metal centers, numerous complexes of lanthanides exist, displaying aggregation effects in the visible spectrum. Inspite of vast number of complexes, to the best of our knowledge, this is the first report of AIE behavior in lanthanide complexes in the NIR-II region, showcasing the potential applications that may emerge for lanthanide-based materials. © 2025 Elsevier B.V.
From ACQ to AIE: The CN(π)-(π)Ar interaction driven structural and photophysical properties of aromatic ring conjugated novel diaminomaleonitrile derivatives
(Elsevier B.V., 2022) Monika; Abhineet Verma; Manish K. Tiwari; Navin Subba; Satyen Saha
Studying solid and solution state photoluminescence properties are exclusive to understanding Aggregation Caused Quenching (ACQ) and Aggregation Induced Emission (AIE) behaviour of organic molecules to explore the mechanism of molecular luminescence in greater detail. A unique hydrogen-bonded dimer with imperative interaction (CN)π—π(Ar) was designed and synthesized by selecting diaminomaleonitrile (DMN) as stator and decorated with different aromatic rotors (phenyl to pyrene). Depending on the intermolecular interaction present in the molecular system, (AIE) or (ACQ) has been observed and found to be tunable. The single-crystal x-ray diffraction analysis of these derivatives shows that AIE characteristics could be seen where to (CN)π—π(Ar) intermolecular interactions between the aromatic rotors and stator, coupled with NH––NC intermolecular hydrogen bonding is present, while the absence of these interaction reflected in ACQ observation. The significant impacts of steric, conjugation and electronic effects on the ACQ / AIE properties are presented based on crystallography analysis, optical spectra measurements and theoretical calculations. © 2022 Elsevier B.V.
Giant dielectric constant, magnetocaloric effect and spin-phonon coupling in EuTbCoMnO6 semiconductor
(Elsevier B.V., 2023) Mohd Alam; Labanya Ghosh; Srishti Dixit; Madhusmita Jena; Seema Kumari; Satya Vijay Kumar; Dheeraj Kumar; Abhineet Verma; A.K. Ghosh; Satyen Saha; R.J. Choudhary; Sandip Chatterjee
Transport, dielectric, magnetic and Raman studies of polycrystalline double perovskite EuTbCoMnO6 have been performed. Temperature-dependent resistivity follows the variable range and small polaron hopping mechanism. The temperature-dependent dielectric study shows the usual frequency-dependent step-like behavior. It also shows thermally activated relaxor peak in loss curves with giant dielectric constant near room temperature. The temperature-dependent magnetization demonstrates a second-order phase transition around 113 K. The critical behavior near the magnetic transition has been systematically investigated. The Widom scaling relation and magnetic entropy change calculation have verified the reliability of critical parameters. Maximum magnetic entropy change around the magnetic transition temperature shows the magnetocaloric effect. The estimated values of critical parameters are close to the value of the theoretical mean-field model. Temperature-dependent Raman study shows spin-phonon coupling in the system. The appearance of the magnetocaloric effect and colossal dielectric constant shows that these materials are interesting for real-life applications. © 2023 Elsevier B.V.
Good fat vs bad fat in Milk: A molecular level Understanding of Indian cow milk using confocal Raman microscopy
(Elsevier B.V., 2025) Krishanu Bandyopadhyay; Abhineet Verma; Satyen Saha
Milk, a complex fluid renowned for abundance of vitamins and immune-boosting antibodies, holds a pivotal position in human nutrition. The research delves into the fundamental constituents of milk, focusing on cis-fatty acids (cis-FA), trans-fatty acids (trans-FA), and the α-helix structure found in proteins. These constituents are instrumental in the determination of milk quality and its nutritional value. Through an analysis of Raman spectra obtained from both raw milk and its individual components, this investigation quantifies the proportional contribution of cis-FA, trans-FA, and α-helix in diverse milk samples, thereby illuminating the disparities in milk quality. An intriguing finding of the study is the progressive increase in the percentage of trans-FA within milk over time, raising concerns about its implications for milk quality and overall health. However, the research also unveils an intriguing phenomenon – heating milk can reverse the conversion of trans-FA into cis-FA, indicating the significance of temperature and time in shaping milk's composition. This research, therefore, underscores the efficacy of Raman spectroscopy in delineating the composition of milk and its evolving nature with time and temperature, providing valuable insights pertinent to both the dairy industry and consumers’ health. © 2025 Elsevier B.V.
Important role of the position of a functional group in isomers for photophysical and antibacterial properties: A case study with naphthalenemaleonitrile positional isomers
(Royal Society of Chemistry, 2020) Monika; Abhineet Verma; Supriy Verma; Nidhi Pandey; Ragini Tilak; Satyen Saha
The naphthalenemaleonitrile positional isomers, (1N: 2-amino-3-(((E)-naphthalene-1-ylmethylene)amino)maleonitrile) and (2N: 2-amino-3-(((E)-naphthalene-2-ylmethylene)amino)maleonitrile), were synthesized and then studied comparatively. Their molecular configurations exhibit an extraordinary ability to affect photophysical properties such as aggregation induced emission (AIE) and aggregation caused quenching (ACQ) properties and an unexpected structural dependence of antibacterial activity in biological cells. The 2N (naphthalene and aminomaleonitrile moieties are planar to each other) shows interesting AIE photophysical behaviours, whereas 1N (the naphthalene and aminomaleonitrile moieties are twisted around each other) exhibits the usual ACQ. The answer to the apparent contradiction of the general conception that planar molecules show ACQ in aggregates is hidden in the packing of molecules and the interactions present therein. Furthermore, 1N shows antimicrobial activity in a biological cell, whereas 2N does not. Although, the presence of a particular functional group such as imine is reported to be a determinant factor for a molecule to show antimicrobial activity, as far as is known, functional group position-dependent biological activities in aminomaleonitrile group containing molecules are not yet reported. Therefore, this report demonstrates that just the presence is not enough; the position of the functional group, which affects the structure of the molecule, is equally important. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Influence of Positional Isomerism on Modulating Crystal Packing and Physicochemical Properties of New Picolylamine-Based Fully Organic Ionic Salts
(John Wiley and Sons Inc, 2025) Supriy Verma; Amita Mahapatra; Abhineet Verma; Monika; Satyen Saha
The selective formation of positional isomers, along with the fine-tuning of physicochemical properties through structural variation, represents an effective crystal engineering strategy for the development of thermally stable and photoactive organic materials. Here in this report, three new fully organic ionic salts (namely, 2-picolylaminium p-toluenesulfonate; [2P][OTs], 3-picolylaminium p-toluenesulfonate; [3P][OTs], and 4-picolylaminium p-toluenesulfonate; [4P][OTs] based on the positional isomers of picolyl-amine as cation, and tosylate as anion have been synthesized in a single-step with atom economy at room temperature and are characterized by multinuclear NMR and HRMS techniques. Single-crystal X-ray diffraction (SCXRD) studies revealed a zig–zag fashion arrangement of cations in [2P][OTs], whereas [4P][OTs] exhibited a linear arrangement of cations within their crystal lattices. Raman spectroscopy further highlighted isomer-dependent shifts in the vibrational modes of the tosylate anions, suggesting that the positional variation of the functional group in the cation significantly influences the local ionic environment. Furthermore, the results of photophysical investigations show [3P][OTs] and [4P][OTs] are emissive in the solid state. However, [2P][OTs] do not show any visible fluorescence. The outcomes of this study emphasize the importance of positional isomerism for the rational design of desired materials. © 2025 The Author(s). ChemistrySelect published by Wiley-VCH GmbH.
Lattice Dynamics of Bi1.9Dy0.1Te3 Topological Insulator
(Elsevier B.V., 2022) Labanya Ghosh; Vinod K. Gangwar; Mahima Singh; Satya Vijay Kumar; Srishti Dixit; Abhineet Verma; Durgesh Kumar Sharma; Sudhir Kumar; S. Saha; A.K. Ghosh; Sandip Chatterjee
In this report, we have investigated the Density functional theory (DFT) calculation, temperature-dependent thermoelectric power and Raman spectroscopy of Bi1.9Dy0.1Te3 topological insulator (TI). In this system, discrepancy due to the rare earth ion Dy initiates a Red-shift in Raman active modes in the Bi2Te3 TI. Here, the lattice thermal conductivity (κL) was evaluated in the Umklapp scattering limit using the temperature dependency of the vibrational phonon modes and was used to evaluate the Figure of merit (ZT) of the system. It has been demonstrated that the estimated Power factor and ZT is very large, confirming the efficiency of Bi1.9Dy0.1Te3 for better thermoelectric and electronic applications. Such immense thermoelectric power value of the corresponding system was further supported by the DFT calculation. © 2022
Ligand influenceversuselectronic configuration of d-metal ion in determining the fate of NIR emission from LnIIIions: a case study with CuII, NiIIand ZnIIcomplexes
(Royal Society of Chemistry, 2021) Abhineet Verma; S.K.S. Hossain; Sailaja S. Sunkari; Joseph Reibenspies; Satyen Saha
Lanthanides (LnIII) are well known for their characteristic emission in the near-infrared region (NIR). However, direct excitation of lanthanides is not feasible as described by Laporte's parity selection rule. Here, we obtain NIR emission from [L-M-Ln] complexes (where, L = an organic ligand, M = a d-block metal ion, and Ln = a lanthanide ion) in which the [L-M] moiety acts as an antenna to absorb the excitation light to transfer to Ln energy levels. Based on fifteen lanthanide complexes that are presented here in which Cu, Ni and Zn complexes with a Schiff base ligand act as an antenna, we have demonstrated for the first time that electronic configuration of the d-block metal ion is very crucial for obtaining NIR emission. With Ln ion and the same ligand, Cu and Ni complexes show completely different emission than that of the corresponding NIR emitting [L-Zn-Ln] complexes. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021.