Browsing by Author "Krishanu Bandyopadhyay"

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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.
Diverse Self-Assembled Molecular Architectures Promoted by C-H···O and C-H···Cl Hydrogen Bonds in a Triad of α-Diketone, α-Ketoimine, and an Imidorhenium Complex: A Unified Analysis Based on XRD, NEDA, SAPT, QTAIM, and IBSI Studies
(American Chemical Society, 2024) Ankita Sinha; Suphal Sen; Tejender Singh; Aniruddha Ghosh; Satyen Saha; Krishanu Bandyopadhyay; Arindam Dey; Suparna Banerjee; Jaydip Gangopadhyay
X-ray structural elucidation, supramolecular self-assembly, and energetics of existential noncovalent interactions for a triad comprising α-diketone, α-ketoimine, and an imidorhenium complex are highlighted in this report. Molecular packing reveals a self-assembled 2D network stabilized by the C-H···O H-bonds for the α-diketone (benzil), and the first structural report of Brown and Sadanaga stressing on the prevalence of only the van der Waals forces seems to be an oversimplified conjecture. In the α-ketoimine, the imine nitrogen atom undergoes intramolecular N···H interaction to render itself inert toward intermolecular C-H···N interaction and exhibits two types of C-H···O H-bonds in consequence to generate a self-assembled 2D molecular architecture. The imidorhenium complex features a self-aggregated 3D packing engendered by the interplay of C-H···Cl H-bonds along with the ancillary C-H···π, C···C, and C···Cl contacts. To the best of our knowledge, in rhenium chemistry, this imidorhenium complex unravels the first example of self-associated 3D molecular packing constructed by the directional hydrogen bonds of C-H···Cl type. The presence of characteristic supramolecular synthons, viz., R22(12), R22(16), and R22(14), in the α-diketone, α-ketoimine, and imidorhenium complex, respectively, has prompted us to delve into the energetics of noncovalent interactions. Symmetry-adapted perturbation theory analysis has authenticated a stability order: R22(14) > R22(12) > R22(16) based on the interaction energy values of −25.97, −9.93, and −4.98 kcal/mol, respectively. The respective average contributions of the long-range dispersion, electrostatic, and induction forces are 58.5, 32.8, and 8.7%, respectively, for the intermolecular C-H···O interactions. The C-H···Cl interactions experience comparable contribution from the dispersion force (57.9% on average), although the electrostatic and induction forces contribute much less, 28.0 and 14.1%, respectively, on average. The natural energy decomposition analysis has further attested that the short-range, interfragment charge transfer occurring via the lp(O/Cl) → σ*(C-H) routes contributes 17-25% of the total attractive force for the C-H···O and C-H···Cl interactions. Quantum theory of atoms in molecules analysis unfolds a first-order exponential decay relation (y = 8.1043e-x/0.4095) between the electron density at the bond critical point and the distance of noncovalent interactions. The distances of noncovalent interactions in the lattices are internally governed by the individual packing patterns rather than the chemical nature of the H-bond donors and acceptors. Intrinsic bond strength index analysis shows promise to correlate the electron density at BCP with the SAPT-derived interaction energy for the noncovalent interactions. Two factors: (i) nearly half the HOMO-LUMO energy difference for the imidorhenium complex (∼30 kcal/mol) compared to the organics, and (ii) ∼60% localization of HOMO over the mer-ReCl3 moiety clearly indicate an enhanced polarizability of the complex facilitating the growth of weak C-H···Cl H-bonds. © 2024 The Authors. Published by American Chemical Society.
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
Exploring the Gamma-Ray Enhanced NIR-Luminescence and Cytotoxic Potential of Lanthanide-Naphthalene Dicarboxylate based Metal–Organic Frameworks
(Springer, 2024) Podilapu Atchutha Rao; Harihara Padhy; Krishanu Bandyopadhyay; Adapaka Venkateswara Rao; Ravikumar Ganta; Samatha Bevara; Bheeshma Pratap Singh; Bhavani Kundrapu; Satyen Saha; RamaRao Malla; Saratchandra Babu Mukkamala
In this investigation, we explore the integration of lanthanides into Metal–Organic Frameworks (MOFs) to enable Near-Infrared (NIR) emission. Specifically, we focus on Lanthanide-Naphthalene Dicarboxylate based MOFs (Ln-MOFs), incorporating elements such as Praseodymium (Pr), Samarium (Sm), Dysprosium (Dy), and Erbium (Er). The synthesis of Ln-MOFs is achieved via the hydrothermal method. The structure, morphology, thermal stability, and luminescence properties of synthesized Ln-MOFs have been evaluated through different characterization techniques. Upon photoexcitation at 350 nm, Ln-MOFs show the emission in the Visible and NIR region. Further, the luminescence intensity of Ln-MOFs enhanced by 2–3 folds in the visible region and 6–8 folds in NIR region after exposing to Gamma irradiation at 150 kGy. Cytotoxic effect on the viability of MDA-MB 231 and MDA-MB 468 Triple negative breast cancer (TNBC) cells was evaluated by MTT assay. The results revealed that among all synthesized MOFs, Pr-MOF exhibited an aggressive cytotoxic effect. Additionally, analysis of phase-contrast microscopy data indicates that Pr-MOF induces alterations in the morphology of both MDA-MB 231 and MDA-MB 468 TNBC cells when compared to untreated controls. The findings in this study reveal the utilization of Ln-MOFs for studying cytotoxicity and highlight their ability to enhance near-infrared (NIR) emission when exposed to gamma radiation. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Exploring the Gamma-Ray Enhanced NIR-Luminescence and Cytotoxic Potential of Lanthanide-Naphthalene Dicarboxylate based Metal–Organic Frameworks
(Springer, 2025) Podilapu Atchutha Rao; Harihara Padhy; Krishanu Bandyopadhyay; Adapaka Venkateswara Rao; Ravi Kumar Ganta; Samatha Bevara; Bheeshma Pratap Singh; Bhavani Kundrapu; Satyen Saha; Rama Rao Malla; Saratchandra Babu Mukkamala
In this investigation, we explore the integration of lanthanides into Metal–Organic Frameworks (MOFs) to enable Near-Infrared (NIR) emission. Specifically, we focus on Lanthanide-Naphthalene Dicarboxylate based MOFs (Ln-MOFs), incorporating elements such as Praseodymium (Pr), Samarium (Sm), Dysprosium (Dy), and Erbium (Er). The synthesis of Ln-MOFs is achieved via the hydrothermal method. The structure, morphology, thermal stability, and luminescence properties of synthesized Ln-MOFs have been evaluated through different characterization techniques. Upon photoexcitation at 350 nm, Ln-MOFs show the emission in the Visible and NIR region. Further, the luminescence intensity of Ln-MOFs enhanced by 2–3 folds in the visible region and 6–8 folds in NIR region after exposing to Gamma irradiation at 150 kGy. Cytotoxic effect on the viability of MDA-MB 231 and MDA-MB 468 Triple negative breast cancer (TNBC) cells was evaluated by MTT assay. The results revealed that among all synthesized MOFs, Pr-MOF exhibited an aggressive cytotoxic effect. Additionally, analysis of phase-contrast microscopy data indicates that Pr-MOF induces alterations in the morphology of both MDA-MB 231 and MDA-MB 468 TNBC cells when compared to untreated controls. The findings in this study reveal the utilization of Ln-MOFs for studying cytotoxicity and highlight their ability to enhance near-infrared (NIR) emission when exposed to gamma radiation. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
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.
Harnessing conformational changes in TAM for enhanced photophysical properties leading to biological applications
(Elsevier Ltd, 2025) Soumya Singh; Krishanu Bandyopadhyay; Vivek Kumar Sharma; Biplob Koch; Satyen Saha
Triarylmethanes (TAMs) are particularly notable for their medicinal potential and are being investigated for their structure, photophysical characteristics, and applications. However, the suboptimal photophysical properties of TAMs limit their practical applications, highlighting the need for further optimization. In light of this, the present study synthesizes flexible (F) and conformationally rigid xanthene (R) derivatives of TAM through Friedel-Crafts alkylation and investigated their photophysical properties. The investigation reveals the enhanced photophysical properties of R-derivative as compared to F-derivative. Additionally, the biological applications of R were examined including its interactions with CT-DNA, where it exhibited high binding affinity. Moreover, cytotoxicity assays performed on RAW 264.7 macrophage cell lines and HeLa cells (cervical cancer cell line) using Rhodamine B (RhB) as a standard showed low toxicity and similar biocompatibility. Furthermore, in vitro cellular imaging revealed that R exhibited significantly higher fluorescence intensity than RhB. The outcome of this study offers valuable insights paving the way for the broader use of TAM derivatives in therapeutic and diagnostic fields. © 2025 Elsevier Ltd
Metal-Free α-Sulfonylation of β-Ketothioamides: Access to α-Sulfonyl-β-Ketoamides and their Photophysical Studies
(John Wiley and Sons Inc, 2025) Vipin Kumar; Monish Arbaz Ansari; Anup Kumar Yadav; Saurabh Singh; Krishanu Bandyopadhyay; Satyen Saha; Maya Shankar Singh
Herein, we report a metal and additive-free unprecedented reactivity of β-ketothioamides with sulfonyl chlorides for the synthesis of previously unreported 2-sulfonyl-3-oxo-N,3-diarylpropanamides via in situ thioamide to amide conversion followed by dehydrohalogenative C−S cross-coupling at room temperature under an open air for the first time. The protocol demonstrates not only its operational simplicity, efficiency, mild condition, and scalability, but also easy to get the diverse a-sulfonyl-β-ketoamides in good to high yields. Additionally, the DFT and photophysical studies supported the proposed mechanism, and revealed unique excitation-dependent emission coupled with ESPT for the synthesized sulfones. © 2024 Wiley-VCH GmbH.
Observation of the multiple magnetic phases in double perovskite Pr1.8La0.2CoFeO6
(Elsevier B.V., 2024) Dheeraj Kumar; Prajyoti Singh; Mohd Alam; Satya Vijay Kumar; Srishti Dixit; Krishanu Bandyopadhyay; G.D. Dwivedi; Satyen Saha; A.K. Ghosh; Sandip Chatterjee
The structural and magnetic properties of the double perovskite Pr1.8La0.2CoFeO6 have been investigated. The X-ray diffraction study shows that the system acquires room-temperature orthorhombic phase with the Pnma space group. The X-ray photoemission spectroscopy (XPS) measurement confirmed that the B-site ions are present in mixed valence states i.e. Co has been found in Co2+ and Co3+ valance states whereas Fe has been found in Fe3+/Fe4+. Magnetic measurements of the system confirm the existence of several fascinating magnetic behaviors, such as long-range canted antiferromagnetism withTN ∼ 271 K, giant exchange bias, and re-entrant cluster glass phase (TG ∼ 33 K). Field-dependent magnetization shows a large spontaneous exchange bias; HSEB∼ 1.8 kOe and giant conventional exchange bias, HCEB∼ 2.4 kOe at 5 K. Antiferromagnetic materials with large exchange bias can be utilized in high-density spintronic devices. Temperature-dependent Raman study demonstrates that the observed phonon mode exhibits anomalous behavior close to the magnetic transition temperature. Analysis of anomalous softening of phonon mode below TN, clarifies the presence of significant spin-phonon coupling while the magnetostriction effect does not play any significant role in the observed phonon anomaly. © 2024
Raman effect and unusual transport properties of Co-doped Mn2FeAl Heusler alloy
(Institute of Physics, 2023) Srishti Dixit; Swayangsiddha Ghosh; Neha Patel; Mohd Alam; Krishanu Bandyopadhyay; Nisha Shahi; Yogendra Kumar; M. Sawada; K. Shimada; Satyen Saha; Sanjay Singh; Sandip Chatterjee
Semiconducting materials with a distinctive blend of high electrical and low thermal conductivity are required for efficient thermoelectric devices. In this aspect, Heusler alloys are potential candidates for thermoelectric materials. It has been observed that Co doping in Mn2FeAl enhances the electrical conductivity as well as reduces the thermal conductivity of the system leading to an improvement in figure of merit. The Seebeck coefficient suggested the p-type behavior over the whole temperature range, followed by a maximum at 150 K. Additionally, the electronic properties of the suggest that the observed Raman mode is due to the electronic excitations in the system. Interestingly, this system shows a decoupling between the Seebeck coefficient and electrical conductivity, suggesting the promising potential of as a thermoelectric material and offering valuable insights into its electronic properties. Copyright © 2024 EPLA.
Recent advances in NIR-II emitting nanomaterials: design and biomedical applications of lanthanide complexes and functionalized mesoporous silica nanoparticles (MSNs)
(Royal Society of Chemistry, 2025) Krishanu Bandyopadhyay; Snigdha Singh; Vivek K. Chaturvadi; Anurag Kumar Singh; Abhineet Verma
The second near-infrared (NIR-II, 1000-1700 nm) region has gained significant attention due to its superior tissue penetration depth, reduced photon scattering, and minimal autofluorescence compared to the first near-infrared (NIR-I, 700-900 nm) window. These advantages make NIR-II an ideal spectral range for bioimaging, photothermal therapy (PTT), and photodynamic therapy (PDT). Various nanomaterials, including metal-based complexes, organic dyes, and carbon-based materials, have been engineered to serve as efficient NIR-II agents for enhanced biomedical applications. Among these, mesoporous silica nanoparticles (MSNs) have emerged as versatile nanoplatforms due to their tunable porosity, high surface area, and biocompatibility. MSNs can be modified with different functional materials, such as luminescent coordination complexes, organic dyes, and metal nanoclusters, to optimize photothermal conversion efficiency and imaging capabilities. Their ability to encapsulate therapeutic agents further enables controlled drug delivery and combinational cancer therapies. Additionally, hybrid MSN systems incorporating nanocarbon materials (e.g., fullerenes, carbon nanotubes) and metal nanoparticles have been explored to enhance stability and bioavailability. Despite their promising potential, challenges such as long-term biocompatibility, clearance mechanisms, and precise targeting remain key hurdles in clinical translation. Future research should focus on overcoming these limitations by developing next-generation MSN-based nanocomposites, such as MSN-graphene oxide, MSN-fullerenes, MSN-carbon nanotubes, MSN-quantum dots, and MSN-metal nanoparticles. These advancements will pave the way for improved therapeutic efficacy and broader biomedical applications. © 2025 The Royal Society of Chemistry.
TBHP-Mediated Intermolecular Radical Coupling and Intramolecular Cyclization Cascade: Access to Furo[2,3-b]quinoxalines and Their Photophysical Study
(John Wiley and Sons Inc, 2024) Subhasish Ray; Vipin Kumar; Saurabh Singh; Krishanu Bandyopadhyay; Satyen Saha; Maya Shankar Singh
A cascade one-pot strategy to construct 31 examples of furo-fused quinoxalines in up to 88% yields has been devised from readily accessible β-ketothioamides and quinoxalin-2-ones in open flask at room temperature under TBHP mediated conditions. Mechanistic studies revealed that the overall reactivity relies on the seamless integration of intermolecular radical coupling and intramolecular cyclization via desulfhydration of C=S bond cleavage. Generation of H2S as the only by-product makes this process highly attractive. Furthermore, the photophysical behavior of the furo-fused quinoxalines has also been studied. © 2023 Wiley-VCH GmbH.
The crucial role of stability of intercalating agent for DNA binding studies in DMSO/water system
(Elsevier B.V., 2024) Krishanu Bandyopadhyay; Abhineet Verma; Ankita Pandey; Rajat Walia; Satyen Saha
In recent years, extensive research has been directed towards understanding the interactions between various zinc complexes with DNA, specifically delving into their intercalation and binding behaviors. The binding of zinc complexes to DNA is particularly intriguing due to their distinctive intercalating capabilities. This study unveils a remarkable phenomenon observed with a specific Zn complex, ([B-Zn-N3], where B is a Schiff base ligand), during DNA intercalation investigations in the popular DMSO-Water binary solvent mixture. An unanticipated observation revealed time-dependent changes in the UV–visible absorption spectroscopic studies, coupled with the existence of an isosbestic point. This observation questions the stability of the intercalating agent itself during the intercalation process. The emergence of a decomposed product during the intercalation study has been confirmed through various analytical techniques, including CHN analysis, MALDI mass, XPS, Raman spectroscopy, and Powder XRD. The change in the chemical species on intercalation is further substantiated by theoretical studies, adding depth to our understanding of the intricate dynamics at play during DNA intercalation with the [B-Zn-N3] complex in the DMSO-Water system. © 2024 Elsevier B.V.
Unveiling aggregation concentration in surfactants and ionic liquids using confocal Raman and hyper-Raman spectroscopies
(Elsevier B.V., 2025) Krishanu Bandyopadhyay; Abhineet Verma; Neeraj Singh Rawat; Surajit Maity; Hirotsugu Hiramatsu; Satyen Saha
A key characteristic property of Ionic liquids (ILs) is their tendency to form nano-scale aggregates, that sets them apart from other liquid materials. While methods like conductance and surface tension measurements are commonly used to determine aggregation of surfactants, they often come with significant limitations when employed for ILs. Although the aggregation behavior of ILs has been studied for the last decade, accurately determining their critical ionic liquid aggregation concentration (CILAC, first proposed by Saha and coworkers, ChemistrySelect, 2019, 4, 49–58) remains a challenging task. Here in this study, a Raman signature band of networked water molecules is used to study the aggregation of IL in a 20 % ethanol in water binary mixture. This study examines how the hydrogen bonding interactions influence the aggregation of ILs such as [C1Cnmim][Cl] (with n = 4, 6, 8, and 10) and surfactants like CTAB, SDS, and TX-100. This report introduces Raman and Hyper Raman spectroscopy as a novel method for determining aggregation concentration, where traditional techniques like the conductivity measurement method fails. © 2025
Water in ionic liquids: Raman spectroscopic studies
(John Wiley and Sons Ltd, 2022) Satyen Saha; Abhineet Verma; Krishanu Bandyopadhyay
The application of Raman spectroscopy in studies of ionic liquid (IL) systems having water is presented here. The presence of water can be intentional or unintentional. Since water severely affects IL's physical and chemical properties, it is very important not only to identify but also to understand the role of water. It will be evident from this short review that Raman spectroscopy has immensely helped to understand the IL/water mixture at the molecular level. © 2022 John Wiley & Sons Ltd.