Browsing by Author "Neelam Gupta"

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A hydrogen bond cross-linked luminescent supramolecular network polymer and its application for the detection of alkyl iodides with differentiation capabilities from aromatic iodides
(Royal Society of Chemistry, 2021) Ravi Prakash Behere; Rajlaxmi; Neelam Gupta; Susmita Roy; Ram Nayan Gautam; Manoj Kumar Bharty; Chanchal Chakroborty; Biplab Kumar Kuila
Here, we have demonstrated a luminescent network polymer through a H-bond cross-linking strategy by connecting poly(4-vinyl pyridine) chains with perylene diimide (PDI) cross-linker. The formation of a network structure through hydrogen bonding is successfully proved from the combined study of FTIR, NMR, XRD, and viscosity. The XRD study indicates improved crystallinity with an increased number of sharp reflection peaks, whereas the AFM study reveals self assembly into fibrils and sphere-like nanostructures. These network polymers have been used for the first time for fluorometric detection of a range of commonly employed alkylating agents at low concentrations. Interestingly, the network polymer can also differentiate between alkyl iodides and aromatic iodides. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021.
Donor-acceptor organic nanostructure based on conjugated polymer for improving visible-light-driven photocatalytic activity towards degradation of dye in aqueous medium
(Royal Society of Chemistry, 2022) Ravi Prakash Behere; Raj Laxmi; Neelam Gupta; Uttam Sharma; Santanu Das; Biplab Kumar Kuila
Conjugated-polymer-based donor-acceptor hybrid nanostructures have been the subject of great interest, mainly due to their potential applications in photovoltaic and other electronic and optoelectronic devices. Here, we have demonstrated a different aspect of these hybrid nanostructures toward efficient photocatalysis in an aqueous medium. The hybrid donor-acceptor nanostructures were prepared by assembling a carboxylic acid-functionalized fullerene molecule (phenyl C-61 butyric acid) (PCBA) on the surface of an amine-functionalized regioregular P3HT nanostructure through acid-base interaction. The efficient photoinduced charge separation and charge transfer in the hybrid material were investigated by steady-state and time-resolved photoluminescence and photocurrent measurements. The photocatalytic activity of the hybrid nanostructure in water under visible light irradiation (using a 20 W white LED bulb) was investigated, and it was found to show 82.5% dye degradation efficiency. To facilitate the reusability of the photocatalyst, a membrane-based dip-photocatalyst was developed from this material, and it shows 87.5% dye degradation efficiency and can be reused multiple times without a significant change in degradation efficiency. © 2022 The Royal Society of Chemistry.
Efficient Photoinduced Charge Transfer between Linear Conjugated Polymer and Polymer Network for Light Harvesting Application
(American Chemical Society, 2025) Neelam Gupta; Anamika; Arpita Maurya; Sobhan Hazra; Bhola Nath Pal; Biplab Kumar Kuila
The development of light-harvesting systems based on a donor-acceptor heterostructure for efficient conversion of light to renewable energy is an emerging area of research. Here, we have demonstrated an efficient donor-acceptor heterostructure by hybridizing a high-band gap conjugated polymer network (CPN) with a linear conjugated polymer P3HT to boost charge separation and the light-harvesting property. Steady-state and time-resolved spectroscopic studies show efficient photoinduced electron transfer from P3HT to CPN and simultaneous hole transfer from CPN to P3HT due to the proper alignment of the band gap. The light-harvesting property of the hybrid materials was demonstrated by employing the hybrids as active layers for the fabrication of all polymer photodiodes which show photodetectivity from ultraviolet A to the entire visible region with high responsivity (0.85 A/W) and detectivity of 2.41 × 1011 Jones at 620 nm and −5 V in a CPN/P3HT blend of 1:1. The repetitive on-off switching of a photodetector at zero bias clearly indicates its ability to operate in self-biased mode. This result will open up more possibilities for designing a light-harvesting system based on a high-band gap conjugated polymer network that can utilize UV and visible regions of solar light. © 2025 American Chemical Society.
Engaging a highly fluorescent conjugated polymer network for probing endogenous hypochlorite in macrophage cells: improved sensitivity via signal amplification
(Royal Society of Chemistry, 2025) Rikitha S. Fernandes; Neelam Gupta; Ch Sanjay; Anamika; Ambati Himaja; Balaram Ghosh; Biplab Kumar Kuila; Nilanjan Dey
We have employed a triazine-based conjugated polymer network (CPN) for the selective detection of hypochlorite in a semi-aqueous environment. CPNs have been widely employed in gas capture, separation, and adsorption, but the fluorescent properties of CPNs possessing extensive p-conjugated systems tend to be unexplored. Herein, we report the photophysical properties of the CPN and investigate its sensing capability towards hypochlorite. Spectroscopic investigations reveal that the CPN forms p-stacked aggregates in aqueous medium, while loose aggregates were observed to be formed in hydrophobic solvents. The fluorogenic CPN demonstrates remarkable selectivity via fluorescence quenching and a blueshift response towards hypochlorite in a semi-aqueous medium, accompanied by a color change under UV light. Such a turn-off fluorescence response, along with the blue shift upon hypochlorite sensing, was attributed to the oxidation of the sulfur atom of the thiophene functionality of the CPN, consequently resulting in suppression of Intramolecular Charge Transfer (ICT) in the corresponding oxidized adduct. The fluorescence intensity of the CPN exhibits a linear response to hypochlorite concentration, achieving a low detection limit of 1.2 nM. Furthermore, the practical applicability was demonstrated by the detection of hypochlorite in water samples and fluorescent test-paper strips. Additionally, the present system is utilized for bio-imaging of endogenous hypochlorite in RAW 264.7 cells. © 2025 The Author(s)
Enhancement of the electrochemical performance of a cathodically coloured organic electrochromic material through the formation of hydrogen bonded supramolecular polymer assembly
(Elsevier B.V., 2022) Sayan Halder; Ravi Prakash Behere; Neelam Gupta; Biplab Kumar Kuila; Chanchal Chakraborty
Herein, we have developed an H-bonded network polymer architecture with improved crystallinity and photophysical properties through a supramolecular interaction between carboxylic acid-containing perylenebisimide (PBI) cross-linker and poly(4-vinyl pyridine) (P4VP) polymer chains. The H-bonded supramolecular polymers (SMPs) are thoroughly characterized using 1H NMR, FTIR, XRD, and AFM studies. The XRD reveals higher molecular packing, long-range ordering, and better crystallinity after supramolecular assembly formation, while AFM confirms the fibril and sphere-like nanostructures in the SMP networks with decreased diameters. The long-range ordering and nanoaggregate structures in SMP benefit the network structure for better diffusion of counter ions during the redox reaction of the PBI moieties. The electrochromic (EC) measurements of the films divulge the similar reversible EC colour change of the PBI and SMP films from pristine red to deep violet along with vis-to-NIR electrochromism between the −2 V to +1 V potential sweeping along with the significant improvement of the EC parameters in SMP films compared to pristine PBI film. The colouring time (red to deep violet) is improved by 63% (5.6 s–2.2 s), while the bleaching time (deep violet to red) is speeded up by 51% (8.4 s–4.1 s) along with the increment in colouration efficiency by 50% (52.3 cm2/C to 78.1 cm2/C). Therefore, this report is very advantageous to deliver a simple and viable strategy for the enhancement of the EC parameters of organic electrochromes through the generation of ordered H-bonded polymer network formation. © 2022 Elsevier B.V.
Fluorene and Triazine-Based Conjugated Polymer Networks with Tuned Frontier Orbital Energy Levels for Improving Organic Photocatalysis
(American Chemical Society, 2024) Raj Laxmi; Anshuman; Neelam Gupta; None Anamika; Arpita Maurya; Ravi Prakash Behere; Rahul Sharma; Biswajit Maiti; Biplab K. Kuila
Here, we describe a method for fine-tuning the frontier orbital energy levels or redox potential of a conjugated polymer network (CPN) consisting of triazine and fluorene by systematically introducing electron-withdrawing groups at the fluorene moiety through simple structural modification. The band gap of CPN decreases with an increase in the strength of the electron-withdrawing group, and the relative position of the frontier orbital energy becomes more favorable for reactions like photocatalytic aerobic oxidation, which has been further confirmed by theoretical and experimental studies. The CPN with a CN group at the 9 position of fluorene (CPN3) shows the maximum photocatalytic activity (32% higher) compared to CPN1 (hydrogen at the 9 position) in white light. The best-performing catalyst CPN3 was further employed for photocatalytic reactions under white light, like the oxidation of alcohols to carbonyl and boronic acid to the corresponding alcohol, which show noteworthy characteristics like low catalyst loading, high yield, and selectivity with broad substrate scope (aliphatic, aromatic, biphenyl, and heterocyclic). CPN3 exhibited turnover frequencies of 13.33 and 10.9 mmol g-1 h-1 in 3 W blue and white LED lights, respectively, which are much higher than those of state-of-art photocatalysts. The recyclability of the catalyst was tested for up to 5 cycles without much change in the catalytic activity. The practical usefulness of the suggested method was further demonstrated by the CPN3-photocatalyzed gram-scale synthesis of high-value chemicals such as acetophenone from 1-phenylethanol and phenol from phenylboronic acid. © 2024 American Chemical Society.
Highly Fluorescent Conjugated Polymer Network as Reversible and Colorimetric Probe for Ultrafast Detection of BF3 and Amine
(American Chemical Society, 2025) None Anamika; Neelam Gupta; Arpita Maurya; Biplab Kumar Kuila
Herein, we have designed and synthesized a fluorescent conjugated polymer network (CPN) for the detection of BF3 and amine. The theoretical and photophysical study clearly indicates the presence of a twisted intramolecular charge transfer (TICT) process in the polymer resulting in strong fluorescence. Upon interacting with BF3, the probe CPN exhibited a significant “turn-off” in fluorescence and also the appearance of a broad peak around 450 nm in UV-vis absorption spectra. The probe showed high and rapid sensitivity for BF3 with a low detection limit (161 nM). Further, the CPN·BF3 complex was utilized for rapid and sensitive detection of amine, which shows “turn-on” behavior in fluorescence. Using NMR, FTIR, and density functional theory (DFT) analysis, the sensing mechanism was thoroughly confirmed. Additionally, test paper-based portable detecting devices for BF3 and volatile amines such as triethylamine in the gas phase were successfully prepared using this probe. Thus, CPN as a fluorescent probe has potential applications in chemical and industrial applications for the sensitive and selective detection of toxic species such as BF3 and amine. © 2025 American Chemical Society.
Histological changes in ovaries of mice exposed to Butea monosperma: Preliminary study; [cambios histológicos en ovarios de ratón expuestos a Butea monosperma: Estudio preliminar]
(Universidad de la Frontera, 2010) Neelam Gupta; Gajendra Singh; S.M. Singh; K.R.C. Reddy
In Ayurvedic practice Butea onosperma (Palash) is in clinical use for hundreds of years as a ontraceptive. Seeds of Butea monosperma are also used as an anthelmitic (Ansani et al., 1979) and antimicrobial (Avirutnant & Pongpan, 1983). Butea monosperma (Fabaceae family) locally known as Palash (Dhak) if given for 3 consecutive days acts as an antifertility agent for which it has been is traditionally used since time immemorial. The objective of the present study was to search the effect of Butea monosperma seeds on the ovary of mice. Observations in the present study were massive degeneration of ova in almost all the follicles, irrespective of the stage of their development. The ova from treated animals showed different stages of necrotic process. Moreover, the arrangement of follicular cells was also disturbed. The Palash seeds in the form of powder when administered orally with distilled water, according to the body weight i.e.2g/Kg, of female mice, for three consecutive days showed notable changes in ovaries. The animals were sacrificed on day next to the last day of treatment and ovaries were extirpated. varies studied histologically after Haematoxylin & Eosin staining showed most of the follicle in immature state with ndefined nucleus and nucleoli in the ovum. Others showed degenerative changes in the ovum. Follicles had lost their normal shape and arrangement and organization of granulosa cells. It was conspicuous to find that almost all follicles including graafian follicles of treated ovaries were undergoing degenerative changes simultaneously. The rate of apoptosis in the granulosa cells when studied was found increased in treated cases as compared with control. The study suggests that the disintegration of ova in the ovaries is a specific effect of Butea monosperma seed administration.
In situ palladium-doped conjugated polymer network for visible light and natural sunlight-driven Suzuki type cross-coupling reaction at room temperature
(Royal Society of Chemistry, 2024) Raj Laxmi; None Anshuman; None Anamika; Neelam Gupta; Biplab K. Kuila
Here, we describe the direct exploitation of visible light energy by using a conjugated polymer network (CPN) that is susceptible to an in situ loading of Pd metal for photocatalytic Suzuki-type C-C cross-coupling reaction. The requisite products were quantitatively achieved (yield >90%), under photo-illumination using an environment-friendly solvent. Under normal solar light, similar catalytic activity was maintained using the same experimental conditions. To comprehend the function of every variable and reactive species involved in the reaction's path, in-depth mechanistic studies were carried out. It is further underlined that the CPN has greater catalytic efficiency based on its exceptional resistance to 50 substrates of varying functionality, for 5 consecutive catalyst recycling cycles as well as bulk-scale reactions and a turnover frequency value of up to 1840 h−1 at a low catalyst dose of Pd (0.0125 mol%), while maintaining its catalytic efficacy. Its catalytic competence in terms of scope, scalability, environmental friendliness, and sustainability supports its proficiency. © 2024 The Royal Society of Chemistry.
Ni-Pd bimetallic nanoparticle stabilized polymer membrane as an efficient dip-catalyst for oxidative coupling of aromatic amines to access symmetrical and unsymmetrical azo compounds
(Royal Society of Chemistry, 2025) None Anshuman; Raj Laxmi; Padmini Gupta; Renu Mishra; Neelam Gupta; Biplab Kumar Kuila
The azo linkage is an important chemical motif with wide applications in the pharmaceutical, agrochemical, textile, paint, and food industries. The development of effective dip-catalysts that would convert aromatic amines to symmetric or asymmetric azobenzenes in the presence of aerobic molecular oxygen under mild conditions is really challenging. Here, we have developed a dip-catalyst by immobilizing poly(vinylpyrrolidone)(PVP) stabilized Ni-Pd bimetallic nanoparticles on a nylon-6 membrane through UV-crosslinking for performing such reactions. The catalyst was highly efficient for the oxidative coupling of aromatic amines to the corresponding aromatic azo compounds under aerobic conditions without employing hazardous substances or ecologically harmful nitrites. Notable reaction features include a broad substrate range (aromatic, heterocyclic, and polyaromatic amines), a high yield (∼98%), low catalyst loading, and a simple work-up method. The dip-catalyst exhibits exceptional reusability for multiple catalytic cycles while retaining its high performance and structural characteristics. The gram-scale synthesis of high-value compounds like azobenzene provided additional evidence of the practical utility of the proposed catalyst. © 2025 The Royal Society of Chemistry.
Nitrogen- and Sulfur-Enriched Conjugated Polymer Network as an Electrocatalyst for the Oxygen Reduction Reaction and as a Cathode Material for Zinc–Air Batteries
(American Chemical Society, 2025) Arpita Maurya; Neelam Gupta; Priti Singh; Nitika Bhutani; Anamika; Rik Rani Koner; Mudit Dixit; Biplab Kumar Kuila
Over the past decade, heteroatom-doped metal-free carbon materials (MFCMs) have been recognized as effective oxygen reduction reaction (ORR) catalysts. However, the active centers for the ORR in MFCMs are difficult to precisely confirm and controllably synthesize using conventional methods such as high-temperature pyrolysis or heteroatom doping. To elucidate the active center precisely and the structure–property relationship, we demonstrated a conjugated polymer network (CPN), TTB, comprising triazine, thiophene, and benzothiadiazole for ORR and as a cathode catalyst for a zinc–air battery. Density functional theory calculations revealed that the benzothiadiazole building block acts as an active center, leading to ORR catalytic activity. TTB was thoroughly characterized through different characterization techniques like FTIR, XPS, XRD, FESEM, HRTEM, and BET surface area and pore size analysis. The onset potential of 0.81 V vs reversible hydrogen electrode (RHE), diffusion-limiting current density of 3.0 mA/cm2, and E1/2of 0.68 V vs RHE with good electrochemical stability are comparable to the benchmark ORR catalyst (10% Pt/C). TTB was further used as the cathode electrocatalyst for a zinc–air battery, resulting in an open-circuit potential of 1.46 V and a specific capacity of 613 mAh g–1. A rechargeable zinc–air battery was also fabricated with TTB and RuO2as the cathode electrocatalysts, showing a voltage gap of 0.9 V and good cyclic stability. These findings show that the rational design and precise synthesis of conjugated polymer networks can facilitate the development of new ORR catalysts useful as cathode materials for zinc–air batteries. © 2025 American Chemical Society
Piezoresistive pressure sensor based on conjugated polymer framework for pedometer and smart tactile glove applications
(Elsevier B.V., 2023) Neelam Gupta; Vivek Adepu; Manav Tathacharya; Sohel Siraj; Subhradeep Pal; Parikshit Sahatiya; Biplab Kumar Kuila
Conjugated polymer frameworks which are generally less solution processable are rarely explored for flexible pressure sensor application in spite of their great potentiality that arises from three dimensional network structure, excellent conductivity, thermal stability and porosity. The report demonstrates the development of conjugated polymer framework (CPF) based flexible piezoresistive sensor and further utilization of the same for real time Pedometer and Smart Tactile Glove applications. CPF was deposited onto the cellulose paper by vacuum filtration method followed by encapsulation with PDMS to improve the flexibility and avoid the interaction of CPF with the ambient. The sensitivity of the fabricated CPF based pressure sensor was observed to be 2.92 kPa−1 with high repeatability and reliability. The transduction mechanism of the CPF based pressure sensor can be attributed to the increase in the contact areas between individual nanostructures when pressure applied and increase the current flow. The fabricated CPF-pressure sensor was further demonstrated for real time applications such as Pedometer which counts the number of steps and also Smart Tactile Glove which finds potential applications towards human machine interface. Dedicated Android applications are developed wherein the analyzed data is displayed to the user with Bluetooth as the medium of data transfer. Successful demonstration of organic materials for the use of physical sensor is a major step ahead in the field of organic electronics and opens up new avenues of research towards low-cost physical sensors for personal healthcare monitoring. © 2022 Elsevier B.V.
Polymer nanocomposite membranes and their application for flow catalysis and photocatalytic degradation of organic pollutants
(Elsevier Ltd, 2021) Rajlaxmi; Neelam Gupta; Ravi Prakash Behere; Rama Kanta Layek; Biplab Kumar Kuila
The modern world essentially needs a chemical industry that can operate with reduced production costs, and produce high-quality products with low environmental impact. The polymer nanocomposite-based flow catalytic membrane reactor where the reaction and separation can be amalgamated in one unit is considered as one of the new alternative solutions to solve these problems. In this review, we have discussed state-of-the-art flow-through catalytic reactors based on polymer nanocomposite membranes. The unique advantages of flow catalysis include uninterrupted operation, good recyclability, and reaction product without contamination that leads to simple purification. Various catalytic model reactions such as coupling, hydrogenation, esterification in the flow system are presented. We have also presented an overview of methods adopted for preparing such nanocomposite membranes. In the last section, a discussion has been made on the recent advances on polymer-based nanocomposite membranes for the degradation and separation of organic pollutants. © 2021 Elsevier Ltd
Progressive wave analysis describing wave motions in radiative magnetogasdynamics
(1991) Neelam Gupta; Vishnu D. Sharma; Bishun D. Pandey; Rishi R. Sharma
An asymptotic analysis has been carried out to study the propagation of weak nonlinear waves in radiative magnetofluids. The progressive wave theory has been used to derive an evolution equation governing the propagation of nonlinear waves. It has been solved for high-frequency domain. The solution indicates the possibility of a wave breaking after a finite time tc known as the critical time of shock formation. Effects of the thermal radiation, magnetic field, and the coupling of the thermal radiation with the magnetic field have been studied. The decay behavior of a wave with a sawtooth profile headed by a weak shock front and ending with a weak discontinuity has been investigated. © American Institute of Aeronautics and Astronautics, Inc., 1991, All rights reserved.
Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction
(American Chemical Society, 2023) Neelam Gupta; Sayan Halder; Ravi Prakash Behere; Priti Singh; Sayan Kanungo; Mudit Dixit; Chanchal Chakraborty; Biplab Kumar Kuila
Conjugated polymer frameworks (CPFs) have recently sparked tremendous research interest due to their broad potentials in various frontline application areas such as photocatalysis, sensing, gas storage, energy storage, etc. These framework materials, without sidechains or functional groups on their backbone, are generally insoluble in common organic solvents and less solution processable for further device applications. There are few reports on metal-free electrocatalysis, especially oxygen evolution reaction (OER) using CPF. Herein, we have developed two triazine-based donor-acceptor conjugated polymer frameworks by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different sidechains, alkyl and oligoethylene glycol, were rationally introduced into the 3-position of thiophene in the polymer framework to investigate the effect of side-chain functionality on the electrocatalytic property. Both the CPFs demonstrated superior electrocatalytic OER activity and long-term durability. The electrocatalytic performance of CPF2, which achieved a current density of 10 mA/cm2 at an overpotential (η) of 328 mV, is much superior to CPF1, which reached the same current density at an overpotential of 488 mV. The porous and interconnected nanostructure of the conjugated organic building blocks, which allowed for fast charge and mass transport processes, could be attributed to the higher electrocatalytic activity of both CPFs. However, the superior activity of CPF2 compared to CPF1 may be due to the presence of a more polar oxygen-containing ethylene glycol side chain, which enhances the surface hydrophilicity, promotes better ion/charge and mass transfer, and increases the accessibility of the active sites toward adsorption through lower π-π stacking compared to hexyl side chain present in CPF1. The DFT study also supports the plausible better performance toward OER for CPF2. This study confirms the promising potentiality of metal-free CPF electrocatalysts for OER and further sidechain modification to improve their electrocatalytic property. © 2023 American Chemical Society.
Side-Chain Polarity-Dependent Photoluminescence and Deep Blue Electroluminescence in Fluorene-Based Conjugated Polymer Networks
(American Chemical Society, 2025) None Anamika; Neelam Gupta; Dipanshu Sharma; Arpita Maurya; Anil Kumar; Jwohuei Huei D. Jou; Biplab Kumar Kuila
The development of solution-processable deep blue electroluminescent materials has recently attracted considerable interest in organic light-emitting diode (OLED) research. Here, we report two solution-processable, highly fluorescent, and wide band gap conjugated polymer networks (CPNs) consisting of triazine and fluorene. Two different side chains, alkyl and ethylene glycol, are introduced into the polymer backbone to investigate the effect of side-chain polarity on the fluorescence and electroluminescence properties of the polymer. The thermal, photophysical, and self-assembly properties of the polymer were studied in detail, showing high thermal stability, side-chain polarity-dependent self-assembly, and fluorescence properties in the solid state. The polymer network with an alkyl side chain shows a deep blue color, whereas the ethylene glycol side chain displays a green color. Using these polymer networks, one can create fluorescence patterns of blue and green using UV light. OLEDs based on FCPN2 with an ethylene glycol chain show a maximum quantum efficiency (EQE) of 2.7%, which is much higher than the 0.5% displayed by FCPN1 with an alkyl side chain. FCPN2 exhibits a maximum brightness of 1458 cd/m2 and a maximum current efficiency of 1.2 cd/A with deep blue emission. These findings underscore the potential of side-chain polarity to modify the fluorescence and improve the electroluminescence performance of conjugated polymer-based blue OLED devices. © 2025 American Chemical Society.
Solid Polymer Electrolyte Based on an Ionically Conducting Unique Organic Polymer Framework for All-Solid-State Lithium Batteries
(American Chemical Society, 2023) Sumana Bandyopadhyay; Neelam Gupta; Aashish Joshi; Amit Gupta; Rajiv K. Srivastava; Biplab Kumar Kuila; Bhanu Nandan
Solid polymer electrolytes (SPEs) are regarded as a potential candidate for the development of all-solid-state lithium batteries minus the safety issues related to their liquid counterparts. Poly(ethylene oxide) (PEO)-based SPEs with strong capability to dissolve lithium salts have found extensive application in lithium batteries. However, the crystalline nature and propensity of lithium dendrite growth in such SPEs have led to the search for preemptive alternatives like the incorporation of inorganic nanoparticles or porous frameworks as fillers in the polymer matrix. Herein, a unique organic polymer framework (OPF) was synthesized by the Suzuki-Miyaura coupling reaction between 2,5-dibromo-3-(2-(2-(2-ethoxyethoxy)ethoxy)ethyl)thiophene and triazine-phenyl boronic acid. Interestingly, the incorporation of long ethylene glycol side chains in the polymer framework resulted in the amorphous nature of the OPF. Impressively, the percentage of crystallinity of PEO reduced significantly to only 30% in OPF-incorporated PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) composites. Further, the side chains present in a multidirectional manner acted as an interfacial compatibilizer aiding the homogeneous distribution of OPF in the PEO matrix. The SPE showed significantly improved ionic conductivity compared to the pristine samples (9.61 × 10-3 S cm-1 at 55 °C) and a lithium-ion transference number of 0.53. The performance of such SPE was further evaluated by assembling Li/LiFePO4 (LFP) coin cells, showing a stable discharge capacity of 130 mAh g-1 at 0.2C after 200 cycles. This work provides an interesting concept for building a unique type of homogeneous OPF/PEO-based composite SPE film that can be utilized as a desirable material in solid electrolytes for lithium battery applications. © 2023 American Chemical Society.
Soluble and highly fluorescent conjugated polymer network: non-oxidative reversible doping, cell imaging and anticancer activity
(Royal Society of Chemistry, 2023) Neelam Gupta; Swapan Maity; None Anamika; Ravi Prakash Behere; Prabhash Mahata; Biswajit Maiti; Pralay Maiti; Biplab Kumar Kuila
Herein, we report two soluble and highly fluorescent triazine-based conjugated polymer networks (TCPNs) by conjugating a thiophene (donor) unit with a triazine ring (acceptor) through a phenyl linker. The 3-substituted thiophene moiety with alkyl and oligoethylene glycol side chains is rationally introduced into the polymeric network to improve its solubility and the effect of the side chain polarity on its optical, band gap, conductivity and biological activities was also investigated. When both TCPNs were reacted with a Lewis acid and base respectively, significant optical switching and a conductivity change were observed, indicating efficient non-oxidative doping/de-doping. Both TCPNs exhibit remarkable stability after several switching cycles from their neutral to doped states and vice versa. Doping of the TCPN through the addition of a Lewis acid is also studied via DFT, which clearly shows a narrowing of the band gap. To the best of our knowledge, this may be the first demonstration of the non-oxidative doping of a triazine-based CPN to control the conjugation, color and conductivity. Furthermore, these TCPNs show gelation after doping with a Lewis acid, resulting in the formation of a conducting gel. It is also observed that both TCPNs can enter cells to simultaneously exhibit abilities of fluorescence imaging and cancer cell inhibition. Thus, the described study showcases the potential scope of tuning the optical properties of triazine-based conjugated polymer networks for electronic and optoelectronic applications, as well as the probable use of these polymers for cell imaging and chemotherapeutic applications. © 2023 The Royal Society of Chemistry.
Triazine and Thiophene-Containing Conjugated Polymer Network Emitter-Based Solution-Processable Stable Blue Organic LEDs
(American Chemical Society, 2023) Neelam Gupta; Mangey Ram Nagar; Anamika; Prakalp Gautam; Biswajit Maiti; Jwo-Huei Jou; Biplab Kumar Kuila
The development of solution-processable fluorescent materials with blue electroluminescence has recently attracted considerable research interest for organic light-emitting diode (OLED) applications. Whereas, conjugated polymer frameworks (CPFs) or networks (CPNs) have attained tremendous research interest due to their vast potential in a variety of cutting-edge applications including photocatalysis, sensing, gas storage, energy storage, and so on. These framework/network materials without side chains or functional groups on their backbone are generally insoluble in common organic solvents and less solution-processable for electronic device applications. Herein, we have reported two triazine-based highly fluorescent and wide-band gap donor−acceptor conjugated polymer networks (CPNs) by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different side chains, alkyl and oligoethylene glycol, are rationally introduced into the 3-position of thiophene in the polymer network to make them solution-processable. Further physicochemical and optoelectronic characterizations of these emitters are performed in detail, and the effects of the side chain functionality and polarity on the above-mentioned properties are also thoroughly investigated. OLEDs based on these CPNs as emitters show a maximum external quantum efficiency of 2.3% with a maximum brightness of 2541 cd/m2 and a maximum current efficiency of 2.8 cd/A with blue emission [Commission Internationale de l’ećlairage (CIE) coordinates of (0.17, 0.19)]. To the best of our knowledge, this may be the first example of conjugated polymer network material emitters being successfully designed, fabricated, and tested for solution-processable blue OLEDs. These results also demonstrate the high potential of the conjugated polymer network emitters for future blue or other color OLED applications. © 2022 American Chemical Society.
Vis-to-NIR electrochromism and bright-to-dark electrofluorochromism in a triazine and thiophene-based three-dimensional covalent polymer
(Royal Society of Chemistry, 2022) Sayan Halder; Neelam Gupta; Ravi Prakash Behere; Biplab Kumar Kuila; Chanchal Chakraborty
Organic materials convey an excellent advantage in electrochromism as they exhibit moderate switching times and high colouration efficiency with a vivid colour range at a low potential window. Furthermore, conjugated polymeric frameworks (CPFs) are more superior in this regard due to their moderate surface area and porous nature. Herein, we designed and synthesized two triazine and substituted thiophene-based donor-acceptor (D-A) covalent polymeric frameworks (CPF1 and CPF2) to afford dual-performance reversible yellow-to-deep brown Vis-to-NIR electrochromism and bluish-green to quenched emission simultaneously in the +1.8 to −0.9 V potential range. The yellow-to-deep brown Vis-to-NIR electrochromism exhibited a fast switching time of 5.1 s for colouring and 8.6 s for bleaching with a high colouration efficiency of 163.7 cm2 C−1 and high optical contrast of 36%. Both CPFs exhibited excellent cycling performances with a negligible loss of optical contrast over 150 cycles. The present study describes the potential scope of the D-A based porous CPF design strategy with organic molecular materials for providing dual-performance electrochromism and electrofluorochromism, which would be useful for the next-generation smart window technology. © 2022 The Royal Society of Chemistry.