Browsing by Author "Ravi Prakash Behere"

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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.
A palladium nanoparticle implanted polymer membrane for reusable dip-catalysis of diverse C-C and C-heteroatom (O/S/N) coupling reactions
(Royal Society of Chemistry, 2023) Raj Laxmi; Ravi Prakash Behere; Arunava Manna; Biplab Kumar Kuila
The criteria for the development of a successful catalyst are simple yet cheap fabrication, high efficiency, stability, flexibility, straightforward recovery, reusability, and ease of scale-up. There are reports of palladium nanoparticle (PdNP)-based catalysts for performing carbon-carbon cross-coupling reactions, but the aforesaid criteria are rarely met in a single system. Moreover, a single catalyst system performing different types of C-C and C-heteroatom cross-coupling reactions is very rare. Herein, we achieved the above-mentioned criteria by using a reusable polymer-embedded Pd nanoparticle dip-catalyst membrane without any other ligands or additives under milder reaction conditions. The composite membrane was fabricated by simply depositing poly(4-vinyl pyridine) anchored PdNPs (average size 9.9 nm) onto a nylon-6 membrane followed by UV cross-linking. C-C bond formation reactions using diverse reagents (Suzuki-Miyaura, Heck, Sonogashira, Stille, Hiyama reactions) were achieved to give the desired products in high to excellent isolated yields, while C-X (X = N/O/S) bond formations were accomplished in moderate to good isolated yields. The turnover number (TON) and frequency (TOF) for the Suzuki-Miyaura cross-coupling reaction are calculated as ≥×104 and 3.11 s−1, respectively. The P4VP-PdNP dip-catalyst system was stable under the reaction conditions without significant leaching of Pd into the solution. The dip-catalyst membrane can be reused at least 10 times without losing any significant activity. The substrate scope for most of the cross-coupling reactions was tested, which indicates functional group tolerance and that the coupling reaction can take place with moieties having electron donating or withdrawing groups. © 2023 The Royal Society of Chemistry
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 Moisture-Induced Energy Harvesting from Water-Soluble Conjugated Block Copolymer-Functionalized Reduced Graphene Oxide
(American Chemical Society, 2021) Soumili Daripa; Koomkoom Khawas; Ravi Prakash Behere; Rampal Verma; Biplab Kumar Kuila
This Research Article demonstrates a very simple approach of a moisture-induced power-generating phenomenon using water-soluble rod-coil conjugated block copolymer (poly(3-hexythiophene)-block-poly(4-styrenesulfonic acid) (P3HT-b-PSSA)-modified reduced graphene oxide. The block copolymer-modified reduced graphene oxide (BCP-RGO) was prepared by noncovalent surface functionalization cum in situ reduction of graphene oxide. A simple device made from BCP-RGO can generate voltage upon exposure to water vapor or under different humidity conditions. The open-circuit voltage generated from the diode-like device varies with respect to the relative humidity, and the device can act as a self-powered humidity sensor. The as-prepared BCP-RGO is able to produce a maximum power density of 1.15 μW/cm2 (short-circuit current density JSC = 6.40 μA/cm2) at a relative humidity of 94%. Meanwhile, the BCP-RGO device produces a very high power density of 0.7 mW/cm2 (at a short-circuit current density of 1.06 mA/cm2) after 91% water absorption. We believe that the material presented here will be very useful for a self-biased humidity sensor and moisture-induced energy harvesting. The diode-like response of the BCP-RGO device with humidity or after water absorption will make the material applicable for self-biased humidity-controlled electronic switching. © 2021 The Authors. Published by American Chemical Society.
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.
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
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.
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.
UV Cross-Linked Polymer Stabilized Gold Nanoparticles as a Reusable Dip-Catalyst for Aerobic Oxidation of Alcohols and Cross-Aldol Reactions
(American Chemical Society, 2023) Raj Laxmi; None Anshuman; Ravi Prakash Behere; Arunava Manna; Biplab K. Kuila
In this work, a gold nanoparticle (AuNP)-embedded composite polymer membrane for dip-catalysis is developed. Primarily, a polyvinylpyrrolidone-stabilized AuNP (PVP-AuNP) with an average size of 6.50 nm was synthesized by the reduction of a composite solution of Au salt and PVP. Next, the composite membrane was fabricated by simply depositing the PVP-AuNP on the Nylon membrane followed by UV cross-linking. The composite membrane having the cross-linked PVP-AuNP was utilized as a dip-catalyst for the aerobic oxidation of alcohols to carbonyl compounds under oxygen and clean reaction conditions. The catalyst was further tested for performing cross-aldol reactions. The PVP-AuNP-catalyzed oxidation reaction also has other noteworthy characteristics, such as a low catalyst loading (Au, 1.2 mol %), high yield, and selectivity with a broad substrate scope (aliphatic, aromatic, biphenyl, and heterocyclic alcohols). The turnover number (TON) and turnover frequency (TOF) for the oxidation reaction of the alcohol are calculated to be 74.5 and 12.41 h-1, respectively. The P4VP-AuNP dip-catalysts are highly stable under the reaction conditions without significant leaching of Au into the solution. The dip-catalyst demonstrates outstanding reusability up to 10 catalytic cycles while maintaining high catalytic performance and structural features. It can be easily recovered by simply pulling it out from the reaction mixture once the reaction is complete, followed by washing and drying. The practical usefulness of the suggested method was further demonstrated by the PVP-AuNP-catalyzed gram-scale synthesis of high-value chemicals like acetophenone. Although the AuNPs are already used for different reactions, their integration into dip-catalysts for oxidation of alcohols and cross-aldol reactions with a wide substrate scope is rare. Overall, these findings demonstrate that developing composite dip-catalyst systems is a realistic strategy for creating high-value chemicals in a sustainable and environmentally friendly way. © 2023 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.