Department of Chemistry

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

A new Tröger's base containing fluorenone organic polymer (TB-FL-COP) was synthesized and used as a fluorescence sensor for discriminative sensing of antibiotics in water. TB-FL-COP showed the highest fluorescence quenching, reversible sensing responses, and excellent sensitivity of 56 ppb level for sulfamethazine antibiotics. The Stern-Volmer quenching constant (KSV) was calculated to be 1.2 × 106 M−1. The fluorescence sensing ability was also reflected by sharp visual color changes and further demonstrated in real water samples. © 2023 The Royal Society of Chemistry

World University root node

Polymer Chemistry

Tröger's base-containing fluorenone organic polymer for discriminative fluorescence sensing of sulfamethazine antibiotic at ppb level in the water medium

A new terpyridine-4-amino-1,8-naphthalimide fluorescence sensor, TERPY-Nap, has been designed and synthesized in the analytically pure form via a one-step imidation reaction between 4-amino-1,8-naphthalic anhydride and N-[2,2′;6′,2″]Terpyridin-4′-yl-propane-1,3-diamine. The internal-charge-transfer (ICT) transition makes TERPY-Nap to be highly emissive and exhibits solvent polarity-dependent emission characteristics in different organic solvents. Inspired by the strong fluorescence, TERPY-Nap was used as an efficient fluorescence sensor for discriminative fluorescence sensing of divalent metal cations such as Cu(II), Co(II), and Ni(II) in ethanol. The initial fluorescence emission intensity of TERPY-Nap was quenched drastically upon the addition of Cu(II), Ni(II), and Co(II) ions as their nitrate salt, and the fluorescence quenching constants (KSV) were calculated to be in the order of 104–105 M−1. Furthermore, it was observed that TERPY-Nap can sense Cu(II), Ni(II), and Co(II) as low as ppb level of sensitivity and the quenched fluorescence emission of complexes can be reversed by the addition of well-known metal scavenger EDTA in ethanol. Interestingly, similar fluorescence titration studies using other metal ions like Zn(II), Cd(II), Mn(II), Ba(II), Al(III), Mg(II), and Ce(III) showed almost negligible changes in emission intensity due to their weak binding at the terpyridine receptor sites. Therefore, TERPY-Nap can be used as a potential ‘turn-off’ fluorescence chemosensor for reversible detection and trace analysis of biologically relevant and environmentally pertaining divalent metal cations. © 2023 Elsevier B.V.

Inorganica Chimica Acta

Terpyridine-4-amino-1,8-naphthalimide chemosensor for discriminative fluorescent sensing of divalent metal cations at ppb level of sensitivity

Carbon Nanodots (CNDs) generated from biomass wastes have a wide range of biological functionalities and are used in a variety of applications. Especially, the biomedical applications shown by the CNDs derived from biomass waste materials received great attention from researchers around the globe. Herein we report the synthesis of CNDs from rice husk biomass waste using a hydrothermal method. XRD pattern demonstrates the amorphous nature of CNDs with hexagonal graphite structure. Microscopic images confirmed that as-synthesized CNDs are in spherical morphology with an average size of 25–30 nm and average interplanar spacing of 0.265 nm. XPS, Raman, and FTIR spectral analyses were performed to examine the presence of functional groups and defects in CNDs. Excitation-dependent emission properties of CNDs (ФF 9.6%) were studied by UV–Vis., Contour, and fluorescence techniques. In response to the findings of the cytotoxicity experiment and the CNDs' strong emission, we carried out several biostudies to prove its importance. The CNDs possess outstanding cell viability (98%), excellent anti-inflammatory activity of 33% of LOX, 34% of COX, 45% of NO inhibition at 100 μL, significant protein denaturation (62%; IC50 20.04 μL/mL), and bright bioimaging on Zebrafish characteristics, which accentuate the perception of waste to wealth. © 2023 Elsevier B.V.

Materials Chemistry and Physics

Multipurpose biological applications of excitation-dependent fluorescent carbon nano dots emanated from biomass waste

A cleft-shaped 2-picolyl-4-amino-1, 8-naphthalimide Tröger’s base (TBNap) was synthesized and employed as a fluorescent ‘turn-on’ chemosensor for the discriminative sensing of volatile halogenated solvents based on an ICT sensing mechanism. TBNap displayed comparatively high fluorescence emission enhancement for chloroform - a potent anesthetic agent and a major constituent of tobacco smoke. The discriminative fluorescence sensing was also seen through visual color changes and was further validated using computational calculations. © 2023 The Author(s). Published by the Royal Society of Chemistry.

Sensors and Diagnostics

Discriminative ‘turn-on’ fluorescence sensing of volatile halogenated solvents using a cleft-shaped 4-amino-1, 8-naphthalimide Tröger’s base fluorophore

This article uses a mesoporous organic polymer monolithic template embedded with nanosheets of aurivillius oxide, i.e., Bi2MoO6 (BMO), as a visible light harvesting photocatalyst, for the photocatalytic dissipating for persistent organic pollutants. FE-SEM, EDAX, HR-TEM, SAED, p-XRD, UV-Vis-DRS, FT-IR, PLS, BET/BJH, and XPS analysis were performed to characterize the structural and surface morphological features of the new-age photocatalyst. The unique properties of BMO nanocomposite and a specific quantity (0.75 g) of its integration onto a translucent polymer monolith bring an innovative approach to heterogeneous photocatalysis, with photocatalytic properties far superior and more efficient than non-benign conventional methodologies. The impact of physicochemical parameters such as solution pH, photocatalyst amount, light intensity, pollutant concentration, and oxidizer dosage was evaluated to optimize the process efficacy. The BMO-0.75 dispersed polymer monolith offers superior visible light absorption and voluminous photoactive sites for the dissipation of Reactive Brown-10 (RB-10; = 99.4\%) and ciprofloxacin (CIP; = 98.7\%) at an optimized solution pH (1.0 and 6.0), photocatalyst dosage (50 and 40 mg), and photoadditives (1.0 mM KBrO3 and 1.0 mM H2O2), for RB-10 (15 ppm) and CIP (20 ppm), respectively, in = 0.3 h of irradiation, using 300 W/cm(2) tungsten lamp. The photocatalyst is reusable for several cycles without loss in efficiency and is efficient in decontaminating persistent organic pollutants at an affordable cost and time.

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY

Photoactive aurivillius oxide integrated porous polymer monoliths as renewable visible light catalyst for decontaminating persistent organic pollutants

In this work, three Co3O4 nanostructures with different morphologies (cubes, rods, and sheets) were synthesized using a hydrothermal method and tested for the CO2 hydrogenation reaction. The physicochemical properties of the structured Co3O4 were well characterized by X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) techniques. Based on the characterization, cube, rod, and sheet Co3O4 nanostructures were found to expose the (100), (110), and (112) planes, respectively. The effect of cobalt oxide morphologies with different exposed surfaces on the activity and selectivity toward CO2 hydrogenation reaction in a plug-flow reactor operated between 200 and 400 °C under atmospheric pressure conditions was explored. The results establish a correlation of the catalytic activity with morphological structures in the order rods &gt; sheets &gt; cubes. H2-TPR and XPS studies demonstrated that the high reducibility of Co3O4 rod makes it an excellent catalyst for CO2 hydrogenation. © 2023 American Chemical Society.

Journal of Physical Chemistry C

Morphology-Dependent Catalysis by Co3O4 Nanostructures in Atmospheric Pressure Carbon Dioxide Hydrogenation

Reduction of nitroarenes is a useful strategy for the preparation of aromatic amines. In this work, CuO was used as a reusable solid reagent for the reduction of nitroquinolines to aminoquinolines using hydrazine monohydrate as the hydrogen donor under mild reaction conditions. The reaction of 0.5 mmol of 5-nitroquinoline to 5-aminoquinoline was completed in 10 min with 100% conversion and selectivity. The reagent CuO could be easily collected and reused for up to four cycles, after which it is completely transformed into Cu2O and Cu. The high activity and selectivity of CuO were attributed to the facile formation of oxygen vacancies on the CuO surface under the reducing environment, as confirmed by X-ray photoelectron spectroscopy. Further, density functional theory simulations showed that oxygen vacancies led to higher adsorption (Eads = −174.4 kJ/mol) and selective activation of the nitro group (Ea = 43 kJ/mol) coupled with a reaction involving hydrogen atoms activated on the CuO surface. However, the presence of an additional pyridine ring in 5-nitroquinolines slightly impeded the rate of complete reduction (t = 10 min). © 2023 American Chemical Society.

Oxygen Vacancy-Mediated Reactivity: The Curious Case of Reduction of Nitroquinoline to Aminoquinoline by CuO

Reactions of a dimagnesium(i) compound, [{(DipNacnac)Mg}2] (DipNacnac = [HC(MeCNDip)2]−, Dip = 2,6-diisopropylphenyl), pre-activated by coordination with simple Lewis bases (4-dimethylaminopyridine, DMAP; or TMC, :C(MeNCMe)2), with 1 atmosphere of CO in the presence of one equivalent of Mo(CO)6 at room temperature, led to the reductive tetramerisation of the diatomic molecule. When the reactions were carried out at room temperature, there is an apparent competition between the formation of magnesium squarate, [{(DipNacnac)Mg}{cyclo-(κ4-C4O4)}{μ-Mg(DipNacnac)}]2 and magnesium metallo-ketene products, [{(DipNacnac)Mg}[μ-O = CC{Mo(CO)5}C(O)CO2]{Mg(D)(DipNacnac)}], which are not inter-convertible. Repeating the reactions at 80 °C led to the selective formation of the magnesium squarate, implying that this is the thermodynamic product. In an analogous reaction, in which THF is the Lewis base, only the metallo-ketene complex, [{(DipNacnac)Mg}[μ-O = CC{Mo(CO)5}C(O)CO2]{Mg(THF)(DipNacnac)}] is formed at room temperature, while a complex product mixture is obtained at elevated temperature. In contrast, treatment of a 1 : 1 mixture of the guanidinato magnesium(i) complex, [(Priso)Mg-Mg(Priso)] (Priso = [Pri2NC(NDip)2]−) and Mo(CO)6, with CO gas in a benzene/THF solution, gave a low yield of the squarate complex, [{(Priso)(THF)Mg}{cyclo-(κ4-C4O4)}{μ-Mg(THF)(Priso)}]2, at 80 °C. Computational analyses of the electronic structure of squarate and metallo-ketene product types corroborate the bonding proposed from experimental data, for the C4O4 fragments of these systems. © 2023 The Royal Society of Chemistry.

Chemical Science

Molybdenum carbonyl assisted reductive tetramerization of CO by activated magnesium(i) compounds: squarate dianion vs. metallo-ketene formation

Dioxazolones and phosphines have been used to access N-acyl iminophosphoranes in copper(I) catalysis under simple thermal conditions. The synthetic utility of this protocol is demonstrated by a broad range of substrates with an excellent atom-economy. The optimization process showed that copper demonstrated as catalytic amount toward the targeted transformation. Functionalization studies of N-acyl iminophosphoranes were also conducted. Our reaction protocol is compatible with an example of a bioactive motif-containing N-acyl iminophosphorane analogue. © 2023 Wiley-VCH GmbH.

Advanced Synthesis and Catalysis

Copper(I)-Catalyzed Decarboxylative N-Phosphorylation: Modular Preparation of N-Acyl Iminophosphoranes Using Dioxazolones and Phosphines

Organic photoredox catalysis is a versatile tool for accessing a wide range of synthetic transformations. Towards the development of a new class of organophotoredox catalysts, we have employed phenalenyl, an odd alternant hydrocarbon (OAH), for reductive C−C coupling reactions. Phenalenyl can adopt a stable open-shell state (radical), using its non-bonding molecular orbital. To date, chemically induced phenalenyl-based radicals have been extensively explored in designing various intriguing organic materials and recently towards electron transfer catalysis. However, the photochemical generation of phenalenyl-based radicals is rare. In this work, we report the photoinduced generation of phenalenyl-based radicals with detailed mechanistic studies such as steady-state absorption, time-resolved transient absorption spectroscopy and in-situ absorption kinetic experiments to authenticate the generation of photo-induced phenalenyl radicals. In addition, we present results demonstrating that this novel catalytic species can be applied to reductive pinacol coupling catalysis and reductive alkylation of terminal alkynes. © 2023 Wiley-VCH GmbH.