Faculty Publications
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Item A croconic acid-derived narrow band gap conjugated microporous polymer(Royal Society of Chemistry, 2023) Enoch, S.; Nipate, A.B.; Lakshmi, V.; Malakalapalli, R.R.Croconic acid, a novel highly electron-deficient building block, was introduced into a conjugated microporous polymer (CTPA). The CMP possesses strong donor-acceptor interactions, which resulted in near-IR absorption (red edge ∼1350 nm), a narrow bandgap (<1 eV) and high electrical conductivity upon doping (0.1 S m−1). Compared to the squaric acid congener (STPA), CTPA showed superior optical, electronic and electrical properties. © 2023 The Royal Society of Chemistry.Item Croconic Acid Integrated Zwitterionic Conjugated Porous Polymer for Effective Iodine Adsorption(John Wiley and Sons Ltd, 2024) Ravikumar, M.V.; Nipate, A.B.; Deyona, M.J.; Malakalapalli, M.R.; Lakshmi, V.Given the rapid growth of the nuclear sector, effective treatment of radioactive iodine is critical. Herein, we report the synthesis and the iodine adsorption properties of croconic acid (CTPB) and squaric acid (STPB) containing ?-conjugated novel zwitterionic conjugated porous polymers (CPPs). The CPPs have been synthesized through a condensation reaction of tris(4-aminophenyl)benzene with croconic acid or squaric acid in high yields (~95 %). The ionic nature of the polymers promoted high iodine/polyiodide vapour adsorption capacity of up to 4.6 g/g for CTPB and 3.5 g/g for STPB under ambient pressure at 80 °C. The zwitterionic framework (croconic acid or squaric acid units) coupled with the aromatic units is expected to effectively capture molecular iodine (I2) and polyiodides (I3? and I5?). The iodine adsorption properties of the polymers have been studied using Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Brauner-Emmett-Teller (BET) analysis, and Raman Spectroscopy. Besides this work, there are only three ionic units for effective iodine adsorption. This work demonstrates the importance of zwitterionic units in the porous network reported for iodine adsorption and separation. © 2024 Wiley-VCH GmbH.Item Functionalized 1,3-dipyrrolyl-1,3-diketone difluoroboron complexes(Royal Society of Chemistry, 2025) Shenoy, A.M.; Fernandes, P.P.; Lakshmi, V.BF2 complexes of 1,3-dipyrrolyl-1,3-diketones are highly emissive compounds and well known to be ?-electronic anion-responsive systems because of their role in the formation of ion-pair assemblies. Despite their impressive electronic properties, their broader potential remains unexplored. Here, we synthesized a series of novel mono-functionalized ?-electronic BF2 complexes of 1,3-dipyrrolyl-1,3-diketones. Controlled functionalization was achieved by selectively introducing formyl, iodo, nitro and amine groups at the ?-position of the unsubstituted pyrrole of 1,3-dipyrrolyl-1,3-diketone BF2 complexes. Single crystal X-ray diffraction studies of compounds 2 and 4 provided definitive evidence of their molecular structures and confirmed selective functionalization. Detailed photophysical and electrochemical studies revealed the alteration of electronic properties through the choice of functional groups as evidenced by distinct absorption and emission profiles. Furthermore, DFT calculations complemented the experimental findings by providing insights into the bandgap energies and molecular stability of the compounds. These functionalized BF2 complexes represent valuable building blocks for developing new derivatives with applications spanning organic electronics, bioimaging, and chemosensors. © 2025 The Royal Society of Chemistry.Item Oligopyrrole-Based Anion-Responsive ?-Electronic Systems That Exhibit Anion-Dependent Chiroptical Properties(American Chemical Society, 2025) Lakshmi, V.; Haketa, Y.; Sato, R.; Shigeta, Y.; Maeda, H.Dipyrromethane dimers linked via a boron-bridged 1,3-propanedione moiety exhibited efficient anion-binding abilities. Trifluoromethyl and pentafluorophenyl moieties substituted at the meso positions of dipyrromethane induced chirality in the ?-electronic systems, whose conformations were controlled by anion binding. Anion complexes of the oligopyrrole-based chiral ?-electronic systems exhibited anion-dependent chiroptical properties, as seen in circular dichroism. © 2025 American Chemical Society.Item Enhanced Third-Order Nonlinear Optical Response in Cross-Conjugated Pyrrole-Based ortho-Halo Arylhydrazono-?-Diketones(American Chemical Society, 2025) Jose, D.M.; Jayaraman, K.; Chidambaram, S.G.; Alnajjar, R.; Gandhiraj, V.; Lakshmi, V.The growing demand for high-performance nonlinear optical (NLO) materials has driven the development of novel organic systems with enhanced third-order NLO responses. Herein, we report the design and synthesis of a new series of ortho-halogen-substituted arylhydrazono dipyrrolyldiketones 1–4, featuring a cross-conjugated ?-system tailored to optimize the ?-electron delocalization, molecular planarity, and intramolecular charge transfer. Pyrrole substitution on the ?-diketone core was employed to redshift the electronic transitions and boost the NLO activity. Combined experimental and theoretical analyses revealed that both halogen and pyrrole modifications significantly altered the electronic polarization and third-order NLO responses. Open-aperture Z-scan measurements, performed using a 532 nm nanosecond pulsed Nd: YAG laser, revealed clear reverse saturable absorption (RSA) behavior in all four compounds. Among the series, the iodo-substituted compound 4 exhibited the highest nonlinear absorption coefficient (? = 4.51 × 10–11 m/W) and the lowest optical limiting (OL) threshold (4.85 × 1012 W/m2), confirming its superior RSA and OL performance. To the best of our knowledge, this is the first study showing that halogen engineering and pyrrole incorporation synergistically enhance RSA and OL performance in hydrazono ?-diketones, offering structure–property insights and design guidelines for advanced photonic materials. © 2025 American Chemical Society