Faculty Publications
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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 Croconic acid-based zwitterionic conjugated porous polymer featuring nitrogen-rich triazine cores for enhanced iodine capture(Elsevier B.V., 2025) Ravikumar, M.V.; Lakshmi, V.Increased nuclear energy consumption leads to the enormous release of hazardous gases such as iodine into the environment. To address this concern, two zwitterionic Conjugated Porous Polymers (CPPs) CTTz and STTz have been synthesized by incorporating nitrogen-rich TTz with zwitterionic CA/SA under catalyst-free solvothermal conditions to achieve efficient multi-state iodine adsorption. The multiple active binding sites serve their dominance in trapping iodine species effectively. The polymers demonstrated exceptional iodine adsorption capabilities in both vapour phase and solution phases, with ?6.4 g/g and ?1.1 g/g iodine adsorption for CTTz and ?4.6 g/g and ?1.6 g/g for STTz, respectively. The zwitterionic backbones (CA/SA) in the polymer framework facilitated the formation of charge transfer complexes with iodine species, and the presence of triazine moieties enhances adsorption. The exceptional iodine capturing by CTTz and STTz lasted over a period of five cycles (?80 %). The iodine-loaded and recovered CPPs were analyzed using FTIR, FESEM, BET, XRD, and Raman spectroscopic studies, revealing the capture and release of different iodine species (I2, I3-, and I5-) by adsorbents. These findings offer valuable insights for designing and developing advanced zwitterionic adsorbent materials for effective dual-phase iodine capture and removal. Environmental implication: Uncontrolled release of radioactive iodine from nuclear energy sources poses a significant environmental and public health risk due to its volatility, mobility, and potential for bioaccumulation. Thus, it is essential to develop highly efficient, regenerable, and chemically stable adsorbents for removing iodine contamination in both vapour and solution phases. This study presents CTTz and STTz synthesised using Tris(4-aminophenyl)triazine and croconic/squaric acid building blocks, demonstrating exceptional iodine capture in both phases. Their robust structures, rich in nitrogen, oxygen and ionic binding sites, enable efficient charge-transfer complex formation with iodine species under ambient conditions. These results promote next-generation adsorbent development for nuclear waste management and provide a viable solution for preventing iodine radionuclide environmental contamination. © 2025 Elsevier B.V.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