Faculty Publications
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Item Structure-property-function relationship of fluorescent conjugated microporous polymers(Royal Society of Chemistry, 2021) Bai, M.G.M.; Vignesh Babu, H.V.; Lakshmi, V.; Rajeswara Rao, M.R.Porous organic polymers (POPs) consisting of open interconnected pores offer a broad and vast accessible surface area, and thus have been explored extensively in both academia and industry for numerous applications including heterogeneous catalysis, gas separation, gas adsorption/storage, and ion exchange. Introducing the benefits of microporous polymers into the extended π-conjugated organic polymer gives rise to novel materials, namely, conjugated microporous polymers (CMPs), which endow even more intriguing properties/applications, especially in optoelectronics, energy storage, and sensors. In particular, within the domain of CMPs, luminescent CMPs enjoy the advantage of possessing aggregation-induced emission (AIE) and long-range exciton migration accompanied by the intrinsic properties such as microporosity and high surface area. The significant host-guest interactions and fast analyte diffusion facilitated by the microporous environment along with the efficient exciton migration through the polymer network will be fundamental for fast and highly sensitive chemical sensing. The unique structural features in conjunction with the selective properties and encouraging applications of the fluorescent CMPs have triggered a great deal of interest, which have led to rapid progress in the development of structurally diverse fluorescent CMPs. In this review, we present a comprehensive summary of all the advances in the development of fluorescent CMPs based on tetraphenyl ethene (TPE), phenylene, and polycyclic aromatic hydrocarbons (PAHs) and boron- A nd nitrogen-based π-systems and their emerging applications in numerous fields as well as our perspectives on future research. This journal is © the Partner Organisations.Item Structure-Property Evaluation of Knoevenagel-Derived π-Conjugated Organic Systems(John Wiley and Sons Inc, 2025) Ravikumar, M.V.; Raj, A.K.; Rajeswara Rao, M.; Lakshmi, V.π-Conjugated organic compounds display unique optical and electrical properties, rendering them appropriate for semiconducting applications. Knoevenagel condensation is one of the important reactions that facilitate the formation of olefin linkages (−C=C−) and thus has been widely employed to synthesize new π-conjugated molecules. This review summarizes the synthesis of π-conjugated compounds constructed using four novel π-conjugated moieties: diketonate/azopyrrole-BF2 complexes (BF), p-azaquinodimethane (AQM), diketopyrrolopyrrole (DPP), and barbituric acid (BA), alongside their optoelectronic features and applications in sensing, bioimaging, and photovoltaic technologies. © 2025 Wiley-VCH GmbH.Item Duration of dry and humidified incubation of single-step embryo culture medium and oxygen tension during sham culture do not alter medium composition.(F1000 Research Ltd, 2022) Adiga, S.K.; Cheredath, A.; Uppangala, S.; Asampille, G.; Lakshmi, V.; Joseph, D.; Raval, K.; Gowda, N.; Kalthur, G.Background: The extended embryo culture using single-step medium gained popularity in clinical in vitro fertilisation (IVF). However, there are concerns about the degradation of unstable medium components and their negative effects on the developing embryos. Further, dry-incubation can increase osmolality, which can in-turn enhance the concentration of constituents of the media and their stability. Hence, this study was conducted to understand the immediate changes in the culture media constituents in relation to clinically comparable situations such as single-step extended embryo culture and use of dry and humidified-incubation in two-different gaseous conditions. Methods: Commercially available single-step medium was sham-cultured in droplets under oil in two different conditions viz. dry (37°C; 6%CO 2; 5%O 2) and humidified (37°C; 6% CO 2; atmospheric O 2) for 0h, 72h, and 120h intervals. Droplets were subjected to the sensitivity-enhanced nuclear magnetic resonance (NMR)-based profiling using 800 MHz NMR equipped with a cryogenically cooled micro-coil (1.7mm) probe. NMR profile of the embryo culture medium between the two groups were comprehensively assessed. Results: A total of ten amino acids and four energy substrates were identified from the culture medium. The medium constituents identified showed a non-significant increase in the dry-incubation group at 72h and then declined at 120h. Humidified incubation had no effects on the level of the identified medium constituents until 120h. No significant differences in the levels of medium constituents identified were observed between the dry and humidified-groups at various time-points tested. Conclusions: A non-significant variation in the levels of medium constituents observed in the dry-incubation of single-step medium most unlikely to influence a clinical outcome. However, the impact of these subtle changes on the (epi)genetic integrity of the embryos in a clinical set-up to be addressed. © 2022 Cheredath A et al.Item Duration of dry and humidified incubation of single-step embryo culture medium and oxygen tension during sham culture do not alter metabolomics signature(NLM (Medline), 2022) Cheredath, A.; Uppangala, S.; Asampille, G.; Lakshmi, V.; Joseph, D.; Raval, K.; Gowda G A, N.; Kalthur, G.; Adiga, S.K.Background: The extended embryo culture using single-step medium gained popularity in clinical in vitro fertilisation (IVF). However, there are concerns about the degradation of unstable medium components and their negative effects on the developing embryos. Further, dry-incubation can increase osmolality, which can in-turn enhance the concentration of constituents of the media and their stability. Hence, this study was conducted to understand the immediate changes in the culture media metabolites in relation to clinically comparable situations such as single-step extended embryo culture and use of dry and humidified-incubation in two-different gaseous conditions. Methods: Commercially available single-step medium was sham-cultured in droplets under oil in two different conditions viz. dry (37°C; 6%CO 2; 5%O 2) and humidified (37°C; 6% CO 2; atmospheric O 2) for 0h, 72h, and 120h intervals. Droplets were subjected to the sensitivity-enhanced nuclear magnetic resonance (NMR)-based profiling using 800 MHz NMR equipped with a cryogenically cooled micro-coil (1.7mm) probe. Metabolomic signatures between the two groups were comprehensively assessed. Results: A total of ten amino acids and four energy substrates were identified from the culture medium. Metabolite levels showed a non-significant increase in the dry-incubation group at 72h and then declined at 120h. Humidified incubation had no effects on the level of the metabolite until 120h. No significant differences in the levels of metabolites were observed between the dry and humidified-groups at various time-points tested. Conclusions: A non-significant variation in the levels of metabolites observed in the dry-incubation of single-step medium most unlikely to influence a clinical outcome. However, the impact of these subtle changes on the (epi)genetic integrity of the embryos in a clinical set-up to be addressed. ©: © 2022 Cheredath A et al.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 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