Browsing by Author "Shetti, V.S."

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Chemical syntheses and salient features of azulenecontaining homo- And copolymers
(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2021) Shetti, V.S.
Azulene is a non-alternant, aromatic hydrocarbon with many exciting characteristics such as having a dipole moment, bright color, stimuli responsiveness, anti-Kasha photophysics, and a small HOMO-LUMO gap when compared to its isomer, naphthalene. These properties make azulene-containing polymers an intriguing entity in the field of functional polymers, especially for organic electronic applications like organic field-effect transistors (OFET) and photovoltaic (PV) cells. Since azulene has a fused five and seven-membered ring structure, it can be incorporated onto the polymer backbone through either of these rings or by involving both the rings. These azulene-connection patterns can influence the properties of the resulting polymers and the chemical synthesis in comparison to the electrochemical synthesis can be advantageous in obtaining desired patterns of substitution. Hence, this review article presents a comprehensive overview of the developments that have taken place in the last three decades in the field of chemical syntheses of azulene-containing homo- and copolymers, including brief descriptions of their key properties. © 2021 Beilstein-Institut Zur Forderung der Chemischen Wissenschaften. All rights reserved.
Chemical syntheses and salient features of azulenecontaining homo- And copolymers
(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2021) Shetti, V.S.
Azulene is a non-alternant, aromatic hydrocarbon with many exciting characteristics such as having a dipole moment, bright color, stimuli responsiveness, anti-Kasha photophysics, and a small HOMO-LUMO gap when compared to its isomer, naphthalene. These properties make azulene-containing polymers an intriguing entity in the field of functional polymers, especially for organic electronic applications like organic field-effect transistors (OFET) and photovoltaic (PV) cells. Since azulene has a fused five and seven-membered ring structure, it can be incorporated onto the polymer backbone through either of these rings or by involving both the rings. These azulene-connection patterns can influence the properties of the resulting polymers and the chemical synthesis in comparison to the electrochemical synthesis can be advantageous in obtaining desired patterns of substitution. Hence, this review article presents a comprehensive overview of the developments that have taken place in the last three decades in the field of chemical syntheses of azulene-containing homo- and copolymers, including brief descriptions of their key properties. Â© 2021 Beilstein-Institut Zur Forderung der Chemischen Wissenschaften. All rights reserved.
Conformationally rigid, Ï€-extended annulated porphyrinoids derived from the naphthobipyrrole motif
(Royal Society of Chemistry, 2022) Shetti, V.S.
Ï€-Extension in porphyrinoids can be achieved by fusing additional aromatic rings onto the macrocycle's periphery and such porphyrinoids are referred to as annulated porphyrinoids. Annulated porphyrinoids display contrasting properties in comparison with their non-annulated congeners. While an annulation strategy can create Ï€-extended systems, the simultaneous incorporation of conformational rigidity in such porphyrinoids can ensure that they adopt a planar structure, and the advantages associated with the extended Ï€-network can be leveraged. Hence, while synthesizing such porphyrinoids, judicial selection of the precursor becomes important. The ease of synthesis and the presence of a Î²-Î²â€²-linked o-phenylene bridge qualify 3,8-1,10-dihydrobenzo[e]pyrrolo[3,2-g]indole, commonly known as naphthobipyrrole, to be one such precursor suitable for the synthesis of conformationally rigid annulated porphyrinoids. This field of study has started to bloom only in the last decade and the examples reported so far are confined to the naphtho-versions of porphycenes (isomeric porphyrin), a few members of the aromatic/antiaromatic expanded porphyrinoids, and calix[n]bipyrroles. In view of this, the current review article aims to summarize the up-to-date developments in this area and discusses the synthesis, structure, and properties of the reported naphthobipyrrole-derived annulated porphyrinoids. Â© 2022 The Royal Society of Chemistry.
Conformationally rigid, π-extended annulated porphyrinoids derived from the naphthobipyrrole motif
(Royal Society of Chemistry, 2022) Shetti, V.S.
π-Extension in porphyrinoids can be achieved by fusing additional aromatic rings onto the macrocycle's periphery and such porphyrinoids are referred to as annulated porphyrinoids. Annulated porphyrinoids display contrasting properties in comparison with their non-annulated congeners. While an annulation strategy can create π-extended systems, the simultaneous incorporation of conformational rigidity in such porphyrinoids can ensure that they adopt a planar structure, and the advantages associated with the extended π-network can be leveraged. Hence, while synthesizing such porphyrinoids, judicial selection of the precursor becomes important. The ease of synthesis and the presence of a β-β′-linked o-phenylene bridge qualify 3,8-1,10-dihydrobenzo[e]pyrrolo[3,2-g]indole, commonly known as naphthobipyrrole, to be one such precursor suitable for the synthesis of conformationally rigid annulated porphyrinoids. This field of study has started to bloom only in the last decade and the examples reported so far are confined to the naphtho-versions of porphycenes (isomeric porphyrin), a few members of the aromatic/antiaromatic expanded porphyrinoids, and calix[n]bipyrroles. In view of this, the current review article aims to summarize the up-to-date developments in this area and discusses the synthesis, structure, and properties of the reported naphthobipyrrole-derived annulated porphyrinoids. © 2022 The Royal Society of Chemistry.
Cost-effective bio-derived mesoporous carbon nanoparticles-supported palladium catalyst for nitroarene reduction and Suzuki Miyaura coupling by microwave approach
(2020) Supriya, S.; Ananthnag, G.S.; Shetti, V.S.; Nagaraja, B.M.; Hegde, G.
A new heterogeneous catalyst was synthesized by immobilizing Pd on areca nut kernel-derived carbon nanospheres (CNSs). The CNSs, without any further activation processes, accommodated 3% of Pd on their surface. The new Pd/CNS material was used for the reduction of nitroarenes and Suzuki Miyaura coupling of bromoarenes with aryl boronic acids. The reactions were conducted under microwave irradiation at 160 C using 12 mol% of Pd/CNS (0.36% actual Pd content). The reduction of nitroarenes into their respective amino compounds was achieved in 10 20 min (conversion up to 100%); by contrast, the Suzuki Miyaura reactions yielded up to 98% at 150 C with 10 mol% of Pd/CNS catalyst. The products were identified using gas chromatography and nuclear magnetic resonance spectroscopy. The catalyst was isolated from reaction mixture and reused without any significant loss in the activity. Thus, the present work introduces one-pot-derived porous CNSs as efficient catalytic support to Pd, establishing an alternative to existing Pd/C in terms of cost and efficiency. 2020 John Wiley & Sons, Ltd.
Cost-effective bio-derived mesoporous carbon nanoparticles-supported palladium catalyst for nitroarene reduction and Suzuki–Miyaura coupling by microwave approach
(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2020) Supriya, S.; Ananthnag, G.S.; Shetti, V.S.; Nagaraja, B.M.; Hegde, G.
A new heterogeneous catalyst was synthesized by immobilizing Pd on areca nut kernel-derived carbon nanospheres (CNSs). The CNSs, without any further activation processes, accommodated 3% of Pd on their surface. The new Pd/CNS material was used for the reduction of nitroarenes and Suzuki–Miyaura coupling of bromoarenes with aryl boronic acids. The reactions were conducted under microwave irradiation at 160 °C using 12 mol% of Pd/CNS (0.36% actual Pd content). The reduction of nitroarenes into their respective amino compounds was achieved in 10–20 min (conversion up to 100%); by contrast, the Suzuki–Miyaura reactions yielded up to 98% at 150 °C with 10 mol% of Pd/CNS catalyst. The products were identified using gas chromatography and nuclear magnetic resonance spectroscopy. The catalyst was isolated from reaction mixture and reused without any significant loss in the activity. Thus, the present work introduces one-pot-derived porous CNSs as efficient catalytic support to Pd, establishing an alternative to existing Pd/C in terms of cost and efficiency. © 2020 John Wiley & Sons, Ltd.
Meso-tris(2-furyl/2-thienyl) substituted porphyrin-ferrocene ‘click’ conjugates: synthesis, experimental, and computational studies
(Royal Society of Chemistry, 2024) Shet, S.N.; Patil, M.; Shetti, V.S.
The chemical synthesis of 5-(4-azidophenyl)-10,15,20-tris(2-furyl/2-thienyl)porphyrins and their utilization in a Cu(i) catalyzed alkyne-azide ‘click’ reaction (CuAAC) with ethynylferrocene to obtain the hitherto unknown meso-tris(2-furyl/2-thienyl) substituted porphyrin-ferrocene ‘click’ conjugates are reported. These new ‘click’ conjugates were studied along with the reference ‘click’ conjugates containing all-meso-aryl substituted porphyrins by experimental and computational methods. Compared to the reference, the new conjugates displayed red-shifted absorption/emission bands, easier porphyrin ring reduction, and an efficient photoinduced electron transfer (PET) process from ferrocene to a porphyrin unit. Density functional theory (DFT) calculations performed on these conjugates revealed a good correlation with the experimental results. © 2024 The Royal Society of Chemistry.
Polydopamine functionalized halloysite nanotubes incorporated polyethersulfone hollow fiber membranes for the removal of arsenic (as-v) from water
(Iranian Research Organization for Science and Technology, 2025) Mruthyunjaya, S.D.; Isloor, A.M.; Nayak, S.S.; Venkatesh, M.; Shetti, V.S.
Polyethersulfone (PES) based hollow fiber membranes containing polydopamine-functionalized halloysite nanotubes (FHNTs) were fabricated in different concentrations employing a dry-wet approach and using phase inversion methodology. Thus, the prepared nanocomposite hollow fiber membranes were characterized using FE-SEM (Field Emission Scanning Electron Microscopy), AFM (Atomic Force Microscopy), ATR-IR, Zeta Potential, and contact angle for studying membrane surface morphology, topography, presence of functional groups, surface charge, and hydrophilicity, respectively. Filtration studies such as pure water permeability, fouling resistance, and heavy metal rejection (arsenic) were performed at a 2 bar pressure. It was found that as the concentration of FHNTs increased in the membrane, the pure water flux also increased, indicating an increase in hydrophilicity. The membrane PPD-4, with the highest percentage of FHNTs, showed the maximum heavy metal removal. It was confirmed by the values of arsenic removal by the membranes containing FHNTs at 0 wt%, 0.2 wt%, 0.6 wt%, and 1 wt% that were found to be 24.80%, 33.18%, 35.54%, and 39.65%, respectively. © 2024 Advances in Environmental Technology (AET).
Porphyrin-azoheteroarenes: synthesis, photophysical, and computational studies
(Royal Society of Chemistry, 2025) Shet, S.N.; Bhat, V.G.; Swathi, S.G.; Udayakumar, U.; Shetti, V.S.
Azobenzenes (Ph-N = N-Ph) are well-known photochromic compounds with widespread applications. Replacing one or both phenyl rings of azobenzenes with heteroarenes leads to a new class of compounds known as azoheteroarenes (Het-N N-Ph/Het). Azoheteroarenes have gained attention as promising alternatives to traditional azobenzenes in the field of photopharmacology due to their ability to undergo photoswitching under visible light. Interestingly, the chemistry of porphyrin-containing azoheteroarenes has been underexplored. In this study, we present the synthesis of hitherto unknown hybrid molecules: porphyrin-azopyrroles (porphyrin-N N-pyrrole) and porphyrin-azoindoles (porphyrin-N N-indole), which also feature porphyrins with five-membered meso-substituents, such as 2-furyl and 2-thienyl groups. The porphyrin-azoheteroarenes with meso-tris(2-furyl/2-thienyl) substitutions demonstrate red-shifted absorption and emission bands, more significant Stokes shifts, and smaller optical bandgaps compared to hybrids containing only meso-aryl groups. Additionally, these porphyrin-azoheteroarenes exhibit higher fluorescence emission intensities than their corresponding precursor porphyrins. © 2025 The Royal Society of Chemistry.
Synthesis, Optoelectronic, and Photoelectrochemical Properties of an Azulene-Bridged Porphyrin Dimer
(American Chemical Society, 2025) Shet, S.N.; Murthy, D.H.K.; Chandrappa, S.; Galbao, S.J.; Patil, M.; Shetti, V.S.
Although azulene-incorporated porphyrin analogues, referred to as ?azuliporphyrins”, are well documented in the literature, the studies available on covalently tethered azulene–porphyrin hybrid molecules are limited. This work reports the synthesis of 1,3-azulene-bridged porphyrin dimers 3 and 4, achieved through the Suzuki–Miyaura cross-coupling reaction. The optoelectronic properties, photophysical behavior, excited-state dynamics, and potential application of dimer 4 in photoelectrochemical water splitting (PEC-WS) are investigated. Dimer 4 exhibits a smaller HOMO–LUMO gap and a lower ionization potential than the corresponding monomer 5. However, despite having an extended ?-conjugation, the V-shaped geometry of the dimer restricts its long-range aggregation and charge/exciton delocalization in comparison to its corresponding monomer. The computational electronic structure analysis complements the experimental findings. The results presented in this paper provide rational insights into the structure–property correlation within the less explored azulene–porphyrin hybrid systems. © 2025 The Authors. Published by American Chemical Society
Synthesis, Photophysical, and Computational Studies of Mono-Azo-Bridged, Meso-Tris(2-Furyl/2-Thienyl) Substituted Porphyrin-Arene Hybrids
(John Wiley and Sons Inc, 2024) Nagesh Shet, S.; Ganesh Bhat, V.; Hegde, V.; Hegde, G.; Udayakumar, U.; Shetti, V.S.
Porphyrins hybrids have been used as models to study various energy/electron transfer processes. The linkers connecting various subunits in such hybrids are vital in establishing good electronic communication between the subunits and the azo-bridge can be one of the efficient linkers to do so. Despite of these, the mono azo-bridged porphyrin-arene hybrids reported in the literature are only handful and the methods used to create them are not that efficient. In addition, the porphyrins used in this field so far contains only six-membered meso-substituents. By keeping these points in mind, we have developed a mild, one-pot, work-up-free, high-yielding method to synthesize mono-azo-bridged, porphyrin-arene hybrids which also features porphyrins containing three five-membered substituents like 2-furyl or 2-thienyl on their meso-positions. Along with the NMR and mass characterizations, the photophysical and computational studies of all the reported hybrids are presented. The hybrids containing meso-tris(2-furyl/thienyl) substituted porphyrins displayed red-shifted absorption and emission bands compared to their all-meso-aryl-containing counterparts. In general, all the hybrids displayed enhanced fluorescence quantum yields compared to their precursor porphyrins. Among the series, the meso-tris(2-furyl) substituted porphyrin-arene hybrids exhibited the more significant Stokes shift and small bandgap. The computational studies were in good agreement with the experimental findings. © 2024 Wiley-VCH GmbH.