Browsing by Author "Tae Wu Kim"

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Chitosan-based fluorescein isothiocyanate film as a highly efficient metal-free photocatalyst for solar-light-mediated direct C-H arylation
(John Wiley and Sons Ltd, 2021) Pooja Singh; Rajesh K. Yadav; Tae Wu Kim; Abhishek Kumar; D.K. Dwivedi
Development of ecofriendly and low-cost highly efficient photocatalysis is of importance in the field of chemical synthesis. Currently, various metals-based organic materials, metal oxide nanoparticles, and metal nanomaterials have been urbanized as light harvesting photocatalysts for direct carbon (C)-hydrogen (H) arylation of aryl diazonium salts and heteroarenes. These light harvesting photocatalysts, however, still suffer from poor stability, reusability problem, high cost, or less selectivity. Herein, we report the fabrication of a novel chitosan-based fluorescein isothiocyanate (CBFITC) film photocatalyst and demonstrate its tremendous photocatalytic activity, high yields (97 ± 0.015%), selectivity (99%), and reusability to catalyze the metal free solar-light-mediated direct CH arylation of aryl diazonium salts and heteroarenes at ambient temperature. Moreover, CBFITC film photocatalyst can be recycled more than five times without loss of activity, verifying this photocatalyst excellent light harvesting ability and stability. The present approach to fabricate a metal-free film photocatalyst with the suitable band gap will be a new platform for efficient photocatalytic reaction and provide a new insight into the solar chemical synthesis. © 2020 John Wiley & Sons Ltd
Fabrication of Graphitic Carbon Nitride-Based Film: An Emerged Highly Efficient Catalyst for Direct C—H Arylation under Solar Light
(Shanghai Institute of Organic Chemistry, 2021) Surabhi Chaubey; Rajesh K. Yadav; Tae Wu Kim; Tara Chand Yadav; Abhishek Kumar; D.K. Dwivedi; B.K. Pandey; Atul P. Singh
Photoredox C—H bond formation can proceed in aerobic environment under solar light and has therefore become attractive. Nowadays, different types of expensive novel metal complexes and nanomaterials have been urbanized as photocatalysts for direct C—H bond formation in between derivatives of heteroarenes (HAs) and aryl diazonium salts. These photocatalysts, however, still suffer from poor stability, high cost, and decay. Herein, a graphitic carbon nitride-based fluorescein isothiocyanate (g-C3N4–FITC) film photocatalyst has been reported, which shows excellent light harvesting ability, and band gap suitability to catalyze the metal free direct C—H arylation of HAs under solar light at ambient temperature. Moreover, the g-C3N4–FITC film photocatalyst can be reused four times without significant loss of activity, confirming the excellent photocatalytic stability. The current strategy to construct a g-C3N4–FITC film photocatalyst for direct C—H arylation opens a new path towards replacing metal-based catalysts in fine chemical synthesis. © 2021 SIOC, CAS, Shanghai and Wiley-VCH GmbH
Generation and Regeneration of the C(sp3)-F Bond and 1,4-NADH/NADPH via Newly Designed S-gC3N4@Fe2O3/LC Photocatalysts under Solar Light
(American Chemical Society, 2022) Satyam Singh; Rajesh K. Yadav; Tae Wu Kim; Chandani Singh; Pooja Singh; Surabhi Chaubey; Atul. P. Singh; Jin-Ook Baeg; Sarvesh K. Gupta; Dhanesh Tiwary
Due to the pharmaceutical, biological, physical, and chemical properties of fluorinated compounds and 1,4-NADH/NADPH, these species have attracted a lot of attention from researchers across the chemical society. Despite their crucial significance, present methods of regenerating cofactors (1,4-NADH/NADPH) as well as inserting fluorine into organic compounds suffer from ruthless drawbacks. Herein, we designed a highly efficient S-gC3N4@Fe2O3/LC photocatalyst, and its in situ generations were accomplished by calcinations of Fe2O3, melamine (M), thiophenol (T), and lignin carbon (LC). The Fe2O3part performs similar to an additional light harvester, gifting utmost photo-generated electrons, whereas the carbon part bridges a "thoroughfare" to make easy electron transfer from Fe2O3to S-gC3N4(Schemes 1 and 2). Therefore, the newly designed S-gC3N4@Fe2O3/LC photocatalyst is more efficient for the generation and regeneration of the C(sp3)-F bond and 1,4-NADH/NADPH due to its surface active sites and defects. © 2022 American Chemical Society. All rights reserved.
Revolutionizing regeneration of NADH and deoxygenation of sulfide: Harnessing visible light with SDG@TPP composites for powerful synthetic applications
(Elsevier Ltd, 2023) Lovely Kumari; Satyam Singh; Rajesh K. Yadav; Rehana Shahin; Tae Wu Kim; Suresh K. Pandey; Dhanesh Tiwari; Alok Kumar Singh; Satyanath; D.K. Dwivedi; Navneet Kumar Gupta
Aqueous ascorbic acid splitting through photocatalysis is a potential method for turning solar energy into value-added compounds. As a result, converting solar light into green solar fine chemicals in an ecologically responsible and cost-effective manner remains a difficult issue. The solvothermal approach was used to effectively construct an SDG@TPP composite photocatalyst.To that end, we present here the synthesis and development of a sulfur-doped graphene (SDG)-based visible light active composite photocatalyst (SDG@TPP), in which SDG interacts with TPP (tetraphenyl porphyrin) through - stacking. Due to its high molar extinction coefficient and delayed recombination features, the newly manufactured SDG@TPP photocatalyst acts in a highly effective way, resulting in higher NADH regeneration (66.1 %) and sulfoxide deoxygenation than SDG photocatalyst. More importantly, a little quantity of TPP on the surface of SDG can efficiently stimulate photoelectron injection and improved photocatalytic activity. This research should shed light on how to create metal-free SDG@TPP composites with good solar energy conversion. © 2023
Transformation of PMMA from sunlight-blocking to sunlight-activated coupled with DNH photocatalytic platform for oxidative coupling of amines and generation/regeneration of LDC/NADH
(John Wiley and Sons Inc, 2024) Satyam Singh; Rajesh K. Yadav; Ahmad Umar; Ahmed A. Ibrahim; Tae Wu Kim; Atul Pratap Singh; Rajesh Kumar; Sandeep Chaudhary; Dilip K. Dwivedi; Ravindra Vikram Singh; Navneet Kumar Gupta; Chandani Singh; Jin-O. Baeg; Sotirios Baskoutas
The photocatalytic oxidation and generation/regeneration of amines to imines and leucodopaminechrome (LDC)/NADH are subjects of intense interest in contemporary research. Imines serve as crucial intermediates for the synthesis of solar fuels, fine chemicals, agricultural chemicals, and pharmaceuticals. While significant progress has been made in developing efficient processes for the oxidation and generation/regeneration of secondary amines, the oxidation of primary amines has received comparatively less attention until recently. This discrepancy can be attributed to the high reactivity of imines generated from primary amines, which are prone to dehydrogenation into nitriles. In this study, we present the synthesis and characterization of a novel polymer-based photocatalyst, denoted as PMMA-DNH, designed for solar light-harvesting applications. PMMA-DNH incorporates the light-harvesting molecule dinitrophenyl hydrazine (DNH) at varying concentrations (5%, 10%, 20%, 30%, and 40%). Leveraging its high molar extinction coefficient and slow charge recombination, the 30% DNH-incorporated PMMA photocatalyst proves to be particularly efficient. This photocatalytic system demonstrates exceptional yields (96.5%) in imine production and high generation/regeneration rates for LDC/NADH (65.27%/78.77%). The research presented herein emphasizes the development and application of a newly engineered polymer-based photocatalyst, which holds significant promise for direct solar-assisted chemical synthesis in diverse commercial applications. © 2023 American Society for Photobiology.