Browsing by Author "Anshuman"

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Fluorene and Triazine-Based Conjugated Polymer Networks with Tuned Frontier Orbital Energy Levels for Improving Organic Photocatalysis
(American Chemical Society, 2024) Raj Laxmi; Anshuman; Neelam Gupta; None Anamika; Arpita Maurya; Ravi Prakash Behere; Rahul Sharma; Biswajit Maiti; Biplab K. Kuila
Here, we describe a method for fine-tuning the frontier orbital energy levels or redox potential of a conjugated polymer network (CPN) consisting of triazine and fluorene by systematically introducing electron-withdrawing groups at the fluorene moiety through simple structural modification. The band gap of CPN decreases with an increase in the strength of the electron-withdrawing group, and the relative position of the frontier orbital energy becomes more favorable for reactions like photocatalytic aerobic oxidation, which has been further confirmed by theoretical and experimental studies. The CPN with a CN group at the 9 position of fluorene (CPN3) shows the maximum photocatalytic activity (32% higher) compared to CPN1 (hydrogen at the 9 position) in white light. The best-performing catalyst CPN3 was further employed for photocatalytic reactions under white light, like the oxidation of alcohols to carbonyl and boronic acid to the corresponding alcohol, which show noteworthy characteristics like low catalyst loading, high yield, and selectivity with broad substrate scope (aliphatic, aromatic, biphenyl, and heterocyclic). CPN3 exhibited turnover frequencies of 13.33 and 10.9 mmol g-1 h-1 in 3 W blue and white LED lights, respectively, which are much higher than those of state-of-art photocatalysts. The recyclability of the catalyst was tested for up to 5 cycles without much change in the catalytic activity. The practical usefulness of the suggested method was further demonstrated by the CPN3-photocatalyzed gram-scale synthesis of high-value chemicals such as acetophenone from 1-phenylethanol and phenol from phenylboronic acid. © 2024 American Chemical Society.
Visible light driven C-N cross-coupling reactions catalysed by a conjugated polymer network
(Royal Society of Chemistry, 2025) Anshuman; Raj Laxmi; Renu Mishra; Biplab Kumar Kuila
This work describes the use of a fluorine and triazine containing conjugated polymer network (CPN) susceptible to in situ Pd doping during its preparation for photocatalytic C-N cross-coupling reactions between aryl halides and amines under visible light irradiation at room temperature. Comprehensive mechanistic investigations were conducted in order to understand the role of each variable and reactive species involved in the reaction pathway. The broad substrate range (aliphatic, aromatic, and heterocyclic) with good functional group tolerance, recyclability, low catalyst loading (5.0 wt%), use of low intensity white LED light (0.05 W cm−2), high yields (95-82%), and high turnover frequency values of up to 1515.46 h−1 are some of the primary advantages of the described method. The CPN photocatalyzed gram-scale synthesis of high-value compounds like 4-(4-nitrophenyl)morpholine, 4-phenylmorpholone, and N-benzylpyridine-2-amine further illustrated the practical utility of the proposed approach. © 2025 The Royal Society of Chemistry.