CuIn-ethylxanthate, a “Versatile Precursor” for Photosensitization of Graphene-Quantum Dots and Nanocatalyzed Synthesis of Imidazopyridines with Ideal Green Chemistry Metrics

Abstract

Recently, the development of hybrid nanocatalysts involving Earth-abundant transition metals for photosensitization and multicomponent reactions in industry and academia has been a matter of intense study. Such hybridized catalytic systems minimize the production cost and act as a bridged system by diversifying the application in different areas. In the present study, copper indium ethylxanthate was used as a versatile precursor for the synthesis of colloidal chalcopyrite phase copper indium sulfide nanoparticles (C-CIS NPs) in photosensitization of graphene quantum dots and reusable powdered wurzite phased copper indium sulfide nanoparticles (PW-CIS500 NPs) for selective and efficient single-pot sustainable synthesis of substituted imidazopyridines via an A3 coupling strategy of an aldehyde, amine, and alkyne. The material was characterized by various spectroscopic techniques viz. high-resolution transmission electron microscopy, powder X-ray diffraction, field emission scanning electron microscopy, elemental mapping studies, UV visible spectroscopy, photoluminescence, Xray photoelectron spectroscopy, Brunauer−Emmett−Teller analysis, inductively coupled plasma optical emission spectroscopy/mass spectrometry, etc. Quenching of photoluminescence intensity of colloidal CuInS 2 on anchoring the graphene quantum dots (GQDs) was confirmed by photosensitization of GQDs via efficient charge transfer in the CIS-GQD interface. On the other hand, the PW-CIS500 nanocomposites (NCs) catalyzed A3 coupling strategy demonstrates the high catalytic efficiency for the A3 coupling reaction giving substituted imidazopyridines without losing its activity and could be recycled with a total turnover (TOF) number of >210, good E-factor of 0.13, and high RME of 88%.

Zinc Oxide Sensitized Graphene Quantum Dots “ZnO‐GQDs”: A Hybrid Concept to Study Charge Transfer and its Catalytic Applicability to Synthesize Tetrasubstituted Propargylamines

“…Inset of Figure 1 shows the typical UV spectra of GQDs [43,44] which we have already explained our previous report by showing the formation of luminescent GQDs [59] . The photoluminescence (PL) spectrum of the GQD at different excitation wavelength, depicts an excitation dependent pattern.…”

“…[20,42] Inset of Figure 1 shows the typical UV spectra of GQDs [43,44] which we have already explained our previous report by showing the formation of luminescent GQDs. [59] The photoluminescence (PL) spectrum of the GQD at different excitation wavelength, depicts an excitation dependent pattern. Moreover, a broad PL characteristic peak for carbon-based quantum dots appeared which shows a gradual red shift from 435 to nm with decrement in peak intensity when the excitation wavelength changed from 320 to 540 nm.…”

Sustainable Liquid-Phase Exfoliation of Layered Materials with Nontoxic Polarclean Solvent

“…The advent of two-dimensional (2D) materials had a ground-breaking impact on science and technology, − due to their peculiar properties with high application capabilities in different fields, such as energy storage, − catalysis, − optoelectronic devices, − and gas sensing. − A key point for the technological exploitation of 2D materials is represented by their large-scale production, which still remains challenging. − Actually, since the isolation of graphene, , fundamental studies on 2D materials were carried out mostly on micrometric flakes mechanically exfoliated from parental bulk crystals (top-down approach) or on ultrathin layers grown by chemical vapor deposition , (bottom-up approach). While mechanical exfoliation suffers from nonscalable processes with scarce reproducibility, chemical vapor deposition requires specific substrates enabling epitaxial growth, − with subsequent problems related to the etching of 2D sheets from the substrate resulting in flakes with degraded crystalline quality with a high amount of defects and metallic impurities and/or polymer residuals from the transfer process altering the physicochemical properties of transferred flakes of 2D materials .…”

Application of 2-Aminopyridines in the Synthesis of Five- and Six-Membered Azaheterocycles

“…以 2-氨基吡啶、芳香醛和 末端炔烃为底物, 一锅法得到芳香醛中芳环位于咪唑环 的 2-位而非 3-位的产物 [35] . 例如, Rawat 课题组 [36] 以 CuIn 2 掺杂的石墨烯量子点为催化剂, 三组分经历了生 成五元环的 5-exo-dig 分子内环化反应, 得到了 2,3-二芳 基取代咪唑并[1,2-a]吡啶(Scheme 6). 类似地, 含叁键的化合物如腈 [37] 或异腈 [38] , 亦能作 为 2-氨基吡啶 1、芳香醛 9 三组分反应体系的另一底物 发生成环反应.…”