Advances in Homogeneous Photocatalytic Organic Synthesis with Colloidal Quantum Dots

Wang, Danyan; Yin, Yu-Yun; Feng, Chuan-Wei; Rukhsana, .; Shen, Yong‐Miao

doi:10.3390/catal11020275

Cited by 16 publications

(10 citation statements)

References 51 publications

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“…110 In the majority of cases, cadmium chalcogenide nanocrystals, including core/shell ones, were used for this purpose. 111 The most important drawback of the above-mentioned photocatalysts is their toxicity. However, a few reports of the use of nontoxic nanocrystals, such as core− shell binary InP/ZnS, appeared in the literature.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In the last few years, several papers appeared devoted to the application of inorganic semiconductors nanocrystals as photocatalyst of many important reactions, mainly the reduction ones , and C–C coupling reactions . In the majority of cases, cadmium chalcogenide nanocrystals, including core/shell ones, were used for this purpose . The most important drawback of the above-mentioned photocatalysts is their toxicity.…”

Section: Resultsmentioning

confidence: 99%

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Indium(II) Chloride as a Precursor in the Synthesis of Ternary (Ag–In–S) and Quaternary (Ag–In–Zn–S) Nanocrystals

et al. 2022

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A new indium precursor, namely, indium(II) chloride, was tested as a precursor in the synthesis of ternary Ag−In−S and quaternary Ag−In−Zn−S nanocrystals. This new precursor, being in fact a dimer of Cl 2 In−InCl 2 chemical structure, is significantly more reactive than InCl 3 , typically used in the preparation of these types of nanocrystals. This was evidenced by carrying out comparative syntheses under the same reaction conditions using these two indium precursors in combination with the same silver (AgNO 3 ) and zinc (zinc stearate) precursors. In particular, the use of indium(II) chloride in combination with low concentrations of the zinc precursor yielded spherical-shaped (D = 3.7−6.2 nm) Ag−In−Zn−S nanocrystals, whereas for higher concentrations of this precursor, rodlike nanoparticles (L = 9−10 nm) were obtained. In all cases, the resulting nanocrystals were enriched in indium (In/Ag = 1.5−10.3). Enhanced indium precursor conversion and formation of anisotropic, longitudinal nanoparticles were closely related to the presence of thiocarboxylic acid type of ligands in the reaction mixture. These ligands were generated in situ and subsequently bound to surfacial In(III) cations in the growing nanocrystals. The use of the new precursor of enhanced reactivity facilitated precise tuning of the photoluminescence color of the resulting nanocrystals in the spectral range from ca. 730 to 530 nm with photoluminescence quantum yield (PLQY) varying from 20 to 40%. The fabricated Ag−In−S and Ag−In−Zn−S nanocrystals exhibited the longest, reported to date, photoluminescence lifetimes of ∼9.4 and ∼1.4 μs, respectively. It was also demonstrated for the first time that ternary (Ag−In− S) and quaternary (Ag−In−Zn−S) nanocrystals could be applied as efficient photocatalysts, active under visible light (green) illumination, in the reaction of aldehydes reduction to alcohols.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Indium(II) Chloride as a Precursor in the Synthesis of Ternary (Ag–In–S) and Quaternary (Ag–In–Zn–S) Nanocrystals

et al. 2022

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“…Semiconductor quantum dots (QDs) combine advantageous aspects of both homogeneous (high surface–volume ratio, solubility in reaction media, light penetration) and heterogeneous (durability, substrate binding) catalysts, and therefore offer new opportunities for photoredox catalysis. , QDs have proven to be robust fluorophores and photocatalysts, generally exhibiting superior photostability to small-molecule dyes; − however, applications of QDs to organic synthesis remain underexplored. To address the need for continued development of photoredox catalysts, our group and others have been interested in new applications of QDs in organic chemistry. ,− In addition to their high photostability, QDs exhibit tunable, size-dependent optical and redox properties; are made in single-step syntheses with no chromatography from abundant precursors; reversibly bind to many molecules at once (typically 1–5 ligands/nm 2 of QD surface are found for CdSe QDs − ) through common organic functional groups (−CO 2 H, −PO 3 H, −SH, −NH 2 ); can become charged with many electrons at once without decomposing; , and undergo many electronic processes with no direct analogue in small molecules …”

Section: Introductionmentioning

confidence: 99%

CdS Quantum Dots as Potent Photoreductants for Organic Chemistry Enabled by Auger Processes

et al. 2022

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Strong reducing agents (<−2.0 V vs saturated calomel electrode (SCE)) enable a wide array of useful organic chemistry, but suffer from a variety of limitations. Stoichiometric metallic reductants such as alkali metals and SmI 2 are commonly employed for these reactions; however, considerations including expense, ease of use, safety, and waste generation limit the practicality of these methods. Recent approaches utilizing energy from multiple photons or electron-primed photoredox catalysis have accessed reduction potentials equivalent to Li 0 and shown how this enables selective transformations of aryl chlorides via aryl radicals. However, in some cases, low stability of catalytic intermediates can limit turnover numbers. Herein, we report the ability of CdS nanocrystal quantum dots (QDs) to function as strong photoreductants and present evidence that a highly reducing electron is generated from two consecutive photoexcitations of CdS QDs with intermediate reductive quenching. Mechanistic experiments suggest that Auger recombination, a photophysical phenomenon known to occur in photoexcited anionic QDs, generates transient thermally excited electrons to enable the observed reductions. Using blue light-emitting diodes (LEDs) and sacrificial amine reductants, aryl chlorides and phosphate esters with reduction potentials up to −3.4 V vs SCE are photoreductively cleaved to afford hydrodefunctionalized or functionalized products. In contrast to small-molecule catalysts, QDs are stable under these conditions and turnover numbers up to 47 500 have been achieved. These conditions can also effect other challenging reductions, such as tosylate protecting group removal from amines, debenzylation of benzyl-protected alcohols, and reductive ring opening of cyclopropane carboxylic acid derivatives.

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“…[ 25–28 ] Up to now, many cost‐effective and environmental friendly visible‐light photocatalysts with good durability and high reactivity have been disclosed. [ 29–33 ] However, the logical design and fabrication of excellent visible‐light‐responsive photocatalysts are still a significant challenge in organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

Synergistic promotion of the photocatalytic efficacy of CuO nanoparticles by heteropolyacid‐attached melem: Robust photocatalytic efficacy and anticancer performance

Liu

Abbaspour

Rouki

et al. 2022

Applied Organom Chemis

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The in situ photocatalytic oxidation of aromatic alcohols to aldehydes by air under visible-light-driven condition is an attractive and beneficial route regarding environmental crises and worldwide energy economy. Herein, CuOmelem-heteropolyacid nanophotosensitizer is disclosed as an efficient heterostructured nanocomposite involving H 5-n PW 10 V 2 O 40 nÀ … (melem-NH 3 + ) n ionic liquid, successfully prepared via a facile and straightforward procedure.This nanocomposite is characterized employing routine techniques such as Xray diffraction (XRD), Fourier transform infrared (FT-IR), diffuse reflectance spectra (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM),and Brunauer-Emmett-Teller (BET). The resultant nanocomposite exhibited superior photocatalytic efficacy than its pristine melem, HPA, and CuO constituents in the in situ photo-oxidation of benzylic alcohols and in the fast condensation with o-phenylenediamine to generate a range of 2-substituted benzimidazoles, as important precursors in the synthesis of important pharmaceuticals under the illumination of a green laser light (λ 535 nm). This study suggests a radical pathway involving reactive species such as •O 2 À and OH• together with h + in a photocatalytic process. Stability and reusability experiments along with hot filtration test ensured sufficient reproducibility of the nanophotocatalyst in the reaction medium. At the final part of this study, the in vitro cellular cytotoxicity of CuO-melem-heteropolyacid nanohybrid material was evaluated on A549 human lung cancer cell line with the MTT assay.The distinct reduction in cell viability affirmed cytotoxicity of the nanomaterial against the performed cell line.

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Advances in Homogeneous Photocatalytic Organic Synthesis with Colloidal Quantum Dots

Cited by 16 publications

References 51 publications

Indium(II) Chloride as a Precursor in the Synthesis of Ternary (Ag–In–S) and Quaternary (Ag–In–Zn–S) Nanocrystals

Indium(II) Chloride as a Precursor in the Synthesis of Ternary (Ag–In–S) and Quaternary (Ag–In–Zn–S) Nanocrystals

CdS Quantum Dots as Potent Photoreductants for Organic Chemistry Enabled by Auger Processes

Synergistic promotion of the photocatalytic efficacy of CuO nanoparticles by heteropolyacid‐attached melem: Robust photocatalytic efficacy and anticancer performance

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