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The idea of applying ultrasound (US) as a green activation method in chemical transformations, especially in catalytic alcohol oxidations, technically and ecologically appeals to chemists. In the present work, as an attempt to fulfill the idea of designing an eco-friendly system to oxidize alcoholic substrates into corresponding aldehydes, we devel...
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... Over the last decade, CQDs have become popular due to their small size, low toxicity, steady chemical inertness, stable fluorescence, and high quantum yield [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] . These properties make CQDs ideal for sensitive sensing applications [43][44][45] . ...
Excessive Cu²⁺ intake can cause neurological disorders (e.g. Wilson’s disease) and adversely affect the gastrointestinal, liver, and kidney organs. The presence of Cu²⁺ is strongly linked to the emergence and progression of Wilson's disease (WD), and accurately measuring the amount of copper is a crucial step in diagnosing WD at an early stage in a clinical setting. In this work, CQDs were fabricated through a facile technique as a novel fluorescence-based sensing platform for detecting Cu(II) in aqueous solutions, and in the serum samples of healthy and affected individuals by WD. The CQDs interact with Cu(II) ions to produce Turn-on and Turn-off states at nano-molar and micro-molar levels, respectively, with LODs of 0.001 µM and 1 µM. In fact, the Cu²⁺ ions can act like a bridge between two CQDs by which the charge and electron transfer between the CQDs may increase, possibly can have significant effects on the spectroscopic features of the CQDs. To the best of our knowledge, this is the first reported research that can detect Cu(II) at low levels using two different complexation states, with promising results in testing serum. The potential of the sensor to detect Cu(II) was tested on serum samples from healthy and affected individuals by WD, and compared to results obtained by ICP-OES. Astonishingly, the results showed an excellent correlation between the measured Cu(II) levels using the proposed technique and ICP-OES, indicating the high potential of the fluorimetric CQD-based probe for Cu(II) detection. The accuracy, sensitivity, selectivity, high precision, accuracy, and applicability of the probe toward Cu(II) ions make it a potential diagnostic tool for Wilson's disease in a clinical setting.
... This process induces periodic impaction expansion, forming micro-cavities or vapor-filled bubbles with substantial growth potential. The extreme conditions within these bubbles, containing trapped energy, lead to explosive bubble collapse, releasing exceptional heat and pressure into the liquid, surpassing 5000 K and 1000 bar [25,26]. Figure 1a shows an illustrative scheme of the porous synthesis of carbonaceous materials. ...
Selective oxidation, which is crucial in diverse chemical industries, transforms harmful chemicals into valuable compounds. Heterogeneous sonocatalysis, an emerging sustainable approach, urges in-depth exploration. In this work, we investigated N-doped or non-doped carbonaceous materials as alternatives to scarce, economically sensitive metal-based catalysts. Having synthesized diverse carbons using a hard-template technique, we subjected them to sonication at frequencies of 22, 100, 500, and 800 kHz with a 50% amplitude. Sonochemical reaction catalytic tests considerably increased the catalytic activity of C-meso (non-doped mesoporous carbon material). The scavenger test showed a radical formation when this catalyst was used. N-doped carbons did not show adequate and consistent sonoactivity for the selective oxidation of 4-Hydroxy-3,5 dimethoxybenzyl alcohol in comparison with control conditions without sonication, which might be associated with an acid–base interaction between the catalysts and the substrate and sonoactivity prohibition by piridinic nitrogen in N-doped catalysts.
... Finally, the resulting solution was solidified through freeze drying. [42][43][44] Fluorescent assay to explore the interaction between amino acids and drugs with chiral L/D-Trp-CQDs A quartz cuvette was utilized to hold a 2 mL solution of chiral L/ D-Trp-CQDs at a concentration of 200 ng mL À1 . A chiral analyte solution with a concentration of 300 nM was prepared in PBS (pH 7.4). ...
... The bending bands of the alkyl groups and CQC bonds are observed around 744 cm À1 . [42][43][44] In summary, the L/D-Try-CQD spectrum demonstrates the anticipated absorption bands, indicating the successful synthesis of this material. ...
... The peaks in the range of 111.0-137.1 ppm could be assigned to aromatic carbons, while the carbonyl group signals emerged at 180.3-183.1 ppm (Fig. 3B). [42][43][44] TEM, which is the most sophisticated imaging technique, uncovered the graphitic nature of the carbon building blocks with high crystallinity. Additionally, the spacing of parallel crystal planes was determined to be 0.21 nm, which is in good accordance with the (002) diffraction plane of the sp 2 carbon network. ...
Chiral detection plays a crucial role in drug development by ensuring the purity and efficacy of drugs. This enables researchers to accurately identify and quantify chiral molecules, thereby determining the active form of a drug and avoiding the potential side effects associated with the inactive form. Chiral carbon quantum dots (CQDs) have garnered attention in the field of biomaterials science due to their distinctive chiroptical and electronic properties, as well as their biocompatibility, ease of synthesis, excellent photostability, and convenient surface functionalization. In this study, we successfully synthesized chiral probes using a one-pot chemical synthesis process. Specifically, we synthesized chiral CQDs via one-step hydrothermal synthesis of l/d-tryptophan and citric acid. Comprehensive characterization techniques, including FT-IR, PL, UV-vis, XRD, circular dichroism, ¹H and ¹³C NMR, FESEM, AFM, TEM, and HRTEM, were employed to characterize the chiral CQDs. Notably, to the best of our knowledge, this study represents the first instance of well-defined chiral CQDs acting as probes for the chiral detection of l-DOPA. We evaluated the PL responses of the chiral CQDs to various chiral analytes such as cysteine, tryptophan, lysine, arginine, proline, histidine, d-penicillamine, l-DOPA, and captopril. The results demonstrate a strong interaction between the chiral l/d-Trp-CQDs and l-DOPA. Interestingly, the fluorescence spectrum of the l-Trp-CQDs remained unchanged upon the addition of l-DOPA. In contrast, d-Trp-CQDs exhibited a distinct response. When l-DOPA was introduced into the d-Trp-CQD solution, a new shoulder gradually emerged at 418 nm. This indicates that the d-Trp-CQDs exhibited a linear response (R² = 0.99) within the concentration range of 37–4000 nM of l-DOPA. Also, the limit of quantification (LOQ) and limit of detection (LOD) were calculated to be 37 and 11.2 nM, respectively. Therefore, chiral CQDs hold significant promise for enantioselective detection in the pharmaceutical industry and in other related fields. It offers a valuable means to ensure the safety and efficacy of pharmaceutical products.
... ppm, respectively ( Figure 2D). 11 TEM was used to examine the morphology and size distribution of the prepared CQDs. As shown in Figure 3A, the functionalized PHC exhibited a spherical shape with aggregation and a smooth surface. ...
... Due to these characteristic properties, CQDs are wid utilized in photovoltaic devices, medical diagnosis, sensing, drug delivery, catalys photocatalysis, optronic devices, bio-imaging, laser, single electron transistors, solar ce and LEDs [18][19][20][21][22][23][24][25][26][27][28][29]. However, very few reports have been investigated regarding t application of CQDs as a catalyst in photochemical water splitting [30] the preparation substituted 4H pyran with indole moieties [31], azide-alkyne cycloadditions [32], t degradation of levofloxacin [33], the selective oxidation of alcohols to aldehydes [34], t removal of Rhodamine B [35], the selective oxidation of amines and imine [3 high-efficiency cyclohexane oxidation [37], H-bond catalysis in Aldol condensations [3 intrinsic peroxidase-mimetic enzyme activity [39], and the ring opening of epoxides [4 In this review paper, we explain the synthetic approach, structure, optical properties, a applications of CQDs as a catalyst. Finally, we also discuss their future prospects. ...
... This is able to diffuse into the organic alcoholic phase and trigger the oxidation reaction with the assistance of an ultrasound wave. Finally, aldehyde was fabricated after inserting the alcoholic ligand on A-CQDs/W, followed by a ligand exchange reaction [34,151,152]. ...
Carbon quantum dots (CQDs), also known as carbon dots (CDs), are novel zero-dimensional fluorescent carbon-based nanomaterials. CQDs have attracted enormous attention around the world because of their excellent optical properties as well as water solubility, biocompatibility, low toxicity, eco-friendliness, and simple synthesis routes. CQDs have numerous applications in bioimaging, biosensing, chemical sensing, nanomedicine, solar cells, drug delivery, and light-emitting diodes. In this review paper, the structure of CQDs, their physical and chemical properties, their synthesis approach, and their application as a catalyst in the synthesis of multisubstituted 4H pyran, in azide-alkyne cycloadditions, in the degradation of levofloxacin, in the selective oxidation of alcohols to aldehydes, in the removal of Rhodamine B, as H-bond catalysis in Aldol condensations, in cyclohexane oxidation, in intrinsic peroxidase-mimetic enzyme activity, in the selective oxidation of amines and alcohols, and in the ring opening of epoxides are discussed. Finally, we also discuss the future challenges in this research field. We hope this review paper will open a new channel for the application of CQDs as a catalyst in organic synthesis.
Over the past decade, CdS QDs have become versatile semiconductors. Surface modification of CdS QDs has become an interesting case study, as it can eliminate surface defects and improve their photochemical properties. In this study, we report a new strategy of using carbon quantum dots containing a large number of thiol groups (CQDs-SH) as a passivating agent for the stabilization of CdS quantum dots (QDs). Various characterization techniques have clearly revealed that the CdS QDs have been successfully passivated by CQDs-SH. The photocatalytic performance of CQDs-SH/CdS QDs was investigated for the degradation of the insecticide imidacloprid from an aqueous solution. Parameters affecting the photodegradation process, including the light source, photocatalyst amount, initial concentration of the pollutant, radiation time, pH, oxidizing agent, and temperature, were investigated. Furthermore, the HPLC technique was applied to quantitatively analyze imidacloprid and its degradation products. The results of the HPLC analysis revealed that under simulated visible light at pH 9, imidacloprid scarcely existed after 90 min of irradiation (90.13% degradation). The LC–MS method was also used to detect the degradation products and investigate the mechanism of photodegradation of the pesticide. The results showed that the CQDs-SH/CdS QDs composite was a promising photocatalyst for the degradation of imidacloprid in wastewater.
This study presents a novel class of pseudohomogeneous catalysts (PHC) based on carbon quantum dots functionalized with terpyridine ligands (CQDs-Tpy) to immobilize and stabilize palladium nanoparticles (Pd NPs). Extensive characterization techniques clearly confirmed the successful stabilization of Pd NPs on CQDs-Tpy. The effectiveness of the catalyst was demonstrated in the selective aerobic oxidation of primary and secondary of benzylic alcohols to aldehydes in the absence of additives and phase transfer catalyst (PTC). Remarkably, the reactions predominantly yielded aldehydes without further oxidation to carboxylic acids. By employing low catalyst loadings (0.13 mol%), high conversions (up to 89%) and excellent selectivity (> 99%) of the aldehyde derivatives were achieved. Moreover, the CQDs-Tpy/Pd NPs catalyst displayed suitable catalytic activity and recyclability, offering potential economic advantages. This promising approach opens up new opportunities in the field of catalysis for designing subnanometric metal-based PHCs.
