Small
·
2024
·Vol. 20
·期 29
·2310563
·
IF 13
Pengfei Li,Shanshan Xue,Lu Sun,Xiaobao Ma,Wenning Liu,Li An,Yichang Liu,Dan Qu,Zaicheng Sun
Carbon dots (CDs) have received considerable attention in many application areas owing to their unique optical properties and potential applications; however, the fluorescent mechanism is an obstacle to their applications. Herein, three-color emissive CDs are prepared from single o -phenylenediamine (oPD) by regulating the ratio of ethanol and dimethylformamide (DMF). Fluorescent mechanism of these CDs is proposed as molecular state fluorescence. Reaction intermediates are identified using liquid chromatrography–mass spectroscopy (LC–MS) and 1 H nuclear magnetic resonance (NMR) spectra. 1H-Benzo[d]imidazole (BI), 2,3-diaminophenazine (DAP), and 5,14-dihydroquinoxalino[2,3-b] phenazine (DHQP) are proposed to be the fluorophores of blue, green, and red emissive CDs by comparing their optical properties. As per the LC–MS and 1 H-NMR analysis, DHQP with red emission tends to form from DAP and oPD in pure ethanol. By adding DMF, BI formation is enhanced and DHQP formation is suppressed. The prepared CDs exhibit green emission with DAP. When the DMF amount is >50%, BI formation is considerably promoted, resulting in DAP formation being suppressed. BI with blue emission then turns into the fluorophore of CDs. This result provides us an improved understanding of the fluorescent mechanism of oPD-based CDs, which guides us in designing the structure and optical properties of CDs.
研究领域:
材料科学
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光学
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化学
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产品关联
DOI
PubMed
高影响因子
Light-Science & Applications
·
2022
·Vol. 11
·期 1
·1-11
·
IF 20.257
Li Pengfei,Xue Shanshan,Sun Lu,Zong Xupeng,An Li,Qu Dan,Wang Xiayan,Sun Zaicheng
Carbon dots (CDs) as the advancing fluorescent carbon nanomaterial have superior potential and prospective. However, the ambiguous photoluminescence (PL) mechanism and intricate structure-function relationship become the greatest hindrances in the development and applications of CDs. Herein, red emissive CDs were synthesized in high yield from o -phenylenediamine (oPD) and catechol (CAT). The PL mechanism of the CDs is considered as the molecular state fluorophores because 5,14-dihydroquinoxalino[2,3-b] phenazine (DHQP) is separated and exhibits the same PL properties and behavior as the CDs. These include the peak position and shape of the PL emission and PL excitation and the emission dependence on pH and solvent polarity. Both of them display close PL lifetime decays. Based on these, we deduce that DHQP is the fluorophore of the red emissive CDs and the PL mechanism of CDs is similar to DHQP. During the PL emission of CDs, the electron of the molecule state can transfer to CDs. The formation process of DHQP is further confirmed by the reaction intermediates (phthalazine, dimers) and oPD. These findings provide insights into the PL mechanism of this type of CDs and may guide the further development of tunable CDs for tailored properties.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2025
·
IF 3.9
Jianglong Deng,Lintao Chen,Hao Chen,Jiazhuang Guo,Cai-Feng Wang,Su Chen
Carbon dots (CDs) have attracted increasing attention due to their remarkable optical characteristics and broad application prospects. Here, we report an efficient and mild strategy for the rapid preparation of green-emissive CDs (G-CDs) via a microwave-assisted approach. The G-CDs were synthesized via microwave-assisted thermal treatment of m-phenylenediamine (m-PD) and phthalic acid in ethylene glycol for 10 min, followed by purification. The resultant G-CDs exhibit a bright green photoluminescence (PL) centered at 515 nm with an absolute quantum yield (QY) of 66.5%. Structural characterization revealed that the G-CDs possess a highly graphitized carbon core and are enriched with various surface functional groups. Mechanistic studies on fluorescence indicated that the green emission of G-CDs originates from the interaction between the surface-attached green fluorophore, phenazine-2,7-diamine (2,7-DAP), and the graphitized carbon core. In addition, the prepared G-CDs/polyvinylpyrrolidone (G-CDs/PVP) composite film exhibits excellent optical properties and was successfully applied in the fabrication of green light-emitting diodes (LEDs). This study might promote the understanding of the fluorescence mechanism and the development of preparation methods for high-performance G-CDs based on m-PD.
研究领域:
材料科学
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光学
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产品关联
DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2023
·
IF 11.4
Tian-xiang Li,De-fang Zhao,Lin Li,Yang Meng,Yu-hui Xie,Dong Feng,Feng Wu,Delong Xie,Yuxin Liu,Yi Mei
The complexity of biomass components leads to significant variations in the performance of biomass-based carbon dots (CDs). To shed light on this matter, this study presents a comparative analysis of the fluorescence properties of CDs using pure cellulose, lignin, and protein as models. Three CDs showed different fluorescent properties, resulting from the structure difference and carbonization behavior in the hydrothermal. The relatively gentle thermal degradation of proteins allows the macromolecular structure of amino acids to be preserved. This preservation results in a more regular lattice structure, a larger sp 2 domain size, and N-doping, which contribute to the highest quantum yield (QY) of 8.7% of the CDs. In contrast, cellulose undergoes more severe thermal degradation with large amounts of small molecules generated, resulting in the CDs with fewer surface defects, more irregular lattice structures, and lower QY. These results provide a guideline for the design of carbon dots from different biomass.
研究领域:
材料科学
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化学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 53
·期 9
·6459-6470
·
IF 2.993
Feng Zhibiao,Li Zeliang,Zhang Xingwei,Xu Guoqiang,Zhou Nan
Herein, we report the synthesis of carbon dots (CDs) with two characterized absorption bands but without excitation wavelength-dependent fluorescence via a one-step hydrothermal method. The structure of CDs was characterized using X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared, and UV–Vis spectroscopy. The structure and photoluminescence of CDs vary significantly with different raw materials and preparation methods, and the mechanism of luminescence is not clear yet. Hence, we studied the luminescence mechanism behind two characterized absorption bands of CDs using fluorescence quenching method with ninhydrin and several ions as quenchers. The influence of the surface groups of CDs on its photoluminescence properties was also discussed. Ninhydrin and a variety of other ions exhibited different quenching effects on the fluorescence emissions which obtained at the two absorption bands of CDs. Combining with the structure characterization results, it can be concluded that the emission wavelength is mainly determined by the carbon core, while the excitation wavelength is determined by the surface nitrogen-containing groups. (The excitation at 234 nm might be due to the Schiff base structure, while the excitation at 345 nm was mainly due to the amide structure.) Furthermore, based on the interaction of NO 2 − with the surface nitrogen-containing groups of CDs, a quantitative detection method of NO 2 − using CDs was proposed in our study. CDs exhibited high selectivity for NO 2 − at pH 1.6 with good linearity to NO 2 − concentration in the range of 1–10 μM.
研究领域:
材料科学
·
分析化学
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DOI
高影响因子
Analytical Methods
·
2022
·Vol. 15
·期 3
·353-360
·
IF 3.532
Qingchun Huang,Hongcan Sun,Changgui Lu,Chunlei Wang,Shuhong Xu
Exploring the origin of emission is fundamental in the field of carbon dots (CDs). Due to the lack of suitable in situ probing techniques, it is necessary to explore effective alternative methods that can accurately reflect the relationship between the emission and the composition of the functional groups of CDs. Herein, we propose a new method of post-synthetic treatment of CDs by photo-oxidation to investigate the origin of emission for CDs. After the addition of a photo-oxidant into pre-prepared CDs under UV irradiation, the fluorescence of CDs can be regulated from the original orange emission to the final green emission due to the damage of original functional groups and the formation of new functional groups on CDs during the post-treatment process. The abundant dynamic information about the functional groups and emissions of CDs during the visible and ready-to-monitor post-treatment process makes it possible to quantitatively analyze the origin of the emission of CDs. Our results suggest that the emission sub-peaks at 560 nm and 600 nm relate to the CD surface-state-associated –NH3+ groups, while the emission sub-peak at 537 nm or 494 nm is associated with the CD surface-state-associated –OH groups or the CD surface-state-associated carbonyl groups (CO). Under UV irradiation, the CD surface-state-associated –NH3+ groups can be continuously converted into the CD surface-state-associated –OH groups and the CD surface-state-associated carbonyl groups (CO), leading to the changed emission color of CDs.
研究领域:
材料科学
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化学
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产品关联
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Yongyu Li,Jianjun Chen,Yaping Wang,Huiji Li,Jihong Yin,Mengyan Li,Ling Wang,Haijie Sun,Lingxia Chen
A one-step direct pyrolysis method without any post-treatment steps and a mass yield of up to 69% was realized for preparing N-doped carbon dots (NCDs). The NCDs exhibit excellent excitation-independent blue fluorescence with quantum yield (QY) of 65.5%, and their luminescence mechanism was explored based on optical properties and structural composition, which mainly originates from surface state photoluminescence (PL). The NCDs display highly selective and sensitive detection of Fe 3+ in tris-HCl buffer system, a good linear relationship between PL intensity ratios and Fe 3+ concentrations was obtained in concentration range of 0 to 400 μM with a low LOD of 0.703 μM. The formation of ferric hydroxide colloid is the main reason for the specific recognition of Fe 3+ by NCDs, and buffer solution plays a key role in the formation of ferric hydroxide colloid and selective detection of Fe 3+ . The sensing mechanism is a dynamic quenching electron transfer process in the action of hydrogen bonding and colloidal adsorption. Three real water samples were applied to evaluate actual application of NCDs probe, satisfactory recoveries (93.5%–105.6%) indicate that NCDs has great practical potential for detection of metal ions in environmental water assays.
研究领域:
材料科学
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分析化学
·
环境科学
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2025
·
IF 2.5
Shuai Lan,ChenSa Zhang,YuLin Li,Sibo Shen,Dongjun Wang,Kui Niu
In order to mimic the emissive mechanism of green fluorescent protein (GFP) by using chemical reagents, we systematically explored the micelle-triggered fluorescent system formed by non-conjugated simple amine molecules and cyclopentanol (CPA). In comparison with its amphiphilic ring-type homologues and linear homologues, we found that the fluorescent properties of the prepared systems were highly sensitive to surrounding environment. The present works help us get deeper cognition on the abnormal fluorescence mechanism, and provide a novel way to design highly efficient luminescent systems via green, facile and low-cost procedures, which was fundamentally different from the traditional method. Simultaneously, fluorescent micelles exhibit specific quenching of Fe3+, which can be combined with chestnut lignin to prepare Fe3+ detection and adsorption materials.
研究领域:
生物化学
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材料科学
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环境科学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2014
·
IF 2.538
Yanling Hao,Zhixing Gan,Jiaqing Xu,Xinglong Wu,Paul K. Chu
Although carbon quantum dots (CQDs) possess excellent luminescence properties, it is a challenge to apply water-soluble CQDs to tunable luminescent devices. Herein, quaternary CQDs are incorporated into poly(ethylene glycol) to produce poly(ethylene glycol)/CQD composite solid films which exhibit strong and tunable blue–red emission. The fluorescent quantum yield reaches 12.6% which is comparable to that of many liquid CQDs and the photoluminescence characteristics are determined to elucidate the fluorescence mechanism. The CQD solid films with tunable optical properties bode well for photoelectric devices especially displays.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
DYES AND PIGMENTS
·
2020
·
IF 4.613
Xiufen Liao,Congjin Chen,Ruxia Zhou,Quanlong Huang,Qinglong Liang,Zuqiang Huang,Yanjuan Zhang,Huayu Hu,Yanglin Liang
In this study, N-doped carbon dots (N-CDs) synthesized from the main components of plants, including cellulose (N-cCDs), lignin (N-lCDs), and xylose (N-xCDs), were compared. TEM, XRD , FT-IR, and XPS were carried out to characterize their morphology and chemical composition. Results show that the three obtained N-CDs contained N-doped sp 2 and sp 3 hybrid carbon core, which was surrounded by oxygen- and nitrogen-containing functional groups. The three N-CDs exhibited a novel double excitation-one emission phenomenon, and their fluorescence were significantly enhanced by N-doping. Moreover, this study indicated that high lignin-containing biomass is not appropriate for producing CDs by hydrothermal method . Cellulose is conducive to produce CDs, while it needs a relatively high temperature and a long time. Low-molecular carbohydrate-rich biomass and nitrogen-containing biomass is the better carbon source to produce the CDs. Also, this study revealed that N-cCDs and N-xCDs are excellent candidates for fluorescent ink, fabrics identifying, temperature sensing, and Hg 2+ sensing. Due to its poor fluorescence property, N-lCDs is not suitable for fluorescent ink and fabrics identification.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2016
·
IF 3.993
Shi Gang Liu,Na Li,Yu Ling,Bei Hua Kang,Shuo Geng,Nian Bing Li,Hong Qun Luo
We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CARBON
·
2019
·
IF 7.466
Pei Yang,Ziqi Zhu,Tao Zhang,Minzhi Chen,Yizhong Cao,Wei Zhang,Xin Wang,Xiaoyan Zhou,Weimin Chen
The realization of long-wavelength emissions and thoroughly understanding of photoluminescence (PL) mechanism are still huge challenges to be addressed for further development of carbohydrate-derived carbon dots (CDs). Herein, novel CDs with excellent green emission were synthesized from a precursor comprising of xylose and m -phenylenediamine in phosphoric acid solution via a simple microwave-assisted hydrothermal method . The PL efficiency was dependent on the combination of different acids and the precursor as well as the synthesis temperature, while the PL properties were mainly related to the acid base environment of precursor. Optical performance and structural characterization revealed that the oxygen-containing groups and protonated amino groups were mainly responsible for the blue and green emission properties, respectively. Moreover, a multi-center fluorescent mechanism on the different PL performances of xylose-derived CDs was proposed and verified by further investigating the pH-dependent PL behaviors. Based on the switching between green and blue emission in different pH regions, the xylose-derived CDs solution was demonstrated to be a promising fluorescent ink for anti-counterfeit printing. This research open a door for value-added utilization of xylose, as well as providing a facile and green strategy for large-scale preparation of CDs.
研究领域:
材料科学
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光学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
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