Aggregation-induced red shift in N,S-doped chiral carbon dot emissions for moisture sensing

Arshad, Farwa; Sk, Palashuddin

doi:10.1039/c9nj03009c

Cited by 47 publications

(30 citation statements)

References 37 publications

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“…Besides citric acid, which has been most commonly used as a carbon co-source for chiral carbon dots synthesized from L-/D-cysteine, a number of other achiral precursors have been reported, such as ethylene diamine 63 , 143 , Jeffamine ® ED-900 144 , 145 , sucrose 146 , 147 , arginine 58 , and o-phenylenediamine 59 . While all the abovementioned methods used water as a solvent, Arshad et al synthesized chiral carbon dots from cysteine and p-benzoquinone in ethanol by microwave treatment 148 . The resulting dots were smaller (2.7 nm in diameter) and highly uniform.…”

Section: Synthesis Of Chiral Carbon Dotsmentioning

confidence: 99%

Chiral carbon dots: synthesis, optical properties, and emerging applications

2022

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Carbon dots are luminescent carbonaceous nanoparticles that can be endowed with chiral properties, making them particularly interesting for biomedical applications due to their low cytotoxicity and facile synthesis. In recent years, synthetic efforts leading to chiral carbon dots with other attractive optical properties such as two-photon absorption and circularly polarized light emission have flourished. We start this review by introducing examples of molecular chirality and its origins and providing a summary of chiroptical spectroscopy used for its characterization. Then approaches used to induce chirality in nanomaterials are reviewed. In the main part of this review we focus on chiral carbon dots, introducing their fabrication techniques such as bottom-up and top-down chemical syntheses, their morphology, and optical/chiroptical properties. We then consider emerging applications of chiral carbon dots in sensing, bioimaging, and catalysis, and conclude this review with a summary and future challenges.

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Section: Synthesis Of Chiral Carbon Dotsmentioning

confidence: 99%

Chiral carbon dots: synthesis, optical properties, and emerging applications

2022

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“…Two absorption bands peaking at 1800 cm −1 and 1700 cm −1 were assigned to the C�O bond of anhydride structures, while three peaks at 1550 cm −1 , 1620 cm −1 , and 1660 cm −1 were ascribed to amide (-CONH-) groups. Additionally, two peaks at 1450 cm −1 and 1350 cm −1 were attributed to stretching vibrations of S�O and aromatic amine C-N bonds [6,20,23].…”

Section: Resultsmentioning

confidence: 99%

“…At this moment, a detailed mechanism accounting for this blue quenching phenomenon is still ambiguous. Arshad and Sk studied the effects of the solvent on the emission of CQDs and pointed out that the aggregation of CQDs leads to enhancement in red emission and reduction in blue emission [20]. Probably, because CQDs absorb light significantly in the blue region (Figure 2(a)), CQD aggregation enhances energy transfer among CQDs so that emitted blue light was reabsorbed, while longer-wavelength light was less affected; this mechanism is known as Förster resonance energy transfer (FRET) [19,22].…”

Section: Resultsmentioning

confidence: 99%

“…ere have been some reports demonstrating the effects of CQD aggregation on the absorption and emission of composites made of CQDs and polymers [3,19]. π-π interaction in the solids enhances energy transfer among CQDs and is able to create new electronic states performing emission at long-wavelength regions [20][21][22]. Notably, in [21], the PL spectrum of colloidal CQDs exhibits strong excitation dependence in the UV to blue region, while that of solid CQDs shows fair excitation independence in the orange to red region.…”

Section: Introductionmentioning

confidence: 99%

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Excitation-Independent Emission of Carbon Quantum Dot Solids

Dũng

Phan

Nguyen

2020

Advances in Materials Science and Engineering

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Solid assemblies of carbon quantum dots (CQDs) are important for diverse applications including LEDs, solar cells, and photosensors; their optical and electrical properties have not been explored yet. Herein, we used amphiphilic CQDs synthesized from citric acid and thiourea by a solvothermal method to fabricate CQD solid films. Optical properties of CQDs studied by UV-Vis and photoluminescence spectroscopies indicate that CQDs possess three different emission centers at 425 nm, 525 nm, and 625 nm originating from C sp2 states, N-states, and S-states, respectively. In a solid state, π-π stacking quenched the blue emission, while the red emission increased. Importantly, CQD films exhibited excitation independence, which is important to design solid-state lighting applications.

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“…The solution phase detection technique has been used to sense various analytes such as small molecules, intracellular pH, macromolecules, cations, anions and moisture content. 16,79,[230][231][232][233][234][235][236] Solid phase detection, on the other hand, corresponds to utilization of fluorescent paper based or fingerprint-based sensing of various biomolecules, explosive compounds etc. 16,237,238 Apart from colorimetric detection, recent reports on the use of Cdots as an electrochemical sensing platform are worthy of mention.…”

Section: Sensing Application Of Cdotsmentioning

confidence: 99%