EDTA-bonded multi-connected carbon-dots and their Eu³⁺ complex: preparation and optical properties

Abstract

EDTA-bonded multi-connected carbon-dots (EDTA-C-dots) were prepared from carbon dot precursors and complexed with Eu 3+ to give Eu 3+ -coordinated EDTA-bonded multi-connected carbon dots (Eu-EDTA-C-dots). Whereas EDTA-C-dots were readily soluble in DMSO, Eu-EDTA-C-dots could not be easily dissolved in DMSO, water, or other common organic solvents. The newly prepared materials were thoroughly characterized. The X-ray diffraction results showed that no crystalline phase of Eu oxides (europium oxide or europium hydroxide) could be observed in Eu-EDTA-C-dots. The infrared and UV-Vis spectra showed that coordination with Eu 3+ ions did not damage the structure of the EDTA-C-dots.It was found that EDTA could be easily grafted on the surface of carbon dots and EDTA had minimal influence on the photoluminescence of the carbon dot matrix. In contrast, the existence of Eu 3+ ions strongly quenched the photoluminescence of Eu-EDTA-C-dots. The measured and fitted decay lifetime indicated that Eu-EDTA-C-dots possessed two photoluminescence decay processes, i.e., radiative recombination and non-radiative recombination.

Electron/energy co-transfer behavior and reducibility of Cu-chlorophyllin-bonded carbon-dots

“…It is well known that C-dots exhibit weak oxidation or reduction because they can act as both excellent electron acceptors and electron donors. 31,[44][45][46][47] Recently, using Cdots as a catalytic reductant and capping agent, Wang et al have successfully prepared stable silver nanoparticles (Ag NPs). † 46 Since the plasmon absorption of Ag NPs appears mainly in the wavelength range of 350-500 nm, there exists not only electron transfer but also FRET behavior between C-dots and Ag NPs.…”

“…The precursor carbon dots (CDs) were prepared from citric acid and ethylenediamine in an autoclave, and the details can be found in the supporting information. † 31,38 Subsequently, Cuchlorophyllin-bonded carbon dots (denoted as CCPh-CDs) were synthesized as follows: (1) Cu-chlorophyllin (270.0 mg), S-NHS (800.0 mg) and EDC (350.0 mg) were dissolved in 60 mL DMSO at room temperature with stirring; (2) the CDs (500.0 mg) were added into the solution with stirring for 24 hours under light-proof condition; (3) the obtained solution was washed and centrifuged with ethanol for three times; (4) the solid product was vacuum-dried for 10 hours at 40 C and the CCPh-CD1 (Cu 2+ content: 1.21 wt%) has been synthesized.…”

“…Hence, their application is limited by the detachment of CDs from the corresponding nanocomposites in the solvent. In our previous work, the preparation and characterization of EDTA-bonded CDs have been investigated, 31 and herein we investigate the synthesis and characterization of Cu-chlorophyllin-bonded carbon-dots (CCPh-CDs).…”

PEI functionalized NaCeF4:Tb3+/Eu3+ for photoluminescence sensing of heavy metal ions and explosive aromatic nitro compounds

“…The bands around 1640 and 1400 cm À1 are attributed to asymmetrical and symmetrical stretching of the carboxylate (-COO) group. 54 The appearance of these IR bands conrms the presence of EDTA in the NaCeF 4 :Tb 3+ and NaCeF 4 :Tb 3+ /Eu 3+ nanocrystals.…”

When rare earth meets carbon nanodots: mechanisms, applications and outlook

“…It has been widely accepted that there are direct energy transfers from CNDs to Eu 3+ /Tb 3+ , which were preliminarily postulated from the observation of CNDs luminescent quenching upon introducing Eu 3+ . [51][52][53][54] In 2011, Zhao et al reported the quenching effect and decreased lifetime of CNDs upon the addition of Eu 3+ . They attributed this phenomenon to the disruption of the radiative recombination on CNDs surface induced by Eu 3+ , with possible charge-or energy transfer process.…”