Synthesis of distinctly thiol-capped CdTe quantum dots under microwave heating: multivariate optimization and characterization

Ribeiro, David S.M.; Souza, Gustavo C. S. de; Melo, Armindo; Soares, José X.; Rodrigues, S. Sofia M.; Araújo, Alberto N.; Montenegro, M.C.B.S.M.; Santos, João L.M.

doi:10.1007/s10853-016-0610-4

Cited by 27 publications

(10 citation statements)

References 28 publications

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“…Additionally, according to the results shown in Table 2, by raising the temperature from 95 to 125, the wavelength of maximum absorbance corresponding to the first excitonic transition, the wavelength of maximum emission and the corresponding nanoparticles sizes also increased. The obtained results are in agreement with those obtained by Ribeiro et al [16] thus confirming that by fixing the time of synthesis, the temperature increment promotes an increasing growth rate. Additionally, the quantum yields (QY) of the nanoparticles synthesized at 95, 105 and 125 °C were 13.3%, 27.2% and 63.6%, respectively.…”

Section: Characterization Of the As-prepared Cdte Qds Capped With Mpasupporting

confidence: 92%

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Multiplexed analysis combining distinctly-sized CdTe-MPA quantum dots and chemometrics for multiple mutually interfering analyte determination

Bittar

Ribeiro

Páscoa

et al. 2017

Talanta

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Semiconductor quantum dots (QDs) have demonstrated a great potential as fluorescent probes for heavy metals monitoring. However, their great reactivity, whose tunability could be difficult to attain, could impair selectivity yielding analytical results with poor accuracy. In this work, the combination in the same analysis of multiple QDs, each with a particular ability to interact with the analyte, assured a multi-point detection that was not only exploited for a more precise analyte discrimination but also for the simultaneous discrimination of multiple mutually interfering species, in the same sample. Three different MPA-CdTe QDs (2.5, 3.0 and 3.8nm) with a good size distribution, confirmed by the FWHM values of 48.6, 55.4 and 80.8nm, respectively, were used. Principal component analysis (PCA) and partial least squares regression (PLS) were used for fluorescence data analysis. Mixtures of two MPA-CdTe QDs, emitting at different wavelength namely 549/566, 549/634 and 566/634nm were assayed. The 549/634nm emitting QDs mixture provided the best results for the discrimination of distinct ions on binary and ternary mixtures. The obtained RMSECV and RCV values for the binary mixture were good, namely, from 0.01 to 0.08mgL and from 0.74 to 0.89, respectively. Regarding the ternary mixture the RMSECV and RCV values were good for Hg(II) (0.06 and 0.73mgL, respectively) and Pb(II) (0.08 and 0.87mg L, respectively) and acceptable for Cu(II) (0.02 and 0.51mgL, respectively). In conclusion, the obtained results showed that the developed approach is capable of resolve binary and ternary mixtures of Pb (II), Hg (II) and Cu (II), providing accurate information about lead (II) and mercury (II) concentration and signaling the occurrence of Cu (II).

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Section: Characterization Of the As-prepared Cdte Qds Capped With Mpasupporting

confidence: 92%

“…Three different diameters of MPA capped CdTe QDs were synthesized by resorting to the one-pot MW-assisted aqueous synthetic route as proposed by Ribeiro et al [16]. Briefly, an equimolar quantity of CdCl 2 and MPA (1.25 × 10 −3 mol) was mixed in 125 mL of deionized water.…”

Section: Synthesis Of Mpa Capped Cdte Qds Assisted By Microwave Irradiationmentioning

confidence: 99%

Multiplexed analysis combining distinctly-sized CdTe-MPA quantum dots and chemometrics for multiple mutually interfering analyte determination

Bittar

Ribeiro

Páscoa

et al. 2017

Talanta

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“…A useful tool to rationally guide the optimization of complex processes is the design of experiment (DoE) approach. Its cornerstone is the assumption that the outcome of a reaction can be described by a mathematical equation [52,53]. Based on the experimental data, a mathematical model can be established to describe the studied system and, consequently, to predict the experimental conditions, which provide the optimum outcome [54][55][56].…”

Section: Introductionmentioning

confidence: 99%

Rationally designed synthesis of bright AgInS2/ZnS quantum dots with emission control

et al. 2020

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In the blossoming field of Cd-free semiconductor quantum dots (QDs), ternary I-III-VI QDs have received increasing attention due to the ease of the environmentally friendly synthesis of high-quality materials in water, their high photoluminescence (PL) quantum yields (QYs) in the red and near infrared (NIR) region, and their inherently low toxicity. Moreover, their oxygen-insensitive long PL lifetimes of up to several hundreds of nanoseconds close a gap for applications exploiting the compound-specific parameter PL lifetime. To overcome the lack of reproducible synthetic methodologies and to enable a design-based control of their PL properties, we assessed and modelled the synthesis of high-quality MPA-capped AgInS 2 /ZnS (AIS/ZnS) QDs. Systematically refined parameters included reaction time, temperature, Ag:In ratio, S:In ratio, Zn:In ratio, MPA:In ratio, and pH using a design-of-experiment approach. Guidance for the optimization was provided by mathematical models developed for the application-relevant PL parameters, maximum PL wavelength, QY, and PL lifetime as well as the elemental composition in terms of Ag:In:Zn ratio. With these experimental data-based models, MPA:In and Ag:In ratios and pH values were identified as the most important synthesis parameters for PL control and an insight into the connection of these parameters could be gained. Subsequently, the experimental conditions to synthetize QDs with tunable emission and high QY were predicted. The excellent agreement between the predicted and experimentally found PL features confirmed the reliability of our methodology for the rational design of high quality AIS/ZnS QDs with defined PL features. This approach can be straightforwardly extended to other ternary and quaternary QDs and to doped QDs.

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“…QDs stabilized with four different SL were synthesized: two bearing –COOH groups (MPA and TGA), and two bearing –SO 3 groups (sodium 3-mercaptopropanesulfonate (MPS) and sodium 2-mercaptoethanesulfonate (MES). SL with carboxylic groups are the most studied in water-soluble QDs synthesis, including their behavior in aqueous media and well-established functionalization reactions 17,18,22,23 . However, to our best knowledge there are no studies of MPS for CdTe synthesis even though this group has low pKa values, which opens a potential of their use in a larger pH range.…”

Section: Introductionmentioning

confidence: 99%

Ligand induced switching of the band alignment in aqueous synthesized CdTe/CdS core/shell nanocrystals

Vale¹,

Mourão²,

Bettini³

et al. 2019

Sci Rep

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CdTe/CdS core/shell quantum dots (QDs) are formed in aqueous synthesis via the partial decomposition of hydrophilic thiols, used as surface ligands. In this work, we investigate the influence of the chemical nature (functional group and chain length) of the used surface ligands on the shell formation. Four different surface ligands are compared: 3-mercaptopropionic acid, MPA, thioglycolic acid, TGA, sodium 3-mercaptopropanesulfonate, MPS, and sodium 2-mercaptoethanesulfonate, MES. The QD growth rate increases when the ligand aliphatic chain length decreases due to steric reasons. At the same time, the QDs stabilized with carboxylate ligands grow faster and achieve higher photoluminescence quantum yields compared to those containing sulfonate ligands. The average PL lifetime of TGA and MPA capped QDs is similar (≈20 ns) while in the case of MPS shorter (≈15 ns) and for MES significantly longer (≈30 ns) values are measured. A detailed structural analysis combining powder X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) indicates the existence of two novel regimes of band alignment: in the case of the mercaptocarboxylate ligands the classic type I band alignment between the core and shell materials is predominant, while the mercaptosulfonate ligands induce a quasi-type II alignment (MES) or an inverted type I alignment (MPS). Finally, the effect of the pH value on the optical properties was evaluated: using a ligand excess in solution allows achieving better stability of the QDs while maintaining high photoluminescence intensity at low pH.

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Synthesis of distinctly thiol-capped CdTe quantum dots under microwave heating: multivariate optimization and characterization

Cited by 27 publications

References 28 publications

Multiplexed analysis combining distinctly-sized CdTe-MPA quantum dots and chemometrics for multiple mutually interfering analyte determination

Multiplexed analysis combining distinctly-sized CdTe-MPA quantum dots and chemometrics for multiple mutually interfering analyte determination

Rationally designed synthesis of bright AgInS2/ZnS quantum dots with emission control

Ligand induced switching of the band alignment in aqueous synthesized CdTe/CdS core/shell nanocrystals

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