Formation of Citrazinic Acid Ions and Their Contribution to Optical and Magnetic Features of Carbon Nanodots: A Combined Experimental and Computational Approach

Mocci, Francesca; Olla, Chiara; Cappai, Antonio; Corpino, Riccardo; Ricci, Pier Carlo; Chiriu, Daniele; Salis, M.; Carbonaro, Carlo Maria

doi:10.3390/ma14040770

Cited by 11 publications

(16 citation statements)

References 41 publications

(75 reference statements)

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“…Indeed, if we consider the case of IPCA, a reaction of cyclization between CA and ethylene-diamine was hypothesized to produce the molecule that acts as a seed for the formation of the CDs and cause, with its aggregates, the excitation dependent emission features recorded in those systems [28,67,68]. In a similar way, we recently studied the formation of CZA in the synthesis of CA and urea (the reference system in the present study) and we demonstrated that the formation of various ionic species and different aggregates can explain the optical features of citric acid derived CDs [65,66,69,70]. If we assumed the same reaction paths reported for CZA and IPCA, more than one product could be embedded during the CD formation.…”

Section: Discussionsupporting

confidence: 62%

“…The whole set of experimentally observed features here reported calls for the formation of CDs: the rounded nanoparticle observed by means of TEM (mean size 5-12 nm), the measured D and G vibrational bands, the absorption band around 350 nm, the excitation dependent emission spectra and the non-single exponential decay times. As already proposed for parent CA derived systems, those features are related to the formation of some specific molecule, as the IPCA and CZA molecules reported in those cases [11,28,65,66]. Starting from this consideration, we hypothesized that the pyridinone molecules produced during the synthesis of CA and hydrazine, their aggregated forms or some polymeric structure derived by further reactions of the monomer units can be incorporated into the structure of the CDs and produce the optical…”

Section: Discussionmentioning

confidence: 72%

“…None of the precursor vibrational modes were present in both the 1350-1400 and 1550-1600 cm −1 regions, whilst the pyridinone structure shows two bands at 1400 and 1580 cm −1 . To further explore the scenario, we considered for the Hy-CD case the formation of some typical aggregates already proposed for the CZA and IPCA systems [65][66][67][68][69], namely the parallel and anti-parallel stack dimers and the head-to-tail in plane dimer. We calculated the absorption spectra for the aggregate systems at a fixed distance between the monomer units, namely at 0.366 nm for the stack dimers and at 0.288 for the heat-to-tail dimers, assuming the same geometries of the parent CZA system.…”

Section: Er Review 11 Of 20mentioning

confidence: 99%

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Towards N–N-Doped Carbon Dots: A Combined Computational and Experimental Investigation

et al. 2022

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The introduction of N doping atoms in the carbon network of Carbon Dots is known to increase their quantum yield and broaden the emission spectrum, depending on the kind of N bonding introduced. N doping is usually achieved by exploiting amine molecules in the synthesis. In this work, we studied the possibility of introducing a N–N bonding in the carbon network by means of hydrothermal synthesis of citric acid and hydrazine molecules, including hydrated hydrazine, di-methylhydrazine and phenylhydrazine. The experimental optical features show the typical fingerprints of Carbon Dots formation, such as nanometric size, excitation dependent emission, non-single exponential decay of photoluminescence and G and D vibrational bands in the Raman spectra. To explain the reported data, we performed a detailed computational investigation of the possible products of the synthesis, comparing the simulated absorbance spectra with the experimental optical excitation pattern. The computed Raman spectra corroborate the hypothesis of the formation of pyridinone derivatives, among which the formation of small polymeric chains allowed the broad excitation spectra to be experimentally observed.

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Section: Discussionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 72%

Section: Er Review 11 Of 20mentioning

confidence: 99%

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Towards N–N-Doped Carbon Dots: A Combined Computational and Experimental Investigation

et al. 2022

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“…Indeed the Fourier-transform infrared spectrum reported by Sarkar do show two large bands that could be partly related to H-bonding between monomer units besides the larger contribution of OH groups typically found in this vibrational range that hampers the Raman analysis of CZA water solution down to 3500 cm –1 . In a very recent paper, we showed that, besides the formation of different ionic species, aggregation is also important for the magnetic features of CZA-related carbon nanodots …”

Section: Resultsmentioning

confidence: 99%

“…In a very recent paper, we showed that, besides the formation of different ionic species, aggregation is also important for the magnetic features of CZA-related carbon nanodots. 51 3.6. Raman and IR Spectra.…”

Section: Experimental and Computationalmentioning

confidence: 99%

Insight into the Molecular Model in Carbon Dots through Experimental and Theoretical Analysis of Citrazinic Acid in Aqueous Solution

et al. 2021

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The molecular emission model is the most accredited one to explain the emission properties of carbon dots (CDs) in a low-temperature bottom-up synthesis approach. In the case of citric acid and urea, the formation of a citrazinic acid (CZA) single monomer and oligomers is expected to affect the optical properties of the CDs. It is therefore mandatory to elucidate the possible role of weak bonding interactions in determining the UV absorption spectrum of some molecular aggregates of CZA. Although this carboxylic acid is largely exploited in the synthesis of luminescent CDs, a full understanding of its role in determining the final emission spectra of the produced CDs is still very far to be achieved. To this aim, by relying on purely first-principles density functional theory calculations combined with experimental optical characterization, we built and checked the stability of some molecular aggregates, which could possibly arise from the formation of oligomers of CZA, mainly dimers, trimers, and some selected tetramers. The computed vibrational fingerprint of the formation of aggregates is confirmed by surface-enhanced Raman spectroscopy. The comparison of experimental data with calculated UV absorption spectra showed a clear impact of the final morphology of the aggregates on the position of the main peaks in the UV spectra, with particular regard to the 340 nm peak associated with n-π* transition.

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Blue‐Emitting Boron‐ and Nitrogen‐Doped Carbon Dots for White Light‐Emitting Electrochemical Cells

Cavinato,

Kost,

Campos‐Jara

et al. 2024

Advanced Optical Materials

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This work describes the first use of blue‐emitting boron‐ and nitrogen‐doped carbon dots (BN‐CDs), rationalizing their photoluminescence behavior in solution and ion‐based thin‐films to prepare white light‐emitting electrochemical cells (LECs). In detail, a cost‐effective and scalable water‐based microwave‐assisted synthesis procedure is set for BN‐CDs featuring an amorphous carbon‐core doped with N and B. While they show a bright (photoluminescence quantum yield of 42%) and excitation‐independent blue‐emission (440 nm) in solution related to emitting n−π* surface states, they are not emissive in thin‐films due to aggregation‐induced quenching. Upon fine‐tuning the film composition (ion‐based host), an excitation dependent emission covering the whole visible range is noted caused by interaction of the ion electrolyte with the peripheral functionalization of the BN‐CDs. Moreover, the efficient energy transfer from the host to the BN‐CDs emitting species enabled good performing LECs with white emission (x/y CIE coordinates of 0.30/0.35, correlated color temperature of 6795 K, color rendering index of 87) and maximum luminance of 40 cd m−2, and stabilities of a few hours. This represents a significant improvement compared to the prior‐art monochromatic CD‐based LECs with similar brightness levels, but stabilities of <1 min.

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Formation of Citrazinic Acid Ions and Their Contribution to Optical and Magnetic Features of Carbon Nanodots: A Combined Experimental and Computational Approach

Cited by 11 publications

References 41 publications

Towards N–N-Doped Carbon Dots: A Combined Computational and Experimental Investigation

Towards N–N-Doped Carbon Dots: A Combined Computational and Experimental Investigation

Insight into the Molecular Model in Carbon Dots through Experimental and Theoretical Analysis of Citrazinic Acid in Aqueous Solution

Blue‐Emitting Boron‐ and Nitrogen‐Doped Carbon Dots for White Light‐Emitting Electrochemical Cells

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