The Raman spectrum of thiourea–oxocarbon adducts

Lopes, José Guilherme S.; Oliveira, Luiz Fernando Cappa de; Edwards, Howell G. M.; Santos, Paulo S.

doi:10.1002/jrs.1113

Cited by 35 publications

(8 citation statements)

References 21 publications

(22 reference statements)

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“…Raman spectroscopy has been widely exploited to reveal the association interaction of thiourea and salts. 35,36 In the present article, Raman spectra of 8 wt % thiourea aqueous solutions with different concentrations of NaOH from 0 to 10 wt % are displayed in Figure 3c. In the thiourea aqueous solution, the Raman band at 1486 cm −1 was assigned to the antisymmetrical CN stretching vibration.…”

Section: ■ Results and Discussionmentioning

confidence: 91%

Dissolution and Metastable Solution of Cellulose in NaOH/Thiourea at 8 °C for Construction of Nanofibers

Jiang

Fang

et al. 2017

J. Phys. Chem. B

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To develop a facile approach for the dissolution of cellulose, a novel solvent (9.3 wt % NaOH/7.4 wt % thiourea aqueous solution) was used, for the first time, to dissolve cellulose within 5 min at 8 °C. The results of NMR and Raman spectra demonstrated that stable thiourea···OH complexes were formed through strong hydrogen bonds in NaOH/thiourea at room temperature. Moreover, the strength of the hydrogen bonds in thiourea···OH complexes was much higher than that in urea···OH complexes, and the number of thiourea···OH complexes increased significantly in 9.3 wt % NaOH/7.4 wt % thiourea compared to that in 9.5 wt % NaOH/4.5 wt % thiourea, which dissolved cellulose at -5 °C, leading to the dissolution of cellulose at a relatively high temperature (8 °C). The cellulose that dissolved at such a high temperature was metastable. The results of dynamic light scattering and transmission electron microscope experiments confirmed that the extended cellulose chains and their aggregates coexisted in the dilute cellulose solution. Interestingly, stiff cellulose chains could be self-assembled in parallel to form nanofibers in the metastable cellulose solution, from which cellulose microspheres consisting of nanofibers could be easily produced by inducing heating. This work not only proposed a novel method for the dissolution of cellulose in aqueous system at temperatures over 0 °C but also opened up a new pathway for the construction of nanofibrous cellulose materials.

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Section: ■ Results and Discussionmentioning

confidence: 91%

Dissolution and Metastable Solution of Cellulose in NaOH/Thiourea at 8 °C for Construction of Nanofibers

Jiang

Fang

et al. 2017

J. Phys. Chem. B

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“…The microscopic confocal laser Raman spectra (Figure S9b) indicate that P-2 (SC(NH 2 ) 2 ) has Raman peaks at 485, 1096, and 735/1388 cm –1 , which can be assigned to the NCN asymmetric bending, CN symmetric stretching, and CS symmetric/asymmetric stretching vibrations of SC(NH 2 ) 2 , , respectively. Compared to that of P-2, the Raman spectrum of P-3 has an extra peak at 281 cm –1 , which roughly disappeared in the Raman spectrum of P 4̅ derived from the hydrothermal treatment at 190 °C for 1 h. Since the SnS bond has a very strong peak at ∼316 cm –1 as shown in the Raman spectrum of SnS 2 , it can be concluded that there is no SnS bond formation in P 4̅, and the new peak at 281 cm –1 of P-3 might correspond to the SnN bond in P-3 derived from the rotary evaporation of the mixed solution since N and S atoms in SC(NH 2 ) 2 can coordinate with metal ions.…”

Section: Resultsmentioning

confidence: 99%

Controllable Fabrication of Regular Hexagon-Shaped SnS₂ Nanoplates and Their Enhanced Visible-Light-Driven H₂ Production Activity

Wang

Zhou³

et al. 2018

ACS Appl. Nano Mater.

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SnS 2 nanoplate-like products were fabricated via a facile hydrothermal process of a mixed solution containing SnCl 4 and thiourea (SC(NH 2 ) 2 ) without organic capping agent, and their composition, crystallinity, and morphology can be adjusted by varying the SC(NH 2 ) 2 /SnCl 4 molar ratio. In particular, regular hexagon-shaped SnS 2 nanoplates with an average size of ∼275 nm and thickness of ∼56 nm were attained when the SC(NH 2 ) 2 / (SnCl 4 ) molar ratio is 6:1. The obtained SnS 2 nanoplates exhibit layered structures with exposed {001} facets and a single-crystalline feature, and its growth mechanism was proposed according to the hydrothermal time-dependent experimental results. The regular hexagon-shaped SnS 2 nanoplates achieve high photocatalytic H 2 production activity of 356 μmol h −1 under visible light (λ ≥ 420 nm) irradiation, much better than that of the irregular nanoplate-like products. The higher crystallinity and fewer defects of the regular hexagon-shaped SnS 2 nanoplates compared to the irregular ones can more efficiently retard the photogenerated charge recombination, while the S atoms with higher density in the exposed {001} facets might be beneficial for the formation of H bonds with H 2 O molecules, which then cause good dispersity and photocatalytic activity for H 2 production of the SnS 2 nanoplates. These results demonstrate the potential application of SnS 2 nanoplates in the photocatalytic H 2 production field, and might provide guidance to the controllable syntheses of the family of MS 2 photocatalysts with a highly efficient H 2 production property.

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“…For instance, the very characteristic mode at 745 cm 1 in the spectrum of (I), assigned to the squarate ring breathing appears in the free C 4 O 4 2 at 718 cm 1 and in thiourea adduct at 725 cm 1 . 1 This mode corresponds to the strongest Raman band in the spectra of squarate and its derivatives. For the monoanion of (I), this band is of only medium intensity since other modes of the squaraine are now more enhanced in the extended chromophore.…”

Section: Resultsmentioning

confidence: 99%

Resonance Raman spectra of hydroxyphenyl squaraines: acid–base versus aggregation equilibria

Lopes

Farani

Oliveira

et al. 2006

J Raman Spectroscopy

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The optical and resonance Raman spectra (RR) of bis(phloroglucinol)squaraine (I) and bis(resorcinol)squaraine (II) were investigated, revealing that the equilibria between the neutral and anionic species present in solution explain the experimental observations much better than the previously proposed aggregation equilibria. In particular, the RR spectra were invaluable to assign characteristic modes of (I) and its monoanion, since the tuning of the excitation line to the electronic transition band of the neutral or monoanionic specie leads to the enhancement of the respective modes that are exclusive of each species. In addition, small angle X-ray scattering (SAXS) experiments with (I) did not show any evidence of aggregation.

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The Raman spectrum of thiourea–oxocarbon adducts

Cited by 35 publications

References 21 publications

Dissolution and Metastable Solution of Cellulose in NaOH/Thiourea at 8 °C for Construction of Nanofibers

Dissolution and Metastable Solution of Cellulose in NaOH/Thiourea at 8 °C for Construction of Nanofibers

Controllable Fabrication of Regular Hexagon-Shaped SnS₂ Nanoplates and Their Enhanced Visible-Light-Driven H₂ Production Activity

Resonance Raman spectra of hydroxyphenyl squaraines: acid–base versus aggregation equilibria

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The Raman spectrum of thiourea–oxocarbon adducts

Cited by 35 publications

References 21 publications

Dissolution and Metastable Solution of Cellulose in NaOH/Thiourea at 8 °C for Construction of Nanofibers

Dissolution and Metastable Solution of Cellulose in NaOH/Thiourea at 8 °C for Construction of Nanofibers

Controllable Fabrication of Regular Hexagon-Shaped SnS2 Nanoplates and Their Enhanced Visible-Light-Driven H2 Production Activity

Resonance Raman spectra of hydroxyphenyl squaraines: acid–base versus aggregation equilibria

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Controllable Fabrication of Regular Hexagon-Shaped SnS₂ Nanoplates and Their Enhanced Visible-Light-Driven H₂ Production Activity