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https://hdl.handle.net/10316/101241
Título: | Selective conformational control by excitation of NH imino vibrational antennas | Autor: | Góbi, Sándor Reva, Igor Csonka, István Pál Nunes, Cláudio M Tarczay, György Fausto, Rui |
Data: | 7-Dez-2019 | Editora: | Royal Society of Chemistry | Projeto: | info:eu-repo/grantAgreement/POCI-01-0145-FEDER-016617/PT info:eu-repo/grantAgreement/POCI-01-0145-FEDER-028973/PT info:eu-repo/grantAgreement/FCT/UID/QUI/0313/2019 info:eu-repo/grantAgreement/EC/H2020/654148/EU/The Integrated Initiative of European Laser Research Infrastructures CENTRO-01-0145-FEDER-022124 |
Título da revista, periódico, livro ou evento: | Physical Chemistry Chemical Physics | Volume: | 21 | Número: | 45 | Resumo: | An imino group was used for the first time as a vibrational antenna to manipulate molecular conformations. Imino-thiol isomers of thioacetamide were generated upon UV-irradiation of its amino-thione tautomer isolated in argon matrices at 11 K. Selective and reversible conformational isomerizations were induced by narrowband near-IR irradiation tuned at the frequencies of the 2ν(NH) first stretching overtone of each imino-thiol isomer. The conformational isomerization concerns the change in the orientation of a remote -SH group, while the orientation of the imino (C[double bond, length as m-dash]NH) group remains the same. Supported by quantum chemical anharmonic computations, this allowed for a reliable, isomer-selective vibrational assignment of the four imino-thiol isomers extending now over the full mid-IR and near-IR ranges. It was found that the experimental IR intensities of the 2ν(NH) first stretching overtones (computed 4-5 km mol-1) of the imino-thiol forms are comparable to those of the ν(NH) stretching fundamentals (computed 2-4 km mol-1). This is the first time such a phenomenon is reported for an imine molecule. The kinetics of conformational isomerization was monitored in situ, indicating that the irradiation-induced processes are significantly faster than the tunneling-driven spontaneous cis-trans rotamerization of the -SH group. Quantum yields for the rotamerizations of the -SH group resulting from the vibrational excitation of a remote -NH group were estimated and found to be comparable to those observed for matrix-isolated carboxylic acids and amino acids, where conformational changes of the -OH group were induced by the direct vibrational excitation of 2ν(OH) first stretching overtones. | URI: | https://hdl.handle.net/10316/101241 | DOI: | 10.1039/c9cp05370k | Direitos: | embargoedAccess |
Aparece nas coleções: | I&D CQC - Artigos em Revistas Internacionais |
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Ficheiro | Descrição | Tamanho | Formato | |
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PCCP-2019-21-24935.pdf | 3.59 MB | Adobe PDF | Ver/Abrir |
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