resumo
The state of aggregation at room temperature of tert-butanol (TBH) and perfluoro tert-butanol (TBF) liquid mixtures is assessed by vibrational spectroscopy (Raman and infrared) and X-ray diffraction and analyzed using density functional theory (DFT) and molecular dynamics (MD) simulations. It is shown that larger clusters (mostly tetramers) of TBH are destroyed upon dilution with TBF. Small oligomers, monomers, and mainly heterodimers are present at the equimolar concentration. At variance with slightly interacting solvents, the signature of hetero-oligomers is shown by the appearance of a new broad band detected in the infrared region. The same spectral observation is detected for mixtures of other hydrogenated alcohols (methanol and 1-butanol). The new infrared feature is unaffected by dilution in a polar solvent (CDCl3) in a high-concentration domain, allowing us to assign it to the signature of small hetero-oligomers. MD simulations are used to assess the nature of the species present in the mixture (monomers and small hetero-oligomers) and to follow the evolution of their population upon the dilution. Combining MD simulations with DFT calculations, the infrared spectral profile is successfully analyzed in equimolecular mixtures. This study shows that TBF is a structure breaker of hydrogen-bonded alcohol networks and that the TBF (donor)-TBH (acceptor) heterodimer is the dominant species in an extended range of concentration, centered in the vicinity of the equimolar fraction.
palavras-chave
T-BUTYL ALCOHOL; GAS-PHASE; ELECTRICAL ANHARMONICITY; VANDERWAALS INTERACTIONS; CARBON-TETRACHLORIDE; COMPUTER-SIMULATION; VIBRATIONAL-SPECTRA; AQUEOUS-SOLUTIONS; SELF-ASSOCIATION; BONDED COMPLEX
categoria
Chemistry
autores
Cabaco, MI; Besnard, M; Cruz, C; Morgado, P; Silva, GMC; Filipe, EJM; Coutinho, JAP; Danten, Y
nossos autores
Gonçalo Miguel Carvalho da Silva
Investigador Júnior
agradecimentos
The authors thank Professor Laura Ilharco, Marta Coelho, and Dr. Thierry Buffeteau for providing infrared facilities. They are indebted to Professor Jack Yarwood for critically reading the manuscript and for his comments and useful discussions. The authors gratefully acknowledge the support provided by the HPC resources and allocations of computing time from GENCI (IDRIS) and the facilities of the Mesocentre de Calcul Informatique Aquitain (MCIA) of the University of Bordeaux and des Pays de l'Adour. This work was partly developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. Centro de Quimica Estrutural is funded by Fundacao para a Ciencia e a Tecnologia.project UID/QUI/00100/2019. The authors also acknowledge financial support from FCT through CeFEMA strategic projects UID/CTM/04540/2013 and UID/CTM/04540/2019; and European Union and FCT through Grant MERA-NET2/0006/2016 (CellColor).