In:
Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), Vol. 23, No. 47 ( 2021), p. 26750-26760
Abstract:
UV/Vis absorption data of ( E )-4-(2-[5-{4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl}thiene-2-yl]vinyl)-2-(dicyano-methylene)-3-cyano-5,5-dimethyl-2,5-dihydrofuran (ThTCF) as a solvatochromic probe is applied to examine the anion coordination strength ( e.g. of N(CN) 2 , BF 4 , PF 6 , N(Tf) 2 , CF 3 COO) as a function of the cation structure of ionic liquids. Several 1- n -alky-3-methylimidazolium- and tetraalkylammonium CH 3 -NR 3 + -based ILs with different n -alkyl chain lengths (R = –C 4 H 9 , –C 6 H 11 , –C 8 H 17 , –C 10 H 21 ) are considered. UV/Vis absorption data of ThTCF show subtle correlations with hydrogen bond accepting (HBA) ability-related measurands such as Kamlet–Taft β , Freire's E HB , and Laurence β 1 parameter as a function of anion and cation structure. The different influence of the n -alkyl chain length of imidazolium- and tetraalkylammonium-based ILs on the dipolarity and HBA strength is confirmed by comparison with the 14 N isotropic hyperfine coupling constants ( A iso ) of a positively ( CATI ) and negatively charged spin probe ( TSKCr ) of TEMPO-type [(2,2,6,6-tetramethylpiperidin-1-yl)oxyl] and quantum chemically derived dipoles of the cations. The A iso values correlate with the absorption energy of ThTCF and E HB , but in different ways depending on the anion or charge of the spin probe. In a final discussion of the β , E HB , and β 1 scales in relation to ThTCF, the importance of the molar concentration N of ionic liquids for the physical significance of the respective parameters is discussed.
Type of Medium:
Online Resource
ISSN:
1463-9076
,
1463-9084
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
1476283-3
detail.hit.zdb_id:
1476244-4
detail.hit.zdb_id:
1460656-2
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