Improved complexation of paraquats with crown ether‐based pyridyl cryptands. Issue 6 (11th December 2017)

• Record Type: Journal Article
• Authors: Price, Terry L.; Slebodnick, Carla; Gibson, Harry W.
• Is Part Of: Heteroatom chemistry. Volume 28:Issue 6(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-12-11
• Subjects: cryptand -- enthalpy‐entropy compensation -- paraquat -- TFSI counterion; Heterocyclic chemistry -- Periodicals; 547.59
• DOI: 10.1002/hc.21406
• Languages: English
• ISSNs: 1042-7163

Abstract

Abstract: The commonly used paraquat guest N, N ′‐dimethyl‐4, 4′‐bipyridinium bis(hexafluorophosphate) (7 ) was targeted for structural alterations to improve the binding constants with crown ethers and cryptands. The association constant was improved by one order of magnitude (to K a = 1.00 × 10 6 mol L −1 ) with the dibenzo‐30‐crown‐10 pyridyl cryptand host5 by changing the N‐methyl groups to benzyl and the counterions from PF6 to TFSI, that is, 11 . Moreover, through addition of a p ‐bromobenzyloxy moiety on the 4‐position of the pyridyl ring of cryptand18, an association constant of K a = 5.35 × 10 6 mol L −1 was achieved with paraquat11 .