Host-Guest Complexation of Amphiphilic Molecules at the Air-Water Interface Prevents Oxidation by Hydroxyl Radicals and Singlet Oxygen
The oxidation of antioxidants by oxidizers imposes great challenges to both living organisms and the food industry. Here we show that the host–guest complexation of the carefully designed, positively charged, amphiphilic guanidinocalixarene pentadodecyl ether (GC5A‐12C) and negatively charged oleic acid (OA), a well‐known cell membrane antioxidant, prevents the oxidation of the complex monolayers at the air–water interface from two potent oxidizers hydroxyl radicals (OH) and singlet delta oxygen (SDO). OH is generated from the gas phase and attacks from the top of the monolayer, while SDO is generated inside the monolayer and attacks amphiphiles from a lateral direction. Field‐induced droplet ionization mass spectrometry results have demonstrated that the host–guest complexation achieves steric shielding and prevents both types of oxidation as a result of the tight and "sleeved in" physical arrangement, rather than the chemical reactivity, of the complexes.
© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Issue Online: 21 July 2020; Version of Record online: 25 May 2020; Accepted manuscript online: 06 April 2020; Manuscript revised: 20 March 2020; Manuscript received: 27 January 2020. X.Z. acknowledges the National Key R&D Program of China (2018YFE0115000) and the NSF of Tianjin City (19JCYBJC19600). This work was supported by the Beckman Institute at Caltech and by NSF grant CHE‐1508825 (J.L.B.). NSFC (51873090 and 21672112) and the Fundamental Research Funds for the Central Universities are gratefully acknowledged. The authors declare no conflict of interest.
Supplemental Material - anie202001355-sup-0001-misc_information.pdf