Aromatic helical receptors P-1 and P-2 were slightly modified by aerobic oxidation to afford new receptors P-7 and P-8 with right-handed helical cavities. This subtle modification induced significant changes in the binding properties for chiral guests. Specifically, P-1 was reported to bind d-tartaric acid (Ka=35500 M−1), used as a template, much strongly than l-tartaric acid (326 M−1). In contrast, its modified receptor P-7 exhibited significantly reduced affinities for d-tartaric acid (3600 M−1) and l-tartaric acid (125 M−1). More dramatic changes in the affinities and selectivities were observed for P-2 and P-8 upon binding of polyol guests. P-2 was determined to selectively bind d-sorbitol (52000 M−1) over analogous guests, but P-8 showed no binding selectivity: d-sorbitol (1890 M−1), l-sorbitol (3330 M−1), d-arabitol (959 M−1), l-arabitol (4970 M−1) and xylitol (4960 M−1) in 5% (v/v) DMSO/CH2Cl2 at 25±1 °C. These results clearly demonstrate that even subtle post-modifications of synthetic receptors may significantly alter their binding affinities and selectivities, in particular for guests of long and flexible chains.
|Number of pages||9|
|Journal||Chemistry - An Asian Journal|
|Publication status||Published - 2021 Oct 4|
Bibliographical noteFunding Information:
This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (2018R1A2A1A05077048). The authors acknowledge the Pohang Accelerator Laboratory (PAL) for beam line use (2019‐2nd‐2D‐003, 2020–1st‐2D‐007, 2021–1st‐2D‐043).
© 2021 Wiley-VCH GmbH
All Science Journal Classification (ASJC) codes
- Organic Chemistry