Ying-Chun He*, Hong-Bo Tong, Cheng-Gang Xu, Zhen-Xing Ren, Yong-Zhao Wang, Yan-Mei Yan, and Meng-Liang Wang*. Highly Selective Coextraction of H⁺/SO₄^2- Using a Strapped Calix[4]pyrrole, Organic Letters, 2023,  25, 1737−1741