Recognition with metallo cavitands

Faiz-Ur Rahman; Yong-Sheng Li; Ioannis D Petsalakis; Giannoula Theodorakopoulos; Julius Rebek Jr; Yang Yu

doi:10.1073/pnas.1909154116

Recognition with metallo cavitands

Proc Natl Acad Sci U S A. 2019 Sep 3;116(36):17648-17653. doi: 10.1073/pnas.1909154116. Epub 2019 Aug 19.

Authors

Faiz-Ur Rahman^{1

2}, Yong-Sheng Li^{1

2}, Ioannis D Petsalakis³, Giannoula Theodorakopoulos³, Julius Rebek Jr^{4

2

5

6}, Yang Yu^{4

2}

Affiliations

¹ Center for Supramolecular Chemistry & Catalysis, Shanghai University, Shanghai 200444, China.
² Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, China.
³ Theoretical and Physical Chemistry Institute, The National Hellenic Research Foundation, Athens 11635, Greece.
⁴ Center for Supramolecular Chemistry & Catalysis, Shanghai University, Shanghai 200444, China; jrebek@scripps.edu yangyu2017@shu.edu.cn.
⁵ Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037.
⁶ Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037.

Abstract

We describe here the effects of metal complexation on the molecular recognition behavior of cavitands with quinoxaline walls. The nitrogen atoms of the quinoxalines are near the upper rim of the vase-like shape and treatment with Pd(II) gave 2:1 metal:cavitand derivatives. Characterization by ¹H, ¹³C NMR spectroscopy, HR ESI-MS, and computations showed that the metals bridged adjacent quinoxaline panels and gave cavitands with C_2v symmetry. Both water-soluble and organic-soluble versions were prepared and their host/guest complexes with alkanes, alcohols, acids, and diols (up to C12) were studied by ¹H NMR spectroscopy. Analysis of the binding behavior indicated that the metals rigidified the walls of the receptive vase conformation and enhanced the binding of hydrophobic and even water-soluble guests, compared to related cavitands reported previously. The results demonstrated that the conformational dynamics of the cavitand were slowed by the coordination of Pd(II) and stabilized the host's complexes.

Keywords: Pd(II) stabilized cavitand; cavitands; metallo cavitand; molecular recognition; water-soluble containers.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.