Water-Soluble Metallo-Supramolecular Nanoreactors for Mediating Visible-Light-Promoted Cross-Dehydrogenative Coupling Reactions.

Han, Xin; Guo, Chenxing; Xu, Chen; Shi, Linlin; Liu, Binghui; Zhang, Zhe; Bai, Qixia; Song, Bo et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

Water-soluble metallo-supramolecular cages with well-defined nanosized cavities have a wide range of functions and applications. Herein, we design and synthesize two series of metallo-supramolecular octahedral cages based on the self-assembly of two congeneric truxene-derived tripyridyl ligands modified with two polyethylene glycol (PEG) chains, i.e., monodispersed tetraethylene glycol (TEG) and polydispersed PEG-1000, with four divalent transition metals (i.e., Pd, Cu, Ni, and Zn). The resulting monodispersed cages <b>C1</b>-<b>C4</b> are fully characterized by electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (NMR) spectroscopy, and single-crystal X-ray diffraction. The polydispersed cages <b>C5</b>-<b>C8</b> display good water solubilities and can act as nanoreactors to mediate visible-light-promoted C(sp<sup>3</sup>)-C(sp<sup>2</sup>) cross-dehydrogenative coupling reactions in an aqueous phase. In particular, the most robust Pd(II)-linked water-soluble polydispersed nanoreactor <b>C5</b> is characterized by ESI-MS and capable of mediating the reactions with the highest efficiencies. Detailed host-guest binding studies in conjunction with control studies suggest that these cages could encapsulate the substrates simultaneously inside its hydrophobic cavity while interacting with the photosensitizer (i.e., eosin Y).