Highly selective synthesis of interlocked carbazole-based cages and their applications in photothermal seawater desalination.

Lu, Ming-Yu; Yang, Jian-Xin; Xu, Ya-Ning; Chai, Yin-Hang; Wan, Xiao-Qian; Zhao, Ying; Aznarez, Francisco; Tian, Dan et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The design and assembly of interlocked supramolecular cages is of interest due to their exquisite topological configuration and excellent performance in a variety of applications. We introduce two carbazole-based ligands L1 and L2, they combine with four distinct half-sandwich rhodium building blocks to form three molecular-tweezer-like compounds, three interlocked cages, tetranuclear macrocycle, and hexanuclear cage. Stacking interactions between carbazole groups facilitate the formation of interlocked structures. Single-crystal X-ray diffraction, Nuclear Magnetic Resonance Spectroscopy and Electrospray Ionization Mass Spectrometry determine their structures. The compounds 5(OTf)<sub>12</sub>, 6(OTf)<sub>12</sub> and 7(OTf)<sub>12</sub> exhibit broad-band absorption from Ultraviolet-Visible Spectroscopy to the Near-Infrared regions and remarkable photothermal conversion. They are incorporated into membranes 5'(OTf)<sub>12</sub>, 6'(OTf)<sub>12</sub>, and 7'(OTf)<sub>12</sub>, whose applications in solar energy-driven steam generation are studied. Evaporation rates of 0.77, 1.52, and 1.37 kg·m<sup>-2</sup>·h<sup>-1</sup> are recorded for 5'(OTf)<sub>12</sub>, 6'(OTf)<sub>12</sub>, and 7'(OTf)<sub>12</sub>, respectively, indicating their suitability to collect fresh water from desalination and wastewater treatment.