Rational design of two-dimensional dysprosium-nitronyl nitroxide MOF with photo-thermal-electric conversion and photo-driven water evaporation.

Lanthanide-radical (Ln-rad) metal-organic frameworks (MOFs) possess exceptional prospects in utilization of renewable energy. However, to date, most of reported Ln-nitronyl nitroxide compounds exhibit discrete or low-dimensional structures. The rational preparation of Ln-rad MOFs still faces significant challenges. Furthermore, they are subject to unruly and highly reactive nature of radicals, not to mention the investigation of energy conversion. Herein, utilizing modifiable terminal functional group of nitronyl nitroxide, we expanded a one-dimensional chain into a novel two-dimensional (2D) DyIII-rad MOF {[Dy(hfac)3]3(NITPhO-3Py)2·2CH2Cl2}n (2D-Dy (1)) (NITPhO-3Py = 2-(3-pyridinyloxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide). Profiting the increase in spatial dimensions and enhanced light absorption property of 2D-Dy (1), 2D-Dy (1) acts as excellent photothermal conversion material to attain water evaporation efficiency of 70.6%. Furthermore, by integrating with the thermoelectric module, 2D-Dy (1) can utilize temperature difference along the thermoelectric module to achieve electric power generation, and successfully drive the electromagnet. In Ln-nitronyl nitroxide system, 2D-Dy (1) is applied in photo-thermo-electric conversion for the first time. This work not only achieves rational design of lanthanide-nitronyl nitroxide MOF, but also establishes a fascinating functional molecular platform for photo-thermo-electric conversion and water evaporation.