Addressed realization of multication complex arrangements in metal-organic frameworks

The preparation of materials with structures composed of multiple metal cations that occupy specific sites is challenging owing to the difficulty of simultaneously addressing the incorporation of different elements at desired precise positions. We report how it is possible to use a metal-organic framework (MOF) built with a rod-shaped inorganic secondary building unit (SBU) to combine multiple metal elements at specific positions in a manner that is controllable at atomic and mesoscopic scales. Through the combination of four different metal elements at judiciously selected molar ratios, 20 MOFs of different compositions and the same topology have been prepared and characterized. The use of diffraction techniques, supported by density functional theory calculations, has led us to determine various possible atomic arrangements of the metal cations within the SBUs. In addition, seven of the compounds combine multiple types of atomic arrangements, which are mesoscopically distributed along the crystals. Given the large diversity and importance of rod-based MOFs, we believe that these findings offer a new general strategy to produce complex materials with required compositions and controllable arrangements of the metal cations for desired applications.Work at Instituto de Ciencia de Materiales de Madrid–Consejo Superior de Investigaciones Científicas (CSIC) has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) Projects MAT2013-45460-R, CTQ2014-61748-EXP, and MAT2016-78465-R. F.G. acknowledges financial support from Fundación General CSIC (Programa ComFuturo) and MINECO (Ramón y Cajal program). Computational time has been provided by the Centre de Supercomputació de Catalunya. This work, developed under the HyMAP project, has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program (grant 648319).We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe