Polycrystalline fibers of porous coordination polymers (PCPs) were synthesized from free-standing alumina nanofiber materials by a coordination replication process. The diameter and morphology of fibrous PCP architectures were controlled by the concentration of aluminum salts and the pH of the reaction solution of replication, respectively. CO 2 adsorption measurement proved the presence of hierarchical porosity composed of both micropores and mesopores in PCP fibers.Porous coordination polymers (PCPs) or metalorganic frameworks (MOFs), crystalline coordination frameworks with an intrinsic microporosity, are an intriguing class of porous materials for applications in storage and separation of molecules. 1 The improvement of porous properties has relied on the modification of pore surface by introducing chemical functionality or on the control of pore size and shape by replacing linkers with the same geometry.2 Apart from these molecular-scale modifications, structuring of PCPs on a mesoscopic or macroscopic scale, in which PCP nanocrystals as building blocks are assembled into higher-order architectures, has very recently emerged as an orthogonal approach to molecular modification for the improvement of material performance.3 Using template approaches or microfabrication technologies, it was found that assemblages of PCP crystals, for instance, zero-dimensional (0D) hollow spheres, 4 two-dimensional (2D) patterns, 5 or threedimensionally (3D) extended architectures 6 demonstrated characteristic properties depending on material morphologies.
3Among higher-order architectures, one-dimensional (1D) nanofiber morphology remains largely unexplored, except for a very limited number of reports.7 This is simply because of the limitation of the fabrication protocol; PCPs are constructed via an assembly of metal ions and organic links so that the confinement of the coordination reaction into one dimension is quite challenging. Therefore, a new method to spatially "program" coordination reactions 8 is a prerequisite for structuring PCPs in a desired dimension.In this study, we synthesized 1D fibrous macroscopic architectures of PCP crystals by the direct conversion of alumina to aluminum-based PCPs while maintaining macroscopic fibrous morphology. We recently proposed this method, so-called "coordination replication," 9 for the fabrication of 2D honeycomb patterns, 3D extended architectures, 9 or hybrid gold nanorods PCP coreshell composites. 10 In this manuscript, we describe the conversion of 1D alumina nanofibers to aluminum-based PCP nanofibers, [Al(OH)(L)] n (L = 1,4-naphthalanedicarboxylate (ndc) or 1,4-benzenedicarboxylate (bdc)), as shown in Figure 1.This strategy relies on the use of sacrificial metal oxides both as a solid-state metal source and structure-directing agents. Since metal oxides can easily be shaped into desired architectures using a solgel process or the thermal oxidation of corresponding metal salts, these methods offer powerful means to produce various designed PCP-based structures. Here, electro...