Gnanasekaran Karthikeyan, Vailonis Kristina M, Jenkins David M, Gianneschi Nathan C
Department of Chemistry, Department of Materials Science & Engineering, Department of Biomedical Engineering, Department of Pharmacology, International Institute for Nanotechnology, Simpson Querrey Institute, and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States.
Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States.
ACS Nano. 2020 Jul 28;14(7):8735-8743. doi: 10.1021/acsnano.0c03209. Epub 2020 Jun 24.
Metal-organic nanotubes (MONTs) are highly ordered one-dimensional crystalline porous frameworks. Despite being nanomaterials, virtually all studies of MONTs rely on characterization of the bulk crystalline material (micron-sized) by single-crystal X-ray diffraction. For MONTs to achieve their raison d'être as tunable one-dimensional nanomaterials, individual tubes or small finite bundles of tubes must be synthesized and characterized. Therefore, to directly observe their formation under a variety of reaction conditions in solution, we employ liquid-cell transmission electron microscopy (LCTEM), which allows the early stages of MONT assembly to be monitored in real time. Notably, changing the metal-to-ligand ratio alters the local concentrations of reactant monomers, resulting in multiple nucleation and growth pathways and diverse morphologies at the nanoscale. These various initial seeds grow to form the same nanocrystalline needle phase. This approach of employing LCTEM to study these nanomaterials is analogous to monitoring typical homogeneous solution phase reactions by NMR for controlled nanomaterial formation.
金属有机纳米管（MONTs）是高度有序的一维晶体多孔框架。尽管是纳米材料，但几乎所有关于MONTs的研究都依赖于通过单晶X射线衍射对块状晶体材料（微米尺寸）进行表征。为了使MONTs作为可调控的一维纳米材料发挥其存在的意义，必须合成并表征单个纳米管或小的有限管束。因此，为了在溶液中的各种反应条件下直接观察它们的形成过程，我们采用了液体池透射电子显微镜（LCTEM），它能够实时监测MONT组装的早期阶段。值得注意的是，改变金属与配体的比例会改变反应物单体的局部浓度，导致多种成核和生长途径以及纳米尺度上的多样形态。这些不同的初始晶种生长形成相同的纳米晶针状相。这种利用LCTEM研究这些纳米材料的方法类似于通过核磁共振监测典型的均相溶液相反应以实现可控的纳米材料形成。
