Achieving Morphological Control over Lamellar Manganese Metal-Organic Framework through Modulated Bi-Phase Growth

A modulated bi-phase synthesis towards large-scale manganese 1,4-benzenedicarboxylate (MnBDC) MOFs with a precise control over their morphology (bulk vs. layered) is presented. Metal precursors and organic ligands are separated to reduce the kinetic reaction rates for better control over the crystallization process. Based on scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy studies, the continuous ligand supply along with the presence of pyridine capping agent are highly effective in promoting the layer-by-layer growth and achieving large crystal sizes. Once layered MnBDC is stabilized, topotactic intercalation chemistry was used to demonstrate the feasibility of bromine intercalation on these layered materials. Bromine intercalation is possible between the MOFs layers for the first time. Bromine intercalation causes colossal reduction in layered MnBDC band gap while it has no observable effect on bulk MOFs.