Two-Dimensional Excitonic Metal–Organic Framework: Design, Synthesis, Regulation, and Properties

Abstract

A family of two-dimensional (2D) Zn-based metal–organic frameworks (MOFs) with exitonic emission have been successfully synthesized under hydrothermal conditions. When isophthalic acid ligands with different substitutions are introduced, the crystal structures and fluorescence properties are significantly changed. Hirshfeld surface calculation is used to study the nuances of diverse substitutions during the construction of all of the crystals. The solid fluorescence results indicate that there are obvious two-channel emissions, including intralayer excimers and interlayer trapped excitons, both in 1 and 2 with a double-layer structure and in 3 with a single-layer structure, mainly exhibiting intralayer emission. Furthermore, the fluorescence changes on morphology transformations are explored after mechanical exfoliation consisting of grinding and ultrasonicaation of MOFs 1–3. The regulation and control of crystal structure and morphology can suppress emission based on interlayer excitons, achieving adjustment of the overall emitting color. To the best of our knowledge, this is the first report of 2D bilayer MOFs with dual-channel emissions, which provides a new structural model for synthesizing new exciton materials.

Crystal-to-Crystal Transformation Caused by Cation Exchange and the Difference in Electrochemical Properties of Three Coordination Polymers

“…Therefore, the 3D Hirshfeld surface mapped with d norm and 2D fingerprint plots were analyzed to show the relation between crystal-to-crystal transformation and intermolecular interaction of 1 – 3 . The red areas mean the strong intermolecular interactions in the crystal, the white and blue areas, respectively, expressed as middle and weak intermolecular interactions . As shown in Figure , the red areas in the d norm surface indicated strong hydrogen bonding caused by O···H/H···O and N···H/H···N hydrogen bonds in 1 – 3 .…”

“…The red areas mean the strong intermolecular interactions in the crystal, the white and blue areas, respectively, expressed as middle and weak intermolecular interactions. 41 As shown in Figure 3 Water Adsorption Property. Through the Hirshfeld surface analysis and the structure of 1−3, strong hydrogen bonding interactions in the crystal were found.…”

An Unlimited Color Palette from Perylene Derivative Molecules Dispersed within Hybrids

“…Alternatively, an elegant approach is to protect and disperse the organic fluorophores within a host structure such as metal–organic frameworks (MOFs) or two-dimensional (2D)-layered structures. − As expected, interactions between organic guests and the host modify the degree of stacking and aggregation of the fluorescent molecules. MOFs exhibit stable cages capable of accommodating organic molecules and thus inhibiting the ACQ effect by metal–ligand coordination interactions. − Otherwise, as another inorganic framework of interest, layered double hydroxides (LDHs) received a lot of attention as they can be easily combined with photoactive organic molecules. , Widely tunable in composition and easy to synthesize, LDHs are composed of a positively charged brucite-like layer in the host sheet and negatively intercalated guest anions in the interlayer region as well as water molecules and are generally described with the chemical formula [M 2+ 1– x M 3+ x (OH) 2 ]­(A n – x / n )· m H 2 O (M 2+ and M 3+ : di- and trivalent metal ions, respectively, A n – : guest anions). , The LDH materials have many benefits: (1) rigid layers providing a stable and protective structure, (2) immobilization and dispersion of phosphors in a confined environment, thus preventing the PD molecules from piling up between them, and (3) a good state of dispersion in a polymer medium by surface modification. , Thus, the LDH host structure is an ideal platform to prevent π-stacking between aromatic fluorophores in the solid state and as functional polymer fillers in the concept of manufacturing solid-state white LEDs . In addition, in order to avoid interactions between guest species as much as possible, which causes emission to stop, the content of PD phosphors must be very low.…”

Metal ions Directed Self‐assembly based on Mixed Ligands: From 2D hcb Net to 3D cds Framework

“…[ 10 ] Even a small change in flexibility, length, geometry, or symmetry of organic ligands can result in a remarkable class of materials bearing diverse architectures and functions. [ 11 ] Moreover, construction of CPs with the anticipated structure cannot be controlled due to the complicated synthesis factors as well as the preparation methods, such as solvent, [ 12 ] template, [ 13 ] anions, [ 14 ] reaction temperature, [ 15 ] and pH. [ 16 ] Therefore, in‐depth understanding of the synthesis, structure and performance of CP materials has a high academic value and more research work on exploring the synthesis conditions for CPs are necessary.…”