Flexible Alkali–Halogen Bonding in Two Dimensional Alkali-Metal Organic Frameworks

Abstract

On-surface fabrication of two-dimensional (2D) metal organic frameworks (MOFs) has been continuously attracting attentions for years. However, the synthesis of 2D MOFs with large-amplitude flexibility was rarely carried out since the bonding configurations in the coordination nodes are typically highly directional. Here we demonstrate that single alkali ions, which are fully isotropic in ionic bonding, can act as pivot joints for constructing tunable 2D MOFs by bonding to dihalogen groups in organic molecules. We take 2,3,6,7,10,11-hexabromotriphenylene, a 3-fold polycyclic molecule with three ortho-dibromo groups, and sodium (Na) atoms as a model system and successfully construct Na-based MOFs on Au(111) surface. The deflection angle of the Na coordination nodes is variable in an unprecedentedly large range between ±36°that allows the construction of multiple 2D MOF architectures. Such a flexible alkali−halogen bonding may provide a unique toolbox for designing and constructing more tunable MOFs by choosing various alkali atoms and halogen moieties.

Benchmarking various types of partial atomic charges for classical all-atom simulations of metal–organic frameworks

“…We also excluded MOFs that have alkali ions substituting metal centers on the frameworks. While alkali ions can form halogen bonding in 2D MOFs 48 and direct the formation of pore structures in anionic MOFs, 49 no evidence of six- or eight-fold coordination between ligands and alkali ions has been reported in 3D MOFs to the best of our knowledge. Second, we only utilized the crystallographic information from primitive cells of selected MOFs when calculating the six types of partial charges.…”

Deprotonation-Induced Phase Transitions in the Self-Assembled Structure of Prochiral Carboxyl Derivatives

“…The self-assembly of molecules on well-defined substrates creates great opportunities for designing and actualizing novel two-dimensional (2D) nanostructures. − Various noncovalent interactions, including hydrogen bonding, − ionic hydrogen bonding, , halogen bonding, − van der Waals interactions, π–π stacking, , and coordinate bonds, − are the driving forces that enable the formation of ordered nanostructures. In particular, double hydrogen bonds between carboxyl groups, which are stronger than single hydrogen bonds, are widely used in the construction of stable supramolecular structures. − The self-assembly of various tricarboxylic acid molecules with inflexible structures has been studied, which often shows the formation of hexagonal networks. − However, conformationally flexible carboxylic acid molecules, which have a 2D chirality when limited to solid surfaces, have rarely been investigated.…”

Celebrating the 10th Anniversary of the Youth Innovation Promotion Association, Chinese Academy of Sciences: Emerging Young Scientists in Physical Chemistry

“…The Letter by Wang et al 16 reveals the anisotropic d−d transition in rutile TiO 2 and describes a systematic energy shift of electronic structure due to symmetry broken at the surface. Apart from these mechanism studies, this Virtual Special Issue also contains recent advances on synthesis, assembly, and applications of advanced materials, such as Ag 2 Se thermoelectric material, 17 2D metal−organic frameworks (MOFs), 18 Published: January 20, 2022 25 porous aromatic frameworks (PAFs), 26 a SiO x -based memristor, 27 a graphitelike carbon nitride nanotube, 28 α-C:H film, 29 light-harvesting molecular wires, 30 a bioresponsive zeolitic imidazolate framework (ZIF) system, 31 an M-PM 2−x -H 2 -based aqueous Zn battery, 32 and a MnO x @PAA@HKUST-1-DSF@BSA-based theranostic nanoagent. 33 The theoretical scientists in YIPA have always tried to explore high-throughput calculations to understand and design the functionality of advanced materials.…”

“…reveals the anisotropic d–d transition in rutile TiO 2 and describes a systematic energy shift of electronic structure due to symmetry broken at the surface. Apart from these mechanism studies, this Virtual Special Issue also contains recent advances on synthesis, assembly, and applications of advanced materials, such as Ag 2 Se thermoelectric material, 2D metal–organic frameworks (MOFs), ZnGa 2 O 4 :Cr 3+ nanoparticles, colloidal CdSe-based nanoplatelets, Cs 4 PbI 6 –CsPbI 3 :Yb perovskite nanocomposites, Ti 3+ ion-doped CsPbCl 3 perovskite nanocrystals, carbon quantum dots, colloidal photonic crystals, a K 2 Zn 3 (SO 4 )­(HSO 4 ) 2 F 4 -based nonlinear optical crystal, porous aromatic frameworks (PAFs), a SiO x -based memristor, a graphite-like carbon nitride nanotube, α-C:H film, light-harvesting molecular wires, a bioresponsive zeolitic imidazolate framework (ZIF) system, an M-PM 2– x -H 2 -based aqueous Zn battery, and a MnO x @PAA@HKUST-1-DSF@BSA-based theranostic nanoagent …”