Molecular Dynamics Studies of Aromatic Guests in Three Isostructural Inclusion Compounds with Molecular Boron–Nitrogen Hosts

Abstract

The dynamics of three guests: benzene (ben), naphthalene (nap), and xylene (xyl) included in the isostructural cavities of tetrameric [(2fbe) 2 (bpy)⊃guest] 4 cages were examined using single-crystal X-ray diffraction, thermogravimetric analysis, variable-temperature solid-state 2 H NMR spectroscopy, and molecular dynamics simulations. The inclusion compounds were selected from a series of boron−nitrogen host adducts assembled in a 2:1 stoichiometric ratio from the catechol ester of 2,4difluorophenylboronic acid (2fbe) and 4,4′-bipyridine (bpy) in the presence of aromatic guests. The dynamic characterization studies revealed that ben is highly mobile with fast in-plane jumps around the C 6 -axis above T = 150 K, with a calculated activation energy, E a , of 4.9 kJ mol −1 . Surprisingly, the larger guest nap experiences 180°jumps above 296 K. On the contrary, xyl guests can only experience 120°in-plane jumps at temperatures close to the decomposition point because the methyl groups act as effective stoppers.

Dative B←N bonds based crystalline organic framework with permanent porosity for acetylene storage and separation

“…[30][31][32] The utilization of dative B)N bonds in structural supramolecular chemistry has become increasingly popular in recent years. [33][34][35] Since Kay Severin pioneered the synthesis of the rst crystalline organic framework based on the B)N bonds (BNOF) by using triboronate esters and bipyridyl ligands in 2011, 36 other 1D and 2D crystalline BNOFs have been designed and synthesized by combining polytopic N-donor ligands with polyboronate esters. [37][38][39] It is now known that the robustness of B)N bonds is signicantly dependent upon the steric and electronic properties of the interacting components, 33,40 as these properties can prevent the sensitive boronate ester moieties from hydrolyzing.…”

Self-Healing B ← N-Based Hydrogen-Bonded Organic Framework for Exclusive Recognition and Separation of Toluene from Methyl-Cyclohexane

“…Dative B ← N bonds are widely acknowledged for their role in constructing supramolecular structures. − Although B ← N bonds can be stronger than hydrogen bonds, their capacity to create permanent porosity in frameworks has only been confirmed recently. − We refer to such materials as B ← N frameworks (BNF). , In previous studies, we observed significant electron transfer between N- and B-containing monomers during the formation of B ← N bonds. This process endows the N-containing monomers with obvious electron-deficient features, thereby creating specific binding sites for aromatic compounds, − such as Tol. , However, the separation of Tol from mixtures has not been achieved in B ← N materials to date. The crystalline and stable BNFs are very rarely obtained especially under the condition of mixed organic solvents, which make it arduous to build up frameworks for highly selective recognition and separation of aromatic hydrocarbons from mixtures.…”

Multidynamic Crystalline Molecular Rotors Comprising an N‐Heterocyclic Carbene Binuclear Au(I) Complex Bearing Multiple Rotators

“…The design of molecular rotation in crystalline media has attracted much interest not only in the field of molecular machines but also in solid-state functional materials, because the rotation-induced molecular geometry alteration can provide an avenue for switching the physical properties of solid compounds. [1][2][3][4][5][6][7][8] To construct the crystalline materials, known as crystalline molecular rotors, gyroscope-like molecular rotors, [2][3][4][9][10][11] dumbbell-shaped molecules, [2][3][12][13][14][15][16][17] and porous solid-state materials such as metal-organic frameworks (MOFs) [5][6][7][8][18][19][20][21][22][23] have been utilized. The general blueprint of this design is based on the combination of a rotator moiety with a bulky and rigid domain as a stator that is used to construct the ordered frame as well as the local space that can undergoes molecular rotation.…”