A Monomeric Stannabenzene: Synthesis,Structure, and Electronic Properties

A tin‐containing benzene, stannabenzene, was synthesized and isolated as a monomeric form. The X‐ray crystallographic analysis revealed the planar structure of the stannabenzene ring and unsaturated Sn?C and C?C bonds without bond alternation. Low‐field shifted NMR signals and negative nuclear‐independent chemical shifts (NICS) values are in agreement with the features of aromatic compounds. The narrow HOMO–LUMO gap of stannabenzene has been revealed by UV/Vis spectroscopy and electrochemistry.     

A Monomeric Stannabenzene: Synthesis,Structure, and Electronic Properties

A tin‐containing benzene, stannabenzene, was synthesized and isolated as a monomeric form. The X‐ray crystallographic analysis revealed the planar structure of the stannabenzene ring and unsaturated Sn?C and C?C bonds without bond alternation. Low‐field shifted NMR signals and negative nuclear‐independent chemical shifts (NICS) values are in agreement with the features of aromatic compounds. The narrow HOMO–LUMO gap of stannabenzene has been revealed by UV/Vis spectroscopy and electrochemistry.     

Fundamental diagram in traffic flow of mixed vehicles on multi-lane highway

We study the fundamental diagram for traffic flow of vehicular mixture on a multi-lane highway. We present the car-following model of multi-lane traffic in which slow and fast vehicles flow with changing lanes. We investigate the traffic states of the vehicular mixture under the periodic boundary. Two values of the current appear at a density and two current curves are obtained. Vehicles move with changing lanes in the traffic state of high current, while vehicles move without changing lanes in the traffic state of low current. They depend on the density, the fraction of slow vehicles, and the initial condition. In the high-current curve, the jamming transition between the free flow and the jammed state occurs at a low density. The fundamental diagrams (current-density diagrams) are shown for the single-lane, two-lane, three-lane, and four-lane traffics.     

Mechanochromic Delayed Fluorescence Switching in Propeller-Shaped Carbazole–Isophthalonitrile Luminogens with Stimuli-Responsive Intramolecular Charge-Transfer Excited States

Herein, the universal design of high-efficiency stimuli-responsive luminous materials endowed with mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) functions is reported. The origin of the unique stimuli-triggered TADF switching for a series of carbazole–isophthalonitrile-based donor–acceptor (D–A) luminogens is demonstrated based on systematic photophysical and X-ray analysis, coupled with theoretical calculations. It was revealed that a tiny alteration of the intramolecular D–A twisting in the excited-state structures governed by the solid morphologies is responsible for this dynamic TADF switching behavior. This concept is applicable to the fabrication of bicolor emissive organic light-emitting diodes using a single TADF emitter.     

Pyrene分子(小片石墨晶体)的电子传导特性

利用量子理论中基于Green函数的tight-binding方法,对pyrene分子的电子传导和电子流分布进行了理论研究。在考虑到界面耦合和Hopping积分的情况下,得出了电子透射谱和流分布的模拟结果。结果显示透射与电子的能量紧密相关;谱的振荡特征是能级量子化的结果;流分布有着特定的方向,并且在每一个原子点上符合Kirchhoff量子流守恒定律。另外还发现了桥接pyrene分子的正负能开关特性。     

Three-dimensional porous coordination polymer functionalized with amide groups based on tridentate ligand: selective sorption and catalysis

To create a functionalized porous compound, amide group is used in porous framework to produce attractive interactions with guest molecules. To avoid hydrogen-bond formation between these amide groups our strategy was to build a three-dimensional (3D) coordination network using a tridentate amide ligand as the three-connector part. From Cd(NO3)2.4H2O and a three-connector ligand with amide groups a 3D porous coordination polymer (PCP) based on octahedral Cd(II) centers, {[Cd(4-btapa)2(NO3)2].6H2O.2DMF}n (1a), was obtained (4-btapa = 1,3,5-benzene tricarboxylic acid tris[N-(4-pyridyl)amide]). The amide groups, which act as guest interaction sites, occur on the surfaces of channels with dimensions of 4.7 x 7.3 A2. X-ray powder diffraction measurements showed that the desolvated compound (1b) selectively includes guests with a concurrent flexible structural (amorphous-to-crystalline) transformation. The highly ordered amide groups in the channels play an important role in the interaction with the guest molecules, which was confirmed by thermogravimetric analysis, adsorption/desorption measurements, and X-ray crystallography. We also performed a Knoevenagel condensation reaction catalyzed by 1a to demonstrate its selective heterogeneous base catalytic properties, which depend on the sizes of the reactants. The solid catalyst 1a maintains its crystalline framework after the reaction and is easily recycled.     

Enantiomeric Separation of Underivatized Aliphatic β-Amino Alcohols by Ligand-exchange Chromatography using N-n-Dodecyl-(1R,2S)-norephedrine as a Coating Reagent for Reversed-phase Column

Underivatized aliphatic β-amino alcohols with a primary or secondary alcohol moiety were separated into enantiomers by high performance liquid chromatography using octadecylsilanized silica coated with N-n-dodecyl-(1R,2S)-norephedrine as the stationary phase and an aqueous solution containing copper(II) and barbital as the mobile phase.