Could π-aromaticity cross an unsaturated system to a fully saturated one?

The classification of π-/σ-aromaticity depends on the electrons with the dominating contributions.Traditionally,π-andσ-aromaticity are used to describe the unsaturated and saturated systems,respectively.Thus,it is rarely reported that π-aromaticity is dominated in a saturated system.Here we demonstrate that π-aromaticity could be dominating in several fully saturated four-membered rings(4MRs),supported by various aromaticity indices including ΔBL,NICS,EDDB,MCI,and Ad NDP.The origin of suchπ-aromaticity in saturated rings could be attributed to an introduction of two additional electrons into the π-type LUMO of the parent neutral species.Our findings represent a novel approach to achieve π-aromaticity into a fully saturated system which has traditionally been dominated by σ-aromaticity.

Nanostructured Columns from Self-assemblyof Complementary Molecular Components

Nanostructured columns with a length about several tens of micrometer and a diameter of about 80 nm were obtained by molecular recognition directed self-assembly of a pair of comple- mentary molecular components, 4-amino-2 , 6-didodecylamino-1 , 3, 5-triazine(M) and 5- (4-dode- cyloxybenzylidene )-(1H, 3H)-2, 4, 6-pyrimidinetrione (B) in chloroform. In this system, with positive cooperativity, π-aromatic stacking and van der Waals interactions as well as hydrogen bonds cause the formation of the nanocolumns.

Manipulation of π-aromatic conjugation in two-dimensional Sn-organic materials for efficient lithium storage

Sn-based materials are promising candidates for lithium storage but suffer generally from huge volume change during the(de)lithiation processes.Sn-organic materials with monodispersed Sn centers surrounded by lithium active ligands can alleviate the volume change of anode materials based on reversible(de)lithiation processes.However,the structural factors governing the kinetics of lithium storage and utilization efficiency of active sites are not well understood to date.Herein,we report three two-dimensional Sn-organic materials with enhanced lithium storage performance by manipulation ofπ-aromatic conjugation of the ligands.The increasingπ-aromatic conjugation plays a key role in promoting efficient lithium storage,and the volume expansion during the(de)lithiation reaction is suppressed in these Sn-organic materials.This work reveals that theπ-aromatic conjugation of the ligand is crucial for improving the kinetics of lithium storage and the utilization of active sites in metalorganic materials with minimised volume expansion.

Kinetic model for hydroisomerization reaction of C_(8)-aromatics

Based on the reported reaction networks,a novel six-component hydroisomerization reaction net-work with a new lumped species including C_(8)-naphthenes and C_(8)-paraffins is proposed and a kinetic model for a commercial unit is also developed.An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke forma-tion on the catalyst surface during the long-term opera-tion.The Runge-Kutta method is used to solve the ordinary differential equations of the model.The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential vari-able metric optimization method(BFGS).The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predic-tions and the plant observations.