Site selective 5f electronic correlations inβ-uranium

We investigate the electronic structure ofβ-uranium,which has five nonequivalent atomic sites in its unit cell,by means of the density functional theory plus Hubbard-U correction with U from linear response calculation.It is found that the 5f electronic correlations inβ-uranium are moderate.More interestingly,their strengths are site selective,depending on the local atomic environment of the present uranium atom.As a consequence,the occupation matrices and partial 5f density of states ofβ-uranium manifest site dependence.In addition,the complicate experimental structure ofβ-uranium could be well reproduced within this theoretical framework.

Bulking Up the Bay-Position Substituents Enables Enhanced Selectivity of C_(s)‑Symmetric Boron Subphthalocyanine−Subnaphthalocyanine Hybrids

The precise synthesis of subporphyrinoid hybrids withπ-expanded topologies and unique material properties plays a promising role in the design of functional macrocycles.Easy,selective,and controllable routes to boron subphthalocyanine−subnaphthalocyanine hybrids,Bsub(Pc_(3‑p)-Nc_(p))s,are desirable for this purpose yet synthetically challenging due to random mixtures of C_(s-),C_(3v-),and,in some cases,C_(1)-symmetric compounds that form during traditional statistical mixed cyclotrimerizations.Herein,we addressed this issue by developing a sterically driven mixed cyclotrimerization with enhanced selectivity for the targeted C_(s)-symmetric hybrid and complete suppression of sterically crowded macrocyclic byproducts.This process,coupled with a rationally designed precursor bearing bulky phenyl substituents,enabled the synthesis and characterization of bay-position phenylated Ph_(2)-(R_(p))_(8)Bsub(Pc_(2)-Nc_(1))hybrids with halogens(Rp=Cl or F)in their peripheral isoindole rings.Reaction selectivity ranged between 59 and 72%with remarkable yields,significantly higher than that of conventional mixed cyclotrimerizations.These findings were augmented by theoretical calculations on precursor Lewis basicity as guiding principles into hybrid macrocycle formation.Additionally,the incorporation of unfused phenyl groups and halogen atoms into the hybrid framework resulted in fine-tuned optical,structural,electronic,and electrochemical properties.This straightforward approach achieved improved selectivity and controlled narrowing of the product distribution,affording the efficient synthesis of structurally sophisticated Bsub(Pc_(2)-Nc_(1))hybrids.This then expands the library of 3-dimensionalπ-extended macrocycles for use in a range of applications,such as in optoelectronic devices with precisely tailored optical properties.

Emerging in-plane anisotropic two-dimensional materials

Black phosphorus(BP)is a rapidly up and coming star in two-dimensional(2D)materials.The unique characteristic of BP is its in-plane anisotropy.This characteristic of BP ignites a new type of 2D materials that have low-symmetry structures and in-plane anisotropic properties.On this basis,they offer richer and more unique low-dimensional physics compared to isotropic 2D materials,thus providing a fertile ground for novel applications including electronics,optoelectronics,molecular detection,thermoelectric,piezoelectric,and ferroelectric with respect to in-plane anisotropy.This article reviews the recent advance in characterization and applications of in-plane anisotropic 2D materials.

Recent advances in anisotropic two-dimensional materials and device applications

Two-dimensional(2D)materials,such as transition metal dichalcogenides(TMDs),black phosphorus(BP),MXene and borophene,have aroused extensive attention since the discovery of graphene in 2004.They have wide range of applications in many research fields,such as optoelectronic devices,energy storage,catalysis,owing to their striking physical and chemical properties.Among them,anisotropic 2D material is one kind of 2D materials that possess different properties along different directions caused by the intrinsic anisotropic atoms5 arrangement of the 2D materials,mainly including BP,borophene,low-symmetry TMDs(ReSe2 and ReSa)and group IV monochalcogenides(SnS,SnSe,GeS,and GeSe).Recently,a series of new devices has been fabricated based on these anisotropic 2D materials.In this review,we start from a brief introduction of the classifications,crystal structures,preparation techniques,stability,as well as the strategy to discriminate the anisotropic characteristics of 2D materials.Then,the recent advanced applications including electronic devices,optoelectronic devices,thermoelectric devices and nanomechanical devices based on the anisotropic 2D materials both in experiment and theory have been summarized.Finally,the current challenges and prospects in device designs,integration,mechanical analysis,and micro-/nano-fabrication techniques related to anisotropic 2D materials have been discussed.This review is aimed to give a generalized knowledge of anisotropic 2D materials and their current devices applications,and thus inspiring the exploration and development of other kinds of new anisotropic 2D materials and various novel device applications.

Design of Metal-Organic Assemblies via Shape Complementarity and Conformational Constraints in Dual Curvature Ligands

While common in biological systems,building blocks with low symmetry and flexibility pose numerous problems for synthetic self-assembly,such as the formation of isomers of assemblies that are difficult to distinguish and purify.In this work,three aromatic amide-based ligands(L1–L3)with a central 1,8-diazatriptycene core were designed and used for selfassembly with Pd^(2+).While hundreds of stereoisomers based on the conformational flexibility around the amides and the unsymmetrical nonplanar structure of the core are possible upon coordination with the metal,the constraints designed into the ligands direct the self-assembly toward only a single Pd_(2)L_(4)cage(L1)or Pd_(4)L_(8)double-walled metallomacrocycle(L2)structure,even in mixtures of the ligands.This structural approach and the modularity of the ligand synthesis affords ready access to deep cavitands with endohedral functionalization(L3).These results highlight the potential of this new design strategy and open the door to selectively functionalized cavity-based architectures for numerous applications.