Fluorinated ester additive to regulate nucleation behavior and interfacial chemistry of room temperature sodium-sulfur batteries.

Room temperature sodium-sulfur (RT Na-S) batteries are considered as advanced energy storage technology due to their low cost and high theoretical energy density. However, challenges such as the growth of sodium dendrite and dissolution of sodium polysulfides significantly hinder the electrochemical performance. Herein, we developed a propylene carbonate (PC)-based electrolyte with Methyl 2-Fluoroisobutyrate (MFB) as an additive.

Encapsulation of sulfur in MoS-modified metal-organic framework-derived N, O-codoped carbon host for sodium-sulfur batteries.

Room-temperature sodium-sulfur batteries (RT Na-S) are promising energy storage systems with high energy densities and low costs. Nevertheless, drawbacks, including the limited cycle life and sluggish redox kinetics of sodium polysulfides, hinder their implementation. Herein, a heterostructure of MoS nanosheets coated on a metal-organic framework (MOF)-derived N, O-codoped flower-like carbon matrix (NOC) was designed as a sulfur host for advanced RT Na-S batteries.

Polyvinylpyrrolidone regulated synthesis of mesoporous titanium niobium oxide as high-performance anode for lithium-ion batteries.

TiNbO (TNO) as a promising candidate anode for lithium-ion batteries (LIBs) shows obvious advantages in terms of specific capacity and safety, but which undergoes the intrinsic poor electrical and ionic conductivity. Herein, we propose a simple synthesis strategy of mesoporous TNO via a polymeric surfactant-mediated evaporation-induced sol-gel method, using polyvinylpyrrolidone (PVP) with different molecular weights (average Mw: 10000/58000/1300000) as the regulating agent, which greatly affects the lithium storage performance of the as-prepared TNO. The optimized TNO (i.

A MoSe/N-doped hollow carbon sphere host for rechargeable Na-Se batteries.

Sodium-selenium (Na-Se) batteries are promising alternatives to lithium-ion batteries for energy storage systems owing to their high energy density and natural abundance of Na resources. However, their drawbacks of low Se loading, dissolution of intermediate sodium polyselenides in the electrolyte and volumetric expansion of Se impede their real applications. To address these issues, herein, we report a multifunctional Se host with MoSe2 nanosheets coupled with nitrogen-doped porous carbon hollow spheres for the first time.

MOF-Derived CoS/N-Doped Carbon Composite to Induce Short-Chain Sulfur Molecule Generation for Enhanced Sodium-Sulfur Battery Performance.

Dissolution of intermediate sodium polysulfides (NaS; 4≤≤8) is a crucial obstacle for the development of room-temperature sodium-sulfur (Na-S) batteries. One promising strategy to avoid this issue is to load short-chain sulfur (S), which could prohibit the generation of soluble polysulfides during the sodiation process. Herein, unlike in the previous reported cases where short-chain sulfur was stored by confinement within a small-pore-size (≤0.

Hierarchical CoS/N-Doped Carbon@MoS Nanosheets with Enhanced Sodium Storage Performance.

We introduce a hierarchical nanostructure of CoS/N-doped carbon@MoS comprising two transition-metal sulfides CoS and MoS, with enhanced sodium storage performance in sodium-ion batteries. A micron-sized Co metal-organic framework (MOF) is transformed into a CoS/N-doped carbon composite, followed by a solvothermal growth of MoS nanosheets on the surface. The resulting composite material offers several specific advantages for sodium storage: (i) accelerated sodium-ion diffusion kinetics due to its heterogeneous interface; (ii) shortened ion diffusion path and exposed active sites for sodium storage due to its hierarchical nanosheet architecture; and (iii) homogeneous nitrogen doping of the MOF-derived carbon, which is beneficial for electronic conductivity.

Selenizing CoMoO nanoparticles within electrospun carbon nanofibers towards enhanced sodium storage performance.

Transition metal oxides/selenides as anodes for sodium-ion batteries (SIBs) suffer from the insufficient conductivity and large volumetric expansion, which leads to the poor electrochemical performance. To address these issues, we herein demonstrate a facile selenization method to enhance the sodium storage capability of CoMoO nanoparticles which are encapsulated into the electrospun carbon nanofibers (CMO@carbon for short). The partially and fully selenized CoMoO within carbon nanofibers (denote as CMOS@carbon and CMS@carbon, respectively) can be readily obtained by controlling the annealing temperature (at 400 and 600 °C, correspondingly).

Broad-Band Photodetectors Based on Copper Indium Diselenide Quantum Dots in a Methylammonium Lead Iodide Perovskite Matrix.

Low-temperature solution-processed methylammonium lead iodide (MAPbI) crystalline films have shown outstanding performance in optoelectronic devices. However, their high dark current and high noise equivalent power prevent their application in broad-band photodetectors. Here, we applied a facile solution-based antisolvent strategy to fabricate a hybrid structure of CuInSe quantum dots (CISe QDs) embedded into a MAPbI matrix, which not only enhances the photodetector responsivity, showing a large on/off ratio of 10 at 2 V bias compared with the bare perovskite films, but also significantly (for over 7 days) improves the device stability, with hydrophobic ligands on the CuInSe QDs acting as a barrier against the uptake of environmental moisture.

Metal-Organic Framework Derived CoS Wrapped with Nitrogen-Doped Carbon for Enhanced Lithium/Sodium Storage Performance.

Transition metal sulfides are attractive electrode materials for both lithium-ion (LIBs) and sodium-ion batteries (SIBs). Starting from micron-sized Co(IPC)·HO (IPC: 4-(imidazole-1-yl) phthalic acid) and polydopamine as the metal-organic framework (MOF) precursor and carbon source, respectively, we produced a CoS/C/C composite constituting CoS nanoparticles decorated with N-doped carbon layers and subjected to sulfurization. N-doped carbon layers provided a robust network for the CoS nanoparticles, enhancing the structural integrity and electronic conductivity of the resulting CoS/C/C composite, which exhibited electrochemical performance superior to most existing CoS composites, and was one of the best among all MOF derived CoS anodes for LIBs and SIBs.

Bottom-up construction of POM-based macrostructures: coordination assembled paddle-wheel macroclusters and their vesicle-like supramolecular aggregation in solution.

A bottom-up approach to obtain nanoclusters and large, uniform vesicle-like structures containing organic functionalized hexamolybdates in solution state were developed. Hexamolybdate functionalized carboxylic acid coordinated with two copper ions to form paddle-wheel tetrapolyoxometalate clusters with the features of macro-ions, which can spontaneously assemble into large, stable blackberry-type structures in suitable solvents, completing a hierarchical organization from small POM molecules to nanoscale complexes and then to supramolecular structures.

Synthesis and assembly of a difunctional core POM cluster with two appended POM cluster caps.

A series of nanorod-like organic-inorganic hybrids based on hexamolybdate and Anderson-type heteropolyoxomolybdates has been prepared using the well-developed DCC protocol. The present work opens a way to flexibly introduce two different functional groups to a hexamolybdate ion and explore thoroughly the whole family of organoimido derivatives for fabricating novel molecular nanostructures with tunable properties.

The chemistry of organoimido derivatives of polyoxometalates.

The chemistry of organoimido derivatives of polyoxometalates (POMs) has received increasing interest. In recent decades, a great development of the synthetic chemistry of organoimido derivatives of POMs using different imido-releasing reagents has taken place, particularly the novel DCC-dehydrating protocol to prepare organoimido derivatives of POMs was developed recently by us and co-workers. Organoimido substituted POMs as valuable building blocks can construct novel nanostructured organic-inorganic hybrid molecular materials in well-developed common organic synthesis methods, such as Pd-catalyzed carbon-carbon coupling and esterification.

χ-Octamolybdate [Mo(V)4Mo(VI)4O24](4-): an unusual small polyoxometalate in partially reduced form from nonaqueous solvent reduction.

The first mixed-valent octamolybdate anion [Mo(V)(4)Mo(VI)(4)O(24)](4-), termed χ-octamolybdate due to its shape, was obtained by partial reduction of α-(Bu(4)N)(4)-[Mo(8)O(26)] in dry acetonitrile. Single-crystal X-ray structure analysis revealed that the anion includes an unusual Mo(V)(4)O(8) cubane-like cluster core, whose four side faces are capped by four MoO(4) units to form a crosslike cluster. X-ray photoelectron spectroscopy (XPS) and bond valence sum (BVS) calculations were carried out to validate the presence of mixed-valent Mo centers.

Polyoxometalatocyclophanes: controlled assembly of polyoxometalate-based chiral metallamacrocycles from achiral building blocks.

The first polyoxometalatocyclophanes have been synthesized by the covalent linkage of a hexamolybdate cluster and bisarylimido ligands containing flexible chains. These metallamacrocycles are chiral, and some of them can undergo spontaneous resolution. The work provides a new protocol for preparing chiral polyoxometalates (POMs) and chiral metallamacrocycles from achiral building blocks by fastening both ends of a flexible chain onto an achiral POM to remove the symmetric center and mirror.

Rh(II)-catalyzed reaction of alpha-diazocarbonyl compounds bearing beta-trichloroacetylamino substituent: C-H insertion versus 1,2-H shift.

The Rh(II)-carbene reaction is dramatically affected by the neighboring substituents. If the neighboring substituent is an OH group, a1,2-H shift is the exclusive pathway. If it is an OAc group, a 1,2-acetoxy migration is observed.

Nanoscale chiral rod-like molecular triads assembled from achiral polyoxometalates.

The assembly of two achiral POMs of Lindqvist and Anderson through strong covalent linkages, using bifunctional TRIS with a rotatable C-N single bond, gives two nanoscale rod-like chiral molecular triads with C(2) symmetry, the chirality of which were confirmed by the single crystal X-ray diffraction analyses and solid CD spectroscopy measurements. The enantiopure crystals of these compounds have been obtained by spontaneous resolution upon crystallization in the absence of any chiral source. The present work opens a way to make chiral nanostructures from achiral polyoxoanions, which may have potential applications in asymmetric catalysis, NLO, and ferroelectric materials.

From 0D dimer to 2D network-supramolecular assembly of organic derivatized polyoxometalates with remote hydroxyl via hydrogen bonding.

A series of remote hydroxyl functionalized organoimido derivatives of hexamolybdate, (Bu(4)N)(2)[Mo(6)O(18)(Cres)] (1) (Cres = 4-amino-m-cresol), (Bu(4)N)(2)[Mo(6)O(17)(Cres)(2)] x H(2)O (2), (Bu(4)N)(2)[Mo(6)O(18)(Phen)] x i-PrOH (Phen = p-aminophenol)(3), (Bu(4)N)(2)[Mo(6)O(18)(Phen)] x EtOH (4), (Bu(4)N)(2)[Mo(6)O(17)(Phen)(2)] (5), (Bu(4)N)(2)[Mo(6)O(18)(Naph)] (Naph = 5-amino-1-napheynyl) (6), and (Bu(4)N)(2)[Mo(6)O(18)(Chex)] x 1.5 H(2)O (Chex = trans-4-aminocyclohexanol) (7) were synthesized and characterized by single crystal X-ray diffraction, FT-IR spectra, UV-vis spectra, elemental analysis, (1)H NMR, and cyclic voltammetry. X-ray structural study reveals that intermolecular and intramolecular hydrogen bonding plays an important role in their supramolecular assembly; it is found that (i) bridged oxo ligands of hexamolybdate cluster are more inclined to form hydrogen bonds as acceptors than terminal oxo ligands in this system; (ii) small solvent molecules with hydrogen bonding donor and acceptor, such as water, i-PrOH, and EtOH, usually act as hydrogen bonding bridge in their supramolecular assembly; (iii) hydrogen bonding has an important influence on their anion conformation besides cell packing; (iv) the hydrogen bonding supramolecular assembly of compounds 1-7 demonstrate an interesting change from dimer (3), to 1D infinite single chain (4), to 1D infinite double chain (2), and to 2D network (1, 5, 6, and 7) owing to the alteration of the grafting organic ligand, the substituted number, and the crystallized solvent molecule.

Iron(III) coordination induced novel 18-metallacrown-6 complex: esterification and isolation of the ligand.

The trianionic heptadentate ligand, (Z)-3-(salicylhydrazinocarbonyl) propenoic acid ((Z)-H(4)shcpa) (1), has been synthesized in good yield and reacted with FeCl(3).6H(2)O, to produce the complex [Fe(III)(6) (C(12)H(9)N(2)O(5))(6)(H(2)O)(2)(CH(3)OH)(4)] x 6CH(3)OH (2). The complex has been characterized by single-crystal X-ray diffraction.

1,2-migration in rhodium(II) carbene transfer reaction: remarkable steric effect on migratory aptitude.

A series of diazo carbonyl compounds bearing different substituents have been prepared in order to investigate the steric effect in 1,2-migration reaction of rhodium(II) carbene. Through the investigation on the diazo decomposition of these compounds with Rh2(OAc)4, it was found that the steric effect could dramatically influence the migratory aptitude. In many cases, the steric effect could override the inherent electronic effect of the substituent.

1,2-vinyl and 1,2-acetylenyl migration in Rh(II) carbene reaction: remarkable bystander effect.

A series of beta-(trichloroacetyl)amino alpha-diazo carbonyl compounds have been synthesized, and their Rh(II)-catalyzed reaction was investigated. 1,2-Migration was the predominant reaction pathway, and the migratory aptitude was found to be dramatically affected by the beta-substituents. The 1,2-vinyl and 1,2-acetylenyl group migration occurs preferentially in the presence of beta-hydrogen in Rh(2)(OAc)(4)-catalyzed reaction of beta-(trichloroacetyl)amino alpha-diazo carbonyl compounds.