No abstract

A new aluminum naphthalenedicarboxylate Al(OH)(1,4-NDC) x 2 H2O compound has been synthesized. The crystal structure exhibits a three-dimensional framework composed of infinite chains of corner-sharing octahedral Al(OH)2O4 with 1,4-naphthanedicarboxylate ligands forming two types of channels with squared-shape cross-section. The large channels present a cross-section of 7.7 x 7.7 A(2), while the small channels are about 3.0 x 3.0 A(2). When water molecules are removed, no structural transformation occurs, generating a robust structure with permanent porosity and remarkable thermal stability. 2D (1)H-(13)C heteronuclear correlation NMR measurements, together with the application of Lee-Goldburg homonuclear decoupling, were applied, for the first time, to porous coordination polymers revealing the spatial relationships between the (1)H and (13)C spin-active nuclei of the framework. To demonstrate the open pore structure and the easy accessibility of the nanochannels to the gas phase, highly sensitive hyperpolarized (HP) xenon NMR, under extreme xenon dilution, has been applied. Xenon can diffuse selectively into the large nanochannels, while the small ones show no substantial uptake of xenon due to severe restrictions along the channels that prevent the diffusion. Two-dimensional exchange experiments showed the exchange time to be as short as 15 ms. Through variable-temperature HP (129)Xe NMR experiments we were able to achieve an unprecedented description of the large nanochannel space and surface, a physisorption energy of 10 kJ mol(-1), and the chemical shift value of xenon probing the internal surfaces. The large pore channels are straight, parallel, and independent, allowing one-dimensional anisotropic diffusion of gases and vapors. Their walls are composed of the naphthalene moieties that create an unique environment for selective sorption. These results prompted us to measure the storage capacity toward methanol, acetone, benzene, and carbon dioxide. The selective adsorption of methanol and acetone vs that of water, together with the permanent porosity and high thermal stability, makes this compound a suitable matrix for separation and purification.

The rational construction of efficient bifunctional oxygen electrocatalysts is of immense significance yet challenging for rechargeable metal-air batteries. Herein, this work reports a metal-organic framework derived 2D nitrogendoped carbon nanotubes/graphene hybrid as the efficient bifunctional oxygen electrocatalyst for rechargeable zinc-air batteries. The as-obtained hybrid exhibits excellent catalytic activity and durability for the oxygen electrochemical reactions due to the synergistic effect by the hierarchical structure and heteroatom doping. The assembled rechargeable zinc-air battery achieves a high power density of 253 mW cm −2 and specific capacity of 801 mAh g Zn −1 with excellent cycle stability of over 3000 h at 5 mA cm −2 .Moreover, the flexible solid-state rechargeable zinc-air batteries assembled by this hybrid oxygen electrocatalyst exhibits a high discharge power density of 223 mW cm −2 , which can power 45 light-emitting diodes and charge a cellphone. This work provides valuable insights in designing efficient bifunctional oxygen electrocatalysts for long-life metal-air batteries and related energy conversion technologies.

Cs3Bi2Br9 quantum dots (QDs) with photoluminescence quantum yields (PLQYs) of up to 22% were prepared through the steady binding of octylammonium bromide and oleic acid. Excellent thermal stability and good luminescence properties have been achieved as intrinsic features of the inorganic halide perovskites, as well as the effective passivation of surface trap-states.

Lead-halide perovskites have demonstrated promising performance in the field of photocatalytic hydrogen production. However, the toxicity of lead hinders their application. Herein, an environmentally friendly and lead-free perovskite (CH3NH3)3Bi2I9 was prepared by employing a simple and efficient hydrothermal route. It is found that (CH3NH3)3Bi2I9 exhibits excellent phase stability in hydriodic acid with different concentrations. Under visible light irradiation, it showed satisfactory cycle stability after 70 h of repeated H2 evolution without any degradation or oxidization. After using platinum as a cocatalyst, the photocatalytic rate for H2 evolution is about 169.21 μmol g–1 h–1, resulting in 14 times enhancement compared with the pristine one (about 12.19 μmol g–1 H–1 with 40 mg initial amount) and a solar-to-chemical conversion efficiency of 0.48%. Our research opens new possibilities for the application of lead-free perovskites in the field of photocatalysis.

No abstract

Underwater lighting is important for the exploration of the underwater world in different areas. It is of great significance for developing underwater emitters with high penetrability, high luminous efficiency, good anti‐water stability, and environmental friendliness. Stable lead‐free perovskite luminescent materials, represented by vacancy‐ordered double perovskites, are worthy of research because they can almost meet the above requirements. Here, lead‐free perovskite variant solid solutions with the formula of Cs2Sn1−xTexCl6 are reported. Upon the exchange of Sn/Te ions, strong Jahn–Teller distortion of octahedra occurs in the lattice structure. The combination of Te luminescent center and Jahn–Teller‐like self‐trapped excitons gives this material yellow‐green luminescence with a wavelength of 580 nm and a high photoluminescence quantum yield of 95.4%. Moreover, these solid solutions can withstand the extreme conditions of immersion in water probably due to the formation of amorphous alteration phase. Such good anti‐water stability is also supported by the molecule dynamics simulation result that no reaction occurs on the water/Cs2SnCl6 interface. The high luminous, suitable wavelength, and good anti‐water stability enable the solid solutions suitable for the application for underwater lighting.

The construction of metal±organic framework (MOF) coordination polymers is currently receiving considerable attention owing to their potential properties as functional solid materials, as well as their fascinating framework structures. [1±3] Particularly widely explored have been MOFs with porous chiral structures in which chiral ligands, chiral templates, or chiral functionalization of achiral zeolites are used to perform enantioselective separations and syntheses. [4±7] It is challenging to prepare chiral MOF materials with known chiral topology from an achiral building unit.Learning from nature©s minerals, and utilizing the welldefined coordination geometries of metal centers, some structures of minerals with specific functionality, such as perovsktie, [8] rutile, [9] PtS, [10] and feldspar [11] have been artificially produced by replacing monoatomic anions (O 2À , S 2À ) with polyatomic organic m ligands. The quartz phase, which is chiral, has unique piezoelectricity and thermally sensitive properties and is widely used in resonators and sensors. [12] Although the SiO 2 phase with quartz topology is thermodynamically more stable than cristobalite which has diamond topology, in nature or in artificial materials, known phases which have quartz topology are rare with only one example, a cyano-bridged coordination polymer, reported by Robson and co-workers. [13] Generally, most materials comprising fourconnected tetrahedral (T) units, including MOFs, exist in the diamond topology, [1c,d, 14] rather than the quartz topology, while SiO 2 and GeO 2 are minerals that have both a quartz polymorph and cristobalite with diamond topology. Interestingly, when cristobalite is quenched to room temperature, [15] it is transformed reconstructively to the quartz polymorph.Herein we report the preparation of two quartzlike, chiral, open MOFs, Zn(ISN) 2 ¥2 H 2 O (ISN ¼ isonicotinate), assigned QMOF-1, with the low symmetry of a-quartz and InH(BDC) 2 (BDC ¼ terephthalate), QMOF-2, with the high symmetry of b-quartz. QMOF-1 with a large (~8.6 ä) left-handed channel was successfully synthesized with an asymmetric ISN ligand by using a low-temperature diffusion method (room temperature) similar to the preparation of metal carboxylate [17] . On using a highly distorted complex anion [In(O 2 CR) 4 ] À as the T block, [16] and terephthalate as a linear rod, we could assemble the anion-type b-quartzlike network QMOF-2 with a right-handed channel (~7.8 ä).