A novel 3D calcium-based metal-organic framework based on a naphthalene diimide chromophore has been synthesized which displays a unique doubly interpenetrated 7-connected net with total point symbol of {3(6)·4(9)·5(6)}. Excellent thermal stability and reversible photochromic properties have been observed in this compound.

Abstract. Nitrous acid (HONO) can strongly affect atmospheric photochemistry in polluted regions through the production of hydroxyl radicals (OHs). In January 2017, a severe pollution episode occurred in the Pearl River Delta (PRD) of China, with maximum hourly PM2.5, ozone, and HONO levels reaching 400 µg m−3, 150 ppb, and 8 ppb, respectively, at a suburban site. The present study investigated the sources and processes generating such high HONO concentrations and the role of HONO chemistry in this severe winter episode. Four recently reported HONO sources were added to the Community Multiscale Air Quality (CMAQ) model, including RH-dependent (relative humidity) and light-enhancing effects on heterogeneous reactions, photolysis of particulate nitrate in the atmosphere, and photolysis of HNO3 and nitrate on surfaces. The revised model reproduced the observed HONO and significantly improved its performance for O3 and PM2.5. The model simulations showed that the heterogeneous generation on surfaces (with RH and light effects) was the largest contributor (72 %) to the predicted HONO concentrations, with the RH-enhancing effects more significant at nighttime and the light-enhancing effects more important in the daytime. The photolysis of total nitrate in the atmosphere and deposited on surfaces was the dominant HONO source during noon and afternoon, contributing above 50 % of the simulated HONO. The HONO photolysis was the dominant contributor to HOx production in this episode. With all HONO sources, the daytime average O3 at the Heshan site was increased by 24 ppb (or 70 %), compared to the simulation results without any HONO sources. Moreover, the simulated mean concentrations of TNO3 (HNO3+ fine particle NO3-) at the Heshan site, which was the key species for this haze formation, increased by about 17 µg m−3 (67 %) due to the HONO chemistry, and the peak enhancement reached 55 µg m−3. This study highlights the key role of HONO chemistry in the formation of winter haze in a subtropical environment.

Functionalizing the redox-active tetrathiafulvalene (TTF) core with groups capable of coordination to metals provides new perspectives on the modulation of architectures and electronic properties of organic−inorganic hybrid materials. With a view to extending this concept, we have now synthesized nickel bis(dithiolene-dibenzoic acid), [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ], which can be considered as the inorganic analogue of the organic tetrathiafulvalene-tetrabenzoic acid (H 4 TTFTB). Likewise, [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ] is a redox-active linker for new functional metal−organic frameworks, as demonstrated here with the synthesis of(2) but is a better electrochemical glucose sensor due to the multiple oxidation−reduction states of the [NiS 4 ] core, which allow glucose to be oxidized to glucolactone by the high oxidation state [NiS 4 ] center. As a non-enzymatic glucose sensor, 1 on Cu foam (CF), 1-CF, was synthesized by a one-step hydrothermal method and exhibited an excellent electrochemical performance. The fabricated 1-CF electrode offers a high sensitivity of 27.9 A M −1 cm −2 , with a wide linear detection range from 2.0 × 10 −6 to 2.0 × 10 −3 M, a low detection limit of 1.0 × 10 −7 M (signal/noise = 3), and satisfactory stability and reproducibility.

Magnetic skyrmions in chiral magnets with the Dzyaloshinskii-Moriya interaction have received intensive attention because of their potential in prospective applications. Here, we theoretically demonstrate that another novel spin texture in chiral magnetsthe chiral strip-domain wall (SDW)-can generate a deep one-dimensional potential well of magnetic origin. We show by micromagnetic simulations that the potential well caused by a SDW can serve as an internal channel to guide spin-wave (SW) propagation, which makes the ultrathin chiral magnet including the SDW become a reconfigurable self-cladding optic-fiber-like magnonic waveguide with a graded refractive index. Furthermore, we design logical NOT and NAND gates based on the statemodulated transmission property of the magnonic waveguide. We also reveal that a SDW can be reliably written into the gate arms using the Slonczewski spin torque. Finally, prospective applications of the observed potential well in other fields are envisioned. This work is expected to open new possibilities for SW guiding and manipulation in ultrathin magnetic nanostructures as well as to help shape the field of beam magnonics.

Understanding magnetism in ferromagnetic metal/semiconductor (FM/SC) heterostructures is important to the development of the new-generation spin field-effect transistor. Here, we report an element-specific X-ray magnetic circular dichroism study of the interfacial magnetic moments for two FM/SC model systems, namely, Co/GaAs and Ni/GaAs, which was enabled using a specially designed FM1/FM2/SC superstructure. We observed a robust room temperature magnetization of the interfacial Co, while that of the interfacial Ni was strongly diminished down to 5 K because of hybridization of the Ni d(eg) and GaAs sp(3) states. The validity of the selected method was confirmed by first-principles calculations, showing only small deviations (<0.02 and <0.07 μB/atom for Co/GaAs and Ni/GaAs, respectively) compared to the real FM/SC interfaces. Our work proved that the electronic structure and magnetic ground state of the interfacial FM2 is not altered when the topmost FM2 is replaced by FM1 and that this model is applicable generally for probing the buried magnetic interfaces in the advanced spintronic materials..

Abstract. Nitrate (NO3-) has become a major component of fine particulate matter (PM2.5) during hazy days in China. However, the role of the heterogeneous reactions of dinitrogen pentoxide (N2O5) in nitrate formation is not well constrained. In January 2017, a severe haze event occurred in the Pearl River Delta (PRD) of southern China during which high levels of PM2.5 (∼400 µg m−3) and O3 (∼160 ppbv) were observed at a semi-rural site (Heshan) in the western PRD. Nitrate concentrations reached 108 µg m−3 (1 h time resolution), and the contribution of nitrate to PM2.5 was nearly 40 %. Concurrent increases in NO3- and ClNO2 (with a maximum value of 8.3 ppbv at a 1 min time resolution) were observed in the first several hours after sunset, indicating an intense N2O5 heterogeneous uptake by aerosols. The formation potential of NO3- via N2O5 heterogeneous reactions was estimated to be between 29.0 and 77.3 µg m−3 in the early hours (2 to 6 h) after sunset based on the measurement data, which could completely explain the measured increase in the NO3- concentration during the same time period. Daytime production of nitric acid from the gas-phase reaction of OH+NO2 was calculated with a chemical box model built using the Master Chemical Mechanism (MCM v3.3.1) and constrained by the measurement data. The integrated nocturnal nitrate formed via N2O5 chemistry was comparable to or even higher than the nitric acid formed during the day. This study confirms that N2O5 heterogeneous chemistry was a significant source of aerosol nitrate during hazy days in southern China.

Heterogeneous reactivity of N 2 O 5 on aerosols is a critical parameter in assessing NO x fate, nitrate production, and particulate chloride activation. Accurate measurement of its uptake coefficient (γ N 2 O 5 ) and representation in air quality models are challenging, especially in the polluted environment. With an in situ aerosol flow-tube system, the γ N 2 O 5 was directly measured on ambient aerosols at two rural sites in northern and southern China. The results were analyzed together with the γ N 2 O 5 derived from previous field studies in China to obtain a holistic picture of N 2 O 5 uptake and the influencing factors under various climatic and chemical conditions. The field-derived or measured γ N 2 O 5 was generally promoted by the aerosol water content and suppressed by particle nitrate. Significant discrepancies were found between the measured γ N 2 O 5 and that estimated from laboratory-determined parameterizations. An observation-based empirical parameterization was derived in the present work, which better reproduced the mean value and variability of the observed γ N 2 O 5 . Incorporating this new parameterization into a regional air quality model (WRF-CMAQ) has improved the simulation of N 2 O 5 , nitrogen oxides, and secondary nitrate in the polluted regions of China.

Inspired by the exciting physical/chemical properties in metal−organic frameworks (MOFs) of the redox-active tetrathiafulvalene (TTF) ligands, nickel bis(dithiolene-dibenzoic acid), [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ], has been designed and developed as an inorganic analogue of the corresponding TTF-type donors (such as tetrathiafulvalene-tetrabenzoate, TTFTB), where a metal site (Ni) replaces the central CC bond. In this work, [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ] and In 3+ have been successfully assembled into a three-dimensional MOF, (Me, with satisfying chemical and thermal stabilities. With the combination of reversible redox activity and unsaturated metal sites originated from [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ], 1 showed a significantly enhanced performance in electrocatalytic CO 2 reduction compared with the isomorphic MOF, (Me 2 NH 2 + )[In III -(TTFTB)]•0.7C 2 H 5 OH•DMF (2, with TTFTB ligand). More importantly, by mimicking the active [NiS 4 ] sites of formate dehydrogenase and CO-dehydrogenase, a prominently higher conversion rate and Faradaic efficiency (FE), with FE HCOO − increasing from 54.7% to 89.6% (at −1.3 V vs RHE, j HCOO − = 36.0 mA cm −2 ), were achieved in 1. Mechanistic investigations further confirm that [NiS 4 ] can serve as a CO 2 binding site and efficient catalytic center. This unprecedented effect of redox-active nickel dithiolene-based MOF catalysts on the performance of electroreduction of CO 2 provides an important strategy for designing stable and efficient crystalline enzyme-mimicking catalysts for the conversion of CO 2 into high-value chemical stocks.