Design and synthesis of air-stable and easily tailored high-performance single-molecule magnets (SMMs) are of great significance toward the implementation of SMMs in molecular-based magneto-electronic devices. Here, by introducing electron-withdrawing fluorinated substituents on equatorial ligand, two chiral Dy­(III) macrocyclic complexes, RRRR-Dy-D 6hF12 (1) and SSSS-Dy-D 6hF12 (2), with a record anisotropy barrier exceeding 1800 K and the longest relaxation time approaching 2500 s at 2.0 K for all known air-stable SMMs, were obtained. The nearly perfect axiality of the ground Kramers doublet (KD) enables the open hysteresis loops up to 20 K in the magnetically diluted sample. It is notable that they are structurally rigid with high thermal stability and the apical ligand can be tailored to carry proper surface-binding groups. This finding not only improves the magnetic properties for air-stable SMMs but also provides a new avenue for deposition of SMMs on surfaces.

We present a non-fullerene electron acceptor bearing a fused 10-heterocyclic ring with a narrow band gap, which achieved a power conversion efficiency of 6.5% when paired with PTB7-Th.

The structures, ionization potentials (IPs), electron affinities (EAs), and HOMO-LUMO gaps (∆ H-L) of the oligomers are studied by the density functional theory with B3LYP functional. The lowest excitation energies (Egs) and the maximal absorption wavelength λabs of oligomers of polyfluorene (PF) and poly(2,7-fluorene-alt-co-5,7-dihydrodibenz[c,e]oxepin) (PFDBO) are studied employing the timedependent density functional theory (TD-DFT) and ZINDO. Band gaps and effective conjugation lengths of the corresponding polymers were obtained by extrapolating HOMO-LUMO gaps and the lowest excitation energies to infinite chain length. The IPs, EAs, and λ abs of the polymers were also obtained by extrapolating those of the oligomers to the inverse chain length equal to zero (1/n ) 0). For PFDBO, IPs and EAs are higher and the band gap is larger than those of PF's from the extrapolation. The outcome shows that the dramatically twisted structure of PFDBO in the seven-membered ring results in the decreased conjugation in the chain. These cause both the maximal absorption and emission wavelengths of PFDBO blue shift compared with PF.

Atomically precise metal clusters have attracted increasing interest owing to their unique size-dependent properties; however, little has been known about the effect of size on the catalytic properties of metal clusters at the single-cluster level. Here, by real-time monitoring with single-molecule fluorescence microscopy the size-dependent catalytic process of individual Au clusters at single-turnover resolution, we study the size-dependent catalytic behaviors of gold (Au) clusters at the single-cluster level, and then observe the strong size effect on the catalytic properties of individual Au clusters, in both catalytic product formation and dissociation processes. Surprisingly, indicated by both experiments and density functional theory (DFT) calculations, due to such a unique size effect, besides observing the different product dissociation behaviors on different-sized Au clusters, we also observe that small Au clusters [i.e., Au15(MPA)13; here, MPA denotes 3-mercaptopropionic acid] catalyze the product formation through a competitive Langmuir–Hinshelwood mechanism, while those relatively larger Au clusters [e.g., Au18(MPA)14 and Au25(MPA)18] or nanoparticles catalyze the same process through a noncompetitive Langmuir–Hinshelwood mechanism. Such a size effect on the nanocatalysis could be attributed intrinsically to the size-dependent electronic structure of Au clusters. Further analysis of dynamic activity fluctuation of Au clusters reveals more different catalytic properties between Au clusters and traditional Au nanoparticles due to their different size-dependent structures.

A heterogeneous cloud system, for example, a Hadoop 2.6.0 platform, provides distributed but cohesive services with rich features on large‐scale management, reliability, and error tolerance. As big data processing is concerned, newly built cloud clusters meet the challenges of performance optimization focusing on faster task execution and more efficient usage of computing resources. Presently proposed approaches concentrate on temporal improvement, that is, shortening MapReduce time, but seldom focus on storage occupation; however, unbalanced cloud storage strategies could exhaust those nodes with heavy MapReduce cycles and further challenge the security and stability of the entire cluster. In this paper, an adaptive method is presented aiming at spatial–temporal efficiency in a heterogeneous cloud environment. A prediction model based on an optimized Kernel‐based Extreme Learning Machine algorithm is proposed for faster forecast of job execution duration and space occupation, which consequently facilitates the process of task scheduling through a multi‐objective algorithm called time and space optimized NSGA‐II (TS‐NSGA‐II). Experiment results have shown that compared with the original load‐balancing scheme, our approach can save approximate 47–55 s averagely on each task execution. Simultaneously, 1.254‰ of differences on hard disk occupation were made among all scheduled reducers, which achieves 26.6% improvement over the original scheme. Copyright © 2016 John Wiley & Sons, Ltd.

Light is not the only stimulus that can induce linear-to-cyclic isomerization of donor-acceptor Stenhouse adducts (DASAs). Here we demonstrate the water-induced linear-to-cyclic isomerization of DASAs. The mechanism of the water-induced linear-to-cyclic isomerization of DASAs is investigated by density functional theory (DFT) calculations. Water molecules coordinate with DASAs and stabilize the intermediates and cyclic isomers, which favors cyclization thermodynamically. Moreover, the linear-to-cyclic isomerization is reversible. Heating removes the coordinated H 2 O molecules, which further triggers cyclic-to-linear isomerization. DASAs have been applied in information hiding/displaying and color switching under water vapor and heating control.

Density functional theory (DFT) is applied to analyze ground-and excited-state properties of the Re(I) halide bipyridine complex ReCl(CO) 3 (bpy) (1) and the related complexes ReCl(CO) 3 (5,5′-dibromo-bpy) (2), ReCl-(CO) 3 (4,4′-dimethyl-bpy) (3), and ReCl(CO) 3 (4,4′-dimethylformyl-bpy) (4) (where bpy ) 2,2′bipyridine). The electronic properties of the neutral molecules, in addition to the positive and negative ions, are studied using the B3LYP functional. Excited singlet and triplet states are examined using time-dependent DFT (TDDFT). The low-lying excited-state geometries are optimized at the ab initio configuration interaction singlets (CIS) level. As shown, the occupied orbitals involved in the transitions have a significant mixture of the metal Re and the group Cl, by the amount of metal 5d character which varies from 30 to 65%. The lowest unoccupied molecular orbital (LUMO) is a π* orbital of the ligand bpy for the series of molecules. The TDDFT result indicates that the absorption maxima are at relatively high energy and are mainly assigned to bpy-based ππ* transitions with somewhat metal-to-ligand charge transfer (MLCT) [d(Re) f π*(bpy)] and ligand-to-ligand charge transfer (LLCT) [p(Cl) f π*(bpy)] except for complex 3, in which this band is mainly assigned to mixed MLCT/LLCT, and overlaps bpy ππ* character. All the low-lying transitions are categorized as mixed MLCT/LLCT. The absorption bands are blue shifted when substituted by an electron-releasing group (-CH 3 ), and they are red shifted when substituted by an electron-withdrawing group (-Br or -COOCH 3 ). The luminescence of all complexes is assigned as a triplet metal/chlorine to bpy charge transfer (MLCT/LLCT).

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