Selective Formation of Small and Large Coordination Cages and Their Catalytic Differences.

Self-assembly of CuX2 (X- = BF4-, ClO4-, and CF3SO3-) with a new tridentate 5,5',5″-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(oxy))triisoquinoline (L) gives rise to single-crystal pairs consisting of small and large cages, [X@Cu2X2L4]X and [Cu6X12L8], respectively, via selection of solvents. In particular, the large cage is transformed into a small cage in acetonitrile above 50 °C. A significant difference in heterogeneous catechol oxidation catalysis between the small and large cages is observed. Such notable catechol-oxidation-catalytic effects can be explained by maintenance of the Cu···Cu distance at the catalytic center. This research is a direct systematic example of both cage-size control via solvent selection and the significance of the Cu···Cu distance in catechol oxidation catalysis with copper (Cu).

Crystals of Ni6L12 Ellipsoidal Tubes as Single-Crystal-to-Single-Crystal Adsorption Matrix: Penetrative Study of Self-Assembled Crystals vs Guest-Exchanged Crystals.

Informative similarities/differences between self-assembled and single-crystal-to-single-crystal (SCSC) guest-exchanged crystals based on both the molecular structure and adsorption nature are observed. The self-assembly of Ni(ClO4)2 with a dicyclopentyldi(pyridine-3-yl)silane bidentate ligand (L) in a mixture of toluene and acetonitrile gives rise to purple crystals consisting of double-stranded ellipsoidal tubes, [Ni6(ClO4)4(CH3CN)8L12]·8ClO4·4CH3CN·5C7H8. The coordinated acetonitriles as well as the solvates are removed at 170 °C to transform the purple crystals into blue crystals of [Ni(ClO4)2L2]n that return to the original crystals in the mixture of toluene and acetonitrile. Further, the toluene and acetonitrile solvates of the original crystals are replaced by o-, m-, and p-xylene isomers within 5 min in a SCSC manner. In the present study, SCSC xylene-exchanged crystals were compared with crystals obtained from direct self-assembly in a mixture of each xylene isomer and acetonitrile.

Spontaneous oscillation and fluid-structure interaction of cilia.

The exact mechanism to orchestrate the action of hundreds of dynein motor proteins to generate wave-like ciliary beating remains puzzling and has fascinated many scientists. We present a 3D model of a cilium and the simulation of its beating in a fluid environment. The model cilium obeys a simple geometric constraint that arises naturally from the microscopic structure of a real cilium. This constraint allows us to determine the whole 3D structure at any instant in terms of the configuration of a single space curve. The tensions of active links, which model the dynein motor proteins, follow a postulated dynamical law, and together with the passive elasticity of microtubules, this dynamical law is responsible for the ciliary motions. In particular, our postulated tension dynamics lead to the instability of a symmetrical steady state, in which the cilium is straight and its active links are under equal tensions. The result of this instability is a stable, wave-like, limit cycle oscillation. We have also investigated the fluid-structure interaction of cilia using the immersed boundary (IB) method. In this setting, we see not only coordination within a single cilium but also, coordinated motion, in which multiple cilia in an array organize their beating to pump fluid, in particular by breaking phase synchronization.

Urban Planning and Smart City Decision Management Empowered by Real-Time Data Processing Using Big Data Analytics.

The Internet of Things (IoT), inspired by the tremendous growth of connected heterogeneous devices, has pioneered the notion of smart city. Various components, i.e., smart transportation, smart community, smart healthcare, smart grid, etc. which are integrated within smart city architecture aims to enrich the quality of life (QoL) of urban citizens. However, real-time processing requirements and exponential data growth withhold smart city realization. Therefore, herein we propose a Big Data analytics (BDA)-embedded experimental architecture for smart cities. Two major aspects are served by the BDA-embedded smart city. Firstly, it facilitates exploitation of urban Big Data (UBD) in planning, designing, and maintaining smart cities. Secondly, it occupies BDA to manage and process voluminous UBD to enhance the quality of urban services. Three tiers of the proposed architecture are liable for data aggregation, real-time data management, and service provisioning. Moreover, offline and online data processing tasks are further expedited by integrating data normalizing and data filtering techniques to the proposed work. By analyzing authenticated datasets, we obtained the threshold values required for urban planning and city operation management. Performance metrics in terms of online and offline data processing for the proposed dual-node Hadoop cluster is obtained using aforementioned authentic datasets. Throughput and processing time analysis performed with regard to existing works guarantee the performance superiority of the proposed work. Hence, we can claim the applicability and reliability of implementing proposed BDA-embedded smart city architecture in the real world.

Utilizing a Spiro Core with Acridine- and Phenothiazine-Based New Hole Transporting Materials for Highly Efficient Green Phosphorescent Organic Light-Emitting Diodes.

Two new hole transporting materials, 2,7-bis(9,9-diphenylacridin-10(9H)-yl)-9,9' spirobi[fluorene] (SP1) and 2,7-di(10H-phenothiazin-10-yl)-9,9'-spirobi[fluorene] (SP2), were designed and synthesized by using the Buchwald-Hartwig coupling reaction with a high yield percentage of over 84%. Both of the materials exhibited high glass transition temperatures of over 150 °C. In order to understand the device performances, we have fabricated green phosphorescent organic light-emitting diodes (PhOLEDs) with SP1 and SP2 as hole transporting materials. Both of the materials revealed improved device properties, in particular, the SP2-based device showed excellent power (34.47 lm/W) and current (38.41 cd/A) efficiencies when compare with the 4,4'-bis(N-phenyl-1-naphthylamino)biphenyl (NPB)-based reference device (30.33 lm/W and 32.83 cd/A). The external quantum efficiency (EQE) of SP2 was 13.43%, which was higher than SP1 (13.27%) and the reference material (11.45%) with a similar device structure. The SP2 hole transporting material provides an effective charge transporting path from anode to emission layer, which is explained by the device efficiencies.

Coordinating nature of M6L12 double-stranded macrocycles: co-ligand competition of perchlorate, water, and acetonitrile depending on metal(II) ions.

Self-assembly of M(ClO4)2 (M(II) = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) with dicyclopentyldi(pyridine-3-yl)silane (L) as a donor in a mixture of acetonitrile and toluene produces crystals consisting of M6L12 double-stranded macrocycles. The geometry around the M(II) cations is a typical octahedral arrangement, but the metallamacrocycles' outer axial coordination environment is sensitive to the M(II) cations. The conformation of the unique metallamacrocycles is informatively dependent on the nature of the coordination around the M(II) cations via subtle co-ligand competition among perchlorate anions, water, and acetonitrile. Both the coordinated acetonitriles and the solvate molecules of the crystals are removed at 170 °C, thereby transforming the crystals into new crystals that return to their original form in the mixture of toluene and acetonitrile. Catalytic oxidation of 3,5-di-tert-butylcatechol using [Cu6(ClO4)8(CH3CN)4L12]4ClO4·5C7H8 is much faster than those using the transformed product, [Cu(ClO4)2L2], and a simple mixture of Cu(ClO4)2 + L.

Self-assembly of Ni(II) with a chiral ligand pair vs. mixture of the chiral ligand pair: structural features and recognition ability of Ni2L4 cages.

The self-assembly of NiCl2 with a chiral bidentate ligand pair, (1R,2S)-(+)- and (1S,2R)-(-)-1-(nicotinamido)-2,3-dihydro-1H-inden-2-yl nicotinate (r,s-L and s,r-L) in a mixture of ethanol and dioxane, gives rise to stable crystals consisting of [2Cl@Ni2Cl2(s,r-L)4(H2O)2]·4C4H8O2·EtOH and [2Cl@Ni2Cl2(r,s-L)4(H2O)2]·4C4H8O2·EtOH chiral cages, respectively, with two encapsulated chloride anions in the cavities. The most interesting feature is that the self-assembly of NiCl2 with the mixture of r,s-L and s,r-L (1 : 1-1 : 4) produces crystals of thermodynamically stable achiral cages, [2Cl·2H2O@Ni2Cl2(s,r-L)2(r,s-L)2(H2O)2]·7C4H8O2, in the molar ratio range. Furthermore, the [2Cl@Ni2Cl2(s,r-L)4(H2O)2]·4C4H8O2·EtOH and [2Cl@Ni2Cl2(r,s-L)4(H2O)2]·4C4H8O2·EtOH chiral crystals can recognize the pairs of L-,D-tryptophan and L-,D-cysteine via cyclic voltammetry (CV) signals, in contrast to the [2Cl·2H2O@Ni2Cl2(s,r-L)2(r,s-L)2(H2O)2]·7C4H8O2 achiral crystal.

M(II) effect on encapsulation of guests into a series of M3L2 chiral cages: enantio-recognition.

Self-assembly of M(ClO4)2 (M2+ = Ni2+, Cu2+, and Zn2+) with (1S,1'S,1''S,2R,2'R,2''R)-(benzenetricarbonyltris(azanediyl))tris(2,3-dihydro-1H-indene-2,1-diyl) trinicotinate (s,r-L) and the corresponding enantiomer (r,s-L) as a pair of chiral tridentate donors gives rise to the chiral cage pairs [M3(s,r- and r,s-L)2](ClO4)6. For the two pairs of [(Me2CO)(H2O)@M3(r,-s and s,r-L)2](ClO4)6 (M2+ = Ni2+ and Zn2+), the inner cavity is occupied by both an acetone and a single water molecule, whereas for the copper(II) pair of [Me2CO@Cu3(r,s- and s,r-L)2](ClO4)6 under the same conditions, the cavity is filled by only one acetone molecule. Thus, the encapsulation of guest molecules into the cages during self-assembly shows significant metal(II) ion effects. These chiral cages are effective for the enantio-recognition of chiral (S)-2-butanol and (R)-2-butanol via the shifts of the electrochemical oxidation potentials obtained by the linear sweep voltammetry (LSV) technique, density functional theory (DFT) calculations, and the chiral 2-butanol adsorption in the single-crystal-to-single-crystal (SCSC) mode.

Formation Process of SiF6@Cu2L4 Chiral Cage Pairs in a Glass Vessel: Catechol Oxidation Catalysis and Chiral Recognition.

Self-assembly of CuX2 (X- = BF4-, PF6-, and SbF6-) with a pair of chiral bidentate ligands, (1R,2S)-(+)- and (1S,2R)-(-)-1-(nicotinamido)-2,3-dihydro-1H-inden-2-yl-nicotinate (r,s-L or s,r-L), in a mixture solvent including ethanol in a glass vessel gives rise to SiF62--encapsulated Cu2L4 chiral cage products. The SiF62- anion from the reaction of X- with SiO2 of the glass-vessel surface acts as a cage template or cage bridge. One of the products, [SiF6@Cu2(SiF6)(s,r-L)4]·3CHCl3·4EtOH, is one of the most effective heterogeneous catalysts for the oxidation of 3,5-di-tert-butylcatechol. Furthermore, an l-DOPA/d-DOPA pair is recognizable by the cyclic voltammetry (CV) signals of its combination with chiral cages [SiF6@Cu2(BF4)2(s,r- or r,s-L)4]·4CHCl3·2EtOH pair and [SiF6@Cu2(SiF6)(s,r- or r,s-L)4]·3CHCl3·4EtOH pair.

Structural properties of [Cu(II)3L6] cages: bridged polyatomic anion effects on unprecedented efficiency of heterogeneous catechol oxidation.

Self-assembly of CuX2 (X- = BF4-, ClO4-, PF6-, and SbF6-) with a bidentate ethylmethylbis(3-pyridine)silane ligand (L) in the presence of additional polyatomic anions (X' = SiF62- and PF6-) gives rise to single crystals consisting of the X'@[Cu(II)3L6] cage motif. These cages exist as discrete or anion-bridged 3D networks depending on outside anions. The anion-bridged 3D networks interpenetrate in a four-fold fashion, and show, to our best knowledge, the most effective heterogeneous catalysis in 3,5-di-tert-butylcatechol oxidation reaction within 20 min at room temperature. Surprisingly, the heterogeneous catalysis is more effective than its corresponding homogeneous catalysis. Such notable catalytic effects can be explained by the maintenance of 3D inter-cage Cu⋯Cu distance as a catalytic center.