Photocontrollable J-Aggregation of a Diarylethene–Phthalocyanine Hybrid and Its Aggregation-Stabilized Photochromic Behavior

The photocontrollable J-aggregation of a diarylethene–phthalocyanine hybrid (T-ZnPc) and its aggregation-stabilized photochromic behavior were investigated by various techniques. T-ZnPc initially exhibited slight J-aggregation tendency in solvents such as chloroform and toluene through conformational planarization effect, but formed much stronger J-aggregates upon the illumination of 254 nm UV light. In darkness, the UV-irradiated solutions gradually returned to their initial state. These phenomena can be explained by the pronounced change in molecular planarity accompanying the reversible isomerization of the diarylethene units of T-ZnPc. Besides, we have found that the thermal stability of the closed-ring diarylethene isomers in molecularly dispersed T-ZnPc is much poorer than that in aggregates. As long as the aggregates were broken, they converted to corresponding open-ring form instantly. This study provided an example of fully photocontrollable aggregation of phthalocyanines and paved a new way for improving the stability of the photochromic systems

Fabrication of Hierarchical CaCO₃ Mesoporous Spheres: Particle-Mediated Self-Organization Induced by Biphase Interfaces and SAMs

Highly ordered hierarchical calcium carbonate is an important phase involved in calcification by a wide variety of invertebrate organisms, and its formation is of technological interest in the development of functional materials. In this article, porous CaCO3 hierarchical microspheres with a hedgehoglike appearance have been fabricated on the flexible substrate under mild conditions. There are two points that play important roles in the regular organization of the terminal products: one is the biphase interfaces, which are generated by organic solvent n-hexane and an aqueous saturated solution of Ca(OH)2, and the other is hydroxyl-terminated monolayers assembled on the flexible PET (poly(ethylene terephthalate)) substrate. The SEM images show that novel CaCO3 hierarchical microspheres consist of densely stacked “shuttles” by the oriented self-organization of CaCO3 nanoparticles. The IR and XRD spectra indicate that the as-synthesized products are composed of a calcite phase obtained by an ACC (amorphous calcium carbonate)-to-calcite transformation. In view of the results, a nanoparticle-mediated self-organization process induced by biphase interfaces and SAMs template is proposed for the integration of functional materials and nanodevices

Structural Basis of Specific Binding between Aurora A and TPX2 by Molecular Dynamics Simulations

In the present study, the impacts of G198N and W128F mutations on the recognition between Aurora A and targeting protein of Xenopus kinesin-like protein 2 (TPX2) were investigated using molecular dynamics (MD) simulations, free energy calculations, and free energy decomposition analysis. The predicted binding free energy of the wild-type complex is more favorable than those of three mutants, indicating that both single and double mutations are unfavorable for the Aurora A and TPX2 binding. It is also observed that the mutations alternate the binding pattern between Aurora A and TPX2, especially the downstream of TPX2. An intramolecular hydrogen bond between the atom OD of Asp11TPX2 and the atom HE1 of Trp34TPX2 disappear in three mutants and thus lead to the instability of the secondary structure of TPX2. The combination of different molecular modeling techniques is an efficient way to understand how mutation has impacts on the protein–protein binding and our work gives valuable information for the future design of specific peptide inhibitors for Aurora A

The Role of the Liquid–Liquid Interface in the Synthesis of Nonequilibrium Crystalline Wurtzite ZnS at Room Temperature

In this research, the role that the organic–inorganic liquid interface plays in the synthesis of nonequilibrium crystalline materials is investigated. A hierarchical nanocrystalline film of wurtzite ZnS, the high-temperature stable phase, is successfully prepared at room temperature by an interfacial in situ fabrication process. The organic–inorganic liquid interface constructed by n-hexane and water acts as the reaction zone for the synthesis of ZnS nanocrystalline film. A series of experimental results have proved that the liquid–liquid interface is the key factor for wurtzite ZnS formation at room temperature without any additive. The ZnS film consists of core–shell subunits characterized by ZnS nanoparticles around an organic core. Between the liquid–liquid interface, the core–shell subunits are coupled onto the surface of a SAM-modified substrate by terminal amino groups, so that the ZnS nanocrystalline film is formed by a layer-by-layer mode. This research brings forward a feasible route for synthesizing wurtzite ZnS in one-step process at room temperature and provides some beneficial information for studying the structural kinetics of nonequilibrium crystalline synthesis