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A unique morphology for bent-core liquid crystals forming the B4 phase has been found for a class of tris-biphenyl bent-core liquid crystal molecules with a single chiral side chain in the longer para-side of the molecule. Unlike the parent molecules with two chiral side chains or a chiral side chain in the shorter meta-side, which form helical nano- or microfilament B4 phases, the two derivatives described here form heliconical-layered nanocylinders composed of up to 10 coaxial heliconical layers, which can split or merge, braid, and self-assemble into a variety of modes including feather- or herringbone-type structures, concentric rings, or hollow nest-like superstructures. These multi-level hierarchical self-assembled structures, rivaling muscle fibers, display blue structural color and show immense structural and morphological complexity.

Polymorphism is a remarkable concept in chemistry, materials science, computer science, and biology. Whether it is the ability of a material to exist in two or more crystal structures, a single interface connecting to two different entities, or alternative phenotypes of an organism, polymorphism determines function and properties. In materials science, polymorphism can be found in an impressively wide range of materials, including crystalline materials, minerals, metals, alloys, and polymers. Here we report on polymorphism in a liquid crystal. A bent-core liquid crystal with a single chiral side chain forms two structurally and morphologically significantly different liquid crystal phases solely depending on the cooling rate from the isotropic liquid state. On slow cooling, the thermodynamically more stable oblique columnar phase forms, and on rapid cooling, a not heretofore reported helical microfilament phase. Since structure determines function and properties, the structural color for these phases also differs.

The remarkable ability of certain molecules with a bent molecular shape to form hierarchically self-assembled helical building blocks with negative Gaussian or cylindrical curvature featuring in-layer hexatic ordering– so-called B4 phases – has quickly transformed these molecules into desirable building blocks for a variety of potential applications in optics, energy harvesting, and metamaterials. We here demonstrate that these building blocks, helical nanofilaments, helical microfilaments, and heliconical-layered nanocylinders, can to some degree be predictably blended. Supported by scanning as well as transmission electron microscopy and variable angle x-ray scattering data, the three bent-core compounds, each forming exactly one of these B4 morphologies, in binary mixtures at a 1:1 molar ratio, form either the third missing, or one of the two but with opposite handedness, or a random mixture of the two selected morphologies with larger overall dimensions. Furthermore, for two of the mixtures the a priori predicted handedness of the chiral filaments was experimentally confirmed. The third mixture with a priori predicted antagonistic handedness of the initial morphologies forms a combination of the two, one apparently achiral and the other one with opposite handedness. [ABSTRACT FROM AUTHOR]

Polymorphism is a remarkable concept in chemistry, materials science, computer science, and biology. Whether it is the ability of a material to exist in two or more crystal structures, a single interface connecting to two different entities, or alternative phenotypes of an organism, polymorphism determines function and properties. In materials science, polymorphism can be found in an impressively wide range of materials, including crystalline materials, minerals, metals, alloys, and polymers. Here we report on polymorphism in a liquid crystal. A bent-core liquid crystal with a single chiral side chain forms two structurally and morphologically significantly different liquid crystal phases solely depending on the cooling rate from the isotropic liquid state. On slow cooling, the thermodynamically more stable oblique columnar phase forms, and on rapid cooling, a not heretofore reported helical microfilament phase. Since structure determines function and properties, the structural color for these phases also differs. [ABSTRACT FROM AUTHOR]

In this study, the synthesis and characterization of copper nano/microparticles in the presence of (2,2′,2″,2″′-(ethane-1,2-diylbis(azanetriyl))tetraacetohydrazide) as a capping and reducing agent under hydrothermal conditions for use in biological conditions were investigated. The effects of reductant ligand/copper ion, concentration ratios, reaction temperatures, and reaction time on the various morphologies of copper nano/microparticles were studied. The obtained particles have been characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrum analysis (EDAX), and zeta potential analysis. Further, the formation of particles with different morphologies was confirmed. The biological and antifungal effects of these selected particles were compared with those of the Bordeaux mixture. Experiments were conducted onAlternaria alternata, Alternaria solani, andFusarium expansumas three types of phytopathogenic fungi andPenicilliumsas a non-phytopathogenic fungus. The results obtained showed that not only were the nano/microparticles more effective than Bordeaux mixture in killing phytopathogenic fungi, but also these particles did not have a fungicidal effect on the non-phytopathogenic fungus,Penicillium, which is an advantage of the obtained nano/microparticles. [ABSTRACT FROM PUBLISHER]

The synthesis and characterization of magnetite nanoparticles in the presence of 2,2′,2″,2″′-(ethane-1,2-diylbis(azanetriyl)) tetraacetohydrazide as reducing agent in hydrothermal reaction were performed. Fe3O4nanoparticles with a diameter range 15–21 nm were achieved. The formation of pure Fe3O4nanoparticles was confirmed by XRD patterns and electron dispersive X-ray (EDX) analysis. The morphology of particles was characterized by scanning electron microscopy (SEM). The effects of reactants ratio, reducing agent and precursor, reaction temperature, and process time are described. It was found that the different reaction conditions such as ligand concentration, reaction temperature, and process time had little effect on the size of the synthesized nanoparticles. [ABSTRACT FROM PUBLISHER]

Abstract: We describe here a complex precursor hydrothermal route to prepare uniform Cu2O microsphere, spherical composite of Cu2O/Cu nanocrystals with controlled size and composition and a wide range of novel copper microstructures using {[Cyclohexyl(phosphonomethyl)amino]methyl}phosphonic acid (dP) as both the complexing and reducing agent. It is noteworthy that changing the characteristic of initially formed Cu2+-aminodiphosphonate complex precursor via manipulating synthetic parameters was crucial to the growth of the final product. Time order of growth process at pH=9 has been revealed: (1) aggregation of Cu2O nanoparticles to form spherical microstructure, (2) recrystallization of Cu2O nanoparticles parallel to reductive transformation from Cu2O to Cu to produce spherical Cu2O/Cu microstructure consisting of larger nanoparticles and (3) increasing the nanoparticle size of Cu2O/Cu microstructure as the content of Cu phase increases. At pH=14, only pure Cu microcrystals of different shapes were obtained. The effects of concentration and molar ratio of starting materials, reaction time and temperature on the growth process and morphology of copper microcrystals were investigated. Finally, a possible growth mechanism is proposed. The obtained samples have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier Transform infrared spectroscopy. [Copyright &y& Elsevier]