2 research outputs found
Single-Crystalline Organic–Inorganic Layered Cobalt Hydroxide Nanofibers: Facile Synthesis, Characterization, and Reversible Water-Induced Structural Conversion
New pink organic–inorganic
layered cobalt hydroxide nanofibers
intercalated with benzoate ions [CoÂ(OH)Â(C<sub>6</sub>H<sub>5</sub>COO)·H<sub>2</sub>O] have been synthesized by using cobalt nitrate and sodium benzoate as
reactants in water with no addition of organic solvent or surfactant.
The high-purity nanofibers are single-crystalline in nature and very
uniform in size with a diameter of about 100 nm and variable lengths
over a wide range from 200 μm down to 2 μm by simply adjusting
reactant concentrations. The as-synthesized products are well-characterized
by scanning electron microscope (SEM), transmission electron microscopy
(TEM), high-resolution transmission electron microscopy (HRTEM), fast
Fourier transforms (FFT), X-ray diffraction (XRD), energy dispersive
X-ray spectra (EDX), X-ray photoelectron spectra (XPS), elemental
analysis (EA), Fourier transform infrared (FT-IR), thermogravimetric
analysis (TGA), and UV–vis diffuse reflectance spectra (UV–vis).
Our results demonstrate that the structure consists of octahedral
cobalt layers and the benzoate anions, which are arranged in a bilayer
due to the π–π stacking of small aromatics. The
carboxylate groups of benzoate anions are coordinated to Co<sup>II</sup> ions in a strong bridging mode, which is the driving force for the
anisotropic growth of nanofibers. When NaOH is added during the synthesis,
green irregular shaped platelets are obtained, in which the carboxylate
groups of benzoate anions are coordinated to the Co<sup>II</sup> ions
in a unidentate fashion. Interestingly, the nanofibers exhibit a reversible
transformation of the coordination geometry of the Co<sup>II</sup> ions between octahedral and pseudotetrahedral with a concomitant
color change between pink and blue, which involves the loss and reuptake
of unusual weakly coordinated water molecules without destroying the
structure. This work offers a facile, cost-effective, and green strategy
to rationally design and synthesize functional nanomaterials for future
applications in catalysis, magnetism, gas storage or separation, and
sensing technology
Physicochemical Properties of Air and Water Stable Rhenium Ionic Liquids
Air and water stable ionic liquids (ILs) based on catalytic
functional
metal rhenium, [C<sub><i>n</i></sub>mim]Â[ReO<sub>4</sub>]Â(<i>n</i> = 2,4,5,6)Â(1-alkyl-3-methylimidazolium perrhenate),
are designed and synthesized. Their density and surface tension are
measured in the temperature range of 293.15–343.15 ± 0.05
K. Some physical-chemical properties of the ILs have been calculated
or estimated by the empirical methods. The ion parachor is put forward
and calculated by two extrathermodynamic assumptions. According to
the interstice model, the thermal expansion coefficient of ILs [C<sub><i>n</i></sub>mim]Â[ReO<sub>4</sub>], α, are calculated
and in comparison with experimental values, their magnitude order
is in good agreement