Crystals2014, 4(4), 509-515; doi:10.3390/cryst4040509 - published 11 December 2014 Show/Hide Abstract
Abstract: Three azolo[b]1,3,4-thiadiazinium bromides were prepared from the respective N-amino-N'-methylazolethiones and phenacyl bromide, and their crystal structures were determined. 6-Phenyl-1-methylimidazo[2,1-b]1,3,4-thiadiazinium bromide (1) crystallized as methanol solvate (P21/n), 6-phenyl-1-methyl-1,2,4-triazolo[3,4-b]1,3,4-thiadiazinium bromide (2) as hemi-ethanol solvate (P21/n), and 6-phenyl-1-methyl-1,2,4-triazolo[3,2-b]1,3,4-thiadiazinium bromide (3) solvent-free (P21/c). Interionic contacts were identified.
Crystals2014, 4(4), 498-508; doi:10.3390/cryst4040498 - published 4 December 2014 Show/Hide Abstract
Abstract: A one-dimensional photonic crystal (PhC) with termination by a metal film—a plasmonic photonic-crystal slab—has been theoretically analyzed for its optical response at a variation of the dielectric permittivity of an analyte and at a condition simulating the molecular binding event. Visualization of the Bloch surface wave resonance (SWR) was done with the aid of plasmon absorption in a dielectric/metal/dielectric sandwich terminating a PhC. An SWR peak in spectra of such a plasmonic photonic crystal (PPhC) slab comprising a noble or base metal layer was shown to be sensitive to a negligible variation of refractive index of a medium adjoining to the slab. As a consequence, the considered PPhC-based optical sensors exhibited an enhanced sensitivity and a good robustness in comparison with the conventional surface-plasmon and Bloch surface wave sensors. The PPhC biosensors can be of practical importance because the metal layer is protected by a capping dielectric layer from contact with analytes and, consequently, from deterioration.
Crystals2014, 4(4), 490-497; doi:10.3390/cryst4040490 - published 28 November 2014 Show/Hide Abstract
Abstract: The title compound, fac-triammin-aquo-oxalato-cobalt(III)-nitrate monohydrate, fac-[Co(NH3)3(C2O4)(H2O)]NO3·H2O (2), was prepared according to an original synthetic protocol published exactly 100 years ago by Alfred Werner by dissolving the indigo-blue non-electrolyte complex mer-triammin-chloro-oxalato-cobalt(III), mer-[Co(NH3)3(C2O4)Cl] (1), in boiling half-concentrated nitric acid. Contrary to the literature, it did not crystallize directly from the reaction mixture, but crystallization could be induced by saturating the solution with NaClO4. The structure of 2 has monoclinic (P21/n) symmetry. The crystal structure displays an extensive array of N–H···O and O–H···O hydrogen bonding.
Crystals2014, 4(4), 466-489; doi:10.3390/cryst4040466 - published 26 November 2014 Show/Hide Abstract
Abstract: Various types of coiled carbon filaments have been synthesized using chemical vapor deposition and other methods. These carbon filaments exhibit unique electrical and mechanical properties due to their versatile shapes and structures. To form coiled shapes, different types of catalyst compositions and reactive gases have been explored. Generally, coiled carbon filaments are classified by coil diameter and shape (e.g., microcoil and nanocoil). In this review, coiled carbon filaments are classified into three growth mechanism categories: (1) bidirectional double helical growth; (2) bidirectional twisted growth; and (3) tip single helical or twisted growth. Next, their synthesis methods and hypothetical growth mechanisms are discussed. Then, their electrical and mechanical properties are listed. Finally, potential applications and uses of coiled carbon filament are mentioned.
Crystals2014, 4(4), 450-465; doi:10.3390/cryst4040450 - published 20 November 2014 Show/Hide Abstract
Abstract: Separating functionalized single-wall carbon nanotubes (SWCNTs) from functionalized amorphous carbon is challenging, due to their polydispersity and similar physicochemical properties. We describe a single-step, dialytic separation method that takes advantage of the ability of heavily functionalized SWCNTs to bundle in a polar environment while maintaining their solubility. Experiments on functionalized SWCNTs were compared with functionalized, C60 fullerenes (buckyballs) to probe the general applicability of the method and further characterize the bundling process. This approach may simultaneously be used to purify a functionalization reaction mixture of unreacted small molecules and of residual solvents, such as dimethylformamide.
Crystals2014, 4(4), 439-449; doi:10.3390/cryst4040439 - published 19 November 2014 Show/Hide Abstract
Abstract: The crystal structures of three salts of anionic 5-aminotetrazole are described. The tetramethylammonium salt (P ) forms hydrogen-bonded ribbons of anions which accept weak C–H···N contacts from the cations. The cystamine salt (C2/c) shows wave-shaped ribbons of anions linked by hydrogen bonds to screw-shaped dications. The tetramethylguanidine salt (P21/c) exhibits layers of anions hydrogen-bonded to the cations.