Stars and stripes: hexatopic tris(3,2':6',3"-terpyridine) ligands that unexpectedly form one-dimensional coordination polymers

The hexatopic ligands 1,3,5-tris(4,2':6',4''-terpyridin-4'-yl)benzene (1), 1,3,5-tris(3,2':6',3''-terpyridin-4'-yl)benzene (2), 1,3,5-tris[4-(4-(4,2':6',4''-terpyridyl)phenyl]benzene (3), 1,3,5-tris[4-(4'-3,2':6',3''-terpyridyl)phenyl]benzene (4) and 1,3,5-tris[4-(4'-3,2':6',3''-terpyridyl)phenyl]mesitylene (5) have been prepared and characterized. The single crystal structure of 1.1.75DMF was determined; 1 exhibits a...

Facile Synthesis of Stacked Ni(OH)2 Hexagonal Nanoplates in a Large Scale

Using NiCl2 and NaOH as raw materials, stacked Ni(OH)2 hexagonal nanoplates with different edge lengths were prepared in a large scale by a simple hydrothermal route. The stacked Ni(OH)2 structure was composed of a certain amount of parallel Ni(OH)2 hexagonal nanoplates along the (001) direction. Each parallel Ni(OH)2 nanoplate had a single-crystal structure, and the exposed planes were (001), (00−1), and (100). The formation mechanism of the stacked Ni(OH)2 structures was discussed on the basis of the Ni(OH)2 crystal structure.

Na doping into Li-rich layered single crystal nanoparticles for high-performance lithium-ion batteries cathodes

Lithium-rich layered manganese-based cathodes (LRLMOs) with first-class energy density (∼1000 W h kg−1) have attracted wide attention. Nevertheless, the weak cycle stability and bad rate capability obstruct their large-scale commercial application. Here, single crystal Li1.2−xNaxNi0.2Mn0.6O2 (x = 0, 0.05, 0.1, 0.15) nanoparticles are designed and successfully synthesized due to the single crystal structure with smaller internal stress and larger ionic radius of Na. The synergistic advantages of single crystal structure and Na doping are authenticated as cathodes for Li ion batteries (LIBs), which can consolidate the crystallographic structure and be benefit for migration of lithium ion. Among all the Na doping single crystals, Li1.1Na0.1Ni0.2Mn0.6O2 cathode possesses supreme cycling life and discharge capacity at large current density. To be more specific, it exhibits a discharge capacity of 264.2 mAh g–1 after 50 charge and discharge cycles, higher than that of undoped material (214.9 mAh g–1). The discharge capacity of Li1.1Na0.1Ni0.2Mn0.6O2 cathode at 10 C (1 C = 200 mA g−1) is enhanced to 160.4 mAh g−1 (106.7 mAh g–1 for x = 0 sample). The creative strategy of Na doping single crystal LRLMOs might furnish an idea to create cathode materials with high energy and power density for next generation LIBs.

X-ray Single Crystal Structure, Tautomerism Aspect, DFT, NBO, and Hirshfeld Surface Analysis of a New Schiff Bases Based on 4-Amino-5-Indol-2-yl-1,2,4-Triazole-3-Thione Hybrid

Four different new Schiff basses tethered indolyl-triazole-3-thione hybrid were designed and synthesized. X-ray single crystal structure, tautomerism, DFT, NBO and Hirshfeld analysis were explored. X-ray crystallographic investigations with the aid of Hirshfeld calculations were used to analyze the molecular packing of the studied systems. The H···H, H···C, S···H, Br···C, O···H, C···C and N···H interactions are the most important in the molecular packing of 3. In case of 4, the S···H, N···H, S···C and C···C contacts are the most significant. The results obtained from the DFT calculations indicated that the thione tautomer is energetically lower than the thiol one by 13.9545 and 13.7464 kcal/mol for 3 and 4, respectively. Hence, the thione tautomer is the most stable one which agree with the reported X-ray structure. In addition, DFT calculations were used to compute the electronic properties while natural bond orbital calculations were used to predict the stabilization energies due to conjugation effects. Both compounds are polar where 4 (3.348 Debye) has a higher dipole moment than 3 (2.430 Debye).

Recommended X-ray single-crystal structure refinement and Rietveld refinement procedure for tremolite

A detailed description of the structure of the amphibole-supergroup minerals is very challenging owing to their complex chemical composition that renders the process of cation partition extremely difficult, particularly because of the occurrence of multivalent elements. Since amphiboles naturally occur under a fibrous morphology and have largely been used to produce asbestos, there is a growing demand for detailed and accurate structural data in order to study the relationships between structure, composition and toxicity. The present study proposes a recommended refinement procedure for both X-ray single-crystal structure refinement (SREF) and Rietveld analysis for tremolite, selected as a test case. The corresponding structural results are compared to estimate the `degree of confidence' of the Rietveld refinement with regard to SREF. In particular, it is shown that the interpretation of the electron density of the tremolite structure by SREF is model dependent. By assuming that the site-scattering values from SREF should be as close as possible to those from electron microprobe analysis, as a crucial constraint for the correct description of the final crystal-chemical model, it is found that it is best satisfied by using partially ionized scattering curves (SCs) for O and Si, and neutral SCs (neutral oxygen curves or NOCs) for other atoms. This combination leads to the best fit to the diffraction data. Moreover, it is found that Rietveld refinement using NOCs produces the best structural results, in excellent agreement with SREF. It is worth noting that, due to the complexity of the diffraction pattern and the fairly large number of freely refinable parameters, refinements with different combinations of SCs produce results almost indistinguishable from a statistical point of view, albeit showing significant differences from a structural point of view.