Bicyclo[1.1.0]butadiene (trialene): An experimentally viable molecule?

Molecular orbital calculations on the C₄H₂ potential energy surface indicate singlet trialene (1) not only to be thermodynamically unstable, but also to have negligible barriers to interconversion to diacetylene.     

Ring size effects on 1,2-shifts in carbocations

1,2-Hydride shift barriers in classical carbenium ions increase with decreasing ring size; this can be attributed to the increased strain of the H bridged structures in the small rings.     

Pressure-induced valence instability in Sm4Bi3

Sm₄Bi₃ has the anti-Th₃P₄ (cubic) structure with three Sm²⁺ ions and one Sm³⁺ ion. The compound undergoes a first-order, isostructural transition at about 26 kbar. The resistance abruptly decreases by a factor of three and the volume by about 10%. The Sm²⁺ ions undergo a change towards the 3⁺ state in the transition and the material goes from semimetallic to a metallic state. The behavior of the resistance anomaly suggests termination of the phase boundary at a critical point.     

Valence instability in an Anderson lattice system: CeAl2

We report the existence of a volume collapsed strongly mixed valent state at pressures above 65 K bars in the prototype “concentrated Kondo” system CeAl₂ and discuss the relevant energy scales and general phase diagram of CeAl₂. To our knowledge this is the first demonstrated example of what should be a large class of systems exhibiting the full diversity of ground states of an Anderson lattice.     

Solvothermal synthesis of hierarchically porous CeO2 nanopalm leaves and their photocatalytic properties

Hierarchically porous CeCO₃OH palm leaves were synthesized by using a facile solvothermal method at 180 °C utilizing cerium nitrate and ethylene glycol. Polycrystalline CeO₂ palm leaves were obtained from the thermal decomposition-oxidation process of the CeCO₃OH nanostructures. CeCO₃OH and CeO₂ palm leaves were characterized by X-ray diffraction pattern, scanning electron microscopy image, energy dispersive X-ray analyses, and ultraviolet (UV)–visible spectroscopy images. The CeO₂ palm leaves exhibited a significant photocatalytic performance in degrading azo dye acid orange II in an aqueous solution under an UV radiation. The formation mechanisms of the CeCO₃OH/CeO₂ nanostructures were described on the basis of the experimental results.     

From Containers to Catalysts: Supramolecular Catalysis within Cucurbiturils

Cucurbiturils are a family of molecular container compounds with superior molecular recognition properties. The use of cucurbiturils for supramolecular catalysis is highlighted in this concept. Both photochemical reactions as well as thermal transformations are reviewed with an eye towards tailoring substrates for supramolecular catalysis mediated by cucurbiturils.     

Application of principal component analysis to gas sensing characteristics of Cr0.8Fe0.2NbO4 thick film array

The transient changes in resistances of Cr_0.8Fe_0.2NbO₄ thick film sensors towards specified concentrations of H₂, NH₃, acetonitrile, acetone, alcohol, cyclohexane and petroleum gas at different operating temperatures were recorded. The analyte-specific characteristics such as slopes of the response and retrace curves, area under the curve and sensitivity deduced from the transient curve of the respective analyte gas have been used to construct a data matrix. Principal component analysis (PCA) was applied to this data and the score plot was obtained. Distinguishing one reducing gas from the other is demonstrated based on this approach, which otherwise is not possible by measuring relative changes in conductivity. This methodology is extended for three Cr_0.8Fe_0.2NbO₄ thick film sensor array operated at different temperatures.     

Photoreactions with a Twist: Atropisomerism‐Driven Divergent Reactivity of Enones with UV and Visible Light

Light‐induced transformation of atropisomeric and achiral enones displays divergent reactivity. Photocyclization leading to 3,4‐dihydroquinolin‐2‐one was observed with achiral enone carboxamide, whereas the atropisomeric enone carboxamides underwent hydrogen abstraction leading to spiro‐β‐lactams. Detailed photochemical, photophysical, and theoretical investigations have provided insight into this divergent reactivity and selectivity.     

Effect of tilt and astigmatism aberration of turbulent atmosphere on the intensity distributions of a LG11 beam

The effects of turbulent aberration such as z-tilt aberration, and astigmatism on the intensity distribution of double ring shaped LG₁₁ beam have been investigated using the Fresnel–Kirchhoff diffraction integral and the quadratic approximation. The effect of turbulent aberration on the intensity distributions at the focal plane with different turbulent strength, and propagation distance is analyzed numerically. It is observed that the effect of tilt aberration gives major effect on the intensity distribution of the LG_(1,1) beam in the turbulent atmosphere.