Unprecedented migration of a methyl group in 2-(2',6'-dimethylphenylazo)-4-methylphenol mediated by ruthenium

An unprecedented chemical transformation of 2-(2',6'-dimethylphenylazo)-4-methylphenol has been observed upon its reaction with [Ru(PPh(3))(2)(CO)(2)Cl(2)] whereby the methyl group at the 2' position migrates to the 4' or 6' position.     

A facile route to the synthesis of pyrimido[2,1-b]quinazoline core from the primary allyl amines afforded from Baylis–Hillman adducts

A highly simplified approach for the generation of substituted pyrimido[2,1-b]quinazoline core from the primary allyl amines afforded from the Baylis–Hillman adducts is described. Sequential reductive alkylation of the primary allyl amine with 2-nitrobenzaldehyde, reduction of the aromatic nitro group with In, CNBr-promoted intramolecular cyclization followed by NaOMe-mediated another intramolecular cyclization furnish the title compounds.     

Temperature-Dependent Photoluminescence of Hexafluorobenzene-Intercalated Phenethylammonium Tin Iodide 2D Perovskite

Tin halide perovskites are potential alternatives of lead halide perovskites. However, the easy oxidation of Sn²⁺ to Sn⁴⁺ brings in a challenge. Recently, layered two-dimensional hybrid tin halide perovskites have been shown to partially resist the oxidation process because of the presence of hydrophobic organic molecules. Consequently, such layered hybrid perovskites are being explored for optoelectronic applications. The optical properties of layered tin halide perovskites depend on the interlayer separation and the dielectric mismatch between the organic and inorganic layers. Intercalation (insertion) of a molecular species between the layers modifies the interlayer interactions affecting the optical properties of layered hybrid perovskites. We investigated the effect of hexafluorobenzene (HFB) intercalation in phenethylammonium tin iodide [(PEA)₂SnI₄] using temperature-dependent (6 K to 300 K) photoluminescence (PL). HFB intercalation increases the bandgap. A strong PL quenching is observed in pristine (PEA)₂SnI₄ below 150 K, probably because of the presence of non-emissive states. HFB intercalation suppresses the influence of such non-emissive states resulting in an increase in PL intensity at the cryogenic temperatures. Our results highlight that a simple molecular intercalation (non-covalent interaction) into layered hybrid perovskites can significantly tailor the electronic and optical properties.     

Electron transport and magnetic properties of some mixed-valent alkalithiocuprates

Electrical transport properties of some two-dimensional isostructural compounds KCu₄S₃, RbCu₄S₃, and CsCu₄S₃ and a one dimensional conductor Na₃Cu₄S₄ have been investigated. Conductivities have been measured on pelletized materials in the temperature range 300 to 150 K. All of them behave as metallic conductors. The room temperature conductivities of these compounds are KCu₄S₃, 1600 Ω^?1 cm^?1; RbCu₄S₃, 1400 Ω^?1 cm^?1; CsCu₄S₃, 1250 Ω^?1 cm^?1; Na₃Cu₄S₄, 700 Ω^?1 cm^?1. The observed trend in conductivities among the isostructural compounds may be rationalized either on the basis of shortest CuCu distances or on the carrier charge concentrations per unit volume. All of these compounds behave as Pauli paramagnetic materials.     

Noise current spectrum in submicrometer samples

The noise current spectral density in submicrometer samples is computed using the Monte Carlo method. The normalized spectral density is found to decrease with sample length and increase with the field. The high-field noise is like shot noise and increases with current in agreement with experimental results.     

Broad Dual Emission by Codoping Cr3+ (d→d) and Bi3+ (s→p) in Cs2Ag0.6Na0.4InCl6 Double Perovskite

A phosphor emitting both white light and broad near-infrared (NIR) radiation can simultaneously provide visual inspection and early signs of rotting of food products. The broad NIR emission is absorbed by the vibrational overtones of water molecules present in food items, providing the non-invasive image contrast to assess the food freshness. Here we design a phosphor, namely, Cr³⁺-Bi³⁺-codoped Cs₂Ag_0.6Na_0.4InCl₆, that simultaneously emit warm white light and broad NIR (1000 nm) radiation with quantum yield 27 %. This dual emitter is designed by combining the features of s²-electron (Bi³⁺) and d³-electron (Cr³⁺) doping in a weak crystal field of the halide perovskite host. excitation of Bi³⁺, using a commercial 370 nm ultraviolet light-emitting-diodes (UV-LED), yields both the emissions. A fraction of the excited Bi³⁺ dopants emit the warm white light, and the other fraction transfers its energy non-radiatively to Cr³⁺. Then the Cr³⁺ de-excites emitting broad NIR emission. Temperature dependent (6.4–300 K) photoluminescence in combination with Tanabe-Sugano diagram show that the Cr³⁺ experiences a weak crystal field ( =2.2), yielding the NIR emission. As a proof of concept, we fabricated a panel containing 122 phosphor-converted LEDs, demonstrating its capability to inspect food products.