Efficient Synthesis of 3-(4-Carboxyphenyl)pyridine-2,6-dicarboxylic Acid

Russian Journal of Organic Chemistry - An efficient synthetic approach to 3-(4-carboxyphenyl)pyridine-2,6-dicarboxylic acid has been developed on the basis of “1,2,4-triazine”...     

Magnetic diagram of CuCr<Subscript>2 – <Emphasis Type="Italic">x</Emphasis></Subscript>Sb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Sе<Subscript>4</Subscript> solid solutions

Temperature-dependent magnetization was measured for CuCr_2–x Sb _x Sе₄ solid solutions in the range 300–5 K in a weak field (50 Oe) and a strong field (10 kOe) and in an ac magnetic field having a frequency of 100–10000 Hz and an amplitude of Н = 1 Oe. The type and character of magnetic transitions under investigation in the system were determined, and its magnetic phase diagram was constructed.     

Magnetic Phase Diagram of Solid Solutions in the CoCr<Subscript>2</Subscript>S<Subscript>4</Subscript>–Cu<Subscript>0.5</Subscript>Ga<Subscript>0.5</Subscript>Cr<Subscript>2</Subscript>S<Subscript>4</Subscript> System

The magnetic phase diagram of solid solutions in the CoCr₂S₄–Cu_0.5Ga_0.5Cr₂S₄ system was constructed. The widest concentration range (0.38 < x < 1) in the diagram represents solid solutions based on the ferrimagnetic semiconductor CoCr₂S₄ (T_C = 223 K), which exhibits unusual properties in the magnetic ordering region while measuring the temperature dependence of the dynamic susceptibility. The magnetic properties were studied with a Quantum Design PPMS-9 platform within the temperature range 5–300 K in a 100-Oe constant magnetic field and/or a varying (100-, 500-, and 1000-Hz) magnetic field with an amplitude of 1 Oe.     

Quantum oscillations of resistance and magnetization in the degenerate semiconductor n-HgCr2Se4

In the magnetic field range ΔH=8–60 kOe we observed and studied the anomalous oscillations in the magnetic field dependence of the resistance and magnetization of single crystals of n-HgCr₂Se₄. The absence of periodicity in 1/H in the ΔH=8–20 kOe range can be explained by the non-Fermi-liquid behavior of the electron subsystem and agrees with the theory of the de Haas-van Alphen in systems with intermediate valence. In stronger fields, ΔH=20–60 kOe, the amplitude of the fundamental harmonic decreases, with the number and amplitude of the higher-order harmonics increasing. As a result, noise is superimposed on the signal as magnetic field strength grows. The temperature dependence of the magnetization is the sum of the monotonic spin-wave contribution and the oscillating part. Zh. éksp. Teor. Fiz. 113, 1877–1882 (May 1998)     

One-Pot Preparation Method of 5-Alkyl-3-(benzo)pyridyl-1,2,4-triazines

Russian Journal of Organic Chemistry - Convenient one-pot method was developed for the preparation of 5-alkyl-3-(2-pyridyl)-, 5-alkyl-3-(4-pyridyl)- or 5-alkyl-3-(quinolin-2-yl)-1,2,4-triazines in...     

An efficient route to 5-(hetero)aryl-2,4′- and 2,2′-bipyridines through readily available 3-pyridyl-1,2,4-triazines

A new route to substituted bipyridines based on a new method for the synthesis of substituted 3-pyridyl-1,2,4-triazines and their aza-Diels-Alder reactions is shown to be an efficient strategy for the preparation of structurally diverse bipyridine ligands.     

5-Aryl-2,2′-bipyridines as tunable fluorophores

Readily available 5-aryl-2,2′-bipyridines and their derivatives are a unique family of fine-tunable chromophores, where changes in the substitution patterns, solvation and coordination are translated into dramatic spectral changes. They exhibit sensitive and selective response to zinc ions with dramatic increases in emission intensity or significant red-shifts of emission maxima.     

Magnetic properties of CuCr<Subscript>2–<Emphasis Type="Italic">х</Emphasis></Subscript>Sb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>4</Subscript> (<Emphasis Type="Italic">х</Emphasis> = 0–0.5) solid solutions

Magnetic properties of spinel solid solutions CuCr_2–х Sb _x Se₄ (х = 0–0.5) were measured in the temperature range 5–300 K in a constant (50 Oe and 10 kOe) magnetic field. The results are interpreted in terms of the ionic model suggested earlier for CuCr₂Х₄ compounds.     

Interaction between Cr2Se3 and Cu2GeSe3

The interaction along the Cu₂GeSe₃-Cr₂Se₃ join has been investigated using differential thermal and X-ray powder diffraction analyses. It has been found that the join is quasi-binary with a degenerate eutectic based on the Cu₂GeSe₃ compound. Two new quaternary compounds have been found along the join, namely, Cu₂GeCr₆Se₁₂ and the γ phase. The phase is formed at 915°C by the peritectic reaction L + β-Cr₂Se₃ = γ and has the primary crystallization region up to 9 mol % Cr₂Se₃ in the temperature range 758–915°C. The room-temperature homogeneity range of the γ phase is 65–70 mol % Cr₂Se₃. The Cu₂GeCr₆Se₁₂ compound is formed by the peritectoid reaction γ + β-Cr₂Se₃=Cu₂GeCr₆Se₁₂ at 880°C, and its homogeneity range is 73–79 mol %. The X-ray reflections of the γ phase are indexed for the tetragonal crystal system with the unit cell parameters a = 12.043 Å and c = 9.180 Å. Samples with ferromagnetic properties are found in the homogeneity regions of both compounds.