tert-Butylthiacalix[4]arene monolayers as a biomimetic model for the oxidation of antioxidants with cytochrome c

The possibility of designing a model of sensor to antioxidants based on thiacalix[4]arene monolayers with immobilized cytochrome c was shown. The molecular surface area S ₀ of thiacalix[4]arene in the monolayers and the surface pressure coefficient ?dπ/dS (elasticity) reflect changes in the redox state of cytochrome c in the presence of dihydroquercetin and ascorbic acid in the aqueous subphase. The absorption spectra in the visible and UV ranges of solutions of the subphase and transferred thiacalix[4]arene monolayers with immobilized cytochrome c confirm the oxidation of the antioxidants to quinones and formation of the reduced form of cytochrome c.     

Density functionals for exchange and correlation energies: Exact conditions and comparison of approximations

A set of exact conditions is compiled for the purpose of developing and testing approximations for the exchange-correlation energy as a functional of the electron density. Special emphasis is placed upon recently developed density-scaling relationships. Commonly used generalized gradient approximations are compared against several of these conditions. A direct tabular comparison of these functionals (not of calculated properties) with one another is also made. © 1994 John Wiley & Sons, Inc.     

Synthesis and spectral data of quinoline products obtained by reaction of N‐(4‐pyridinyliden)anilines and N‐benzylidenaniline with 2,2‐dimethoxypropane (kametani reaction)

A study on interaction between N‐(4‐pyridinyliden)anilines 1‐4 and 2,2‐dimethoxypropane under Kametani reaction conditions was realized. According to the GC‐MS analysis of crude reaction, besides the needed 4‐methyl‐2‐(4‐pyridinyl)quinolines 5‐8 , three collateral products: secondary amines 9‐12 , 4‐(2‐methylprop‐1‐enyl)quinolines 13‐16 and 4‐(2‐methoxy‐2‐methylpropyl)quinolines 17‐20 were formed. Unexpected quinolines 13‐16 as well the desired quinolines 5‐8 were isolated and fully characterized. In contrast, a condensation of N‐benzylidenaniline 21 with 2,2‐dimethoxypropane afforded a set of different quinoline products.     

Intercalation of 1,2-Alkanediols into α-Zirconium Hydrogenphosphate

Intercalation compounds of α-Zr(HPO₄)₂ · H₂O with 1,2-alkanediols (from C3 to C16) have been prepared by replacing 1-propanol in α-Zr(HPO₄)₂ · 2C₃H₇OH with the desired 1,2-alkanediols by a treatment in a microwave field. It was found that the intercalates contain 1.5 molecules of diol per formula unit. The diol molecules are placed between the host layers in a bimolecular way with their aliphatic chains tilted at an angle of 51°. The diol molecules are anchored in the interlayer space by H-bonds. A mixed intercalate, containing 1,2-butanediol and 1,2-decanediol in a roughly equimolar ratio, is formed when the α-Zr(HPO₄)₂ · 2C₃H₇OH intercalate, suspended in a mixture of 1,2-butanediol and 1,2-decanediol, is exposed to microwave radiation. No new phase containing both types of the guest molecules was observed when the 1-propanol intercalate, suspended in a mixture of 1-propanol and 1,2-octanediol, is exposed to microwave radiation.     

Specifics of reactions of cerium sulfate and europium sulfate with hydrogen

Reactions of cerium sulfate and europium sulfate with hydrogen have been studied. Diagrams showing the evolution of phase composition of the polycrystalline products of reaction between europium sulfate and hydrogen are constructed. The reaction of Ce₂(SO₄)₃ with hydrogen at 600°С consecutively yields Ce₂O₂S and Ce₂O₃ phases. At 800°С the batch is >95 mol % Ce2O3. At 480-500°С, a single-phase sample of EuSO4 is prepared; at 600-1000°С, Eu₂O₂S is prepared; and at 1050°С, the batch is >95 mol % Eu₂O₂S and up to 5 mol % Eu₂O₃. Atomic-force microscopy shows that europium sulfate grains, which represent agglomerates of particles 10-20 μm in size, are degraded upon reaction with hydrogen into individual ovalshaped particles sized 40-60 × 130-200 nm.     

Synthesis and conformational analysis of 6-[N,N-bis(dihydroxyphosphorylmethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphorinane-4-methylphosphonic acid by NMR spectroscopy

The Kabachnik—Fields methylphosphorylation of 1,3-diaminopropan-2-ol affords a mixture of 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetrakismethylphosphonic acid and its intramolecular cyclic ester. Subsequent heating of this mixture led to the thermal dehydration of the acid with the 1,4,2-oxazaphosphorinane ring closure and the formation of 6-[N,N-bis(dihydroxyphosphorylmethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphorinane4-methylphosphonic acid. A predominant chair conformation of the formed six-membered heterocycle was inferred from the data of 2D homonuclear (¹H, ¹H; J-resolved) and heteronuclear (¹H, ¹³C; HSQC, HMBC) NMR correlation spectra.     

Hydration numbers of sea water basic ions found by the pulse method of proton NMR

Hydration numbers of basic ions in sea water (SW) are found from a proton relaxation rate of 1/T ₁ in SW and model solutions. A possibility for the formation of three-layer hydrate shells around main SW cations and two-layer shells around anions is ascertained. About half of water molecules is in influence zones of ions in sea water that correlates with a double shift in the baric dependence maximum of T ₁ to a smaller pressure in SW relative to pure water.     

Immobilization of proteolytic enzymes trypsin and α-chymotrypsin to cellulose matrix

Trypsin and α-chymotrypsin were immobilized on a microcrystalline cellulose matrix by adsorption interaction with cellulose. The adsorption of enzymes was determined as a function of their concentration and the pH of solutions. Mechanisms of enzyme binding to functional groups of cellulose were suggested.