A study of the conformational states of cyclopeptide systems V. NMR spectra of cyclohexapeptides constructed from alanine and glycine residues, the spin-spin coupling constants of the NH-CH protons, and the "pleated-sheet" structure

Summary 1. On the basis of an analysis of the experimental and calculated data on peptide systems containing IMHBs of the 4 1 type, it has been shown that positions 2 and 5 in the preferred conformations of the cyclohexapeptides must be characterized by low values of the³J_NH-CH constants (1–5 Hz), and positions 3 and 6 by large values of these constants (7–10.5 Hz).2. The positions of the IMHBs in cyclohexapeptides including L-alanine and glycine residues have been refined, and the signals of the NH groups in the NMR spectra have been assigned to the individual amino acid residues.3. In the dominating conformations of the cyclohexapeptides, the lateral methyl groups of the alanine residues generally occupy the pseudoaxial orientation in positions 1, 3, 4, and 6 and the pseudoequatorial orientation in positions 2 and 5.For the preceding communication, see [1].M. M. Shemyakin Institute of the Chemistry of Natural Compounds of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 339–346, May–June, 1971.     

Polymer complexes: XLIX—Supramolecular modeling of bonding in novel rare earth polymeric rhodanine drug complexes

Novel supramolecular rare earth polymeric hydrazone complexes of 5-sulphadiazineazo-3-phenyl-2-thiaxo-4-thiazolidinone (HL) of the composition [(Ln)₂(HL)₃(NO₃)₆]_n (where Ln = La(1), Y(2), Pr(3), Nd(4), Sm(5), Gd(6) and Ho(7)) have been prepared and characterized on the basis of their chemical analyses, magnetic measurements, conductance, visible and IR spectral data. Composition, conductance and IR spectral data of complexes show that all these act as a tetradentate ligand. Electronic spectra indicate weak covalent character in the metal–ligand bond. The spectra of Nd³⁺ and Ho³⁺ show characteristic f–f transitions and the metal–ligand covalency in % has been evaluated. The spectral properties of the above polymeric complexes are also discussed.     

Spectral characteristics of the bands of NH groups and structure of 2-thioxobenzazolines in solvents with low polarities

The IR spectra of five 2-thioxo-benzazolines in carbon tetrachloride (2500–3500 cm^–1) and chloroform (3200–3500 cm^–1) are examined. Analysis of the spectral parameters of the absorption band of the unassociated NH groups showed that the high proton-donor capacity of the hydrogen atom of the thioamide group of 2-thioxobenzoxazoline is evidently associated with the high electronegativity of the oxygen atom. The existence of intermolecular hydrogen bonds with a degree of dissociation of 0.3 in carbon tetrachloride and 0.1 in chloroform was established by means of the concentration dependence of the spectra. A change with time in the integral coefficient of the absorption band of the unassociated NH groups was observed in solutions in carbon tetrachloride; this is explained by interaction of the 2-thioxobenzazolines with carbon tetrachloride. The IR spectra, a table of the spectral characteristics, the dependence of the relative integral intensity on the concentration, and the dependence of the optical density of the absorption band of free NH groups on time are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 69–71, January, 1979.     

Infrared absorption spectra of some derivatives of 1,2,3,4-tetrahydro-Β-carboline

The IR absorption spectra in 3800-1400 cm^–1 region of 1-propyl-, 1-carboxy-, 1-carboxy-1-methyl-, and 1-benzyl-1-carboxy-6-hydroxy-1,-tetrahydro--carbolines, their O-methyl derivatives, and their hydrochlorides are discussed. An assignment of the bands due to the stretching vibrations of NH, NH ₂ ⁺ , OH, COO^–, and COOH groups is proposed. The hypothesis has been put forward that strong intermolecular and intramolecular hydrogen bonds exist in the substances studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 775–778, June, 1970.     

Comparative IR spectroscopic study of phosphorus-containing dendrimers built of thiophosphoryl, cyclophosphazene and phthalocyanine cores

The FTIR spectra of four generations of phosphorus-containing dendrimers built of thiophosphoryl, cyclophosphazene and phthalocyanine cores with terminal benzaldehyde and P–Cl groups have been recorded and analyzed. FT-Raman spectra of four generations of phosphorus dendrimers built of cyclotriphosphazene core with terminal benzaldehyde groups have been detected. Their spectral pattern is determined by the ratio T_n/R_n (T_n—number of terminal groups, R_n—number of repeating units). This ratio trends to r − 1 (r—branching functionality of repeating unit), and becomes constant, when the generation number is higher than 3. Experimental IR spectra of dendrimers built of thiophosphoryl, cyclophosphazene and phthalocyanine cores are very closely similar. The dependence of band full width at half height in IR spectra on the number of dendrons is established. The possibility appears to separate the bands assigned to the core, repeating units and terminal groups of dendrimers by difference spectroscopy method.     

Tungsten/Alumina Catalysts: Effect of H3PW12O40 Countercation on Surface Properties and Hydrodesulfurization Activity

H₃PW₁₂O₄₀ heteropoly acid (HPW₁₂) and its Co, Fe, Ni salts supported on alumina have been used to model hydrodesulfurization catalysts of different activity. All catalysts revealed a promoting effect of the countercation in thiophene hydrodesulfurization, that of the nickel cation being the highest. The catalysts were characterized by measurements of surface area, HDS activity, TPR, FTIR, and DR spectra. IR spectra confirmed an effect of the countercation on the phase composition of the supported heteropoly compounds. 12-Tungstoaluminate heteropoly anions and coordinately unsaturated anions of HPW₁₂ were detected in the IR spectra of the catalysts. The hydrotreating activity of the catalysts was proportional to the amount of hydrogen consumed in the range 20–500°C during TPR.     

Synthesis and IR spectra of 2-phenylbenzimidazole and its amino derivatives

2-Phenylbenzimidazole and its mono and diamino derivatives were synthesized in yields up to 85% by cyclodehydration of o-aminobenzanilides in hydrochloric or sulfuric acid. The IR spectra of the compounds obtained were studied, the principal bands of the stretching and deformation vibrations of the NH and NH₂ groups were assigned, and the presence of associates with a hydrogen bond was established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–116, January, 1973.     

Synthesis and Structure of 4-Trifluoromethylsulfonamidotrichloroethyl-5-chloropyrazoles

Reactions of trifluoromethanesulfonic acid N-(2,2,2-trichloroethylidene)amide with 1,3-dialkyl-5-chloropyrazoles and 1-phenyl-3-methylpyrazole afforded 4-(amidotrichloroethyl)-substituted pyrazole derivatives. 4-Chloropyrazoles were not involved into this process. The structure of compounds synthesized was studied by means of IR and NMR spectroscopy. The presence of intra- and intermolecular hydrogen bonds was revealed by a decrease in the absorption frequencies and a complicated form of ν(NH) and ν_as(SO₂) absorption bands in the IR spectra, and also in splitting of signals in ¹H and ¹³C NMR spectra.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 749–752.Original Russian Text Copyright © 2005 by Kondrashov, Rozentsveig, Sarapulova, Larina, Levkovskaya, Savosik, Bozhenkov, Mirskova.     

Radiation effects on thermal decomposition of ammonium perchlorate

Thermal decomposition of -irradiated (dose: 0–3.6 MGy) ammonium perchlorate was followed. The dynamic heating (range: 100–220 °C) and IR spectral measurements were carried out simultaneously. Temperature and dose brought a lowering in peak intensity of NH ₄ ⁺ and C10 ₄ ^– ions. Radiolytic products C10₃ and NH₃ are considered to initiate the decomposition process.     

(NH4)4M(Zr(Hf))3F17 · 2HF Complexes (M = Li,Na): Synthesis and Physicochemical Properties

Monoclinic crystals of ammonium hydrofluoride fluoro complexes of zirconium and hafnium (NH₄)₄M(Zr(Hf))₃F₁₇ · 2HF (M = Li, Na) are synthesized and studied. Their unit cell parameters are determined. IR spectra of the synthesized compounds are measured in the range of 350–4000 cm^–1.     

An investigation and identification of polysaccharides isolated from archeological specimens

Summary Polymeric compounds have been isolated from archeological specimens (fragments of Central Asian paintings of the 2nd-19th centuries). A comparison of their IR spectra with the spectra of plant gums has shown that they are polysaccharides which have remained undestroyed for up to 1800 yr. In some cases it has been possible from the IR spectra and composition of the extracted polysaccharides to provisionally identify sourcherry or apricot gum, of which these polysaccharides were components.All-Union Central Scientific-Research Laboratory for Conservation and Restoration, Moscow. M. M. Shemyakin Institute of Bioorganic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 15–19, January–February, 1976.     

Synthesis and characterization of adducts of dichlorosulphato bis(1,3-propylenediamine)metal(II) complexes with dialkyltin dichlorides

Summary Adducts of dichlorosulphato bis(1,3-propylenediamine)-metal(II) complexes with dialkyltin dichlorides, [R₂Sn(MeCN) ₂]₂[M(NH(CH₂)₃NH)₂(SO₃Cl)₂] (M = Cr, Fe, Co, Ni or Cu; R = Me or n-Bu) have been prepared. The positive shift in the symmetric SO₃ stretch and splitting of the doubly degenerate (E) modes in their i.r. spectra suggest a covalent linkage for the SO₃Cl^– group. The adducts are non-electrolytes; magnetic moments and ligand field data suggest that each SO₃Cl^– group is monodentate, generating an octahedral geometry around the metal ions, except for Ni^II where tetragonal distortion is observed.Author to whom all correspondence should be directed.     

Ions with a strong symmetric H-bond in solutions of sodium acetate in acetic acid

The multiple attenuated total reflection IR spectra of solutions of sodium acetate in acetic acid have been recorded in the range from 9000 to 4000 cm^–1. The CH₃COO^– anion and an acid molecule form be complex (CH₃COO...H...OOCCH₃) with a strong symmetric H-bond.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp, 1854–1857, July, 1996.     

Spektroskopische Untersuchungen an R3MF-Verbindungen (M = Si,Ge, Sn)

Spectroscopical Investigations on R₃MF Compounds (M = Si, Ge, Sn) The IR and RAMAN spectra of a number of R₃MF compounds (M? Si, Ge, Sn) have been recorded. The frequencies of the vibrational spectra were almost completely assigned. The measurements of the IR-spectra were investigated (as for as possible) in all states of aggregations. The force of the intermolecular interactions were discussed by means of the spectroscopic data.     

Synthesis and IR spectra of some derivatives of phenanthridine and 4,9-diazapyrene

A number of acylamino- and diacylaminobiphenyls and the corresponding derivatives of phenanthridine and 4, 9-diazapyrene, including the previously unknown 2,2-dipropionamidobiphenyl, 5, 10-diethyl-4, 9-diazapyrene, 2, 4-dibenzamidobiphenyl, and 3-benzamido-6-phenylphenanthridine, have been synthesized. The IR spectra of all the compounds have been studied and a group of bands characteristic for the phenanthridine ring in the 1570–1620 cm^–1 region and a group of five bands characteristic for the 4, 9-diazapyrene ring in the 1330–1640 cm^–1 region have been identified. The nature of the IR spectra of phenanthridine derivatives containing unsubstituted amide groups has also been established.     

Fragmentation of some 1,2-epoxyguaianolides

The mass spectra of four guaianolides with epoxy groups of C₁–C₂ have been studied. A mechanism is proposed for the formation of the main ions. The origin of the secondary fragments has been confirmed by measurements of elementary compositions.Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 796–800, November–December, 1980.     

Dinitramide and its salts

The vibrational and electronic spectra of dinitramide salts MN(NO₂)₂ (M=K, Na, Li, NH₄, Fe, Ag, Mn, Mg, Rb, C(NH₂)₃) have been studied. The IR and Raman spectra of solutions and melts of the salts have been satisfactorily interpreted on the basis of the anion model withC _2v symmetry. The complication of the spectra in the crystalline phase has been explained by restructurization of the anion that reduces its symmetry and makes the nitro groups nonequivalent.For part 6, seeIzv. Akad. Nauk, Ser. Khim., 1995, 113 [Russ. Chem. Bull.,44, 108 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1508–1512, August, 1995.     

Synthesis and characterization of complexes of lanthanide nitrates with N,N′-dinaphthyl-N,N′-diphenyl-3,6-dioxaoctanediamide

Solid complexes of lighter lanthanide nitrates with N,N′-dinaphthyl-N,N′-diphenyl-3,6-dioxaoctanediamide (DDD), Ln(NO₃)₃(DDD) (Ln = La---Nd, Sm) have been prepared in non-aqueous media. These complexes have been characterized by elemental analysis, conductivity measurements, IR spectra, electronic spectra and TG-DTA techniques. In all the complexes, DDD and NO₃⁻ are coordinated to the lanthanide ions as tetradentate and bidentate ligands, respectively. The differences in the IR and electronic spectra between these complexes and lanthanide nitrate complexes with N,N,N′,N′-tetraphenyl-3,6-dioxaoctanediamide (TDD) are discussed.     

Synthesis and physicochemical study of hexafluorocomplexes of tin with mixed alkali metal cations

Conclusions Hexafluorocomplexes of tin with mixed cations of alkali metals with the composition NaMSnF₆ (M=K, Rb, Cs) and crystallizing in the orthorhombic system have been synthesized for the first time from aqueous solutions. The parameters of the unit cells of these substances have been determined.The compounds synthesized are optically positive biaxial crystals; their optical and x-ray diffraction constants are given.In the IR spectra of all the fluorocomplexes synthesized a splitting is observed in the frequency of the stretching vibration (₃) for the octahedral anion SnF₆ ^2–.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1927–1931, September, 1987.     

Optimization of the geometry and electronic structure of bridged binuclear aromatic molecules

The geometries of the molecules of (C₆H₅)₂M, where M=NH, PH, O, S, CO, CS, SO, CH=CH, CH=N, N=N, and N=NO, the diphenylamine radical cation, and the diphenylnitrogen and diphenyl nitroxide radicals have been optimized by the CNDO/2, INDO, and MINDO/3 methods, and their electronic structures have been calculated. The data obtained have been interpreted in light of the investigation of the problem of reactivity.N. G. Chernyshevskii Saratov State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 23–29, March–April, 1991.