DFT and Raman study of all-trans astaxanthin optical isomers

Astaxanthin (AST) is a xanthophyll carotenoid widely distributed in aquatic animals, which has many physiological functions such as antioxidant, anti-inflammatory, anti-hypertensive and anti-diabetic activities. Astaxanthin has three optical isomers, including a pair of enantiomers (3S,3 ‘S and 3R,3 ‘R) and a meso form (3R,3 ‘S). Different optical isomers have differences in a variety of physiological functions. Traditionally, High Performance Liquid Chromatography (HPLC) can be used to distinguish these isomers. In this work, it’s found that Raman spectroscopy can be employed to distinguish the three optical isomers. Because the intensities of two Raman bands at 1190 cm-1 and 1215 cm-1 of three isomers are different. DFT calculations are performed and used to analyze the spectral differences. The calculation results show that the structures of these chiral isomers are not strictly mirror-symmetrical to each other, which leads to the difference in their Raman spectra.HighlightsRaman spectroscopy can be utilized to distinguish three optical isomers of all-trans astaxanthin.The DFT-calculated spectrum is used to explain why the Raman bands of optical isomers at 1190 and 1215 cm-1 are different.The structural parameters of the three optical isomers have been identified.

CEPHUS PYGMAEUS INFLUENCE FOR SOFT WINTER WHEAT ELEMENTS YIELD IN THE FOREST SAMARA REGION

The purpose of the study is to reduce yield loss of winter wheat crops infested with stem borer. The studies were conducted in the forest of the Samara region in the vicinity of st. Ust-Kinelsky in 2011, 2012 and 2014. in the fields of the Povolzsje Science Research Institute of selection and seeds production of P. N. Konstantinov with the meso form of the relief at the landscape profile length of about 8 m to 4 varieties of soft winter wheat: Povolgskaya 86, Kinelskay 8, Kinelskay 4 and Konstantinovskaya (Erythrospermum). The damage of productive stalks of wheat sawfly larvae was 0.5-1.2%, peaking at an average of weather conditions in 2012, the minimum – in a relatively arid 2014 and depended on the plant population, sawflies favored more sparse crops with a correlation coefficient In 2011, 2012 –0,472- –0.480, –0.734 – in 2014. Under the influence of the sawfly larvae damaged ear stem length was reduced by no more than 5.2, the number of grains per ear – 14.4, the weight of grain in the ear – 14.4, weight of 1000 seeds – 15,2%. The largest decrease in the length of the spike observed in average weather conditions for 2012, the number and grains weight per ear – in a wet 2011, the mass of 1000 grains – in the dry 2014 from wet to dry years, the harmfulness of the sawfly increased from an average to the bottom of the slope. The smallest decrease in all indicators of productivity observed in the upper part of the slope. The number of adults cephus pygmaeus in all parts of the slopes were almost equally low (0.2-0.4 ind./100 net sweeps). The cephus pygmaeus loss of of wheat grain productivity were minor and were 3-35 kg/h.

Anellierte Diamine als nützliche Dikationen am Beispiel der Darstellung von Halocupratsalzen / Anellated Diamines as valuable Dications using the Example of Halocuprate Salts

Diamines such as (R,R)-TMCDA (1) form anellated dications with dihalomethanes, which were obtained in the presence of copper(I)halides as salts containing halocuprate anions. Using the chiral diamine (R,R)-TMCDA (1) and its meso-form cis-TMCDA (2) trichloro- and tribromocuprates with trigonal-planar geometry, and with TMEDA (3) a continuous chain of copper(I)iodid were formed. The crystal structures were discussed and compared in terms of the influence of the dication on the structural behavior of the corresponding anion. Overall we revealed an easy access to chiral or achiral dications which are based on the readily available (R,R)-TMCDA (1) and its isomer cis-TMCDA (2).

Isolation and Structure Determination of Phenazostatin D, a New Phenazine froma Marine Actinomycete Isolate Pseudonocardia sp. B6273

A new phenazine derivative, phenazostatin D (1a), was isolated from an extract of the actinomycete isolate Pseudonocardia sp. B6273 via a TLC-guided chemical screening. The structure of the compound was assigned by spectroscopic methods and found to be the meso-form of phenazostatin B (1b). Phenazostatin D was inactive against the tested bacteria and fungi. The strain also produced the known phenazine antibiotic methyl saphenate (2).

Macrocyclic Ligand Design. Structure—Function Relationships Underlying the Interaction of Substituted Derivatives of Oxygen-Nitrogen Macrocycles with Selected Transition and Post Transition Metal Ions

The effect of methyl substitution on 15- and 17-membered macrocycles (incorporating N2O2- and N3O2-donors, respectively) on their interaction with cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and lead(II) has been investigated. The results are compared with those obtained for the corresponding complexes of the unsubstituted (parent) rings. Binding constants for the formation of the metal complexes have been determined potentiometrically in 95% methanol (I = 0·1; Et4NClO4). An X-ray crystallographic study of [NiL(H2O)] (ClO4)2 (where L is the dimethyl derivative of a 17-membered, N3O2-donor macrocycle) confirms that the nickel ion is six-coordinate, with the complex cation exhibiting a distorted octahedral geometry defined by all five donor atoms of the O2N3-macrocycle (in its meso form) and the oxygen of the water molecule. In this structure the macrocyclic backbone incorporating the N3-donor fragment is arranged facially. Molecular mechanics modelling of this complex predicts that the observed facial configuration will be favoured over an alternative facial arrangement or a meridional one.

Koordinationschemie π-gebundener Cyclopentadienyl-Chalcogeno-Ether, II. Palladium(II)- und Platin(II)-Komplexe von [C5(SMe)5]Mn(CO)3, [C5Cl2(SMe)3]Mn(CO)3 und [C5Cl2(SMe)2(PPh2)]Mn(CO)3./ Coordination Chemistry of π-Bonded Cyclopentadienyl Chalcogeno Ethers, II. Palladium(II) and Platinum(II) Complexes of [C5(SMe)5]Mn(CO)3, [C5Cl2(SMe)3]Mn(CO)3 and [C5Cl2(SMe)2(PPh2)]Mn(CO)3

Treatment of the cymantrene thioether [C5(SMe)5]Mn(CO)3 (IIb) with Na2PdCl4 or K2PtCl4 yields the bimetallic chelate complexes [C5(SMe)5]Mn(CO)3*MCl2 (M = Pd (2) or Pt (3)). Similarly, the S,P-chelate complexes [C5Cl2(SR)2(PPh2)]Mn(CO)3*PdCl2 (R = Me (4a), Ph (4b)) can be obtained from the corresponding mononuclear cymantrene derivatives and Na2PdCl4 or (PhCN)2PdCl2. Analysis of the 1H NMR spectra only allows for the Pt complex the identification of one meso form, which seems to be favoured by 2:1, together with the D,L forms. The crystal structures of [C5Cl2(SMe)3]Mn(CO)3*PdCl2(1, C11H9Cl4MnO3PdS3, triclinic, P1̄, a = 7.617(3) Å , b = 10.528(4) Å ,c = 12.473(5) Å , α = 72.95(3)°, β = 84.94(3)°, γ = 88.75(3)°, V = 952.6(6) Å3, Z = 2), 2 (C13H15Cl2MnO3PdS5, orthorhombic, Pn21/c, a = 12.739(5) Å , b = 9.992(3) Å , c = 16.884(5) Å , V = 2149(1) Å, Z = 4), and 4 (C23H18Cl6MnO3PPdS2, monoclinic, P21/c, a = 13.199(4) Å , b = 29.198(11) Å , c = 15.921(7) , β - 101.41(3)°, V = 6015(4) Å3, Z = 8) are reported and compared with each other and other bimetallic metallocene phosphine and thioether derivatives.

Neuer Syntheseweg und Molekülstruktur von (1,2,3-Triphenyltriphosphan-1,3-diyl)zirkonocen(IV), / A New Synthesis and the Molecular Structure of (1,2,3-Triphenyltriphosphane-1,3-diyl)zirconocene(IV),

Cp2ZrCl2 reacts with an excess of PH2Ph in the presence of magnesium turnings to yield (Cp = η5-C5H5) (1). Only the meso form of 1 is present in solution as well as in the solid state [with R or S configuration of P(1), S or R of P(3)]. 1 crystallizes monoclinicly in the space group P21/c (Nr. 14) with Z = 4, a = 10.699(3), b = 15.065(3), c = 16.135(13) Å, β = 109.53(5)°. The structure was refined to R = 0.066 for 2082 reflections. The coordination of the P3Ph32- ligand to the Cp2Zr fragment is nearly symmetrical (Zr-P: 2.635(2) and 2.622(2) Å), and the ZrP3 metallacycle is almost planar.

The Molecular Geometry of Diastereoisomeric Bis[α-(9-anthryl)ethyl] Ethers

The crystal structures of racemic bis [α-(9-anthryl)] ether and its meso form have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by least squares to residuals of 0.053 and 0.041 for 1868 and 3568 independent 'observed' reflections respectively. Crystals of the racemate are orthorhombic, Pcab, a 23.07(1), b 19.85(2), c 10.241(8) Ǻ, Z 8. Crystals of the meso form are triclinic, Pī , a 19.032(12), b 14.207(11), c 9.451(8) Ǻ, α 79.46(6), β 89.68(6), γ 68.97(5)°, Z 4. In the racemate , the dihedral angle between the methyl groups along the ether bonds is 12°, and the short axes of the anthracene moieties lie at an angle of about 120°. In the meso compound, for the two molecules the dihedral angles between the methyl groups along the ether bonds are 90 and 93°, the angle between the two anthracene moieties is 90°, and the interplanar angles between the partly overlapping aromatic systems are 46 and 43°.

The conformations of tartaric acids in aqueous solution studied by 1H and 13C nuclear magnetic resonance

Vicinal H—H and C—H coupling constants are reported for (+)-tartaric acid and meso-tartaric acid at various pH values and used in a discussion of the conformation of these molecules. This is found not to change much with pH. For the meso form, in particular, the most favoured conformer is determined not so much by the possibility of internai [Formula: see text] hydrogen bonding but, at least in part, by stabilization of polar conformations in a sol vent (H2O) of high dielectric constant.