Abstract A metastable polymorph of Ti 3 Sn (called c-Ti Sn) exhibiting the cubic Cr Si-type structure was prepared by a mechanochemical route. At temperatures about 450 °C, it transforms to well-known hexagonal phase (Ni type, called h-Ti Sn). 0.5% iron incorporated into material originating from steel beaker and balls. However, quantum-chemical calculations show that this should not lead stabi...

In this work UVA and blue light have been used to study photo-isomerisation about the C=C double bond in complexes of the type [PtCl(-CH=CHAr)(tmeda)] [Ar = C6H5, (E)-2a; 4-CH3O-C6H4, (E)-2b; 3-NO2-C6H4, (E)-2c; and 3-CH3O-C6H4, (E)-2d]. The progress of the reaction has been monitored by NMR spectroscopy following irradiation of the NMR sample. The NMR data have been complemented with X-ray dif...

       The volatile constituents of aerial parts of Euphorbia aellenii Rech.f. and E. microsciadea Boiss. were analyzed by gas chromatography (GC) and GC-mass spectrometry (MS) methods. The main volatile constituents of E. aellenii were phytol isomer (47.3%), camphene (31.9%) and caryophyllene oxide (20.6%), while the major volatile components of <em...

Catalytic osmylation of cis and trans 2-cyclohexene-cyclohexanol (1a) and (1b) are carried out in the presence of N-methyl morpholine-N-oxide. Under the same conditions, only the cis isomer reacted, leading to triol (3). The steric hindrance of the equatorial OH group probably prevents the trans isomer from entering into such reaction. Triol (3) was also obtained from the reduction of the d...

Methyl tetra - 0-methyl- ?-D- glucopyranoside is stereoselectively prepared from tetramethyl-D- glucopyranose by using (MeI+NaH) in toluene (86%) or cyclohexane (85%), while its ?- isomer is best synthesized in hexamethyl phosphoramide (64%). Similarly, methyl tetra-o-methyl-?- D-mannopyranoside is synthesized in cyclohexane (80%), while its ?- isomer is predominantly prepared by (MeI+n-Bu...

i The Soret circular dichroism (CD) spectrum of carbonmonoxy myoglobin dtifers strikingly for the two heme isomers: Aqzl =+90 M-’cm-’ for isomer A, AQ21 = -7 M-’cm-’ for isomer B (Aojula et al., BiochemJ. 250, 853(1988)). This observation implies significant differences in the protein conformation andlor distortions of the heme from planarity between the two isomers. Molecular dynamics simulati...

Human haemoglobin was prepared containing [14C]haem in either the aor the fsubunits. Coupled oxidation of such hybrid haemoglobins with ascorbate and 02 showed that the biliverdin produced by the a-subunits contained approx. 55% aisomer and 45% f-isomer, whereas that produced by the fl-subunits contained approx. 75% a-isomer and 25% P-isomer. Coupled oxidation of isolated aand fl-subunits gave ...