Synthesis of a 1,3,5-benzotriazepine-2,4-dione based library

A library of benzotriazepines have been synthesised employing microwave-mediated synthesis, supported resins and parallel synthesis methodology.     

X-Ray Crystallographic Structure and Absolute Configuration of the Cyclic Di-amino Acid Peptide: Cyclo(<Emphasis Type="SmallCaps">l</Emphasis>-HomoCySH-<Emphasis Type="SmallCaps">l</Emphasis>-HomoCySH)

Abstract  

The cyclic di-amino acid peptide cyclo(l-homoCySH-l-homoCySH) [(3S, 6S)-3, 6-bis(2-sulfanylethyl) piperazine-2,5-dione, C₈H₁₄N₂O₂S₂, crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 6.1509(2) ?, b = 18.0217(9) ?, c = 29.6166(14) ?, V = 3283.0(2) ?³, Z = 12 (3 molecules, A, B and C, per asymmetric unit), D _c = 1.422 g cm⁻³ and a linear absorption coefficient of 0.464 mm⁻¹. The crystal structure determination was carried out with MoKα X-ray data measured at 120(2) K. In the final refinement cycle the data/restraints/parameter ratios were 5595/0/385 and goodness-of-fit on F ² = 1.084. Final R indices for [I > 2sigma(I)] were R1 = 0.0746, wR2 = 0.1356 and R indices (all data) R1 = 0.1092, wR2 = 0.1529. The largest electron density difference peak and hole were 0.526 and −0.445e ?⁻³. The DKP rings in all three molecules are essentially, and unusually, planar and the C=O oxygen atoms are co-planar with the ring in each case. Ring atom rms deviations, including the =O groups, are 0.0668, 0.0658 and 0.0656 ? in molecules A, B and C, respectively. Details of the molecular geometry are compared with the compound cyclo(Gly-Gly) (Degeilh R, Marsh RE Acta Cryst 12:1007, 1959) and in addition some cyclic di-amino acid peptides in which the DKP rings have more puckered boat conformations.     

The structural and stereogenic properties of pentaerythritoxy-bridged cyclotriphosphazene derivatives: spiro-spiro, spiro-ansa and ansa-ansa isomers

Reactions of pentaerythritol with hexachlorocyclotriphosphazene, N3P3Cl6, and gem-disubstituted cyclotriphosphazene derivatives, N3P3Cl4R2 [R = Ph, NHBu(t) or (OCH2CF2CF2CH2O)0.5] gave a series of pentaerythritol-bridged derivatives linked spiro-spiro, spiro-ansa and ansa-ansa. The structures and stereogenic properties of the products were characterised by X-ray crystallography and 31P NMR spectroscopy on addition of the chiral solvating agent, (S)-(+)-2,2,2-trifluoro-1-(9-anthryl)ethanol. Molecules with spiro-spiro and spiro-ansa bridged gem-disubstituted cyclophosphazenes [R = Ph, NHBu(t) or (OCH2CF2CF2CH2O)0.5] are found to be chiral and exist as racemates. Molecules with ansa-ansa bridged cyclophosphazenes [R = Cl or (OCH2CF2CF2CH2O)0.5] have been characterised for the first time and are shown to have meso configurations. Analysis of crystal structure data shows that the six-membered chair form of the spiro rings and the eight-membered boat-chair form of the ansa rings in the bridged compounds are similar to analogous spiro and ansa exocyclic ring conformations of 1,3-propanedioxy-derivatives of cyclophosphazenes.     

Phospha(III)guanidinate complexes of titanium(IV) and zirconium(IV) amides

Two procedures for the synthesis of group 4 phosphaguanidine compounds M(R₂PC{NR′}₂)(NR″₂)₃ (M = Ti, Zr; R = Ph, Cy; R′ = ⁱPr, Cy; R″ = Me, Et) are described. Spectroscopic characterization indicated symmetrical bonding of the phosphaguanidinate ligand in solution for the P-diphenyl derivatives whereas the P-dicyclohexyl analogs adopt a more rigid geometry with inequivalent N_amidine substituents within the phosphaguanidinate ligand. X-ray diffraction studies show exclusively monomeric tbp metal centers for a series of derivatives, with a chelating phosphaguanidinate ligand that spans an axial and an equatorial position. Two different conformers have been identified in the solid-state that differ in the relative orientation of the phosphorus R₂P–C substituents with respect to the equatorial plane of the tbp metal. The synthetic protocol was extended to the bimetallic complex, [PhP(C{NⁱPr}₂Ti{NMe₂}₃)CH₂–]₂, which was characterized by crystallography as the meso-form.     

Ti/Ni过渡层对WS2薄膜摩擦学性能影响

采用射频溅射法,通过预先制备Ti和Ni 2种过渡层的工艺在3Cr13马氏体不锈钢基片上制备了硫化钨薄膜,通过与无过渡层的射频溅射WS2薄膜对比,研究了2种过渡层对薄膜性能的影响.3种样品的物相分析,表面形貌观察,微区化学成分测定,膜基结合力和薄膜摩擦系数测试等结果表明,Ti过渡层对硫化钨薄膜结构和S/W原子比没有明显的影响,对膜层的摩擦系数影响也不大,但薄膜耐磨性有所提高.而Ni过渡层虽对S/W原子比无明显影响,但却明显地提高薄膜Ⅱ型织构(基面取向)的强度,从而降低了薄膜的摩擦系数,提高了薄膜耐磨性.     

Deep Red Emitting Heteroleptic Ir(III) Complexes that Incorporate Unsymmetrical 4-quinoline Carboxylic Acid Derived Ligands

Six disubstituted ligands based upon 2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids have been synthesised, solvent-free, in one step from a range of commercially available isatin derivatives. These species behave as ancillary chelating ligands for Ir(III) complexes of the form [Ir(C^N)₂(N^N)]PF₆ (where C^N=cyclometalating ligand; N^N=2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids). An X-ray crystallographic study on one complex shows a distorted octahedral geometry wherein a cis-C,C and trans-N,N coordination mode is observed for the cyclometalating ligands. DFT calculations predicted that variations in N^N ligand from 2,2′-bipyridine to L^{1 – 6} should localise the LUMO on to the Lⁿ ligand and that the complexes are predicted to display MLCT/LLCT character. All complexes displayed luminescence in the deep red part of the visible region (674–679 nm) and emit from triplet states, but with little apparent tuning as a function of L^{1 – 6} . Further time-resolved transient absorption spectroscopy supports the participation of these triplet states to the excited state character.