The complex [Ru(Cp)(R,R-BIPHOP-F)(acetone)][SbF(6)], (R,R)-1 a, was used as catalyst for asymmetric Diels-Alder reactions between dienes (cyclopentadiene, methylcyclopentadiene, isoprene, 2,3-dimethylbutadiene) and alpha,beta-unsaturated ketones (methyl vinyl ketone (MVK), ethyl vinyl ketone, divinyl ketone, alpha-bromovinyl methyl ketone and alpha-chlorovinyl methyl ketone). The cycloaddition products were obtained in yields of 50-90 % and with enantioselectivities up to 96 % ee. Ethyl vinyl ketone, divinyl ketone and the halogenated vinyl ketones worked best and their reactions with acyclic dienes consistently provided products with >90 % ee. alpha-Chlorovinyl methyl ketone performed better than alpha-bromovinyl methyl ketone. The reaction also provided a [4.3.1]bicyclic ring system in 95 % ee through an intramolecular cycloaddition reaction. Crystal structure determinations of [Ru(Cp)((S,S)-BIPHOP-F)(mvk)][SbF(6)], (S,S)-1 b, and [Ru(Cp)((R,R)-Me(4)BIPHOP-F)(acrolein)][SbF(6)], (R,R)-2 b, provided the basis for a rationalization of the asymmetric induction.
Biomedical polymers that are designed to degrade faster at slightly acidic pH values may potentially be developed for use in drug delivery, pharmaceutical formulation and regenerative medicine. Water-soluble polyacetals derived from two well known pendent functionalised tyrosine-based diphenol monomers were prepared. Acid catalysed copolymerisation of triethylene glycol divinyl ether with the diphenol was first used to confirm the 1 H-NMR signals for the acetal moieties. A ter-polymerisation process employing the divinyl ether and the diphenol with poly(ethylene glycol) (PEG, 3 400 g mol 21 ) gave the desired water-soluble polyacetals with weight average molecular weights ranging from 24 000-71 000 g mol 21 (PDI 1.6-2.9). Diphenol incorporation into the polymer mainchain was less efficient than aliphatic hydroxyl incorporation from PEG. Thermal properties positively correlated with the relative amount of PEG that was incorporated into the polymer mainchain. The ter-polyacetals displayed enhanced rates of hydrolysis at pH 5.5 with little hydrolysis occurring at pH 7.4 over a 4 day period. Degradation was faster overall than that observed for polyacetals derived from aliphatic monomers only. Air-water contact measurements were lower for the ter-polyacetals than for PEG alone. Overall the properties of the ter-polyacetals were influenced more by the characteristics of PEG in the polymer mainchain than the structure of the two pendent chains that were examined.
Polymeric Cu(I) precursors which deposit metallic Cu films via thermally induced disproportionation
have been investigated as inks for copper direct-write to address deposit haloing, a problem when
monomeric CVD precursor are ink-jetted. Cu(hfac) was complexed to poly(methylvinylsiloxane) and
poly(divinylsiloxane) and these novel precursor compounds were fully characterized by spectroscopic
and thermal techniques and their ability to deposit Cu films was assessed. The polysiloxanes precursors
did deposit metallic Cu films, which partitioned from the polysiloxane residues. Detailed particle induced
X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) data analysis provided valuable
insight into the various stages of the deposition process. The mechanistic insight will be useful in the
development of higher performing metal precursor inks.
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