Search

DFT calculations on the full catalytic cycle for manganese catalysed enantioselective hydrogenation of a selection of ketones have been carried out at the PBE0‐D3PCM//RI‐BP86PCM level. Mn complexes of an enantiomerically pure chiral P,N,N ligand have been found to be most reactive when adopting a facial coordination mode. The use of a new ligand with an ortho‐substituted dimethylamino‐pyridine motif has been calculated to completely transform the levels of enantioselectivity possible for the hydrogenation of cyclic ketones relative to the first‐generation Mn catalysts. In silico evaluation of substrates has been used to identify those likely to be reduced with high enantiomer ratios (er), and others that would exhibit less selectivity; good agreements were then found in experiments. Various cyclic ketones and some acetophenone derivatives were hydrogenated with er's up to 99 : 1. [ABSTRACT FROM AUTHOR]

DFT calculations on the full catalytic cycle for manganese catalysed enantioselective hydrogenation of a selection of ketones have been carried out at the PBE0‐D3PCM//RI‐BP86PCM level. Mn complexes of an enantiomerically pure chiral P,N,N ligand have been found to be most reactive when adopting a facial coordination mode. The use of a new ligand with an ortho‐substituted dimethylamino‐pyridine motif has been calculated to completely transform the levels of enantioselectivity possible for the hydrogenation of cyclic ketones relative to the first‐generation Mn catalysts. In silico evaluation of substrates has been used to identify those likely to be reduced with high enantiomer ratios (er), and others that would exhibit less selectivity; good agreements were then found in experiments. Various cyclic ketones and some acetophenone derivatives were hydrogenated with er's up to 99 : 1. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the feasibility to collect off-electronic resonance chiral sum frequency generation (SF6) vibrational spectra from interfacial proteins and peptides at the solid/liquid inter- face in situ. It is difficult to directly detect a chiral SF6 vibrational spectrum from interfacial fibrinogen molecules. By adopting an interference enhancement method, such a chiral SF6 vibrational spectrum can be deduced from interference spectra between the normal achiral spectrum and the chiral spectrum. We found that the chiral SF6 vibrational spectrum of interfacial fibrinogen was mainly contributed by the β-sheet structure. For a β-sheet peptide tachyplesin 1, which may be quite ordered at the solid/liquid interface, chiral SF6 vibrational spectra can be collected directly. We believe that these chiral signals are mainly contributed by electric dipole contributions, which can dominate the chiroptical responses of uniaxial systems. For the first time, to our knowledge, this work indicates that the off-electronic resonance SF6 technique is sensitive enough to collect chiral SFG vibrational spectra of interfacial proteins and peptides, providing more structural information to elucidate interfacial protein and peptide structures. [ABSTRACT FROM AUTHOR]