1,721,066 research outputs found
Struttura molecolare e organizzazione cristallina di complessi di argento a struttura wheel-and-axle
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Diastereomeric half-sandwich Ru(II) cationic complexes containing amino amide ligands. Synthesis, solution properties, crystal structure and catalytic activity in transfer hydrogenation of acetophenone
No full textThe cationic complexes [(g6-arene)Ru(N,O-amino amide)X]Y (arene = p-cymene or indane; N,O-amino
amide = (L)-proline amide or (L)-phenylalanine amide; X = Cl or I; Y = Cl, I or PF6) have been synthesised
and fully characterized by spectroscopic and analytical methods. In several cases (1a, 3a, 4a, 4b, 5) the
metal configuration has been definitively established by X-ray analysis on single crystal. The lability of
the metal center in solution has been studied by 1H NMR and CD techniques. The highest configurational
stability has been found in the complexes of the type [(g6-indane)Ru(N,O-proline amide)Cl]Y (4a,b). The
complexes 1b, 2a–b, 3b, 4b and 5 are good precatalysts for the transfer hydrogenation of acetophenone in
basic i-PrOH, with ee up to 76% at 30 _C. An ESI(+)-MS study of pre-catalytic solutions has provided useful
information on the catalytic mechanism
Photoinduced alkaline pH-jump on the nanosecond time scale
No full textThe triphenylmethane leucohydroxide salt 4-(dimethylamino)-4'-(trimethylammonium) triphenylmethanol iodide has been used as a photoactivatable caged hydroxide to rapidly increase the pH of a neutral aqueous solution on the nanosecond time scale. Photoexcitation of the compound with a nanosecond ultraviolet laser pulse results in the formation of a colored carbocation with a rate greater than 108 s-1; recombination occurs with a multiexponential kinetics. The dissociation is completely reversible on time scales of 102 s and offers a large time window after the pH jump, in which the proton transfer reactions can be studied. The effectiveness of the photodissociation process to increase the pH of the solution has been demonstrated by means of the pH indicator bromoxylenol blue
Synthesis, structure and catalytic behaviour of half-sandwich Ru(II) complexes containing L-prolineamide and L-phenylalanineamide
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Deprotonation yields, pKa, and aci-nitro decay rates in some substituted o-nitrobenzaldehydes
No full textIn this paper we report the deprotonation yields, the pKa, and decay kinetics of the aci-nitro intermediates of some
substituted 2-nitrobenzaldehydes that can be used as photoactivatable caged proton compounds. The decay of the
aci-nitro absorbance for 2-nitrobenzaldehyde occurs within a few nanoseconds from photoexcitation. Addition of
electron donating methoxy substituents at positions 4 and 5 leads to lower deprotonation yields, higher pKa, and
slower decays of the aci-nitro intermediates. On the contrary, the decay rate is accelerated by the introduction of an
electron-withdrawing Cl atom at position 4 in the phenyl ring, with little influence on the deprotonation yield and pKa
of the aci-nitro intermediate
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