Salen with two aza-crown ether pendants H2L1 and its analogues H2L2--H2L4 were successfully synthesized starting from benzo-10-aza-15-crown-5 (BN15C5) or morpholine. Their structures were characterized by IR, MS, H-1 NMR and elemental analysis, and were confirmed by X-ray diffraction analysis of H2L1. Moreover, the saturated oxygen uptake of their cobalt(II) complexes CoL1-CoL4 in diethyleneglycol dimethyl ether was determined at different temperature. The oxygenation contants ( K-O2) and thermodynamic parameters (DeltaHdegrees and DeltaSdegrees) were calculated. The modulation of O-2-binding capabilities by pendant substituents were investigated as compared with the parent Schiff base complex CoL5 (CoSalen). The results indicate that the dioxygen affinities of CoL have been much more enhanced by aza-crown pendants than that by morpholino pendants, and the O-2-binding capabilities of CoL1 and CoL2 with aza-crown pendants would also be enhanced by adding alkali metal cations.
This paper aims to present some delay-dependent global asymptotic stability criteria for recurrent neural networks with time varying delays. The obtained results have no restriction on the magnitude of derivative of time varying delay, and can be easily checked due to the form of linear matrix inequality. By comparison with some previous results, the obtained results are less conservative. A numerical example is utilized to demonstrate the effectiveness of the obtained results.
The catalytic performance of a series of cobalt(Ⅱ) hydroxamates (CoL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation of p-xylene to p-toluic acid (PTA) were investigated. The results showed that the existing synergistic action in the catalytic oxidation can shorten the induction period of the radical reaction and improve the yield of PTA.
