H-bonding template-directed synthesis of a complete m-PDA-bridged ladder polyhydrosiloxane （OLPHS）

A highly ordered m-phenylenediimino-bridged ladder polyhydrosiloxane (abbr. OLPHS) with Mn = 1.24 104 was synthesized under assistance of H-bonding template constructed from imino H-bonding, N(Si)-H N(Si)-H, via a modified process of stoichiometric hydrolysis and dehydrochlorination condensation reaction between Si–Cl and Si–OH bonds. The complete ladder structure of OLPHS has been confirmed by the following three data. Two characteristic Bragg’s peaks representing the ladder width (w =0:94 nm) and ladder thickness (t = 0.42 nm) were observed in XRD analysis, which are consistent with those cal- culated by molecular simulation. The very sharp absorption with a small half-peak width ew1=2=0:5 ppmT for [(–HN)HSiO2/2]n moiety of OLPHS in 29Si NMR spectrum indicated presence of the complete ladder structure. As collateral evidence, a higher glass transition temperature (Tg = 105 8C) is also recorded in the DSC measurement, implying the high stiffness of ladder chain of OLPHS.     

A spectral study of the interaction between chelerythrine chloride and cytidine

To study the possible anticancer mechanisms of chelerythrine (CHE), and its interactions with cytidine were investigated by UV-vis spectrophotometric and spectrofluorimetric measurements and by thermodynamic calculations. The binding of CHE to cytidine could be characterized by the hypochromic and bathochromic effects in the absorption bands, and the quenching of fluorescence intensity. The spectral data were fit by linear analysis, yielding a binding constant of 2.49×104 L mol-1 at 25℃of CHE and cytidine, and a van't Hoff enthalpy of -20.02 kJ/mol for the exothermic interaction in the standard state. In addition, with