The Effect of ω-Substituted Acceptors in 4-Dimethylamino-trans-Styrenes on the Polarity in the Ground and Excited Singlet State
ABSTRACT The electric dipole moment in the ground (μg) and in the first excited singlet state (μe) of co-substituted acceptors in 4-dimethylamino-trans-styrenes (Z = P(S)Ph2 , P(O)Ph2 , SO2CH3 ) were determined by solvatochromic and thermochromic methods. The obtained values of μe and μg and the values for Z = CN and Z = NO 2 known from the literature [2] fulfill the linear relation between the dipole moments (μe or μg and the Hammett constants σp of the substituents. On pincreasing the electron-acceptor power of Z, μe grows faster than μg
Viscosity independence of the ratio of fluorescence lifetimes and quantum yields of ω-substituted 4- dimethylamino-trans-styrenes
Abstract The fluorescence lifetimes τ and quantum yields φ F of 4-dimethylamino-ω-diphenylphosphinyl- trans -styrene ( 2a ) and 4-dimethylamino-ω-methylsulphonyl- trans -styrene ( 3a ) were measured in n -paraffins ( n = 6 to n = 16) at 293 K. The ratio τ/φ F was found to be viscosity independent and equal to the radiative lifetime τ 0 ′ calculated from the integrated absorption spectrum. The strong fluorescence quenching and the shortening of the lifetime τ when reducing the viscosity are due to twisting around the double bond, resulting in trans-cis isomerization.
Glycogen phosphorylase in lobster hepatopancreas: action of proteases on the enzyme
Abstract 1. 1. In lobster hepatopancreas, extracellular protreases cause the inactivation of glycogen phosphorylase. 2. 2. The proteolysis of glycogen phosphorylase purified from rabbit muscle by these proteases has been shown by SDS-polyacrylamide gel electrophoresis. 3. 3. A cell isolation technique has allowed us to remove proteases of extracellular digestion and to measure glycogen phosphorylase activity in lobster hepatopancreas. 4. 4. The glycogen phosphorylase activity seems to be mainly associated with R cells while it could not be detected in B cells.