Luminescence studies in polymers—X

Triplet Energy Migration in Poly(4-methacryloylbenzophenone-co-methyl methacrylate) Films: Temperature Dependence and Chromophore Concentration Dependence

“…David et al . reported the similar concentration effect of 3 BP* for the copolymers of styrene−vinylbenzophenone by phosphorescence decay measurements 2c. The effect was attributed to the increase of triplet energy migration efficiency with the increase of BP content as the result of the large exchange interaction between BP groups.…”

“…This rate constant of k 2 is now represented by the diffusion model proposed by Voltz et al . as follows: ,,,, with where R is the reaction radius of TT annihilation between two 3 BP*, D is the sum of the diffusion coefficients from two 3 BP*, and N is the Avogadro number divided by 10 3 . Substituting eq 5 into eq 4, we get Integration of eq 6 gives with C as a constant where [ 3 BP*] 0 is the initial concentration of 3 BP*.…”

“…Triplet energy migration and the subsequent triplet−triplet (TT) annihilation in polymer systems have been extensively studied through phosphorescence, delayed fluorescence, phosphorescence depolarization, and photochemical reactions . Benzophenone (BP) is a chromophore suitable for the study of triplet energy migration and TT annihilation due to the high quantum efficiency of the intersystem crossing and the well-defined photophysical properties. − …”

Immobilization of enzymes on porous silica supports

“…2). The number of terminal NH2 groups fixed on 1 g of the used silica is about 2 x 10 [16] what means one amino group per square nanometer. Due to large number of active NH2 groups on the silica surface and short length of the glutarddehyde spacer arm, the interaction between the protein and the silica surface is highly probable and of course is expected to be the greatest for the largest immobilized enzyme -urease and may explain the lowering in activity of this enzyme.…”

“…Due to large number of active NH2 groups on the silica surface and short length of the glutarddehyde spacer arm, the interaction between the protein and the silica surface is highly probable and of course is expected to be the greatest for the largest immobilized enzyme -urease and may explain the lowering in activity of this enzyme. We have not yet studied systematically whether there is a strict correlation between the size of the enzyme molecule, its specific activity, the number of its external aminogroups accessible for couplmg and the enzymatic activity of the immobilized enzymes, which factors were reported to be important [16]:…”