Dynamics of Water-Soluble Stilbene Dendrimers upon Photoisomerization

摘要

The energy-releasing process and the conformational dynamics of water-soluble stilbene dendrimers upon photoexcitation are studied by the time-resolved transient grating method.While the energy relaxation and the conformational change are completed within 30 ns for the first generation(W-G1),slower dynamics are observed for the second(W-G2)and the third(W-G3)generations.The enthalpy change by the photoisomerization increases and the dynamics of the conformational change becomes slower with an increase in the generation.The diffusion coefficients(D)of the trans- and cis-forms of W-G2 and W-G3 are almost the same,whereas a slight difference is observed for W-G1.These characteristic features are consistently explained in terms of the electric charges on the dendron surface.