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    • Keywords


      Photoisomerization; fluorescence depolarization; uncoiling

    • Abstract


      Dynamics of isomerization and fluorescence depolarization of merocyanine 540 (MC540) in an aqueous solution of polyacrylic acid (PAA) have been studied using picosecond time resolved fluorescence spectroscopy. It is observed that the dynamics of isomerization and depolarization are sensitive enough to monitor the uncoiling of PAA at high pH (> 6). At low pH (< 3), when the polymer remains in a hypercoiled form, polymer bound MC540 experiences very high microscopic friction and, hence, the isomerization and depolarization processes are very slow. At high pH (> 6) a polyanion is formed and the polymer assumes an extended configuration due to electrostatic repulsion. At high pH (> 6), the anionic probe MC540 is expelled from the polyanion to bulk water and the dynamics of isomerization and fluorescence depolarization become faster by 12 and 5 times respectively, compared to those at low pH.

    • Author Affiliations


      Dipankar Sukul1 Sobhan Sen1 Partha Dutta1 Kankan Bhattacharyya1

      1. Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata - 700 032, India
    • Dates

  • Journal of Chemical Sciences | News

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