10.1021/jp5066902.s001 Raj Kumar Koninti Raj Kumar Koninti Krishna Gavvala Krishna Gavvala Abhigyan Sengupta Abhigyan Sengupta Partha Hazra Partha Hazra Excited State Proton Transfer Dynamics of Topotecan Inside Biomimicking Nanocavity American Chemical Society 2015 spectrum Excited State Proton Transfer Dynamics state proton transfer RM state cationic form molecule emission Topotecan TPT ESPT dynamics OH bulk state zwitterionic form 2015-02-12 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Excited_State_Proton_Transfer_Dynamics_of_Topotecan_Inside_Biomimicking_Nanocavity/2196652 The excited state proton transfer (ESPT) dynamics of a potentially important anticancer drug, Topotecan (TPT), has been explored in aqueous reverse micelle (RM) using steady-state and time-resolved fluorescence measurements. Both the time-resolved emission spectrum and time-resolved area normalized emission spectrum infer the generation of excited state zwitterionic form of TPT from the excited state cationic form of TPT, as a result of ESPT process from the −OH group of TPT to the nearby water molecule. The ESPT dynamics were found to be severely retarded inside the nanocavities of RMs, yielding time constants of 250 ps to 1.0 ns, which is significantly slower than the dynamics obtained in bulk water (32 ps). The observed slow ESPT dynamics in RM compared to bulk water is mainly attributed to the sluggish hydrogen-bonded network dynamics of water molecules inside the nanocavity of RM and the screening of the sodium ions present at the interface.