Studying Pyrene-Labeled Macromolecules with the Model-Free Analysis

Abstract

The model-free (MF) analysis was applied to the fluorescence decays of 32 pyrene-labeled macromolecules to probe their internal dynamics. Depending on whether a pyrene derivative was attached to the chain ends of a linear chain, randomly along a polymer backbone, or at the chain terminals of dendrimers, the MF analysis was applied to probe the dynamics of polymer ring closure, backbone flexibility, or chain terminal mobility, respectively. For those polymeric constructs whose decays could be fitted according to Birks' scheme or the fluorescence blob model (FBM), good agreement was obtained between the rate constant for excimer formation retrieved from the MF analysis <k(MF)> and those obtained according to the Birks' scheme or FBM analyses. The MF analysis was also applied to conduct the first successful direct comparison of the chain terminal dynamics of two types of pyrene end-labeled dendrons. Finally, the MF analysis was employed to build a calibration curve against which the internal dynamics of any pyrene-labeled macromolecule can now be benchmarked. This study further confirms the versatility and robustness of the MF analysis to study any type of pyrene-labeled macromolecule.

Unusual Fluorescence Behavior of Pyrene-Amine Containing Dendrimers

“…The SPC analysis presented in this work has been done using the Model Free Analysis. [16,22]. It was observed (Table 1) that both dendrons display a similar < k >, having a relevant difference only in the T E0 value, which represents the lifetime of the excimer.…”

“…The reported decays are presented as Log of Counts on y axis and Time in x axis. The analysis of the decays has been carried out following the equation presented in previous work [16,22].…”

“…The most used are the Birks’ scheme, the Fluorescence Blob Model and the Model Free Analysis (MFA). This last method has proved to be very efficient to study the dendrimeric structures in detail [21,22].…”

Self-aggregation of the pyrene labeled poly(acrylic acid) in nanoscopically crowded environments

“…The polymer with a lower Py content experiences a less crowded environment which has therefore a higher polarity. fluorescence decays is typical for macromolecules randomly grafted with Py [17,[49][50][51]. Fig.…”

“…where t M is the natural lifetime of Py monomers than do not form excimer [17,51]. One may suppose that PAAPy forms excimers in RMs with the same rate constant <k>, if t M is not much affected by the w 0 .…”