Effect of Different Conformational Distributions on the Ultrafast Coherence Dynamics in Porphyrin-Based Polymers

The optical and transport properties of biological and artificial multichromophoric functional materials are strongly affected by the disorder and electron-vibration couplings. The conformational disorder in multichromophores becomes critical especially in the control of coherent dynamics. Indeed, microscopic details of the dephasing processes promoted by the disorder are not yet fully clarified. Here we applied 2D electronic spectroscopy to study the dynamics of vibrational coherences in porphyrin-functionalized polymer samples characterized by different conformational disorder. Distinct coherent dephasing behaviors have been found for low-frequency vibrational modes in the studied samples. The experimental results have been interpreted on the basis of molecular dynamics and quantum mechanical calculations, which allowed correlation of the trend in the dephasing times with different conformational distributions in the two polymers.