Resonance energy transfer (RET) describes a process where energy is transferred from an excited molecule, called the energy donor (D), to an acceptor molecule (A). In this research we investigate Förster RET for a pair of dyes linked to a calixarene scaffold. In such systems the relative orientation of the D and A changes on a time-scale comparable to RET dynamics, making the two two limiting regimes, static and dynamic hardly applicable. We here propose an advanced multiscale approach to the dynamics of resonant energy transfer (RET) is presented, combining DFT and TD-DFT results on the energy donor (D) and acceptor (A) moieties with an extensive equilibrium and non-equilibrium molecular dynamics (MD) analysis of a bound D–A pair in solution to build a coarse-grained kinetic model. We demonstrate that a thorough MD study is needed to properly address RET: the enormous configuration space visited by the system cannot be reliably sampled accounting only for a few representative configurations. Moreover, the conformational motion of the RET pair, occurring in a similar time scale as the RET process itself, leads to a sizable increase of the overall process efficiency. This work solved a major issue related to the characterization of RET rates in systems with high flexibility, emphasizing the importance of a dynamical approach for the description of complex decay mechanisms and opening up new opportunities for their theoretical treatment.

Förster resonance energy transfer through the lens of molecular dynamics

ACS Spring Meeting 2021

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