Vibrational coherence transfer in an electronically decoupled molecular dyad

Abstract

The ring opening of a dithienylethene photoswitch incorporated in a bridged boron-dipyrromethene - dithienylethene molecular dyad was investigated with ultrafast spectroscopy. Coherent vibrations in the electronic ground state of the boron-dipyrromethene are triggered after selective photoexcitation of the closed dithienylethene indicating vibrational coupling although the two moieties are electronically isolated. A distribution of short-lived modes and a long-lived mode at 143 cm−1 are observed. Analysis of the theoretical frequency spectrum indicates two modes at 97 cm−1 and 147 cm−1 which strongly modulate the electronic transition energy. Both modes exhibit a characteristic displacement of the bridge suggesting that the mechanical momentum of the initial geometry change after photoexcitation of the dithienylethene is transduced to the boron-dipyrromethene. The relaxation to the dithienylethene electronic ground state is accompanied by significant heat dissipation into the surrounding medium. In the investigated dyad, the boron-dipyrromethene acts as probe for the ultrafast photophysical processes in the dithienylethene.

Ultrafast coherent oscillations reveal a reactive mode in the ring-opening reaction of fulgides

“…S8, ESI †). 46 In the low frequency range, accessible within the time resolution of our experiments, the B80 cm À1 mode causes the largest shift in accord with the experimentally observed coherent oscillation (Fig. 3B).…”

Highly efficient modulation of FRET in an orthogonally arranged BODIPY–DTE dyad

“…The observed TA signals decay nearly completely within the first 20 ps. After the decay of photoexcited BODIPY a clear signature of electronically excited closed DTE as a product of the FRET reaction is not observed because the deactivation of excited closed DTE is very fast in that system (τ = 2.2 ps) 12 preventing its accumulation.…”

“…Promising candidates for the application as photoswitches are dithienylethenes (DTE) because of their reversible photoconversion between a colorless open and a colored closed form, their thermal stability and fatigue resistance 10 . Consequently, DTE has been assembled in molecular dyads or triads in combination with boron-dipyrromethene (BODIPY) 11 12 13 , anthracene 1 2 , oligothiophene 7 14 15 , perylene 16 , porphyrin 8 17 18 , rhodamine 19 , metal complexes 20 and semiconductor quantum dots 21 22 23 . In our recently published work we describe the photomodulation of electronic conjugation within BODIPY-diarylethene molecular dyads 13 .…”

Reversible Photomodulation of Electronic Communication in a π‐Conjugated Photoswitch‐Fluorophore Molecular Dyad

“…Finally,t he DAS at t 3 = 19 ps with its derivative-like shape can be attributed to ac ooling process of the closed isomer after relaxation to the electronic ground state. This behaviori sa lready knownf or other dithienylethene-BODIPY conjugates [34] as well as for individual DAEs. [35] All of these observations lead to the conclusion that in the closed dyad (1-c)t he BODIPY and the DAE are electronically coupled.…”

“…4ps) to the ground state as known for other DAE derivatives [34,35] ( Supporting Information, Figure S6). In the case of the dyad 1-o (gray squares in Figure 4, bottom) the BODIPY moietyi se xcited at 600 nm resulting in av ery long-lived excited state with al ife time of severaln anoseconds (Figure 4, top).…”