Ultrafast Electronic Energy Transfer Beyond the Weak Coupling Limit in a Proximal but Orthogonal Molecular Dyad

Hedley, Gordon J.; Ruseckas, Arvydas; Benniston, Andrew C.; Harriman, Anthony; Samuel, Ifor D. W.

doi:10.1021/acs.jpca.5b08640

Cited by 24 publications

(32 citation statements)

References 39 publications

(70 reference statements)

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“…The absolute absorption of T4 is in good agreement with experiment, the absolute absorption for BOD is slightly too low compared to experiment as the broadening is slightly overestimated. 15 Overall, the absorption for the two peaks of BODT4 is dominated by the absorption of the corresponding building blocks. It remains similar in shape and is slightly red-shifted.…”

Section: 47mentioning

confidence: 97%

“…15 In this system with orthogonal orientation between acceptor and donor unit and strong electronic coupling, simplified models as discussed above are not applicable to understand the origin or characteristics of the EET following photoexcitation. In our experiments, the ultrafast molecular dynamics following excitation is analyzed based on time-resolved fluorescence depolarization, a powerful tool to understand relaxation processes in molecular systems.…”

Section: -13mentioning

confidence: 99%

“…15 However, calculating the absorption for an optimized geometry and using the same homogeneous broadening (in energy) for each electronic transition as in Fig. 1 narrower.…”

Section: 47mentioning

confidence: 99%

“…15 To obtain comparable results from NA-AIMD simulations a swarm of trajectories for a set of initial conditions is considered and propa- fluorescence de-polarization of 120 fs for BODT4 in cyclohexane solution. 15 We note that the prediction of actual time constants is known to be quite sensitive to the method employed for electronic structure calculations. 33 Furthermore, no coupling to the environment was included.…”

Section: 47mentioning

confidence: 99%

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Ultrafast Electronic Energy Transfer in an Orthogonal Molecular Dyad

Wiebeler

Plasser

Hedley

et al. 2017

J. Phys. Chem. Lett.

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Understanding electronic energy transfer (EET) is an important ingredient in the development of artificial photosynthetic systems and photovoltaic technologies. Although EET is at the heart of these applications and crucially influences their light-harvesting efficiency, the nature of EET over short distances for covalently bound donor and acceptor units is often not well understood. Here we investigate EET in an orthogonal molecular dyad (BODT4), in which simple models fail to explain the very origin of EET. On the basis of nonadiabatic ab initio molecular dynamics calculations and ultrafast fluorescence experiments, we gain detailed microscopic insights into the ultrafast electrovibrational dynamics following photoexcitation. Our analysis offers molecular-level insights into these processes and reveals that it takes place on time scales ≲100 fs and occurs through an intermediate charge-transfer state.

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Section: 47mentioning

confidence: 97%

Section: -13mentioning

confidence: 99%

“…15 However, calculating the absorption for an optimized geometry and using the same homogeneous broadening (in energy) for each electronic transition as in Fig. 1 narrower.…”

Section: 47mentioning

confidence: 99%

Section: 47mentioning

confidence: 99%

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Ultrafast Electronic Energy Transfer in an Orthogonal Molecular Dyad

Wiebeler

Plasser

Hedley

et al. 2017

J. Phys. Chem. Lett.

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“…Taking the shorter of the two lifetimes as reflecting the bulk molecules, we can estimate that, on average, 50 % of the excitons will undergo at least 400 hops before returning to the ground state whereas 10 % will make at least 1,400 hops. Of course, any such migration will be incoherent and it should be stressed that the Coulombic mechanism usually underestimates the hopping time at very short separations . The mean time needed for an exciton to cross between stacks is 50±8 ps.…”

Section: Resultsmentioning

confidence: 87%

Exciton Migration and Surface Trapping for a Photonic Crystal Displaying Charge‐Recombination Fluorescence

Al-Aqar

Atahan

Benniston

et al. 2016

Chemistry A European J

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A compact donor-acceptor molecular dyad has been synthesized by attaching an N,N-dimethylamino fragment to a naphthalic anhydride residue. The dyad shows fluorescence from an intramolecular charge-transfer state (i.e., charge-recombination fluorescence) in solution, with the photo-physical properties being strongly dependent on the solvent polarity. Similar emission is seen for single crystals of the target compound, the molecules being aligned head-to-head, although time-resolved emission profiles display dual-exponential kinetics. A second polymorph with the head-to-tail alignment also gives rise to two lifetimes that differ somewhat from those of the first structure, which are assigned to bulk and surface-bound molecules. Growing the crystal in the presence of Rhodamine B localizes the dye around the surface. Excitation of the crystal is followed by sub-ps exciton migration along the aligned stacks, with occasional crossing to adjacent stacks and trapping at the surface. Rhodamine B present at very low levels acts as the acceptor for excitons entering the surface layer. Crystals embedded in a polyester resin form an artificial light-harvesting antenna able to sensitize an amorphous silicon solar cell.

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Bichromophoric Compounds with Orthogonally and Parallelly Arranged Chromophores Separated by Rigid Spacers

Meineke

Bossi

et al. 2017

Chemistry A European J

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Electronic energy transfer (EET) between chromophores is of fundamental importance for many biological processes and optoelectronic devices. However, common models fall short in fully describing the process, especially in bichromophoric model systems with a donor and acceptor connected by a rigid linker providing perpendicular geometries. Herein, we report a novel strategy for preparing bichromophores containing adamantane or 2-(2-adamantylidene)adamantane as rigid spacers, providing a fixed distance between chromophores, and their parallel or perpendicular arrangement without chromophore rotation. New fluorophores were developed and linked via spiroatoms. Bichromophores with identical (blue-blue) or different (blue-red) chromophores were synthesized, either in orthogonal or parallel geometry. These were characterized by absorption/fluorescence spectroscopy, time-resolved fluorescence anisotropy, and fluorescence antibunching measurements. Based on the Förster point-dipole approximation, EET efficiencies were estimated by using geometrical parameters from (time-dependent) density functional calculations. For bichromophores with parallel geometry, the predicted EET efficiencies were near unity and fit the measurements. In spite of estimated values around 0.4 and 0.5, 100 % efficiency was observed also for bichromophores with orthogonal geometry. The new rigid scaffolds presented here open new possibilities for the synthesis of bichormophores with well-defined parallel or perpendicular geometry.

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Ultrafast Electronic Energy Transfer Beyond the Weak Coupling Limit in a Proximal but Orthogonal Molecular Dyad

Cited by 24 publications

References 39 publications

Ultrafast Electronic Energy Transfer in an Orthogonal Molecular Dyad

Ultrafast Electronic Energy Transfer in an Orthogonal Molecular Dyad

Exciton Migration and Surface Trapping for a Photonic Crystal Displaying Charge‐Recombination Fluorescence

Bichromophoric Compounds with Orthogonally and Parallelly Arranged Chromophores Separated by Rigid Spacers

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