Energy transport via coordination bonds

Kasyanenko, Valeriy M.; Lin, Zhiwei; Рубцов, Г.; Donahue, James P.; Rubtsov, Igor V.

doi:10.1063/1.3246862

Cited by 44 publications

(65 citation statements)

References 54 publications

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“…The (ω NN , ω NN , ω CO ) pulse sequence was used in the 2DIR measurements with heterodyning at the ω CO frequencies. The delays between the three pulses, the dephasing time τ and the waiting-time T, and the delay between the third-order signal and the local oscillator, t, were controlled with interferometric precision of <0.05 fs (10). The energies of each of the IR pulses interacting with the sample were ca.…”

Section: Discussionmentioning

confidence: 99%

“…The 2DIR measurements were performed using a dual-frequency three-pulse photon echo method with heterodyned detection (10,34,35). The (ω NN , ω NN , ω CO ) pulse sequence was used in the 2DIR measurements with heterodyning at the ω CO frequencies.…”

Section: Discussionmentioning

confidence: 99%

“…Diffusive energy transport was observed in many molecular systems including 3 10 helices of different sizes with vibrational (22) and electronic (23) initial excitation and a range of model compounds (6,8,10,24,25). Ballistic energy transport in long-chain stretched hydrocarbons exposed to ca.…”

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confidence: 99%

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Constant-speed vibrational signaling along polyethyleneglycol chain up to 60-Å distance

Lin

Rubtsov

2012

Proc. Natl. Acad. Sci. U.S.A.

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A series of azido-PEG-succinimide ester oligomers with a number of repeating PEG units of 0,4,8, and 12 (azPEG0,4,8,and 12) was investigated using a relaxation-assisted two-dimensional infrared (RA 2DIR) spectroscopy method. The RA 2DIR method relies on the energy transport in molecules and is capable of correlating the frequencies of vibrational modes separated by large throughbond distances. Excitation of the azido group in the compounds at ca. 2,100 cm −1 generates an excess energy which propagates in the molecule as well as dissipates into the solvent. We discovered that a part of the excess energy propagates ballistically via the covalent backbone of the molecules with a constant speed of ca. 550 m∕s. The transport is described as a propagation of a vibrational wavepacket having a mean-free-path length of 10-15 Å. The discovery has the potential for developing new efficient signal transduction strategies for molecular electronics and biochemistry. It also permits extending the distances accessible in RA 2DIR structural measurements up to ca. 60 Å. U nderstanding the energy transport dynamics on a molecular scale is vital for a variety of fields including molecular electronics, nanoscience, and biochemistry. A fast developing molecular electronic field utilizes signaling based on charge transport in molecular assemblies; it is conceivable that signaling mechanisms based on energy transduction could be useful if molecular systems featuring efficient energy transport are discovered. Efficient energy dissipation is important for devices of different dimensions ranging from molecular scale-for example, molecular junctions (1)-to macroscopic, such as, for example, optical limiters. Chemical reactions, including charge transfer processes can be influenced substantially by the excess vibrational energy; understanding of the energy transport properties can lead to a control of such reactions (2). Two-dimensional infrared (2DIR) spectroscopy (3-5), in particular the relaxation-assisted 2DIR (RA 2DIR) method (6-8), permits measuring energy transport on a molecular scale. The method relies on the energy transport from the initially excited vibrational mode to the probed mode (a reporter mode); the excess energy transferred to the vicinity of the reporter mode causes a change of its frequency, which results in appearance of the RA 2DIR cross-peak (Fig. 1). Efficient energy transport via covalent bonds resulting in large cross-peak enhancements was observed for the through-bond distances of up to 23 Å (9). The energy transport between ligands in transition-metal complexes has been shown to be efficient as well, demonstrating a 27-fold cross-peak amplification using RA 2DIR (10-12).The energy transport via strong bonds, covalent, coordination, etc., is the dominant energy transport channel at the early time delays after excitation (Fig. 1B). The energy transport to the solvent (13-15) and between the solvent molecules completes the thermal equilibration in the system (Fig. 1C). For example, thermal equilibration in the sa...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Constant-speed vibrational signaling along polyethyleneglycol chain up to 60-Å distance

Lin

Rubtsov

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…Nevertheless, the application of vibrational excitation to manipulate photo-induced reactions in the condensed phase is challenging due to the expected rapid intramolecular vibrational redistribution (IVR). The latter promptly (typically on the scale of a few femtoseconds to a few picoseconds) 17 scrambles memory of vibrational excitation as excited modes are typically strongly anharmonically coupled to other intramolecular modes, resulting in non-selective delocalized excitation 8,18 .However, under the right conditions, namely sufficient energetic and spatial separation from other intramolecular vibrations, certain modes can retain their vibrational excitation for significant periods of time [19][20][21] . ET can take place during or prior to vibrational relaxation of such modes, and it has been shown that the resulting rate of reaction can be greatly influenced by the vibrational state of the reactant 22-24 .…”

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confidence: 98%

On the mechanism of vibrational control of light-induced charge transfer in donor–bridge–acceptor assemblies

et al. 2015

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Nuclear-electronic (vibronic) coupling is increasingly recognized as a mechanism of major importance in controlling the light-induced function of molecular systems. It was recently shown that infrared light excitation of intramolecular vibrations can radically change the efficiency of electron transfer, a fundamental chemical process. We now extend and generalize the understanding of this phenomenon by probing and perturbing vibronic coupling in several molecules in solution. In the experiments an ultrafast electronic-vibrational pulse sequence is applied to a range of donor-bridge-acceptor Pt(II) trans-acetylide assemblies, for which infrared excitation of selected bridge vibrations during ultraviolet-initiated charge separation alters the yields of light-induced product states. The experiments, augmented by quantum chemical calculations, reveal a complex combination of vibronic mechanisms responsible for the observed changes in electron transfer rates and pathways. The study raises new fundamental questions about the function of vibrational processes immediately following charge transfer photoexcitation, and highlights the molecular features necessary for external vibronic control of excited-state processes.

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“…Another important component in our system is the metal centre which acts as a vibrational energy transfer bottleneck that contributes to the localization of injected quanta of energy on either arm of the molecule. [38][39][40][41][42] Furthermore, the presence of the metal offering a two-step charge-separation process starting from a metal-to-acceptor charge transfer followed by reductive quenching from the donor is a particularly effective design strategy to achieve IR-control: 15,16,35,36 it allows the rapid population of a far-fromequilibrium gateway state where an IR pump can be introduced, and in this way perturb an otherwise symmetrical system in a spatially selective manner at a crucial crossroad where small structural and energetic fluctuations dictate the chosen electronic pathway. 43 Complementary to such excited state evolution is the ability to delay the control pulse with respect to actinic excitation, thus influencing reactivity at the decisive moments of light-induced molecular function [44][45][46][47] and circumventing the myriad of processes occurring immediately after electronic excitation, which would rapidly scramble the selectivity of mode-specific excitation.…”

Section: Control Of Et Pathways Using Targeted Vibrational Excitationmentioning

confidence: 99%

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

et al. 2017

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Ultrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer Donor-Bridge-Acceptor-Bridge-Donor "fork" system: asymmetric 13 C isotopic labelling of one of the two -C≡C-bridges makes the two parallel and otherwise identical Donor→Acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UV pump (excitation)-IR pump (perturbation)-IR probe (monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron-transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices. Main TextControlling the function of future advanced materials demands a profound understanding of energymatter interactions in molecular systems at the quantum level. 1 There is a growing consensus that energy-and electron-transfer processes occurring far away from equilibrium in condensed-phase systems on femto-to-picosecond timescales do not conform to the Born-Oppenheimer approximation. Indeed, nuclear and electronic wave functions often strongly interact with each other, leading to exotic phenomena whereby vibrational motion can mediate and dictate the rate and efficiency of electronic transitions. [2][3][4][5] With overwhelming evidence that nuclear-electronic (vibronic) interactions play a crucial role in a broad range of systems, including light harvesting and conversion in photosynthetic organisms, 6-11 this phenomenon represents a tremendous opportunity to acquire deeper knowledge and control over the structural traits that govern molecular function and reactivity.Recent efforts led by Rubtsov et al.,12,13 Bakulin et al., 14 and our group 15,16 have shown that one way to experimentally exploit vibronic coupling to modulate molecular function is to introduce targeted vibrational excitation along specific reaction co-ordinates using ultrafast mid-infrared (IR) pulses. This approach enables promoting or suppressing electronic transitions, notably photo-induced electron transfer (ET), an elementary process that pervades the natural world. Although the demonstrated excited state modulations have been remarkably efficient, up to 100% suppression in one case, 15 predictive and directive control of electron transfer in the condensed phase has not been achieved yet.

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Energy transport via coordination bonds

Cited by 44 publications

References 54 publications

Constant-speed vibrational signaling along polyethyleneglycol chain up to 60-Å distance

Constant-speed vibrational signaling along polyethyleneglycol chain up to 60-Å distance

On the mechanism of vibrational control of light-induced charge transfer in donor–bridge–acceptor assemblies

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

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