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

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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 13C 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 UVpump(excitation)–IRpump(perturbation)–IRprobe(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.

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Figure 1: Summary of the multipulse IR-control experiments.
Figure 2: Ground-state infrared absorption properties of 1* in CD2Cl2.
Figure 3: Summary of excited-state dynamics with and without vibrational perturbation in CH2Cl2, with the middle panel showing results for ν(13C) excitation and the right panel for ν(12C) excitation (2,016 and 2,104 cm−1, respectively).
Figure 4: Modelling of the kinetic evolution of the off-diagonal response in IR-control experiments.


  1. 1

    Fleming, G. R. & Ratner, M. A. Grand challenges in basic energy sciences. Phys. Today 61, 28–33 (2008).

  2. 2

    Barbara, P. F., Meyer, T. J. & Ratner, M. A. Contemporary issues in electron transfer research. J. Phys. Chem. 100, 13148–13168 (1996).

  3. 3

    Schrauben, J. N., Dillman, K. L., Beck, W. F. & McCusker, J. K. Vibrational coherence in the excited state dynamics of Cr(acac)3: probing the reaction coordinate for ultrafast intersystem crossing. Chem. Sci. 1, 405–410 (2010).

  4. 4

    Auböck, G. & Chergui, M. Sub-50-fs photoinduced spin crossover in [Fe(bpy)3]2+. Nat. Chem. 7, 629–633 (2015).

  5. 5

    Johnson, P. J. M. et al. Local vibrational coherences drive the primary photochemistry of vision. Nat. Chem. 7, 980–986 (2015).

  6. 6

    Romero, E. et al. Quantum coherence in photosynthesis for efficient solar-energy conversion. Nat. Phys. 10, 676–682 (2014).

  7. 7

    Fuller, F. D. et al. Vibronic coherence in oxygenic photosynthesis. Nat. Chem. 6, 706–711 (2014).

  8. 8

    Oliver, T. A. A. & Fleming, G. R. Following coupled electronic-Nuclear motion through conical intersections in the ultrafast relaxation of β-Apo-8′-carotenal. J. Phys. Chem. B 119, 11428–11441 (2015).

  9. 9

    Tiwari, V., Peters, W. K. & Jonas, D. M. Electronic resonance with anticorrelated pigment vibrations drives photosynthetic energy transfer outside the adiabatic framework. Proc. Natl Acad. Sci. USA 110, 1203–1208 (2013).

  10. 10

    Christensson, N., Kauffmann, H. F., Pullerits, T. & Mančal, T. Origin of long-lived coherences in light-harvesting complexes. J. Phys. Chem. B 116, 7449–7454 (2012).

  11. 11

    Chin, A. W. et al. The role of non-equilibrium vibrational structures in electronic coherence and recoherence in pigment–protein complexes. Nat. Phys. 9, 113–118 (2013).

  12. 12

    Lin, Z. et al. Modulating unimolecular charge transfer by exciting bridge vibrations. J. Am. Chem. Soc. 131, 18060–18062 (2009).

  13. 13

    Yue, Y. et al. Electron transfer rate modulation in a compact Re(I) donor-acceptor complex. Dalton Trans. 44, 8609–8616 (2015).

  14. 14

    Bakulin, A. A. et al. Mode-selective vibrational modulation of charge transport in organic electronic devices. Nat. Commun. 6, 7880 (2015).

  15. 15

    Delor, M. et al. Toward control of electron transfer in donor-acceptor molecules by bond-specific infrared excitation. Science 346, 1492–1495 (2014).

  16. 16

    Delor, M. et al. On the mechanism of vibrational control of light-induced charge transfer in donor–bridge–acceptor assemblies. Nat. Chem. 7, 689–695 (2015).

  17. 17

    Skourtis, S. S., Waldeck, D. H. & Beratan, D. N. Inelastic electron tunneling erases coupling-pathway interferences. J. Phys. Chem. B 108, 15511–15518 (2004).

  18. 18

    Xiao, D., Skourtis, S. S., Rubtsov, I. V . & Beratan, D. N. Turning charge transfer on and off in a molecular interferometer with vibronic pathways. Nano Lett. 9, 1818–1823 (2009).

  19. 19

    Carias, H., Beratan, D. N. & Skourtis, S. S. Floquet analysis for vibronically modulated electron tunneling. J. Phys. Chem. B 115, 5510–5518 (2011).

  20. 20

    Antoniou, P., Ma, Z., Zhang, P., Beratan, D. N. & Skourtis, S. S. Vibrational control of electron-transfer reactions: a feasibility study for the fast coherent transfer regime. Phys. Chem. Chem. Phys. 17, 30854–30866 (2015).

  21. 21

    McGarrah, J. E. & Eisenberg, R. Dyads for photoinduced charge separation based on platinum diimine bis(acetylide) chromophores: synthesis, luminescence and transient absorption studies. Inorg. Chem. 42, 4355–4365 (2003).

  22. 22

    Sazanovich, I. V. et al. Ultrafast photoinduced charge transport in Pt(II) donor–acceptor assembly bearing naphthalimide electron acceptor and phenothiazine electron donor. Phys. Chem. Chem. Phys. 16, 25775–25788 (2014).

  23. 23

    McGarrah, J. E., Hupp, J. T. & Smirnov, S. N. Electron transfer in platinum(II) diimine-centered triads: mechanistic insights from photoinduced transient displacement current measurements. J. Phys. Chem. A 113, 6430–6436 (2009).

  24. 24

    Archer, S. A., Keane, T., Delor, M., Meijer, A. J. H. M. & Weinstein, J. A. 13C or not 13C: selective synthesis of asymmetric carbon-13-labeled platinum(II) cis-Acetylides. Inorg. Chem. 55, 8251–8253 (2016).

  25. 25

    Lipkin, J. S., Song, R., Fenlon, E. E. & Brewer, S. H. Modulating accidental Fermi resonance: what a difference a neutron makes. J. Phys. Chem. Lett. 2, 1672–1676 (2011).

  26. 26

    Hamm, P. & Zanni, M. Concepts and Methods of 2D Infrared Spectroscopy (Cambridge Univ. Press, 2011).

  27. 27

    Glik, E. A. et al. Ultrafast excited state dynamics of Pt(II) chromophores bearing multiple infrared absorbers. Inorg. Chem. 47, 6974–6983 (2008).

  28. 28

    Archer, S. & Weinstein, J. A. Charge-separated excited states in platinum(II) chromophores: photophysics, formation, stabilization and utilization in solar energy conversion. Coord. Chem. Rev. 256, 2530–2561 (2012).

  29. 29

    McCusker, J. K. Femtosecond absorption spectroscopy of transition metal charge-transfer complexes. Acc. Chem. Res. 36, 876–887 (2003).

  30. 30

    Spears, K. G., Wen, X. & Zhang, R. Electron transfer rates from vibrational quantum states. J. Phys. Chem. 100, 10206–10209 (1996).

  31. 31

    Crim, F. F. Bond-selected chemistry: vibrational state control of photodissociation and bimolecular reaction. J. Phys. Chem. 100, 12725–12734 (1996).

  32. 32

    Crim, F. F. Chemical dynamics of vibrationally excited molecules: controlling reactions in gases and on surfaces. Proc. Natl Acad. Sci. USA 105, 12654–12661 (2008).

  33. 33

    Roberts, G. M. et al. Exploring quantum phenomena and vibrational control in σ* mediated photochemistry. Chem. Sci. 4, 993–1001 (2013).

  34. 34

    Nazarov, A. E., Barykov, V. Y. & Ivanov, A. I. Effect of excitation pulse carrier frequency on ultrafast photoinduced charge transfer kinetics: effect of intramolecular high frequency vibrational mode excitation. J. Phys. Chem. C 119, 2989–2995 (2015).

  35. 35

    Delor, M., Sazanovich, I. V., Towrie, M. & Weinstein, J. A. Probing and exploiting the interplay between nuclear and electronic motion in charge transfer processes. Acc. Chem. Res. 48, 1131–1139 (2015).

  36. 36

    Scattergood, P. A. et al. Electron transfer dynamics and excited state branching in a charge-transfer platinum(II) donor-bridge-acceptor assembly. Dalt. Trans. 43, 17677–17693 (2014).

  37. 37

    Kasyanenko, V. M., Lin, Z., Rubtsov, G. I., Donahue, J. P. & Rubtsov, I. V. Energy transport via coordination bonds. J. Chem. Phys. 131, 154508 (2009).

  38. 38

    Rubtsov, I. V. Relaxation-assisted two-dimensional infrared (RA 2DIR) method: accessing distances over 10 Å and measuring bond connectivity patterns. Acc. Chem. Res. 42, 1385–1394 (2009).

  39. 39

    Park, K.-H. et al. Infrared probes based on nitrile-derivatized prolines: thermal insulation effect and enhanced dynamic range. J. Phys. Chem. Lett. 4, 2105–2110 (2013).

  40. 40

    Delor, M. et al. Dynamics of ground and excited state vibrational relaxation and energy transfer in transition metal carbonyls. J. Phys. Chem. B 118, 11781–11791 (2014).

  41. 41

    Fedoseeva, M. et al. Vibrational energy transfer dynamics in ruthenium polypyridine transition metal complexes. Phys. Chem. Chem. Phys. 17, 1688–1696 (2015).

  42. 42

    Dereka, B., Rosspeintner, A., Li, Z., Liska, R. & Vauthey, E. Direct visualization of excited-state symmetry breaking using ultrafast time-resolved infrared spectroscopy. J. Am. Chem. Soc. 138, 4643–4649 (2016).

  43. 43

    Dorfman, K. E., Zhang, Y. & Mukamel, S. Coherent control of long-range photoinduced electron transfer by stimulated X-ray Raman processes. Proc. Natl Acad. Sci. USA 113, 10001–10006 (2016).

  44. 44

    Vogt, G., Nuernberger, P., Brixner, T. & Gerber, G. Femtosecond pump–shaped-dump quantum control of retinal isomerization in bacteriorhodopsin. J. Chem. Phys. Lett. 433, 211–215 (2006).

  45. 45

    Dietzek, B., Bruggemann, B., Pascher, T. & Yartsev, A. Pump-shaped dump optimal control reveals the nuclear reaction pathway of isomerization of a photoexcited cyanine dye. J. Am. Chem. Soc. 129, 13014–13021 (2007).

  46. 46

    Debreczeny, M. P., Svec, W. A., Marsh, E. M. & Wasielewski, M. R. Femtosecond optical control of charge shift within electron donor–acceptor arrays : an approach to molecular switches. J. Am. Chem. Soc. 118, 8174–8175 (1996).

  47. 47

    Greetham, G. et al. ULTRA: a unique instrument for time-resolved spectroscopy. Appl. Spectrosc. 64, 1311–1319 (2010).

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Financial support of the EPSRC, the E-Futures Doctoral Training Centre, the University of Sheffield, and the STFC, including access to beam time, is gratefully acknowledged. We thank A. W. Parker for inspiring discussions, and E. Greenough, G. Farrow, A. Auty, and A. Sadler for help with variable temperature measurements.

Author information

M.D. and J.A.W. conceived the hypothesis; M.D., I.V.S. and J.A.W. designed the experiments; M.D., S.A.A. and I.V.S. conducted the experiments on a set-up built and operated by M.T., G.M.G. and I.V.S.; M.D. analysed the experimental data; S.A.A. synthesized the molecules; T.K. and A.J.H.M.M. performed supporting DFT calculations; M.D. and J.A.W. wrote the paper, with input from all authors.

Correspondence to Milan Delor or Julia A. Weinstein.

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Delor, M., Archer, S., Keane, T. et al. Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation. Nature Chem 9, 1099–1104 (2017) doi:10.1038/nchem.2793

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