Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Manganese(i) complexes with metal-to-ligand charge transfer luminescence and photoreactivity


Precious metal complexes with the d6 valence electron configuration often exhibit luminescent metal-to-ligand charge transfer (MLCT) excited states, which form the basis for many applications in lighting, sensing, solar cells and synthetic photochemistry. Iron(ii) has received much attention as a possible Earth-abundant alternative, but to date no iron(ii) complex has been reported to show MLCT emission upon continuous-wave excitation. Manganese(i) has the same electron configuration as that of iron(ii), but until now has typically been overlooked in the search for cheap MLCT luminophores. Here we report that isocyanide chelate ligands give access to air-stable manganese(i) complexes that exhibit MLCT luminescence in solution at room temperature. These compounds were successfully used as photosensitizers for energy- and electron-transfer reactions and were shown to promote the photoisomerization of trans-stilbene. The observable electron transfer photoreactivity occurred from the emissive MLCT state, whereas the triplet energy transfer photoreactivity originated from a ligand-centred 3ππ* state.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Molecular structures of the ligands and complexes (isolated as PF6 salts) explored in this work.
Fig. 2: Steady-state absorption and emission spectroscopy.
Fig. 3: Time-resolved and (spectro-)electrochemical data for [Mn(Ltri)2]+.
Fig. 4: Dual emission at 77 K, different excited states and their photo-reactivities.
Fig. 5: Photoinduced energy and electron transfer.

Data availability

All pertinent experimental procedures, materials, methods and characterization data (NMR spectroscopy, electrospray ionization mass spectrometry, X-ray diffraction, as well as optical spectroscopic and electrochemical data) are provided in this article and its Supplementary Information. Crystallographic data for [ZnCl2(Lbi)·0.5C2H4Cl2] have been deposited at the Cambridge Crystallographic Data Centre under deposition number CCDC 2047767. Copies of data can be obtained free of charge from Source data are provided with this paper.


  1. Costa, R. D. et al. Luminescent ionic transition-metal complexes for light-emitting electrochemical cells. Angew. Chem. Int. Ed. 51, 8178–8211 (2012).

    Article  CAS  Google Scholar 

  2. Hagfeldt, A., Boschloo, G., Sun, L. C., Kloo, L. & Pettersson, H. Dye-sensitized solar cells. Chem. Rev. 110, 6595–6663 (2010).

    Article  CAS  PubMed  Google Scholar 

  3. Twilton, J. et al. The merger of transition metal and photocatalysis. Nat. Rev. Chem. 1, 0052 (2017).

    Article  CAS  Google Scholar 

  4. Magnuson, A. et al. Biomimetic and microbial approaches to solar fuel generation. Acc. Chem. Res. 42, 1899–1909 (2009).

    Article  CAS  PubMed  Google Scholar 

  5. Heinemann, F., Karges, J. & Gasser, G. Critical overview of the use of Ru(ii) polypyridyl complexes as photosensitizers in one-photon and two-photon photodynamic therapy. Acc. Chem. Res. 50, 2727–2736 (2017).

    Article  CAS  PubMed  Google Scholar 

  6. McCusker, J. K. Electronic structure in the transition metal block and its implications for light harvesting. Science 363, 484–488 (2019).

    Article  CAS  PubMed  Google Scholar 

  7. Liu, Y. Z., Persson, P., Sundström, V. & Wärnmark, K. Fe N-heterocyclic carbene complexes as promising photosensitizers. Acc. Chem. Res. 49, 1477–1485 (2016).

    Article  CAS  PubMed  Google Scholar 

  8. Zhang, W. K. et al. Tracking excited-state charge and spin dynamics in iron coordination complexes. Nature 509, 345–348 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Auböck, G. & Chergui, M. Sub-50-fs photoinduced spin crossover in Fe(bpy)32+. Nat. Chem. 7, 629–633 (2015).

    Article  PubMed  CAS  Google Scholar 

  10. Carey, M. C., Adelman, S. L. & McCusker, J. K. Insights into the excited state dynamics of Fe(ii) polypyridyl complexes from variable-temperature ultrafast spectroscopy. Chem. Sci. 10, 134–144 (2019).

    Article  CAS  PubMed  Google Scholar 

  11. Zhang, K., Ash, R., Girolami, G. S. & Vura-Weis, J. Tracking the metal-centered triplet in photoinduced spin crossover of Fe(phen)32+ with tabletop femtosecond M-edge X-ray absorption near-edge structure spectroscopy. J. Am. Chem. Soc. 141, 17180–17188 (2019).

    Article  CAS  PubMed  Google Scholar 

  12. Chábera, P. et al. Feii hexa N-heterocyclic carbene complex with a 528 ps metal-to-ligand charge-transfer excited-state lifetime. J. Phys. Chem. Lett. 9, 459–463 (2018).

    Article  PubMed  CAS  Google Scholar 

  13. Braun, J. D. et al. Iron(ii) coordination complexes with panchromatic absorption and nanosecond charge-transfer excited state lifetimes. Nat. Chem. 11, 1144–1150 (2019).

    Article  CAS  PubMed  Google Scholar 

  14. Duchanois, T. et al. NHC-based iron sensitizers for DSSCs. Inorganics 6, 63 (2018).

    Article  CAS  Google Scholar 

  15. Förster, C. & Heinze, K. Photophysics and photochemistry with earth-abundant metals—fundamentals and concepts. Chem. Soc. Rev. 49, 1057–1070 (2020).

    Article  PubMed  Google Scholar 

  16. Chábera, P. et al. A low-spin Feiii complex with 100-ps ligand-to-metal charge transfer photoluminescence. Nature 543, 695–699 (2017).

    Article  PubMed  CAS  Google Scholar 

  17. Kjær, K. S. et al. Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime. Science 363, 249–253 (2019).

    Article  PubMed  CAS  Google Scholar 

  18. Wood, C. J. et al. A comprehensive comparison of dye-sensitized NiO photocathodes for solar energy conversion. Phys. Chem. Chem. Phys. 18, 10727–10738 (2016).

    Article  CAS  PubMed  Google Scholar 

  19. Young, E. R. & Oldacre, A. Iron hits the mark. Science 363, 225–226 (2019).

    Article  CAS  PubMed  Google Scholar 

  20. Büldt, L. A., Guo, X., Vogel, R., Prescimone, A. & Wenger, O. S. A tris(diisocyanide)chromium(0) complex is a luminescent analog of Fe(2,2′-bipyridine)32+. J. Am. Chem. Soc. 139, 985–992 (2017).

    Article  PubMed  CAS  Google Scholar 

  21. Mann, K. R. et al. Electronic structures and spectra of hexakisphenylisocyanide complexes of Cr0, Mo0, W0, Mni, and Mnii. Inorg. Chim. Acta 16, 97–101 (1976).

    Article  CAS  Google Scholar 

  22. Plummer, D. T. & Angelici, R. J. Synthesis and characterization of homoleptic complexes of the chelating bidentate isocyano ligand tert-BuDiNC. Inorg. Chem. 22, 4063–4070 (1983).

    Article  CAS  Google Scholar 

  23. Treichel, P. M., Firsich, D. W. & Essenmacher, G. P. Manganese(i) and chromium(0) complexes of phenyl isocyanide. Inorg. Chem. 18, 2405–2409 (1979).

    Article  CAS  Google Scholar 

  24. Hamze, R. et al. Eliminating nonradiative decay in Cui emitters: >99% quantum efficiency and microsecond lifetime. Science 363, 601–606 (2019).

    Article  CAS  PubMed  Google Scholar 

  25. Hossain, A., Bhattacharyya, A. & Reiser, O. Copper’s rapid ascent in visible-light photoredox catalysis. Science 364, 450–461 (2019).

    Article  CAS  Google Scholar 

  26. Di, D. W. et al. High-performance light-emitting diodes based on carbene–metal–amides. Science 356, 159–163 (2017).

    Article  CAS  PubMed  Google Scholar 

  27. Gernert, M. et al. Cyclic (amino)(aryl)carbenes enter the field of chromophore ligands: expanded π system leads to unusually deep red emitting Cui compounds. J. Am. Chem. Soc. 142, 8897–8909 (2020).

    Article  CAS  PubMed  Google Scholar 

  28. Liu, W. P. & Ackermann, L. Manganese-catalyzed C–H activation. ACS Catal. 6, 3743–3752 (2016).

    Article  CAS  Google Scholar 

  29. Elangovan, S. et al. Efficient and selective N-alkylation of amines with alcohols catalysed by manganese pincer complexes. Nat. Commun. 7, 8 (2016).

    Article  CAS  Google Scholar 

  30. Mukherjee, A. et al. Manganese-catalyzed environmentally benign dehydrogenative coupling of alcohols and amines to form aldimines and H2: a catalytic and mechanistic study. J. Am. Chem. Soc. 138, 4298–4301 (2016).

    Article  CAS  PubMed  Google Scholar 

  31. Sampson, M. D. et al. Manganese catalysts with bulky bipyridine ligands for the electrocatalytic reduction of carbon dioxide: eliminating dimerization and altering catalysis. J. Am. Chem. Soc. 136, 5460–5471 (2014).

    Article  CAS  PubMed  Google Scholar 

  32. Bourrez, M., Molton, F., Chardon-Noblat, S. & Deronzier, A. Mn(bipyridyl)(CO)3Br: an abundant metal carbonyl complex as efficient electrocatalyst for CO2 reduction. Angew. Chem. Int. Ed. 50, 9903–9906 (2011).

    Article  CAS  Google Scholar 

  33. Henke, W. C., Otolski, C. J., Moore, W. N. G., Elles, C. G. & Blakemore, J. D. Ultrafast spectroscopy of [Mn(CO)3] complexes: tuning the kinetics of light-driven CO release and solvent binding. Inorg. Chem. 59, 2178–2187 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Zhang, Y. et al. Delayed fluorescence from a zirconium(iv) photosensitizer with ligand-to-metal charge-transfer excited states. Nat. Chem. 12, 345–352 (2020).

    Article  CAS  PubMed  Google Scholar 

  35. Pal, A. K., Li, C. F., Hanan, G. S. & Zysman-Colman, E. Blue-emissive cobalt(iii) complexes and their use in the photocatalytic trifluoromethylation of polycyclic aromatic hydrocarbons. Angew. Chem. Int. Ed. 57, 8027–8031 (2018).

    Article  CAS  Google Scholar 

  36. Harris, J. P. et al. Near-infrared 2Eg → 4A2g and visible LMCT luminescence from a molecular bis-(tris(carbene)borate) manganese(IV) complex. Can. J. Chem. 95, 547–552 (2017).

    Article  CAS  Google Scholar 

  37. Drance, M. J. et al. Terminal coordination of diatomic boron monofluoride to iron. Science 363, 1203–1205 (2019).

    Article  CAS  PubMed  Google Scholar 

  38. Sattler, W., Henling, L. M., Winkler, J. R. & Gray, H. B. Bespoke photoreductants: tungsten arylisocyanides. J. Am. Chem. Soc. 137, 1198–1205 (2015).

    Article  CAS  PubMed  Google Scholar 

  39. Mann, K. R., Gray, H. B. & Hammond, G. S. Excited-state reactivity patterns of hexakisarylisocyano complexes of chromium(0), molybdenum(0), and tungsten(0). J. Am. Chem. Soc. 99, 306–307 (1977).

    Article  CAS  Google Scholar 

  40. Herr, P., Glaser, F., Büldt, L. A., Larsen, C. B. & Wenger, O. S. Long-lived, strongly emissive, and highly reducing excited states in Mo(0) complexes with chelating isocyanides. J. Am. Chem. Soc. 141, 14394–14402 (2019).

    Article  CAS  PubMed  Google Scholar 

  41. Harris, R. K. & Mann, B. E. NMR and the Periodic Table (Academic, 1978).

  42. Brown, A. M., McCusker, C. E. & McCusker, J. K. Spectroelectrochemical identification of charge-transfer excited states in transition metal-based polypyridyl complexes. Dalton Trans. 43, 17635–17646 (2014).

    Article  CAS  PubMed  Google Scholar 

  43. Gawelda, W. et al. Ultrafast nonadiabatic dynamics of Feii(bpy)32+ in solution. J. Am. Chem. Soc. 129, 8199–8206 (2007).

    Article  CAS  PubMed  Google Scholar 

  44. Murtaza, Z. et al. Energy-transfer in the inverted region—calculation of relative rate constants by emission spectral fitting. J. Phys. Chem. 98, 10504–10513 (1994).

    Article  CAS  Google Scholar 

  45. Baba, A. I., Shaw, J. R., Simon, J. A., Thummel, R. P. & Schmehl, R. H. The photophysical behavior of d6 complexes having nearly isoenergetic MLCT and ligand localized excited states. Coord. Chem. Rev. 171, 43–59 (1998).

    Article  CAS  Google Scholar 

  46. Taffarel, E., Chirayil, S., Kim, W. Y., Thummel, R. P. & Schmehl, R. H. Coexistence of ligand localized and MLCT excited states in a 2-(2′-pyridyl)benzo[g]quinoline complex of ruthenium(ii). Inorg. Chem. 35, 2127–2131 (1996).

    Article  CAS  Google Scholar 

  47. Anne, A., Hapiot, P., Moiroux, J., Neta, P. & Savéant, J. M. Oxidation of 10-methylacridan, a synthetic analog of NADH, and deprotonation of its cation radical—convergent application of laser flash-photolysis and direct and redox catalyzed electrochemistry to the kinetics of deprotonation of the cation radical. J. Phys. Chem. 95, 2370–2377 (1991).

    Article  CAS  Google Scholar 

  48. Singh-Rachford, T. N. & Castellano, F. N. Photon upconversion based on sensitized triplet–triplet annihilation. Coord. Chem. Rev. 254, 2560–2573 (2010).

    Article  CAS  Google Scholar 

  49. Strieth-Kalthoff, F., James, M. J., Teders, M., Pitzer, L. & Glorius, F. Energy transfer catalysis mediated by visible light: principles, applications, directions. Chem. Soc. Rev. 47, 7190–7202 (2018).

    Article  CAS  PubMed  Google Scholar 

  50. Kvapilova, H. et al. Electronic excited states of tungsten(0) arylisocyanides. Inorg. Chem. 54, 8518–8528 (2015).

    Article  CAS  PubMed  Google Scholar 

  51. Arias-Rotondo, D. M. & McCusker, J. K. The photophysics of photoredox catalysis: a roadmap for catalyst design. Chem. Soc. Rev. 45, 5803–5820 (2016).

    Article  CAS  PubMed  Google Scholar 

  52. Dorn, M. et al. A vanadium(iii) complex with blue and NIR-II spin–flip luminescence in solution. J. Am. Chem. Soc. 142, 7947–7955 (2020).

    Article  CAS  PubMed  Google Scholar 

Download references


O.S.W. thanks the Swiss National Science Foundation (grant nos 200021_178760 and 206021_157687) for financial support. C.K. acknowledges a Novartis University of Basel Excellence Scholarship for Life Sciences.

Author information

Authors and Affiliations



P.H. carried out the synthetic, spectroscopic and electrochemical work and analysed data, C.K. provided guidance in the spectroscopic work, designed the photochemical studies and helped in data analysis, C.B.L. provided guidance in the synthetic, spectroscopic and electrochemical work, D.H. performed the NMR studies and O.S.W. conceived the project and provided guidance. All the authors contributed to the writing and editing of the manuscript and gave approval to its final version.

Corresponding author

Correspondence to Oliver S. Wenger.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Chemistry thanks the anonymous reviewers for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

NMR spectroscopy, electrospray ionization mass spectrometry, X-ray diffraction, as well as optical spectroscopic and electrochemical data; Supplementary Schemes 1 and 2, Figs. 1–56 and references 1–23.

Supplementary Data

Crystallographic data for [ZnCl2(Lbi)·0.5C2H4Cl2], CCDC 2047767.

Source data

Source Data Fig. 2

UV-vis absorption and luminescence spectra.

Source Data Fig. 3

UV-vis transient absorption, time-resolved emission, cyclic voltammetry and spectro-electrochemistry data.

Source Data Fig. 4

UV-vis absorption, luminescence and excitation spectra.

Source Data Fig. 5

UV-vis transient absorption and time-resolved luminescence data.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Herr, P., Kerzig, C., Larsen, C.B. et al. Manganese(i) complexes with metal-to-ligand charge transfer luminescence and photoreactivity. Nat. Chem. 13, 956–962 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing