Abstract
A series of covalent ferrocene–BODIPY–fullerene triads with the ferrocene groups conjugated to the BODIPY π-system and the fullerene acceptor linked at the boron hub by a common catecholpyrrolidine bridge were prepared and characterized by 1D and 2D NMR, UV/Vis, steady-state fluorescence spectroscopy, high-resolution mass spectrometry, and, for one of the derivatives, X-ray crystallography. Redox processes of the new compounds were investigated by electrochemical (CV and DPV) methods and spectroelectrochemistry. DFT calculations indicate that the HOMO in all triads was delocalized between ferrocene and BODIPY π-system, the LUMO was always fullerene-centered, and the catechol-centered occupied orbital was close in energy to the HOMO. TDDFT calculations were indicative of the low-energy, low-intensity charge-transfer bands originated from the ferrocene–BODIPY core to fullerene excitation, which explained the similarity of the UV/Vis spectra of the ferrocene–BODIPY dyads and ferrocene–BODIPY–fullerene triads. Photophysical properties of the new triads as well as reference BODIPY–fullerene and ferrocene–BODIPY dyads were investigated by pump-probe spectroscopy in the UV/Vis and NIR spectral regions following selective excitation of the BODIPY-based antenna. Initial charge transfer from the ferrocene to the BODIPY core was shown to outcompete sub-100 fs deactivation of the excited state mediated by the catechol bridge. However, no subsequent electron transfer to the fullerene acceptor was observed. The initial charge separated state relaxes by recombination with a time constant of 150–380 ps.
Original language | English (US) |
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Pages (from-to) | 8401-8414 |
Number of pages | 14 |
Journal | Chemistry - A European Journal |
Volume | 25 |
Issue number | 35 |
DOIs | |
State | Published - Jun 21 2019 |
Bibliographical note
Funding Information:Generous support from the Minnesota Supercomputing Institute, NSERC, CFI, NSF (CHE-1464711), NSF MRI (CHE-0922366 and CHE-1420373) University of Manitoba, and WestGrid Canada to V.N. is greatly appreciated. We also wish to thank Prof. Alex Nazarenko for help with the X-ray structure of (2,3)-3 b. Generous support from the NSF support (DMR-1708177) to D.A.B. is greatly appreciated.
Funding Information:
Generous support from the Minnesota Supercomputing Institute, NSERC, CFI, NSF (CHE-1464711), NSF MRI (CHE-0922366 and CHE-1420373) University of Manitoba, and WestGrid Canada to V.N. is greatly appreciated. We also wish to thank Prof. Alex Nazarenko for help with the X-ray structure of (2,3)-3b. Generous support from the NSF support (DMR-1708177) to D.A.B. is greatly appreciated.
Publisher Copyright:
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Keywords
- BODIPY
- X-ray crystallography
- ferrocene
- fullerene
- ultrafast pump-probe