Heteroleptic Copper(I) Pseudorotaxanes Incorporating Macrocyclic Phenanthroline Ligands of Different Sizes

Meera Mohankumar, Michel Holler, Eric Meichsner, Jean-François Nierengarten, Frédéric Niess, Jean-Pierre Sauvage, Béatrice Delavaux-Nicot, Enrico Leoni, Filippo Monti, Joanna M. Malicka, Massimo Cocchi, Elisa Bandini, Nicola Armaroli

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Abstract

A series of copper(I) pseudorotaxanes has been prepared from bis[2-(diphenylphosphino)phenyl] ether (POP) and macrocyclic phenanthroline ligands with different ring sizes (m30, m37, and m42). Variable-temperature studies carried out on the resulting [Cu(mXX)(POP)]+(mXX = m30, m37, and m42) derivatives have revealed a dynamic conformational equilibrium due to the folding of the macrocyclic ligand. The absorption and luminescence properties of the pseudorotaxanes have been investigated in CH2Cl2. They exhibit metal-to-ligand charge-transfer emission with photoluminescence quantum yields (PLQYs) in the range 20-30%. The smallest system [Cu(m30)(POP)]+shows minimal differences in spectral shape and position compared to its analogues, suggesting a slightly distorted coordination environment. PLQY is substantially enhanced in poly(methyl methacrylate) films (∼40≈45%). The study of emission spectra and excited-state lifetimes in powder samples as a function of temperature (78-338 K) reveals thermally activated delayed fluorescence, with sizable differences in the singlet-triplet energy gap compared to the reference compound [Cu(dmp)(POP)]+(dmp = 2,9-dimethyl-1,10-phenanthroline) and within the pseudorotaxane series. The system with the largest ring ([Cu(m42)(POP)]+) has been tested as emissive material in OLEDs and affords bright green devices with higher luminance and greater stability compared to [Cu(dmp)(POP)]+, which lacks the macrocyclic ring. This highlights the importance of structural factors in the stability of electroluminescent devices based on Cu(I) materials.
Original languageEnglish
Pages (from-to)2336 - 2347
Number of pages12
JournalJournal of the American Chemical Society
Volume140
Issue number6
DOIs
Publication statusPublished - 14 Feb 2018
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Mohankumar, M., Holler, M., Meichsner, E., Nierengarten, J-F., Niess, F., Sauvage, J-P., Delavaux-Nicot, B., Leoni, E., Monti, F., Malicka, J. M., Cocchi, M., Bandini, E., & Armaroli, N. (2018). Heteroleptic Copper(I) Pseudorotaxanes Incorporating Macrocyclic Phenanthroline Ligands of Different Sizes. Journal of the American Chemical Society, 140(6), 2336 - 2347. https://doi.org/10.1021/jacs.7b12671