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.
|Number of pages||12|
|Journal||Journal of the American Chemical Society|
|State||Published - 14 Feb 2018|
Bibliographical noteFunding Information:
Financial support by the CNR (PHEEL; Progetto Bandiera NCHEM), the CNRS (PICS no. 6840), the University of Strasbourg, the International Center for Frontier Research in Chemistry, and the LabEx Chimie des Systemes Complexes is gratefully acknowledged.
Financial support by the CNR (PHEEL; Progetto Bandiera NCHEM), the CNRS (PICS no. 6840), the University of Strasbourg, the International Center for Frontier Research in Chemistry, and the LabEx “Chimie des System̀ es Complexes” is gratefully acknowledged. We further thank M. Schmitt for high-field NMR measurements, J.-M. Strub for the mass spectra, and A. Sournia-Saquet (LCC) for electrochemical measurements.
© 2018 American Chemical Society.