Issue 34, 2022

The effects of introducing terminal alkenyl substituents into the 2,2′-bipyridine domain in [Cu(N^N)(P^P)]+ coordination compounds

Abstract

The N^N chelating ligands 6,6′-bis(but-3-en-1-yl)-2,2′-bipyridine (1), 6-(but-3-en-1-yl)-6′-methyl-2,2′-bipyridine (2), 6,6′-bis(pent-4-en-1-yl)-2,2′-bipyridine (3) and 6-(pent-4-en-1-yl)-6′-methyl-2,2′-bipyridine (4) have been prepared, characterized, and incorporated into the heteroleptic [Cu(N^N)(P^P)][PF6] complexes in which P^P is either POP (bis(2-(diphenylphosphanyl)phenyl)ether) or xantphos (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane). The eight coordination compounds have been fully characterized, including the single crystal structures of [Cu(1)(xantphos)][PF6], [Cu(1)(POP)][PF6]·CH2Cl2, [Cu(2)(xantphos)][PF6], [Cu(2)(POP)][PF6] and [Cu(3)(POP)][PF6]·0.5Et2O. The [Cu(N^N)(P^P)]+ cations exhibit a partially reversible or irreversible Cu+/Cu2+ oxidation at more positive potentials than the benchmark [Cu(bpy)(P^P)]+ and [Cu(Me2bpy)(P^P)]+ complexes consistent with the increase in steric hindrance of the terminal alkenyl substituents. When excited in the region of the metal-to-ligand charge transfer (MLCT) absorption, solutions of the [Cu(N^N)(P^P)][PF6] complexes are weak emitters with λmaxem in the range 565–578 nm. However, powdered samples achieve photoluminescence quantum yields in the range of 28.5 to 62.3%, with the highest PLQY found for [Cu(3)(POP)][PF6] with an excited-state lifetime, τ, of 16.1 μs. For [Cu(3)(POP)][PF6], the excited state lifetime was measured in MeTHF at 293 and 77 K, and the increase in τ from 1.77 to 59.4 μs upon cooling supports thermally activated delayed fluorescence (TADF) at ambient temperatures.

Graphical abstract: The effects of introducing terminal alkenyl substituents into the 2,2′-bipyridine domain in [Cu(N^N)(P^P)]+ coordination compounds

Supplementary files

Article information

Article type
Paper
Submitted
08 Jun 2022
Accepted
29 Jul 2022
First published
12 Aug 2022
This article is Open Access
Creative Commons BY license

Dalton Trans., 2022,51, 13094-13105

The effects of introducing terminal alkenyl substituents into the 2,2′-bipyridine domain in [Cu(N^N)(P^P)]+ coordination compounds

J. Wöhler, M. Meyer, A. Prescimone, C. E. Housecroft and E. C. Constable, Dalton Trans., 2022, 51, 13094 DOI: 10.1039/D2DT01799G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements