So Close, Yet so Different: How One Donor Atom Changes Significantly the Photophysical Properties of Mononuclear Cu(I) Complexes

Abstract

The manipulation of the photophysical properties of molecular emitters can be realized by composing the close environment of the metal center with the “heavier pnictogen atom” effect. Replacing a nitrogen atom with a heavier phosphorus atom in otherwise isostructural molecular systems results in a significant change of the photophysical parameters. Herein, we report on the synthesis of four pairs of novel phosphinine-based and isostructural diimine-based Cu­(I) complexes, which feature peculiar photophysical properties, and show how these parameters depend on the “heavier pnictogen atom” effect. The obtained Cu­(I) complexes show triplet luminescence with MLCT character, which was investigated by means of spectroscopic and computational methods. It has been found that the photophysical properties of the coordination compounds show a dependency on the rigidity of the ancillary phosphine ligand in an unexpected manner. Replacing the nitrogen atom with a heavier phosphorus atom in otherwise isostructural molecular systems results in a significant change in emission energy and especially in the lifetime of the excited state. The results obtained demonstrate an efficient approach to the design of emissive molecular materials, which allows the construction of luminescent complexes with controlled photophysical properties.

Photoactive Copper Complexes: Properties and Applications

“…In addition to the steric effect brought by substituents close to copper, remote substituents have also been shown to have an effect, as highlighted by the studies of a series of heteroleptic complexes built upon Xantphos ( PP 4 ) as the diphosphine and various substituted 5-phenyl-bipyridines and a series of heteroleptic complexes built upon DPEphos ( PP 1 ) or Xantphos ( PP 4 ) in combination with 2,2′-bipyridines possessing one or two unconjugated alkenes at their 6 and 6′ positions . Moreover, replacing a nitrogen atom in the diimine ligand by a phosphorous atom significantly changes the photophysical properties of the resulting complexes, as nicely highlighted in a systematic study recently reported . Four-coordinate copper­(I) complexes bearing neutral diimine and anionic β-diketiminate ligands have been shown to be promising due to an easy tuning of the HOMO−LUMO gap and the corresponding charge-transfer absorption band that can be independently and systematically controlled via ligand modification .…”

Noncovalent Chelation by Halogen Bonding in the Design of Metal-Containing Arrays: Assembly of Double σ-Hole Donating Halolium with CuI-Containing O,O-Donors

“…The phenomenon of the system stabilization via supramolecular chelation can be utilized for the synthesis of highly labile species such as air-sensitive metal-organic compounds, particularly, copper­(I) derivatives. Since Cu I -based metal complexes are widely used in catalysis of important chemical transformations, − construction of luminescent materials, − and design of antitumor agents, , novel approaches improving their stability are in high demand.…”

A family of CuI-based 1D polymers showing colorful short-lived TADF and phosphorescence induced by photo- and X-ray irradiation

“…Currently, a diverse range of C-, N-, P-, As-, and S-based ligands are utilized for the preparation of emissive Cu(I) complexes. [1][2][3][4][5][6][7][8][9][10][11][12][24][25][26][27][28][29][30] Among them, N-heteroarylphosphines (foremost, pyridylphosphines) have gained great attention as very efficient and versatile 1,3-P,N-ligands for the construction of Cu(I) emitters. [30][31][32][33][34] The presence of π-acceptor N-heterocyclic units in these ligands ensures the generation of MLCT excited states, and coordination of a strong σ-donating P atom to Cu(I) additionally facilitates the MLCT effect and enhances the structural stability.…”