Structure and Assignment of the Luminescence of a New Mixed-Ligand Copper(I) Polymer

Abstract

The synthesis and crystal structure of a new copper(I) polymer, [{(Ph3P)2Cu2(μ-Cl)2(μ-pyrazine)}∞], are reported. The polymer is photoluminescent with its emission maximum at 16 340 cm-1 at a temperature of 20 K. The emitting state is assigned with the assistance of excited state distortions determined by using resonance Raman intensities. The polymer consists of (PPh3)(pyz)Cu(μ-Cl2)Cu(pyz)(PPh3) units in which pyrazine ligands bridge copper pairs to form a chain of dimers. The packing arrangement contains two inversion centers. Each dimer has an inversion center between the two coppers and the bridging chlorine atoms. A second inversion center is located in the center of the pyrazine ligand, which links the dimers in an infinite linear chain. The nitrogen atom of the pyrazine, the phosphorus atom of one triphenylphosphine, and the two chlorine atoms form a slightly distorted tetrahedron about the copper. The largest distortions in the lowest excited electronic state, determined from the resonance Raman intensities, occur along totally symmetric modes of the pyrazine ligand. The emission is assigned to copper(I) to pyrazine charge transfer.

A Series of One‐ to Three‐Dimensional Copper Coordination Polymers Based on N‐Heterocyclic Ligands

“…The high-energy transition can be assigned as metal-to-ligand transfer (MLCT: CuǞCN), whereas the low-energy transition may be attributed to intraligand (π-π*) fluorescence in the 5-metta ligands, which is in reasonable agreement with literature examples. [26][27][28] …”

Luminescent Complexes Containing Halogeno-bridged Dicopper(I) Unit {Cu2(µ-X)2} (X = Cl, Br, and I)

“…Among d-transition-metal complexes, emissive d 6 and d 8 complexes, typically ruthenium(II), iridium(III), and platinum(II) complexes, have been studied widely from interest in photophysics and photochemistry, as well as in related applications, such as solar cells, artificial photosynthesis, sensors, and light-emitting devices. 1 Following the development of these studies, research on luminescent d 10 metal complexes, such as gold(I) and copper(I) as well as silver(I) complexes, has been rapidly expanding from the 1990s, because of their strong luminescence at ambient temperatures, characteristic metal metal interactions, and the low cost especially for copper complexes.…”

Synthesis, Characterization, Spectroscopic and Photophysical Properties of New [Cu(NCS){(L‐N)2 or (L′‐NN)}(PPh3)] Complexes (L‐N, L′‐NN = Aromatic Nitrogen Base)

“…For example, a variety of trinuclear Cu pyrazolates [12] exhibiting fascinating optical phenomena and photolumines-cent mixed-ligand copper polymers have been recently reported. [13,14] Copper phosphino and/or pyridine derivatives, [15][16][17][18][19] emissive at room or at low temperature, have been described but attempts to describe the associated spectroscopic properties in terms of known structures of the complexes remain limited. Despite the considerable attention paid to cyclic trinuclear d 10 complexes, a fundamental issue that remains outstanding concerns, for example, the role played by the transition metal in determining the molecular structure, photophysics and spectroscopic properties in mononuclear species.…”