Highly Luminescent Linear Complex Arrays of up to Eight Cuprous Centers

Abstract

Linearly arranged metal atoms that are embedded in discrete molecules have fascinated scientists across various disciplines for decades; this is attributed to their potential use in microelectronic devices on a submicroscopic scale. Luminescent oligonuclear Group 11 metal complexes are of particular interest for applications in molecular light-emitting devices. Herein, we describe the synthesis and characterization of a rare, homoleptic, and neutral linearly arranged tetranuclear Cu(I) complex that is helically bent, thus representing a molecular coil in the solid state. This tetracuprous arrangement dimerizes into a unique octanuclear assembly bearing a linear array of six Cu(I) centers with two additional bridging cuprous ions that constitute a central pseudo-rhombic Cu(I) 4 cluster. The crystal structure determinations of both complexes reveal close d(10) ⋅⋅⋅d(10) contacts between all cuprous ions that are adjacent to each other. The dynamic behavior in solution, DFT calculations, and the luminescence properties of these remarkable complexes are also discussed.

Cuprophilic Interactions in and between Molecular Entities

“…Multidentate ligands based on amidinato backbones have been frequently employed to synthesize multinuclear copper(I) complexes. The three tetracopper(I) complexes [Cu 4 {μ 4 ‐κ 4 ‐Me 2 Si(NC(Ph)N‐2,6‐ i Pr 2 C 6 H 3 ) 2 } 2 ] ( 92 ), [Cu 4 (μ 4 ‐κ 4 ‐PAA Dipp ) 2 ] (PAA=pyridylamidoamidinato) ( 93 ), and [Cu 4 {μ 4 ‐κ 4 ‐C 2 H 4 (NC(Ph)N‐2,6‐Me 2 C 6 H 3 ) 2 } 2 ] ( 94 ) supported by amidinate‐based tetradentate ligands are shown in Figure . Complexes 92 and 93 were obtained from the reactions between CuI and the sterically congested dilithiated silyl‐linked bisamidinate and PAA, respectively, whereas 94 was obtained by reacting the ethylene‐tethered bisamidine and [Cu(Mes)] 4 .…”

“…To assemble more than four copper atoms in a linear array was a tough task, as evidenced by the limited examples. Based on the ethylene‐tethered tetradentate bisamidinate, Stollenz and co‐workers reported the octacopper(I) complex 105 obtained through dimerization of the tetracopper(I) complex 94 (Figure ) . The dimeric 105 only existed in the solid state and dissociated into two monomeric tetracopper(I) species 94 in solution.…”

Controlled and Reversible Stepwise Growth of Linear Copper(I) Chains Enabled by Dynamic Ligand Scaffolds

“…[1] Furthermore,o ne-dimensional (1D) assemblies of transition-metal complexes ("molecular wires") are of high interest for molecular microelectronics applications and studying processes of electron transfer in metal chains. However,t ovary the metal chain length, new ligand scaffolds usually need to be synthesized in elaborate processes.C urrently,e xamples of well-defined Cu I chains containing three, [10] four, [9a, 11] or more [12] Cu atoms are still rare.Thea bove methods describe bottom-up syntheses with metal precursors and ligands.T ot he best of our knowledge, examples of dynamic interconversions between linear chains of different nuclearities have not been reported, although examples of reversible interconversions between polynuclear complexes of different geometries are known (e.g., metal clusters involving non-linear metal assemblies). [2b, 3] In addition, Cu I "wires" and clusters of various nuclearities have been shown to have interesting photophysical properties that render them suitable for optoelectronic applications.…”

“…[2b, 3] In addition, Cu I "wires" and clusters of various nuclearities have been shown to have interesting photophysical properties that render them suitable for optoelectronic applications. However,t ovary the metal chain length, new ligand scaffolds usually need to be synthesized in elaborate processes.C urrently,e xamples of well-defined Cu I chains containing three, [10] four, [9a, 11] or more [12] Cu atoms are still rare. [6] Recently,t heoretical studies indicated that multicopper coordination to DNAb ase pairs may improve the conductivity of DNA-based nanowires.…”

“…[8a] Another method that provides better control over the geometry and nuclearity of 1D multimetallic chains is the direct combination of polynucleating multidentate ligands (e.g.,o ligo-a-pyridylamides) with am etal precursor to yield EMACc omplexes in ao ne-step process (see Scheme 1f or some examples). However,t ovary the metal chain length, new ligand scaffolds usually need to be synthesized in elaborate processes.C urrently,e xamples of well-defined Cu I chains containing three, [10] four, [9a, 11] or more [12] Cu atoms are still rare. However,t ovary the metal chain length, new ligand scaffolds usually need to be synthesized in elaborate processes.C urrently,e xamples of well-defined Cu I chains containing three, [10] four, [9a, 11] or more [12] Cu atoms are still rare.…”