Self-Assembled Encapsulation of CuX₂^– (X = Br, Cl) in a Gold Phosphine Box-like Cavity with Metallophilic Au–Cu Interactions

Abstract

Synthetic routes to the crystallization of two new box-like complexes, [Au6(Triphos)4(CuBr2)](OTf)5·(CH2Cl2)3·(CH3OH)3·(H2O)4 (1) and [Au6(Triphos)4 (CuCl2)](PF6)5·(CH2Cl2)4 (2) (triphos = bis(2-diphenylphosphinoethyl)phenylphosphine), have been developed. The two centrosymmetric cationic complexes have been structurally characterized through single-crystal X-ray diffraction and shown to contain a CuX2 – (X = Br or Cl) unit suspended between two Au(I) centers without the involvement of bridging ligands. These colorless crystals display green luminescence (λem = 527 nm) for (1) and teal luminescence (λem = 464 nm) for (2). Computational results document the metallophilic interactions that are involved in positioning the Cu(I) center between the two Au(I) ions and in the luminescence.

Large and Tunable Wavelength Blue Shifts in Luminescent Piezochromism of Cu(I) Complexes via a Guest Encapsulation Strategy

“…Luminescent d 10 Cu­(I) complexes display diverse electronic transitions, such as MLCT, halogen-to-ligand charge transfer (XLCT), cluster-centered (CC) transition, metal-centered (MC) transition, etc., − and are known for the multistimuli-responsive nature, including thermochromism, vapochromism, , and piezochromism. − The mixed transition of MLCT and XLCT (M/XLCT) is common in luminescent Cu­(I) halide complexes. , For the luminescence originated from such mixed transitions, the increase of MLCT excited state for the low-energy emission is inclined to bring red-shifted luminescence, while the increase of XLCT excited state for the high-energy emission trends is likely to result in blue-shifted luminescence. − …”