Recoverable and Sensitive Pressure-Induced Mechanochromic Photoluminescence of a Au-P Complex

A binuclear Au-P complex [Au₂(2-bdppmapy)₂](PF₆)₂ (1) was synthesised by the reaction of 2-bdppmapy (N,N'-bis-(diphenylphosphanylmethyl-2-aminopyridine) with AuCN and [Cu(MeCN)₄]PF₆. The solid phase of 1 emitted bright yellow phosphorescence at λ_max = 580 nm under UV excitation (QY = 4.41%, τ = 1.88 μs), which shifted to green (λ_max = 551 nm, QY = 5.73%) after being pressurised under 5 MPa. This colour change was recoverable upon exposure to CH₂Cl₂ vapor. Similar mechanochromic photoluminescence behaviour was observed after grinding the crystals of 1. A filter paper impregnated with 1 demonstrated recyclable write/erase functionality for encrypted information transfer.