Carbazole-modified gold(I) complexes with different substituents: Aggregate-induced luminescence change, various solid-state phosphorescence, temperature-dependent phosphorescence, and contrasting mechanoluminochromic characteristics

Three carbazole-containing isocyano-bridged mononuclear gold(I) complexes with different substituents are reported. The complexes display an aggregate luminescence change effect involving a color change from blue to yellow-green. In the solid state, luminogens 1–3 exhibit varying room-temperature phosphorescence involving blue, light yellow, and yellow emissions. In contrast, at 77 K, the gold(I) phosphors 1–3 display stronger (blue-green or yellow-green depending on the phosphor) phosphorescence with longer luminescence lifetimes. In addition, the solid-state phosphorescence of 1–3 is adjusted by moderate mechanical stimulus. More specifically, phosphor 1 shows reversible high-contrast mechanoluminochromic behavior involving interconversion between blue and yellow-green luminescence and phosphor 2 shows reversible mechanoluminochromism phenomenon involving luminescent interconversion between light yellow and light green. In contrast, solid-state phosphor 3 displays an irreversible mechanoluminochromism phenomenon—a strong yellow-green luminescence is observed after grinding. Subsequent treatment with dichloromethane vapor results in a blue-emitting sample.