Vapoluminescent materials that display reversible and naked eye perceivable colour or luminescence changes have been used as sensors for detection of volatile organic compounds (VOCs) which are toxic air pollutants. This feature article highlights recent advance in finding luminescence vapochromic solid-state materials based on d⁶, d⁸ or d¹⁰ metal complexes. It has been demonstrated that vapour-triggered luminescence colour changes are mostly relevant to a variation of weak interactions such as metal–solvent bonds, metallophilic contacts, π–π stacking, hydrogen bonding, host–guest affinity or reversible isomerization etc.

Incorporation of diplatinum complex Pt₂(μ-dppm)₂(bpyCC)₄ or Pt₂(μ-dppm)₂(phenCC)₄ with Ln(hfac)₃(H₂O)₂ (Ln = Nd, Eu, Yb) gave a series of Pt₂Ln₂ and Pt₂Ln₄ bimetallic arrays, in which the excitation of d(Pt) → π*(R–CC) MLCT absorption induces sensitisation of lanthanide luminescence through efficient d → f energy transfer from Pt^II alkynyl chromophores.