Pt2Ag acetylide-doped silica nanoparticles: enabling luminescence of Pt2Ag complexes in water and sensors for highly sensitive detection of cyanide anions

Abstract

Two novel luminescent hetero-trinuclear complexes [Pt₂Ag(μ-dpppy)₂(CCC₆H₄R-4)₄](ClO₄) (R = H, 1; R = CH₃, 2; dpppy = 2,6-bis(diphenylphosphino)pyridine) were synthesized by the self-assembly reaction between [Pt(CCC₆H₄R-4)₄]²⁻ and [Ag₂(μ-dpppy)₃]²⁺ and characterized by elemental analyses, electrospray ionization mass spectrometry, and ¹H NMR and ³¹P{¹H} NMR spectroscopy and by X-ray crystallography for complex 2. Two Pt₂Ag complexes show strong luminescence in the solid state, but exhibit weak emission in CH₂Cl₂ solution and in acetonitrile–water (1 : 1, v : v) solution at room temperature. To overcome the limitations of low water solubility and weak emission in solutions, a new kind of luminescent Pt₂Ag@SiO₂ nanoparticles was prepared by incorporating the new Pt₂Ag acetylides into monodisperse silica nanoparticles. It is noted that Pt₂Ag@SiO₂ nanoparticles exhibit strong luminescence in aqueous solution, and cyanide anions tend to decrease their luminescence intensity in NaHCO₃–NaOH buffer solution. Based on this, a novel nanosensor for highly sensitive detection of cyanide anions was developed in the range of 0.1–10.0 μM.