Photoluminescence of Ag(I) complexes with square-planar coordination geometry: the first observation
The first observation of luminescence from Ag(I) complexes with square-planar geometry of the metal is reported. [Ag(Py3PO)2]ClO4 and [Ag(Py3PO)2]OTf – first examples of the emissive square-planar Ag(I) complexes – have been synthesized by reaction of tris(2-pyridyl)phosphine oxide (Py3PO) with the Ag(I) salts. Both complexes exhibit pronounced photoluminescence in the solid state at ambient temperature with nano- and microsecond lifetime components. Remarkably, the luminescence of the complexes has a reversible thermochromic behavior, changing their emission color from yellow (λ □(em¦max) ~ 585 nm) at room temperature to red-orange (λ □(em¦max) = 620 nm) at 77 K. The spectroscopic and computational results reveal that emission of title compounds can be assigned to the 3MLCT phosphorescence with admixture of the 1MLCT fluorescence.