Spectroscopic properties of the quasi one-dimensional tetracyanoplatinate(II) compounds

Abstract

Within the last ten years significant advances have been made in the knowledge and interpretation of the physical and chemical properties of organic and inorganic compounds with quasi one-dimensional crystal structures. Among these the Mx[Pt(CN)4] · n H2O compounds (with M = Na, K, Ba, Mg, Eu...) show a series of very unusual properties. These are mainly displayed by the lowest excited states which for most compounds exhibit a strong polarized luminescence. By the choice of the cation M it is possible to position the lowest transition energies within the large range from the near ultraviolet to the red. Further, high pressure application allows a continuous tuning, even down to the near infrared. By temperature variation and the application of high magnetic fields an assignment of the low-energy excited states can be achieved. Two distinctly different types of states are present, delocalized states and localized states (self-trapped excitons). By the occurrence of these different types of states the tetracyanoplatinates(II) represent interesting model systems.