Zinc Tetracyanoplatinate: A Reversible Luminescence‐Based Ammonia Sensor

Abstract

ZnPt(CN)4 was shown to be an effective material for ammonia sensing, and can be synthesized using either solution or mechanochemical methods. A combination of luminescence and Raman spectroscopy revealed that multiple species are involved in the reaction between ammonia and ZnPt(CN)4. The crystal structure of one of these species, Zn(NH3)2Zn(NH3)3(Pt(CN)4)2, was elucidated. Detection of ammonia vapor down to 50 ppm in air was accomplished by monitoring the luminescence spectrum. The reaction between ZnPt(CN)4 and ammonia vapor is reversible, and can be cycled multiple times by either flowing air over the material or heating. ZnPt(CN)4 also has a relatively high thermal stability, decomposing only when heated above 420 °C.

Coordination Geometry Changes in Amorphous Cyanide-Bridged Metal–Organic Frameworks upon Water Adsorption

“…Metal–organic frameworks (MOFs) constructed by metal ions and bridging organic ligands are modern materials − exhibiting various physical properties such as magnetism, − conductivity, − catalysis, − and luminescence − integrated with porous properties. The structural diversity of MOFs arises from the designability of their crystal structures, where rational syntheses can be achieved by changing the metal ion species and introducing substituents onto the ligands. − Cyanide-bridged MOFs consisting of cyanometallates are advantageous for rational design because various metal ions can be combined with cyanometallates, thereby providing versatile functional platforms such as Prussian blue-type and Hofmann-type compounds. − …”

Crystal structure of [K(18-crown-6)]+2[Pt(CN)4]2−

“…While photomagnetic effects have been predominantly realized with hexaand octacyanometallates (Ohkoshi et al, 2012), studies on tetracyanoplatinates and their derivatives have focused on the high electrical conductivities of mixed-valent Krogmann's salts K 2 [Pt(CN) 4 ]Br 0.32 Á2.6H 2 O (Krogmann, 1969), vapochromic sensor materials (e.g. Zn[Pt(CN) 4 ] for ammonia (Varju et al, 2019) and spin-crossover compounds such as [Fe(pyrazine)][Pt(CN) 4 ]Á2H 2 O (Niel et al, 2001). However, alkali salts of polycyanometallates are in generally watersoluble but suffer from insolubility in organic solvents.…”

Guest-Tunable Excited States in a Cyanide-Bridged Luminescent Coordination Polymer

“…For example, charge transfer is one way to tune the emission energy in the ligand-based luminescence of CPs. − Conversely, they often limit the guest molecules to aromatic compounds. Alternatively, metal-centered (MC) emission, such as d–s, d–p, d–d, and f–f transitions, have attracted attention for sensing applications. − Particularly, the metallophilic interaction of Pt­(II), Au­(I), and Cu­(I) complexes provides a shift in emission energy when the metal–metal distance is modulated by guest coordination or accommodation. − In addition, changing the aggregation state of Ir­(III) complex molecules achieved efficient vapor sensing activities for organic solvents . A ligand exchange reaction is another choice to change the emission color significantly by altering their emission origins .…”