Spectroelectrochemical and Theoretical Study of [Si(ttpy) 2 ](PF 6 ) 4 : A Potential Polychromatic Electrochromic Dye

Complexes consisting of earth-abundant main group metals such as silicon with polypyridine ligands are of interest for a variety of optical and electronic applications including as electrochromic colorants. Previous spectroelectrochemical studies with tris(2,2'-bipyridyl)silicon(IV) hexafluorophosphate, [Si(bpy) ](PF ) demonstrated an ability to control the color saturation of the potential electrochromic dye, with the intensity of the dye's green color increasing as the charge state sequentially reduces from 4+ to 1+. In this study, the synthesis of bis(4'-(4-tolyl)-2,2':6',2″-terpyridine)silicon(IV) hexafluorophosphate, [Si(ttpy) ](PF ) , is reported along with electrochemical and spectroelectrochemical analyses. Computational modeling (density functional theory) is used to further elucidate the electrochromic properties of previously reported Si(bpy) species and the new Si(ttpy) species. While the homoleptic tris(bidentate)silicon(IV) complexes are attractive as electrochromic dyes for tunable color saturation, the bis(tridentate)silicon(IV) complexes are attractive as polychromatic electrochromic dyes.