Synthesis, optical properties, and photoluminescence of organometallic acetylide polymers of platinum functionalized with Si and Ge-bridged bis(3,6-diethynyl-9-butylcarbazole)

A series of light-emitting group 14 element-containing organometallic platinum polyynes of the form trans-[-Pt(PBu3)2C ≡ CArC ≡ C(ER2)C ≡ CArC ≡ C-]n(Ar = 9-butylcarbazole-3,6-diyl, ER2= SiMe2, SiPh2, GeMe2, GePh2) were synthesized and spectroscopically characterized. The solution properties and regiochemical structures of this new structural class of organosilicon- and organogermanium-based metallopolyynes were studied by IR and NMR (1H,13C,29Si, and31P) spectroscopies. The optical absorption and photoluminescence spectra of these metallopolymers were examined and compared with their well-defined dinuclear model complexes trans-[Pt(Ph)(PEt3)2C ≡ CArC ≡ C(ER2)C ≡ CArC ≡ CPt(Ph)(PEt3)2]. The influence of the heavy platinum atom and the group 14 silyl or germyl structural unit possessing different side group substituents on the thermal and phosphorescence properties were investigated in detail. We have also established the goal for studying the evolution of the lowest singlet and triplet excited states with the nature of ER2unit in these metallopolymers. The present work indicates that the phosphorescence emission efficiency harnessed through the heavy-atom effect of platinum in the main chain changes significantly with the identity of ER2in the general orders GeR2> SiR2(R = Me, Ph) and EMe2> EPh2(E = Si, Ge).