Synthesis and characterization of luminescent zinc(II) complexes with a N,N-bidentate 1-pyridylimidazo[1,5-a]pyridine ligand

Ligand 2-(1-(pyridin-2-yl)imidazo[1,5-a]pyridin-3-yl)phenol (L) has been reacted in a 2:1 molar ratio with different Zn(Y)2nH2O salts, where Y represents a polyatomic anion (Y = ClO4−, NO3−, BF4−, PF6−). The X-ray structural analysis performed on two of the derivatives obtained, namely [Zn(L)2(ClO4)](ClO4)·H2O (1) and [Zn(L)2(CH3CN)2](BF4)2 (6), proves that as expected ligand L binds in a N,N-bidentate mode via the pyridine ring (Npy) and the pyridine-like nitrogen of the imidazo[1,5-a]pyridine skeleton (Nim). A spectroscopic investigation (including infrared, elemental analysis, 1H and 31P NMR, thermogravimetric analysis) has been performed on these species, allowing complete characterizations. A preliminary survey on their photophysical properties in the solid state was carried out: the complexes showing intense luminescence when excited with UV light (λexc = 421–469 nm) with λmax of emission in the blue-green range (468–500 nm) and moderate absolute photoluminescence quantum yields (PLQYs).

Graphical abstractZinc(II) complexes with the N,N-bidentate 2-(1-(pyridin-2-yl)imidazo[1,5-a]pyridin-3-yl)phenol ligand (L) and different polyatomic anions (ClO4−, BF4−, PF6−, NO3−) have been synthesized and spectroscopically characterized. In the solid state, these compounds show intense luminescence with λmax of emission in the blue-green range and moderate absolute photoluminescence quantum yields.Figure optionsDownload full-size imageDownload as PowerPoint slide