Synthesis, Structure, and Photophysical Properties of Blue‐Emitting Zinc(II) Complexes with 3‐Aryl‐Substituted 1‐Pyridylimidazo[1, 5‐a]pyridine Ligands. Issue 26 (28th July 2014)

• Record Type: Journal Article
• Authors: Ardizzoia, G. Attilio; Brenna, Stefano; Durini, Sara; Therrien, Bruno; Veronelli, Mattia
• Is Part Of: European journal of inorganic chemistry. Issue 26(2014)
• Page Start: 4310
• Page End: 4319
• Publication Date: 2014-07-28
• Subjects: Luminescence -- Zinc -- N li­gands -- Nitrogen heterocycles; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201402415
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: Six zinc(II) complexes of the general formula [Zn(L R )X2 ] (1 : R = Me, X = Cl;2 : R = Me, X = Br;3 : R = Me, X = I;4 : R = OH, X = Cl;5 : R = OH, X = Br;6 : R = OH, X = I), in which L R is 1‐(pyridin‐2‐yl)‐3‐ o ‐tolylimidazo[1, 5‐ a ]pyridine (L Me ) or 2‐[1‐(pyridin‐2‐yl)imidazo[1, 5‐ a ]pyridin‐3‐yl]phenol (L OH ), have been prepared and characterized. The X‐ray structural analysis performed on complexes1, 3, and4 showed that both L Me and L OH act as N, N ‐bidentate ligands and coordinate to the Zn II metal center through the pyridine ring (Npy ) and the pyridine‐like nitrogen atom of the imidazo[1, 5‐ a ]pyridine group (Nim ). The photophysical properties of these compounds have been investigated, both in solution and in the solid state. The complexes showed intense blue luminescence when excited with UV light ( λ exc = 366–410 nm) with λ max of emission between 440–460 nm in the solid state. Complexes1 –3 showed moderate‐to‐good absolute photoluminescence quantum yields (PLQYs) in the solid state with a maximum PLQY of 0.40 for1 . These values were slightly lower than the PLQY of free L Me (0.60). On the other hand, the PLQY of L OH increased after coordination to ZnCl2, and a PLQY of 0.29 was recorded for4 . A possible interpretation of this behavior is reported. Abstract : Zinc(II) complexes containing N, N ‐bidentate 3‐aryl‐substituted 1‐pyridylimidazo[1, 5‐ a ]pyridine ligands show blue emission in the solid state with absolute photoluminescent quantum yields ( Φ PL ) of up to 0.40. The different emission properties of the complexes are related to the presence of intermolecular O–H··· N hydrogen bonds.