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Synthesis, Structure, and Photophysical Properties of Blue‐Emitting Zinc(II) Complexes with 3‐Aryl‐Substituted 1‐Pyridylimidazo[1,5‐ a ]pyridine Ligands
Author(s) -
Ardizzoia G. Attilio,
Brenna Stefano,
Durini Sara,
Therrien Bruno,
Veronelli Mattia
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402415
Subject(s) - chemistry , pyridine , denticity , luminescence , zinc , aryl , excited state , quantum yield , photoluminescence , metal , crystallography , fluorescence , stereochemistry , medicinal chemistry , photochemistry , crystal structure , organic chemistry , physics , optics , alkyl , optoelectronics , quantum mechanics , nuclear physics
Abstract Six zinc(II) complexes of the general formula [Zn(L R )X 2 ] ( 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 complexes 1 , 3 , and 4 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 (N py ) and the pyridine‐like nitrogen atom of the imidazo[1,5‐ a ]pyridine group (N im ). 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. Complexes 1 – 3 showed moderate‐to‐good absolute photoluminescence quantum yields (PLQYs) in the solid state with a maximum PLQY of 0.40 for 1 . 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 ZnCl 2 , and a PLQY of 0.29 was recorded for 4 . A possible interpretation of this behavior is reported.