Manifestation of π–π Stacking Interactions in Luminescence Properties and Energy Transfer in Aromatically-Derived Tb, Eu and Gd Tris(pyrazolyl)borate Complexes

• Published in: Inorganic chemistry 2015-04, Vol.54 (7), p.3125-3133
• Main Authors: Mikhalyova, Elena A, Yakovenko, Anastasiya V, Zeller, Matthias, Kiskin, Mikhail A, Kolomzarov, Yuriy V, Eremenko, Igor L, Addison, Anthony W, Pavlishchuk, Vitaly V
• Format: Article
• Language: English
• Subjects: Borates - chemistry; Coordination Complexes - chemical synthesis; Coordination Complexes - chemistry; Energy Transfer; Erbium - chemistry; Gadolinium - chemistry; Lanthanoid Series Elements - chemistry; Luminescence; Molecular Structure; Pyrazoles - chemistry; Terbium - chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic502120g

The three new complexes TpPyLn­(CH3CO2)2(H2O) (Ln = Eu (1), Gd­(2), or Tb (3)) were prepared and characterized crystallographically. In the crystal lattices of these complexes, separate molecules are connected in infinite chains by π-stacking interactions. Complexes 1 and 3 display intense photoluminescence and triboluminescence (red and green respectively), while compound 3 exhibits electroluminescence commencing at 9 V in an ITO/PVK/3/Al device (ITO = indium-tin oxide, PVK = poly­(N-vinylcarbazole)). A series of Eu/Tb-doped Gd compounds was prepared by cocrystallization from mixtures of 1 and 2 or 2 and 3, respectively. It was shown that π-stacking interactions are involved in increasing the efficiency of energy transfer from the gadolinium complex to emitting [TpPyEu]2+ or [TpPyTb]2+ centers, and this energy transfer occurs through hundreds of molecules, resembling the process of energy harvesting in chloroplast stacks.