文摘
A new neutral cyclometalated platinum(II) solvate complex [cis-Pt(bzq)(C6F5)(acetone)] (1) has been prepared by easy C鈥揌 activation of 7,8-benzo[h]quinoline on the coordination sphere of [cis-Pt(C6F5)2(thf)2] (thf = tetrahydrofuran). The study of the reaction pathway has led us to the preparation of the bis(Hbzq) product [cis-Pt(C6F5)2(Hbzq)2] (2) and the benzoquinoline鈥揵enzoquinolate derivative [Pt(bzq)(C6F5)(Hbzq)] (3). This latter complex has been characterized by X-ray diffraction, showing the occurrence of 蟺路路路蟺 intermolecular stacking interactions associated to the deprotonated bzq units. The acetone molecule in [cis-Pt(bzq)(C6F5)(acetone)] can be easily displaced by alkynes, allowing the synthesis of the first reported 畏2-alkyne-cycloplatinate complexes [Pt(bzq)(C6F5)(畏2-RC鈮R鈥?] (R = H, R鈥?= Ph 4, tBu 5, Fc 6; R = R鈥?= Ph 7), which have been fully characterized spectroscopically and by DFT studies. These alkyne complexes are only moderately stable in solution, and all attempts to obtain crystals suitable for X-ray diffraction were fruitless. Nevertheless, in the case of the ferrocenyl derivative, crystals of complex [Pt(魏N:畏2-bzq-C鈮Fc)(C6F5)(渭-魏C伪:畏2-C鈮Fc)Pt(bzq)(C6F5)] (8), containing an unusual alkynyl-functionalized benzoquinoline chelate ligand, were systematically obtained. All complexes (except those containing the ferrocenyl fragment) present emissive properties in solution and solid state (77 K), related, in general, with intraligand (bzq) excited states with some mixing 3MLCT character, as supported by theoretical calculations. In solid state at room temperature, aggregation induced emission (AIE) is observed likely generated by intermolecular 蟺路路路蟺 stacking, as supporting by DFT calculations on 32. Interestingly, both types of excited states (3IL/3MLCT and AIE) seem to be close in energy in complexes 1 and 3, which show a significant luminescent thermochromism (green 77 K to orange 298 K).
