Synthesis, Structural, and Photophysical Studies of Phenylquinoline and Phenylquinolinyl Alkynyl Based Pt(II) Complexes

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• 作者：Elena Lalinde ; M. Teresa Moreno ; Santiago Ruiz ; Sergio S谩nchez
• 刊名：Organometallics
• 出版年：2014
• 出版时间：June 23, 2014
• 年：2014
• 卷：33
• 期：12
• 页码：3078-3090
• 全文大小：585K
• ISSN：1520-6041

文摘

We present the synthesis, characterization, and photophysical properties of two series of alkynyl鈥損latinum(II) complexes containing the phenylquinoline (Hpq) or the cyclometalated phenylquinolinyl (pq) ligand. Unusual monoanionic complexes (NBu₄)[Pt(C鈮R)₃(Hpq)] (R = Tol 1, C₆H₄OMe-3 2, C₆H₄CF₃-4 3) were generated in moderate yield by treatment of [Pt(pq)(渭-Cl)]₂ with an excess of LiC鈮R (1:8), followed by subsequent treatment with NBu₄ in iPrOH. However, a similar reaction with LiC鈮^tBu evolves with formation of [Pt(pq)(渭鈥?i>魏C^伪:畏²-C鈮^tBu)]₂ 4. Related dimers [Pt(pq)(渭鈥?i>魏C^伪:畏²-C鈮R)]₂ (R = Tol 5, C₆H₄OMe-3 6, C₆H₄CF₃-4 7) were successfully prepared by modification of the reaction conditions. Single-crystal studies were performed on 2, 4, and 5, revealing the presence of intramolecular (H路路路Pt and H路路路C鈮) and intermolecular O_methoxy路路路H_Hpq contacts in 2 and the formation of butterfly structures in 4 and 5. In the ^tBu derivative 4, a shorter intramolecular Pt路路路Pt separation was found [3.0936(3) 脜 in 4 vs 3.2109(3) 脜 in 5], which is related to the nature of 畏²-alkynyl linkages (畏²-asymmetrical in 4 vs 畏²-symmetrical in 5). Anionic 1鈥?b>3 display bright emissions in rigid media (solid, glass) with resolved side vibronic bands at 77 K. The energy of the emissions (supported by computational studies on 2) allows us to ascribe these emissions primarily to a mixed alkynyl鈥搈etal to the phenylquinoline ³[(L鈥?+ M)LCT] excited state, being perturbed in 2 (solid) by the intermolecular O_methoxy路路路H_Hpq contacts. Whereas diplatinum complexes 5鈥?b>7 have no visible emission at 298 K in the solid state, 4 shows a structureless band (578 nm), which is significantly red-shifted at 77 K (595 nm). Theoretical studies suggest a notable distortion in the excited state in relation to S₀ and identify the emission within the dimetallacycle Pt₂(C鈮)₂ with alkynyl to pq charge-transfer ³[(MM + L鈥?LCT] [with minor ³IL (pq) contribution], whereas, in 5, the emission is tentatively ascribed to a mixture of ³L鈥睱CT with minor ³MMLCT character. The emission profiles observed in glassy solution for all 4鈥?b>7 complexes (556鈥?62 nm, CH₂Cl₂) and in the solid state for 6鈥?b>7 are consistent with those exhibited by mononuclear related chromophores ³[(L鈥?+ M)LCT] (L鈥?= C鈮R, L = pq), suggesting negligible contribution of the Pt路路路Pt interaction.