Synthesis, Photophysics, and Reverse Saturable Absorption of Bipyridyl Platinum(II) Bis(acetylide) Complexes Bearing Aromatic Electron-Withdrawing Substituents on the Acetylide Ligands

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• 作者：Xu-Guang Liu ; Wenfang Sun
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：November 13, 2014
• 年：2014
• 卷：118
• 期：45
• 页码：10318-10325
• 全文大小：506K
• ISSN：1520-5215

文摘

Three platinum(II) bipyridyl bis((7-R-fluoren-2-yl)acetylide) complexes (R = benzoyl (Pt-1), 2-(N-phenylbenzimidazoly) (Pt-2), or 2-(3-phenylquinoxalinyl) (Pt-3)) are synthesized and characterized. Their photophysical properties and reverse saturable absorption are systematically investigated via UV鈥搗is absorption, emission, transient absorption, and nonlinear transmission spectroscopy/technique. All three complexes possess ligand-centered ¹蟺,蟺* transitions below 400 nm, and a broad, featureless ¹MLCT/¹LLCT absorption band in the region of 400鈥?50 nm in CH₂Cl₂ solutions. They are emissive in a variety of fluid solutions at room temperature and at 77 K glassy matrix. On the basis of the emission lifetime, solvatochromic effect, and thermally induced Stokes shift, the emitting states are tentatively ascribed to ³蟺,蟺*/³MLCT/³LLCT states for Pt-1, and predominantly ³MLCT/³LLCT states for Pt-2 and Pt-3 in polar solvents like CH₃CN. Pt-1鈥?b>Pt-3 also exhibit broad triplet excited-state absorption, i.e., 425鈥?00 nm for Pt-1 and Pt-3, and 425鈥?25 nm for Pt-2, from the same excited states that emit. Strong reverse saturable absorption (RSA) occurs at 532 nm for ns laser pulses from all of the complexes due to the stronger triplet excited-state absorption at this wavelength, suggesting that the 蟺-conjugated aromatic electron-withdrawing substituents at the fluorenylacetylide ligands enhance the RSA of the Pt(II) diimine bis(acetylide) complexes.