Spectroscopic Structure鈥揚roperty Relationships of a Series of Polyaromatic Platinum Acetylides

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• 作者：Thomas M Cooper ; Douglas M. Krein ; Aaron R. Burke ; Daniel G. McLean ; Joy E. Haley ; Jonathan Slagle ; Jennifer Monahan ; Albert Fratini
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：January 12, 2012
• 年：2012
• 卷：116
• 期：1
• 页码：139-149
• 全文大小：1170K
• 年卷期：v.116,no.1(January 12, 2012)
• ISSN：1520-5215

文摘

To develop a structure鈥搒pectroscopic property relationship in platinum acetylides having poly(aromatic hydrocarbon) ligands, we synthesized a series of chromophores with systematic variation in the number of fused aromatic rings (nFAR) and ligand topology (polyacene (L), polyphenanthrene (Z), or compact(C)). We measured ground-state absorption, fluorescence, and phosphorescence spectra. We also performed nanosecond and femtosecond transient absorption experiments. To extend the range of compounds in the structure鈥損roperty relationship, we did DFT calculations on an expanded series of chromophores. Both the DFT results and experiments show that the S₁ and T₁ state energies are a function of both nFAR and the ligand topology. In the L chromophores, the S₁ and T₁ state energies decrease linearly with nFAR. In contrast, the S₁ and T₁ state energies of the Z chromophores oscillate around a fixed value with increasing nFAR. The C chromophores have behavior intermediate between the L and Z chromophores. A parallel series of calculations on the ligands shows the same behavior. The S₁鈥揝_n energy obtained from ultrafast time-resolved spectra has a linear variation in nFAR. The rate constant for nonradiative decay, k_nr, was calculated from the S₁ state lifetime and decreases with an increasing number of 蟺 electrons in the aromatic ring. The result is consistent with the spin鈥搊rbit coupling caused by the central platinum heavy atom decreasing with larger nFAR. The present work shows that the framework developed for the analysis of poly(aromatic hydrocarbon) properties is useful for the understanding of the corresponding platinum acetylide complexes.