Synthesis, Spectroscopic Properties, and Photoconductivity of Black Absorbers Consisting of Pt(Bipyridine)(Dithiolate) Charge Transfer Complexes in the Presence and Absence of Nitrofluorenone Acceptor

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• 作者：Charles Browning ; Joshua M. Hudson ; Eric W. Reinheimer ; Fang-Ling Kuo ; Roy N. McDougald ; Jr. ; Hassan Raba芒 ; Hongjun Pan ; John Bacsa ; Xiaoping Wang ; Kim R. Dunbar ; Nigel D. Shepherd ; Mohammad A. Omary
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：November 19, 2014
• 年：2014
• 卷：136
• 期：46
• 页码：16185-16200
• 全文大小：917K
• ISSN：1520-5126

文摘

The diimine鈥揹ithiolato ambipolar complexes Pt(dbbpy)(tdt) and Pt(dmecb)(bdt) (dbbpy = 4,4鈥?di-tert-butyl-2,2鈥?bipyridine; tdt^{2鈥?/sup> = 3,4-toluenedithiolate; dmecb = 4,4鈥?dimethoxyester-2,2鈥?bipyridine; bdt2鈥?/sup> = benzene-1,2-dithiolate) are prepared herein. Pt(dmecb)(bdt) exhibits photoconductivity that remains constant (photocurrent density of 1.6 mA/cm2 from a 20 nm thin film) across the entire visible region of the solar spectrum in a Schottky diode device structure. Pt(dbbpy)(tdt) acts as donor when combined with the strong nitrofluorenone acceptors 2,7-dinitro-9-fluorenone (DNF), 2,4,7-trinitro-9-fluorenone (TRNF), or 2,4,5,7-tetranitro-9-fluorenone (TENF). Supramolecular charge transfer stacks form and exhibit various donor鈥揳cceptor stacking patterns. The crystalline solids are 鈥渂lack absorbers鈥?that exhibit continuous absorptions spanning the entire visible region and significant ultraviolet and near-infrared wavelengths, the latter including long wavelengths that the donor or acceptor molecules alone do not absorb. Absorption spectra reveal the persistence of donor鈥揳cceptor interactions in solution, as characterized by low-energy donor/acceptor charge transfer (DACT) bands. Crystal structures show closely packed stacks with distances that underscore intermolecular DACT. 1H NMR provides further evidence of DACT, as manifested by upfield shifts of aromatic protons in the binary adducts versus their free components, whereas 2D nuclear Overhauser effect spectroscopy (NOESY) spectra suggest coupling between dithiolate donor protons with nitrofluorenone acceptor protons, in correlation with the solid-state stacking. The NMR spectra also show significant peak broadening, indicating some paramagnetism verified by magnetic susceptibility data. Solid-state absorption spectra reveal further red shifts and increased relative intensities of DACT bands for the solid adducts vs solution, suggesting cooperativity of the DACT phenomenon in the solid state, as further substantiated by 谓_C鈥揙 and 谓_N鈥揙 IR bands and solid-state tight-binding computational analysis.}