The diimine-dithiolato complexes Pt(dmecb)tdt and Pt(bpym)tdt (dmecb = 4,4′-dimethoxyester-2,2′-bipyridine; tdt2− = 3,4-toluenedithiolate; bpym = 2,2’-bipyramidine) were prepared and combined with strong nitrofluorenone electron acceptors 2,7-dinitro-9-fluorenone (DNF), 2,4,7-trinitro-9-fluorenone (TRNF), and 2,4,5,7-dinitro-9-fluorenone (TENF) to form supramolecular donor-acceptor charge transfer stacks. The results act to generalize this behavior we have reported recently for other representative complexes (JACS, DOI: 10.1021/ja506583k). The solid adducts have continuous absorptions throughout the visible spectrum including longer wavelengths that are not absorbed by neither the donor nor the acceptor alone. These donor-acceptor interactions are shown to persist in solution as low energy absorption bands. Solid state diffuse reflectance spectra have significant red-shifted absorption cutoffs and increased intensities compared to the solution indicative of a narrowing band gap to a semiconducting state in the solid. Such behavior suggests integrated stacks of donor and acceptor molecules and is supported with crystallographic data. Peak broadening found in 1H-NMR studies suggest paramagnetism in the adduct as a result of partial reduction of the acceptor and upfield shifts compared to free components from increased shielding are observed. 2D nuclear Overhauser spectroscopy (NOESY) spectra allude to coupling between protons in the donor-acceptor complex.

Generalization of the donor-acceptor charge transfer complexation of Pt(bipyridine)(dithiolate) donors and nitrofluorenone acceptors to exhibit “black-absorber” behavior in the solid state and solution

249th National Meeting (2015)

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