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Syntheses, Structure, and Photoluminescence Properties of the 1-Dimensional Chain Compounds [(TPA)2Au][Au(CN)2] and (TPA)AuCl (TPA = 1,3,5-Triaza-7-phosphaadamantane)
journal contribution
posted on 2002-10-31, 00:00 authored by Zerihun Assefa, Mohammad A. Omary, Brian G. McBurnett, Ahmed A. Mohamed, Howard H. Patterson, Richard J. Staples, John P. FacklerThe structures and temperature-dependent photoluminescence properties of the one-dimensional compounds
[(TPA)2Au][Au(CN)2], 1, and (TPA)AuCl, 2, are reported. An extended linear chain with weak Au···Au interactions
along the c-axis is evident in the structure of 1, and a helical chain with a pitch of 3.271 Å is seen for 2. The
intrachain Au···Au separation is 3.457(1) and 3.396(2) Å in 1 and 2, respectively. As a result of this weak Au···Au
interaction, the physical properties of these compounds are anisotropic. Scanning electron microscopy (SEM) studies
indicate that single crystals of both compounds are noninsulating. Single crystals of 1 do not luminesce visibly, but
grinding the crystals finely initiates a strong green emission under UV irradiation at room temperature. Further
interesting optical properties include the dependence of the emission profile of the powder on the exciting wavelength
and luminescence thermochromism. When excited at wavelengths < 360 nm, the powder exhibits a blue emission
at 425 nm while excitation with longer wavelengths leads to a green emission near 500 nm. While the green
emission dominates at ambient temperature, cooling to cryogenic temperatures leads to the dominance of the blue
emission. Fibers of 2 are luminescent at 78 K with an emission band centered at 580 nm. Compound 1 crystallizes
in the orthorhombic space group Cccm (No. 66), with Z = 2, a = 6.011(1) Å, b = 23.877(6) Å, c = 6.914(1) Å,
V = 992.3(3) Å3, and R = 0.0337. Compound 2 crystallizes in the trigonal space group R3̄ (No. 148), with Z =
18, a = 22.587(2) Å, b = 22.587(2) Å, c = 9.814(2) Å, V = 4336 Å3, and R = 0.0283.
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425 nmemission profile3.271 ÅTPAcryogenic temperaturescompound580 nmhelical chainspace group Cccm4336 Å 3ambient temperatureScanning electron microscopyluminescence thermochromism500 nmSEMPhotoluminescence Properties2 crystallizesemission bandSingle crystalspowder exhibits78 Kwavelength360 nmroom temperatureUV irradiationCompound 1 crystallizes
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