Supramolecular trinuclear

Supramolecular Entities of Trinuclear Cold(l) Complexes Sandwiching Small Organic Acids... 

Rawashdeh-Omary, M.A., Pietroni, B.R. and Staples, R.J. (2000) Supramolecular chain assemblies formed by interaction of a B molecular acid complex of mercury with B-Base trinuclear gold complexes. Journal of the American Chemical Society, 122, 11264. 

Omary M.A., Mohamed, A.A., Rawashdeh-Omary, M.A. and Fackler, J.P. Jr (2005) Photophysics of supramolecular binary stacks consisting of electron-rich trinuclear Au(I) complexes and organic electrophiles. Coordination Chemistry Reviews, 249, 1372-1381. 

Vickery, J.C., Olmstead, M.M., Fung, E.Y. and Balch, A.L. (1997) Solvent-stimulated luminescence from the supramolecular aggregation of a trinuclear gold(I) complex that displays extensive intermolecular Au Au interactions. Angewandte Chemie, 109, 1227-1229 (1997) Angewandte Chemie (International Edition in English), 36, 1179-1181. 

In this section, I will comment on selected examples of luminescent supramolecular architectures built through Au-Au interactions, both in the solid state and/or, when there is enough evidence, in solution. This topic will be divided into four parts based on the unit that by repetition gives rise to the supramolecular network, that is mononuclear, binuclear, trinuclear and higher nuclearity systems. 

Cyclic trinuclear gold(I) complexes provide a novel and productive strategy for achieving supramolecular structures. While molecules of this type have been known for more than twenty years, some of their remarkable properties have only been recognized recently. Some can form liquid crystals at room temperature [41], while others lead to luminescent materials with surprising properties. We will now summarize some selected examples to illustrate the behavior of these trinuclear systems. 

The use of other potential bidentate ligands also permits the synthesis of cyclic trinuclear gold complexes that form, by stacking, supramolecular assemblies. This is the case for the trinuclear complex [Au3(NC5H4)3] [47] that crystallizes in two... 

The complex is luminescent in the solid state and in solution in pyridine. The absorption spectrum shows a maximum at 340 nm and the emission spectrum displays a band at 425 nm. The crystals are also luminescent, but the excitation and emission spectra appear at different wavelengths. Thus, the complex emits at 490 nm and the excitation spectrum is complicated, with bands in a wide range from 300 to 450 nm. This result suggests that different species are responsible for luminescence in the solid state and in solution, with the isolated trinuclear complex being the emitting species in solution, while the luminescent properties of the crystal are the result of the extended supramolecular aggregation in the solid. As before, the complex did not exhibit solvoluminescence. 

In the case of the trinuclear [ t-N1,C2-bzimAu]3 (bzim = benzylimidazolate), in addition to the extended structures that form with other metals (see Section 6.3), it also forms supramolecular networks, acting as an electron donor with small organic acids [48]. For example, it reacts with TCNQ (tetracyanoquinodimethane) giving rise to a columnar structure in which each TCNQ molecule is sandwiched between two units of the trinuclear complex in a face-to-face manner. Thus, the repetition of this pattern leads to a stacking of the type (Au3)(Au3)( t-TCNQ)(Au3)... 

The first descriptions of heteronuclear luminescent supramolecular complexes were given by Fackler et al. in 1988 and 1989. In these studies, one gold-thallium and one gold-lead complex were reported. As in the case of the gold-silver dinuclear systems, the extended systems appeared as a result of the unidirectional polymerization of dinuclear or trinuclear units through metal-metal interactions. These were prepared by reaction of the gold precursor [PPN][Au(MTP)2] (PPN = N(PPh3)2 ... 

We present here a few examples of enantiomeric supramolecular absolute structures. In fact, many supramolecular diastereomers with chiral ligands have been isolated stereoselectively. For example, enantiomers of the chiral self-assembled triple helicates trinuclear [Ni3(L)3](C104)6 (L = tris(bpy)) and dinuclear [Co2(L)3]4 + (L = 5-bismpmb) were partially resolved by SP Sephadex chromatography.63,64 The ligands and structures are given in Figure 5.17a and b. 

Figure 139. Formation of di- and trinuclear double-stranded helicates from a substituted sexipyridine ligand through supramolecular and electrochemical pathways.

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