Tribochromism, luminescence

Lee, Y.-A. and Eisenberg, R. (2003) Luminescence tribochromism and bright emission in gold(I) thiouradlate complexes. Journal of the American Chemical Society, 125, 7778-7779. 

The same laboratory describes a group of complexes with a unique property among metal complexes, referred to as luminescence tribochromism [39], which is a substantial change in the emission of the solid upon application of pressure. This phenomenon contrasts with the more common triboluminescence, which refers to the transient emission seen upon sample grinding or crushing. In this case, the effect was observed in a set of complexes of formula [Au2( J.-TU)((j,-dppm)]Y and [Au2( i-MeTU)( i-dppm)]Y (TU = 2-thiouracyl MeTU = 6-methyl-2-thiouracyl Y = CF3COOT NCV, CKV, Au(CN)2 ). 

In addition to electrical properties, the optical properties see Luminescence Behavior Photochemistry of Organ-otransition Metal Compounds) of the metal metal bonded unit have also received increased attention. Luminescence tribochromism hght emission that occurs with mechanical grinding - has been displayed by a An An dimeric complex where the monomeric unit with a An An separation of 2.8797 A arranges in a helical structure with alternating longer Au Au distances as shown in Figure 3. ... 

Figure 3 Au-Au dimeric unit that crystallizes, producing a helical arrangement conducive to luminescence tribochromism . (Reprinted with permission from Ref. 3. 2003 American Chemical Society)...

Some materials combine different colour-changing effects, such as thermochrom-ism and fluorescence, thermochromism and piezochromism, photochromism and ther-mochromism or tribochromism and luminescence [49,89]. 

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