A limited number of substances exhibit triboluminescence, the emission of light from crystals due to mechanical fracture. Francis Bacon, in 1605, was the first to report triboluminescence in sucrose crystals. To date, the mechanism of mechanically induced emission is not well understood. One hypothesis suggests that solids must exhibit chiral packing in the crystal form to exhibit triboluminescence. In an effort to force chiral packing, and ultimately design compounds to display triboluminescence, boron avobenzone complexes incorporating the chiral ligand R-mandelate were synthesized. Both [B(AVB)(R-man)] and the double salt [B(AVB)2][B(R-man)2] (AVB = Avobenzone, R-man = R-Mandelate) were characterized by 1H NMR, photoluminescence, and X-ray crystallography. The X-ray structure of [B(AVB)(R-man)] confirmed packing in the chiral space group P 212121 with chirality at mandelate and boron. Both compounds exhibit strong solid-state photoluminescence with a red shift of the maximum emission wavelength for the double salt compared with the neutral complex. Studies are underway to determine if these complexes undergo mechanically induced emission.

Photoluminescent boron avobenzone complexes with R-mandelate

2019 Spring National Meeting

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