Recent Research Developments

Index of Recent Research News
February 16th, 2005
Molecular Rods of GaN Emit Blue Light

    Figure 1. Structure of H3[(H6Ga3N3)9]H3

    Oligomeric rods of six-membered GaN rings connected through axial Ga-N bonds and coated with a shell of alkyl or hydrido ligands (Figure 1) were synthesized in ammonia at 150C. The rods luminescece towards the blue end of the visible spectrum with longer rods emitting at longer wavelengths (Figure 2). Computational studies established that the sigma framework molecular orbitals were localized in part due to the large dipole moments in the Ga-N rods. In particular, the Ga-N HOMO involved bonding orbitals localized at the negative end of the GaN rod, while the low-lying virtual orbitals exhibited localization towards the positive end. Thus, low lying excited states may be thought of as involving dipole assisted intramolecular charge transfer. Details appeared in the latest issue of J. Am. Chem. Soc. (2005, 127, 1493 - 1503). This research involved a collaboration between Profs. Gladfelter and Cramer at the U of M and Dr. Udo Pernesz at Dow Corning. Graduate student (at the time) Bethany Kormos, and postdocs Jolin Jegier and Paul Ewbank and crystallographer Vic Young were responsible for this project.

    Figure 2. Action (left) and emission (right two) spectra of H3[(H6Ga3N3)n]H3 for n = 10 - 12.

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Next scheduled update: March 2nd, 2005.
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