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Controlling Near-Infrared Chromophore Electronic Properties through Metal-Ligand Orbital Alignment
Nicole M Mews1, Andreas Berkefeld1, Gerald Hörner2
1Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Abstract:
Transition-metal complexes of radical ligands can exhibit low-energy electronic transitions in the near-infrared (NIR) spectral region. NIR band energy and intensity sensitively depend on the degree of electronic coupling of the chromophore. Using the example of open-shell complexes derived from platinum and a 1,4-terphenyldithiophenol, we present a novel approach toward spectroscopically distinct NIR dyes for which the degree of electronic coupling correlates with the relative orientation of radical ligand and metal orbitals. Ligand/metal orbital alignment is modulated by auxiliary phosphine donors and selectively results in electron localized Class II-III or delocalized Class III structures that display distinct NIR transitions at 6500 and 4000 cm-1.
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