Bimetallic hard-soft metal centers supported by mesoporous silica have been shown to reduce carbon dioxide (CO<sub>2</sub>). This reaction is one of the first steps in artificial photosynthesis, a way to combat rising levels of carbon dioxide by creating energy-rich fuels from environmental carbon and sunlight. In synthesized samples, electron transfer (ET) occurs from the cobalt (II) center to the zirconium (IV) center. The excited metal centers are then able to react with the carbon dioxide. However, a parallel back-electron transfer (BET) process, wherein the electron relaxes back to its original energy level within the cobalt 3d orbitals, reduces the availability of excited electrons for further reaction. The energy levels of the cobalt orbitals can be adjusted by substituting different amine ligands (triethylamine, diethylamine, diisopropylethylamine, azetidine, and <i>N</i>-methylpiperidine) on the cobalt to make BET less energetically favorable. To judge the efficacy of the amine group in reducing BET, time-correlated single-photon counting fluorimetry measurements were used to measure the rate and amount of back-electron transfer.

Photophysics of cobalt-zirconium heterobimetallic materials with ancillary amine ligands

253rd National Meeting (2017)

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