The design of non-noble metal-containing heterogeneous catalysts for the activation of small molecules is of utmost importance for our society. While nature possesses very sophisticated machineries to perform such conversions, rationally designed catalytic materials are rare. Herein, we aim to raise the awareness of the overall common design and working principles of catalysts incorporating aspects of biology, chemistry, and material sciences.

Herein we report a dinickel azacryptand complex that enables fast, selective, and tight CO2 binding from air. Exploiting the affinity of the cavitand towards azides, CO2 release was observed. Despite the stability of the azido complex, UV irradiation under atmospheric conditions proved to be a suitable pathway for N3(-) replacement by CO2.

While bimetallic azacryptands are known to selectively coordinate CO, there is little knowledge on how different substitution patterns of the azacryptand cage structure influence CO coordination. Stopped-flow UV-vis spectroscopy, electrochemical analysis and DFT calculations were performed on a series of dinickel azacryptands and showed different rates of CO coordination to the complexes. We herein present data showing that the different flexibility of the azacryptands is directly responsible for the difference in the CO uptake capability of dinickel azacryptand complexes.

The advantages of this procedure were lack of damage to the bronchoscope, the need for two instead of three persons to perform the PDT, and the excellent view inside the trachea. We recommend the ILM as a standard device for ventilation during bronchoscope-guided PDT.