Precise Internal Postsynthetic Oxygen-Doping of Metallonanographenes

Heteroatom doping has the potential to alter the electronic structure and optical properties of nanographenes, thereby expanding the scope of their utility in various applications. In this work we demonstrate a strategy to introduce an oxygen atom directly and precisely into backbone of the already formed metal-nanographene complexes. Treating metal-nanographene complexes HBCP-M (M = Cu, Ag, Au) with Davis' oxaziridine produces oxygen-doped complexes HBCP-OM (M = Cu, Ag, Au) with adj-CONN coordination in one step. Compared with original metal complexes, the electronic structure, photophysical properties and molecular conformations of HBCP-OM show sharp changes, as indicated by steady and fs-transient absorption (TA) spectroscopies, DFT calculations and crystal structure analysis. Moreover, the reduction of coordination cavity of HBCP-OM due to oxygen insertion affects the metal-ligand interaction. This leads that HBCP-OCu, possessing a relatively small Cu-(III) cation, exhibits an extended near-infrared (NIR) absorption beyond 1300 nm that is not observed in HBCP-OAg and HBCP-OAu.