Rhenium(I)-Based Monocyclic and Bicyclic Phosphine Oxide-Coordinated Supramolecular Complexes

Neutral, flexible ditopic phosphine (P–P) or phosphine oxide (OP–PO) donors, rigid anionic bis-chelating oxygen donors, and Re2(CO)10 were used to assemble ten phosphine oxide (PO)-donor-based neutral monocyclic M2LL′-, bicyclic M4L2L″-, and bicyclic M4LL′2-type supramolecular coordination complexes (SCCs). A soft ditopic phosphine donor was transformed into a hard ditopic phosphine oxide donor, during the formation of the cyclic complexes 1–3, 5–6, and 9–10. Complexes 4, 7, and 8 were obtained using a hard PO donor ligand. These SCCs were characterized using elemental analysis, FTIR, NMR, and single-crystal X-ray diffraction analysis. The absorption properties of 1–8 were studied using absorption UV–vis spectroscopic methods, and the results were analyzed using theoretical calculations. The results revealed that the neutral PO donor significantly influenced the photophysical properties by enhancing the absorption coefficient in the visible region.