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

[Image: see text] Neutral, flexible ditopic phosphine (P–P) or phosphine oxide (O=P–P=O) donors, rigid anionic bis-chelating oxygen donors, and Re(2)(CO)(10) were used to assemble ten phosphine oxide (P=O)-donor-based neutral monocyclic M(2)LL′-, bicyclic M(4)L(2)L″-, and bicyclic M(4)LL′(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.