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A series of new rhenium(I) complexes of the type [Ren + (L = 2,2'-biquinoline (bqui) or 3,3'-(ethane-1,2-diyl)-2,2'-biquinoline (CH 2 CN 2 )bqui); L' = CF 3 SO À 3 , pyridine (py), or 4-substituted pyridine (HOpy, Bzpy, or NCpy); n = 0 or 1) were prepared and characterized by FT-IR, 1 H-NMR, UV/VIS and emission spectroscopy, luminescence lifetimes, and cyclic voltammetry. The pseudo-octahedral facial configuration was established by X-ray single-crystal diffraction analysis of two complexes and by a FT-IR study of all complexes. The [Re(CO) 3 (bqui)(Bzpy)](CF 3 SO 3 ) complex crystallizes in the form of two mirror isomers arising from the conformational mobility of the biquinoline ligand. A correlation between the metal-to-ligand charge-transfer (MLCT) emission maxima and the s + Hammett parameter was established for the complexes of the bqui series, while such correlation was not observed for the complexes of the (CH 2 CH 2 )bqui series. No correlation between oxidation potentials and the Hammett parameters was established. The results were rationalized in function of the effect of the 4-substituted pyridine ligand on the octahedral distortion and conformational characteristic of the complexes. The 1 H-NMR data confirmed these results.