The spectroscopic signatures of a dihydroxybenzene (catechol)-unit linked via an amide bond to a pyridyl-unit act as a guide to understand the signaling mechanism of the luminescent pH and molybdate sensor [Re (bpy)(CO) 3 (H 2-L)]+. The reaction of 2 equiv of [Re (bpy)(CO) 3 (H 2-L)]+ with molybdate leads to the formation of the zwitterionic Mo (VI) complex [MoO2 {Re (CO) 3 (bpy)(L)} 2] shown, as confirmed by ESI mass spectrometry ...
