Luminescence chemosensors are a powerful tool for providing selective and sensitive detection of a variety of chemical stimulus. Hemilabile coordination complexes have recently been used as a new type of sensor that exhibits reversible binding in the presence of small molecule analytes. It has also been demonstrated that phosphine-ether hemilabile ligands coordinated to ruthenium (II) bipyridyl systems produce luminescent signals dependent upon analyte-coordination. The inner-sphere coordination detection mechanism of the complex produces a multitude of ligand field states which in turn allow for a tunable ligand field. In the presence of H₂O, phosphine-ether hemilabile ruthenium complexes have shown spectral shifts in the MLCT band of [Ru(bpy)₂POMe]⁺² of 8nm to the red when titrated against H₂O 5% (v/v). The results suggest many sensing applications for these hemilabile complexes, for example as humidity and carbon monoxide sensors. This talk is to focus on the synthesis, structure, and photophysics of hemilabile complexes. An exploration into the structure and chemistry of hemilabile coordination complexes provides insight for potential applications of this novel sensor technology.