Dominique Armspach

Slightly different reaction conditions afforded two distinct cavity‐shaped cis ‐chelating diphosphanes from the same starting materials, namely diphenyl(2‐phosphanylphenyl)phosphane and an α–cyclodextrin‐derived dimesylate. Thanks to their metal‐confining properties, the two diphosphanes form only mononuclear [CuX(PP)] complexes (X=Cl, Br, or I) with the tricoordinated metal ion located just above the center of the cavity. The two series of Cu I complexes display markedly different luminescence properties that are both influenced by the electronic properties of the ligand and the unique steric environment provided by the cyclodextrin (CD) cavity. The excited state lifetimes of all complexes are significantly longer than those of the cavity‐free analogues suggesting peculiar electronic effects that affect radiative deactivation constants. The overall picture stemming from absorption and emission data suggests close‐lying charge‐transfer (MLCT, XLCT) and triplet ligand‐centered (LC) excited states.