Luminescence ligand field effect

Yb(5d)(H20)3]Cl, and [Yb(5d)(CoP] (fig. 12) where CoP is the cyclopentadienyl-tris(dieth-ylphosphito)cobaltate(I) anion (see fig. 13) for which the luminescence intensity increases in the proportions 1 22 36 62 271, upon excitation at 512 nm (Meng et al., 2000). The effect of coordinated water molecules on the metal-centered fluorescence intensity is clearly seen in the more than four-fold enhancement obtained by replacing the three water molecules in [Yb(5d)(H20)3 ]C1 by CoP the 2F5/2 lifetime of the latter complex (40 ps) is also much longer than lifetimes reported for other Ybm porphyrinates. In addition, the cobaltate anion rigidities the molecule, which results in a much finer structure of the ligand-field split electronic levels. 

The trans-Rh(cydam)(CN)2 ion (cyclam = 1,4,8,11-tetraazacyclotetradecane) displays luminescence from a ligand field excited state ( LF ) in room temperature, aqueous solution with a lifetime (8.1 ps) [83], several orders of magnitude longer than generally observed for rhodium(III) amines [37]. This emission is quenched by OH in solution (Eq. 6.38), a process attributed to amine deprotonation [84] at rates approaching the diffusion limit (kq 10 M" s ). The pressure effects on... 

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