Photoactive lanthanide complexes with phosphine oxides, phosphine oxide-sulfides, pyridine N-oxides, and phosphine oxide-pyridine N-oxides, and devices made with such complexes

A lanthanide compound comprising Formula XIV below:

• Ln(β-enolate)3(phosphine oxide-pyridine N-oxide)1 (XIV)
• where
• in Formula (XIV):
• phosphine oxide-pyridine N-oxide has Formula VII
• such that:
• in Formula VII:
• Y is the same or different at each occurrence and is selected from —CN, —OR1, —OH, —C(O)OR1, —Rf, aryl, X, —NO2, and —SO2R1,
• R1 is CsH2s+1,
• Rf is CsF2s+1,
• X is F, Cl, Br, or I,
• s is an integer from 1 to 6,
• β is 0 or an integer from 1 to 4,
• m is 0 or an integer from 1–12, and
• Q is the same or different at each occurrence and is selected from C6HnF5−n, and Cm(H+F)2m+1, where m is an integer from 1 to 12, and n is an 0 or an integer from 1 to 5.