Luminescent Coordination Glass: Remarkable Morphological Strategy for Assembled Eu(III) Complexes

Syntheses of novel luminescent Eu­(III)
coordination glasses 1 ([Eu­(hfa)3(o-dpeb)]2), 2 ([Eu­(hfa)3(m-dpeb)]3), and 3 ([Eu­(hfa)3(p-dpeb)]n) are
reported. They are composed of Eu­(III) ions, hexafluoroacetylacetonato
(hfa) ligands, and unique bent-angled phosphine oxide (o-, m-, p-dpeb) ligands with ethynyl
groups. Their coordination structures and glass formability are dependent
on the regiochemistry of substitution in regard to the internal benzene
core. Single-crystal X-ray analyses and DFT calculation reveals dinuclear,
trinuclear, and polymer structures for Eu­(III) coordination glasses 1, 2, and 3, respectively. Those
compounds show characteristic glass-transition (Tg = 25–96 °C) and strong luminescence properties
(ΦLn = 72–94%).