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%).