GeneralEuropium acetate n-hydrate (99.9%), terbium acetate tetrahydrate (99.9%), gadolinium acetate tetrahydrate (99.9%), 1.55 M n-butyllithium (n-BuLi) in n-hexane, and hydrogen peroxide were purchased from Kanto Chemical Co., Inc. 2,5-Dibromofuran, 3,4-ethylenedioxythiophene, 2,5-dibromothiophene, and chlorodiphenylphosphine (PPh 2 Cl) were obtained from Tokyo Chemical Industry Co., Ltd. All other chemicals and solvents were reagent grade and were used without further purification.

Thermosensitivity of emission intensity in a polymer comprised Tb3+ and Eu3+ can be controlled by the energy level of the organic linker-centered triplet state as well as that of the ligand-centered triplet state.

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%).

Novel Eu III coordination polymers [Eu(hfa)3(dpt)]n (dpt: 2,5-bis(diphenylphosphoryl)thiophene) and [Eu(hfa)3(dpedot)]n (dpedot: 2,5-bis(diphenylphosphoryl)ethylenedioxythiophene) with hydrogenbonded zipper structures are reported. The coordination polymers are composed of Eu III ions, hexafluoroacetylacetonato ligands, and thiophene-based phosphine oxide bridges. The zig-zag orientation of single polymer chains induced the formation of densely packed coordination structures with multiple intermolecular interactions, resulting in thermal stability above 300˚C. They exhibit a high intrinsic emission quantum yield (~ 80%) due to their asymmetrical and low-vibrational coordination structures around Eu III ions. In addition, the characteristic alternative orientation of substituents also contributes to the dramatically high ligand-to-metal energy transfer efficiencies of up to 80% in solid state.The development of luminescent molecular materials with high quantum efficiencies is required for applications in bioassays, light-emitting devices, and chemical and physical sensors. [1] There have been many reports on luminescent organic and coordination compounds. Swager and co-workers developed amplifying fluorescent conjugated polymers for biological and chemical sensors such as highly explosive trinitrotoluene in seawater. [2] Adachi et al. demonstrated very high phosphorescence efficiency of Ir III coordination compounds in organic light-emitting devices. [3] Among these materials, lanthanide coordination compounds are promising candidates for pure and strong luminophores due to their versatile photophysical properties derived from the 4f-4f transitions in lanthanide (Ln III ) ions. [4] Ln III ions, however, show small absorption coefficients (ε < 10 M -1 cm -1 ), and various organic chromophores such as β-diketonates and pyridinebased ligands have been developed to sensitize the luminescence of Ln III ions. [5] These organic compounds with π conjugation systems are referred to as light-harvesting antenna ligands. The overall emission quantum yields of Ln III compounds are described as ・・・ (1) where Φff is Ln III -centered emission quantum yield, ηsens is efficiency of the sensitization process, and kr and knr are radiative and nonradiative rate constants, respectively.Ln III coordination compounds with high Φff have been successfully synthesized by introducing asymmetric coordination structures, resulting in a large kr value. [6] In order to improve thermal and photophysical properties of Ln III compounds for optical applications, Ln III coordination polymers with rigid multidimensional networks have been developed over the past two decades. [7] The rigid coordination structures can also contribute to strong emission by suppressing a non-emissive process (knr) associated with vibrational relaxation.The antenna and bridging ligands in Ln III coordination polymers dominate their photophysical and thermodynamic properties. Bünzli and co-workers reported that Eu III coordination polymers with low-vibration...