Convenient and mild syntheses of two europium(III) complexes, Na[Eu(dipic) 2 $3H 2 O]$4H 2 O (dipic ¼ dipicolinate anions) and Na[Eu(dipic) 2 $phen]$H 2 O (phen ¼ 1,10-phenanthroline), were reported. These two europium(III) complexes were confirmed by 1 H NMR, FT-IR, UV-Vis spectroscopy, and elemental and lifetime analysis. Interestingly, the lifetimes were 2.31 ms and 2.38 ms for Na[Eu(dipic) 2 $3H 2 O]$4H 2 O in the solid state and in ethanol solution, respectively, though high-frequency vibrations were present in the first coordination sphere. Furthermore, the lifetime for Na[Eu(dipic) 2 $phen]$H 2 O in ethanol solution is 3.23 ms, which is the longest lifetime reported to date. The Na[Eu(dipic) 2 $phen]$H 2 O complexes exhibited a quantum yield of 36.1% in ethanol solution, which was longer than that of Na [Eu(dipic) 2 $3H 2 O]$4H 2 O. The value of the stimulated emission cross-section (s p ) for Na[Eu(dipic) 2 $phen]$ H 2 O in ethanol was very close to the values of the Nd-glass laser for practical use, which showed that it had potential application as a high-powered liquid laser medium.
Shape-tunable hollow silica nanomaterials, including hollow silica nano-spheres and nano-tadpoles, were synthesized with a one-step soft-templating method. A possible particle growth mechanism was proposed. Films were built from these shape-tunable hollow silica nanomaterials with refractive indices as low as 1.045, which is, to the best of our knowledge, the third-lowest value ever reported so far. For the first time, the refractive indices of films were tuned by changing the morphology of building blocks. These films are intrinsically hydrophobic. Moreover, the process used to prepare these nanomaterials without the need for expensive equipment or any post-treatment is well suited for industrial production on large surfaces.
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