Thermostable Nano Luminophores Composed of Europium Ions and Organic Ligands

Title Thermostable Nano Luminophores Composed of Europium Ions and Organic Ligands Author(s) Onodera, Hiromitsu; Nakajima, Ayako; Nakanishi, Takayuki; Fushimi, Koji; Hasegawa, Yasuchika Citation e-Journal of Surface Science and Nanotechnology, 13, 219-222 https://doi.org/10.1380/ejssnt.2015.219 Issue Date 2015-05-16 Doc URL http://hdl.handle.net/2115/72413 Rights ©2015 The Surface Science Society of Japan Rights(URL) https://creativecommons.org/licenses/by/4.0/ Type article File Information Surf.Sci.Nanotech.13.219.pdf


A. Apparatus
Infrared spectra were recorded with a JASCO FTIR-350 spectrometer.1H NMR (400 MHz) spectra were recorded with a JEOL ECS-400 spectrometer.Chemical shifts are reported in ppm and are referenced to an internal tetramethylsilane standard for 1H NMR spectroscopy.Elemental analyses were performed with a Yanaco CNH MT-6 analyzer.Thermogravimetric analysis (TGA) was performed on a Seiko EXSTAR 6000 (TG-DTA 6300) analyzer.Size-distributions were measured with a BECK-MAN COULTER Delsa Nano HC.High-resolution images of luminophore were obtained with a JEOL 2010 FASTEM (200 kV) TEM.

C. Preparation of 4,4'-bis(diphenylphosphoryl)biphenyl [dpbp]
4,4'-bis(diphenylphosphoryl)-biphenyl was synthesized according to the published procedure [30].A solution of n-BuLi (9.3 mL, 1.6 M hexane, 15mmol), was added dropwise to a solution of 4,4'-dibromobiphenyl (1.9 g, 6.0 mmol) in dry THF (30 mL) at −80 • C. The addition was completed in ca.15 min during which time a yellow precipitate was formed.The mixture was allowed to stir for 3h at −10 • C, after which a PPh 2 Cl (2.7 mL, 15 mmol) was added dropwise at −80 • C. The mixture was gradually brought to room temperature, and stirred for 14 h.The product was extracted with ethyl acetate, the extracts washed with brine for three times and dried over anhydrous MgSO 4 .The solvent was evaporated, and resulting residue was washed with acetone and ethanol for several times.The obtained white solid and dichloromethane (ca.40 mL) were placed in a flask.The solution was cooled to 0 • C and then 30% H 2 O 2 aqueous solution (5 mL) was added to it.The reaction mixture was stirred for 2 h.The product was extracted with dichloromethane, the extracts washed with brine for three times and dried over anhydrous MgSO 4 .The solvent was evaporated to afford a white powder.Recrystallization from dichloromethane gave white crystals of the titled compound.Yield: 1.1 g (33%).IR(KBr): 1120 (st, P=O) cm −1 .1HNMR (400 MHz, CDCl 3 , 25

F. Optical Measurements
The emission spectra of the lanthanide coordination polymers were measured with a JASCO F-6300-H spectrometer and corrected for the response of the detector system.The emission lifetimes of the lanthanide coordination polymers (solid state) were measured by using the third harmonic (355 nm) of a Q-switched Nd:YAG laser [Spectra Physics, INDI-50, full width at half maximum (fwhm) = 5 ns, λ = 1064 nm] and a photomultiplier (Hamamatsu photonics, R5108, response time 1.1 ns).The Nd:YAG laser response was monitored with a digital oscilloscope(Sony Tektronix, TDS3052, 500 MHz) http://www.sssj.org/ejssnt(J-Stage: http://www.jstage.jst.go.jp/browse/ejssnt/) e-Journal of Surface Science and Nanotechnology synchronized to the single pulse excitation.The emission lifetimes were determined from the slope of logarithmic plots of the decay profiles.

A. Structural characterizations
TEM image of standard [Eu(DPP) x ] n is shown in Fig. 2a).We observed various size of [Eu(DPP) x ] n nanoparticles.The average particle size was estimated to be 30 nm with large size distribution.The particle size of [Eu(DPP) x ] n was not controlled under reaction temperature and time.We have also attempted to control the particle size of [Eu(hfa) 3 (dpbp) x ] using addition of monodentate TPPO ligand as a polymerization terminator.Size distribution of [Eu(hfa) 3 (dpbp) x (TPPO) 1−x ] n (x : molecular ratio of dpbp) using DLS measurement is shown in Fig. 2b).The size distribution is dependent of the molecular ratio of bidantate dpbp ligands in [Eu(hfa) 3 (dpbp) x (TPPO) 1−x ] n .We also observed mono size-distribution of the particles using DLS measurements.Particle size of [Eu(hfa) 3 (dpbp) 0.20 (TPPO) 0.80 ] n was found to be 115 nm.
These results indicate that particle size is controlled using monodentate TPPO ligands as a polymerization terminator.The thermal stabilities of size-controlled nanoparticles were characterized using thermogravimetric analyses (Fig. 3).

IV. CONCLUSIONS
The nanoparticles including Eu(III) ions were successfully prepared by addition of monodentate TPPO lig-ands as the polymerization terminator.The particle size is controlled using the molecular ratio of the bidentate dpbp ligands and the monodentate TPPO ligands.In this study, we successfully observed photo-sensitized luminescence of Eu(III) nanoparticles excted at 380 nm.However, their thermal stability and emission properties are dominated by monodentate TPPO ligands on the nanoparticles surface.In order to prepare thermo-stable luminescent Eu(III) nanoparticles, improvement of the polymerization terminator on the particle surface may be required.The size-controlled nanoparticles expected to open up the new application of future optical materials.