Molecules 2019, 24, 685
7 of 9
3+
3
.3. Preparation of the Ln -Exchanged ZY
ZY (1 g) was dispersed in an ethanol solution of LnCl (0.1M) (Ln = Eu or Tb), and then the
3
◦
mixture was stirred at 60 C for 24 h. The product was recovered by centrifugation, washed with
deionized water for three times and dried at 70 C, which was donated as Ln @ZY.
◦
3+
3+
3
.4. Preparation of the Luminescent Hybrid Composite Ln (HPBAn)@ZY
3+
Ln @ZY (200 mg) and HPBA (100 mg) were manually ground for 30 min, and the product was
◦
washed with dichloromethane three times following by drying at 70 C for 12 h.
−
12
3
.5. Exposure to Aqueous Ammonia (Concentration from 10
to 0.25 wt%)
3+
The powder samples of Ln (HPBA
n
)@ZY were used to detect ammonia concentration. For each
experiment, the composite (200 mg) was put in a small bottle and exposed to aqueous ammonia.
The powder samples and the small bottle were placed into a sealed container (about 100 mL), which
contained about 5 mL liquid for 1 h.
4
. Conclusions
In summary, we have prepared novel luminescent composites by doping lanthanide complexes to
the cavities of ZY through the so-called “ship-in-a-bottle” method. Samples of both Tb(HPBA )@ZY
and Eu0.5Tb0.5(HPBA ) @ZY show green emission under UV-light illumination, while no obvious
emission can be observed for Eu(HPBA )@ZY. The presence of ammonia vapors can make
Eu0.5Tb0.5(HPBA )@ZY and Eu(HPBA )@ZY emit red emission while severely quenching the
luminescence of Tb(HPBA )@ZY. This is because the ammonia can alter the energy level of the
ligand through deprotonation. In addition, Eu0.5Tb0.5(HPBA )@ZY exhibits high sensitivity to
low-concentrations of ammonia in aqueous solution, with exponential relationships between the
n
n
n
n
n
n
n
−
12
emission intensity ratio IEu/Tb and the concentration of ammonia in the range of 10 –0.5 wt%,
showing advantages like simple preparation, fast response and high sensitivity.
Supplementary Materials: The following are available online.
Eu0.5Tb0.5(HPBA )@ZY; Figure S2: Excitation (green solid line) and emission spectra (green dot line) of
Tb(HPBA )@ZY before treatment with NH vapor; excitation (black solid line) and emission spectra (black
dot line) of Tb(HPBA
blue dot line) of Eu(HPBA
spectra (red dot line) of Eu(HPBA
931 coordinates of Eu0.5Tb0.5(HPBA
Figure S1: The EDX spectrum of
n
n
3
n
)@ZY after treatment with NH vapor (a). Excitation (blue solid line) and emission spectra
3
(
n
3
)@ZY before treatment with NH vapor; excitation (red solid line) and emission
n
)@ZY after treatment with NH vapor (b); Figure S3: The corresponding CIE
3
1
n
)@ZY after treatment with different concentration of ammonium hydroxide;
)@ZY upon contact with amines for 10 min under near UV
Figure S4: Digital photographs of Eu0.5Tb0.5(HPBA
irradiation at 365 nm; Figure S5: FTIR spectrum of HPBA.
n
Author Contributions: H.L. supervised and coordinated all aspects of the project. Y.W. also coordinated this
work. Y.D. carried out synthesis and characterization, interpreted the data, and wrote the paper. P.L. and T.W.
commented the manuscript. All authors discussed and commented on the manuscript.
Funding: Financial support by the National Natural Science Foundation of China (21171046, 21502039, 21271060),
the Natural Science Foundation of Hebei Province (No. B2016202147, B2016202149, B2017202048), Educational
Committee of Hebei Province (LJRC021, QN2015172). Hebei Provincial College of Science and Technology
Research Project (BJ2018054). Tianjin Natural Science Foundation (18JCYBJC17200).
Conflicts of Interest: The authors declare no conflict of interest
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