Y. Zhang et al.
DyesandPigments157(2018)64–71
2. Experimental
400 M NMR spectrometer with the concentration of 5 mg/0.6 ml for
1HNMR and 30 mg/0.6 ml for 13CNMR in DMSO-d6.
2.1. Materials
Luminescence spectra of assembly solution. The luminescence
spectra of the luminescent solutions (0.01 M) were measured (The
choice of the concentration was based on Ref. [20]) at room tempera-
ture by the F-2500 fluorescence spectrophotometer from Hitachi, Japan
with the excitation wavelength 365 nm, the excitation slit width 5 nm
and the emission slit width 5 nm.
Luminescence spectra of white light emission solution at dif-
ferent temperature. The 0.02 M solution of Cn (n = 3,6) and the
0.02 M solution of Ln (NO3)3 (Ln = Eu, Tb) were prepared by using the
mixed solvent of DMF/CH3CN in 1:1 (v/v) ratio, and the white light
emitting solution (C3W) was prepared by mixing the 0.02 M solution of
C3 and the 0.02 M solutions of Ln (NO3)3 (Ln = Eu, Tb) in1:0.5:0.5 (v/
v) ratio. The room temperature solution was examined after 2 h in the
water bath at a constant temperature of 25 °C. The high temperature
solution was examined after 2 h in the water bath at a constant tem-
perature of 70 °C. The low temperature solution was examined after 2 h
in the refrigerator at a constant temperature of −20 °C. The setup of the
instrument here is similar to the one used for the measurements of lu-
minescence spectra of the solution.
Luminescence spectra of white light emission solution at dif-
ferent pH. The organic rare earth complex solutions with different pH
were prepared by mixing C3W (the preparation method is described as
above) with hydrochloric acid/aqueous sodium hydroxide solution
(10−n M, n = −1, 0, 1, 2, 3, 4, 5) in 9:1 (v/v) ratio. The setup of the
instrument here is similar to the one used for the measurements of lu-
minescence spectra of the solution.
Luminescence Decay. The luminescence decay of the luminescent
solution was tested by the Fluorolog3 steady state and transient state
fluorescence spectrometer from Horiba Jobin Yvon, Frence with the
excitation wavelength of 330 nm, the emission wavelength of 435 nm
and the attenuation interval from 0 to 200 ns, and the life-time values
were obtained.
Determination of gel properties. Heating and cooling method:
20 mg C3/C6 and 1 ml solvent were mixed in the test tube (φ = 10 mm)
sealed with tin foil. The test tube was heated with an alcohol burner
until the gelators were dissolved or could not be dissolved ever. Then
the solution was cooled to room temperature, staying overnight. If the
system obtains solid-liquid stratification, it is judged as precipitation
(P). If the compound is completely dissolved and transparent solution is
obtained, it is judged as dissolved (S). If the system has no liquid
flowing after inverting, it is judging as gel (G); If the system has little
liquid flowing after inverting, it is judging as weak gel (WG).
Critical gelator concentrations (CGCs). The concentration of gel
prepared by heating-cooling method was increased 0.1% by adding
solvent and repeated heating-cooling. The minimum concentration for
the gelator keeping gel performance judged by inversing the test tube is
the CGC.
Gluconolactone, pyridine-2-carboxylic acid ethyl ester, 6-amino-1-
hexanol, 3-aminopropanol and 4-dimethylaminopyridine were pur-
chased from Heowns Biochem Technologies. The chemical reagents
were commercially available and directly utilized without further
purification.
2.2. Synthesis
3-([2,2':6′,2″-terpyridin]-4′-yloxy)propan-1-amine (5a) and 6-
([2,2':6′,2″-terpyridin]-4′-yloxy)hexan-1-amine (5b). The key in-
termediates 5a and 5b were synthesized from the starting material 1.
The condensation reaction led to compound 2. The subsequent cycli-
zation (3) and two substitution reactions afforded 5. The detailed ex-
periment and characterization can be found in Ref. [29].
(2R,3S,4S,5S)-N-(3-([2,2':6′,2″-terpyridin]-4′-yloxy)propyl)-
2,3,4,5,6-pentahydroxyhexanamide (C3). The mixture of 5a (306 g/
mol, 7 mmol, 2.14 g), gluconolactone (178 g/mol, 7 mmol, 1.25 g) and
DMAP (4-dimethylaminopyridine, 122 g/mol, 0.08 mmol, 0.01 g) was
suspended in methanol (50 ml) at room temperature. After vigorous
stirring for 6 h, the solid was separated by filtration. Then the product
was obtained by washing with deionized water, methanol and CH2Cl2
respectively. Yield: 82%. 1HNMR (400 MHz, DMSO-d6): δ 8.72 (d,
J = 4.1 Hz, 2H), 8.61 (d, J = 7.9 Hz, 2H), 8.00 (td, J = 7.8, 1.5 Hz, 2H),
7.97 (s, 2H), 7.64 (t, J = 5.8 Hz, 1H), 7.50 (dd, J = 6.9, 5.3 Hz, 2H),
5.36 (d, J = 3.9 Hz, 1H), 4.53 (s, 1H), 4.47 (s, 1H), 4.41 (d, J = 7.0 Hz,
1H), 4.33 (s, 1H), 4.23 (t, J = 6.4 Hz, 2H), 3.99 (s, 1H), 3.91 (s, 1H),
3.58 (d, J = 7.8 Hz, 1H), 3.48 (s, 2H), 3.41–3.35 (m, 1H), 3.12 (tq,
J = 12.6, 6.3 Hz, 2H), 1.79 (dd, J = 13.9, 6.8 Hz, 2H). 13CNMR
(101 MHz, DMSO-d6): δ 173.14 (s), 167.19 (s), 157.08 (s), 155.37 (s),
149.70 (s), 137.80 (s), 124.92 (s), 121.36 (s), 107.30 (s), 74.19 (s),
72.91 (s), 72.01 (s), 70.67 (s), 66.48 (s), 63.83 (s), 35.67 (s), 29.19 (s).
HRMS (ESI-Q-TOF): m/z calc. for C24H29N4O7 (M+H)+: 485.2036,
found: 485.2031.
(2R,3S,4S,5S)-N-(6-([2,2':6′,2″-terpyridin]-4′-yloxy)hexyl)-
2,3,4,5,6-pentahydroxyhexanamide (C6). The mixture of 5b (348 g/
mol, 3.5 mmol, 1.22 g), gluconolactone (178 g/mol, 7 mmol, 1.25 g)
and DMAP (4-dimethylaminopyridine, 122 g/mol, 0.08 mmol, 0.01 g)
was suspended in methanol (50 ml) at room temperature. After vig-
orous stirring for 6 h, the solid was separated by filtration. Then the
product was obtained by washing with deionized water, methanol and
CH2Cl2 respectively. Yield: 78%. 1HNMR (500 MHz, DMSO-d6): δ 8.70
(dd, J = 2.7, 1.9 Hz, 2H), 8.60 (d, J = 7.9 Hz, 2H), 7.99 (td, J = 7.8,
1.7 Hz, 2H), 7.94 (s, 2H), 7.64 (t, J = 5.8 Hz, 1H), 7.48 (ddd, J = 7.4,
4.8, 1.0 Hz, 2H), 5.37 (d, J = 5.0 Hz, 1H), 4.55 (d, J = 4.8 Hz, 1H), 4.48
(d, J = 5.2 Hz, 1H), 4.42 (d, J = 7.2 Hz, 1H), 4.34 (t, J = 5.7 Hz, 1H),
4.21 (t, J = 6.4 Hz, 2H), 4.01–3.94 (m, 1H), 3.90 (dd, J = 5.1, 1.9 Hz,
1H), 3.60–3.51 (m, 1H), 3.46 (d, J = 2.4 Hz, 2H), 3.15–3.04 (m, 2H),
1.85–1.70 (m, 2H), 1.50–1.40 (m, 4H), 1.37–1.29 (m, 2H). 13CNMR
(101 MHz, DMSO): δ 172.75 (s), 167.17 (s), 157.09 (s), 155.36 (s),
149.67 (s), 137.75 (s), 124.89 (s), 121.32 (s), 107.18 (s), 74.15 (s),
72.92 (s), 71.98 (s), 70.64 (s), 68.41 (s), 63.87 (s), 38.67 (s), 29.55 (s),
28.86 (s), 26.56 (s), 25.59 (s). HRMS (ESI-Q-TOF): m/z calc. for
Scanning electron microscopy of xerogel morphology. The xer-
ogel samples obtained by spontaneous evaporation in the air were
characterized by scanning electron microscope (SEM, Hitachi s-4800).
The accelerating voltage was 5 kV, and the emission current was 10 mA.
Infrared spectroscopy analysis. The xerogel samples of gelator
and gelator precipitate were prepared by KBr compression method at
room temperature. The samples were tested with Bruker ruker Equinox
C
27H35N4O7 (M+H)+: 527.2505, found: 527.2505.
55 infrared spectrometer with scanning wavelength of 500–3900 cm−1
.
X-ray diffraction. The samples were tested at room temperature
using a Bruker D8 Focus X-ray powder diffractometer. The data ac-
quisition conditions are as follows: copper target as radiation source
(λ = 1.5418 Å); scanning speed, 4。min−1; 2θ = 3–50°; step size 0.02°.
Calculation method. Using the Gaussian 09 software and method
of hybrid density functional theory (DFT) [27], the C6 and C3 mole-
cules were optimized and the lowest energy was calculated. ωB97xD
function in the DFT-D method is used to calculate the long-range in-
teraction of the molecule. In order to balance the calculation accuracy
2.3. Measurements
Mass spectrometry. High resolution mass spectra (HRMS) of C3,
C6 and their synthetic intermediates were recorded on the ESI-Q-Tof
(Bruker Daltonics-microTOF-QII). Mass spectra of C3-Eu and C6-Eu
complexes were recorded on the Maldi-Tof (Bruker Daltonics-Autoflex
TofIII).
NMR measurements. The study was carried out on a Bruker AV
65