B. Li, et al.
DyesandPigments172(2020)107862
J = 1.0 Hz,Ar), 7.64 (2H, dd, J1 = 7.8 Hz, J2 = 1.0 Hz, Ar), 3.99 (6H, s,
2 OCH3), 1.54 (6H, s, 2 CH3).
squares refinement (XL) [69,70]. All non-hydrogen atoms were refined
with anisotropic displacement parameters. The positions of the hy-
drogen atoms around the carbon atoms were included using a riding
model. Hydrogen atoms of coordination water molecules and lattice
water molecules were found in the difference Fourier map. Crystal data
and structural refinement parameters are given in Table S1 and selected
bond lengths and angles of the compound 1 are listed in Table S2. Since
the single crystal quality of the compounds 2, 3, 4 and 5 is poor and is
not suitable the requirements of X-ray single crystal diffraction test,
unfortunately, we have not obtained their precise single crystal struc-
ture as desired, however, by microanalysis (elemental analysis, IR,
PXRD) and research experience, it could still prove that they are iso-
morphic.
13C NMR (DMSO‑d6,125 MHz, δ/ppm): 166.27, 155.99, 142.14,
138.52, 137.51, 131.20, 130.27, 129.23, 127.04, 121.60, 120.60,
52.45, 47.32, 27.04. Elemental analyses: Found: C, 80.52; H, 5.64%;
molecular formula C31H26O4 requires C, 80.50; H, 5.67%.
4, 4-(9,9-dimethyl-9H-fluorene-2, 7-diyl) dibenzoic acid (H2DLDA),
white powdery solid, mass: 1.125 g, yield: 90%, m.p./oC: > 200. IR
data (KBr, ν/cm−1): 3413 (O–H stretching); 3057 (=CH- stretching);
2956, 2926, 2855 (C–H stretching); 1683 (C]O stretching); 1594,
1504, 1447 (ph skeleton vibration); 1386 (C–H bending); 1285 (C–O
stretching). 1H NMR (DMSO‑d6,500 MHz, δ/ppm): 12.91 (2H, s,
2 COOH), 8.05 (4H, d, J = 8.1 Hz, Ar), 8.00–7.98 (4H, m, Ar), 7.91(4H,
d, J = 8.1 Hz, Ar), 7.76 (2H, d, J = 7.9 Hz, Ar), 1.58 (6H, s, 2 CH3). 13
C
NMR (DMSO‑d6, 125 MHz, δ/ppm):167.12, 154.72, 144.52, 138.38,
138.15, 129.89, 129.41, 126.83, 126.20, 121.45, 120.98, 46.87, 26.70.
Elemental analyses: Found: C, 80.15; H, 5.07%; molecular formula
3. Results and discussion
C
29H22O4 requires C, 80.17; H, 5.10%.
3.1. Synthesis
Compound 1-5 are obtained under hydrothermal conditions by
heating mixture solution contained rare earth nitrate salt and H2DLDA
for 4 days. Furthermore, attempts to vary other synthetic parameters
such as pH value, molar ratio of the reactants and the identity of the
base are also unsuccessful, only producing some precipitates or mi-
crocrystalline products (2–5) that are unsuitable for single crystal X-ray
diffraction analysis owing to making rapid aggregates except for 1. In
order to obtain the expected the better crystalline conditions of the
compounds, we mainly regulate from several aspects that affect the
reaction. The first is the environment of the reaction. The experiments
prove that hydrothermal synthesis is the optimum reaction conditions.
Secondly, we separately compare the molar ratio of the reactants, the
solvent selection and the dosage, the pH value of the system, the re-
action temperature and the reaction time. During a mass of the ex-
periments, we found that the selected solvent and the reaction tem-
perature play vital roles in the reaction process, so we tried different
reagents as solvents, and finally came to the conclusion that the mixed
solvents composed of DMF, EtOH and H2O were the best reaction
system, and their volume ratios are also regulated. Besides, through
different temperature attempts, such as 80, 100, 120, 140, 160 °C and it
was found finally at 120 °C to obtain the crystalline of the target
compounds.
2.2.3. Preparation of the compounds
0.0222 g of Sm(NO3)3·6H2O (0.05 mmol) and 0.0221 g of H2DLDA
(0.05 mmol) were dissolved in a mixture solution containing 5 mL of
DMF, 2 mL of EtOH and 1 mL of H2O, then, dilute nitric acid was used
to adjust the pH of the solution to 6–7. After stirring at room tem-
perature for 2 h, the mixture solution was put into Teflon-lined stainless
steel autoclave and heated at 120 °C for 4 days, finally, cooled to room
temperature, light yellow transparent crystals were obtained by
washing with ethanol. The synthesis procedures of the compounds 2-5
are similar to that of compound 1, except that the rare earth nitrates
used are different. Detailed elemental analysis and infrared data are as
follows:
[Sm(DLDA)(DMF)(H2O)(COO)]n (1) Mass obtained: 20.10 mg.
Yield: 56% (based on Sm3+). IR data (KBr, cm−1): 3447, 3124, 2959,
2861, 1673, 1590, 1409, 1282, 823, 765. Elemental Analyses: Found: C,
55.08; H, 4.14; N, 1.92%; molecular formula C33H30NO8Sm requires C,
55.12; H, 4.18; N, 1.95%.
[Eu(DLDA)(DMF)(H2O)(COO)]n (2) Mass obtained: 16.92 mg. Yield:
47% (based on Eu3+). IR data (KBr, cm−1): 3447, 3074, 2959, 2863,
1681, 1599, 1409, 1285, 853, 778. Elemental Analyses: Found: C,
54.98; H, 4.15; N, 1.91%; molecular formula C33H30NO8Eu requires C,
55.01; H, 4,17; N,1.94%.
[Ce(DLDA)(DMF)(H2O)(COO)]n (3) Mass obtained: 15.22 mg. Yield:
43% (based on Ce3+). IR data (KBr, cm−1): 3455, 3127, 2963, 2859,
1680, 1599, 1408, 1286, 817, 765. Elemental Analyses: Found: C,
55.88; H, 4.19; N, 1.95%; molecular formula C33H30NO8Ce requires C,
55.92; H, 4.24; N,1.98%.
[Nd(DLDA)(DMF)(H2O)(COO)]n (4) Mass obtained: 13.88 mg.
Yield: 39% (based on Nd3+). IR data (KBr, cm−1): 3448, 3155, 2914,
2841, 1650, 1570, 1401, 1248, 834, 780. Elemental Analyses: Found: C,
55.58; H, 4.19; N, 1.94%; molecular formula C33H30NO8Nd requires
C,55.60; H, 4,21; N,1.97%.
[Gd(DLDA)(DMF)(H2O)(COO)]n (5) Mass obtained: 14.14 mg.
Yield: 39% (based on Gd3+). IR data (KBr, cm−1): 3455, 3132, 2958,
2863, 1672, 1599, 1404, 1286, 817, 765. Elemental Analyses: Found: C,
54.58; H, 4.11; N, 1.90%; molecular formula C33H30NO8Gd requires C,
54.60; H, 4.14; N,1.93%.
3.2. IR spectra
By infrared spectroscopy analysis, the broader absorption band at
3447 cm−1 of compound 1 shown the presence of water molecules. The
peak position at 1673 cm−1 and 1409 cm−1 can be attributed to the
asymmetric stretching vibration of the C]O bond (νasCOO−) and the
C]O symmetric stretching vibration (νsCOO−), and compared to main
position of the carboxyl peak at 1684 cm−1 of the ligand H2DLDA, a red
shift occurred, indicating that the metal atom coordinated with the li-
gand. Detailed infrared spectral data of compounds 1-5 are shown in
Table S4. The infrared spectra of all compounds are shown in Fig. S1.
3.3. PXRD analyses
2.3. X-ray crystal structure determination
The PXRD spectra of compounds 1-5 were obtained and compared
with that of the corresponding simulated from single crystal data. As
shown in Fig. S2. The measured peaks of compounds 1-5 are very
consistent with the simulated values, and there were no other peaks,
indicating compounds 1-5 are pure phase. In addition, the peak posi-
tions of compounds 1-5 are identical, indicating that they are iso-
morphic compounds. The different intensity may be due to the pre-
ferred orientation of the powder samples.
Suitable single crystal of the compound 1 was mounted on glass
fibers for X-ray measurement. Reflection data were collected at room
temperature on a Bruker AXS SMART APEX II CCD diffractometer with
graphite monochromatized Mo-Kα radiation (λ = 0.71073 Å). A semi-
empirical absorption correction was applied by the program SADABS
[68]. The program suite SHELXTL-97 was used for space-group de-
termination (XPREP), direct method structure solution (XS), and least-
3