Chelation of Metal Ions in a Double Hydroxide
Anal. Found/calcd (%). For [LiAl2(OH)6](CoC10H12N2O8)0.5
‚
3H2O (Li,AL-LDH-CoY): Al, 14.03/13.82; Li, 1.79/1.78; Co,
7.48/7.54; Cl, 0.89/0; C, 15.23/15.38; H, 4.61/4.65; N, 3.41/3.59.
For [LiAl2(OH)6](NiC10H12N2O8)0.5‚3H2O (Li,Al-LDH-NiY): Al,
14.85/13.82; Li, 1.68/1.78; Ni, 7.02/7.52; Cl, 0.49/0; C, 14.83/15.38;
H, 4.80/4.65; N, 3.30/3.59. For [LiAl2(OH)6](CuC10H12N2O8)0.5
‚
3H2O (Li,Al-LDH-CuY): Al, 14.26/13.74; Li, 1.75/1.77; Cu, 7.98/
8.09; Cl, 0.49/0; C, 15.29/15.29; H, 4.58/4.62; N, 3.38/3.57. For
Na2NiC10H12N2O8‚4H2O (Na2NiY): Na, 9.89/9.89; Ni, 12.61/12.62;
C, 28.93/25.83; H, 4.74/4.33; N, 6.59/6.03. For Na2CoC10H12-
N2O8‚2H2O (Na2CoY): Na, 11.53/10.71; Co, 13.94/13.73; C, 26.35/
27.99; H, 3.76/4.37; N, 5.97/6.53. For Na2CuC10H12N2O8‚3.5H2O
(Na2CuY): Na, 10.58/9.98; Cu, 13.84/13.79; C, 25.91/26.07; H,
4.33/4.16; N, 5.82/6.08.
Synthesis of Li,Al-LDH-HY/MA2. The intercalates Li,Al-
LDH-HY/MA2 were prepared by suspending 1 g of Li,Al-LDH-
HY in 40 mL of 4.2 × 10-2 M aqueous solutions of the MA2 salts
{M ) Co2+, Ni2+, and Cu2+; A ) Cl-, NO3-, and CH3COO-
(Ac-)}. The reaction mixtures were kept at room temperature for
1 h with constant stirring. The final products were isolated by
filtration, then washed with deionized water, and dried at ∼50 °C
in air.
Figure 1. IR spectra of the intercalates: (a) Li,Al-LDH-Cl; (b) Li,Al-
LDH-H2Y; (c) Li,Al-LDH-HY.
Anal. Found/calcd (%). For [Li0.66Al2(OH)6](CoC10H12N2O8)0.33
‚
by integrating the peak intensities using a Gaussian fitting routine.
All the synthetic conditions in EDXRDs were repeated as in the
laboratory, except the reaction vessel, which was replaced by a
glass tube to fit the experimental cell.
2H2O (Li,Al-LDH-HY/CoAc2): Al, 17.80/ 17.34; Li, 1.54/1.49;
Co, 6.21/6.25; C, 11.56/12.74; H, 4.58/4.52; N, 2.59/2.97. For
[Li0.66Al2(OH)6](NiC10H12N2O8)0.33‚2.5H2O (LDH-HY/Ni(Ac)2):
Al, 17.12/16.86; Li, 1.44/1.44; Ni, 6.18/6.05; C, 11.40/12.38; H,
4.08/4.71; N, 2.43/2.89. For [Li0.66Al2(OH)6](CuC10H12N2O8)0.33
‚
Results and Discussion
2H2O (Li,Al-LDH-HY/Cu(Ac)2): Al, 17.63/17.25; Li, 1.46/1.48;
Cu, 7.18/6.71; C, 11.95/12.67; H, 3.98/4.50; N, 2.62/2.96. For
[Li0.75Al2(OH)6](CoC10H12N2O8)0.25Cl0.25‚2.5H2O (LDH-HY/Co-
Cl2): Al, 18.00/17.87; Li, 1.72/1.72; Co, 4.34/4.88; Cl, 2.81/2.94;
C, 10.29/9.95; H, 4.26/4.67; N, 2.17/ 2.32. For [Li0.75Al2(OH)6]-
(NiC10H12N2O8)0.25Cl0.25‚3H2O (Li,Al-LDH-HY/NiCl2): Al, 17.28/
17.36; Li, 1.60/1.67; Ni, 4.05/4.72; Cl, 3.08/2.85; C, 9.79/9.66; H,
Synthesis of Li,Al-LDH-HnY Intercalates. The treat-
ment of Li,Al-LDH-Cl with solutions of Na2H2Y at pH )
4.5 and 8.0 leads to almost complete deintercalation of Cl-
and intercalation of H2Y2- and HY3-, respectively. Chemical
analysis of mother liquors showed that the aluminum content
did not exceed 2%, indicating that no significant dissolution
of the Li,Al-LDH host had taken place. Elemental analysis
of the solid products showed that their compositions cor-
respond closely to the formula [LiAl2(OH)6](H2Y)0.5‚2.5H2O
and [LiAl2(OH)6](HY)0.33‚2.5H2O, respectively. As seen from
their IR spectra (Figure 1), the materials exhibit bands which
are characteristic of the ligand: poorly resolved ν-CH
vibrations at 2900-3000 cm-1, ν-CN vibrations at ∼1100
cm-1, and strong asymmetrical and symmetrical ν-COO
vibrations at ∼1600 and ∼1400 cm-1, respectively. The IR
spectra also display bands attributable to the Li,Al-LDH
matrix: δ-AlOH (∼960 cm-1), ν-AlOH (∼750 cm-1), and
δ-AlO6 (∼530 cm-1) vibrations. Comparing the spectra of
Li,Al-LDH-H2Y and Li,Al-LDH-HY shows that the treat-
ment at higher pH causes a significant decrease in absorbance
of the band at 1615 cm-1 and increase in absorbance of the
band at 1580 cm-1. We believe this is due to the decrease
in the protonation of the intercalated ligand.
4.26/4.86; N, 2.04/2.25. For [Li0.75Al2(OH)6](CuC10H12N2O8)0.25
-
Cl0.25‚2.5H2O (Li,Al-LDH-HY/CuCl2): Al, 18.17/17.61; Li, 1.60/
1.72; Cu, 5.78/5.24; Cl, 2.81/2.92; C, 10.86/9.91; H, 4.17/4.66; N,
2.26/2.31. For [Li0.8Al2(OH)6](CoC10H12N2O8)0.25(NO3)0.2(H2C10H13-
N2O8)0.05‚2.5H2O (Li,Al-LDH-HY/Co(NO3)2): Al, 17.23/16.85;
Li, 1.97/1.73; Co, 4.06/4.60; C, 10.94/11.25; H, 4.38/4.63; N, 3.50/
3.50. For [Li0.8Al2(OH)6](NiC10H12N2O8)0.25(NO3)0.2(H2C10H13-
N2O8)0.05‚2.5H2O (Li,Al-LDH-HY/Ni(NO3)2): Al, 16.76/16.85; Li,
1.78/1.73; Ni, 5.01/4.58; C, 10.76/11.25; H, 4.32/4.63; N, 3.17/
3.50. For [Li0.8Al2(OH)6](CuC10H12N2O8)0.25(NO3)0.2(H2C10H13-
N2O8)0.05‚3H2O (Li,Al-LDH-HY/Cu(NO3)2): Al, 16.36/16.33; Li,
1.67/1.68; Cu, 5.59/4.81; C, 10.86/10.90; H, 4.19/4.79; N, 3.45/
3.39.
The chemicals used in the syntheses were purchased from either
Aldrich or Reachim, with purities above 98%.
Instrumentation. Powder X-ray diffraction (XRD) patterns were
recorded with a Philips PW1710 diffractometer using Cu KR
radiation with a scan speed 2° (2θ)/ min. IR spectra were recorded
with a Perkin-Elmer 1600 FTIR spectrometer using KBr pellets.
UV-vis diffuse reflectance spectra were recorded with a VSU-2P
spectrometer using MgCO3 as a standard.
Time-resolved in-situ energy-dispersive X-ray diffraction experi-
ments (EDXRDs) were performed on Station 16.4 of the U.K.
Synchrotron Radiation Source, Daresbury Laboratory, U.K., using
an experimental setup which has been described elsewhere.24
Individual spectra were collected with acquisition times of 30 s
and a fixed detector angle (2θ) of 1.80°, which provided a d spacing
range ∼ 5-20 Å. Analysis of the diffraction peaks was performed
The powder XRD patterns indicate that intercalation of
the EDTA ligand into Li,Al-LDH-Cl gives rise to a
significant increase of interlayer separation from 7.65 to 12.1
(24) Clark, S. M.; Nield, A.; Rathbone, T.; Flaherty, J.; Tang, C. C.; Evans,
J. S. O.; Francis, R. J.; O’Hare, D. Nucl. Instrum. Methods 1995, 97,
98. Clark, S. M.; Cernik, R. J.; Grant, A.; York, S.; Atkinson, P. A.;
Gallagher, A.; Stokes, D. G.; Gregory, S. R.; Harris, N.; Smith, W.;
Hancock, M.; Miller, M. C.; Ackroyd, K.; Farrow, R.; Francis, R. J.;
O’Hare, D. Mater. Sci. Forum 1996, 228, 213.
Inorganic Chemistry, Vol. 42, No. 6, 2003 1921