TY - JOUR
T1 - Selective Covalent Modification of Layered Double Hydroxide Nanoparticles with Tripodal Ligands on Outer and Interlayer Surfaces
AU - Muramatsu, Keisuke
AU - Hayashi, Shiori
AU - Kuroda, Yoshiyuki
AU - Oka, Yuya
AU - Wada, Hiroaki
AU - Shimojima, Atsushi
AU - Kuroda, Kazuyuki
N1 - Funding Information:
The authors thank Mr. Masaki Ito (MCCL, Waseda University) for his assistance with the AFM measurements. This study was supported in part by the Grants in Aid for Scientific Research (No. 17K06803 and No. 19H00833) and a Grant in Aid from Mitsubishi Materials Corporation. K.M. is grateful to the JSPS Research Fellowships for Young Scientists from MEXT and the Leading Graduate Program in Science and Engineering at Waseda University.
Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/5/4
Y1 - 2020/5/4
N2 - Layered double hydroxides (LDHs) have occupied an important place in the fields of catalysts, electrocatalysts, and fillers, and their applicability can be greatly enhanced by interlayer organic modifications. In contrast to general organic modification based on noncovalent modification using ionic organic species, this study has clarified in situ interlayer covalent modification of LDH nanoparticles (LDHNPs) with the tripodal ligand tris(hydroxymethyl)aminomethane (Tris-NH2). Interlayer-modified CoAl LDHNPs were obtained by a one-pot hydrothermal treatment of an aqueous solution containing metal salts and Tris-NH2 at 180 °C for 24 h. Tris-NH2 was covalently bonded on the interlayer surface of LDHNPs. Interlayer-modified NiAl LDHNPs were also similarly synthesized. Some comparative experiments under different conditions indicate that the important parameters for interlayer modification are the number of bonding sites per a modifier, the electronegativity of a constituent divalent metal element, and the concentration of a modifier; this is because these parameters affect the hydrolytic stability of alkoxy-metal bonds between a modifier and a layer of LDHNPs. The synthesis of interlayer-modified MgAl LDHNPs was achieved by adjusting these parameters. This achievement will enable new potential applications because modification of only the outer surface has been achieved until now. Interlayer-modified LDHNPs possessing CO3 2- in the interlayer space were delaminated into monolayers under ultrasonication in water. The proposed method provides a rational approach for interlayer modification and facile delamination of LDHNPs.
AB - Layered double hydroxides (LDHs) have occupied an important place in the fields of catalysts, electrocatalysts, and fillers, and their applicability can be greatly enhanced by interlayer organic modifications. In contrast to general organic modification based on noncovalent modification using ionic organic species, this study has clarified in situ interlayer covalent modification of LDH nanoparticles (LDHNPs) with the tripodal ligand tris(hydroxymethyl)aminomethane (Tris-NH2). Interlayer-modified CoAl LDHNPs were obtained by a one-pot hydrothermal treatment of an aqueous solution containing metal salts and Tris-NH2 at 180 °C for 24 h. Tris-NH2 was covalently bonded on the interlayer surface of LDHNPs. Interlayer-modified NiAl LDHNPs were also similarly synthesized. Some comparative experiments under different conditions indicate that the important parameters for interlayer modification are the number of bonding sites per a modifier, the electronegativity of a constituent divalent metal element, and the concentration of a modifier; this is because these parameters affect the hydrolytic stability of alkoxy-metal bonds between a modifier and a layer of LDHNPs. The synthesis of interlayer-modified MgAl LDHNPs was achieved by adjusting these parameters. This achievement will enable new potential applications because modification of only the outer surface has been achieved until now. Interlayer-modified LDHNPs possessing CO3 2- in the interlayer space were delaminated into monolayers under ultrasonication in water. The proposed method provides a rational approach for interlayer modification and facile delamination of LDHNPs.
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U2 - 10.1021/acs.inorgchem.0c00192
DO - 10.1021/acs.inorgchem.0c00192
M3 - Article
C2 - 32186868
AN - SCOPUS:85082054943
VL - 59
SP - 6110
EP - 6119
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 9
ER -