Delamination of Layered Double Hydroxides Containing Amino Acids

Various amino acids were intercalated into Mg−Al layered double hydroxides (LDHs) as interlayer anions. The goal of this approach was to create an interlayer environment that was attractive to formamide, because of hydrogen bonding, so that penetration of formamide would lead to delamination. Some of the amino acid intercalates were successfully delaminated in formamide, but others were not. The intercalates that could not be delaminated had a high amino acid content, exceeding 15−20% of the charge occupation rate. At that rate, closely packed amino acids were likely to be tightly connected to one another and to the host layers via hydrogen bonds, and therefore formamide presumably could not open or penetrate the interlayers in large volume. In contrast, there was not a clear lower threshold for charge occupation of amino acid; even LDH intercalates with charge occupations of less than 1% underwent delamination. Finally, M2+-Al LDH systems other than the Mg−Al system also underwent delamination.