Intercalation Of Guests Research Articles

Preferential anion exchange intercalation of pyridinecarboxylate and toluate isomers in the layered double hydroxide [LiAl2(OH)6]Cl·H2O

All isomers of both pyridinecarboxylate (2-PA; 3-PA and 4-PA) and toluate (o-TA; m-TA and p-TA) can be intercalated into the layered double hydroxide [LiAl2(OH)6]Cl·H2O in water or a water–ethanol mixture at RT to give the fully ion-exchanged first stage intercalation compounds [LiAl2(OH)6]·G·yH2O (G = 2-PA; 3-PA; 4-PA; o-TA; m-TA and p-TA; y = 2.5–3.5). Experiments also showed that using a mixed ethanol–water solvent may improve the crystallinity and decrease the production of Al(OH)3. The observed interlayer separations for the intercalates vary from 14.9 A for [LiAl2(OH)6](4-PA)·3H2O to 16.7 A for [LiAl2(OH)6](p-TA)·2.5H2O. When [LiAl2(OH)6]Cl·H2O is added to a solution containing an equal concentration of two or three isomers of either pyridinecarboxylate or toluate anions, the host exhibits preferential anion-exchange intercalation. Following a series of competitive intercalation reactions involving two or three component mixtures we were able to determine the preference order for intercalation of both PA and TA guests in [LiAl2(OH)6]Cl·H2O. The order was found to be 4-PA > 2-PA > 3-PA and p-TA > m-TA > o-TA in water at both 20 and 80 °C.

Homoleptic Cuprates(II) with Multiply Deprotonated α‐Cyclodextrin Ligands

AbstractIn the presence of cupric ions, α‐cyclodextrin (α‐CD) is multiply deprotonated in alkaline aqueous solution. With lithium or sodium as the counterions, trinuclear sandwich‐type cuprate ions of the formula [Cu3(α‐CDH_6)2]6‐ are formed (1 and 2), whereas dinuclear [Cu2(α‐CDH_4)2]4‐ ions are isolated in the form of the potassium (3a) and the rubidium salts (3b). The structures of the cyclodextrinatocuprate ions resemble cylinders, since the usual conical shape of a cyclodextrin is altered due to the formation of shorter hydrogen bonds on the O2/O3 rim of the α‐cyclodextrin torus. Despite anion formation, the cavity of the cyclodextrin is still hydrophobic, giving rise to the intercalation of acetone guests in 2 and 3.

Relatively isotropic superconductivity at 8.3 K in the Lamellar organometallic intercalate SnSe2{Co(η‐C5H5)2}0.3

Superconductivity in SnSe2{Co(ν‐C5H5)2}0.3 is notable for its high transition temperature—teh highest of any known organometallic intercalate—and because it is more three‐dimensional and less anisotropic than in any other previously reported intercalate. While intercalation of organometallic guests into layered 5d transition metal dichalcogenides causes large increases in the anisotropy of the electronic properties, in SnSe2 the anisotropy is reduced. The critical properties of the superconducting state of this material, including their anisotropy, have been studied in order to investigate the origins of electron pairing in this system.