| Novel ternary graphite intercalation compounds (GICs) of alkali metal cations and a wide variety of amines have been synthesized by one-pot chemical syntheses. Alkali metals studied includes Li, Na and K. The families of amines employed are nalkylamines, branched alkylamines, and different structural isomers of diamines and polyamines. Intragallery structures of the amine co-intercalates residing between the graphene sheets are proposed based on powder X-ray diffraction (PXRD), supplemented by compositional analyses, thermal analyses, and structure optimization when appropriate.;A homologous series of M-n-alkylamine-GICs (M = Na, Li) is reported for the first time, with the n-alkylamines of 3-14 carbon atoms (nC3-nC14). The following new GICs with indicated stages and intercalate arrangements are obtained: stage 1, di~ 0.70 nm, monolayer (nC3, nC4); stage 1, di ~ 1.10 nm, bilayer (nC6, nC8); and stage 2, di ~ 1.10 nm, bilayer (nC12, nC14). Here di is the gallery height. Two features new to donor-type GICs found are (i) an intercalate bilayer arrangement with guest alkyl chains parallel to encasing graphene layers, and (ii) the transition from an intercalate bilayer to monolayer arrangement upon evacuation for nC6.;GICs containing branched alkylamines co-intercalates are prepared and their intragallery structures compared to those of selected n-alkylamines. A notable difference is observed for amines with 4 carbon atoms. While the linear n-butylamine forms parallel monolayers (di ~ 0.70 nm), the branched analogs (iso-butylamine and sec-butylamine) instead form bilayers with di ~ 1.30 nm. This result contrasts with the general observation that more sterically-hindered intercalates tend to intercalate at lower concentrations. This structural difference is not observed, however, between npropylamine and iso-propylamine (di ~ 0.70 and 0.76 nm respectively).;A rare example of a ternary GIC exhibiting cation-directed orientation of the diamine co-intercalate (1,2-diaminopropane, 12DAP) is reported. Depending on the cation M+, this diamine can exhibit either perpendicular (M = Li, di ~ 0.81 nm), parallel (M = K, di ~ 0.70 nm) or a tilted orientation (M = Na, di ~ 0.75 nm). Interestingly, the gallery expansions increase as the cationic radii decrease.;The structural effect of the diamines is systematically investigated, employing diamines with different alkyl chain lengths, different positions of an --NH2 group, and different --CH3 substituent patterns. The first example of a monolayer perpendicular-to-parallel transition in a GIC is reported for Li-ethylenediamine (EN)-GIC, with the respective change in di from 0.85 to 0.68 nm. The sodium analog, Na-EN-GIC, is also prepared and described. We also report quaternary compounds of mixed cations (Li,Na)-12DAP-GIC and mixed amines Na-(EN,12DAP)-GIC.;Ternary graphite intercalation compounds (GICs) of alkali metals and polyamines are prepared. Structural modifications similar to the diamines indicated above are also observed for polyamine intercalates. The polyamines studied include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, N,N,N',N',N'- pentamethyldiethylenetriamine, and tris(2-aminoethyl)amine. Most of the new GICs have amine intercalates in parallel orientation ( di ~ 0.76-0.86 nm for monolayers, and 1.13 nm for bilayers), though the GIC stage numbers depend on the size of the polyamine. In contrast, the star-shaped polyamine tris(2-aminoethyl)amine shows a perpendicular monolayer orientation with di ~ 1.06 nm. |
