Host-Guest Structures
TOPOTACTIC SOLID-STATE REACTIONS = modifying existing solid state structures while maintaining the integrity of the overall structure
Host dimensionality
3D
2D
ID
OD
1
Intercalation
I Compounds
Layered Compounds
GRAPHITE INTERCALATION
G (s) + K (melt or vapour) —» C8K (bronze)
C8K (vacuum, heat) -^ C24K -^ C36K -^> C48K -^ C60K
Graphite sp2 sigma-bonding in-plane p-7E-bonding out of plane Hexagonal graphite = two-layer ABAB stacking sequence
SALCAOs of the p-7t-type create the valence and conduction bands of graphite, very small band gap, metallic conductivity properties in-plane, 104 times that of out-of plane conductivity
C8K potassium graphite ordered structure
Ordered K guests between the sheets, K to G charge transfer
AAAA stacking sequence, reduction of graphite sheets, electrons enter CB
K nesting between parallel eclipsed hexagonal planar carbon six-rings
3
Layered Compounds
ABABAB
Layered Compounds
Layered Compounds
Exfoliation
Host + Guest    1
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52
HT
Exfoliation
(C4Hg)4N+OH-
a-Zr(HOP03)2 ■ H20 d(001) = 7MÄ
excess^
(C4H9)4N+OH
intercalated solid d(00í) = l6-5Á
Colloid of single layers
7
Layered Compounds
8
Layered Compounds
Layered Compounds
LDH = layered double hydroxides
hydrotalcites
mineral Mg6Al2(OH)16C03.4H20
Brucite layers, Mg2+ substituted partially by Al3+
Layers have positive charge
Layered Compounds
Brucite layers, Mg2+ substituted partially by Al3 Layers have positive charge
(a) [Ca2AI(OH)6]2S04.6H20   (b) [LiAI2(OH)6]CI   (c) [Mg225AI075( OH)6]OH
11
Layered
LDH = layered double hydroxides
hydrotalcites
mineral Mg6Al2(OH)16C03.4H20
Brucite layers, Mg2+ substituted partially by Al3+
Layers have positive charge
Intercalate anions [Cr(C204)3]3_
Compounds
9.9 A
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12
Layered Compounds
the intercalation of methylphosphonic acid into Li/Al LDH
(a) [LiAl2(OH)6]Cl.H20
(b) second-stage intermediate, alternate layers occupied by CI and MPA anions
(c) first-stage product with all interlayer regions occupied by MPA.
13
Layered Compounds
MPS3 (M = V, Mn, Fe, Co, Ni, Zn)
TiS.
a-Zr(HP04)2.H20
14
Layered Compounds
x Li + TiS2 -> LixTiS2
15
3D Intercalation Compounds
Cu3N and Mn3N crystallize in the (anti-) Re03-type structure
the large cuboctahedral void in the structure can be filled By Pd to yield (anti-) perovskite-type PdCu3N By M = Ga, Ag, Cu leading to MMn3N
16
3D Intercalation Compounds
Tungsten trioxide structure
= W06 octahedra joined at their corners
= the perovskite structure of CaTi03 with all the calcium sites vacant
Zn + 2 HCl -> 2 H + ZnCl2
WO3 + x H -> HXW03
The color and conductivity changes are due to the intercalation of protons into the cavities
in the WO3 structure, and the donation of their electrons to the conduction band of the W03
matrix. The material behaves like a metal, with both its conductivity and color being derived
from free electron behavior.
The coloration reaction used in electrochromic displays for sun glasses, rear view mirrors in
cars
Efydrogen Tungsten Bronze
3D Intercalation Compounds
C60=FCC
^3C60