1 Host-Guest Structures TOPOTACTIC SOLID-STATE REACTIONS = modifying existing solid state structures while maintaining the integrity of the overall structure Host dimensionality 3D 2D 1D 0D 2 Layered Compounds Intercalation 3 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--bonding out of plane Hexagonal graphite = two-layer ABAB stacking sequence SALCAOs of the p--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 4 Layered Compounds ABABAB 5 Layered Compounds 6 Layered Compounds Exfoliation Host + Guest 7 Exfoliation 8 Layered Compounds 9 Layered Compounds 10 Layered Compounds LDH = layered double hydroxides hydrotalcites mineral Mg6Al2(OH)16CO3.4H2O Brucite layers, Mg2+ substituted partially by Al3+ Layers have positive charge 11 Layered Compounds Brucite layers, Mg2+ substituted partially by Al3+ Layers have positive charge (a) [Ca2Al(OH)6]2SO4.6H2O (b) [LiAl2(OH)6]Cl (c) [Mg2.25Al0.75( OH)6]OH 12 Layered Compounds LDH = layered double hydroxides hydrotalcites mineral Mg6Al2(OH)16CO3.4H2O Brucite layers, Mg2+ substituted partially by Al3+ Layers have positive charge Intercalate anions [Cr(C2O4)3]3- 13 Layered Compounds the intercalation of methylphosphonic acid into Li/Al LDH (a) [LiAl2(OH)6]Cl.H2O (b) second-stage intermediate, alternate layers occupied by Cl and MPA anions (c) first-stage product with all interlayer regions occupied by MPA. 14 Layered Compounds MPS3 (M = V, Mn, Fe, Co, Ni, Zn) TiS2 -Zr(HPO4)2.H2O 15 Layered Compounds x Li + TiS2 LixTiS2 16 3D Intercalation Compounds Cu3N and Mn3N crystallize in the (anti-) ReO3-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 17 3D Intercalation Compounds Tungsten trioxide structure = WO6 octahedra joined at their corners = the perovskite structure of CaTiO3 with all the calcium sites vacant 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 WO3 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 Zn + 2 HCl 2 H + ZnCl2 WO3 + x H HxWO3 18 3D Intercalation Compounds C60 = FCC K3 C60