hatcher content part 2

how can a cyclic ring of carboxylic acid groups assemble?

close packed, parallel or kagomé (triangular shape)

how can you analyse grids of coordination complexes?

single crystal XRD - molecular structure

electrospray MS - peak for ion corresponding to mass

109Ag NMR - check resonances intensity ratio

when making a mixed metal grid, which metal do you add first?

add the less labile metal first because if you do it the other way round the less labile metal will displace the more labile metal

which metals prefer square planar?

Rh(I), Ir(I), Ni(II), Pd(II), Pt(II), Cu(III), Au(III)

when making squares and triangles, which is favoured when?

with more flexible ligands, there is less selectivity, so can get both in solution

squares are less strained so are enthalpically favoured

there are a smaller number of components in a triangle so they are entropically favoured

at higher concentrations, the square is favoured

sterics favour triangle

why are macrocycles favoured over polymers?

thermodynamics - entropy decreases as polymers form

how can you make rectangles with coordination complexes?

metal centers make up two opposite corners and the other corners are made of a ligand coordinating to both the metal centers

what are catenanes?

supramolecules composed of 2 or more mechanically interlocked macrocycles

first discovered in 1960s

more traditionsl syntheses involve all organic interlocked molecules

how can catenanes be made?

perform ring closing reaction and rely on statistical probability

use supramolecular preorganisation, they self assemble because of preferential intermolecular interactions or template directed synthesis

e.g. through pi pi stacking interactions or metal templating

what are rotaxanes?

supramolecules composed of a rod like molecule (axel) mechanically interlocked onto a macrocycle

rod like molecule is capped by bulky groups (dumbbell shaped)

what are helicates?

made up of metal centers that have ligands that are designed to twist when coorindated to tetrahedral metal centers

ligands for double helicates are linked in the 6,6’ positions (too sterically constrained for binding to octahedral metal centers)

ligands for triple helicates are linked in the 5,5’ positions