In recent times I have shown how a lad can have fun with the unit cells of inorganic solids, but now it is time to move onto something with carbon in it. I choose to look at the solid state structure of a polymer which is a high temperature engineering polymer.
LIMMUP in the crystallographic database is Poly((4,4′-diphenylene)pyromellitimide) which was described by Y. Obata, K. Okuyama, S. Kurihara, Y. Kitano and T. Jinda in Macromolecules, 1995, 28, 1547. This is a solid which is an endless chain of atoms covalently linked to the next. Here is a picture of the unit cell.
While here is a picture of five of the polymer chains.
While looking for examples of the polymer chains I noticed something else, this brings me onto another subject. I hold the view that one of the first steps to maturity is the point at which a person truly accepts that things which they are not interested in, involved in or have experience in can be truly worthwhile and valid. I have to add the warning that there is some work out there which is not worthwhile and is frankly close to worthless, but I do not want to point the finger by naming names well at least not today.
I have spent much of my life working on trying to get molecules to selectively recognise metals; I used to share an office with a man (Zhixue Zhu) who worked for Howard Colquhoun on a project where he was trying to get molecules to recognise short parts of polymer chains. While it might not have been quite the sort of thing that I have done in life, I still hold the view that the work is good work which is worthwhile.
Here what Dr Zhu did was to use a pair of pyrene groups to recognise part of a short chain model of kapton (poly(4,4′-oxydiphenylene-pyromellitimide)); his tweezers recognized the pyromellitimide part of the chain. Here is a picture of the solid which he published in Chemical Communications, 2004 page 2650 together with H.M. Colquhoun, C.J. Cardin and Yu Gan.
I suspect that Christine Cardin found this solid interesting as her group have done a lot of work in the past on how things like acridines bond onto DNA through pi-pi effects.