I synthesized PEG-Hematin by the following procedure:

Diethyl azodicarboxylate (240 μl, 0.60 mmol) was added to PEG (0.5 g, 0.25 mmol), triphenylphosphine (160 mg, 0.60 mmol) and hematin (190 mg, 0.30 mmol) suspended in N,N-dimethylformamide (DMF; 10 ml) in a dropwise manner at 0°C under a nitrogen atmosphere.

(Source:http://www.nature.com/pj/journal/v42/n12/full/pj201097a.html)

I would like any input on whether it's possible to further purify PEG-Hematin by crystallization after it has been precipitated by a copious wash with diethyl ether, re-dissolved in acetone and re-precipitated it in more diethyl ether.

I'm still learning about crystallization in my inorganic chemistry class and was wondering if it can be applied to this pegylated porphyrin for purification purposes and possibly x-ray crystallography??

I learned that vapor diffusion can be used in protein crystallization. This needs an inner vial and outer vial. The inner vial contains your compound dissolved in a soluble solvent. The outer vial needs to contain a solvent that the compound is insoluble in, and it needs to have a higher vapor pressure than the inner solvent. A common example is a water-soluble compound dissolved in water in the inner vial, and acetone if the compound is insoluble in acetone (which also has a higher vapor pressure). could this be applicable?