It is fundamental to study the principles on how to adjust the polymorphic crystals of organic compounds in the fields of pharmaceutics,fuels and pesticides. Theophylline is a kind of methyl purine analogues,and has polymorphic crystals including the form I,II,III,IV and M. Taking into account the structural similarity between adenosine and theophylline,we studied the effect of oligonucleotides containing adenosines on the solution crystallization process of theophylline. The results indicate that adopting ...