Molecular recognition of creatinine

A host-guest system involving derivatives of 2-amino-4(3H)-pyrimidone and creatinine was developed. ¹H NMR and ¹³C NMR experiments give evidence of complex formation. A geometry optimization with Gaussian 88 suggests a complex structure in which the 5-membered and the 6-membered heteroring are connected by one long and two shorter hydrogen bonds. The hosts described strongly enhance the extraction of creatinine from its aqueous solution into CH₂Cl₂ and CDCl₃. As the creatinine concentration in the organic solvents may be determined by measuring the changes in the UV spectrum of the hosts upon complexation, derivatives of 2-amino-4(3H)-pyrimidone may eventually be used in optical creatinine sensors.