Interaction of porphyrin and sapphyrin macrocycles with nucleobases and nucleosides; Spectroscopic, quantum chemical and chromatographic investigation

Novel oligopyrrole macrocycle-based sorbents were prepared via amide covalent bonding of carboxylic acids of porphyrin and sapphyrin derivatives to 3-aminopropyl silica. Covalent attachment of Cu(II)-tetraphenylporphyrin formyl-derivative was performed by amine linkage. Prepared sorbents were characterized by Raman spectroscopy and elemental analysis. Retention behavior of nucleobases and nucleosides was investigated by HPLC. UV¯VIS and 1H NMR titrations were used to study the role of oligopyrrol macrocyclic receptors for selective recognition of adenine, cytosine, thymine and uracil and their nucleoside forms. The spectroscopic results were compared with quantum chemical calculations at semiempirical level and with the data obtained by HPLC measurements. Obtained data suggest that an aromatic pi¯pi stacking interactions govern the HPLC separation. A different behavior was found for purine and pyrimidine bases. An introduction of Cu(II) into porphyrin macrocycle led to a dramatic increase of separation efficiency, probably due to an increase of interaction energy.