Abstract:

Two pyridyl imidazo[4,5-f]1,10-phenanthroline derivates, namely 2-(3-pyridyl)-imidazo[4,5-f]1,10-phenanthroline(G1) and 2-(4-pyridyl)imidazo [4,5-f]1,10-phenanthroline(G2), were synthesized and characterized by elemental analysis, 1H NMR and MS. Under various concentrations of cucurbit[n]urils(Q[n], n=6,7), the interaction of Q[n] with G1 and G2 were studied in buffer solutions with different pH values by using UV-Vis spectroscopy and fluorescence spectrophotometry. The results revealed that cucurbit[n]urils(n=6,7) form a 1∶1 complex with G1, and Q[6] form a 1∶1 complex with G2 in acidic solution, fluorescent sensitizing effects of both Q[6] and Q[7] toward guests were determined. Under acidic solution Q[7] formed a 2∶1 complex with G2, and a fluorescent quenching effect of Q[7] on G2 was observed. Association constants(K) of Q[n](n=6,7) with G1 were found to be 3.00×104 L/mol, 1.86×104 L/mol respectively, while those of Q[n](n=6,7) with G2 are 1.64×104 L/mol and 1.01×103 L/mol respectively. With decreasing acidity of the systems, the interaction between guests and Q[n](n=6,7) weakened and no interaction was observed under neutral conditions.

Key words: phenanthroline derivates, synthesis, Cucurbit[n]urils, Rost-guest inclusion reaction, Spectroscopic method