Structural and fluorescent study of zinc complexes of dansyl aminoquinoline

We have shown previously that 8-(5′-N,N-dimethylamino-1′-naphthalene)-sulfonamidoquinoline (DANQUIN) demonstrated a remarkable selectivity and sensitivity for the Zn(II) ion. In this work, the crystal structures of DANQUIN, Cu(DANQUIN)2 and Cu(DANPY)2 (DANPY, N-2-picolyl-(5′-N,N-dimethylamino-1′-naphthalene)-sulfonamide) are reported and compared with the simulated structure of Zn(DANQUIN)2, which is important for the understanding of the factors that govern the fluorescence of DANQUIN. Free DANQUIN mainly displays the fluorescence of the dansyl group at 547 nm while the Zn(II)-DANQUIN complex mainly shows the enhanced fluorescence of aminoquinoline at 469 nm, while the emission of the dansyl group shifted to 517 nm with an almost constant intensity. This result demonstrates the advantage of this hybrid fluorescent chemosensor for Zn(II), and also makes it a potential candidate for ratiometric Zn(II) detection.

Structural analysis reveals that the fluorescent property of metal complexes of DANQUIN and DANPY is mainly determined by the nature of the coordinated metal center, while the coordination mode and geometry of the metal complexes has no evident effects. The fluorescence of the Zn(DANQUIN)2 is mainly arisen from the aminoquinoline moiety.Figure optionsDownload as PowerPoint slide