Phosphorus-supported multidentate coumarin-containing fluorescence sensors for Cu2+

Phosphorus hydrazides PhP(O)[N(Me)NH2](2), (S)P[N(Me)NH2](3), and N3P3[N(Me)NH2](6) were condensed with 7-diethylaminocoumarin-3-aldehyde (RCHO) to afford the corresponding hydrazones PhP(O)[N(Me)N=CHR](2) (1), (S)P[N(Me)N=CHR](3) (2), and N3P3[N(Me)N=CHR]6 (3). The structural characterization of 1-3 was carried out by their HRMS, H-1 and P-31{H-1} NMR spectra. The molecular structure of 2 was established by a single-crystal X-ray analysis. Interaction of 1 and 2 with various transition metal ions revealed substantial fluorescence enhancement upon interaction with Cu2+ enabling a selective detection mechanism for this metal ion. However, such a fluorescence enhancement was not observed in the case of 3. A 1:1 complex [2 center dot Zn][CIO4](2)center dot 4CH(2)Cl(2) was isolated in the reaction of 2 with Zn(CIO4)(2)center dot 6H(2)O. The molecular structure of this complex revealed that the Zn-II is encapsulated by the ligand utilizing a 3N, 3O coordination set. (C) 2009 Elsevier Ltd. All rights reserved.