Design and synthesis of dual probes for detection of metal ions by LALDI MS and fluorescence: application in Zn(ii) imaging in cells

Abstract

A Label-Assisted Laser Desorption/Ionization (LALDI) technique has recently been applied to the detection of metal ions through a time of flight (TOF) mass spectrometric measurement. In this paper, we report the synthesis of two terpyridine based ligands L1 and L2 containing a pyrene moiety. The presence of the latter helped the ligand metal complex to desorb from the surface and ionize upon laser irradiation and finally show up in the TOF MS. Both ligands were able to detect Zn²⁺, Ni²⁺ and Co²⁺ ions while Cu²⁺, Fe²⁺ and Mg²⁺ remained LDI silent. Complexation with the ligands also caused a red fluorescence only with Zn²⁺ ions that allowed Zn²⁺ imaging in cells. Thus the pyrene moiety acted as a dual probe for metal ion detection exploiting both LALDI MS and fluorescence techniques.