Porphyrin-rhodamine conjugates as new materials with sensing ability.

Conjugates based on porphyrin (porph) and rhodamine (rh) moieties linked by amide bonds, dyad 1 (porph-spacer-rh) and triad 2 (porph-spacer-rh-spacer-porph), were prepared respectively from precursor 1 and precursor 2 . The sensing ability of precursor 1 , dyad 1 and triad 2 towards the divalent metal ions Cu 2+ , Zn 2+ , Cd 2+ , Pb 2+ , Hg 2+ and the monovalent Hg + was explored in solution by absorption and fluorescence spectroscopy as well as in gas phase using matrix-assisted laser desorption/ionization (MALDI)-TOF mass spectrometry. In solution one-metal-per-ligand molar ratio was obtained with precursor 1 and triad 2 , however, a two-metal-per-ligand molar ratio was observed with dyad 1 . Additionally, the results obtained by MALDI-TOF-MS confirmed the gas-phase sensing abilities of dyad 1 towards all metal ions tested and of triad 2 towards Zn 2+ . Computational DFT calculations confirm the same stoichiometry. [ABSTRACT FROM AUTHOR]