Preparation and ion recognition features of porphyrin–chalcone type compounds as efficient red-fluorescent materials†
A series of porphyrins containing an α,β-unsaturated ketone unit in a β-pyrrolic position (4a–e) were synthesized and characterized. Their sensing ability towards Ag+, Cu2+, Zn2+, Cd2+, and Hg2+ was evaluated in solution by absorption and fluorescence spectroscopy and in the gas phase using MALDI-TOF-MS spectrometry. The versatility of these types of compounds towards other metals was also analysed by studying the behaviour of compound 4d in the presence of Na+, K+, Tl+, Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Pb2+, Fe2+, Fe3+, Cr3+ and Al3+. Polymeric films of polymethylmethacrylate (PMMA) doped with ligand 4d were prepared and their ability to be used as metal ion-probes in the solid state was studied. Compounds of type 4 showed the best performance to be analytically used in developing new Zn2+ ratiometric molecular devices.