1643575-07-8Relevant academic research and scientific papers
PEGylated meso-arylporpholactone metal complexes as optical cyanide sensors in water
Worlinsky, Jill L.,Halepas, Steven,Brueckner, Christian
, p. 3991 - 4001 (2014/06/09)
The colorimetric cyanide sensing ability of free base porpholactone, a pyrrole-modified porphyrin in which a porphyrin β,β′-double bond was replaced by a lactone functionality, and its zinc(ii), platinum(ii), and gallium(iii) complexes in aqueous solution are reported. Water-solubility of the parent meso-pentafluorophenyl-derivatized porphyrinoids was assured by PEGylation of the p-aryl positions using a nucleophilic aromatic substitution reaction with thiol-terminated PEG chains. A central metal-dependent sensing mechanism was revealed: While the CN- adds to the zinc(ii) complex as an axial ligand, resulting in a minor response in its UV-vis spectrum, it undergoes a nucleophilic addition to the lactone moiety in the platinum(ii) and gallium(iii) complexes, leading to a much more prominent optical response. Nonetheless, these chemosensors are less sensitive than many other sensors reported previously, with detection limits at pH 7 for the zinc, gallium, and platinum complexes of 2 mM (50 ppm), 240 μM (6 ppm), and 4 mM (100 ppm), respectively. The gallium(iii) complex is weakly fluorescent (= 0.8%) and cyanide addition leads to fluorescence intensity quenching; the cyanide adduct responds with a fluorescence switch-on response but the signal is weak (-2%). Lastly, we report on the fabrication of a unique optical cyanide-sensing membrane. The PEGylated gallium-complex was incorporated into a Nafion membrane (on a PTFE carrier film). It was shown to be stable over extended periods of time and exhibiting a reversible and selective response within minutes to cyanide, with a 5 mM (130 ppm) detection limit. This largely fundamental study on the ability to utilize the once rare but now readily available class of pyrrole-modified porphyrins as chemosensors highlights the multiple principle ways this chromophore platform can be modified and utilized. This journal is the Partner Organisations 2014.
