Bis(2-pyridylmethyl)alkyl(thioalkyl)diamines as promising scaffolds for the construction of fluorescent and redox chemosensors for transition and post-transition metal ions

N,N'-Bis(2-pyridylmethyl)propylendiamine (1) and N,N'-bis(2-pyridylmethyl)-1,5-diamino-3-thiapentane (2) have been functionalised at the secondary nitrogen atoms with dansylamidoethyl (L-1, L-3), 2-quinolinylmethyl (L-2, L-4) and ferrocenylmethyl (L-6, L-7) pendant arms with the intention to study their potentiality as receptor units in molecular sensors. The optical response of L-1-L-4 to the presence of the metal ions Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ has been investigated in MeCN/H2O (4: 1 v/v) solution. The electrochemical response of L-6 and L-7 to the presence of the same metal ions has been investigated in anhydrous MeCN/CH2Cl2 10: 1 (v/v) solution. Results are compared and discussed with the aim to clarify the mutual role played by the bis(2-methylpyridyl)alkyl(thioalkyl)diamines and the signalling units attached to them in reaching the selectivity of the responses observed. (C) 2011 Elsevier B.V. All rights reserved.