Artículo de publicación ISI; A new supramolecular sensitizer for nickel(II) ion in aqueous solution based on a pyridyltriazolopyridine-cyclodextrin inclusion complex is proposed. The inclusion complexation behavior, characterization andbinding ability of pyridyltriazolopyridine (PTP) with dimethyl- -cyclodextrin (DM CD) has been inves-tigated both in solution and solid state by means of absorption, fluorescence,1H NMR, DSC, and molecularmodeling methods. The stoichiometry of the inclusion complex is 1:1, and the thermodynamic studiesindicate that the inclusion of PTP is mainly an entropic driven process. The 2D NMR studies revealed thatthe pyridyl-triazolopyridine is included by both sides of cyclodextrin which are in good agreement withthe docking results. The fluorescence changes upon addition of divalent cations to the inclusion complexindicate a high selectivity and sensitivity for Ni2+by fluorescence quenching in neutral aqueous solution.; Fondecyt 1120142 and to CEPEDEQ from theChemical and Pharmaceutical Science Faculty of the University ofChile for the use of NMR. Ministerio de Ciencia e Innovación (Spain) (Project Consolider-Ingenio Supramed CSD 2010-00065) and to Generalitat Valenciana (Valencia, Spain)(Project PROMETEO 2011/008).