FULL PAPER Novel organometallic chalcones functionalized with a crown ether fragment as optical ion chemosensors Fernando Godoy 1 | Tamara Maldonado 1 | Erick Flores 1 | Nicolás Agurto 1 | Rodrigo González 1 | Guillermo Ferraudi 2 | Graham Lappin 3 1 Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Santiago, Chile 2 Notre Dame Radiation Laboratory, University of Notre Dame, IN 46556 U.S.A. 3 Department of Chemistry and Biochemistry, University of Notre Dame, IN 46556, U.S.A. Correspondence Fernando Godoy and Tamara Maldonado, Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Santiago, Chile. Email: fernando.godoy@usach.cl; tamara.maldonado@usach.cl Funding information Departamento de Investigaciones Científicas y Tecnológicas, Universidad de Santiago de Chile, Grant/Award Number: Postdoc_DICYT Código 021642GG; Fondo de Fomento al Desarrollo Científico y Tecnológico, Grant/Award Number: 21120556 and 21130320; Fondo Nacional de Desarrollo Científico y Tecnológico, Grant/Award Number: 1151156; Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, Grant/Award Number: DE‐ FC02‐04ER15533 We previously reported the synthesis and characterization of new organometal- lic chalcones derived from ferrocene, cyrhetrene and cymantrene functional- ized with a benzo‐15‐crown‐5 fragment. The ferrocene and cyrhetrene chalcones have been investigated as chemosensors for metal ions with optical response in acetonitrile. Several metal ions were selected considering the diam- eter of the cavity and the charge‐to‐radius ratio of the cation. The stoichiometry of the complexes was determined using Job's method. It was found that Na + and Ca 2+ complexes have a 1:1 stoichiometry while a 2:1 (metaloligand‐to‐cat- ion) stoichiometry was determined for Ba 2+ and Pb 2+ complexes. The associa- tion constants were calculated according to the stoichiometry of the complex and the results showed that they are directly affected by the electron‐withdraw- ing nature of the organometallic fragment. Moreover, complexes of ferrocenyl chalcone have larger association constants than those of the cyrhetrenyl ana- logue. This experimental observation is consistent with the electronic proper- ties of the ferrocenyl fragment. KEYWORDS association constant, chemosensor, crown ether, metal ion, organometallic chalcones 1 | INTRODUCTION Metal ions play a fundamental role in biology; for exam- ple, group 1 and 2 metals (alkali and alkaline earth metal ions such as sodium, potassium, calcium and magnesium) are highly abundant in most biological organisms. [1] Metal ions are also involved in chemical processes and environmental pollution. [2] Thus, sensing of ions is an area of intense research activity. [3] Chemosensors are usu- ally constructed by a binding site linked to a signaling unity; in that way, ion coordination is determined by a measurable physical change. Since the pioneering work of Beer et al., there have been a large number of chemosensors derived from ferrocene considering their stability, synthetic feasibility and redox properties. [4] These chemosensors have been functionalized using a Received: 26 July 2017 Revised: 29 August 2017 Accepted: 30 August 2017 DOI: 10.1002/aoc.4115 Appl Organometal Chem. 2017;e4115. https://doi.org/10.1002/aoc.4115 Copyright © 2017 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/aoc 1 of 9