Metal Complexes as Receptors

Delgado‐Pinar, Estefanía; Garcı́a-España, Enrique; Verdejo, Begoña; Pitarch‐Jarque, Javier

doi:10.1016/b978-0-12-409547-2.12530-2

Cited by 1 publication

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“…Cryptands and their corresponding metal complexes, cryptates, are versatile supramolecular structures that have proven to be efficient in CO 2 capturing and storage [24] and anion recognition [25]. These preorganized supramolecular structures are key when evaluating their selectivity towards a certain substrate; this has been reviewed by others [26,27]. Following our previous report on CO 2 reduction to CO and CH 4 using a Co(II) cryptate [28], and the proof that cryptands can be stably adsorbed on highly oriented pyrolytic graphite (HOPG) electrode surfaces [29], we investigated the functionalization of HOPG electrodes with cryptands/cryptates, using diazonium salts.…”

Section: Introductionmentioning

confidence: 99%

Cryptand-Functionalized Highly Oriented Pyrolytic Graphite Electrodes

et al. 2021

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Reproducible materials that have detection properties towards a certain molecule are very important for applications in the fabrication of devices. Among all the substrates that are used, highly oriented pyrolytic graphite allows to clearly image a monolayer. On the other hand, cryptand molecules are versatile because they can sense certain analytes with high selectivity. The highly oriented pyrolytic graphite electrode was first functionalized with an aryl bearing a bromine or an alkyne group to further attach cryptand molecules to its surface. The functionalization was performed through the electroreduction of aryl diazonium salts. While functionalization with an aryl-bromine produced a 20 nm-thick dendritic layer, functionalization of the surface with an aryl bearing a terminal alkyne produced a 9.7 nm-thick multilayer. However, if the diazonium salt is prepared in situ, a 0.9 nm monolayer with aryl–alkyne groups is formed. The alkyne functionalized electrode reacted with a bromo-cryptand through a Sonogashira C–C coupling reaction yielding electrodes functionalized with cryptands. These were immersed in a solution of a Co(II) salt resulting in Co(II)-cryptate modified electrodes, highlighting the ability of the cryptands’ modified electrode to sense metal ions. The electrode surface was analyzed by X-ray photoelectron spectroscopy after each modification step, which confirmed the successful functionalization of the substrate with both the cryptand and the cryptate. Cyclic voltammetry studies showed stable current response after approximately six cycles. Different reduction processes were detected for both cryptand (−1.40 V vs. SCE) and cryptate (−1.22 V vs. SCE) modified highly oriented pyrolytic graphite.

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