Synthesis and evaluation of a novel fluorescent sensor based on hexahomotrioxacalix[3]arene for Zn2+ and Cd2+

Abstract

A novel type of selective and sensitive fluorescent sensor having triazole rings as the binding sites on the lower rim of a hexahomotrioxacalix [3]arene scaffold in a cone conformation is reported. This sensor has desirable properties for practical applications, including selectivity for detecting Zn2+ and Cd2+ in the presence of excess competing metal ions at low ion concentration or as a fluorescence enhancement type chemosensor due to the cavity of calixarene changed from a "flattened-cone" to a more-upright form and inhibition of PET. In contrast, the results suggested that receptor 1 is highly sensitive and selective for Cu2+ and Fe3+ as a fluorescence quenching type chemosensor due to the photoinduced electron transfer (PET) or heavy atom effect.

Supramolecular Luminescent Sensors

“…1150 In another example, trioxacalix [3]arene 35 bearing anthracenyl units was synthesized by Jiang et al (Figure 40). 1151 Although this macrocycle demonstrated inherently weak fluorescence in the uncomplexed state due to PET, it was able to detect Cd 2+ and Zn 2+ via fluorescence increases, with a detection limit of 0.38 μM for the latter in acetonitrile. 1:1 binding stoichiometries were observed for both systems, and Benesi−Hildebrand binding constants of 35 with Cd 2+ and Zn 2+ were reported to be 4.06 × 10 4 and 1.44 × 10 4 M −1 , respectively.…”

Argentivorous Molecules with Chromophores in Side Arms: Silver Ion-Induced Turn On and Turn Off of Fluorescence

“…Excimer is defined as a dimer associated with an excited electronic state and dissociative in its ground electronic state. − Generally, the excimer band shows a red shift compared with a monomer because of the increasing electron affinity of the acceptor and decreasing the donor’s ionization potential. − Using the fluorescence properties of excimers, the fluorescent sensor molecules for heavy and transition metals have been extensively developed. − Among well-known fluorophores, anthracene, pyrene, and their derivatives have been investigated into many functions for sensing metal ions, pH, simple inorganic anions, and small organic molecules. − Pyrene is strong electron donor material, and pyrene excimer from several pyrene derivatives usually exhibits a similar emission color of sky-blue or cyan, resulting from almost the same excited-state geometry. − Since excellent monomer and excimer emission changes occur at remarkably different wavelengths on the basis of the distance between two anthracene or pyrene moieties, both fluorophores (anthracene and pyrene) acting as a fluorophore have been utilized effectively. − …”

A Hexahomotrioxacalix[3]arene-Based Ditopic Receptor for Alkylammonium Ions Controlled by Ag+ Ions

“…Shinkai et al reported a series of calix[4]arene-crown-4 derivatives, among which a partial-cone derivative exhibits an exceptional Na + /K + selectivity, as determined by ion-selective electrodes (ISEs) [ 23 ]. We also have developed a series of triazole-derived chemosensors for selective binding of heavy metal ions based on hexahomotrioxacalix[3]arene and thiacalix[4]arene scaffolds [ 26 , 27 , 28 ]. For example, chemosensors derived from hexahomotrioxacalix[3]arene appended at the lower rim with pyrenyl groups via triazole linkers exhibited a highly selective affinity for the Pb 2+ cation through enhancement of the monomer emission of the pyrene moiety in both organic and organic-aqueous solution [ 26 ].…”