Triazole-linked amidopyrene-tagged fluorometric probe for Au3+ ions and pH control aggregation-induced emission

In this paper, an amidopyrene-tagged reversible fluorescence probe 1 has been constructed for the detection of Au(III) ions in H2O/CH3CN (4/1, v/v). It is used to identify the Au(III) ions over several metal ions with excellent sensitivity (LOD: 0.061 µM). The fluorescence quenching of 1 with Au(III) ions might be attributed to the reverse PET process. Probe 1 recognized Au(III) by forming tetravalent geometry with the amide -NH, triazole moiety, free water, and Cl- ion in 1:1 binding mode, which is evidenced by the DFT calculations, FT-IR spectroscopy, and HRMS value of the complex. The application utility of probe 1 was ascertained from the recovery of Au(III) ions from different sources of natural water samples. Interestingly, molecule 1 also showed aggregation-induced emission behavior at basic pH (>10) in H2O/CH3CN medium with high water content. The AIE might be attributed to the formation of self-associates of 1 upon the intermolecular H-bonding interactions between water and donor atom(s) of 1 or the increased polarity of the solvent medium.

Novel pyrene-calix[4]arene derivatives as highly sensitive sensors for nucleotides, DNA and RNA

Covalent functionalization of a calix[4]arene with one or two pyrene arms at one rim and two imidazoles at the opposite rim of the macrocyclic basket, yields fluorescent conjugates characterized by intramolecular pyrene-calixarene exciplex emission of a mono-pyrene conjugate, whereas the bis-pyrene derivative exhibits pyrene excimer fluorescence. The pyrene emission in these novel compounds is shown to be sensitive to non-covalent interactions with both mono- and polynucleotides. Pyrene-calixarene conjugates, acting as host molecules, strongly interact with nucleotides, as monitored by moderate emission quenching, reaching 0.1 μM affinities, comparable to some of the most effective supramolecular sensors for nucleotides. These compounds are efficiently inserted into ds-DNA/RNA grooves, with a high, 0.1-1 μM affinity, not influencing significantly any of the ds-polynucleotide native properties, whereby complete emission quenching allows the detection of DNA at nM concentration.

Highly selective recognition of the Al(ClO4)3 molecule by a mono-pyrene substituted thiacalix[4]arene chemosensor

A mono-pyrene substituted thiacalix[4]arene chemosensor (TCA-Py) was successfully synthesized in satisfactory yield. Fluorescence analysis revealed that TCA-Py exhibited a high recognition selectivity toward the Al(ClO₄)₃ molecule due to the synergy between the Al³⁺ cation and ClO₄^- anion. This unique ability to recognise an entire inorganic molecule broadens the field of molecular recognition.