N-Amidothiourea based PET chemosensors for anions

Selective recognition of choline phosphate by tripodal hexa-urea receptors with dual binding sites: crystal and solution evidence

Two tripodal hexa-urea receptors functionalized with aromatic terminal groups are capable of binding choline phosphate (CP). Crystal structures of the host-guest complexes reveal that the zwitterion CP is efficiently encapsulated in the tripodal hosts in a dual-site binding mode. The phosphate tail of CP is coordinated by the urea groups and the quaternary ammonium head is bound in a 'composite aromatic box' through cation-π and hydrogen-bonding interactions. Such a partial aromatic binding environment for the Me3N-+ cation mimics that of most enzymes catalyzing the conversion of quaternary ammonium substrates. Moreover, NMR, ESI-MS, and fluorescence studies demonstrate the selective binding and sensing of CP over other competing species such as ADP, ATP, choline and derivatives.

Colorimetric anion sensors based on positional effect of nitro group for recognition of biologically relevant anions in organic and aqueous medium, insight real-life application and DFT studies

A new six colorimetric receptors A1-A6 were designed and synthesized, characterized by typical common spectroscopic techniques like FT-IR, UV-Visible, ¹H NMR, ¹³C NMR and ESI-MS. The receptor A1 and A2 exhibit a significant naked-eye response towards F^- and AcO^- ions in DMSO. Due to presences of the NO₂ group at para and ortho position with extended π-conjugation of naphthyl group carrying OH as a binding site. Compared to receptor A2, A1 is extremely capable of detecting F^- and AcO^- ions present in the form of sodium salts in an aqueous medium. This is owed to the occurrence of NO₂ group at para position induced in increasing the acidity of OH proton. Consequently, it easily gets deprotonated in aqueous media. The detection limit of receptor A1 was turned out to be 0.40 and 0.35ppm for F^- and AcO^- ions which is beneath WHO permission level (1.0ppm). Receptor A1 shows a solitary property of solvatochromism in different aprotic solvents in presence of AcO^- ion. Receptor A1 depicts high selectivity towards AcO^- ion in DMSO: HEPES buffer (9:1, v/v). Receptor A1 proved itself for real life application by detecting anion in solution and solid state. The binding mechanism of receptor A1 with AcO^- and F^- ions was monitored from ¹HNMR titration and DFT study.

A highly sensitive pyridine-dicarbohydrazide based chemosensor for colorimetric recognition of Cu2+, AMP2−, F− and AcO− ions

A single colorimetric chemosensor for the detection of both Cu²⁺ and AMP²⁻ ions has been developed for the first time.

Colorimetric detection of fluoride ions by anthraimidazoledione based sensors in the presence of Cu(ii) ions

A thioimidazole bearing anthraimidazoledione detects fluoride selectively in the presence of Cu²⁺with a detection limit of 0.04 ppm. The results show that the change of thioimidazole to imidazole leads to no detection.