Strategic Design of a 2,6-Disubstituted Pyridine-based Probe having Hard-Soft Centers: Responsive Divergence from One Core

Alkyne is a versatile functional group in organic chemistry, and is able to undergo a wide variety of reactions and interactions. Featuring a reactive functional group, alkyne participates in many...

Electronic structure and bridge geometric distortion in push–pull imine-bridged triads. A theoretical study

Intramolecular electron transfer (IET) in imine-bridged triads is studied by analyzing electric charge distribution and ferrocene and bridge distortion parameters.

Metal-coordination driven intramolecular twisting: a turn-on fluorescent-redox probe for Hg2+ ions through the interaction of ferrocene nonbonding orbitals and dibenzylidenehydrazine

A unique C2 symmetric azine bridged bi-ferrocenyl receptor has been designed and synthesized for the selective detection of Hg²⁺ ion with a low detection limit as 15 nM via turn on fluorescence with a blue shift.

Zr-Based MOFs integrated with a chromophoric ruthenium complex for specific and reversible Hg2+ sensing

A novel metal-organic framework of RuUiO-67 was successfully fabricated and exploited as a chemical sensor for the colorimetric detection of Hg2+. The chromophoric Ru complex in RuUiO-67 was designed as a Hg2+ recognition site and a signal reporter. The elaborated probe exhibited a rapid colorimetric response, high selectivity, and sub-micromolar sensitivity for Hg2+ detection.

The structure of Cu(II) and Hg(II) complexes of bispyrenyl azine revisited

Azine ligands show preference for the antiperiplanar conformation, but their 2:2 ligand-metal complexes can exhibit a central N₄M₂ core in the most stable chair arrangement, as in the case of the model lithium complex, with the ligand displaying a synclinal conformation that is not stable in the free ligand. According to DFT calculations, complexation of Cu²⁺ with bis(1-pyrenyl)azine (1) affords a C₂-symmetric [1·Cu²⁺]₂ species with a planar central N₄Cu₂ core exhibiting a weak cuprophilic interaction. The pendant pyrenyl substituents are brought close and parallel to each other, therefore accounting for the π-stacking that is responsible for excimer fluorescence. In case of Hg²⁺, complexation by the same ligand affords a C₂-symmetric complex with an essentially linear N-Hg-C coordination environment at every metal center and without intermetallic interaction. T-Stacking interactions between pyrenyl groups explain the overall rigidity required for enhancement of fluorescence. Graphical abstract The structures of 2:2 complexes of Hg(II) and Cu(II) with bispyrenyl azine are reported.

Recent highlights in mixed-coordinate oligophosphorus chemistry

This review aims to highlight and comprehensively summarize recent developments in the field of mixed-coordinate phosphorus chemistry. Particular attention is focused on the synthetic approaches to compounds containing at least two directly bonded phosphorus atoms in different coordination environments and their unexpected properties that are derived from spectroscopic and crystallographic data. Novel substance classes are discussed in order to supplement previous reviews about mixed-coordinate phosphorus compounds.

Bis(carbazolyl)ureas as selective receptors for the recognition of hydrogenpyrophosphate in aqueous media

Recognition properties of the novel bis(carbazole) tris-ureidic-based receptors 1 and 2 toward different anions have been studied by (1)H NMR and absorption and emission spectroscopy, as well as by DFT calculations. Receptor 1, in which the two urea-functionalized arms are decorated with p-nitrophenyl rings, behaves as a highly selective chromogenic molecular probe for hydrogenpyrophosphate anion in a competitive medium (acetonitrile/water, 70/30). Receptor 2, bearing two urea arms decorated with photoactive pyrenyl rings, acts as a highly selective fluorescent molecular probe for hydrogenpyrophosphate anion in either acetonitrile or an aqueous mixture (acetonitrile/water, 85/15). Receptor 2 exhibits a dual monomer-excimer emission spectrum and undergoes a remarked ratiometry in acetonitrile in the presence of hydrogenpyrophosphate: the excimer band disappears, whereas the monomer band is slightly increased. However, in the aqueous mixture, a strong increase of the excimer emission band was observed, while the monomer emission bands remained almost unaffected. The resulting binding modes and spectroscopic features are explained by suitable structures of model complexes for both receptors. In such complexes, a peripheral cooperative effect was found, alleviating the excess of negative charge in the guest toward the outer surface of the host, as well as the required enlargement on its internal cavity.