Xue-Kai Jiang

Solvent effect and fluorescence response of the 7-tert-butylpyrene-dipicolylamine linkage for the selective and sensitive response toward Zn(II) and Cd(II) ions

The different binding behaviour of 7-tert-butylpyrene based chemosensors bearing dipicolylamine (Dpa) linkages at the 1,3-positions was investigated in various solvents for the sensing of Zn(II) and Cd(II).The potential mono-chelating ligand L1 follows the same binding pattern in both THF and methanol–water solvent systems, exhibiting higher selectivity and sensitivity for Cd(II) over Zn(II) mainly in THF solvent system. The potential bis-chelate ligand L2 can selectively bind both Zn(II) and Cd(II) in a 1:1 ratio in THF, whereas in methanol–water (7:3) at pH = 7.0; a 1:2 binding ratio was observed. In THF, two sites of ligand L2 can only selectively and sensitively bind one Zn(II) or Cd(II). The different complexation behaviour of L1 and L2 in different solvents were studied by means of fluorescence spectra and 1H-NMR titration experiments in the presence of Zn(II) and Cd(II).

Click-modified hexahomotrioxacalix[3]arenes as fluorometric and colorimetric dual-modal chemosensors for 2,4,6-trinitrophenol.

A new type of chemosensor-based approach to the detection of 2,4,6-trinitrophenol (TNP) is described in this paper. Two hexahomotrioxacalix[3]arene-based chemosensors 1 and 2 were synthesized through click chemistry, which exhibited high binding affinity and selectivity toward TNP as evidenced by UV-vis and fluorescence spectroscopy studies. (1)H NMR titration analysis verified that CH⋯O hydrogen bonding is demonstrated as the mode of interaction, which possibly facilitates effective charge-transfer.

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

A receptor cone-1 based on a hexahomotrioxacalix[3]arene bearing three pyridyl groups was successfully synthesized, which has a C3-symmetric conformation and is capable of binding alkylammonium and metal ions simultaneously in a cooperative fashion. It can bind alkylammonium ions through the π-cavity formed by three aryl rings. This behaviour is consistent with the cone-in/cone-out conformational rearrangement needed to reorganize the cavity for endo-complexation. As a C3-symmetrical pyridyl-substituted calixarene, receptor cone-1 can also bind an Ag+ ion, and the nitrogen atoms are turned towards the inside of the cavity and interact with Ag+. After complexation of tris(2-pyridylamide) derivative receptor cone-1 with Ag+, the original C3-symmetry was retained and higher complexation selectivity for n-BuNH3+ versus t-BuNH3+ was observed. Thus, it is believed that this receptor will have a role to play in the sensing, detection, and recognition of Ag+ and n-BuNH3+ ions.

An Unprecedented Photochemical Reaction for Anthracene‐Containing Derivatives

A series of anthracene-containing derivatives have been synthesised and characterised. The photochemical behaviour of these derivatives have been investigated by 1 H NMR spectroscopy. An unprecedented photolysis reaction for anthracene-containing derivatives was observed in the case of anthracenes directly armed with a -CH2 O-R group upon UV irradiation. The photolysis reaction process has been demonstrated to occur in three steps. Firstly, the anthracene-containing derivatives are converted into the corresponding endoperoxide intermediate upon UV irradiation in the presence of air; then, the endoperoxide intermediate is decomposed to the corresponding starting compound and 9-anthraldehyde; finally, 9-anthraldehyde is further oxidised to anthraquinone. Additionally, the photolysis reaction of anthracene-containing derivatives is significantly promoted in the presence of a thiacalix[4]arene platform.