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A full account of our studies of 2,4,6-trinitrophenol (TNP) sensing is provided. A series of chemosensors with a variety of aromatic chromophores for specific recognition of TNP has been designed and then realized through the fluorescence "on/off" mechanism. These chemosensors demonstrated highly selective, sensitive, and fluorescent quenching of TNP with remarkable visual changes through the intramolecular charge-transfer (ICT) process. Their host-guest interactions were investigated by (1)H NMR spectroscopic titrations and their corresponding co-crystal structures, which showed that the 1:1 host-guest complexes were formed by multiple hydrogen-bond interactions in solution or in the solid state. The origins of the significant affinity demonstrated during the fluorescence recognition process were further disclosed through DFT calculations of corresponding compounds.

A chiral BINOL derivative bearing Schiff’s base group has been synthesized for the selective fluorescent recognition of Hg2+. Highly selective “turn-on” type fluorescence changes were observed upon the addition of Hg2+. The fluorescence intensity enhancement was ascribed to the complex formation between (R)-1 and Hg2+ which blocked the photo-induced electron transfer process.

In the binuclear title complex, [Ag(2)(C(31)H(22)N(4)O)(2)](ClO(4))(2)·2C(3)H(7)NO, the Ag(I) atom is penta-coordinated by three N atoms from the tridentate chelating terpyridyl group and by one N atom and one O atom from the quinolin-8-yl-oxy group in a distorted square-pyramidal geometry with the O atom at the apical position. The centrosymmetric complex cation involves intra-molecular π-π stacking inter-actions [centroid-centroid distance = 3.862 (4) Å] between the central pyridine and benzene rings. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds result in the formation of a supra-molecular network.

In the title compound, C30H38O4S2, the centroid of the benzene ring lies on a center of inversion. The thiophene ring is aligned at 49.8 (1)° with respect to the benzene ring. The alkyl chain adopts an extended zigzag conformation.

A fluorescent and colorimetric receptor (L) for specific recognition of TNP was described. The origins of this remarkable affinity was disclosed by the crystal structure of corresponding host-guest complex L·TNP.

The molecule of the title compound, C30H24N2O2S4, adopts a Z-shaped conformation. The terminal benzothiazole ring systems are oriented at a dihedral angle of 60.81 (8)°, while the central benzene rings are twisted to each other by a dihedral angle of 13.56 (14)°. Weak intermolecular C—H...π interactions are present in the crystal structure.