A new 8-hydroxyquinoline-based chemosensor possessing a semirigid structure was designed, and its fluorescent sensing behavior toward metalions was investigated. A prominent fluorescence enhancement only for Cd(2+) was found in aqueous methanol solution. The results clearly suggest that the specific semirigid structure could selectively accommodate Cd(2+) according to ionic radius, which would effectively suppress the intramolecular radiationless transitions from the n pi* state to enhance the fluorescence response.

A new Zn(2+) fluorescent chemosensor N'-(3,5-di-tert-butylsalicylidene)-2-hydroxybenzoylhydrazine (H(3)L(1)) and its complexes [Zn(HL(1))C(2)H(5)OH](∞) (1) and [Cu(HL(1))(H(2)O)]CH(3)OH (2) have been synthesized and characterized in terms of their crystal structures, absorption and emission spectra. H(3)L(1) displays high selectivity for Zn(2+) over Na(+), K(+), Mg(2+), Ca(2+) and other transition metal ions in Tris-HCl buffer solution (pH = 7.13, EtOH-H(2)O = 8 : 2 v/v). To obtain insight into the relation between the structure and selectivity, a similar ligand 3,5-di-tert-butylsalicylidene benzoylhydrazine (H(2)L(2)), which lacks the hydroxyl group substituent in salicyloyl hydrazide compared with H(3)L(1), and its complex [Zn(2)(HL(2))(2)(CH(3)COO)(2)(C(2)H(5)OH)] (3), [Co(L(2))(2)][Co(DMF)(4)(C(2)H(5)OH)(H(2)O)] (4), [Fe(HL(2))(2)]Cl·2CH(3)OH (5), have also been investigated as a reference. H(3)L(1) exhibits improved selectivity for Zn(2+) compared to H(2)L(2). The findings indicate that the hydroxyl group substituent exerts an effect on the spectroscopic properties, complex structures and selectivity of the fluorescent sensor.

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A reddish orange emissive long afterglow phosphor Ca2SnO4:Sm3+ was prepared by solid-state reaction in air atmosphere and characterized by photoluminescence, long-lasting phosphoresce. The afterglow time is more than 7 h which is the longest red or reddish orange long afterglow phosphor at the present time. The phosphorescence mechanism of the long afterglow phosphor was studied by thermoluminescence and positron annihilation lifetime experiments. The defects VCa″, structure defects Sn3+ and Sn2+ may act as hole trapping centers while the defects SmCa⋅ may act as electron trapping centers, and trapping centers play an essential role for photoenergy storage in persistent phosphors.

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A bi-phosphonate ligand tetraethyl-(2,3,5,6-tetramethyl-1,4-phenylene) bis(methylene)diphosphonate has been designed and synthesized. The bi-phosphonate as a bridging ligand reacts with lanthanide nitrates forming four different types of 1D coordination complexes: ribbon polymer (type I), semi-ribbon polymer (type II), zigzag polymer (type III), and dinuclear-triligand short chain (type IV), which changed according to the decrease of the radius of the lanthanide. They have been characterized by IR spectroscopy, elemental analysis, and X-ray diffraction spectroscopy. The photophysical properties of Sm(3+), Eu(3+), Tb(3+) and Dy(3+) complexes at room temperature were also investigated. They exhibit strong fluorescence by excitation of the Ln(3+) ion absorption bands and the quantum yield values of Eu(3+) and Tb(3+) complexes are no less than 20%.