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Three new triazine compounds [Co 1.5 (H 3 TDPAT)(H 2 O) 3 ]·6H 2 O ( 1 ), [Co 2 (TCPT)(μ 2 -H 2 O) 2 ]·OH ( 2 ), and [Ni 3 (TCPT)]·3OH ( 3 ) were designed and synthesized via the reaction of the symmetrical triazine ligand connected by C-N-C and C-O-C bonds with triazine poly(carboxylic acid)s ligands as the side arms: H 6 TDPAT (H 6 TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) and H 3 TCPT (H 3 TCPT = 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine) as well as the corresponding metal salts under the solvothermal condition. Three triazine polycarboxylate frameworks were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and solid fluorescent spectra in detail. The structural analysis results showed that the three-dimensional porous cage framework of compound 1 was constructed by three different polyhedral cages connected with [Co(COO) 4 (H 2 O) 2 ] building blocks. One of the compounds, 2 , is formed by twin propeller Co 2 (μ 2 -H 2 O)(COO) 3 building blocks connecting two-dimensional layers and the intermolecular π-π interactions involved the triazine rings between the layers. While the structure of compound 3 is similar to that of 2 , assembly is by Ni(COO) 3 building blocks and adjacent layers of the face-to-face π-π interaction between the triazine rings. In order to explore functional properties, the catalytic reduction of p -nitrophenol (PNP) of compounds 1 - 3 was investigated. They exhibit excellent catalytic activity of more than 95% for reduction of PNP with a dose of 2.5 mg of the compounds.

Three new metal-organic frameworks (MOFs), namely, [Pb 7 (TTPCA) 4 Cl 2 ]·3H 2 O ( 1 ), [Pb 7 (TTPCA) 4 (DMA) 2 (HCOO) 2 ]·H 2 O ( 2 ), and [Pb 4 (TTPCA) 3 ]·3DMF·2H 2 O·H 3 O ( 3 ), were synthesized by the H 3 TTPCA ligand [H 3 TTPCA = 1,1',1″-(1,3,5-triazine-2,4,6-triyl)-tripiperidine-4-carboxylic acid], with lead(II) nitrate under solvothermal conditions. They were characterized by CHN analysis, IR spectroscopy, UV-vis spectroscopy, and single-crystal and powder X-ray diffraction. In addition, their thermogravimetric analysis and fluorescence properties were studied. Compounds 1 - 3 were 3D MOF structures with different Pb x (COO) y clusters: ([Pb 7 (COO) 12 Cl 2 ]), ([Pb 7 (COO) 12 ]), and [Pb 8 (COO) 18 ]. Fluorescence detection of compounds 1 - 3 shows that they can act as excellent sensors of nitrophenols with a low limit of detection and a high quenching constant.

Organic aromatic amines are widely used in various fields such as pharmaceuticals, pesticides, dyes, and tobacco smoke. The pollution of organic amines has become a problem that cannot be ignored, due to the extensive harmful effects on the environment and public health, which has become one of the most concerned frontier fields in the world. Identifying and microdetecting o -phenylenediamine (OPD), m -phenylenediamine (MPD), and p -phenylenediamine (PPD) using MOFs have rarely been reported. On the basis of the blue emission properties of Cu-TBDA constructed with 5,5'-((6-chloro-1,3,5-triazine-2,4-diyl)bis(azanediyl))diisophthalic acid (H 4 TBDA) ligand, Cu-TBDA was studied primarily to identify and detect aromatic diamine family as a multifunctional chemical sensor. Interestingly, Cu-TBDA has a very high selectivity and sensitivity to OPD and MPD with a low limit of detection (5.00 μM for OPD and 1.77 μM for MPD). Especially for OPD, Cu-TBDA has a unique switching function for it. When the concentration of OPD is less than 9.1 × 10 -4 M, the fluorescence response of Cu-TBDA suspension exhibit enhanced. However, when the concentration of OPD is more than 9.1 × 10 -4 M, the emission intensity displays quenching phenomenon. Therefore, Cu-TBDA as a chemical sensor not only has recognition and detection functions for organic aromatic amines but also first exhibits turn-on and -off sensing behavior toward OPD.

A series of novel metal-organic frameworks were synthesized by using semirigid ligand 1,1',1″-(1,3,5-triazine-2,4,6-triyl)tripiperidine-4-carboxylic acid (H 3 TTPCA) and lead halide (Cl, Br, or I). The three complexes were characterized by elemental analysis, infrared spectroscopy, ultraviolet-visible spectroscopy, powder X-ray diffraction analysis, and thermogravimetric analysis. X-ray single-crystal diffraction analysis demonstrated that all three complexes were three-dimensional inorganic-organic framework structures with Pb-X 2 (X = Cl, Br, or I). However, slight differences in the chemical environment were the focus of the coordinated halogen atoms and the different compositions of metal oxygen clusters: [Pb 7 (COO) 12 Cl 2 ], [Pb 7 (COO) 12 Br 2 ], and [Pb 7 (COO) 12 I 2 ]. Because of the fluorescence of the organic ligand, the three complexes showed similar photoluminescence properties at room temperature, but the intensity of emissions decreased gradually with an increase in the atomic radius of coordinated halogen atoms. Interestingly, in the fluorescence response tests, complexes 1 and 2 displayed an optical signal of fluorescence "turn-on" while complex 3 showed an optical signal of fluorescence "turn-off". Here we aim to provide a possible mechanism to explain these unique and contradictory luminescence results.