Construction of a triazine polycarboxylate Co-MOF with flexible and rigid coordination arms as well as excellent catalytic reduction and adsorption properties.

A new compound [Co2(H2BATD)(DMF)2]·2.5DMF·0.5H2O (1) was synthesized from the triazine ligand H6BATD (H6BATD = 5,5'-(6-biscarboxymethylamino-1,3,5-triazine-2,4-diyl) bis (azadiyl), DMF = N,N-dimethylformamide) and Co(NO3)2·6H2O. Compound 1 was characterized using infrared spectroscopy, UV-vis spectroscopy, PXRD, and thermogravimetry. The three-dimensional network of compound 1 was further constructed using [Co2(COO)6] building blocks from the flexible coordination arms and the rigid coordination arms from the ligand. In terms of functional properties, compound 1 can be used for the catalytic reduction of p-nitrophenol (PNP) to p-aminophenol (PAP), and compound 1 with a dose of 1 mg showed good catalytic reduction properties, as well as a conversion rate of over 90%. Based on the unique π-electron wall and carboxyl groups in the H6BATD ligand that provide abundant adsorption sites, compound 1 can be used to adsorb iodine in cyclohexane solution.

Cu(II) and Zn(II) frameworks constructed by directional tuning of diverse substituted groups on a triazine skeleton and supermassive adsorption behavior for iodine and dyes.

The controllable design, synthesis and functional properties of a series of triazine tetratopic carboxylic MOFs have always been hotspots and challenges for research. Based on the characterization of the C-Cl bond on the triazine skeleton being easily substituted by some functional groups, we designed and synthesized a series of triazine tetratopic carboxylic Cu(II) and Zn(II) MOFs via the reaction of Cu(NO3)2·2.5H2O and ZnSO4·7H2O, as well as triazine tetratopic carboxylic H4TDBA-Cl (H4TBDA-Cl = 5,5'-((6-chloro-1,3,5-triazine-2,4-diyl)bis(azanediyl))diisophthalic acid) under hydrothermal conditions. During the process of synthesizing, the C-Cl bond on the triazine skeleton of the ligand was substituted with different groups, which formed the complexes ([Cu2(TBDA-Cl)(H2O)·10DMF·30H2O]n) (DMF = N,N-dimethylformamide) (1), N(Me)2 -[(CH3)2NH2]4·[Zn3(HTBDA-N)2(SO4)2]n (2) and H ([Cu2(TBDA-H)(H2O)]n) (3), respectively. It is worth noting that the in situ substitution reaction occurred for complexes 2 and 3 during the process of synthesis. Also, the structural analysis showed that the molecules in complexes 1-3 were connected with different building blocks to form different three-dimensional structures. We performed iodine adsorption experiments on the three complexes and found that there was a significant relationship between the structural configuration and adsorption behaviour. The results showed that the complex 1 with the Cl atom on the triazine skeleton could have a boosting effect on adsorption with iodine. It displayed a remarkable adsorption effect for iodine (in the solution of water: 7.6 g g-1 and in the solution of cyclohexane: 548.2 mg g-1). In addition, it also displayed the adsorption effect for JGB dye (204.9 mg g-1). For complex 2, it displayed an uptake effect for iodine in the solution of cyclohexane (529 mg g-1). The possible adsorption mechanism was also investigated. By comparison, we found that chlorine atoms could play an important role in the adsorption processes. The adsorption capacity of complex 1 (containing the chlorine atom in the structure) was much higher than that for complex 3.