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In this work, five novel Cd/Zn-based MOFs with different topological framework, namely {[Cd(bimb)(Hbipa)]·H 2 O} n (1), {[Cd 3 (dimb) 3 (bipa) 2 (H 2 O) 2 ·2H 2 O} n (2) , [Cd(bimd)(Hbipa)(H 2 O)] n (3) , {[Zn(bipd)(Hbipa)]·H 2 O} n (4) and [Zn(bimb)(Hbipa)] n (5) had been synthesized and characterized. Worth noting, Complex 1 and 2 had effective separation behaviors towards MO and MBE dyes respectively, which could reach the adsorption equilibrium within a quite short time even if there existed another kind of dye in the system. Meanwhile, Complex 3 – 5 showed great performance in CR adsorption. Additionally, Complex 3 – 5 also showed excellent photocatalytic degradation capabilities toward MB and MV dyes under UV irradiation. According to the study, these five metal-organic frameworks can be used as a kind of functional materials in the adsorption and photocatalytic degradation of organic dyes in wastewater. [Display omitted] • Produce novel Cd/Zn -based MOFs that possess novel 3D structure. • Selectively absorb specific aromatic dyes in a mixed aqueous system. • Exhibit efficient photocatalytic degradation abilities towards MB/MV in aqueous solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Produce two novel Zn-based MOFs under solvothermal conditions. • Both of Zn-based MOFs possess analogous layered stacked structure. • Selectively absorb specific aromatic dyes in a mixed aqueous system. • Exhibit efficient photocatalytic degradation abilities towards MB/MV in aqueous solution. Two novel Zn-MOFs constructed from 5-hydroxy-2-nitroisophthalic acid (H 2 DIPA) and 5-(4-carboxy-2-nitrophenoxy)-2-nitroisophthalic acid (H 3 BPPA), namely: {[Zn 2 (DIPA) 2 (bimp) 5 ]·DMF·2H 2 O} n (Zn-MOF 1), {[Zn 2 (HBPPA) 2 (bibp) 2 ]·2H 2 O} n (Zn-MOF 2) (bimp = 1,4-di(1H-imidazol-1-yl)butane, bibp = 4,4′-bis(imidazolyl) biphenyl), have been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TG). The single-crystal X-ray diffraction analysis indicates that Zn-MOF 1 exhibits an uncommon 3-nodal framework with a (4·6·8)(4·63·82)(66) topology, whereas Zn-MOF 1 exhibits an uninodal 4-connected framework with a (44·62) topology. Moreover, both of the two Zn-MOFs exhibit exceptional dye adsorption capacities towards the organic dyes with high adsorption rates and excellent adsorption amounts. Particularly, Zn-MOF 1 can selectively adsorb the cationic dye malachite green (MG) whereas Zn-MOF 2 adsorb the anionic dye methyl orange (MO) when there exists another kind of dye in the system. The adsorption process can be illustrated by pseudo-second order kinetic and Langmuir isotherm, and the feasible adsorption mechanism could be the electrostatical interactions, hydrogen bonding between the MOFs and the dyes. Meanwhile, the two Zn-MOFs also show good photocatalytic degradation capabilities toward MB/MV dyes under UV irradiation, and the mechanism studies demonstrate that the main active species are ·OH radicals. Therefore, this functional MOF materials can be treated as a convenient and cost-efficient solution for the sewage handling and environmental protection. [ABSTRACT FROM AUTHOR]