Two metal–organic frameworks Zn2(Tipa)2(OH)·3NO3·12H2O (FIR-53, FIR denotes Fujian Institute of Research, Tipa = tris(4-(1H-imidazol-1-yl)phenyl)amine)) and Zn(Tipa)·2NO3·DMF·4H2O) (FIR-54) ...with large nanotubular channels were synthesized via Zn(II) ions coordinate the neutral Tipa ligand. The framework of FIR-53 contains 1D channels along the c axis with a cross section of 18 × 13 Å2. FIR-54 also consists of large channels with the 10.5 × 10.5 Å2 open windows. These porous materials efficiently trap Cr2O7 2– inorganic pollutant ions via the single-crystal-to-single-crystal (SC-SC) approach. The Cr2O7 2– uptake capacities of FIR-53 and FIR-54 are high to 74.2 and 103 mg/g, respectively. Furthermore, the Cr2O7 2– trapping–releasing process of FIR-53 displays good regeneration. Meaningfully, the structure of FIR-53 after ion exchange can be accurately obtained by single-crystal X-ray diffraction, which further elaborates the SC-SC transformation.
Homochiral metal–organic frameworks (HMOFs) are efficient materials for enantioselective adsorption. However, the combination of size selectivity and enantioselectivity is still a major challenge in ...the field of HMOFs. Herein, two enantiomorphic HMOFs built from predesigned proline‐derived ligands are presented. Both of them show multiple homochiral features: they contain four different helical chains and three types of helical channels. Due to the size effect of the helical channels, each HMOF can enantioselectively adsorb methyl lactate with high ee. The results reveal a new approach toward size‐dependent enantioselective separation of racemic compounds by using HMOFs built from inexpensive proline derivatives.
Multiply homochiral: Two enantiomorphic homochiral metal–organic frameworks (HMOFs) built from predesigned proline derivatives show multiple homochiral features: they contain four different helical chains and three types of helical channels. Due to the size effect of the helical channels, each HMOF can enantioselectively adsorb methyl lactate with high ee values (see figure).
Under hydrothermal condition, lactate derivative (R)‐4‐(1‐ carboxyethoxy)‐2‐methylbenzoic acid ((R)‐H2cma) as chiral synthon assembled with 4,4′‐di(1H‐imidazol‐1‐yl)‐1,1′‐biphenyl (4,4’‐dib) and ...Ni(II) ions to obtain complex {Ni2((R)‐cma)2(4,4’‐dib)2(H2O) ⋅ 2H2O}n (HU20‐R). In complex HU20‐R, carboxyl group from lactate unit of (R)‐cma2− anion and coordinating H2O molecule adopt a μ2‐coordination mode to obtain dinuclear Ni2(CO2)2(H2O)2+ cluster. (R)‐cma2− anions and Ni(II) ions build single left‐handed (R)‐cma‐Ni‐chain, while 4,4’‐dib ligands are bridged by different Ni(II) centers to form double left‐handed 4,4’‐dib‐Ni‐chain. These helical secondary structures are further connected together to result in an 8‐connected 3D framework. PXRD tests indicated that complex HU20‐R has well hydro‐stability. UV‐vis absorption experiment confirmed that HU20‐R is a semi‐conducting material with strong absorption capacity for ultraviolet‐visible (UV‐vis) light. Additionally, electrochemical experiment revealed that HU20‐R has low impedance and high charge transport capacity. Further test results confirm that HU20‐R has noticeable photo‐catalytic effect in photodegradation of Rhodamine B (RhB) and antiferromagnetic property.
Using lactic acid derivatives as chiral ligands, a pair of unprecedented homochiral metal–organic zeolites have been synthesized that feature zeotype CAN topology and have high porosity for ...enantioselective separation of racemates.
A pair of new chiral Co(II) metal‐organic frameworks based on semi‐rigid lactic acid derivatives, namely, {Co((R)‐CBA)(1,3‐DPP)(H2O)0.5 ⋅ H2O}n(1‐R) and {Co((R)‐CBA)(1,3‐DPP)(H2O)0.5 ⋅ H2O}n (1‐S) ...(H2CBA=4‐(1‐carboxyethoxy) benzoic acid, 1,3‐DPP=1,3‐di(pyridin‐4‐yl)propane) were synthesized under hydrothermal conditions. The structures of complexes 1‐R and 1‐S were determined by single crystal X‐ray crystallography, revealing dinuclear cobalt units are connected through (R)‐ or (S)‐CBA2− anions that lead to the formation of enantiomeric helical chains. Helical chains are further linked together to build 3D Co‐(R)‐CBA (Co‐(S)‐CBA) framework in 1‐R(1‐S). Furthermore, more large helical chains are formed by Co(II) centers and 1,3‐DPP ligands in 1‐R and 1‐S. As a result, 1,3‐DPP ligands are introduced into complexes to stabilize the CBA−Co frameworks to obtain a four‐connected dia net. Apart from delicate structure, the UV‐vis sorption spectrum, Mott‐Schottky measurements and electrochemical impedance spectroscopy (EIS) demonstrated that complex 1‐R is a typical n‐type semiconductor with low resistance in charge transportation. Photo‐catalytic test result confirmed the complex 1‐R has catalytic activity for the degradation of RhB.
Two 3D complexes with tetranuclear clusters Co4(CO2)8(μ2-H2O)2 and Co4(μ3-OH)26+ were obtain under hydrothermal conditions, as n-type semiconductors, which have catalytic activity for the degradation ...of Rhodamine B.
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Complexes {Co2(DTA)2(1,4-BMIB)(H2O)·1·.5H2O}n(ZNC-9) and {Co2 (DTA)1.5(OH)(TIB)·5H2O}n (ZNC-10) (H2DTA = 2,5-dimethoxyterephthalic acid, 1,4-BMIB = 1,4-bis(2-methyl-1H-imidazol-1-yl)benzene, TIB = 1,3,5-tri(1H- imidazol-1-yl)benzene) were obtained via hydrothermal reaction condition. DTA2− ligands adopted various coordination modes to result in tetranuclear clusters Co4(CO2)8(μ2-H2O)2 and Co4(μ3-OH)26+ in ZNC-9 and ZNC-10, respectively. In complex ZNC-9, Co4(CO2)8(μ2-H2O)2 as 10-connected node was bridged by DTA2− and 1,4-BMIB to form a 3D framework with Schlafli symbol of (36.434.62). In complex ZNC-10, DTA2− ligands and Co4(μ3-OH)22+ built a 4-connected dia net, while TIB and Co4(μ3-OH)2 units built a 3,6-connected ant net. The dia and ant nets further constructed a (3,10)-connected framework with point symbol (3.42)2(34.410.512.613.76). Additionally, UV–vis spectra and electrochemical tests have confirmed that ZNC-9 and ZNC-10 belong to n-type semiconductors possessing low resistance for charge transportation. In photo-catalytic experiments, ZNC-9 and ZNC-10 have obvious catalytic activity in degradation of dye under ultraviolet light.
Utilizing (R)-H3CIA as a chiral template, an unprecedented homochiral metal-organic framework (MOF) with zeotype GIS topology is obtained from achiral 1.4-DIB ligands and Zn(II) ions, which opens up ...a feasible approach to create zeolitic MOFs with homochirality.
Chiral coordination polymers Ni((R)-ceba) (1,3-dpp) (H2O)0.5 (HU15-R), Ni((R)-ceba) (1,3-dpp) (H2O)0.5 (HU15–S), Ni((R)-ceba) (4,4′-dib) (H2O)0.5 (HU16-R) and Ni((S)-ceba) (4,4′-dib) (H2O)0.5(HU16–S) ...were prepared from lactate-derived synthons and different N-donor linkers under hydrothermal conditions (H2ceba = 4-(1-carboxyethoxy)benzoic acid, 1,3-dpp = 1,3-di(pyridine-4-yl)propane, 4,4′-dib = 4,4′-di (1H-imidazole-1-yl)-1,1′-biphenyl). Structural analysis confirmed that that all complexes are three-dimensional frameworks containing dinuclear Ni2(CO2)2(H2O)2+ clusters. In addition, four types of helical structures were also obtained though chiral transfer and asymmetric induction from chiral synthons among them. (R)-ceba2- anions and Ni(Ⅱ) ions were bridged together to construct right-handed (R)-ceba-Ni chains in HU15-R and HU16-R, while (S)-ceba2- anions were linked by Ni(Ⅱ) ions to build right-handed (S)-ceba-Ni chains in HU15–S and HU16–S. Apart from chiral synthons, achiral linkers 1,3-dpp and 4,4′-dib assembled with Ni(Ⅱ) ions to form single 1,3-dpp-Ni chains in HU15-R and HU15–S and double 4,4′-dib-Ni chains in HU16-R and HU16–S, respectively. Meanwhile, the introductions of N-donor ligands resulted in varied topological structures. HU15-R and HU15–S are 4-connected dia nets, while HU16-R and HU16–S are 8-connected frameworks. Moreover, magnetic experiments indicated that antiferromagnetic interactions exist in these complexes.
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•Enantiomeric coordination polymers.•Various helixes based on chiral and achiral components.•Chiral transfer and asymmetric induction.
Under solvothermal synthesis, 1,4-bis(4-methyl-1H-imidazole-1- yl)benzene(1,4-BMIB), 1,1'-(2,5-dimethyl-1,4-phenylene)bis(1H-imidazole)(1,1′- DPBI) and 1,3,5-tri(1H-imidazole-1-yl)benzene (1,3,5-TIB) ...were used to combine with 2,5-dimethoxyterephthalic acid (H2DTA) and Cd(Ⅱ) to obtain three luminescent complexes {Cd(DTA)(1,4-BMIB)‧H2O}n(1), {Cd(DTA)(1,1′-DPBI)(H2O) ‧H2O}n(2) and {Cd(DTA)(1,3,5-TIB)‧0.5H2DTA}n (3), respectively. Single-crystal diffraction tests revealed that complex 1 belongs to monoclinic crystal system with C2/c space group, where binuclear Cd2(CO2)4 units act as six-connected metal centers resulting in three-dimensional frame with topological symbol of (48.52.65). Complexes 2 and 3 crystallize in triclinic P-1 space group. Among them, complex 2 is a dia-type triple interspersed framework, while complex 3 is a 2-fold-interpenetrating structure. Comparing to the fluorescent emission spectra of ligands, the fluorescence of complexes is obviously enhanced. In addition, all complexes have good recognition capability for Fe3+ and Cr2O72− ions, and their detection curves fit with Stern-Volme equation (I0/I = 1+KsvM) in low concentration range. The fluorescent intensities from complexes indicate a good linear relationship with the concentration of detection ions, and the detection limit is also low. Through scanning for various ions, these complexes are expected to be fluorescent sensors for identifying Fe3+ and Cr2O72− ions.
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•Three luminescent MOFs.•Various three-dimensional (3D) frameworks.•Good recognition capability for Fe3+ and Cr2O72− ions as fluorescent materials.
