Search

Owing to their highly predictable porous structures, facile synthesis, and the presence of functional open metal sites, metal–organic frameworks (MOFs) are extensively employed in various fields, including energy storage, catalysis, adsorption, and separation. Nevertheless, the limited hydrolytic stability exhibited by numerous MOFs poses a significant challenge to their practical application. In the present study, we present the synthesis and characterization of a uranyl organic framework (TCPP‐U1) with a highly porous structure, which is constructed by assembling cobalt, uranyl, and the porphyrin ligand 5,10,15,20‐tetra(4‐carboxyphenyl)porphyrin (TCPP). However, TCPP‐U1 demonstrates poor hydrolytic stability when exposed to water (the structure can be destroyed even after 2 min of exposure to water), greatly impeding its potential applications that would benefit from its high surface area. To address this limitation, we developed a hybrid composite by incorporating acid‐treated multi‐walled carbon nanotubes (CNTs) into the TCPP‐U1 framework via a solvothermal method designated as CNTs@TCPP‐U1. Remarkably, the obtained CNTs@TCPP‐U1 composite possesses an identical crystal structure and morphology to the original TCPP‐U1 yet exhibits significant enhancements in hydrolytic stability (the structure remains stable even after 3 days of immersion in water). Furthermore, CNTs@TCPP‐U1 demonstrates a significant photocatalytic effect on the degradation of tetracycline hydrochloride in aqueous solutions. The reaction rate constant (k) for the pseudo‐first‐order kinetic model is 0.0059 min−1. Our findings present a novel perspective for enhancing the stability and expanding the performance of MOFs materials. [ABSTRACT FROM AUTHOR]

Uranium phosphonates, an important class of actinide-organic coordination polymers, exhibit an exceptionally diverse and broad range of crystal structures. A variety of structure topologies have been identified for hexavalent uranium phosphonates, including cage clusters, chains, ribbons and tubes, sheets, and three-dimensional frameworks. In contrast, only a handful of tetravalent uranium phosphonates are known. This review presents a comprehensive account of the crystal structures of uranium phosphonates and the various building units ( e.g. discrete monomers, polymeric units, infinite chains, and sheets) that result from the numerous coordination modes of phosphonate ligands with uranium. [ABSTRACT FROM AUTHOR]

Reaction of uranyl dications with (2-carboxyethyl)(phenyl)phosphinic acid (CPPA, H2L) under hydrothermal conditions gave two layered isomers (UO2)2(L)2, namely, CPP-U1 and CPP-U2. Both of them feature edge-sharing uranyl dimers as structure-building units, which are ligated by CPP ligands in different ways, thus leading different layered arrangements. With the addition of imidazole derivatives, two three-dimensional structures UO2(L)(dib)0.5 (CPP-U3) and UO2(L)(bbi)0.5 (CPP-U4) were generated, in which the similar uranyl-phosphinate layers are connected by two different imidazole derivatives by means of the U-N connection [dib = 1,4-di(1 H-imidazol-1-yl)benzene; bbi = 1,1′-(1,4-butanediyl)bis(imidazole)]. The syntheses, structure, as well as the IR spectra, and luminescent and photocatalytic properties of these uranyl organophosphinates are reported in this paper. [ABSTRACT FROM AUTHOR]

Five novel zinc uranyldiphosphonates have been hydrothermallysynthesized by using a series of flexible diphosphonate ligands, includingethane-1,2-diyldiphosphonic acid (H4EDP), propane-1,3-diyldiphosphonicacid (H4PDP), and butane-1,4-diyldiphosphonic acid (H4BDP). Compound Zn(H2tib)(UO2)2(EDP)(HEDP)(H2EDP)0.5·3H2O(EDP-ZnU1, tib = 1,3,5-tri(1H-imidazol-1-yl)benzene)comprises dimeric U2O12unit condensed by twoUO7pentagonal bipyramids, which are further connectedby Zn-centered polyhedra and EDP ligands resulting in a 3-dimensionalframework. Compound [Zn(bipy)(H2O)](UO2)(PDP)(PDP-ZnU1, bipy = 2,2′-bipyridine) also featuresU2O12dimers and Zn-centered polyhedra, buta layered arrangement is formed. Different from that in PDP-ZnU1, the uranium exists in the form of UO6tetragonal bipyramidand is surrounded by four PDP ligands to generate the layered structureof Zn(bipy)(UO2)(PDP) (PDP-ZnU2). ZnO2N2tetrahedra are connected on both sides of thelayers. Both Zn2(phen)4(UO2)3(BDP)(HBDP)2·4H2O (BDP-ZnU1, phen = 1,10-phenanthroline) and Zn2(bipy)2(UO2)3(HBDP)2(H2BDP)2(BDP-ZnU2) contain U2O12dimers and UO6tetragonal bipyramids. In BDP-ZnU1, uranyl centers are bridged by BDP to form a 2-dimensional structure,on which Zn(phen)2are decorated. Whereas in BDP-ZnU2, uranyl phosphonate layers are connected by bridging ZnO3N2to produce framework structure. All of these compoundshave been investigated by IR and photoluminescent spectroscopy. Theircharacteristic green light emissions have been attributed to transitionproperties of uranyl dications. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of hexa[4-(carboxyphenyl)oxamethyl]-3-oxapentane (H6L) with rigid coligands, 2,2′-bipyridine (bipy), 1,4-bis-(1-imidazolyl)benzene (dib), and 4,4′-bis(1-imidazolyl)biphenyl (bibp) in the presence of manganese salts produce four porous Mn(ii) metal–organic frameworks (Mn–MOFs), namely, Mn3(L)(bipy)2 (1), Mn3(L)(dib) (2), Mn3(L)(dib)(H2O)2 (3), and Mn6(L)2(bibp)1.5(H2O)54. Single crystal X-ray diffraction analyses reveal that 1–4 consist of trinuclear MnII subunits, which are further connected into four interesting nets, 4,4-connected pts net for 1, 4,6-connected fsc net for 2, and two novel nets for 3 and 4, by the synergistic effect of carboxylate groups and functionally complementary N-donor ligands. They exhibit high potential solvent accessible volumes of 35.0%, 33.5%, 45.1%, and 56.5% for 1–4, respectively. Magnetic studies indicate the presence of weak antiferromagnetic interactions between MnII centers in these compounds. [ABSTRACT FROM AUTHOR]

Solvothermal assembly of Co(II) ion, a semirigid tetrahedralcarboxylateligand tetrakis[(4-carboxyphenyl)oxamethyl]methane acid (H4L), and rigid linear bidentate linker 1,4-di(1H-imidazol-1-yl)benzene(dib) or 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl(dibp) yields four novel metal–organic frameworks (1–4) with different topological connections. [Co2(L)(dib)]·3DMF (1) is a 2-fold interpenetrating sqc422 network and contains 3-dimensional interconnectedchannels along [100], [010], and [110] directions; [Co4(L)2(dib)3(H2O)4]·4H2O (2) is a three-dimensional 3,4,4-connectednew topology with 5-fold interpenetration; [Co2(L)(dibp)]·5DMF(3) and Co2(L)(dibp)2(4) are formed in the presence of dibp linker; they feature three-dimensionalnovel topologies based on 4,6-connection and 4,4-connection, respectively,and no interpenetration is observed. It is demonstrated that interpenetrationis accessible simply by changing auxiliary ligands and solvents. Magneticstudies reveal that complexes 1and 3exhibitantiferromagnetic behavior. [ABSTRACT FROM AUTHOR]

A series of novel ternary Ln–Ru–W hybrids constructed by metalloligands ([RuII(bpy)2(4,4′-dcbpy)](PF6)2, m-H2LRu) and high-nuclear lanthanide clusters have been successfully synthesized using an efficient “metalloligand” strategy for the first time. Slow magnetic relaxation has been observed within the Dy-based hybrid. [ABSTRACT FROM AUTHOR]

Through assembly of two metal ions (Li + and Zn 2+ ) and a quadridentate carboxylate ligand H 4 L1 (5-(bis(4-carboxybenzyl)amino)isophthalic acid), a new metal-organic framework ( HNU-22 , HNU is the abbreviation of Hainan University) was successfully constructed with the formula of ZnLi 2 (L1)(DMF)(H 2 O) (DMF = N , N ′-dimethylformamide). It should be noted that Li + and Zn 2+ are both involved in coordination, four Li + and two Zn 2+ , are connected together through the O atoms of the carboxylate ligand, forming the heteronuclear Li 4 Zn 2 cluster, which has never been reported in the literature. It is a rod-shaped metal cluster, and the linkage mode is Li-Zn-Li 2 -Zn-Li. When the metal clusters and organic ligands are simplified, HNU-22 can be regarded as a 4,8-connected topology with the flu symbol. Furthermore, HNU-22 shows luminescence sensing property toward Fe 3+ . [ABSTRACT FROM AUTHOR]