Search

The composite anion-exchange material MOR-1-HA (metal-organic resin-1-alginic acid) was investigated as sorbent for the capture of the methyl orange anion (MO - ) from aqueous solutions. MOR-1-HA shows a remarkably high sorption capacity (up to 859 mg g -1 ) and rapid sorption kinetics, the fastest among the reported metal-organic sorbents. It is capable of absorbing MO - over a wide pH range (1-8) and, in addition, it exhibits significant MO - sorption affinity even in the presence of large excesses of competing anions (e.g., Cl - , NO 3 - , SO 4 2- ). The exceptional MO - -sorption properties of MOR-1-HA arise not only from its highly porous structure and easily exchangeable Cl - anions, but also from a multitude of interaction effects, such as electrostatic interactions between MO - and the NH 3 + groups of the material, hydration/dehydration, hydrophobicity/hydrophilicity, size and capacity of generating lateral interactions, and intercalation as revealed by theoretical studies. An ion-exchange column with a stationary phase containing MOR-1-HA and silica sand showed high efficiency for the removal of MO - from various types of aqueous samples. The column can be readily regenerated and reused for many runs with minimal loss (2.3-9.3 %) of its exchange capacity. The simplicity of the MOR-1-HA/sand column and its high regeneration capability and reusability make it particularly attractive for application in the remediation of MO - -contaminated industrial wastewater., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The development of efficient sensors for the determination of the water content in organic solvents is highly desirable for a number of chemical industries. Presented herein is a Mg(2+) metal-organic framework (MOF), which exhibits the remarkable capability to rapidly detect traces of water (0.05-5 % v/v) in various organic solvents through an unusual turn-on luminescence sensing mechanism. The extraordinary sensitivity and fast response of this MOF for water, and its reusability make it one of the most powerful water sensors known., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Extraordinarily effective heavy metal ion scavenger: We show here that the material K(2x)Mn(x)Sn(3-x)S(6) (x = 0.5-0.95) (KMS-1) overcomes the limitations of the known heavy metal ion sorbents, showing the capability to rapidly reduce the concentrations of Cd, Hg, and Pb ions well-below the legally acceptable levels for drinking water. KMS-1 is inexpensive, easily prepared in large quantities, and may play a role in addressing the global problem of water contamination with heavy metal ions. The paradigm of heavy metal ion absorption of KMS-1 is the ability to form very strong M-S bonds.

The hydrothermal synthesis of the purely inorganic open-framework indium selenide (NH(4))(4)In(12)Se(20) (1) is reported. Compound 1 exhibits a unique three-dimensional open-framework structure. The framework of 1 shows an unusual, for a chalcogenide compound, rigidity arising from the unprecedented connection mode of its building blocks. Compound 1 possesses ion exchange capacity for Cs(+), Rb(+), NH(4) (+), but it has selectivity against Na(+) and Li(+). It also showed exceptional stability in relatively concentrated hydrochloric acid. Ion exchange of 1 with hydrochloric water solutions can produce its solid acid analogue H(2)(NH(4))(2)In(12)Se(20). The maximum cation-exchange capacity of 1 was found equal to two equivalents per mol, which is consistent with an exchange mechanism taking place in the 1D-channels formed by the largest cavities. In addition, 1 can do ion-exchange with heavy-metal ions like Hg(2+), Pb(2+), and Ag(+). The capacity of 1 to clean water solutions from heavy-metal ions was preliminarily investigated and found very high. Specifically, 1 can remove 99.9 % of Hg(2+), 99.8 % of Ag(+), and 94.9 % of Pb(2+) from aqueous solutions of each of these ions. Using different synthetic conditions, we isolated compound (NH(4))(2)In(12)Se(19) (2), which also has as good an acid stability as 1, but no ion-exchange properties. Overall, this work provides new hydrothermal synthetic approaches for isolation of all-inorganic open-framework chalcogenides.

Reaction of [V(VI)OCl(2)(thf)(2)] with a bidentate nitrogen-donor ligand (L: phen=1,10-phenanthroline, 5-mephen=5-methyl-1,10-phenanthroline, bipy=2,2'-bipyridine, 5,5'-me(2)bipy=5,5'-dimethyl-2,2'-bipy) in methyl alcohol, in the presence of triethylamine, leads to the formation of hexameric [V(2) (IV)V(4) (V)] oxo-alkoxo-vanadates of the general formula [V(6)O(12)(mu(2)-OCH(3))(4)(L)(4)].x H(2)O [L=phen (1.4 H(2)O), 5-mephen (2.6 H(2)O), bipy (3.4 H(2)O), 5,5'-me(2)bipy (4.H(2)O)]. X-ray structure analysis of 1.2 H(2)O and 4.8 CH(3)OH revealed a pair of V(3)O(13)N(4) trimeric units sharing two corners, with a centrosymmetric planar V(6)-core. In addition, a fully oxidized V(V) species [V(V) (4)O(8)(OCH(3))(2)(mu(3)-OCH(3))(2)(5,5'-me(2)bipy)(2)].3 CH(3)OH (5.3 CH(3)OH) was isolated from the reaction mixture used for the synthesis of 4.H(2)O. The crystal structure of 5.3 CH(3)OH revealed a dicubane-like framework with two missing vertices. Electron paramagnetic resonance (EPR) and variable temperature magnetic susceptibility studies for the hexamers 1.4 H(2)O and 3.4 H(2)O showed the complete localization of the single 3d electrons on the V(IV) ions and unusual ferromagnetic interaction between the two paramagnetic vanadium(IV) ions separated by a distance of about 5.1 A. Furthermore, intermolecular antiferromagnetic interactions through pi-contacts of phenyl rings were observed for these species below 8 K. The ferromagnetic exchange coupling observed in the hexanuclear compounds 1.4 H(2)O and 3.4 H(2)O is also discussed using ab initio UHF calculations on a model compound. The value of the exchange coupling constant (3.7 cm(-1)) for this model compound, calculated using the broken symmetry approach, is in good agreement, both in sign and magnitude, with the experimental J values (6.00 cm(-1) for 1.4 H(2)O and 8.54 cm(-1) for 3.4 H(2)O).