MOFs-based Fe@YAU-101/GCE electrochemical sensor platform for highly selective detecting trace multiplex heavy metal ions.

The construction of sensors with specific recognition functions can easily, sensitively and efficiently detect heavy metal ions, which is a demand in the field of electrochemical sensing and an important topic in the detection of environmental pollutants. An electrochemical sensor based on MOFs composites was developed for sensing of multiplex metal ions. The large surface area, adjustable porosities and channels in MOFs facilitate successful loading of sufficient quantities highly active units. The active units and pore structures of MOFs are regulated and synergetic with each other to enhance the electrochemical activity of MOFs composites. Thus, the selectivity, sensitivity and reproducibility of MOFs composites have been improved. Fortunately, after characterization, Fe@YAU-101/GCE sensor with strong signal was successfully constructed. In the presence of target metal ions in solution, the Fe@YAU-101/GCE can efficiently and synchronously identify Hg2+, Pb2+, and Cd2+. The detection limits (LOD) are 6.67 × 10-10 M(Cd2+), 3.33 × 10-10 M(Pb2+) and 1.33 × 10-8 M (Hg2+), and are superior to the permissible limits set by the National Environmental Protection Agency. The electrochemical sensor is simple without sophisticated instrumentation and testing processes, hence promising for practical applications.

Highly selective detecting Aspartic acid, detecting Ornidazole and information encryption and decryption supported by a heterometallic anionic Cd (II)-K (I)-MOF.

A highly stable heterometallic MOF, {[(Me2NH2)2]·[Cd2K2(L)2(H2O)]}n (H4L = terphenyl-2, 2', 4, 4'-tetracarboxylic acid) (1), was synthesized. 1 featuring one-dimensional channels can efficiently detect Aspartic acid with a low limit of detection (LOD) value (2.5 µM). More interestingly, 1 can encapsulate Eu3+ and sensitize the visible-emitting characteristic fluorescence of Eu3+ in aqueous solution. Then, Eu3+@CdK-MOF is found to be an excellent fluorescence sensor for the detection of Ornidazole (ODZ) and the portable ODZ test paper is also successfully designed. Eu3+@CdK-MOF can also be used as fluorescent ink to write some words. The words can be hidden when treated with acid vapor and then the words can be restored when treated with alkaline vapor. More importantly, the hidden information can be read repeatedly. Therefore, this reversible light-emitting and reusable property have great potential for development in information encryption and decryption and information storage.

Information encryption, highly sensitive detection of nitrobenzene, tetracycline based on a stable luminescent Cd-MOF.

A stable luminescent Cd-MOF, formulated as [Cd(L)0.5(4, 4'-bpy)0.5]·H2O (1), (H4L = 1, 1'-ethylbiphenyl -3, 3', 5, 5'- tetracarboxylic acid, 4, 4' -bpy = 4, 4'-bipyridine), is acquired under solvothermal conditions. 1 exhibits stability in the pH range from 1.5 to 12.2 and in different organic solvents. 1 can detect tetracycline and nitrobenzene by fluorescence quenching with high sensitivity and selectivity. The detection limits are 0.14 µM and 14 nM, respectively. Interestingly, 1 can encapsulate Tb3+ and sensitize its characteristic peaks. Moreover, the fluorescent ink is prepared by using the luminescent properties of the Tb3+@Cd-MOF. The light of the fluorescent ink disappears in an acid gas HCl atmosphere and then reappears in an alkaline gas ammonia atmosphere. This phenomenon can be repeated and the reason for this phenomenon is also explained in the article. Therefore, Tb3+@Cd-MOF has huge application potential in information encryption.

Design of High-Symmetrical Magnesium-Organic Frameworks with Acetate as Modulator and Their Fluorescence Sensing Performance.

During the formation of magnesium-organic frameworks, the coordination sphere of magnesium tends to be partially occupied by O-containing solvent molecules such as amides, which will dramatically decrease the symmetry of Mg-organic frameworks and thus lead to low stability. It is noted that up to now, most reported Mg-metal-organic frameworks (MOFs) (>80%) crystallize in the space groups whose symmetry is lower than that of a tetragonal system. In this work, we demonstrate that acetate (Ac) may act as modulator to eliminate the influence of amide solvent and improve the symmetry of Mg-organic frameworks. Two novel Mg-MOFs, namely, {[(CH3)NH3]4[Mg3(BTB)8/3(Ac)2(H2O)]} n (SNNU-35, H3BTB = 4',4'',4'''-benzene-1,3,5-tribenzoic acid) and {[(CH3)2NH2][Mg2(FDA)2(Ac)]} n (SNNU-36, H2FDA = 2,5-furandicarboxylic acid) were successfully designed, which crystallize in rhombohedral R-3 and tetragonal I4 /mmm space groups, respectively. Four independent BTB ligands link three unique Mg cations and generate superlarge [Mg21BTB17] nanocages, which interlock each other by strong π···π stacking to give a two-fold interpenetrating architecture of SNNU-35. On the other hand, carboxylate and acetate groups chelate Mg atoms to form one-dimensional chains, which are extended by FDA to produce the rod-packing framework of SNNU-36. Two microporous Mg-MOFs both exhibit notable CO2 and H2 uptakes. H3BTB and H2FDA ligands both have emission features, and Mg ions usually can enhance the fluorescent intensity, which lead to a strong solid-state luminescence emission property of SNNU-35 and -36. Importantly, two Mg-MOFs both show fast and quantative sensing performance for nitrocompounds. Among three selected models of substrate, SNNU-35 and -36 can eliminate the interference of nitromethane (NM) and exhibit high sensitivity to nitrobenzene (NB) and o-nitrotoluene (2-NT) with large k sv values (>105 M-1). Especially, the fluorescence quenching efficiency of NB (5000 ppm) and 2-NT (8000 ppm) can reach 96.3% and 89.5% and 85.0% and 83.7% for SNNU-35 and -36, respectively. This work offers not only an effective route to improve the symmetry of magnesium-organic frameworks but also two potential fluorescence sensors for nitroaromatic compounds.

A novel 3D Cd(ii) coordination polymer generated via in situ ligand synthesis involving C-O ester bond formation.

A novel 3D Cd(ii) coordination polymer {[Cd(ddpa)(2,2'-bpy)]·H2O} n (1) (H2ddpa = 5,10-dioxo-5,10-dihydro-4,9-dioxapyrene-2,7-dicarboxylic acid, 2,2'-bpy = 2,2'-bipyridine) is hydrothermally synthesized in situ, and the influencing factors and mechanism for the in situ reaction are briefly discussed. The synthesis of 1 requires the formation of a new C-O ester bond. This current study confirms that metal ions and N-donor ligands play important roles in the domination of the in situ ligand from 6,6'-dinitro-2,2',4,4'-biphenyltetracarboxylic acid (H4dbta). Furthermore, the structure, thermal stability and photoluminescent property of 1 are also investigated.

[Effects of mowing and grazing on soil nutrients and soil microbes in rhizosphere and bulk soil of Stipa grandis in a typical steppe].

This study conducted experiments using Stipa grandis, the dominant species of the typical steppe in Inner Mongolia. The research explored the different effects of mowing and grazing on organic carbon, total nitrogen, available nitrogen, total phosphorus and available phosphorus in rhizosphere and bulk soil. The results showed that: Both mowing and grazing inhibited assemble and storage capacity of rhizosphere, and decreased the organic carbon, total nitrogen, and available nitrogen contents in rhizosphere soil. The rhizosphere effect on total phosphorus in soil was found to be insignificant because of its high immobility. Available phosphorus in soil was distributed heterogeneously. Available soil phosphorus under mowing and grazing changed but the difference was not significant between rhizosphere and bulk soil. Grazing drastically reduced the number of soil microbes. The availability of soil nutrients was significantly correlated with soil microbial numbers. The status of soil nutrients could be more closely aligned with the change in bacteria and fungi. Grazing brought about greater soil nutrient loss and soil microbe loss than did mowing.

catena-Poly[[(1,10-phenanthroline)cobalt]-µ-2,4'-oxydibenzoato].

In the title compound, [Co(C(14)H(8)O(5))(C(12)H(8)N(2))](n), the Co(II) atom is six-coordinated in a distorted octa-hedral coordination geometry by four O atoms from two chelating carboxyl-ate groups from different 2,4'-oxydibenzoate anions and by two N atoms from a 1,10-phenanthroline (phen) ligand. The two benzene rings of the 2,4'-oxydibenzoate ligand form a dihedral angle of 77.14 (16)°. Adjacent Co(II) atoms are bridged by 2,4'-oxydibenzoate anions to form a helical chain that propagates along the b-axis direction. Neighboring chains are further assembled by inter-molecular π-π stacking inter-actions between inversion-related phen ligands [centroid-to-centroid distance = 4.0869 (8) Å] to form a two-dimensional supra-molecular architecture.

catena-Poly[zinc(II)-bis-[µ(2)-3-(3-pyrid-yl)-benzoato]-κO:N;κN:O].

In the title compound, [Zn(C(12)H(8)NO(2))(2)](n), the Zn(2+) cation is coordinated by a pair of carboxyl-ate O atoms as well as two pyridyl N atoms to afford a distorted tetra-hedral environment. Adjacent Zn(2+) cations, with a separation of 8.807 (2) Å, are linked by two 3-(3-pyrid-yl)benzoate ligand bridges, generating an infinite ribbon extending parallel to [001].

[Perceptions and adaptation strategies of herders in desert steppe of Inner Mongolia to climate change].

Desert steppe is very vulnerable to climate change. The herders caring for their livestock in such a natural environment have to face the challenges of rapid climate change. In this paper, a household-level questionnaire was conducted in the Suniteyou District of Inner Mongolia, China, aimed to analyze the herders' perceptions and adaptation strategies to climate change, extreme climate events in particular. In this Steppe where precipitation is rare and meteorological disasters are frequent, drought is the main extreme climate event with the broadest affecting area, the highest affecting degree, and the greatest frequency. The sensitivity of the herders to drought is far higher than that to other extreme climate events, and also, the perceptions to drought induce the herders having deep perceptions to the extreme climate events such as strong wing, dust storm, and heavy snow. Relative to the perceptions to long-term climate change, the perceptions to short-term climate change are more deep and precise. The herders can estimate the long-term climate change trend according to their perceptions to the latest 10 years climate change. They attribute the poor livestock health and the reduced forage yield greatly to climate change. Yet, the herders are inexperienced in implementing efficient adaptation strategies. Generally, their adaptation measures are quite simplex and rather passive.

1,3-Di-4-pyridylpropane-4,4'-oxy-dibenzoic acid (1/1).

In the title compound, C(13)H(14)N(2)·C(14)H(10)O(5), a 1:1 cocrystal of 1,3-di-4-pyridylpropane (bpp) and 4,4'-oxydibenzoic acid (H(2)oba), the dihedral angle between the two benzene rings of the flexible H(2)oba mol-ecule is 57.07 (1)°; the two pyridine rings of bpp make a dihedral angle of 27.52 (1)°. Strong inter-molecular O-H⋯N hydrogen bonds link the mol-ecules into chains, which are then linked into a three-dimensional network through inter-molecular C-H⋯O and π-π stacking inter-actions [centroid-centroid distance = 3.7838 (3) Å].