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A series of dimeric oxomolybdenum(V) 2,2′-bipyridine or 1,10-phenanthroline α-hydroxycarboxylates trans-[(MoO)2O(glyc)2(bpy)2]·3H2O (1), trans-[(MoO)2O(lact)2(bpy)2]·3H2O (2), trans-[(MoO)2O(Hmal)2(bpy)2] (3), trans-[(MoO)2O(lact)2(phen)2]·4H2O (4) and trans-[(MoO)2O(Hmal)2(phen)2]·4H2O (5) have been synthesized in acidic media for comparisons, where glycolate, lactate and malate in 1–5 chelate to molybdenum(V) with bidentate α-alkoxy and α-carboxy groups respectively. Unlike the molybdenum(IV) lactate in low valence [1] , no protonation was observed for α-alkoxy groups even under acidic condition. The two molybdenum atoms in 1 and 3 are paramagnetic independently as examples by EPR spectroscopies. Solid state 13C NMR spectra of 1 and 3 show large downfield shifts for the coordinated glycolate and malate (δα-alkoxy 75.4, 82.8 ppm, Δδ 13.4 ppm). Moreover, a monomeric mixed ligand oxomolybdenum(VI) complex MoO2(glyc)(bpy) (6) was isolated.

Insoluble lead(II) ethylenediaminetetraacetate isomers [Pb2(EDTA)(H2O)]2n (1) and [Pb4(EDTA)2]n·2nH2O (2) and allomers Pbn[Pb(EDTA)Pb(H2O)X]2n·2nH2O (X = Cl, 3 and Br, 4) are isolated from the reactions of lead nitrate with ethylenediaminetetraacetic acid in acidic solution (H4EDTA = ethylenediaminetetraacetic acid). The four complexes are fully characterized via elemental analysis, FT-IR spectroscopy, thermogravimetric analyses, solid state 13C NMR spectroscopy and X-ray crystal structure analyses. Topological analyses of complexes 2 and 3(4) show unusual (6,8)-connected 2-nodal and (4,5,6)-connected 3-nodal network topologies, respectively. The insertions of chloride and bromide in 3 and 4, respectively, give new polymeric lead–EDTA complexes. Products 3 and 4, which are obtained at room temperature, show a significant halide-assisted formation effect of insoluble ethylenediaminetetraacetato lead(II) complexes, which is supported by solid state NMR and X-ray crystal structure analyses.

A series of pH dependent water soluble calcium 1,3-propylenediaminetetraacetates [Ca(1,3-H4pdta)(NO3)2(H2O)2]n (1), [Ca(1,3-H2pdta)]n·nH2O (2), K4[Ca2(1,3-pdta)2]·2H2O·2CH3OH (3) and Ca2(H2O)6[(Ca2(1,3-pdta)2(H2O)2]·4H2O (4) have been obtained from the direct reactions of calcium salts with 1,3-propylenediaminetetraacetic acid in different pH values and solvents respectively (1,3-H4pdta = 1,3-propylenediaminetetraacetic acid). 1 is composed of one-dimensional chains bridged by 1,3-H4pdta, where only two strong coordination sites are offered by 1,3-H4pdta ligands. While complex 2 features a three-dimensional (3D) structural motif and 3 forms a 2D structure. 4 also contains one-dimensional chain constructed by dimeric calcium 1,3-propylenediaminetetraacetates. Solution 13C NMR spectra show that dimeric units in 3 dissociate into monomeric species in solution, which indicates that monomeric chelate is a dominant species in neutral and weak basic solution. It is notable that an obvious downfield shift (Δδ = 2.09 ppm) is observed for methanol in 3 that differs from methanol in D2O solvent.

A series of chiral and achiral neutral vanadyl complexes with N - heterocycle chelated ligands [V 2 O 2 ( S -lact) 2 (bpy) 2 ] ( 1 ), [V 2 O 2 ( S -lact) 2 (phen) 2 ] ( 2 ), [V 2 O 2 ( R -lact)( S -lact)(bpy) 2 ] ( 3 ), [V 2 O 2 ( R -lact)( S -lact)(phen) 2 ] ( 4 ) (H 2 lact = lactic acid, phen = 1,10-phenanthroline, and bpy = 2,2′-bipyridine) have been obtained under hydrothermal condition. The complexes feature bidentate lactate that chelates to vanadium atom through their α-alkoxido and carboxylato groups, while the other coordination sites are occupied by N - heterocycle ligand and terminal oxygen without coordinated or crystallized water molecule. Unusual short bond distances are observed for the coordinated lactates with V (IV) –O α-alkoxy and V (IV) –O carboxy 1.986(7) A in average, which imply the influence of full deprotonation in the chelated ring compared with those of 2.15 A in iron vanadium cofactor of V-nitrogenase. Enhanced activity and the red-shifts of vibrational circular dichroism (VCD) have been observed for the chiral neutral vanadyl complexes 1 and 2 and supported by B3LYP calculation. The carboxylato vibrations in VCD are observed in 1660, 1649, 1600, 1474, 1443 cm −1 and 1664, 1653, 1636, 1483, 1431 cm −1 for 1 and 2 respectively. Their absolute configurations of chiral metal center are assigned as Λ S . The EPR spectra of 1 and 3 with bpy ligands appear to be isotropic, while 2 and 4 with phen ligands display textbook rhombic EPR spectra, and the g values obtained are g xx 2.4727, g yy 1.9975, g zz 1.6456 for 2 ; and g xx 2.4585, g yy 1.9976, g zz 1.6412 for 4 respectively.

Water soluble coordination polymer of potassium lead 1,3-propylenediaminetetraacetate {K4[Pb2(1,3-pdta)2]·6H2O}n (1) and its insoluble products {[Pb(1,3-H2pdta)(H2O)]·2H2O}n (2), {[Pb2(1,3-pdta)(H2O)4]·4H2O}n (3) and [Pb2(1,3-pdta)(H2O)2]n (4) were obtained from the direct reactions of lead nitrate with 1,3-propylenediaminetetraacetic acid in different conditions (1,3-H4pdta=1,3-propylenediaminetetraacetic acid). The former 1 could be converted to the insoluble products of {[Pb2(1,3-pdta)(H2O)4]·4H2O}n (3) and [Pb2(1,3-pdta)(H2O)2]n (4) in weak acidic solution. The complexes have been full characterized by EA, FT-IR, solution and solid state 13C NMR spectra, thermogravimetric and structural analyses. Interestingly, 3 contains a unique (H2O)26 cluster and a 5.2 A pore after eliminating the guest water molecules, which exhibits reversible adsorption for methanol. This is confirmed by PXRD and solid state 13C NMR analyses. Nano-confined methanol in microporous structure has been observed based on the large downfield shift of 13C NMR signal (Δδ 9.72 ppm), attributing to the methyl group in methanol.

Dust suppression in coal mines is a worldwide problem which has not been solved effectively. The application of negative pressure secondary dust removal (NPSDR) is a breakthrough in the coal mine safety field. In this paper, NPSDR technology and ultrasonic dust suppression systems are introduced. High pressure water is supplied to the NPSDR device which is mounted on the shearer. A negative pressure field is formed in the device. At the same time, the dusty air around the shearer drum will be sucked into, and purged from, the NPSDR device by the negative pressure field. An ultrasonic dust suppression system uses water and compressed air to produce micron sized droplets which suppress respirable coal dust effectively. The NPSDR technology can be used for shearer dust suppression while ultrasonic dust suppression can be applied in areas such as the transportation positions. These dust suppression methods have the following advantages: high efficiency, wide applicability, simple structure, high reliability and low cost.