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Grassland exclosures with fencing are commonly used to prevent shrub encroachment. However, few studies have been conducted on the effect of exclosures on soil macropores and root architecture during shrub encroachment. This study aimed to quantify the effects of exclosures on soil macropore and root characteristics beneath the encroached shrub C. microphylla L. in the Inner Mongolia grassland. Two exclosure treatments, 9EX (shrubland enclosed for 9 years) and 2EX (shrubland enclosed for 2 years), were designed, with free grazing plots serving as controls. A total of twelve soil cores (0–50 cm deep) were excavated, which included three replicates of each treatment and control. Soil and root architecture of the soil cores were explored using X-ray computed tomography method. Results indicated that macroporosity was 1.03–1.66 times greater in the soil under the enclosed C. microphylla L. than in the soil under the grazed C. microphylla L., and the soil macroporosity increased with exclosure age. Macropores were abundant over the 0–400 mm soil layers under the enclosed shrubland but were mainly present at 0–250 mm soil depth under freely grazed shrubland. Exclosure led to significant proliferation of shrub roots compared with grazing. Root density was 1.04–1.86 times greater in the soil under the enclosed C. microphylla L. than in the soil under the grazed C. microphylla L. Roots were concentrated in the 0–250 mm soil layer in the grazed shrubland, whereas roots were abundant over 0–400 mm in the enclosed shrubland. The high number of macropores under the enclosed shrubland was closely associated with a high root density. These results suggest that exclosure enhances shrub root proliferation and therefore increases soil macroporosity and soil pore connectivity, which would be favourable for shrub encroachment.

The relationship between soil macropore and plant roots warrants special attention because it influences the behavior of water in soil. However, the influence of shrub roots on soil macropores in shrub-encroached grasslands is poorly understood. The objectives of this study were to quantify soil macropores and root architecture in a shrub-encroached grassland in northern China, and to reveal the relationship between shrub roots and soil macropore. In this study, treatments were performed that corresponded to three successional states of the shrub C. microphylla L. with three different shrub densities. At each site, three undisturbed soil cores were excavated under the shrub canopies, and a Philips medical scanner was used to simultaneously visualize and quantify the soil and root architectures. Strong positive correlations between root volume, length, and surface area and the solid surface/solid volume ratio were found, and greater root growth was noted in more porous soil. The results highlighted that the soil macropore characteristics corresponded well with the root characteristics of the soils for the three treatments. Soil macroporosity and macropore volume increased with increasing shrub root network density. In addition, the influence of plant roots on soil macropores increased with increasing shrub encroachment. The study confirmed that the large number of macropores found in the soils under shrubs was attributed to the great degree of root development there. The greater degree of macroporosity under shrubs was attributed to the larger root network density, which might cause greater amounts of water to be concentrated in the deep soil layer by macropore flow under shrub patches. The influence of plant roots on soil macropores increased with increasing shrub encroachment.

Grassland exclosure is a widely-used option to prevent from grazing in degraded grasslands for restoration. However, the influence of exclosure on soil macropore of grassland remain scarce. The objective of this study was to quantify the pore architecture of grassland soils under exclosure. Two treatments, 9E (grassland enclosed for 9 years) and 5E (grassland enclosed for 5 years), were designed, with grazing as a control in the experiment. Nine soil columns (0–50 cm deep) were taken at the three sites with three replicates. At each site, three soil columns were from the grassland, and cores were scanned with a Philips Brilliance ICT Medical Scanner. Numbers of macropores, macroporosity, network density, length density, and node density within the 50-cm soil profile were interpreted from X-ray computed tomography to analyze soil pore architecture. The results indicated that exclosure significantly influenced CT-measured soil macroporosity in the Inner Mongolia grassland of northern China. Soils under enclosed grassland had greater macroporosity, length density, total volume, and node density than that of under freely grazed grassland. Macroporosity increased as the enclosure age increased. For soils under enclosed grassland, macropores were concentrated at 0–300-mm soil layers, and macropores were mainly present at 0–100-mm soil depth under freely grazed grassland. The large number of macropores found in soil under enclosed grassland can be attributed to greater root development. Exclosure increases soil macroporosity and improve soil structure.

The title complex [(H2O)2(IMI)3Ni(TCB)Ni(IMI)3-(H2O)2] H2O (TCB = 1,2,4,5-benzenetetracarboxylato te-travalent anion; IMI = imidazole) has been prepared by the reaction of Ni(IMI)3(Ac)2 and TCB in aqueous solution. The crystal structure has been determined by single-crystal X-ray diffraction method. It crystallizes in the monoclinic system, space group P21/c(# 14), a = 1.2714(4) nm, b = 0.9411 (3) nm, c = 1.5869(4) nm, β= 108.54(2)°, V= 1.8001(9) nm3, Z = 2. The main feature of the crystal structure is a symmetric binuclear unit made up of two slightly distorted coordination octahedrons, which are bridged by TCB in monodentate fashion to each metal ion. Moreover three nitrogen atoms from three imidazoles, three oxygen atoms from two water molecules and one carboxylate group of TCB coordinated to a nickel (I) ion are found on a face of the octahedron respectively, so the octahedron is a facial isomer.

Lanthanum(III) and europium(III) complexes of 1,10-phenanthroline (phen) with 5-nitroisophthalate, [La(phen)(HNip)(Nip)] n (1) and [Eu(phen)(HNip)(Nip)] n (2), have been synthesized and characterized by elemental analysis and IR spectroscopy and studied by X-ray crystallography. The single crystal X-ray analyses show that both lanthanum(III) and europium(III) are coordinated by two nitrogens of phen and six oxygens from “Nip2−” and “HNip−”, resulting in a distorted square antiprism.

A 2D ZnII(μ-4,4′-bipy) coordination polymer with 1,4-naphthalenedicarboxylate, {[Zn(μ-4,4′-bipy)(1,4-ndc)(H2O)2] · (H2O)} n , has been synthesized, characterized and studied by X-ray crystallography. The structural studies show the Zn atoms have six-coordinate geometry with a distorted octahedral environment. The 2D structure is grown by hydrogen bonds into a hybrid three-dimensional network.

The single crystal X-ray analysis of a novel thiophene-2,5-dicarboxylic acid (H2Tda) Manganese(II) coordination polymer, {Mn2(μ3-Tda)2(μ-H2O)(H2O)2(bipy)]·DMF}n, shows two different types of Mn2+-ions with environment of Mn1O6 and Mn2O4N2, and the complex is a two-dimensional polymer as a result of bridging (Tda)2− ligands and by connecting the carboxylate- and water-bridged {Mn2(μ-Tda)2(μ-H2O)} nodes.

In the title compound, (NH4)[ZnCl3(C6H12N4)]·1.5H2O, the ZnII atom is in a tetra­hedral environment, coordinated by one N atom of the hexa­methyl­enetetra­mine ligand and by three Cl atoms. The charge of the hexa­methyl­enetetra­mine­trichloro­zincate(II) anion is counter-balanced by an ammonium cation. Two water mol­ecules, one of which shows disorder and is only partly occupied, are also present. The structure is stabilized by weak inter­molecular O—H⋯N, N—H⋯O and N—H⋯N hydrogen bonds.

In the title compound, [Cu(C12H8N2)(C7H4SO5)(H2O)]·C3H7NO, the CuII atom has a square-pyramidal coordination geometry formed by three O atom and two N atoms. The 1,2-di-4-pyridylethyl­ene ligands function as μ2-bridging ligands to form a zigzag chain. The 2-sulfonatobenzoate ligands protrude on alternate sides of the chain. Inter­molecular O—H⋯O hydrogen bonds link the chains into a two-dimensional network structure.

In the polymeric title compound, [Cu(im)Cl(phen)](n), where im is the imidazolate anion (C(3)H(3)N(2)) and phen is 1,10-phenanthroline (C(12)H(8)N(2)), each Cu(II) ion is five-coordinated by four basal N atoms (two from two different im anions and two from one phen ligand) and one axial Cl atom, in a distorted square-pyramidal coordination geometry. Moreover, each im anion bridges two identical [CuCl(phen)](+) cations through its two N atoms, resulting in a one-dimensional zigzag chain along the crystallographic a axis. In addition, pairs of adjacent chains are staggered by pi-pi interactions, generating a two-dimensional layer, and neighbouring layers are further linked by two different kinds of C-H...Cl interactions, producing a three-dimensional network.

In the title compound, [Co(C10H4O8)(C12H8N2)(H2O)3]·H2O, the Co atom has an octahedral coordination geometry, involving three aqua O atoms, one carboxyl­ate O atom and two N atoms from a 1,10-phenathroline (phen) mol­ecule. O—H⋯O hydrogen bonds involving di­hydrogen-1,2,4,5-benzenetetra­carboxyl­ate (H2TCB) anions, aqua ligands and uncoordinated water mol­ecules, along with π–π interactions between the phen and aromatic rings of symmetry-related H2TCB anions, link the mononuclear units into a three-dimensional network structure.

In bis(1,10-phenanthroline)­di­azido­nickel(II), [Ni(C12H8N2)2(N3)2], the nickel atom is chelated by the two heterocyclic ligands in a distorted octahedral geometry; the two azido groups occupy cis-positions in the coordination polyhedron.

In the polymeric title compound, [Cu(im)Cl(phen)](n), where im is the imidazolate anion (C(3)H(3)N(2)) and phen is 1,10-phenanthroline (C(12)H(8)N(2)), each Cu(II) ion is five-coordinated by four basal N atoms (two from two different im anions and two from one phen ligand) and one axial Cl atom, in a distorted square-pyramidal coordination geometry. Moreover, each im anion bridges two identical [CuCl(phen)](+) cations through its two N atoms, resulting in a one-dimensional zigzag chain along the crystallographic a axis. In addition, pairs of adjacent chains are staggered by pi-pi interactions, generating a two-dimensional layer, and neighbouring layers are further linked by two different kinds of C-H...Cl interactions, producing a three-dimensional network.

In the title compound, [Cu(C(5)H(4)ClNO)(2)(C(4)H(4)N(2))(H(2)O)(2)](ClO(4))(2), the Cu atom, which lies on an inversion centre, has an octahedral environment. The pyrazine ligand also lies about an inversion centre and links adjacent Cu atoms into a chain running along the b axis; perchlorate anions occupy the space between the chains, and the chains use the coordinated water molecules to link to the anions, resulting in a hydrogen-bonded ribbon structure. The donor 5-chloro-2-hydroxypyridine ligand exists in the zwitterionic form, i.e. 5-chloropyridinium-2-olate.

The title mol­ecule, C18H18O8, has C2 molecular symmetry. In the crystal structure, each mol­ecule is connected to four neighbours via intermolecular O—H⋯O hydrogen bonds to form a two-dimensional network parallel to (100).

In the title complex, C8H12N2·2C6H5NO3, one 2,3,5,6-tetra­methyl­pyrazine and two p-nitro­phenol mol­ecules form a centrosymmetric unit. Intermolecular O—H⋯N and weak C—H⋯O hydrogen bonds are observed in the structure, leading to the formation of a two-dimensional network.

In the title compound, [Ni(C14H8O5)(C10H8N2)]n, the NiII atom is coordinated by four O atoms of two 4,4′-oxydibenzoate (oba) dianions and two N atoms of a chelate 2,2′-bipyridine ligand to furnish a distorted octahedral coordination environment. The V-shaped oba dianion acts as a bridge between two Ni atoms to form a zigzag chain coordination polymer.

In the title compound, [Cu(C8H3NO6)(C10H8N2)]n, the Cu atom exists in a four-coordinate environment defined by two carboxyl O atoms belonging to two 5-nitro­isophthalate dianions and two N atoms from a 2,2′-bipyridine molecule. The 5-nitro­isophthalate dianion acts as a bridge between two Cu atoms in a tris-monodentate coordination mode, resulting in a zigzag coordination polymer.

In the title compound, [Mn(N3)2(C10H8N2)2], the Mn atom, on a twofold rotation axis, is chelated by the two heterocyclic ligands, with the two azide groups in cis positions in the distorted octahedral coordination.

In the title compound, [Cu2(mu-(1,3)-N3)(N3)2(phen)4](N3)*4H2O (phen is 1,10-phenanthroline, C12H8N2), each of the two Cu atoms is surrounded by two N atoms of two azide anions and by four N atoms of two 1,10-phenanthroline ligands [Cu-N distances are 1.964 (3), 2.009 (3), 2.018 (3), 2.054 (3), 2.306 (3) and 2.759 (4) A], forming an elongated CuN6 octahedron. An ideally linear mu(1,3)-azide anion bridges two Cu atoms to form a dimeric structure with the central N atom located on a centre of inversion. Moreover, the adjacent dimeric units are connected by hydrogen-bond interactions to produce one-dimensional chains. A two-dimensional supramolecular array is formed by pi-pi interactions between the aromatic rings of 1,10-phenanthroline ligands of adjacent dimeric units.