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Phosphogypsum (PG) is a typical by-product of phosphoric acid and phosphate fertilizers during acid digestion. The application of cemented paste backfill (CPB) has been feasibly investigated for the remediation of PG. The present study evaluated fluorine immobilization mechanisms and attempted to construct a related thermodynamic and geochemical modeling to describe the related stabilization performance. Physico-chemical and mineralogical analyses were performed on PG and hardened PG-based CPB (PCPB). The correlated macro- and microstructural properties were obtained from the analysis of the combination of unconfined compressive strength and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy imaging. Acid/base-dependent leaching tests were performed to ascertain fluoride leachability. In addition, Gibbs Energy Minimization Software and PHREEQC were applied as tools to characterize the PCPB hydration and deduce its geochemical characteristics. The results proved that multiple factors are involved in fluorine stabilization, among which the calcium silicate hydrate gel was found to be associated with retention. Although the quantitative comparison with the experimental data shows that further modification should be introduced into the simulation before being used as a predictive implement to determine PG management options, the importance of acid/base concentration in regulating the leaching behavior was confirmed. Moreover, the modeling enabled the identification of the impurity phases controlling the stability and leachability.

Copper corrosion in air containing sulfur dioxide atmosphere was described in detail, for which was one of the most primary atmospheric corrosion.In the first, effection from the synergy of pure sulfur dioxide gas and mixed gas on copper corrosion was set out, together with the introduction of certain corrosion products and formation mechanism. Besides, initial copper corrosion behaviors in variety gas concentration as well as different film thickness were summarized using electrochemical method. The research prospects were depicted in the last.

Two new complexes, [Cu(L1){N(CN)2}]·ClO4 (1) (L1 is 1,8-dimethyl-1,3,6,8,10,13-hexa-azacyclotetradecane) and [Co(L2)(N3)2]·ClO4 (2) (L2 is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane) have been synthesized and characterized. The compounds crystallize in the monoclinic system P21 space group for 1 and P21/n for 2. Single crystal X-ray analysis reveals that the compound 1 assumes a one-dimensional structure via hydrogen-bonding interactions, in which each Cu(II) ion is coordinated by four nitrogen atoms from ligand L1 and one nitrogen atom from [N(CN)2]− anion. For compound 2, each Co(III) ion is coordinated by four nitrogen atoms of ligand L2 and two nitrogen atoms from N3 − anion.

Two new complexes, {[MnAu 2 (CN) 4 (NITpPy) 2 (H 2 O) 2 ]} n ( 1 ) and {[Co(N(CN) 2 ) 2 (NITpPy) 2 (H 2 O) 2 ]} n ( 2 ), have been synthesized and characterized. The single-crystal X-ray analysis for the complexes 1 and 2 demonstrates that each M(II) (M = Mn or Co) ion assumes a distorted octahedral MN 4 O 2 coordination polyhedron. Four nitrogen atoms come from the cyanide groups and the pyridyl rings in a common plane, and two oxygen atoms come from the H 2 O molecules in trans -positions. The structures of complexes 1 and 2 illustrate that aurophilicity and/or hydrogen bonding interactions play important roles in increasing dimensionality. Magnetic investigations on complexes 1 and 2 show the presence of weak antiferromagnetic interactions.

A tetracyanometallate with complex dien cation [Fe(dien)2][Ni(CN)4] (1) (dien = diethylenetriamine), has been prepared and characterized by IR, UV-Vis and ESR spectroscopies. Single crystal X-ray analysis reveals that the compound assumes a ‘zero-dimensional’ structure in which one iron(II) ion is coordinated by six nitrogen atoms of the two dien ligands and the [Ni(CN)4]2− anion remains outside the coordination sphere. The six-coordinate iron(II) centres display a distorted octahedral arrangement.

Two novel 1D complexes, [Ni(hto){Au(CN)2}2][Ni(hto)](ClO4)2 · 4H2O (hto = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.16,9]octadecane, in Scheme 1.) (1) and [Co(dien)2][{Au(CN)2}3] · 2H2O (dien = diethylenetriamine) (2) have been synthesized and characterized. The crystal structure of 1 confirmed the presence of nickel (II) chains via Au–Au interactions. The coordination geometry around the six-coordinate nickel (II) ion is slightly distorted octahedral with four nitrogen atoms of the macrocycle and two nitrogen atoms of the cyanides. The presence of Au–Au interactions have effectively increased the zero dimensional coordination polymer to a one dimensional system. In the complex 2, there are one cation, three anions, and two water molecules in the asymmetric unit. These components are interconnected through a combination of aurophilic attractions and hydrogen bonds and formed 1D chains.

By using the macrocyclic oxamido-copper(II) complex as a building block and N 3 - and Cl- as auxiliary bridged groups, a binuclear complex and two tetranuclear complexes derived from the binuclear species have been prepared by stepwise synthesis and characterized. Their formulas are Cu(μ-exoO 2 )cyclam (1), [Cu(μ-exoO 2 )cyclamCu-(tmen)](ClO 4 ) 2 .H 2 O (2), {[Cu(μ-exoO 2 )cyclamCu(μ-1,3-N 3 ) 0.5 (tmen)] 2 {ClO 4 )4, [Cu(μ-exoO 2 )cyclamCu(μ-1,3-N 3 ) 0.5 (tmen)] 2 -(ClO 4 ) 2 } (3), and [Cu(μ-exoO 2 )cyclamCu(μ-Cl) 0.5 (tmen)] 2 (ClO 4 )3 (4), where tmen = N,N,N'N'-tetramethylethylene-diamine and (exoO 2 )cyclam = 1,4,8,11-tetraazacyclotradecanne-2,3-dione. The structure of complex 1 consists of the neutral copper(II) complex of the [14]N 4 macrocyclic oxamido dianion, and the packing of the molecules along the b orientation results in a novel one-dimensional wavelike chain through weak coordination bonds and hydrogen bonds. The structure of complex 2 consists of binuclear cations, a weakly coordinated water molecule, and perchlorate anions, and the structures of 3 and 4 consist of tetranuclear cations derived from binuclear species through azide and chloride ligands, respectively, and perchlorate anions.

A cyano-bridged nickel(II) compound, {[Ni(hto)][Ni(CN) 4 ]·( i -C 3 H 7 OH)·2H 2 O} n (hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9 ]octadecane, in Scheme 1), has been prepared and characterized. Single crystal X-ray analysis reveals that the compound assumes a one-dimensional structure in which one nickel(II) ion is coordinated by four cyanide ligands and the other is coordinated by four nitrogen atoms of the macrocyclic ligand and two nitrogen atoms of the bridging cyanide ligands. The six-coordinate nickel(II) centres display an axially elongated octahedron, whereas the four-coordinate nickel(II) centres assume planar geometry. The polar guest isopropanol and water molecules are accommodated among [–Ni(hto)–NC–Ni(CN) 2 –CN–] n chains. The interguest and host–guest hydrogen-bonds formation link the chains and stabilize the whole crystal structure.

A new complex, [Cu(dien)2][Ni(CN)4] (1) [dien = diethylenetriamine] has been obtained by the reaction of Cu(ClO4)2·6H2O, diethylenetriamine and K2[Ni(CN)4] in water, and has been characterized spectroscopically. The crystal structure of 1 has been determined. In the complex, two tridentate dien ligands are bonded to the copper(II) ion in a distorted octahedral arrangement and the anion remains outside the coordination sphere.

A three-dimensional cyano-bridged copper(II) complex, [Cu(dien)Ag(CN)2]2[Ag2(CN)3][Ag(CN)2] (1) (dien = diethylenetriamine), has been prepared and characterized by X-ray crystallography. Complex 1 crystallized in the monoclinic space group P21/n with a = 6.988(2), b = 17.615(6), c = 12.564(4) A, β = 90.790(5)°. The crystal consists of cis-[Cu(dien)]2+ units bridged by [Ag(CN)2]— to form a zig-zag chain. The Ag atoms of the free and bridging [Ag(CN)2]— link together to form additional infinite zig-zag chains with short Ag···Ag distances. The presence of Ag···Ag interactions effectively increases the dimensionality from a 1-D chain to a 3-D coordination polymer.

A new Prussian-blue type molecular magnet containing a paramagnetic [Cr(CN)5(NO)]3− building block has been synthesized and characterized; the observed magnetic behavior displays the nature of a ferrimagnet.

A novel complex, [[CoAu2(CN)4(NITpPy)2(H2O)2]]n, 1, containing the cobalt(II) ion, dicyanoaurate(I) anion, and nitronyl nitroxide radical building blocks, has been prepared and structurally characterized by single-crystal X-ray analysis. The structure of complex 1 illustrates that aurophilicity and hydrogen bonding interactions increase dimensionality, generating a 2-D interdigitating system. The spectroscopic and magnetic properties have been investigated.

A three-dimensional cyano-bridged copper(II) complex, [Cu(dien)Ag(CN)2]2[Ag2(CN)3][Ag(CN)2] (1) (dien = diethylenetriamine), has been prepared and characterized by X-ray crystallography. Complex 1 crystallized in the monoclinic space group P21/n with a = 6.988(2), b = 17.615(6), c = 12.564(4) A, β = 90.790(5)°. The crystal consists of cis-[Cu(dien)]2+ units bridged by [Ag(CN)2]— to form a zig-zag chain. The Ag atoms of the free and bridging [Ag(CN)2]— link together to form additional infinite zig-zag chains with short Ag···Ag distances. The presence of Ag···Ag interactions effectively increases the dimensionality from a 1-D chain to a 3-D coordination polymer.

Two new supramolecular polymeric coordination complexes, {Zn(phen)2[Au2(CN)4](H2O)}·1.5H2O 1 and {Mn(phen)[Au2(CN)4](H2O)}·PriOH 2, have been obtained through a self-assembly process. The three-dimensional supramolecular architectures of compounds 1 and 2 are sustained by aurophilic, hydrogen-bonding, and/or π–π interactions. Gold atoms linked with aurophilic bonds arrange in a pattern not frequently observed.

Two self-assembled supramolecular architectures {{MnH2O(Phen)2[Au(CN)2]}[Au(CN)2]·0.5C2H5OH·0.5H2O}n (phen = 1, 10-phenanthroline) (1) and [C6H13N4][Au(CN)2]·H2O(C6H13N4 = 4-amide-3, 5-diethyl-1, 2, 4-triazole cation) (2) have been synthesized and structurally characterized. X-ray crystallography revealed a three-dimensional structure of 1 formed by the incorporation of coordinative linkage, aurophilic, hydrogen-bonding and π–π interactions. The 2D structure of 2 is formed by aurophilic and hydrogen-bonding interactions. Both the solid phases and aqueous solutions of 1 and 2 display interesting luminescence at room temperature.