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Single crystals of the β polymorph, formic acid and propanoic acid solvates of the title compound (abbreviation APPP) have been obtained. Single-crystal X-ray analysis revealed that the APPP molecules in the β polymorph construct the homochiral helical chains and the pyrene fluorophores adopt a monomer arrangement. Analogous structures were also found in the two solvates, while a small π-overlap exists between the pyrene fluorophores. Moreover, apart from the acetic acid solvate (form I) in a previous report, a new crystalline form (form II) was discovered through a rapid crystallization method and confirmed by PXRD patterns. The thermal and optical-physical properties of these crystals were investigated. All the three solvates could transform into the β polymorph after desolvation, but the pure β polymorph could be isolated only from the formic acid solvate. The optical properties are closely related to the pyrene fluorophore stacking modes and intermolecular interactions in the solid-state. The immobilization of pyrene fluorophores may be responsible for the high quantum yields. [ABSTRACT FROM AUTHOR]

C26H22N2O2, monoclinic, P21/c (no. 14), a = 16.4367(8) Å, b = 12.7804(6) Å, c = 19.5474(8) Å, β = 96.1700(14)°, V = 4082.5(3) Å3, Z = 8, Rgt(F) = 0.0516, wRref(F2) = 0.1195, T = 273(2) K. [ABSTRACT FROM AUTHOR]

By changing the N -donor ancillary ligand, three novel silver (I) complexes {[Ag(HbzgluO) (4,4′-bipy)]·H 2 O} n ( 1 ), {[Ag 2 (HbzgluO) 2 (bpe) 2 ]·2H 2 O} n ( 2 ) and {[Ag(HbzgluO)(bpp)]·2H 2 O} n ( 3 ) (H 2 bzgluO = N -benzoyl- l -glutamic acid, 4,4′-bipy = 4,4ˊ-bipyridine, bpe = 1,2-di(4-pyridyl)ethane, bpp = 1,3-di(4-pyridyl)propane) were synthesized. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). In this study, the N -donor ligands are changed from rigidity (4,4′-bipy), quasi-flexibility (bpe) to flexibility (bpp), the structures of complexes also change. Complex 1 features a 1D chain structure which is further linked together to construct a 2D supramolecular structure through hydrogen bonds. Complex 2 is a 1D double-chains configuration which eventually forms a 3D supramolecular network via hydrogen bonding interactions. Whereas, complex 3 exhibits a 2D pleated grid structure which is linked by hydrogen bonding interactions into a 3D supramolecular network. The present observations demonstrate that the modulation of coordination polymers with different structures can accomplish by changing the spacer length of N -donor ligands. In addition, the solid-state circular dichroism (CD) spectra indicated that compound 2 exhibited negative cotton effect which originated from the chiral ligands H 2 bzgluO and the solid-state fluorescence spectra of the three complexes demonstrated the auxiliary ligands have influence on the photoluminescence properties of the complexes. [ABSTRACT FROM AUTHOR]

Three high-energy salts ( 3 , 4 and 5 ) based on oxy-bridged bis( gem -dinitro) furazan with potassium and nitrogen-rich cations were reported. Their structures were fully characterized and confirmed by NMR ( 1 H, 13 C), IR spectroscopy, elemental analysis and single crystal X-ray diffraction. The thermal decomposition behaviors were studied by DSC and TG methods. And, the decomposition process of 5 was studied by the thermolysis in-situ rapid-scan FTIR. The non-isothermal kinetics parameters were obtained by Kissinger’s and Ozawa’s methods, respectively. The activation entropy (Δ S ≠ ), activation enthalpy (Δ H ≠ ), activation Gibbs free energy (Δ G ≠ ) and the critical temperature of thermal explosion were calculated. [ABSTRACT FROM AUTHOR]

Highlights: [•] N-Benzoyl-l-glutamic coordination polymers. [•] Different N-donor ancillary ligands. [•] Strong fluorescence properties. [Copyright &y& Elsevier]

By controlling the concentration of the reaction system, two zinc(II) complexes, [Zn2(tsgluO)2(phen)2]n(1) and [Zn2(tsgluO)2(phen)2(H2O)2] (2) (H2tsgluO = N-tosyl-L-glutamic acid, phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analysis, infrared spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. Complexes1and2both crystallize in the triclinic space group P-1. Complex1exhibits a 1-D double-chain structure. Complex2has a dinuclear structure which is extended by hydrogen-bonding interactions to form a 2-D supramolecular network. The structural difference indicates that the concentration plays a crucial role in modulating structures of coordination complexes. The two compounds also show intense fluorescence at room temperature. [ABSTRACT FROM PUBLISHER]

1-Acetyl-3-phenyl-5-(1-pyrenyl)-pyrazoline(APPP) was synthesizedand formed four types of different crystals under different crystallizationconditions: guest-free crystal (I, α polymorph),APPP·chloroform solvate (II), APPP·phenol cocrystal(III), and APPP·acetic acid solvate (IV). Twisted structures and different stacking modes of APPP moleculeswere found in the four crystals. Single crystal X-ray analyses revealedpyrene fluorophores adopt an edge-to-face π-stacked arrangementin crystal I, mononer arrangement in crystals II and III, and face-to-face slipped π-stacked arrangementin crystal IV. Another phase (β polymorph) wasdiscovered during DSC experiments of crystals IIand IVand obtained by desolvation of crystal II.However, solvent-mediated phase transitions revealed β polymorphis a metastable phase at room temperature, and no single crystal couldbe isolated. The optical–physical properties of these solidswere investigated. Crystal Ishows a broad emission band(λmax= 419 nm) with a red shift of about 40 nm relativeto its flurescence in solvents, in which the vibrational featuresare less clear. The spectra of crystals IIand IIIand β polymorph are similar to each other, exhibitingthe shortest λem(λmax= 399–400nm), and the fluorescence spectra with vibrational features are closeto pyrene fluorescence in solvents. In contrast, crystal IVshows structureless and broad emission spectrum with the longestλem(λmax= 452 nm) among thesecrystals. The difference in their optical–physical propertiesis closely related to the different arrangements of pyrene fluorophores.The monomer arrangements of pyrene fluorophores may be responsiblefor the shortest λem, higher emission quantum yields,and longer lifetimes. For a given organic luminescent material, thestrategy based on the solvates and cocrystals can not only tune theoptical–physical properties but also be helpful to find suitablepolymorphic phases. [ABSTRACT FROM AUTHOR]

Highlights: [•] 4-Amino-3,5-dinitropyrazole potassium salt (ADNPK) of a novel energetic flame suppressor was synthesized. [•] The single crystal of ADNPK was determined by single crystal X-ray diffraction. [•] The thermal behavior and non-isothermal decomposition reaction kinetics of ADNPK were studied by nonisothermal DSC. [ABSTRACT FROM AUTHOR]

The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field and different phonon modes including interface, confined and half-space phonon modes are considered in our calculation. The results for a zinc-blende quantum well are also given for comparison. It is found that the main contribution to the transition energy comes from half-space and interface phonon modes when the well width is very small while the confined modes play a more important role in a wider well due to the location of the electron wave function. As the well width increases, the cyclotron mass of magnetopolarons first increases to a maximum and then decreases either with or without the built-in electric field in the wurtzite structure and the built-in electric field slightly reduces the cyclotron mass. The variation of cyclotron mass in a zinc-blende structure is similar to that in a wurtzite structure. With the increase of external magnetic field, the cyclotron mass of polarons almost linearly increases. The cyclotron frequency of magnetopolarons is also discussed. [ABSTRACT FROM AUTHOR]

• The influence of temperature on constructuring enantiomeric coordination polymers. • The influence of ancillary ligand on constructuring enantiomeric coordination polymers. • The luminescent properties of enantiomeric coordination polymers in the solid state. Three new Pb(II) coordination polymers, namely [Pb 2 (mand) 2 ] n (1), {[Pb(L -Hmand)(NO 3)(5,5′-DM-2,2′-bipy)]·2H 2 O} n (2- L ), {[Pb(D -Hmand)(NO 3)(5,5′-DM-2,2′-bipy)]·2H 2 O} n (2- D ) (H 2 mand = D / L -mandelic acid, 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridyl), have been prepared. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, powder X-ray diffraction and thermogravimetric analyses. Complex 1 crystallizes in the triclinic system with space group P -1, and displays a 2D layer structure. Complexes 2- L and 2- D are pairs of enantiomers. They crystallize in the same chiral space group P 2 1 2 1 2 1 and feature a 1D chain structure. The influence of the temperature and steric-hinerance of 5,5′-dimethyl-2,2′-dipyridyl molecules on constructing enantiomeric Pb(II) coordination polymers based on chiral mandelic acid ligands have been demonstrated. In addition, the circular dichroism (CD) spectroscopy of 2- L and 2- D exhibit obvious positive or negative Cotton effects indicating their homochirality. The luminescent properties of 1 , 2- L and 2- D in the solid state have also been investigated. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of oxy-bridged bis(1 H -tetrazol-5-yl)furazan ( 2 ) were reported. The thermal behavior of 2 was investigated by DSC and TG–FTIR–MS coupling technique. The results showed that the thermolysis of 2 included two stages. The rupture of tetrazole ring occurred with the release of N 2 in the first stage. In the second stage, the striping of HCN from schiff base radical followed by the fragmentation of furazan ether moiety, which leading to the formation of N 2 O, NO and polymer. Furthermore, two decomposition pathways of 2 under electron impact condition were proposed, and the fracture of tetrazole ring and ether bond were considered as the initial step of molecule decomposition, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] The crystal structure of the new ionic compound DAT·DNBA was determinated and analyzed. [•] The thermal behavior and the decomposition reaction kinetics were investigated by means of DSC and RSFTIR. [•] Some parameters were calculated to evaluate the thermal stability and safety. [ABSTRACT FROM AUTHOR]

Three new energetic compounds, nickel(II) 3,5-dinitro-2-pyridonate (Ni(2DNPO)2(H2O)4, 1), copper(II) 3,5-dinitro-4-pyridonate (Cu(4DNPO)2(H2O)4, 2) and cobalt(II) 3,5-dinitro-4-pyridone-N-hydroxylate ([Co(4DNPOH)2(H2O)4] · 2DMF, 3 · 2DMF), were characterized by elemental analysis, FT-IR, TG-DSC and X-ray single crystal diffraction analysis. Complexes 1 and 2 are similar in structure with the metal ion coordinated by oxygen donors of four water molecules on the equatorial position and two nitrogen donors of the pyridone rings of two ligands in the axial positions. The cobalt(II) complex 3 · 2DMF is a heavily distorted octahedral geometry. The Co(II) has equatorial positions defined by oxygens of four water molecules. Its axial positions are filled with two oxygen atoms of the pyridone-N-hydroxylate of two ligands. The TG-DSC results reveal that 1 is the most stable, with higher initial thermal decomposition temperature and enthalpy. Based on the thermoanalyses, the nickel compound is a promising candidate as a component in catalyzed RDX-CMDB propellants in comparison with our earlier lead(II) analogs. [ABSTRACT FROM AUTHOR]

A new high-nitrogen compound [Mn(ATZ)(H2O)4]·2H2O (ATZ=5,5-azotetrazolate) was synthesized. Crystal structure and elemental, IR and thermal analyses were investigated in the present work. It crystallized in triclinic space group P-1 with lattice parameters a =6. 304(2)Å, b =7. 004(2)Å, c =7. 921(3)Å, α =76. 114(5)°, β =74. 023(5)°, γ =69. 254(4)°. TG-DTG and DSC measurements are employed to postulate the thermal decomposition mechanism. The thermal decomposition kinetics of the main exothermic reaction was investigated by non-isothermal method and obtained its enthalpy of decomposition and the probable kinetic mechanism. An attempt was made to incorporate the relation between thermal stability and the structure. [Copyright &y& Elsevier]

Ni(NH3)4(AFT)2 [NiC6H16N18O2, AFT = 4-amino-3-(5-tetrazolate)furazan] is synthesized and characterized by elemental analysis and Fourier-transform infrared spectroscopy for the first time. X-ray diffraction measurements are used to determine the crystal structure of compound 1. The results demonstrate that compound 1 crystallized in the orthorhombic crystal system. The nickel(II) ion is six-coordinated by N atoms from two AFT-ligands and four NH3 molecules. Its thermal properties are investigated by differential scanning calorimetry and thermogravimetry-derivative thermogravimetry methods, with the results demonstrating that the differential scanning calorimetry curve exhibits two endothermic and one exothermic processes. The endothermic processes are in the range of 130–510 °C with a peak temperature of 188 °C. The temperature from 230 to 400 °C is the exothermic process in which the peak temperature is 314.58 °C. In addition, Kissinger's and Ozawa-Doyle's methods are used for calculating the non-isothermal kinetics parameters. Moreover, the apparent activation energy (E), safety, and thermal stability parameters (T SADT, T TIT, T b) for Ni(NH3)4(AFT)2 are calculated. In addition, the calculated thermodynamic functions (∆S ≠, ∆H ≠, and ∆G ≠) for the exothermic decomposition process of Ni(NH3)4(AFT)2 are 55.07 J mol−1 K−1, 196.18 kJ mol−1, and 164.90 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]

In this study, 1-acetyl-3-(3-hydroxyphenyl)-5-(9-anthracenyl)-2-pyrazoline (AHAP) was synthesized and afforded two types of polymorphs. Single crystal X-ray analyses revealed that AHAP molecules connect with each other in a head-to-tail fashion through O-H⋯O hydrogen bonds between the carbonyl and hydroxyl groups. However, through the above intermolecular interactions and stacking mode, the one-dimensional chain motifs are formed in the α polymorph and cyclic tetramers are formed in the β polymorph, which constitute their crystal structures as units. Compared with solvent-free α polymorph, the unit cell of the β polymorph includes a small region of disordered solvent molecules. CrystalExplorer program, Differential scanning calorimetry (DSC) and thermogravimetric thermal analysis (TGA) experiments revealed that the voids should be inside the tetramers and each void contains one disordered solvent molecule. 1H NMR spectra conformed the type of the disordered solvent molecule is consistent with the crystalline liquid phase. The optical-physical properties of the two polymorphs were also investigated. They emit similar fluorescence, which is assigned to monomer emission of anthracene, due to the monomer arrangement of anthracene fluorophores in the two polymorphs. Image 1 • The identical O-H⋯O hydrogen bonds induced polymorphism of pyrazoline derivative. • High stability of the two polymorphs due to the strong hydrogen bonds. • One-dimensional chain motifs and tetramer structure formed by hydrogen bonds, respectively. [ABSTRACT FROM AUTHOR]

The layered niobium oxide H 4 Nb 6 O 17 (HNO) crystal has an open layered structure. The H 2 O 2 molecules can enter rapidly into the interlayers of HNO crystal, and coordinate with Nb within NbO 6 octahedron to form the peroxy bond intercalated HNO crystal (P-HNO). The introduction of peroxy bond causes the positive shift of the CB minimum of HNO crystal from −0.39 eV to 0.42 eV, resulting in its band gap narrowing from 3.49 eV to 2.68 eV and the improvement of visible light absorption. The photocatalytic investigation indicates that such P-HNO crystal has the visible light photocatalytic performance for RhB dye degradation. Moreover, the trapping experiment indicates that h + and Image 2 are the main active species during the visible light photocatalytic degradation of RhB dye. And the study of photocatalytic degradation mechanism shows that there is a synergy between P-HNO crystal and RhB during the photodegradation of RhB. [ABSTRACT FROM AUTHOR]

InAs/InAsSb superlattices were grown on (0 0 1) GaSb substrates by metal organic chemical vapor deposition for potential applications as mid-infrared optoelectronic devices. X-ray diffraction, transmission electron microscopy, photoluminescence emission and spectral photoconductivity were used to characterize the grown structures. Generally, photoluminescence emission measurements of InAs/InAsSb superlattices were performed over the temperature range from 11 K to 300 K. The Varshni and Bose–Einstein parameters were determined. Low-temperature photoluminescence measurements showed peaks at 3–5 μm, while photoconductance results showed strong spectral response up to room temperature, when the photoresponse onset was extended to 5.5 μm. The photoluminescence emission band covers the CO 2 absorption peak making it suitable for application in CO 2 detection. [ABSTRACT FROM AUTHOR]

A new cadmium complex of 1,1-diamino-2,2-dinitroethylene (FOX-7) was synthesized and structurally determined. Central Cd2+is coordinated by six nitrogens from four NH3molecules and two FOX-7?anions to form an octahedral structure. The thermal decomposition of Cd(NH3)4(FOX-7)2was studied with differential scanning calorimeter and TG–DTG methods. The apparent activation energy and pre-exponential constant of the exothermic process are 220.6 kJ M?1and 1017.86s?1, respectively. Cd(NH3)4(FOX-7)2is sensitive. [ABSTRACT FROM AUTHOR]

A new energetic zinc-FOX-7 complex (FOX-7 = 1,1-diamino-2,2-dinitroethylene), Zn(NH3)2(FOX-7)2, was synthesized and structurally characterized by single crystal X-ray diffraction. Zn2+was coordinated by four nitrogens from two ammonias and two FOX-7?anions, forming a distorted tetrahedron. Thermal decomposition of Zn(NH3)2(FOX-7)2was studied by differential scanning calorimetry and thermogravimetry/differential thermogravimetry. The apparent activation energy and pre-exponential constant of the first decomposition process are 144.8 kJ M?1and 1013.99?s?1, respectively. The self-accelerating decomposition temperature and critical temperature of thermal explosion of Zn(NH3)2(FOX-7)2are 183.2 and 195.8?°C, respectively. The thermal stability of Zn(NH3)2(FOX-7)2is good, but Zn(NH3)2(FOX-7)2is still sensitive. [ABSTRACT FROM PUBLISHER]

Two energetic strontium(ll) complexes with nitrogen-rich 3,6-bis(lH-l,2,3,4-tetrazol-5-yl-amino)- 1,2,4,5-tetrazine (BTATz) were synthesized. The metal complexes were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. DSC and TG-DTG were used to study the thermal behavior, non-isothermal decomposition reaction kinetics, self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTTT). critical temperature of thermal explosion (Tb), and the adiabatic time-to-explosion (tTiad)- The data indicate competitive energetic materials. [ABSTRACT FROM AUTHOR]

Two new copper complexes, [Cu(phen)2F0X-7](phen)N03-4H20 and [Cu(phen)2F0X-7]Cl-3H20 (phen = 1,10-phenanthroline monohydrate; FOX-7 = l,l-diamino-2,2-dinitroethylene) were synthe-sized and structurally characterized. Single crystal X-ray diffraction shows that Cu(II) in the two complexes has similar five-coordinate structure, including four nitrogens from two phen and one nitrogen from FOX-7 anion. Thermal decomposition behaviors of the two complexes were studied with differential scanning calorimetry and thermogravimetry/differential thermo-gravimetry methods. The apparent activation energies and pre-exponential constants of the main exothermic decomposition reaction for the two complexes are 208.1 and 183.1 kj mol-1, 1022.99 and 1019.19 s-1, respectively. The self-accelerating decomposition temperature and critical tem-perature of thermal explosion for the two complexes are 152.64 and 162.17°C, 161.50 and 173.29°C, respectively. [ABSTRACT FROM AUTHOR]

1-(5-(Anthracen-9-yl)-3-(4-methoxyphenyl)-4,5-dihydropyrazol-1-yl)ethanonewas synthesized and crystallized to provide three types of crystalswith different fluorescent colors and host–guest structures.Crystal structure analysis reveals that this compound possesses twistedπ-conjugated structure and different degrees of distortion dependingon guest molecules in the three crystal structures. The anthracenefluorophore stacking modes are regulated from monomer arrangementto face-to-face π-stacked arrangement by means of the entrapmentof organic acid molecules in the lattice. The vibrational spectroscopy,thermal behaviors, diffuse reflectance absorption spectroscopy, solid-statefluorescence properties, and fluorescence quantum yields and lifetimesof the three types of crystals were investigated. Such propertiesare closely related to the fluorophore stacking modes and intermolecularelectronic interactions in crystals. The π-stacked geometriesof anthracene fluorophores are responsible for the red-shifted emissionsand longer fluorescence lifetimes. It indicates that the optical propertiesof organic materials could be modulated by entrapping different guestmolecules in lattice. [ABSTRACT FROM AUTHOR]

Abstract: The effect of growth temperature on the surface morphology and crystalline structure of InAs/GaSb type-II superlattices (SLs) grown on (100) GaSb substrates by metalorganic chemical vapor deposition (MOCVD) was investigated by in-situ reflectance measurement, atomic force microscopy, high-resolution x-ray diffraction and Raman scattering spectroscopy. All the data show that the structural properties of the SL samples are very sensitive to the growth temperatures. The optimal SL growth temperature in our MOCVD is 520°C. Only 20°C lower of the temperature resulted in rough surfaces from the beginning of SL epitaxy and 20°C higher resulted in the composition of the mixing interfaces far from expected and consequently deteriorated structure. Room temperature absorption from 2 to 8μm has been realized by our samples. [Copyright &y& Elsevier]

Two trinuclear 3,5-diamio-1,2,4-triazole(Hdatz)-derived nickel(II) compounds, [Ni3(Hdatz)6(H2O)6]Br6 · 4H2O (1) and [Ni3(Hdatz)6(datz)2(H2O)4]Cl4 · 6H2O (2), are reported. Structural analyses reveal that in 1 the six Hdatz ligands are bidentate N1, N2-bridging coordination. However, the X-ray diffraction analysis shows that in 2 there are eight triazole ligands, six of which are neutral and two deprotonated. Four neutral triazoles are N1, N2-bridging and two monodentate; the deprotonated triazoles (datz) are bidentate N1, N2-bridging. The coexistence of both neutral and anionic triazole ligands as well as different coordination modes in one compound is relatively rare. The difference in coordination modes is believed to be anion-controlled. Both compounds are additionally characterized by elemental analysis, IR, and UV-Vis spectroscopy. [ABSTRACT FROM PUBLISHER]

Eight alkaline and alkaline-earth compounds derived from 2,4-dinitroimidazole (2,4-HDNI) were synthesized and characterized by elemental analysis, FT-IR, and TG-DSC, of which K(2,4-DNI) (1), Rb(2,4-DNI)(2,4-HDNI)(H2O)2 (2), and Ba(2,4-DNI)2(H2O)4 (3) were characterized by single-crystal X-ray diffraction analysis. All the three compounds were crystallized from water, but 1 was an anhydrate. The coordination number in 1 and 3 is 10, but in 2 is 9. The 2,4-DNI adopts either η3, η2, or η1 coordination modes depending on the metal cation. In 3, there is an inversion center located on the metal. Only in 2 does water play an important role for the construction of the structure; in 3 it is a hydrogen bonding participant. TG-DSC analyses of 1 were also performed, and non-isothermal decomposition reaction kinetics were obtained. [ABSTRACT FROM AUTHOR]

Three neodymium compounds, Nd(4DNP)3(C2H5OH)3 (1), Nd(4DNPO)3 · 7H2O (2), and {[Nd(μ-ox)(4DNPO)(H2O)4] · 4H2O}n (3) (4HDNP, 3,5-dinitropyrid-4-one; 4HDNPO, 3,5-dinitropyrid-4-one-N-hydroxide; ox, oxalate), were synthesized and characterized by FT-IR, elemental analysis, thermogravimetry-differential scanning calorimetry (TG-DSC), and two of them by single-crystal X-ray diffraction analyses. The results revealed that in 1, the Nd(III) is surrounded by three chelating ligands and three ethanol solvent molecules. The structure of 3 could be described as 1-D chains in which Nd is bis-bidentately bridged by oxalates, together with a monodentate 3,5-dinitropyrid-4-onate N-oxide 4DNPO ligand and four water molecules as well as four uncoordinated water molecules in the crystal lattice. The origin of the oxalate anions in 3 is probably due to decomposition of the 4DNPO or its oxidation of other species. The TG-DTG (DTG, derivative thermogravimetry) and DSC analyses showed that 1 underwent a three-stage decomposition process. A kinetic equation for decomposition reaction of 2 was also obtained. The apparent activation energy (Ea) and pre-exponential factor (A) of the main decomposition reaction are 157.70 kJ mol-1 and 1011.97 s-1, respectively. The kinetic equation can thus be expressed as dα/dt = 1011.97(1 - α)e-1.90 × 104/T. [ABSTRACT FROM AUTHOR]

The remediation efficiency of the solidification/stabilization (s/s) method on soil contaminated with heavy metals may deteriorate when the treated soil is exposed to freezing–thawing (F–T) cycles. In this study, a series of laboratory tests were conducted to investigate the strength and microstructural characteristics of Zn-contaminated soil treated by cement-soda residue under cyclical F–T conditions. Test results showed that the stress–strain curves were able to be characterized by a strain softening model and the failure mode could be classified as brittle failure before subjecting to F–T cycles. After exposure to the F–T cycles, the stress–strain curves gradually began to resemble the hardening model, and the compressive strength decreased significantly. Unconfined compressive strength (UCS) of the specimens obtained the maximum value at Zn2+ concentration of 2000 mg/kg, regardless of their exposure to the F–T cycles; sample Zn0.2 was the most vulnerable. After being subjected to F–T cycles, micro-cracks formed in the specimens. These cracks would be enlarged by the continuous exposure to F–T cycles, which resulted in the reduction of strength. F–T cycles could significantly damage the crystalline structures of cement hydrates; the damage could also contribute to the deterioration of soil structure. Microstructural analysis results showed that the size of the samples' micro-pores decreased due to the migration of pore water during freezing, while the size of larger pores increased due to ice lens formation and expansion. • Freezing‐thawing (F‐T) cycles cause obvious deterioration in the UCS of the S/S treated Zn-contaminated soil. • The visible cracks are occasionally detectable after 6 F‐T cycles. • F‐T cycles significantly damage the crystalline structures of cement hydrates. • F‐T cycles result in the shrinkage of micro-pores and expansion of macro-pores. [ABSTRACT FROM AUTHOR]

A pair of stable chiral coordination compounds {[Zn (D -hpg) (bpe)]⋅(NO 3)⋅(C 2 H 6 O)} n 1-D , {[Zn (L -hpg) (bpe)]⋅(NO 3)⋅(C 2 H 6 O)} n 1-L (D -Hhpg = D -(−)-4-Hydroxyphenylglycine, L -Hhpg = L -(+)-4-Hydroxyphenylglycine, bpe = 1,2-bis(4-pyridyl)ethane) have been successfully synthesized. Their structures were determined by single-crystal X-ray diffraction analysis and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis and powder X-ray diffraction. Interestingly, they are 2D layer structures that consist of left- or right-handed helical chains, respectively. Circular dichroism and luminescent properties of compounds 1-D and 1-L were investigated at room temperature. Moreover, 1-D and 1-L show similar selectivity toward Cu2+ ions through luminescent quenching in aqueous solution. In addition, 1-D also displays an excellent recognition ability on detecting CH 3 OH. A pair of two-dimensional homochiral coordination compounds {[Zn (D-hpg) (bpe)]⋅ (NO3)⋅(C2H6O)}n 1-D and {[Zn (L-hpg) (bpe)]⋅(NO3)⋅(C2H6O)}n 1-L have been synthesized (D/L-Hhpg = D (−)/L (+)-4-Hydroxyphenylglycine, bpe = 1,2-bis (4-pyridyl)ethane). 1-D and 1-L show luminescent recognition towards Cu2+ ions. In addition, 1-D also displays an excellent recognition ability on detecting CH3OH. Image 1 • There are only a few articles were reported that coordination compounds prepared. • With D -(−)- and L -(+)-4-Hydroxyphenylglycine. • Compounds exhibit 2D layerd and helical structures. • Compounds 1-D and 1-L show luminescence selective recognition properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recyclable titania-supported iridium catalysts enabled the synthesis of benzimidazoles via hydrogen transfer at 80 oC. • Iridium catalysts supported on {010}/{101}-faceted anatase showed the unexpected excellent activity. • The catalysts were recyclable and acted heterogeneously without leaching of iridium species. • Highly-dispersed surface iridium species would be responsible for the excellent activity. Titania-supported iridium catalysts which enable the synthesis of benzimidazoles from 2-nitroaniline and primary alcohols under mild conditions have been developed. The iridium catalysts supported on {010}/{101}-faceted anatase (PA-135-3.5) showed the excellent activity in spite of their moderate surface areas, while there is a positive correlation between BET surface area and the activity of iridium catalysts. TEM analysis revealed the formation of small iridium nanoparticles (mean diameter; 1.0 nm) on PA-135-3.5, which would be one reason for the excellent catalytic activity. According to the XPS study, relatively high-valent iridium species would be responsible for the catalysis. Various primary alcohols bearing electron-withdrawing or electron-donating groups were applicable. The removal of the solid catalyst by the hot filtration completely stopped further progress of the reaction, indicating that the catalyst acted heterogeneously. The catalysts could be recycled, and there was no leaching of iridium species into the solution. [ABSTRACT FROM AUTHOR]