Crystal Structures and Luminescent Properties of Two Lanthanide(III) Complexes Featuring Double-Stranded Helical Chains of Based on 2-Sulfoterephthalate

Hydrothermal reaction of Eu³⁺ and Dy³⁺ salts with monosodium 2-sulfoterephthalate (NaH₂stp) gives two 2D lanthanide coordination polymers, [Ln(stp)(H₂O)₂] _n (Ln = Eu (1) and Dy (2)). Single-crystal X-ray diffraction of the complexes reveal that both 1 and 2 crystallize in the triclinic crystal system of Pī space group. For 1, each Eu³⁺ ion lies in a 9-coordinated slightly distorted tri-capped triangle pyramidal configuration. The stp ligands adopt a μ ₄-type link to the metal ions to form a 2D layer-like structure, of which there exist the left- and right-handed double-stranded helical chains. For 2, each Dy³⁺ ion is in a 8-coordinated distorted bi-capped triangle pyramidal geometry. The double-stranded helical chains in 2 differ from those in 1. The thermal stabilities of the two compounds are studied by TGA. The solid state photoluminescence of 1 and 2 are reported. The fluorescent decay curves of the ligand and compounds indicate that 1 has the lifetime of 286.7 μs, τ ₁ = 0.51 ns and τ ₂ = 3.07 ns for the ligand, and for 2, τ ₁ = 0.53 ns and τ ₂ = 2.71 ns.     

Theoretical study of the reactive intermediate Si2Me4[(η5-C5H4) Fe(CO)2] 2 2−

In two previous papers (Kinget al., J. Organomet. Chem. 19, 327, 1969; Pannellet al., Organometallics 9, 859, 1990), the synthesis and X-ray structure of the two tetramethyl disilyl complexes [(η⁵-C₅H₅) Fe(CO)₂]₂Si₂Me₄ (I) and Si₂Me₄[(η⁵-C₅H₄) Fe(CO)₂CH₃]₂ (II) were reported. ComplexII is obtained fromI [2]. However, attempts to form other derivatives fromI have generally failed. In the chemical process to getII fromI, an intermediate complex, Si₂Me₄[(η⁵-C₅H₄) Fe(CO)₂] ₂ ^2? (III), is probably formed. This is similar to complexII without the two methyl groups bonded to the Fe atoms. Therefore, a theoretical study that may shed some light on the intermediate structure, stability, and reactivity is justified. We have developed theoretical studies consisting of extended Huckel electronic structure calculations on the simulated intermediate geometry. The results obtained from these calculations suggest that it might be stable enough to form during reactions of complexI. The more reactive sites, which suggest reaction alternatives, are pointed out.     

A Series of Luminescent Lanthanide–Organic Complexes Constructed from In Situ Generated Dithiobenzoic Acid

Two types of lanthanide thiolato-carboxylate complexes, [Type I: [Yb(dtba) (Hdtba)] _n (1), Type II: [Ln(dtba)_1.5(biim)] _n (Ln = Pr (2a), Nd (2b), Sm (2c), Eu (2d), Gd (2e), Tb (2f), Dy (2g), H₂dtba = 2,2′-dithiodibenzoic acid, bimm = diimidazole)] have been obtained by hydrothermal method and characterized by the single-crystal X-ray diffraction, IR, 2D-COS IR, TG and the luminescence analysis. The H₂dtba ligand came from the in situ S–S function reaction of 2-mercaptobenzoic acid (H₂mba) under the hydrothermal condition. Complex 1 is a 2D bamboo-like sqr-topology layered structure, and the 3D (4, 4, 6)-connected supramolecular frameworks is produced by the hydrogen bonds of O–H···O. Complexes of type II (from 2a to 2g) are isostructural and they are assigned to 1D rope-like chains by introducing the chelating ligand of diimidazole. These 1D rope-like chains are further linked by N–H···O hydrogen bonds into a 3D supramolecular framework with CdSO₄-type topology. Photoluminescence studies reveal that complexes 2b, 2c, 2d, 2f, 2g exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.     

Synthesis and characterization of new poly(amide)s derived from bis(4-(4-aminophenoxy)phenyl)methylphenylsilane and bis(4-carboxyphenyl)R1R2 silane acids

This study describes the synthesis and characterization of a new diamine; bis(4-(4-aminophenoxy)phenyl)methylphenylsilane, which by reaction with bis(4-carboxyphenyl)R₁R₂ silane derivatives, and following the methodology of the direct polycondensation, allowed the preparation of three new poly(amide)s (PAs). These polymers contain two diphenylsilane (Ph–Si–Ph) and oxyether moieties in their repetitive unit. The reaction to obtain the diamine starting from the respective diphenol was developed in two steps. The first step consisted on obtaining the dinitro derivative, bis(4-(4-nitrophenoxy)phenyl)methylphenylsilane, with a yield of 83 %. Then, this compound was reduced by reaction with hydrazine and Pd-activated carbon, with a yield of 67 % in the diamine. Both compounds were characterized by spectroscopic techniques (FT-IR, ¹H, ¹³C and ²⁹Si NMR). The synthesis of the PAs (PA-I, PA-II and PA-III) presented a yield of 35–79 %, glass transition temperature between 136 and 149 °C and inherent viscosities in the range 0.08–0.16 g/dL. PA-I and PA-III presented a transmittance value (at 400 nm) of 91 and 87 %, respectively, while PA-II only reached a value of 70 %. All these results were analysed in accordance with structural details of each repetitive unit and were also compared with those obtained from poly(amides) series not containing flexible elements in their chains. The TGA analyses demonstrated that the new polymers still maintain a high thermal resistance, despite the incorporation of the flexible units.     

Organosoluble and thermally stable modified poly(ether-imide-urethane)s bearing benzoxazole or benzothiazole pendent groups: synthesis and characterization

Preparation of new types of modified poly(ether-imide-urethane)s, P _O a-c and P _S a-c, with good thermal stability and improved solubility was investigated. Two new bis(ether-azide)s bearing benzoxazole or benzothiazole pendent groups were synthesized by treating 2-[3,5-bis(4-trimellitimido-phenoxy)-phenyl]benzoxazole (1 _O ), or 2-[3,5-bis(4-trimellitimido-phenoxy)-phenyl]benzothiazole (1 _S ) with ethyl chloroformate in the presence of triethylamine, and subsequent by a nucleophilic reaction with sodium azide, respectively. Two series of modified polymers with moderate inherent viscosities between 0.21 and 0.32 dL g^?1 were prepared from bis(ether-azide)s 2 _O and 2 _S with several aromatic diols in dry toluene under refluxing in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO, triethylenediamine) as a catalyst. The polycondensation reaction readily proceeded in desirable yields as one-pot reactions starting from 2 _O to 2 _S without the separate synthesis of the corresponding bis(ether-isocyanate)s. In addition, the corresponding unsubstituted poly(ether-imide-urethane)s, P _R a-c, were prepared under identical experimental conditions for comparative purposes. All of the resulted polymers were thoroughly characterized by spectroscopic methods and thermogravimetry. The solubilities of modified polymer in common organic solvents as well as their thermal stability were enhanced compared to these of the corresponding unmodified polymers. The glass transition temperature, 10 % weight loss temperature and char yields at 800 °C were, respectively, 13–28 °C, 19–32 °C and 3–7 % higher than those of the unmodified polymers.     

From 5-Hydroxymethylfurfural (HMF) to Polymer Precursors: Catalyst Screening Studies on the Conversion of 1,2,6-hexanetriol to 1,6-hexanediol

1,6-hexanediol (1) is an important polymer precursor for the polyester industry. In this paper, exploratory catalyst screening studies on the synthesis of 1 from 1,2,6-hexanetriol (2) are described via two different routes. The latter is available by a two-step procedure from 5-hydroxymethylfurfural (HMF, 3), a promising bio-based platform chemical. In the first approach, the direct catalytic hydrodeoxygenation of 2 to 1 with heterogeneous catalysts and molecular hydrogen was explored. Best results were obtained using a Rh?CReO_x/SiO₂ catalyst in water (180?°C, 80?bar H₂, 20?h reaction time), leading to full conversion of 2 and 73?% selectivity to 1, the main byproduct being 1,5-hexanediol (4). In a second approach, 2 was first converted to tetrahydropyran-2-methanol (2-THPM, 5) in quantitative yield using triflic acid as catalyst (125?°C, 30?min). Various catalysts were explored for the subsequent ring opening/hydrodeoxygenation of 5 to 1 using a hydrogenation protocol and the best results were obtained with a Rh?CReO_x/SiO₂ catalyst, viz. 96?% selectivity to 1 at 26?% conversion (120?°C, 80?bar H₂, 20?h).     

Syntheses and Characterization of Two New M(II)-5,5′-dimethyl-2,2′-bipyridine (M = Cd and Pb) Coordination Polymers and Study of Their Thermal and Electrochemical Properties

Two new cadmium(II) and lead(II)-thiocyanato coordination polymers with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dm-2,2′-bpy) as chelating ligands were synthesized and characterized by elemental analysis, IR and ¹H NMR spectroscopy and by X-ray crystallography. Thermal and electrochemical properties were also studied as well. These complexes have formed formula [Cd(5,5′-dm-2,2′-bpy)(NCS)₂]_n (1) and [Pb(5,5′-dm-2,2′-bpy)(CH₃COO)(NCS)]_n (2). The coordination numbers of Cd^II in 1 and Pb^II in 2 are six (CdN₄S₂) and seven (PbN₃O₃S₂), respectively. In 2, “stereo-chemically active” electron lone pairs and the coordination spheres were hemidirected. Bridging properties of thiocyanato anions in 1 and 2 created one- and two-dimensional coordination polymers, respectively. The supramolecular features in these complexes were guided and controlled by weak directional intermolecular interactions.     

Positions and Stereochemistry of Methyl Branches in the Novel Sex Pheromone Components Produced by a Lichen Moth, Lyclene dharma dharma

Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce three sex pheromone components (I–III), for which we assigned the following novel chemical structures; 6-methyl-2-octadecanone (1) for I, 14-methyl-2-octadecanone (2) for II, and 6,14-dimethyl-2-octadecanone (3) for III. In the Iriomote Islands where the insects were collected, a lure including racemic 1 and 2 attracted the male moths without mixing 3. In this study for further confirmation of the plane structures, the positional isomers with a methyl branch at the 4-, 5-, 7-, 13-, or 15-position (4–8, respectively) were synthesized. The GC-MS analyses revealed that natural components I and II were best fitted with those of 1 and 2, respectively, among the methyl-2-octadecanones examined, indicating the usefulness of this analytical instrument and authentic standards for the determination of the positions of methyl branches. In field trapping tests, 4–8 could not substitute for 1 or 2, nor did these compounds inhibit the active binary lure of 1 and 2, indicating that the males strictly recognized the 2-ketones with a methyl branch at the 6- or 14-positions. Next, the absolute configurations of I and II were determined by HPLC with a normal-phased chiral column (Chiralpak AD-H), which could separate the enantiomers of both 1 and 2. The chiral HPLC analysis of a crude pheromone extract indicated that the females exclusively produced (S)-1 and (S)-2. Furthermore, a field evaluation of each enantiomer revealed that (S)-1 and (S)-2 were bioactive but (R)-1 and (R)-2 were not.     

Uranyl Coordination Polymers Incorporating η5-Cyclopentadienyliron-Functionalized η6-Phthalate Metalloligands: Syntheses,Structures and Photophysical Properties

The reaction of two η⁵-cyclopentadienyliron(II)-functionalized terephthalate and phthalate metalloligands, namely [(η⁵-C₅H₅)Fe^II(η⁶-1,4-HO₂CC₆H₄CO₂H)][(η⁵-C₅H₅)Fe^II(η⁶-1,4-HO₂CC₆H₄CO₂)][PF₆] and [(η⁵-C₅H₅)Fe^II(η⁶-1,2-HO₂CC₆H₄CO₂H)][(η⁵-C₅H₅)Fe^II(η⁶-1,2-HO₂CC₆H₄CO₂)][PF₆]—hereafter [H₂ CpFeTP][HCpFeTP][PF₆] and [H₂ CpFeP][HCpFeP][PF₆], respectively—with [UO₂(NO₃)₂]·6H₂O under hydrothermal conditions yielded four new coordination polymers; (1) [(UO₂)F(HCpFeTP)(PO₄H₂)]·2H₂O, (2) [(UO₂)₂(CpFeTP)₄]·5H₂O, (3) [(UO₂)₂F₃(H₂O)(CpFeP)], and (4) [H₂ CpFeP][UO₂F₃]. The use of metalloligands has proven to be a viable route towards the incorporation of a secondary metal center into uranyl bearing materials. Depending upon the protonation state, the iron sandwich metalloligands may vary from zwitterionic neutral or monoanionic coordinating species as observed in compounds 1–3, or a positively charged species that hydrogen bonds with anionic [UO₂F₃]^? chains as observed in 4. Further, the hydrolysis of the charge balancing PF₆ ^? anion increases the diversity of UO₂ ²⁺ coordinating species by contributing both F^? and PO₄ ^3? anions (1, 3, 4). The luminescent properties of 1–4 were also studied and revealed the absence of uranyl emission, suggestive of a possible energy transfer from the uranyl cation to the iron(II) metal center.     

New host–guest supramolecular coordination polymers based on [(Me3Sn)3Fe(CN)6]n with alkali metal iodides and their applications as electrode materials in batteries

The metal iodides reduce partially the host coordination polymer of the type $ ^{ 3}_{\infty } \left[ {\left( {{\text{Me}}_{ 3} {\text{Sn}}} \right)_{ 3} {\text{Fe}}\left( {\text{CN}} \right)_{ 6} } \right] $ , I, to give new host–guest supramolecular coordination polymers (SCP). The physical and chemical characteristics of the new products were studied by elemental analyses, X-ray powder diffraction, IR, UV/Vis, and solid state NMR spectra. The host–guest SCP are [M_x(Me₃Sn)₃Fe_(1–x)^IIIFe _x ^II (CN)₆]_n M = Li⁺·2H₂O, 1; Li⁺, 2; Na⁺, 3; K⁺, 4; Cu⁺, 5, [Li(Me₃Sn)₃Fe^II(CN)₆]_n, 6 and [(LiDEE)_0.9(Me₃Sn)₃Fe _o.1 ^III Fe _o.9 ^II (CN)₆]_n, 7. The stoichiometry and nature of the guest depend on the type of the metal iodide and the reaction conditions. The polymeric nature of these SCP is due to the presence of trigonal bipyramidal configured structure which bridges between the single d-transition metal ions. The host–guest SCP containing the Li ions have been tested as electrodes to construct four different lithium-ion batteries.     

Syntheses, Structures and Properties of Two 2D Transition Metal Coordination Polymers Based on Oxalate and Two Types of N-donor Auxiliary Ligands

Two new two-dimensional (2D) metal–organic coordination polymers [Co(ox)(bbbm)]·H₂O (1) and [Cu(ox)(bppdca)]·2H₂O (2) (H₂ox = oxalic acid, bbbm = 1,1-(1,4-butanediyl)bis-1H-benzimidazole and bppdca = N,N′-bis(pyridin-3-yl)-2,6-pyridinedicarboxamide) were synthesized under hydrothermal conditions and structurally characterized. Both 1 and 2 exhibit a 2D four-connected network formed by the Co^II/Cu^II ions as four-connected nodes; and, the ox anions and bbbm/bppdca ligands as linkers with a (4⁴.6²) topology as determined by single crystal X-ray diffraction. In addition, the thermal stability, electrochemical and luminescent properties for 1 and 2 were investigated.     

Structure and Properties of Self-Assembled Ternary Adducts K3[Cu(CN)4], Trimethyl Tin Chloride and 4-Methylpyrimidine

The reaction of K₃[Cu(CN)₄], Me₃SnCl and 4-methylpyrimidine (mpym) at room temperature affords the 3D-octameric _∞ ³ [Cu₈(CN)₈(mpym)₄], I, in water/acetonitrile and the 3D-host–guest _∞ ³ [Cu₈(CN)₈(mpym)₄ dioxane], II. The X-ray single crystal diffraction of I reveals the formation of homometallic octameric building blocks consisting of three fused 11 membered rings. The 3D-network structure of the supramolecular coordination polymer (SCP), I, consists of two crossing sets of parallel corrugated interpenetrating CuCN chains, which are connected by mpym, hydrogen bonds, π–π stacking and cuprophilic interactions. Species II is isostructural with I as indicated by X-ray powder diffraction and spectroscopic measurements.     

Hydrothermal Syntheses and Crystal Structures of Three Zn(II) Coordination Compounds Constructed with 3,5-Pyrazoledicarboxylic Acid

Three novel metal–organic coordination compounds, [Zn(Hdcp)(H₂O)₄]·1.5H₂O (1), [Zn(Hdcp)(H₂O)₂]_∞ (2) and [Zn₃(dcp)₂(H₂O)₅]_∞ (3) with the ligand 3,5-pyrazoledicarboxylic acid were prepared by the hydrothermal method. The complexes were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Compound 1 is a mononuclear molecule that is linked into a 3D supramolecular framework via N–H···O and O–H···O hydrogen bonds. In 2, two types of carboxylic bridges were found between Zn^II ions to form a 1D double-chain. The 1D chains were further construct into a 3D structure by hydrogen bonds. Trinuclear 3 consists of 1D bi-infinite parallelogram chains of [Zn₃(dcp)₂(H₂O)₃] trimers. In the basic trinuclear unit a further bridging mode of the ligand is seen where two dcp^3? ligands chelate three Zn^II ions by utilizing five donors of the dcp^3? ligand. The photoluminescent properties of 1, 2 and 3 were investigated.     

Synthesis,characterization, and platinum-catalyzed cross-linking of 1,4-bis(1-methyl-1-silacyclobutyl) benzene,co-oligo(1-silacyclobut-1-ylidene-1,4-phenylene), and co-oligo(1-silacyclobut-1-ylidene-4,4′-diphenylene)

1,4-bis(1-Methyl-1-silacyclobutyl)benzene (I) has been prepared by the reaction of 1-chloro-1-methyl-1-silacyclobutane with the di-Grignard reagent prepared fromp-dibromobenzene. In a similar manner, co-oligo(1-silacyclobut-1-ylidene-1,4-phenylene) (II) and co-oligo(1-silacyclobut-1-ylidene-4,4′-biphenylene) (III) have been prepared by condensation oligomerization between 1,1-dichloro-1-silacyclobutane and the di-Grignard reagents prepared fromp-dibromobenzene and 4,4′-dibromobiphenyl, respectively. These have been characterized by¹H,¹³C, and²⁹Si NMR as well as FT-IR and UV spectroscopy. The molecular weight distributions of these co-oligomers have been determined by GPC. Their thermal stabilities have been evaluated by TGA. Thermal degradation of these co-oligomers in nitrogen gives high (60%) char yields. The stability of these chars in air has been determined. TheT _g's of these co-oligomers have been measured by DSC. Platinum-catalyzed ring opening of the silacyclobutane rings ofI,II, andIII cross-links these to thermoset materials. The bending moduli (logE′), tan δ, andT _g's of these materials have been determined by DMTA. The dielectric constant and dissipation factor of cross-linkedII are reported.     

Electroactive polymer actuator from highly doped permethylpolyazine dispersed in ethylene propylene diene elastomer

Structural, electronic, and optical properties of a series of ??-conjugated thiophene oligomers P1-P3 and CF ₃ P1-CF ₃ P3 have been theoretically investigated. P1-P3 contain the 2- (trifluoromethyl) thieno [3, 4-b] thiophene moiety as the centre and 1?C3 repeating thiophene units adjacent to its two sides respectively, while their corresponding derivatives CF ₃ P1-CF ₃ P3 with the CF₃ as end-caps. The geometric structures of the oligomers in the ground and excited state were optimized by PBE1PBE and CIS methods with 6?C31G (d) basis sets, respectively. All the oligomers exhibit zigzag arrangements. The absorptions and emissions were calculated by the time-dependent density functional theory method (TD-PBE1PBE). The lowest-lying absorptions of all the oligomers can be characterized as ??-??^* electron transition. For each series of oligomers, there is a progressive lowering in HOMO-LUMO gap with the increase of the repeating unit, being consistent with the red-shifted trend in the lowest-lying absorption and fluorescence from P1 to P3 and CF ₃ P1 to CF ₃ P3. To compare the P- and corresponding CF ₃ P-oligomers, the end-cap CF₃ group causes the slight blue shifts in absorption and emission spectra. The ionization potentials (IP_S), electron affinities (EAs), and reorganization energies (??) as well as the hole/electron extraction energies (HEP/EEP) of the oligomers were explored and those of the corresponding polymer were obtained by extrapolation method. The IP and HEP of P-polymer are lower than those of CF ₃ P-polymer, indicating that the P-polymer is more suitable for hole transport than CF ₃ P-polymer, while the higher EA and EEP for CF ₃ P-polymer suggest the better electron transfer property. For CF₃ end-caps, the CF ₃ P-polymer exhibits the equal reorganization energy between electron and hole, which is a precondition for the charge transfer balance.     

Simultaneous Growing of Two New Cd(II) Metal–Organic Frameworks with 2,6-Naphthalendicarboxylic Acid as New Precursors for Cadmium(II) Oxide Nanoparticles: Thermal, Topology and Structural Studies

Crystal structure and thermal stability of two new 3D Cd(II) metal–organic frameworks (MOF) containing 2,6-naphthalenedicarboxylate, [Cd(NDC)(DMF)], 1, and [Cd₃(NDC)₄], 2 (H₂NDC = 2,6-naphthalenedicarboxylic acid; DMF = N,N-dimethylformamide) have been studied. These two MOFs grow simultaneously within the same solution to give multiple crystals that are due to the general lability of Cd(II) complexes. Structure 1 shows a 3D neutral metal–organic framework with PtS topology and crystallizes in the triclinic system, space group P-1 (No. 2), whilst 2 crystallizes in the orthorhombic system, space group Fdd2 (No. 43) with body-centered cubic bcu-(4²⁴.6⁴) topology. The elongated nature of NDC results in large cavities in both compounds; however, the pores are filled by coordinated DMF molecules in 1. The thermal stability of 1 and 2 were studied by thermogravimetry and show stability to 400 °C for 1 and continuous weight loss for 2. CdO nanoparticles were prepared by direct calcination of 1 and 2 at 600 °C. The CdO nanoparticles were characterized by X-ray powder diffraction and its morphology were studied by scanning electron microscopy. The results show that the CdO is pure and has a uniform morphology.     

Influence of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand on the properties of fluorine containing polymers

The catalytic performance of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand in the ring opening metathesis polymerization (ROMP) of fluorine containing monomers, exo-N-4-fluorophenyl-7-oxanorbornene-5,6-dicarboximide (FPhONDI) and exo-N-4-fluorophenyl-norbornene-5,6-dicarboximide (FPhNDI) was investigated. Pure monomers were subjected to ROMP with RuCl₂(PCy₃)₂(CHPh) (I), RuCl₂(PCy₃)(H₂IMes)(CHPh) (II), RuCl₂(3-Br-py)₂(PCy₃)(CHPh) (III) and RuCl₂(3-Br-py)₂(H₂IMes)(CHPh) (IV). The polymers were fully characterized using NMR, DSC, SEM and GPC. Catalysts I–IV displayed significant ROMP activity, allowing for the synthesis of the corresponding polymers with polydispersity indices (PDIs) in the range of 1.4–4.0. High molecular weight polymers (Mw up to 4.95 x10⁵) were prepared in yields up to 90 %, depending on the initiator and monomer used.     

Structural, Theoretical and Multinuclear NMR Study of a New Polymeric Mercury(II) Complex with an Ambidentate Phosphorus Ylide

The reactions of phosphorus ylides of the type Ph₃P=C(H)C(O)R [R = 2,4-dichlorophenyl (L ¹ ) and 4-isopropylphenyl (L ² )] with HgX₂ [X = Cl (1, 4), Br (2, 5) and I (3, 6)] salts using methanol as a solvent are reported. Single crystal X-ray analysis carried out on L ¹ , 2 and 3 and reveals the presence of a novel polymeric structure for 2 and a centrosymmeteric dimeric structure for 3. The complexes have been studied by elemental analyses, IR, ¹H and ³¹P NMR spectroscopy. On the basis of DFT calculations, the formation of [Hg₂Br₆]^2? anions in 2 has a key role in the formation of the polymeric structure; and, the formation of [Hg₂L₂I₄] molecule thermodynamically is about 25 kcal/mol more favorable than the corresponding [Hg₂L₂Br₄] molecule.     

Polymerization of propylene catalyzed by α-diimine nickel complexes/methylaluminoxane: catalytic behavior and polymer properties

α-Diimine nickel dibromide complexes of dibromo[N,N’-bis(2,6-diisopropylphenyl)-2,3-butanediimine]nickel(II) (A) and dibromo[N,N’-(phenanthrene-9,10-diylidene)bis(2,6-diisopropylaniline)]nickel(II) (B) were synthesized under controlled conditions. The catalysts A, B and mixed of 1:1 weight ratio of them (C) were activated by methylaluminoxane and were used for propylene polymerization in a semi-batch reactor. In study of the catalytic systems behavior, activities, glass transition temperature (T _g) and viscosity average molecular weight (M _v) values related to the catalyst C were between those related to the catalysts A and B under same conditions. The highest and the lowest molecular weights of the obtained polymers were produced by the catalysts B and A which were about 80,000 and 70,000 (g/mol) under same conditions, respectively. The T _g of polypropylenes produced by the catalysts was about ?34 °C. The resulting polymers had similar behavior with ethylene-propylene copolymer which it could be due to formation of ethylene-type units in the polymer chain.     

Synthesis of novel calix[6]-1,4-crown-based netty polymer and its excellent adsorption capabilities for aniline derivatives

By introducing four ester groups on p-tert-butylcalix[6]-1,4-crown-4 and then ammonolysis with ethanolamine, p-tert-butylcalix[6]-1,4-crown-4 amido derivative with four terminal hydroxyl groups (4) was obtained in good yield. Further by reacting compound 4 with 1,1,1-tris(tosylatemethyl)propane (6) in NaH/THF system, the novel netty calix[6]-1,4-crown-based polymer 7 was prepared in ??4+3?? condensation mode. The structure of polymer 7 was confirmed by elemental analysis, IR and ¹H NMR spectra. The loose pores and cross-linked netty architecture were observed for polymer 7 in its SEM images. The M _n of polymer 7 was 39,816 which indicated an average of approximately 23 calixarene units in each polymer molecule. Polymer 7 exhibited outstanding adsorption abilities for series of aniline derivatives (aniline, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-nitroaniline, m-nitroaniline and p-nitroaniline). The adsorption percentages for these aniline derivatives were above 90?%. The saturation adsorption capacities for aniline and p-nitroaniline were as high as 2.30 and 2.22?mmol/g, respectively. The adsorption abilities of polymer 7 kept stable at pH 6?C10 and it could be re-used after desorption of 10?% HCl. The high adsorption abilities of polymer 7 for aniline derivatives were not just because of ?ШC?? stack action of the phenyl groups and the hydrogen bond action, but also due to the stable conformation of calix[6]arene skeleton and big cavity, which were favorable for adsorption of aniline derivatives.