Rigid rod polymers with flexible side chains. X. Thermotropic mesophases from aromatic stiff-chain polyamides bearing n-alkoxy side chains

The synthesis of stiff-chain poly(1,4-phenylene terephthalamide)s substituted by two as well as by four flexible side chains per repeating unit is described. The solubility of the materials bearing only two side chains is still very low. Appending of four side chains leads to polyamides which dissolve in common organic solvents. All polyamides reported herein form layered structures in the solid state as well as in the mesophase. Polyamides with two side chains have a very weak tendency for crystallization and do not exhibit a transition to the isotropic state even for the longest side chains. Polyamides with four side chains show three reversible thermal transitions: a disordering transition of the side chains, a transition to a layered, smectic-like mesophase, and finally the transition to an isotropic melt. It is shown that the phase behavior of these materials is mainly governed by the strong segregation of main- and side-chains which can be compared best to the microphase separation in block copolymers. © 1993 John Wiley & Sons, Inc.     

Hydrothermal synthesis of two copper helical coordination polymers with acentric three-dimensional framework constructing from mixed pyridine carboxylates

Two copper helical coordination polymers, [Cu(2-pc)(3-pc)]_n1 and [Cu(2-pc)(4-pc)]_n2 (2-pc=2-pyridine carboxylate, 3-pc=3-pyridine carboxylate, 4-pc=4-pyridine carboxylate) have been hydrothermally synthesized directly from pyridine carboxylic acids and copper nitrate. The crystal structure were determined by single-crystal X-ray diffraction with the following data: compound 1, orthorhombic, P2₁2₁2₁, a=6.591(3) Å, b=8.692(5) Å, c=20.548(9) Å, V=1177.2(9) Å³, Z=4; compound 2, orthorhombic, Pna2₁, a=21.160(10) Å, b=9.095(5) Å, c=6.401(3) Å, V=1231.9(11) Å³, Z=4. The acentric three-dimensional (3D) framework of 1 is constructed from right-handed helical Cu(2-pc) chains and left-handed Cu(3-pc) helices. As for 2, Cu(2-pc) helical chains, in which left- and right-handed helices are coexisting, and Cu(4-pc) zigzag chains combined together to form acentric 3D architecture of 2 as well. Additionally, besides general spectral characterization, we first introduce generalized 2D correlation spectroscopy to explore the coordination polymers and ascertain the stretching vibration location of carboxylate groups of compounds 1 and 2.     

Complexes of nickel(II) carboxylates with pyridine and cyclam: crystal structures,mesomorphisms, and thermoelectrical properties

Nickel(II) carboxylates [Ni(CH₃(CH₂)₁₄COO)₂(H₂O)₂] (1) and [Ni(C₆H₅COO)₂(H₂O)₂] (2) were obtained from reactions of NiCl₂·6H₂O with CH₃(CH₂)₁₄COONa and C₆H₅COONa, respectively. Complex 1 reacted with pyridine (pyr) to form [Ni(CH₃(CH₂)₁₄COO)₂(pyr)₂(H₂O)₂] (3) and [Ni₂(μ₂-H₂O)(CH₃(CH₂)₁₄COO)₄(pyr)₄] (4) in the same reaction mixture, and reacted with cyclam to form an ionic complex, [Ni(CH₃(CH₂)₁₄COO)(cyclam)(H₂O)]CH₃(CH₂)₁₄COO·4H₂O (5). In contrast, 2 reacted with cyclam to form [Ni(C₆H₅COO)₂(cyclam)] (6). Finally, 6 reacted with p-(hexadecyloxy)pyridine (L) to form an ionic complex, [Ni(cyclam)(L)₂](C₆H₅COO)₂ (7). Complexes 3–6 were single crystals. All complexes have octahedral Ni(II) center(s) and were magnetic. Complexes with cyclam as co-ligand were more thermally stable than those with pyridine and its derivative, L. Complexes 3 and 4 were mesomorphic after partial loss of water and/or pyridine ligands on heating. The ionic complexes 5 and 7 were not mesomorphic, but showed good thermoelectrical behavior with negative S_e values in CHCl₃ (?0.28 mV K^?1 for 5; -0.39 mV K^?1 for 7) and positive S_e values in C₂H₅OH (+0.25 mV K^?1 for 5; +0.20 mV K^?1 for 7).     

The Crystal Structures of two Linearly Polymeric Copper(II) Complexes of 2, 2′‐Bipyridine with threefold Glycolato and Oxalato Bridges

The complex [Cu(HGLYO)₂(bipy)] ( I ) and two new copper(II) coordination polymers with the formulas {[Cu(GLYO)_1‐x(ox)_x(bipy)]·2.5H₂O}_n [GLYO = glycolato dianion, ox = oxalato dianion, bipy = 2, 2′‐bipyridine, x = 0.56 (in II ) or 0.71 (in III )] were synthesized using copper(II) glycolate as starting material and were characterized by IR, UV‐Vis and EPR spectrometry, by magnetic measurements ( II and III ), and by single‐crystal X‐ray diffractometry. Both II and III crystallized as one‐dimensional polymers composed of Cu₂O₂‐centred dimers with a Cu‐Cu distance of 3.282(1)Å (mean of II and III ) that are linked by Cu₂(OCO)₂ rings with a Cu‐Cu distance of 5.237(1)Å (mean of II and III ), both dianions acting as (μ‐1, 1, 2, 3) three‐way bridges connecting the two copper atoms of one dimer with one copper atom of a neighbouring dimer. Each copper atom is coordinated tetragonally in a CuN₂O₄ chromophore. In the mononuclear complex I the copper atom has a tetragonally distorted octahedral environment.     

A domino desulfitative coupling and decarboxylative coupling of 3, 4-dihydropyrimidine-2-thiones with copper(I) carboxylates

A novel and general carbon-nitrogen and carbon-carbon cross-coupling reaction between 3,4-dihydropyrimidine-2-thiones and copper(I) carboxylates were performed in the presence of palladium acetate. The copper(I) carboxylates act not only as desulfurative reagents but also as sources of carbon nucleophiles. A wide array of highly substituted and functionalized pyrimidines scaffolds were synthesized in good yields.     

Synthesis, structure and optical limiting effect of a novel inorganic-organic hybrid polymer containing mixed chains of copper(I)/iodine

In this paper, treatment of N-ethyl-benzo[f]quinolium (ebq) iodide and CuI with excess KI afforded an unusual coordination polymer [(ebq)₂(Cu₃I₄)(CuI₂)]_n (1). 1 crystallizes in tetragonal system, space group P4(2)bc with cell parameters of , , , Z=8, , R₁=0.0447 and wR₂=0.0974. A highly interesting feature of 1 is its presence of mixed types of chains [ and chain] in one crystal lattice based on supramolecular self-assembly directed by cations. The infinite chains and in 1 could be described as the edge-sharing arrangement of CuI₄ tetrahedron. Furthermore, IR, EA, UV-Vis, thermal analysis and optical limiting measurements were adopted to characterize polymer 1. The optical limiting experiment shows that the present polymer exhibits a large optical limiting capacity.     

Modular synthesis of bis(monoacylglycero)phosphate for convenient access to analogues bearing hydrocarbon and perdeuterated acyl chains of varying length

Bis(monoacylglycero)phosphate is an important phospholipid that controls the structure of late endosomes as well as biological activities that occur there. The study of this lipid is complicated by the fact that acyl migrations are known to generate different regioisomers. Herein, we describe a modular synthesis of 3,3′-BMP derivatives that allows for the incorporation of a range of different acyl chains at a late stage. This approach was exploited to produce eight BMP analogues bearing normal saturated and perdeuterated acyl chains of varying length.     

Reaction of MeO2C(H)C=C=C(H)CO2Me with Ru3(CO)12. New diruthenium complexes with bridging carboxylate-substituted allene ligands

The reaction of Ru₃(CO)₁₂ with MeO₂C(H)C=C=C(H)CO₂ Me has yielded two isomeric productsanti-Ru₂(CO)₆[μ-η ³-η ¹-MeO₂C(H)CCC(H)CO₂Me],1 in 70% yield andsyn-Ru₂(CO)₆[μ-η ³-η ¹-MeO₂C(H)CCC(H)CO₂Me],2 in 5% yield. Both compounds were characterized by single crystal X-ray diffraction analysis. Both products are diruthenium complexes with bridging di(carboxylate)allene ligands in which the oxygen atom of the carbonyl group of one of the carboxylate groupings is coordinated to one of the metal atoms. Compound1 isomerizes partially to2 at 68°C. Crystal Data for1: space group=P2₁/n,a=11.131(1) Å,b=10.228(2) Å,c=15.978(2) Å,β=102.01(1)°,Z=4, 1653 reflections,R=0.025; for2: space group=P $\bar 1$ ,a=9.340(1) Å,b=14.925(4) Å,c=6.778(2) Å,α=99-02(2)°,β=104 62(2)°,γ=94.58(2)°,Z=2, 1857 reflections,R=0.027.     

The X‐ray Single Crystal Structures of an Acid‐functionalized Bis(2‐picolyl)amine (bpa) Ligand with Palladium(II) and Zinc(II) Display Different Intermoleclar Interactions around the Common (H2O)2(anion)2 Motif

This work reports structural investigations on two metal complexes of the functionalized (p‐carboxylatobenzyl)‐bis(2‐picolyl)amine ligand 1 (HL). The complex {[HLPdCl]Cl × H₂O}₂ ( 2_Pd ) has a square‐planar coordination around the Pd ion. It forms discrete dimers by intermolecular hydrogen bonding involving the protonated ligand HL. The coordination around the Zn²⁺ ion in {[(H₂O)LZn]CF₃SO₃ × 2 H₂O}_∞ ( 3_Zn ) is best described as distorted trigonal‐bipyramidal. The N₃O₂ ligand sphere is composed of three nitrogen atoms from the bpa ligand, one water molecule, and a carboxylate oxygen atom from a neighbouring molecule, thus forming infinite chains along the crystallographic a axis. Further intermolecular interactions are based on the same (H₂O)₂(anion)₂ motif as for 2_Pd , but whereas the former forms discrete dimers, 3_Zn forms a more complicated two‐dimensional coordination polymer with additional intermolecular hydrogen bonds.     

Syntheses,crystal structures and electron paramagnetic resonance studies of Co- and Mn-coordination polymers with the twisted ligand di(4-pyridyl)disulfide in double bridge fashion

Four coordination polymers, {[Co₂(4-DPSS)₄(DMF)₄](ClO₄)₄}_n (1), {[Mn₂(4-DPSS)₄(DMF)₄](ClO₄)₄}_n (2), {[Co(4-DPSS)₂(H₂O)(NO₃)]NO₃·3H₂O}_n (3) and [Co(4-DPSS)₂(NCS)₂]_n (4) have been synthesized to study the reactivity of cobalt(II) and manganese(II) salts (perchlorate, thiocyanate and nitrate) with the flexible ligand di(4-pyridyl)disulfide (4-DPSS). These compounds have repeated rhomboidal structures in which the di(4-pyridyl)disulfide ligands coordinate the metal centers in a double bridged fashion. Each double chain and the metallocycle cavities are chiral and contain either the M- or the P-enantiomeric forms of 4-DPSS and are independent on recrystallization solvents or the metallic precursors. The crystal packing of these coordination polymers reveals that, in all cases, weak interactions such as classical and non-classical hydrogen bonds, as well as S?S interactions, connect the polymeric chains to increase the dimensionality of the network. Low temperature electron paramagnetic resonance (EPR) measurements on powdered samples show that the transition-metal ions, Co (II) and Mn (II) ions, are in the high spin states S = 3/2 and 5/2, respectively, and adopt octahedral geometry in case of compounds 1, 2 and 3, and rhombic environment in case of 4.     

Structural chemistry of mononuclear, tetranuclear and hexanuclear organotin(IV) carboxylates from the reaction of di-n-butyltin oxide or diphenyltin oxide with rhodanine-N-acetic acid

Three new organotin(IV) carboxylates, {[n-Bu₂Sn(O₂CC₄H₄NOS₂)]₂O}₂ (1), n-Bu₂Sn(O₂CC₄H₄NOS₂)₂ (2) and [PhSn(O)O₂CC₄H₄NOS₂]₆ · 3H₂O (3) were synthesized by the reaction of di-n-butyltin/diphenyltin oxide and rhodanine-N-acetic acid. The complexes 1-3 are characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR and X-ray crystallography diffraction analyses. The complex 1 has a tetranuclear structure based on a planar four-membered Sn₂O₂ ring, while complex 2 is a hexa-coordinated monomer. As for complex 3, it adopts the hexameric drum-shaped structure. The supramolecular structure of 1 has been found to consist of one-dimensional molecular chain built up by intermolecular non-bonded S?O interactions. The salient feature of the supramolecular structure of complex 2 is that of a one-dimensional polymer, in which intermolecular Sn?O, S?O and S?S interactions are recognized.     

Syntheses, structures and magnetic properties of five iron(II) coordination polymers with flexible bis(imidazole) and bis(triazole) ligands

Five iron(II) coordination polymers, {[Fe(bte)₂(NCS)₂][Fe(bte)(H₂O)₂(NCS)₂]}_n (1), [Fe(bime)(NCS)₂]_n (2), [Fe(bime)(dca)₂]_n (3), [Fe(bime)₂(N₃)₂]_n (4) and [Fe(btb)₂(NCS)₂]_n (5), were synthesized using the flexible ligands 1,2-bis(1,2,4-triazol-1-yl)ethane (bte), 1,2-bis(imidazol-1-yl)ethane (bime) and 1,4-bis(1,2,4-triazol-1-yl)butane (btb), together with NCS⁻, dicyanamide (dca) and N₃⁻. The compound 1 contains two kinds of motifs (double chain and single chain) and forms a three-dimensional hydrogen bonded network; 2 and 3 contain one-dimensional triple chains; and 4 and 5 form two-dimensional (4, 4) networks. The coordination anions (NCS⁻, dca and N₃⁻) and the structural characteristics of the ligands (bte, bime and btb) play an important role in the assembly of the topologies. Magnetic studies reveal that 1-5 remain in the high-spin state over the whole temperature range 2-300 K and no detectable spin-crossover is observed.     

Synthesis and properties of comb polymers with semirigid mesogen‐jacketed polymers as side chains

A series of novel comb polymers, poly{2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene}‐g‐polystyrene (PMPCS‐g‐PS), with mesogen‐jacketed rigid side chains were synthesized by the “grafting onto” method from α‐yne‐terminated PMPCS (side chain) and poly(vinylbenzyl azide) (backbone) by Cu(I)‐catalyzed 1,3‐dipolar cycloaddition click reaction. The α‐yne‐terminated PMPCS was synthesized by Cu(I)‐catalyzed atom transfer radical polymerization initiated by a yne‐functional initiator. Poly(vinylbenzyl azide) was prepared by polymerizing vinylbenzyl chloride using nitroxide mediated radical polymerization to obtain poly(vinylbenzyl chloride) as the precursor which was then converted to the azide derivative. The chemical structure and architectures of PMPCS comb polymers were confirmed by ¹H NMR, gel permeation chromatography, and multiangle laser light scattering. Both surface morphologies and solution behaviors were investigated. Surface morphologies of PMPCS combs on different surfaces were investigated by scanning probe microscopy. PMPCS combs showed different aggregation morphologies when depositing on silicon wafers with/without chemical modification. The PMPCS comb polymers transferred to polymer‐modified silicon wafers using the Langmuir‐Blodgett technique showed a worm‐like chain conformation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and crosslinking of biphenyl and naphthalene liquid‐crystalline polyethers with pendant full‐saturated and vinyl‐terminated aliphatic chains

Two series of vinyl‐terminated, side‐chain liquid‐crystalline polyethers containing 4,4′‐biphenyl and 2,6‐naphthalene moieties as mesogenic cores with several contents of vinyl crosslinkable groups were synthesized by chemically modifying poly(epichlorohydrin) with mixtures of saturated and vinyl‐terminated mesogenic acids. In most cases the degree of modification was over 90%. The polymers were characterized by chlorine analysis, IR and ¹H and ¹³C NMR spectroscopies, viscometry, size exclusion chromatography/multi‐angle laser light scattering, and thermogravimetric analysis. The liquid‐crystal behavior of all the synthesized polymers was examined by differential scanning calorimetry, polarized optical microscopy (POM), and X‐ray diffraction on mechanically oriented samples. The crosslinking of most polymers was done by peroxide‐type initiators, which generally led to liquid‐crystal elastomers. The mesophase organization was maintained on the crosslinked materials, as confirmed by POM and X‐ray diffraction. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3384–3399, 2003     

Synthesis of novel biodegradable poly(ethylene glycol) analogue:Water-soluble aliphatic polyester with pendant oligo(ethylene glycol) chains

A novel poly(ethylene glycol)(PEG) analogue composed of aliphatic polyester backbone and pendant oligo(ethylene glycol) short chains is reported.The PEG analogue is a copolymer synthesized by ring-opening alternating copolymerization of succinic anhydride with 2-((2-(2-metho xyethoxy)ethoxy)methyl)oxirane.The structure of the copolymer was confirmed by ~1H NMR spectrum.The effects of the monomer feed ratio on the copolymerization were studied and the polymerization mechanism was given.The PEG analogue di...     

Syntheses and structures of three manganese coordination polymers with 1,4- bis (imidazol-1-yl)butane

Three manganese coordination polymers [Mn(bimb)₂(NCS)₂] _n (1), [Mn(bimb)₂(dca)₂] _n (2) and [Mn(bimb)₂(N₃)₂] _n (3) (bimb?=?1,4-bis(imidazol-1-yl)butane, dca?=?dicyanamide) were synthesized and characterized by X-ray crystallography, IR and thermogravimetric analysis. In 1 and 2, each Mn(II) links two Mn(II) atoms by double bimb ligands and extends to form a one-dimensional double chain structure containing the Mn₂(bimb)₂ 22-member metallocycle. 3 constructs a two-dimensional (4,4) network linked by bimb bridges.     

Two-dimensional lanthanide coordination polymers with bis(diphenylphosphino)hexane dioxide. The determination of the polymeric structure from twinned crystals

Lanthanide nitrates and bis(diphenylphosphino)hexane dioxide (dpphO₂) formed under solvothermal conditions a series of coordination polymers [Ln(dpphO₂)₂(NO₃)₂](NO₃) (Ln = Pr (1), Nd (2), Sm (3), Dy (4), Lu (5)), featuring two-dimensional network structure of the (4, 4) topology. The compounds [Ln(dpphO₂)₂Cl₂]Cl (Ln = Pr (6), Nd (7), Gd (8)) were obtained from corresponding chlorides. Coordination polymer 7 formed regular single crystals of the orthorhombic Pna₂₁$\mathit{Pna}{2}_1$ space group. The nitrate complexes crystallized in the orthorhombic Aea2 space group, however, the crystals were pseudo-merohedral twins simulating a tetragonal diffraction pattern. Unlike our previously characterized neutral polymers with bis(diphenylphosphino)ethane dioxide, all present coordination networks are cationic, with anions located between or within the two-dimensional layers.     

The architectures of 1D coordination polymers with the versatile 7-chloroquinoline-4-alanine ligand mediated by anions: Syntheses,structures and luminescent properties

Three new coordination polymers, [Cd(cqaH)(cqa)Cl]_n (1), [Cd(cqaH)(cqa)Br]_n (2) and {[Cd₂(cqa)₄] · 3H₂O}_n (3) (Hcqa = 7-chloroquinolin-4-alanine, cqaH = the Hcqa ligand, where the proton is transferred from the acid group to the imine group) have been prepared under hydrothermal conditions and characterized by X-ray structural analyses. Both complexes 1 and 2 possess 1D ribbon-like chains, and complex 3 features a 1D double-stranded chain. Various coordination fashions and supramolecular networks are observed in complexes 1–3 due to the versatile coordination modes of the ligand and the cooperative effect from anions in the assemblies. In addition, the luminescent properties for all compounds have been investigated in the solid state.     

Synthesis,structures, and fluorescence of two cadmium(II) coordination polymers with a semirigid bis-benzimidazole

Compounds [CdLCl₂] _n (1) and {[Cd(L)₂(ClO₄)]·ClO₄} _n (2), where L?=?1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, have been synthesized by hydrothermal method, and characterized by element analysis, IR spectra, Powder XRD, and X-ray crystallographic diffraction. Cd(II) in 1 and 2 are both trigonal bipyramidal. Different cadmium salts of chloride and perchlorate lead to different configurations of [Cd₂L₂]²⁺, trans-form in 1 but trans and cis-forms in 2. The 1-D beaded chains of 1 are further linked to generate a 3-D supramolecular architecture by strong π–π stacking interactions as well as intermolecular C–H?···?Cl hydrogen bonds. In 2, the 1-D beaded chains are further assembled by intermolecular C–H?···?O hydrogen bonds to form a 2-D layer. Solid-state fluorescent properties of 1 and 2 were investigated at room temperature.