Dendronized linear polymers via "click chemistry"

Dendronized linear polymers are prepared from dendritic azides and poly(vinylacetylene) using "click chemistry." The Cu(I)-catalyzed Huisgen [2 + 3] cycloaddition is quantitative up to the third generation.     

Click-chemistry as an efficient synthetic tool for the preparation of novel conjugated polymers

The Cu(I)-catalysed 1,3-dipolar "click" cycloaddition is utilised as an efficient reaction for the preparation of novel fluorene-based conjugated polymers.     

Dipyridyl bridged coordination polymers of Cu(II): Synthesis,crystal structure and magnetic study

Two coordination polymers, [Cu(bpp)(H₂O)₂(ClO₄)₂]_n (1) and {[Cu(bpds)₂(ClO₄)₂] · 1.5(H₂O)}_n (2) [bpp, 1,3-bis(4-pyridyl)propane and bpds, 4,4′-bipyridyl disulfide] have been synthesized and characterized by X-ray single crystal diffraction study and magnetic measurement. Both the coordination polymers display 1D chains with perchlorate anions acting as pendant ligands. In 1 undulated polymers are built by Cu(H₂O)₂(ClO₄)₂ units connected by single bpp and in complex 2 Cu(ClO₄)₂ fragments are linked by pairs of bpds ligands to form a double-stranded chain. The crystal packing evidences polymers of 1 involved in weak H-bonding interactions leading to a 3D supramolecular network. Magnetic study reveals weak antiferromagnetic interactions in both complexes.     

Influence of anions on the dimensionality of extended networks based on Cu I cations and 1,4,5,8,9,12-hexaazatriphenylene (HAT) ligands

Reactions of Cu I salts with 1,4,5,8,9,12-hexaazatriphenylene (HAT) afford three types of cationic coordination polymers depending on the anion present in the reaction solution. In the crystal structure of {[Cu(HAT)][BF4]x1/3(C6H6)}infinity, (1), Cu ions and HAT molecules form extended layers that are best described as strongly distorted honeycomb nets. The space between the layers is occupied by [BF4]- anions and solvent molecules. {[Cu(HAT)][PF6]}infinity, (2), crystallizes as a chiral (10,3)-a net with [PF6]- anions residing in the cavities of the three-dimensional metal-organic framework. The crystal structure of {[Cu4(HAT)3][SbF6]4x3C6H6}infinity, (3), is based on unique extended [Cu4(HAT)3]infinity "nanotubules" filled with solvent molecules and [SbF6]- anions.     

Polytypism, homochirality, interpenetration, and hydrogen-bonding in transition metal (Mn(II), Ni(II), Cu(II), Zn(II)) 5-hydroxyisophthalate coordination polymers containing 4,4'-bipyridyl

We report the synthesis of five coordination polymers of divalent transition metals combined with 5-hydroxyisophthalic acid (HIP) and 4,4'-bipyridyl (bipy). Mn forms two polytypic two-dimensional coordination polymers, Mn(HIP)(bipy).3H(2)O and Mn(HIP)(bipy).(1/4)bipy.2H(2)O (I and II, with ABAB and ABC stacking sequences, respectively); Ni forms a chiral hexagonal three-dimensional coordination polymer with two interpenetrating trigonal sublattices exhibiting the "dual quartz" topology, Ni(HIP)(bipy)(H(2)O) (III); Cu forms a one-dimensional coordination polymer containing arrays of infinite hydrogen-bonded molecular ribbons, Cu(HIP)(2)(bipy) (IV); and Zn forms a two-dimensional coordination polymer with a stair-stepped layered structure, Zn(2)(HIP)(2)(bipy)(H(2)O)(2).H(2)O (V). The M-HIP-M connections are perpendicular to the M-bipy-M connections in all structures where they are present.     

Helical and network coordination polymers based on a novel C2-symmetric ligand : SHG enhancement through specific metal coordination

Cu(I) and Ag(I) coordination polymers of an axially chiral "push-pull" ligand possess respectively 2-D network and helical structures and the coordination mode strongly influences the solid state SHG reduction/enhancement with respect to the free ligand.     

Solid-state aggregation of metallacyclophane-based Mn(II)Cu(II) one-dimensional ladders

Two distinct one-dimensional (1) and two-dimensional (2) mixed-metal-organic polymers have been synthesized by using the "complex-as-ligand" strategy. The structure of 1 consists of isolated ladderlike Mn(II)(2)Cu(II)(2) chains separated from each other by neutral Mn(II)(2) dimers, whereas 2 possesses an overall corrugated layer structure built from additional coordinative interactions between adjacent Mn(II)(2)Cu(II)(2) ladders. Interestingly, 1 and 2 show overall ferri- and antiferromagnetic behavior, respectively, as a result of their distinct crystalline aggregation in the solid state.     

Mixed-valence copper coordination polymers based on CuSCN or CuN<Subscript>3</Subscript> as bridging motifs

Two novel mixed valence copper coordination polymers, [Cu(2-pac)₂(CuN₃)(H₂O)] _n (1) and [Cu(2-pac)₂(CuSCN)₂] _n (2), have been prepared through hydrothermal synthesis and analyzed for structure determination, which exhibit two- and three-dimensional structures respectively. In complex (1), zigzag chains of [CuN₃] _n running parallel to thec direction are interconnected by Cu(2pac)₂ to form a two-dimensional layer structure. In complex (2), the arrangement of μ-1,1,3 bridging thiocyanate ligand leads to the formation of ten-membered Cu—SCN— Cu—S—Cu—NCS rings, and each Cu atom is further linked by Cu(2-pac)₂ to afford a three-dimensional configuration.     

Synthesis,characterization and X-ray crystal structures of two non-molecular coordination polymers of manganese(II) and copper(II) with <Emphasis Type="Italic">N</Emphasis>-(2-pyridylmethyl)-<Emphasis Type="SmallCaps">l</Emphasis>-alanine and isothiocyanato ligands

The reduced Schiff base, N-(2-pyridylmethyl)-l-alanine (Pyala), has been prepared and used as a ligand for the synthesis of two new non-centrosymmetrical isothiocyanate mixed-ligand coordination polymers, [MnPyalaSCN] _n and [CuPyalaSCN] _n . Pyala and the metal complexes were characterized by physico-chemical and spectroscopic methods. The single-crystal X-ray structures of the complexes reveal both compounds to be non-molecular coordination polymers which crystallize in the orthorhombic system. The ligand acts as a bridge between two metal centres in both compounds, forming two six-membered rings around each Mn atom and two five-membered rings around each Cu centre. The 1D chains are assembled via N–H?O, N–H?S hydrogen bonds and S–S interactions building 3D helical supramolecular networks in both compounds. Packing of the polymers of both compounds along the b-axis gives chiral channels.     

4,4'-Bipyridazine: a new twist for the synthesis of coordination polymers

A new polydentate ligand 4,4'-bipyridazine (4,4'-bpdz) was prepared by employing inverse electron demand cycloaddition of 1,2,4,5-tetrazine. A unique combination of structural simplicity, ampolydentate character and efficient donor properties towards Cu(I), Cu(II) and Zn(II) provide wide new possibilities for the synthesis of coordination polymers incorporating the 4,4'-bpdz module either as a bi-, tri- or tetradentate connector between the metal ions. 1D coordination polymers Cu(2)(4,4'-bpdz)(CH(3)CO(2))(4) x 4H(2)O and Zn(4,4'-bpdz)(NO(3))(2), and interpenetrated (4,4)-nets in [Cu(4,4'-bpdz)(2)(H(2)O)(2)]S(2)O(6) were closely related to 4,4'-bipyridine compounds. 1D "ladder-like" polymer Cu(2)(4,4'-bpdz)(3)(CF(3)CO(2))(4) and the unprecedented 3D binodal net ({8(6)}{6(3);8(3)}) in [Cu(3)(4,4'-bpdz)(6)(H(2)O)(4)](BF(4))(6) x 6H(2)O were based upon a combination of linear and angular organic bridges. Complex [Cu(3)(OH)(2)(4,4'-bpdz)(3)(H(2)O)(2){CF(3)CO(2)}(2)](CF(3)CO(2))(2) x 2H(2)O has a "NbO-like" 3D topology incorporating discrete dihydroxotricopper(II) clusters linked by tri- and tetradentate ligands. The tetradentate function of the 4,4'-bpdz ligand was especially relevant for copper(I) complexes, which adopt layered Cu(2)X(2)(4,4'-bpdz) (X = Cl, Br) or 3D chiral framework (X = I) structures based upon infinite (CuX)(n) chains. The electron deficient character of the ligand was manifested by short anion-pi interactions (O-pi 3.02-3.20; Cl-pi 3.35 A), which may be involved as a factor for controlling the supramolecular structure.     

Semiconducting tellurium-iron-copper carbonyl polymers

The unprecedented ternary Te-Fe-Cu chain polymers [{Et4N}{TeFe3(CO)9Cu}]infinity and [{TeFe3(CO)9Cu2}(mu-4,4'-dipyridyl)1.5]infinity were prepared from the self-assembly of [Et4N]2[TeFe3(CO)9] with [Cu(MeCN)4][BF4] in THF or in the presence of 4,4'-dipyridyl in THF. These two chain polymers, which can also be constructed from the precursor complex TeFe3(CO)9Cu2(MeCN)2, show semiconducting behaviors with low band gaps of 0.59 and 0.41 eV, respectively. In addition, their conductivity and the effect of the bridging ligand are further elucidated by theoretical calculations.     

Synthesis,curing and properties of poly(phthalazione ether sulfone ketone) copolymers crosslinked by click chemistry

Functionalized poly(phthalazinone ether sulfone ketone) was synthesized by successive chloromethylation and azidation, followed by curing reaction with the propargyl end-groups of various molecular weight crosslinking agents in the presence of Cu(Ⅰ) catalyst via the azide-alkyne click reaction. The influences of the chain length of crosslinking agents on the poly(phthalazinone ether sulfone ketone) system were studied. FTIR and DSC tests demonstrated certain crosslinking by azide-alkyne reaction with the formation of triazole ring. DSC results showed that curing temperature shifted to lower temperatures considerably in the presence of Cu(Ⅰ) catalyst. TGA showed cured polymers were of much higher thermal stability, including higher thermal decomposition temperatures and higher char-yielding properties. After being cured, the polymers became insoluble in organic solvents and the gel fraction of the cured polymers exceeded 71%. Wide-angle X-ray diffraction results indicated there was a short distance order in the poly(ether sulfone)(PES) main chain except for the azido methyl poly(phthalazinone ether sulfone ketone) and 4,4'-bis(2-propynyloxy) biphenyl( AMPPESK-BP) system.     

Synthesis of neoglycopolymers by a combination of "click chemistry" and living radical polymerization

The synthesis of novel well-defined alkyne side chain functional polymers featuring narrow molecular weight distributions (PDI = 1.09-1.17) by living radical polymerization is described. Grafting of protected and unprotected carbohydrates is achieved via either a C-6 or an anomeric azide (alpha or beta) onto these polymers by Cu(I)-catalyzed "click chemistry", providing a simple and efficient route to synthetic glycopolymers. The strategy provides an extremely powerful tool for the synthesis of libraries of materials that differ only in the nature of the sugar moiety presented on a well-defined polymer scaffold. A library of multivalent ligands were then prepared following a "coclicking" synthetic protocol, and the reactivity of these glycopolymers in the presence of concanavalin A and Ricinus communis agglutinin, model lectins able to selectively bind appropriate mannose and galactose derivatives, respectively, was assessed.     

Comb Poly(Oligo(2‐Ethyl‐2‐Oxazoline)Methacrylate)‐Peptide Conjugates Prepared by Aqueous Cu(0)‐Mediated Polymerization and Reductive Amination

The controlled synthesis of poly(oligo(2‐ethyl‐2‐oxazoline)methacrylate) (P(OEtOxMA)) polymers by Cu(0)‐mediated polymerization in water/methanol mixtures is reported. Utilizing an acetal protected aldehyde initiator for the polymerization, well‐defined polymers are synthesized (>99% conversion, Ð < 1.25) with subsequent postpolymerization deprotection resulting in α‐aldehyde end group containing comb polymers. These P(OEtOxMA) are subsequently site‐specifically conjugated, via reductive amination, to a dipeptide (NH₂‐Gly‐Tyr‐COOH) as a model peptide, prior to conjugation to the functional peptide oxytocin. The resulting oxytocin conjugates are evaluated in comparison to poly(oligo(ethylene glycol) methyl ether methacrylate) combs synthesized in the same manner for potential effects on thermal stability in comparison to the native peptide.

     

Syntheses and crystal structures of straight or zigzag one-dimensional coordination polymers based on Cu(II) square pyramidal or Cu(I) tetrahedral coordination environments

Two coordination polymers containing copper ions, [Cu(SO₄)(pyz)(H₂O)]_n (1) and [Cu₂(SO₄)(pyz)₂(H₂O)₂]_n (2) (pyz = pyrazine), have been synthesized and characterized by single-crystal X-ray analyses. Compound 1 was synthesized by the reaction of Cu(SO₄) · 5H₂O with pyz (ratio = 1:2) in H₂O at room temperature. The structure of 1 consists of linear chains of [Cu(pyz)(H₂O)]²⁺, with coordinated sulfate ions bridging the chains. Compound 2 was obtained as dark red blocks from the reaction of Cu(SO₄) · 5H₂O and pyz (ratio = 1:2) in H₂O, after heating to 180 °C in a Teflon autoclave for 48 h. The structure of 2 consists of zigzag chains of [Cu(pyz)(H₂O)]⁺ with sulfate ions. Only the difference in the synthesis temperature, room temperature or 180 °C, determines whether Cu(II) or Cu(I) coordination polymers are formed, with the reduction of Cu(II) to Cu(I) being explained by the Gillard mechanism.     

Anion Directed Assembly of Cu(Ⅱ) Complexes Formed by a Flexible Ligand

Coordination polymers,consisting of metal,anion and organic ligands,have attracted much attention.The structure of coordination polymers is affected by various factors.To investigate the effects of anion,syntheses and structures of four Cu(II)complexes,namely[(Cu LCl_2)(PF_6)]_n(1),[(Cu LCl_2)(ClO_4)]_n(2),[(Cu LCl_3)?CH_3OH]_n(3)and Cu LCl_3(4),are reported based on a flexible ligand,1,3-bis(2-pyridylmethyl)imidazolium(L).The ligand is accommodative to kinds of anions,and forms 1-D chains generally upon reaction with Cu(II)salts.The effect is measured by the conformational variation through the dihedral angles between different aromatic rings of the ligand.In order to further investigate the effect of anion,a protonated sample of L,namely,LH(ClO_4)_2?H_2O(5)is also synthesized and structurally characterized,showing an intriguing hydrogen bonded helix.     

Heteroleptic copper dipyrromethene complexes: synthesis, structure, and coordination polymers

The synthesis of neutral [Cu(dpm)2] and [Cu(dpm)(acac)] (dpm = dipyrromethene, acac = acetylacetonato) complexes is presented. The formation of the asymmetric metal complexes was monitored by electronic absorption and infrared spectroscopy. Two of the complexes investigated, containing pyrdpm ligands (pyrdpm = pyridyldipyrromethene), form 1-dimensional coordination polymers. The coordination polymers formed by these complexes have been characterized by single-crystal X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The complexes possess square pyramidal coordination geometries with the apical position occupied by the meso-pyridyl donor of a neighboring complex in the crystal lattice. The features of these coordination complexes that facilitate formation of extended solids have been probed. Symmetric [Cu(pyrdpm)2] complexes are unable to form coordination solids due to steric hindrance at the metal center. Use of cyano donors in complexes such as [Cu(cydpm)(acac)] (cydpm = cyanodipyrromethene) in lieu of pyridyl donors also fail to form network solids. Through these systematic studies, both the basic coordination chemistry of these complexes and the fundamental design requirements for synthesizing this novel class of coordination polymers have been defined.     

Two-dimensional polymer formation on surfaces: insight into the roles of precursor mobility and reactivity

We report on a combined scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) study on the surface-assisted assembly of the hexaiodo-substituted macrocycle cyclohexa-m-phenylene (CHP) toward covalently bonded polyphenylene networks on Cu(111), Au(111), and Ag(111) surfaces. STM and XPS indicate room temperature dehalogenation of CHP on either surface, leading to surface-stabilized CHP radicals (CHPRs) and coadsorbed iodine. Subsequent covalent intermolecular bond formation between CHPRs is thermally activated and is found to proceed at different temperatures on the three coinage metals. The resulting polyphenylene networks differ significantly in morphology on the three substrates: On Cu, the networks are dominated by "open" branched structures, on the Au surface a mixture of branched and small domains of compact network clusters are observed, and highly ordered and dense polyphenylene networks form on the Ag surface. Ab initio DFT calculations allow one to elucidate the diffusion and coupling mechanisms of CHPRs on the Cu(111) and Ag(111) surfaces. On Cu, the energy barrier for diffusion is significantly higher than the one for covalent intermolecular bond formation, whereas on Ag the reverse relation holds. By using a Monte Carlo simulation, we show that different balances between diffusion and intermolecular coupling determine the observed branched and compact polyphenylene networks on the Cu and Ag surface, respectively, demonstrating that the choice of the substrate plays a crucial role in the formation of two-dimensional polymers.     

Copper(I) coordination polymers [{Cu(mu-X)}2{RP(mu-NtBu)}2]n (R = OC6H4OMe-o; X = Cl, Br, and I) and their reversible conversion into mononuclear complexes [CuX{(RP(mu-NtBu)2}2]: synthesis and structural characterization

The reactions of cyclodiphosphazane cis-[tBuNP(OC6H4OMe-o)]2 (1) with 2 equiv of CuX in acetonitrile afforded one-dimensional Cu(I) coordination polymers [Cu2X2{tBuNP(OC6H4OMe-o)}2]n (2, X = Cl; 3, X = Br; 4, X = I). The crystal structures of 2 and 4 reveal a zigzag arrangement of [P(mu-N)(2)P] and [Cu(mu-X)(2)Cu] units in an alternating manner to form one-dimensional Cu(I) coordination polymers. The reaction between 1 and CuX in a 2:1 ratio afforded mononuclear tricoordinated copper(I) complexes of the type [CuX{(tBuNP(OC6H4OMe-o))2}2] (5, X = Cl; 6, X = Br; 7, X = I). The single-crystal structures were established for the mononuclear copper(I) complexes 5 and 6. When the reactant ratios are 1:1, the formation of a mixture of polymeric and mononuclear products was observed. The Cu(I) polymers (2-4) were converted into the mononuclear complexes (5-7) by reacting with 3 equiv of 1 in dimethyl sulfoxide. Similarly, the mononuclear complexes (5-7) were converted into the corresponding polymeric complexes (2-4) by reacting with 3 equiv of copper(I) halide under mild reaction conditions.     

Copper(II)-mediated chiral helicity amplification and inversion of meta-ethynylpyridine polymers with metal coordination sites

meta-Ethynylpyridine polymers bearing metal coordination sites associate with alkyl glycoside guests to show induced circular dichroism (ICD) bands. The addition of a Cu(II) ion changed the intensity or the sign of these ICD bands. The changes suggested chiral helicity amplification or inversion of the polymers by Cu(II)-mediated cross-linking at the coordinating side chains.