Polymers 2b Research Articles

Selective uptake and removal of aromatic and heterocyclic compounds by para-dicyanobenzene-linked, EFe3(CO)9-incorporated (E = Te, Se), semiconducting Cu chain polymers

The uptake and removal of volatile and toxic organic compounds is an important issue in modern industrial chemistry because these organic pollutants have long-term effects on public health and the global environment. In this work, we successfully synthesized two novel para-dicyanobenzene (p-DCB)-linked, EFe3(CO)9-incorporated (E = Te, Se) 1D polymers [EFe3(CO)9Cu2(p-DCB)1.5]n (E = Te, 1a; Se, 1b) from liquid-assisted grinding (LAG) of the di-Cu compounds [EFe3(CO)9Cu2(MeCN)2] with p-DCB. Polymers 1a and 1b had isomorphous structures with single- and double-p-DCB linkers alternatively connected to Cu atoms of EFe3(CO)9Cu2 (E = Te, Se) cores, in which two p-DCB of the double-p-DCB moiety were parallel-displaced with the π···π interaction on their benzene rings. The selective adsorption of C7−C10-alkyl aromatics, polycyclic aromatics, and heterocyclic compounds by 1a and 1b was accomplished via neat grinding or THF-aided LAG processes. These reactions led to the formation of the guest molecule (G)-intercalated products, i.e., 1a- and 1b-based polymers [EFe3(CO)9Cu2(p-DCB)1.5·(G)m]n [E = Te, 1a·mG; E = Se, 1b·mG; m = 0.5 or 1] and the THF-introduced single-p-DCB-bridged polymer [TeFe3(CO)9Cu2(p-DCB)·(THF)]n (2a·1THF). These adsorption activities of 1a and 1b were thoroughly evaluated by single-crystal and powder X-ray analysis and TGA and DSC measurement, where some C−H···π, π···π, and C−H···E (E = O, S) interactions between guest molecules and the p-DCB linkers were observed to stabilize polymer chains. The desorption of volatile heterocyclic (THF, furan, thiophene) or alkyl aromatic (toluene, m-xylene, mesitylene, durene) guest molecules to give the parent polymers 1a and 1b could be achieved by vacuum and recrystallization or stepwise LAG process in the Te system. Importantly, these EFe3(CO)9Cu2-incorporated (E = Te, Se) polymers 1a and 1b, as well as their host−guest adducts, exhibited semiconducting behaviors possessing tunable energy gaps (1.36−1.51 eV) with moderate electrical conductivities ((1.21−6.55)×10–7 S·cm–1), in which the guest molecules played a crucial role in modulating the electron transport in the solid state.

Bivalent monomer bearing styryl and five‐membered cyclic dithiocarbonate moieties for orthogonal radical and cationic ring‐opening polymerizations

AbstractWe synthesized a novel bivalent monomer 1 bearing 4‐vinylbenzyl group and five‐membered cyclic dithiocarbonate. This monomer 1 was polymerized orthogonally by free radical polymerization to afford polystyrene 1a bearing a five‐membered cyclic dithiocarbonate moiety in the side chain. On the other hand, cationic ring‐opening polymerization of five‐membered cyclic dithiocarbonate in the monomer 1 successfully proceeded, resulting in a narrow molecular weight distribution of polydithiocarbonate 1b bearing a 4‐vinylbenzyl group in the side chain. Furthermore, post‐polymerizations of 1a and 1b maintaining the polymerizable functionality were carried out respectively by suitable polymerization methods. The five‐membered cyclic dithiocarbonate of 1a underwent cationic ring‐opening polymerization with a high molar ratio of methyl trifluoromethanesulfonate at a high temperature compared to the case of monomer 1, whereas radical polymerization of the 4‐vinylbenzyl group of 1b successfully proceeded under the almost same conditions as the case of monomer 1. These post‐polymerizations achieved the synthesis of corresponding networked polymers 2a and 2b.

Conjugated helical polymers: End-group control and coupling reactions

Telechelic helical poly(phenyleneethynylene)s 2 and 3 bearing end iodo and ethynyl groups were synthesized by the Sonogashira–Hagihara coupling reaction of prepolymer 1 with N-α-tert-butoxycarbonyl-3,5-diiodo-4-hydroxy-d-phenylglycine hexylamide (4) and p-diethynylbenzene (5), respectively. Polymer 2 was treated by Sonogashira–Hagihara coupling reaction with 1,6-diethynylpyrene (a) and 4,4-diethynylbiphenyl (b) to obtain the corresponding polymers 2a and 2b. Polymer 2 was also subjected to the Mizoroki–Heck coupling reaction with diphenyl(p-vinylphenyl)phosphine (e) to obtain the corresponding polymer 2e, and the incorporation of the phosphine moieties was confirmed by 31P NMR spectroscopy. In a similar fashion, polymer 3 was polymerized with 1,4-dibromonaphthalene (c) and 9,10-dibromoanthracene (d), but no concrete evidence for the formation of polymers 3c and 3d was observed. Circular dichroism (CD) spectroscopic analysis revealed that all the polymers adopted folded helical conformations with predominantly one-handed screw sense in CHCl3. The polymers exhibited photoluminescence (PL) depending on the incorporated functional groups.

Poly(p-phenylenediethynylene phosphine)s and Related π-Conjugated Phosphine–Diyne Polymers: Synthesis, Characterization and Photophysical Properties

Despite the considerable synthetic challenge, polymers that incorporate phosphorus atoms within or adjacent to a π-conjugated backbone framework are of interest due to the ability to modulate the photophysical properties of the polymer based on the chemical environment at phosphorus. We report the synthesis and characterization of poly(p-phenylenediethlynylene phosphine)s, 1a–1e, a new class of σ–π conjugated polymer. Polymers 1a–1e were prepared by a Ni-catalyzed coupling of dialkynes with phenyldichlorophosphine in the presence of excess triethylamine and have molecular weights (Mw) up to 12,000 g mol–1 (vs. polystyrene). While the polymers 1b–1e are nonfluorescent, blue fluorescence is observed upon oxidation of the phosphorus centers (Φsoln = 0.12–0.28). Polymers 1b·O–1e·O also exhibit yellow/green fluorescence in the solid state (Φsolid = 0.04–0.08). These results introduce a fascinating new class of main group-containing macromolecule and lay the groundwork for their utilization in sensory applicati...

Synthesis and ion responsiveness of optically active polyacetylenes containing salicylidene Schiff-base moieties

Acetylenic monomers containing salicylidene Schiff-base groups (1a and 1b) as well as Schiff-base and hydroxy groups (1c) were synthesized and polymerized with [(nbd)RhCl]2/Et3N catalyst to afford the corresponding polymers 2a–c with high molecular weights (Mn=2.6–7.2×105) in high yields (75–97%). Polarimetric, circular dichroism (CD), and UV–vis spectroscopic analyses indicated that the polymers formed helical structures with a predominantly one-handed screw sense. The addition of metal ions to salicylidene Schiff-base-containing polymers 2a and 2b produced insoluble polymer/metal complexes through ionic cross-linking as a result of salicylaldimine–metal ion complexation. Polymers 2b and 2c underwent a helix–coil transition upon the addition of HSO4−, whereas these polymers did not exhibit responsiveness to other anions, such as F−, Cl−, and Br−.

Uncatalyzed synthesis of polyphenylacetylene cross-linked by viologen groups and their chemical properties

Polyphenylacetylenes cross-linked with viologen groups (polymers 1a and 1b) were obtained from the reaction of 4-ethynylaniline with 1,1′-bis(2,4-dinitrophenyl)-4,4′-bipyridinium dichloride (salt 1) and the reaction of 4-(1-trimethylsilylethynyl)aniline with salt 1, followed by the deprotection of the trimethylsilyl group. Model compound (model 1) was synthesized by the reaction of 4-ethynylaniline with 1-(2,4-dinitrophenyl)-4,4′-bipyridinium chloride (salt 2). Ultraviolet–visible spectra revealed that the polymers 1a and 1b had an expanded π-conjugation system along the polymer chain: the polymer showed an onset position of absorption at a wavelength approximately 100 nm longer than the corresponding wavelengths of the model compound. Polymers 1a and 1b received a two-step electrochemical reduction in the viologen group within the polymer and an electrochemical oxidation of the polymer backbone.

Halido‐Bridged 1D Mixed‐Valence CuI–CuII Coordination Polymers Bearing a Piperidine‐1‐carbodithioato Ligand: Crystal Structure, Magnetic and Conductive Properties, and Application in Dye‐Sensitized Solar Cells

AbstractNew mixed‐valence CuI–CuII 1D coordination polymers of the structure [CuI2CuIIX2(Pip‐dtc)2(CH3CN)2]n [Pip‐dtc = piperidine‐1‐carbodithioate; X = Br (1a), I (1b)] containing a dithiocarbamate derivative have been synthesized and structurally characterized by X‐ray diffraction. The 1D infinite chains were formed from mononuclear copper units [Cu(Pip‐dtc)2] connected by bromido‐ or iodido‐bridged copper dinuclear units that include acetonitrile ligands {i.e., [Cu2X2(CH3CN)2]}. Evaluation of the magnetic properties of 1a and 1b revealed that these complexes displayed relatively strong antiferromagnetic interactions [J = –20.4 cm–1 (1a) and J = –18.8 cm–1 (1b)] between unpaired electrons of the copper(II) ions through the dinuclear halido–copper(I) units. Impedance spectroscopy revealed that complexes 1a and 1b exhibit intriguing semiconducting properties at activation energies of Ea = 0.78 eV (1a) and Ea = 0.62 eV (1b). Coordination polymers 1a and 1b were then adopted as the sensitizing material in dye‐sensitized solar cells (DSSCs).

Synthesis of silyl-disubstituted poly(p-phenylenevinylene) membranes and their gas permeability

p-Bis(bromomethyl)benzene with two silyl groups [SiMe2-n-C8H17, SiMe3 (1a), SiMe2-n-C8H17, SiEt3 (1b), SiMe2-n-C8H17, SiMe2-n-C8H17 (1c), SiMe2-n-C8H17, SiMe2-n-C18H37 (1d), SiMe2-n-C18H37, SiMe2-n-C18H37 (1e)] were polymerized by Gilch method to afford silyl-disubstituted poly(p-phenylenevinylene)s (2a–e). The polymers containing SiMe3 groups (2a) showed poor solubility and dissolved in only CHCl3. On the other hand, the other polymers (2b–e) exhibited good solubility in common organic solvents. According to thermogravimetric analysis (TGA), the silyl-disubstituted poly(p-phenylenevinylene)s showed high thermal stability (thermal decomposition temperature: Td ≥ 310 °C). Polymers 2a–e had relatively high molecular weight over 7.6 × 104, and gave free-standing membranes by solution casting method. Except 2e, the oxygen permeability coefficients (PO2) of membranes of the silyl-disubstituted poly(p-phenylenevinylene)s increased as increasing alkyl length of silyl groups (2a: 5.4, 2b: 6.0, 2c: 15.0, 2d: 20.4 barrers). The membrane of 2e having two dimethyl-n-octadecylsilyl groups in the repeating unit exhibited the lowest gas permeability among the present polymers, and its PO2 was 1.8 barrers. This is because polymers 2a–d were amorphous while 2e was crystalline. The PO2 values for amorphous poly(p-phenylenevinylene)s increase in direct proportion to the number of carbon in the side chains.

Zinc, cobalt and copper coordination polymers with different structural motifs from picolyl-triazole hybrid ligands

A series of one-dimensional coordination polymers, viz. [ZnCl2L1]n (1a: 1a-I and 1a-II), [ZnCl2L2]n (1b), [ZnCl2L3]n (1c), {[Co(L1)2(OH2)2]·(ClO4)2·(H2O)2}n (2a), {[Co(L2)2(OH2)2]·(ClO4)2·(H2O)2}n (2b), {[Cu(L1)2(OH2)2]·(ClO4)2·(H2O)2}n (3a), {[Cu(L2)2(OH2)]·(ClO4)2·(H2O)·(MeOH)}n (3b), and {[Cu(L3)2(OH2)]·(ClO4)2·(H2O)2}n (3c), and a three-dimensional coordination polymer [Cu2I2L3]n (4c) have been synthesized by self-assembly of 4-picolyl substituted 1,2,3-triazoles, viz.1-(4-picolyl)-4-butyl-1H-1,2,3-triazole (L1), 1-(4-picolyl)-4-pentyl-1H-1,2,3-triazole (L2) and 1-(4-picolyl)-4-hexyl-1H-1,2,3-triazole (L3), with appropriate metal salts. These coordination polymers have been characterized by single-crystal and powder X-ray diffraction (XRD) and thermogravimetric analyses (TGA). Complexes 3a–c have been subject to EPR analysis. Complexes 1a–c are 1D coordination polymers formed by singly bridging L1–L3 using their picolyl and 3-positioned nitrogen. Their modes of propagation (zig-zag, helical and wave-like) vary with the length of the alkyl pendant at the 4-position on the triazole moiety. Centro-symmetric polymers 2a and 2b are formed by doubly bridging spacers as 1D chains of 18-membered metallocycles fused at octahedral Co(II) centers with coordinated aqua ligands with extensive water–ClO4− H-bonding. Cu(II) complex 3a (space groupP21/n) is isostructural with 2a, but 3b and 3c crystallize with a chiral space group (P21) with square pyramidal Cu(II) doubly bridged by L2 and L3 to give 1D macrocyclic chiral chains. The spacer in 4c shows uniquely high coordination ability by engaging the donor functions of the nitrogen, not only at the picolyl and 3-position but also at the 2-position of the triazole. The resultant 3D polymer network is neutral and solvate free and has higher symmetry (space groupI41/a) than 4a and 4b. The spontaneous resolution of 3b and 3c is traced to the configurational characteristics of the four ligands and its transfer to the crystal network through space chiral packing. The 1D coordination polymers 1 are thermally most stable, whereas the MeOH-solvated and hydrated perchlorate salt 3b decomposes violently upon heating. Variable temperature photoluminescence (VT-PL) measurements revealed strong low energy (LE) rt emissions for 4a and 4b but not for 4c. The high energy (HE) emissions of 4a–c however increase significantly as temperature decreases. The remarkable variety of structural motifs in these coordination polymers is the result of (a) flexible bonding modes of the picolyl–triazole hybrid ligands, (b) different metal geometry options, (c) halide participation as bridging or capping ligands, (d) possibility of hydrate or solvate coordination and (e) extensive H-bonding involving anionic perchlorate methanol solvate as well as hydrates that are coordinated directly (viz. primary) and indirectly (viz. secondary) to the metal.

Coordination polymers with chelidonate (4-oxo-4 H-pyran-2,6-dicarboxylate) anions and dmso: [Zn(chel)(dmso) 2] and linkage isomers of [Co(chel)(dmso)(OH 2) 3]·H 2O

Recrystallization from dmso of the previously prepared compound [Co(chel)(H 2O) 4] (chel = 4-oxo-4 H-pyran-2,6-dicarboxylate), led to the new one-dimensional coordination polymers 1a and 1b, which are linkage isomers of formula [Co(chel)(dmso)(OH 2) 3]·H 2O. Also the recrystallization from dmso of the previously prepared [Zn(chel)(H 2O) 2] allow the isolation of the one-dimensional coordination polymer [Zn(chel)(dmso) 2] ( 2). [Co(chel)(H 2O) 4] was characterized by elemental analysis, IR and electronic spectroscopy, magnetic measurements at room temperature and thermogravimetric analysis. X-ray single crystal diffraction of 1a, 1b and 2 showed the coordinative behavior of the chelidonate ligand in each compound as well as the different participation of this ligand in the corresponding metallosupramolecular organization.

Synthesis of poly(p-phenyleneethynylene)s bearing oligo-ethylene glycols and their gas permeation properties

1,4-Diiodobenzenes bearing oligo-ethylene glycols [IRC6H2IR, R = OCH2CH2OCH3 (1a), O(CH2CH2O)2CH3 (1b), O(CH2CH2O)3CH3 (1c)] were polymerized with 1,4-diethynylbenzene in the presence of Pd/Cu catalyst to afford poly(p-phenyleneethynylene)s bearing oligo-ethylene glycols (2a–c), respectively. Polymer 2a was insoluble in any solvents, but the other polymers (2b, 2c) were soluble in CHCl3. The weight-average molecular weights of 2b and 2c were 5.4 × 104 and 9.6 × 104, respectively, and they gave free-standing membranes by solution-casting method. The densities of membranes of 2b and 2c were 1.26 and 1.22 g/cm3, respectively, and their carbon dioxide permeability coefficients were 12.9 and 13.5 barrers, respectively. The CO2/N2 separation factor of membrane of 2b was as large as 33.7. Membrane of 3b, which contains triethylene glycols, exhibited higher CO2 permselectivity, and the CO2/N2 separation factor was 50.0.

Synthesis and characterization of benzocyclobuten-4-yl acrylate monomer and its radical polymerization

A benzocyclobuten-4-yl acrylate (1) monomer was prepared by esterification of 4-hydroxybenzocyclobutene with acryloyl chloride. The radical homopolymerization of 1 and copolymerization of 1 with styrene or n-butyl acrylate were carried out to produce linear polymers 2a, 2b and 2c. Heating of these linear polymers under thermal initiation gave corresponding cross-linked polymers 3a, 3b and 3c. The ring-opening reaction in the cross-linking process was confirmed by on-line infrared spectra. Differential scanning calorimetry showed that the glass transition temperatures of linear polymers 2a and 2b were 83.2°C and 68.1°C, respectively. Thermogravimetric analysis of the cross-linked polymers showed that they all exhibited good thermal stability.

Synthesis and gas permeability of poly(p-phenyleneethynylene)s having bulky alkoxy or alkyl groups

Dipropynylbenzene with branched alkoxy and alkyl groups [CH3C≡CRC6H2RC≡CCH3, R = 2-methylpropoxy (1a), 3-methylbutoxy (1b), 4-methylpentoxy (1c), cyclohexylmethoxy (1d), 2-ethylhexoxy (1e), 2-octoxy (1f), 2-ethylhexyl (1g), and 2-octyl (1h)] were polymerized with Mo(CO)6 in the presence of 4-(trifluoromethyl)phenyl to afford poly(2,5-di(alkoxy or alkyl)-p-phenyleneethynylene)s (2a–h). Polymer 2a was insoluble in any solvents, but the other polymers (2b–h) were soluble in common organic solvents. The polymers with relatively long side chains (2e–h) had high molecular weight over 1.6 × 104 and gave free-standing membranes by solution-casting method. The densities of membranes of 2e–h were 0.914–0.998, and their fractional-free volume values were relatively large (0.094–0.158). The oxygen permeability coefficients of membranes of 2e–h were 18.4, 12.7, 4.85, and 19.3 barrers, respectively. It was found that poly(p-phenyleneethynylene) with 2-octyl side groups, which have the branch at the nearest position from main chain, exhibited the highest gas permeability.

The microwave-assisted synthesis and characterization of novel, octakis(2-hydroxyethoxy)resorcinarene bridged polymeric metallophthalocyanines

The new metallophthalocyanine (Zn, Cu, Ni, Co) polymers containing 4,6,10,12,16,18,22,24-octakis(2-hydroxyethoxy)-2,8,14,20-tetramethylresorcinarene are described. Firstly, 4,6,10,12,16,18,22,24-octakis(2-hydroxyethoxy)-2,8,14,20-tetramethylresorcinarene compound ( 1) was synthesized by treating resorcinarene with 2-chloroethanol under microwave irradiation. Then, tetrakis(4,5-bis(2-hydroxyethoxy))phthalonitrile substituted resorcinarene compound ( 2) and octakis(4-(2-hydroxyethoxy))phthalonitrile substituted resorcinarene compound ( 3) were synthesized by treating compound ( 1) with 4,5-dichloro-1,2-dicyanobenzene and 4-nitro-1,2-dicyanobenzene, respectively, under microwave irradiation. The chlorides Cu (II), Ni (II), Co (II), were employed in order to synthesize the corresponding metallophthalocyanine polymers ( 2b– d and 3b– d) and Zn(CH 3COO) 2 was used for the preparation of zinc phthalocyanine polymers ( 2a and 3a). All products were synthesized by microwave-assisted synthesis method. The structures were characterized by elemental analyses, 1H NMR, 13C NMR, UV–Vis and FTIR spectroscopy.

Synthesis of PEG‐functionalized poly(diphenylacetylene)s and their gas permeation properties

AbstractThe polymerizations of 1‐(3‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene (1a) and 1‐(4‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene (1b) were carried out with TaCl5‐n‐Bu4Sn to give relatively high‐molecular‐weight polymers (2a and 2b) (Mn > 5 × 105). The obtained polymers were brominated by using benzoyl peroxide and N‐bromosuccinimide first, followed by substitution reaction of three types of polyethylene glycol. When diethylene glycol was used as a reagent on substitution reaction of meta‐substituted polymer, PEG‐functionalized poly(diphenylacetylene) with the highest content of oxyethylene unit [4a(2)] was obtained, and the degree of substitution was 0.60. The degrees of substitution decreased to 0.15 and 0.08 when the polyethylene glycols with higher molecular weights were used. PEG‐substitution reaction to the para‐substituted polymers was difficult to proceed, and hence the degree of substitution was 0.18 even when diethylene glycol was used. The CO2/N2 separation factor of PEG‐functionalized polymer [4a(2)] was as large as 28.8, although that of 2a was 7.41. The other PEG‐functionalized polymers also exhibited high CO2 permselectivity, and their CO2/N2 separation factors were over 20. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Syntheses, Structures, and Characterizations of Two Pairs of Cd(II)-5-Aminotetrazolate Coordination Polymers

Two pairs of Cd(II)-5-aminotetrazolate coordination complexes, {[Cd(5-HATZ)2(H2O)2(μ2-SO4)]·H2O}n (1a) and [Cd5(5-ATZ)4(μ3-OH)2(μ5-SO4)2]n (1b), [Cd(5-HATZ)2(μ2-Cl)2]n (2a), and [Cd3(5-ATZ)4(MeCN)2(μ2-Cl)2]n (2b), have been synthesized and structurally characterized. At room temperature 1D single-bridged and double-bridged chain-like compounds 1a and 2a were isolated by solution evaporation method. Under hydrothermal synthesis at 180 °C, two three-dimensional coordination polymers 1b and 2b were isolated from compounds 1a and 2a, respectively. 1b is constructed by 3D [Cd5(μ5-SO4)2(μ3-OH)2]n4+ network templated by 5-ATZ anions. 2b exhibits the 3D metal-organic framework with a (8.122)(844.122)(42.124) topology. 5-Aminotetrazolate is a terminal ligand in 1a and 2a, whereas it is three-coordinated and/or four-coordinated in 1b and 2b. Thermal studies show that high-dimensional structures have higher thermal stability than that of 1D structures.

Synthesis and properties of various poly(diarylacetylenes) containing siloxy and hydroxy groups

AbstractDiarylacetylene monomers (1b−f) containing siloxy and either naphthyl, fluorenyl, or biphenyl groups were polymerized with TaCl5–n‐Bu4Sn catalyst, and 1b, 1c, and 1f provided high molecular weight polymers. Free‐standing membranes of polymers 2b, 2c, and 2f were fabricated by casting from toluene solution. Desilylation of these polymer membranes was carried out with trifluoroacetic acid to afford poly (diarylacetylenes) membranes having hydroxy groups (3b and 3c). According to thermogravimetric analysis (TGA), both siloxy‐containing and hydroxy‐containing polymers exhibited high thermal stability, and the onset temperatures of weight loss in air were ∼370 °C and ∼430 °C, respectively. The CO2 permeability coefficients of these membranes were in the range of 65–640 barrers. The points of 3b and 3c in the PCO2 versus PCO2/PCH4 plot were located above Robeson's upper bound. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4487–4495, 2007

Synthesis and degradation of poly(beta-aminoester) with pendant primary amine

Three poly(beta-aminoester)s with pendant primary amines were synthesized by Michael addition of N-Boc-protected diamine to 1,4-butanediol diacrylate, followed by removal of N-Boc-protective group under anhydrous acidic conditions. The degradation rate of poly(beta-aminoester)s with pendant primary amines is dependant on their side-chain structures and pH value of incubation buffer. The degradation in basic environments is much faster than in acidic environments. The degradation of poly(beta-aminoester) with pendant primary amine involves intramolecular/intermolecular amidation and hydrolytic degradation. Under physiological conditions, the intramolecular/intermolecular amidation of poly(beta-aminoester) plays an important role in the polymer degradation. Polymers 1a– 1c show significant buffer capacity at pH 4–10. The cytotoxicity of polymer 1a is much higher than that of polymers 1b and 1c.

Synthesis and characterization of poly(diphenylacetylenes) containing both hydroxy and halogen/alkyl groups as gas separation membranes

Diphenylacetylene containing siloxy and halogen/alkyl groups ( P- t-BuMe 2SiO-C 6H 4C CC 6H 4- p-X, X = Cl, Br, I, Me, Et, 1b– f, respectively) were polymerized with TaCl 5- n-Bu 4Sn catalyst to provide high molecular weight polymers ( 2b– f) in good yields. These polymers afforded tough free-standing membranes by casting from toluene solution. Desilylation of these siloxy-containing polymer membranes was carried out with trifluoroacetic acid to give membranes of poly(diphenylacetylenes) having hydroxy and halogen/alkyl groups ( 3b– f). Polymers 2b– f were soluble in nonpolar solvents such as cyclohexane, toluene, and THF, while polymers 3b– f were insoluble in these solvents. The oxygen permeability coefficients ( P O 2 ) of membranes 2b– f and 3b– f were in the range of 140–280 and 12–190 barrers, respectively. The gas permeabilities of most membranes ( 2b– e and 3b– f) were higher than those of the corresponding polymer membranes without halogen/alkyl substituents ( 2a and 3a), suggesting that introduction of small spherical groups (halogen and methyl) into the polymers 2a and 3a enhances gas permeability. The incorporation of halogen atoms into the present membranes was more effective to improve gas permeability than methyl and ethyl groups. The points of 3b– e in the P C O 2 versus P C O 2 / P N 2 and P C O 2 / P C H 4 plots were located obviously above Robeson's upper bound.

Synthesis of Highly Water-Soluble Fluorescent Conjugated Glycopoly(p-phenylene)s for Lectin and Escherichia coli

Two facile, convenient, and versatile synthetic approaches are used to covalently attach carbohydrate residues to conjugated poly(p-phenylene)s (PPPs) for highly water-soluble PPPs bearing alpha-mannopyranosyl and beta-glucopyranosyl pendants (polymers A and B), which highly fluoresce in phosphate buffer (pH 7.0). The post-polymerization functionalization approach is to treat bromo-bearing PPP (polymer 1) with 1-thiolethyl-alpha-D-mannose tetraacetate or 1-thiol-beta-D-glucose tetraacetate in THF solution in the presence of K(2)CO(3) at room temperature through formation of thioether bridges, affording polymer 2a or 2b. The prepolymerization functionalization approach is to polymerize a well-defined sugar-carrying monomer, affording polymer 2a. Polymers 2a and 2b were deacetylated under Zemplén conditions in methanol and methylene chloride containing sodium methoxide, affording polymers A and B, respectively. The multivalent display of carbohydrates on the fluorescent conjugated glycopolymer overcomes the characteristic low binding affinity of the individual carbohydrates to their receptor proteins. Titration of concanavalin A (Con A) to alpha-mannose-bearing polymer A resulted in significant fluorescent quenching of the polymer with Stern-Volmer quenching constant of 4.5 x 10(7). Incubation of polymer A with Escherichia coli (E. coli) lead to formation of fluorescently stained bacterial clusters. Beta-glucose-bearing polymer B displayed no response to Con A and E. coli.