Diethyl Dipropargylmalonate Research Articles

Electro-optical and electrochemical properties of poly(1,6-heptadiyne) derivative with a bulky (t-butyldiphenylsiloxy)methyl substituents

ABSTRACTA conjugated cyclocopolymer with a bulky substituents was synthesized via the MoCl5-catalyzed cyclopolymerization of diethyl dipropargylmalonate and 4,4′-bis[(tert-butyldiphenylsiloxy)methyl]-1,6-heptadiyne. The chemical structure of polymer was characterized by NMR (1H-, 13C-), IR, and UV-visible spectroscopies to have a conjugated backbone system with the designed substituents. The polymer showed characteristic UV-visible absorption band and absorption maximum value of 507 nm. Photoluminescence spectrum exhibited maximum peak at 594 nm, which corresponds to the photon energy of 2.09 eV. Band gap of cyclic copolymer was 2.01 eV.

Synthesis and Optical Spectroscopy of Oligo(1,6-heptadiynes) with a Single Basic Structure Prepared through Adamantylimido-Based Molybdenum Wittig and Metathesis Chemistry

Linear oligoenes of 1,6-heptadiynes (derived from dialkyl dipropargylmalonates) with a single basic structure and up to 23 conjugated double bonds were synthesized through Wittig-like reactions between bimetallic Mo-alkylidene compounds and aldehyde-capped oligoenes. The relatively rigid and isomerically pure oligoenes have structures with alternating cis,trans conjugated double bonds in which the cis double bond is part of a cyclopentene ring. Molecular weights have been confirmed through MALDI-MS measurements of samples purified by HPLC. Optical spectra of the purified samples show significant vibronic resolution, even in room temperature samples, and are remarkably similar to those of simple polyenes and carotenoids. Therefore, a systematic investigation of the dependence of the allowed electronic transition energies (electronic origins) on conjugation lengths has become possible. Studies of seven allowed transitions for molecules with 5-23 double bonds (= N) indicate asymptotic convergence (with approximately a 1/N dependence) to a common long polyene limit at approximately 16,000 cm(-1). The convergence of these electronic transitions agrees with theoretical treatments of polyene excited-state energies and is consistent with the absorption spectra of analogous diethyl dipropargylmalonate polymers (1/N approximately 0).

Programmable Digital Memory Characteristics of Nanoscale Thin Films of a Fully Conjugated Polymer

This paper reports for the first time the programmable digital memory characteristics of the nanoscale thin films of a fully π-conjugated polymer, poly(diethyl dipropargylmalonate) (pDEDPM) in the ...

Electro-Optical and Electrochemical Properties of a Conjugated Polymer Prepared by the Cyclopolymerization of Diethyl Dipropargylmalonate

The electro-optical and electrochemical properties of poly(diethyl dipropargylmalonate) were measured and discussed. Poly(diethyl dipropargylmalonate) prepared by (NBD)PdCl2catalyst was used for study. The chemical structure of poly(diethyl dipropargylmalonate) was characterized by such instrumental methods as NMR (1H-,13C-), IR, and UV-visible spectroscopies to have the conjugated cyclopolymer backbone system. The microstructure analysis of polymer revealed that this polymer have the six-membered ring moieties majorly. The photoluminescence peak of polymer was observed at 543 nm, which is corresponded to the photon energy of 2.51 eV. The cyclovoltamograms of the polymer exhibited the irreversible electrochemical behaviors between the doping and undoping peaks. It was found that the kinetics of the redox process of this conjugated cyclopolymer might be controlled by the diffusion-control process from the experiment of the oxidation current density of polymer versus the scan rate.

Binuclear Schrock-Type Alkylidene-Triggered ROMP and Cyclopolymerization of 1,6-Heptadiynes: Access to Homopolymers and ABA-Type Block Copolymers

The molybdenum-based binuclear Schrock-type initiator 1,4-{Mo(N-2,6-(2-Pr)2C6H3)[OCMe(CF3)2]2CH}2C6H4 (1) was used for the ring-opening metathesis polymerization (ROMP) of norborn-2-ene (NBE) and for the cyclopolymerization of a series of 1,6-heptadiynes, i.e., dimethyl dipropargylmalonate (M1), diethyl dipropargylmalonate (M2), di-tert-butyl dipropargylmalonate (M3), 4-(ethoxycarbonyl)-1,6-heptadiyne (M4), 4,4-bis(hydroxymethyl)-1,6-heptadiyne (M5), and 4-(hydroxymethyl)-1,6-heptadiyne (M6) to form the corresponding Mn−X−Mn block copolymers. The polymerization systems M1-1 (monomer M1 polymerized by the action of initiator 1) and M2-1 fulfilled the criteria of a class IV and class V living system, respectively. Poly-M1, poly-M2, poly-M3, and poly-M4 consisted of 40%, 50%, 58%, and 32% 1,2-(cyclopent-1-ene)vinylenes and 60%, 50%, 42%, and 68% 1,3-(cyclohex-1-ene)methylidenes, respectively. Finally, the block copolymers M225-b-M125-CH-1,4-C6H4-CH-M125-b-M225, M135-b-M235-CH-1,4-C6H4-CH-M235-b-M135, M125-b-...

Monolithic Disk‐Supported Metathesis Catalysts for Use in Combinatorial Chemistry

AbstractTwo metathesis catalysts, RuCl2(PCy3)(NHC)(CHPh) (1) [NHC=1‐(2,4,5‐trimethylphenyl)‐3‐(6‐hydroxyhexyl)‐imidazol‐2‐ylidene] and Mo(N‐2,6‐i‐Pr2‐C6H3)(CHCMe2Ph)(BIPHEN) (2) [BIPHEN=(R)‐3,3′‐di‐t‐butyl‐5,5′,6,6′‐tetramethyl‐2,2′‐biphenolate) have been immobilized on polymeric, monolithic discs using a “grafting from” protocol. Monolithic discs were prepared via ring‐opening metathesis polymerization (ROMP) from norborn‐2‐ene (NBE), tris(norborn‐5‐ene‐2‐ylmethyleneoxy)methylsilane [(NBE‐CH2O)3‐SiCH3], 2‐propanol, toluene and RuCl2(PCy3)2(CHPh). Catalyst loadings of 0.55 and 0.7 wt %, respectively, were obtained. Monolithic disc‐immobilized 1 was used in various metathesis‐based reactions including ring‐closing metathesis (RCM), ring‐opening cross metathesis and enyne metathesis. Using 0.23–0.59 mol % of supported 1, turnover numbers (TONs) up to 330 were achieved. Monolithic disc‐immobilized 2 was used in various enantioselective RCM and desymmetrization reactions. Using 9–13 mol % of supported catalyst, excellent yields up to 100% and high enantiomeric excess (ee≤88%) were observed. In both cases, metal leaching was low (≤3 and ≤2%, respectively). In addition, 1 catalyzed the cyclopolymerization of diethyl dipropargylmalonate (DEDPM) to yield poly(ene)s consisting of 5‐membered rings, i.e., cyclopent‐1‐ene‐1‐vinylene units. The polymerization proceeded via non‐stoichiometric initiation yielding polymers with unimodal molecular weight distribution. Using a catalyst to monomer ratio of 1 : 170, molecular weights of Mw=16,400 and Mn=11,700 g/mol, PDI=1.40 were obtained.

Novel metathesis catalysts based on ruthenium 1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidenes: synthesis, structure, immobilization, and catalytic activity.

The synthesis of novel ruthenium-based metathesis catalysts containing the saturated 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene ligand, that is, [RuCl2(NHC)[=CH-2-(2-PrO)-5-NO(2)-C6H3]] (1) and [Ru(CF3COO)2(NHC)[=CH-2-(2-PrO)-5-NO2-C6H3]] (2) (NHC=1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) is described. Both catalysts are highly active in ring-closing metathesis (RCM) and ring-opening cross-metathesis (ROCM). Compound 1 shows moderate activity in enyne metathesis. Compound 2 is not applicable to enyne metathesis since it shows high activity in the cyclopolymerization of diethyl dipropargylmalonate (DEDPM). Poly(DEDPM) prepared by the action of 2 consists of 95% five-membered rings, that is, poly(cyclopent-1-enevinylene)s, and 5 % of six-membered rings, that is, poly(cyclohex-1-ene-3-methylidene)s. The polymerization proceeds in a nonliving manner and results in polyenes with broad polydispersities (1.9< or =PDI< or =2.3). Supported analogues of 2 were prepared by immobilization on hydroxymethyl-Merrifield resin and a monolithic support derived from ring-opening-metathesis polymerization (ROMP). Catalyst loadings of 1 and 2.5%, respectively, were obtained. Both supported versions of 2 showed excellent reactivity. With 0.24-2% of the supported catalysts, yields in RCM and ROCM were in the range of 76-100%. Leaching of ruthenium was low and resulted in Ru contaminations of the products of less than 0.000014% (0.14 ppm).

Design and Application of Amphiphilic Polymeric Supports for Micellar Catalysis

AbstractIn this contribution, the synthesis and application of amphiphilic poly(2‐oxazoline)s with covalently bound transition metal catalysts for reactions in aqueous media is described. In the first example, bipyridine moieties were introduced via living ring‐opening polymerization of functionalized oxazoline monomers and the resulting block copolymers were used as macroligands for ATRP (atom transfer radical polymerization) using Cu(I)Br as active metal species. Furthermore, the fixation of a chiral biphosphane and its use for enantioselective hydrogenation of enamides is presented as well as the fixation of a ruthenium catalyst. The latter one is used for polymerization of diethyl dipropargylmalonate (DEDPM), and represents the first example of an alkyne polymerization using a ruthenium catalyst. In the case of the polymers stable latex particles were obtained

Stereoselective Cyclopolymerization of Diynes: Smart Materials for Electronics and Sensors

AbstractA series of heptadiynes was cyclopolymerized by Schrock initiators to produce poly(ene)s exclusively based on one single repetitive unit, i.e. 1,2‐cyclopent‐2‐enylenvinylenes. Polymers containing virtually solely 1,2‐cyclopent‐2‐enylenvinylene units were obtained by various routes, e.g. by low‐temperature‐initiated cyclopolymerization of diethyldipropargyl malonate (DEDPM). A chiral poly(ene) was prepared from 4‐(ethoxycarbonyl)‐4‐(1S, 2R, 5S)‐(+)‐menthoxycarbonyl‐1,6‐heptadiyne (ECMHD) to determine the configuration of the double bonds and the tacticity of the poly(ene) backbone. Poly(ECMHD) consisted of &gt;96% 5‐membered rings and possessed a tactic, alternating cis‐trans structure. Alternatively, poly(DEDPM) exclusively based on 1,2‐(cyclopent‐1‐enylene)vinylene units was prepared using MoCl5‐n‐Bu4Sn‐EtOH‐quinuclidine (1:1:5:1) and MoOCl4‐n‐Bu4Sn‐EtOH‐quinuclidine (1:1:2:1). The initiator efficiency of MoOCl4‐n‐Bu4Sn‐EtOH‐quinuclidine (1:1:2:1) was as high as 91%, the highest value ever reported for such systems. Multistage polymerizations of DEDPM indicated for both initiator systems that the catalytic species were active for at least 6 hours in the presence of monomer yet did not fulfill the criteria of a truly living polymerization. Finally, a new modification of the Grubbs‐Hoveyda catalyst, Ru(CF3COO)2(CH‐2‐(2,4,5‐(MeO)3‐C6H3)(SIMes) (SIMes=1,3‐dimesityl‐4,5‐dihydroimidazol‐2‐ylidene) allowed the first ruthenium alkylidene‐catalyzed living cyclopolymerization of DEDPM. The different initiators, their properties, the resulting polymerization systems as well as the physical properties of the resulting poly(ene)s are summarized.

Factors relevant for the ruthenium-benzylidene-catalyzed cyclopolymerization of 1,6-heptadyines.

Fourteen metathesis initiators that had been designed for use in the living polymerization of diethyl dipropargylmalonate (DEDPM), including the Hoveyda catalyst [RuCl(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 a), as well as [Ru(CF(3)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 b), [Ru(CF(3)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 c), [Ru(CF(3)CF(2)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 d), [RuCl(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 a), [Ru(CF(3)COO)(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 b), [Ru(CF(3)CF(2)COO)(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 c), [Ru(CF(3)CF(2)CF(2)COO)(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 d), [RuCl(2)(IMes)([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (3 a), [Ru(CF(3)COO)(2)(IMes)([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (3 b), [RuCl(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 a), [Ru(CF(3)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 b), [Ru(CF(3)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 c), and [Ru(CF(3)CF(2)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 d) (IMes=1,3-dimesitylimidazol-2-ylidene; IMesH(2)=1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) were prepared. Living polymerization systems could be generated with DEDPM by careful tuning of the electronic nature and steric placement of the ligands. Although 1 a, 2 a, 3 a, 3 b, and 4 a were inactive in the cyclopolymerization of DEDPM, and initiators 1 b-d did not allow any control over molecular weight, initiators 2 b-d and 4 b-d offered access to class VI living polymerization systems. In particular, compounds 2 b and 4 d were superior. The livingness of the systems was demonstrated by linear plots of M(n) versus the number of equivalents of monomer added (N). For initiators 2 b-d and 4 b-d, values for k(p)/k(i) were in the range of 3-7, while 1 b, 1 c, and 1 d showed a k(p)/k(i) ratio of >1000, 80, and 40, respectively. The use of non-degassed solvents did not affect these measurements and underlined the high stability of these initiators. The effective conjugation length (N(eff)) was calculated from the UV/Vis absorption maximum (lambda(max)). The final ruthenium content in the polymers was determined to be 3 ppm.

Regio- and stereospecific cyclopolymerization of 1,6-heptadiynes

The synthesis of poly(ene)s exclusively based on one single repetitive unit, i.e. 1,2-cyclopent-2-enylenvinylenes is described. Polymers containing >96% 1,2-cyclopent-2-enylenvinylene units were obtained by low-temperature-initiated cyclopolymerization of diethyl dipropargylmalonate (DEDPM) by Mo(N-2,6-i-Pr2-C6H3)(CHCMe2Ph)(OCH(CH3)2)2. In the presence of quinuclidine, 100% five-membered ring structures were realized at room temperature, e.g. using Mo(N-2,6-Me2-C6H3)(CHCMe2Ph)(OC(CH3)3)2. 4-(Ethoxycarbonyl)-4-(1S,2R,5S)-(+)-menthyl-1,6-heptadiyne was cyclopolymerized to determine the configuration of the double bond (i.e. the cis/trans ratio) and the tacticity of the poly(ene) backbone. Poly(4-(ethoxycarbonyl)-4-(1S,2R,5S)-(+)-menthyl-1,6-heptadiyne) again consisted of >96% five-membered rings and possessed an all-trans tactic, presumably isotactic structure. A linear plot of number of monomers added (N) versus molecular weights suggested that the cyclopolymerization of DEDPM proceeded in a living manner. At least a class V living system was confirmed by the stepwise synthesis of poly(DEDPM). Molecular weight distributions (PDIs) of 1.16–1.37 result from ratios of the rate constants for polymerization (kp) to initiation (ki), kp/ki>1. Influences of temperature, the base and steric and electronic effects of the arylimido and alkoxy ligand are presented. Complementary to the use of well-defined Schrock initiators, poly(DEDPM) containing exclusively five-membered rings was accessible by the use of the quaternary systems MoCl5–n-Bu4Sn–EtOH–quinuclidine and MoOCl4–n-Bu4Sn–EtOH–quinuclidine. Though virtually identical polymers were obtained, the polymerization systems themselves were controlled, yet not living as is the case with Schrock initiators. Selected polymer properties such as stability, degradation behavior, conductivity, and thermoresponsive behavior will be discussed.

Regio- and stereospecific cyclopolymerization of 1,6-heptadiynes and 1,5-hexadiynes

The synthesis of poly(ene)s exclusively based on one single repetitive unit, i.e., 1,2- cyclopent-2-enylenvinylenes, is described. Polymers containing >96% 1,2-cyclopent-2-enylenvinylene units were obtained by low-temperature-initiated cyclopolymerization of diethyl dipropargylmalonate (DEDPM) by Mo(N-2,6-i-Pr2-C6H3)(CHCMe2Ph)(OCH(CH3)2)2. In the presence of quinuclidine, >96% 5-membered ring structures were realized at room temperature, e.g., using Mo(N-2,6- Me2-C6H3)(CHCMe2Ph)(OC(CH3)3)2. 4-(Ethoxycarbonyl)-4-(1S,2R,5S)-(+)-menthyl-1,6-heptadiyne was cyclopolymerized to determine the configuration of the double bond (i.e., the cis/trans ratio) and the tacticity of the poly(ene) backbone. Poly(4-(ethoxycarbonyl)-4-(1S,2R,5S)-(+)-menthyl-1,6- heptadiyne) again consisted of >96% 5-membered rings and possessed an all-trans tactic, presumably isotactic structure. A linear plot of number of monomers added (N) vs. molecular weight suggested that cyclopolymerization of DEDPM proceeded in a living manner. At least a class-V living system was confirmed by the stepwise synthesis of poly(DEDPM). Molecular weight distributions (PDIs) of 1.16-1.37 resulted from ratios of the rate constants for polymerization (kp) to initiation (k i), k p/k i >> 1. Influences of temperature, the base and steric and electronic effects of the arylimido and alkoxy ligand are presented. Complementary to the use of well-defined Schrock initiators, poly(DEDPM) containing exclusively 5-membered rings was accessible by the use of the quaternary systems MoCl5-n-Bu4Sn-EtOH-quinuclidine and MoOCl4-n-Bu4Sn-EtOH-quinuclidine. Though virtually identical polymers were obtained, the polymerization systems themselves were controlled, yet not living, as is the case with Schrock initiators. Selected polymer properties such as stability, degradation behavior, conductivity, and thermoresponsive behavior will be discussed. Finally, the polymerization behavior of other monomers such as N,N-dipropargylaniline (1), dipropargyl sulfide (2), 1,8-diethynylnaphthalene (3) and 1,2-diethynyltetramethyldisilane (4) is presented.

Polymerization of bis(3-trimethylsilyl-2-propynyl)ether and its copolymerization with diethyl dipropargylmalonate

The polymerization of a cyclopolymerizable disubstituted dipropargyl ether, bis(3-trimethylsilyl-2- propynyl)ether (BTPE), was attempted by various transition metal catalysts. The yield for the polymerization of BTPE was generally low, which is possibly due to the steric hindrance of bulky substituents. In general, the catalytic activities of Mo-based catalysts were found to be greater than those of W-based catalysts. The highest yield was obtained when the MoCl5-EtAlCl2 (1 : 2) catalyst system was used. The copolymerization of BTPE and diethyl dipropargylmalonate yielded a random copolymer with conjugated polymer backbone. However the polymers were partially desilylated, depending on the reaction conditions. The thermal and morphological properties of the resulting polymers were also discussed.

First Controlled Cyclopolymerization of Diethyl Dipropargylmalonate by MoCl5−n-Bu4Sn−EtOH−Quinuclidine and MoOCl4−n-Bu4Sn−EtOH−Quinuclidine To Give Highly Regular Polyenes Consisting Exclusively of 1,2-(Cyclopent-1-enylene)−Vinylene Units

Diethyl dipropargylmalonate (DEDPM) was cyclopolymerized by MoCl5−n-Bu4Sn−EtOH−quinuclidine (1:1:5:1) and MoOCl4−n-Bu4Sn−EtOH−quinuclidine (1:1:2:1), respectively, to produce poly(DEDPM) exclusively based on 1,2-(cyclopent-1-enylene)vinylene units (EtOH = ethanol). The exact ratio of five- to six-membered rings was determined by quantitative 13C NMR measurements. The initiator efficiency of MoOCl4−n-Bu4Sn−EtOH−quinuclidine (1:1:2:1) was as high as 91%, the highest value ever reported for such systems, whereas the efficiency for the corresponding MoCl5-based initiator was ≤67%. The absorption maximum λmax for poly(DEDPM) was 587 nm. A maximum effective conjugation length (Neff) of 49 was estimated therefrom. Molecular weights and polydispersity indices (PDIs) of the polymers were determined in CHCl3 by size exclusion chromatography (SEC) vs polystyrene (PS). Additionally, light-scattering (LS) data were collected at λ = 690 nm in order to calculate absolute molecular weights. Polydispersities ≤1.9 were obt...

Influence of chain length and temperature on UV-Vis absorption and degradation behavior of poly(diethyl dipropargylmalonate) with an alternating cis-trans-1,2-(cyclopent-1-enylene)vinylene structure

Cyclopolymerization of diethyl dipropargylmalonate (DEDPM) with Mo(N-2,6-i-Pr2-C6H3) (CHCMe2Ph)(OC(CH3)3)2 in the presence of quinuclidine yields poly(DEDPM) with an alternating cis-trans-1,2-(cyclopent-1-enylene)vinylene structure. Poly(DEDPM) n with different degrees of polymerization (n = 5–90) and PDI < 1.4 was prepared. A linear plot of number of monomers (N) added versus molecular weight as determined by light scattering (data were collected at λ = 690 nm) suggests that the cyclopolymerization of DEDPM proceeds in a living manner. A degree of polymerization (DP)-dependent UV-Vis absorption is found. At 25°C, the absorption maximum λmax for poly(DEDPM) n for n ≥ 50 is 591 nm. Thus, a maximum effective conjugation length N eff of 52 can be calculated. Increasing chain length results in a highly resolved fine structure in the UV-Vis spectrum with absorption maxima at 550 and 590 nm and a shoulder at around 513 nm for poly(DEDPM)70. In the solid state, absorption maxima were in the range of 478-574 nm for poly(DEDPM)5–90. Poly(DEDPM)10 and poly(DEPM)90 showed glass transition temperatures of 25.8 and 26.5°C, respectively. The measurement of λmax of poly(DEDPM)50 solutions in chloroform within a temperature range of 30°C reveals a reversible thermoresponsive behavior with changes in λmax of 8 nm. Poly(DEDPM) is stable under air over months in the solid state, as well as in solution using non-acidic solvents (e.g. CH2Cl2). In contrast, values for λmax for poly(DEDPM) solutions in CHCl3 decrease, if the solutions are exposed to air and light, yet remain constant in the absence of light and air. Changes in molar mass of poly(DEDPM) solutions in CHCl3 and CH2Cl2 were investigated by SEC measurements using light scattering detection and correlated with their time-dependent UV-Vis absorption behavior. Finally, poly(DEDPM)10–90 is thermally stable up to 185°C under a helium atmosphere.

Fine-Tuning of Molybdenum Imido Alkylidene Complexes for the Cyclopolymerization of 1,6-Heptadiynes To Give Polyenes Containing Exclusively Five-Membered Rings

Diethyl dipropargylmalonate (1) was cyclopolymerized by various well-defined molybdenum-based Schrock initiators to produce polymers exclusively based on 1,2-cyclopent-1-enylenvinylene units. For this purpose, variations in both the imido and alkoxy ligand in molybdenum alkylidene complexes of type Mo(NAr‘)(CHCMe2Ph)(OR)2 (Ar‘ = 2,6-i-Pr2C6H3; 2,6-Me2C6H3; OR = OCH(CF3)2, OCH(CH3)2, OC(CH3)3) were carried out. Polymers containing >95% 1,2-cyclopent-1-enylenvinylene units were obtained by low-temperature-initiated cyclopolymerization of 1 by Mo(N-2,6-i-Pr2C6H3)(CHCMe2Ph)(OCH(CH3)2)2 (2). In the presence of quinuclidine, >95% five-membered ring structures were realized at room temperature using Mo(N-2,6-Me2C6H3)(CHCMe2Ph)(OC(CH3)3)2 (3) and Mo(N-2,6-i-Pr2C6H3)(CHCMe2Ph)(OC(CH3)3)2 (4). In contrast, molybdenum initiators containing electron-withdrawing alkoxides such as Mo(N-2,6-Me2C6H3)(CHCMe2Ph)(OCH(CF3)2)2(quinuclidine) (5) or the nonfluorinated analogue Mo(N-2,6-Me2C6H3)(CHCMe2Ph)(OCH(CH3)2)2(quinuclidin...

CYCLOPOLYMERIZATION OF DIPROPARGYL DERIVATIVES BY Cp2MoCl2-EtAlCl2 CATALYST SYSTEM

ABSTRACT A Cp2MoCl2-EtAlCl2 catalyst system was used for the cyclopolymerization of various dipropargyl derivatives having different functionalities. These catalyst systems were found to be very effective for the polymerization of some dipropargyl monomers to give a relatively high yield of polymer. The polymerization behaviors were strongly dependent on the functionalities of dipropargyl monomers. The polymerization of such dipropargyl monomers as 1,6-heptadiyne, diphenyldipropargyl methane, diethyldipropargyl malonate, etc. proceeded well to give a quantitative yield, whereas this catalyst system was found to be less effective for the polymerization of dipropargyl monomers having perfluoroalkyl groups and quaternary ammonium salts. The polymer structure of the resulting polymers was characterized by various instrumental methods such as NMR, IR, and UV-visible spectroscopies to have a conjugated polyene backbone system with cyclic recurring units. The portion of 5- and 6-membered rings of the present conjugated cyclopolymer were also discussed.

Living Metathesis Polymerization of Diethyl Di-2-butynyl Malonate by Molybdenum-Based Ternary Catalysts

The living polymerization of diethyl di-2- butynyl malonate (DEDBM) was achieved with a MoOCl 4 -based ternary catalyst, MoOCl 4 -Bu 4 Sn-EtOH, to give a polymer with five- and six-membered rings in the main chain. In contrast, the polymerization of diethyl dipropargyl malonate (DEDPM) with the same catalyst led to gelation. Block copolymers were obtained from DEDBM and other substituted acetylenes such as 1-chloro-1-octyne. Poly(DEDBM) forms a condensed monomolecular membrane at the air-water interface.

Synthesis and characterization of novel crosslinkable polymers with a nonlinear optical chromophore as a pendant group

New crosslinkable polymers with a nonlinear optical (NLO) active chromophore as a pendant group were synthesized by condensation chain polymerization via palladium-catalyzed carbon–carbon coupling reactions. The polymerization yields were almost quantitative between the diiodobenzene (DIB) and diethyldipropargyl malonate (DEDPM) or 4-(dimethylamino)-4′-(6-dipropargylacetoxypropylsulfonyl)stilbene (DASS-6) monomers. To improve the molecular weight and mechanical properties of the NLO active polymer, we carried out the copolymerization with DIB and DASS-6 with various feed ratios of DEDPM. The resulting polymers were soluble in organic solvents and spun-cast onto indium tin oxide-coated glass substrates to make thin films. The molecular structures of the resulting polymers were characterized with various instrumental methods to confirm the carbon–carbon coupling reactions between the DIB and diacetylene monomers. The absorption of the ultraviolet–visible spectrum of the resulting polymers was drastically reduced after thermal curing at 160 °C because of the crosslinking of the reactive acetylene group in the polymer backbone. The electrooptic coefficient (r33) measured at 1.3 μm ranged from 7 to 15 pm/V. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4025–4034, 2001

Catalytic cyclopolymerization and copolymerization of 1,6-heptadiynes by Mo(CO)6

The catalytic polymerization of a series of 1,6-heptadiynes (1–4) by Mo(CO)6 under simple thermal conditions produces corresponding poly(1,6-heptadiyne)s with highly conjugated polyenes. The number-average molecular weights of the polymers range from 2400 to 110,000. The structures of the polymers depend on the types of monomers employed. Namely, diethyl dipropargylmalonate (DEDPM) and 1 result in a polyene backbone consisting of only five-membered rings, whereas the remaining monomers (2–4) result in a mixture of both five-membered and six-membered ring structures. The copolymerization of DEDPM and phenylacetylene (PA) can also be effected by the same catalysis to yield a polyene backbone consisting of only five-membered rings as well as PA. The relative molar ratio of the two monomers determines the yields and molecular weights of the copolymers. Comparative studies show that Mo(CO)6 exhibits reactivity toward DEDPM alone, thus initially catalyzing metathesis cyclopolymerization of DEDPM followed by copolymerization with PA. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2663–2670, 2000