Norbornadiene Moieties Research Articles

Mechanochemistry Enabled Inverse Vulcanization of Norbornadiene for Optical Polymers and Elastomeric Materials

The emergence of polymeric materials derived from elemental sulfur through inverse vulcanization has recently provoked great interest. Particularly, norbornadiene derived sulfur polymers are predicted to have high transmittance in the long-wave infrared region that can be an excellent candidate for polymeric IR optics. Moreover, owing to the unique cyclic structures of the norbornadiene moiety, it tends to form elastic material upon copolymerization with soft segments which has not been attained for elemental sulfur derived polymers. However, because of the volatility of norbornadiene (NBD) (boiling point is 89 °C), the chemicals could not bear the thermally induced inverse vulcanization process (T > 110 °C). Hence, in this work, for the first time, NBD is subjected to ball milling with elemental sulfur via solid mechanochemical induced inverse vulcanization, which successively affords poly(Sn-r-NBD) with a wide spectrum of sulfur content from 40 to 80 wt %. The synthesis is a green process that is solvent free and releases a traceless side product of H2S without heating. More importantly, the as-fabricated poly(Sn-r-NBD) displays superior transmittance (T > 40%) within the long-wave infrared region, which is obviously better than the most investigated poly(Sn-r-DIB). Furthermore, poly(Sn-r-NBD) derived polymeric material exhibits good elasticity. The present work not only demonstrates a facile and green methodology in fabricating norbornadiene derived sulfur polymers but also promotes the application of the sulfur polymer in high-performance IR optics and elastomeric materials.

Virtual screening of norbornadiene-based molecular solar thermal energy storage systems using a genetic algorithm.

We present a computational methodology for the screening of a chemical space of 1025 substituted norbornadiene molecules for promising kinetically stable molecular solar thermal (MOST) energy storage systems with high energy densities that absorb in the visible part of the solar spectrum. We use semiempirical tight-binding methods to construct a dataset of nearly 34000 molecules and train graph convolutional networks to predict energy densities, kinetic stability, and absorption spectra and then use the models together with a genetic algorithm to search the chemical space for promising MOST energy storage systems. We identify 15 kinetically stable molecules, five of which have energy densities greater than 0.45 MJ/kg, and the main conclusion of this study is that the largest energy density that can be obtained for a single norbornadiene moiety with the substituents considered here, while maintaining a long half-life and absorption in the visible spectrum, is around 0.55 MJ/kg.

New norbornadiene-tethered fulleropyrrolidines

N-Methyl-3,4-fulleropyrrolidine–norbornadiene conjugates with or without (CH2)n (n = 0–3) spacers were synthesized by the Prato reaction from the corresponding norbornadiene aldehydes. The influence of the spacer length on the diastereomer composition of the conjugates with two chiral centres studied by 13C NMR revealed a pronounced diastereotopic splitting of the fullerene carbon signals relating to four diastereomers in the case when the norbornadiene substituent was directly attached to the pyrrolidine moiety. When norbornadiene moiety was separated from the pyrrolidine one by three methylene units, the diastereotopic difference was lower and some of the signals were grouped.

Radical polymerization of 2,5‐norbornadienes containing ester groups by AIBN and oxygen gas

ABSTRACTNew 2,5‐norbornadiene‐type monomers bearing 1‐adamantyl and cyclohexyl ester groups on their 2‐position polymerized with azobisisobutyronitrile to form the polymers consisting of two types of polymer unit structures. The major part had a saturated nortricyclene framework, which was formed by 2,6‐addition along with intramolecular cyclization on the norbornadiene moiety. The minor part consisted of 2‐norbornene‐type units constructed via 2,3‐addition. A series of norbornadiene‐based monomers spontaneously polymerized in the presence of oxygen. Because a radical inhibitor, namely hydroquinone, could suppress this spontaneous reaction, it was indicated that the oxygen‐induced polymerization proceeds via free‐radical polymerization mechanism. Changing a quantity of provided oxygen gas (O2) to a norbornadiene monomer significantly affected on polymerization results, in specific, molecular weight of the formed polymer, which indicated that oxygen serves as one of the key reagents for the formation of free‐radical initiating species. It was proven that the combination of norbornadiene ethyl ester with O2 was applicable as a new free‐radical initiator for polymerization of methyl methacrylate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2528–2536

Photoresponsive polyamides containing pentamethylated norbornadiene moieties: Synthesis and photochemical properties under sunlight irradiation

Photoresponsive polyamides containing main-chain pentamethylated norbornadiene (NBD) moieties are obtained in quantitative yields via the Yamazaki-Higashi reaction between a pentamethylated NBD dicarboxylic acid and a series of aromatic diamines. Chemical structures are confirmed by 1 H and 13 C NMR and weight average molar masses measured by SEC are in the range of 21,500-28,600 g mol 21 with chain dis- persities close to 2. Physical properties are investigated by FTIR, differential scanning calorimetry (DSC), thermogravimet- ric analysis, and viscosimetry. All obtained polyamides are amorphous with glass transition temperatures ranging from 68 to 124 � C. They are soluble at room temperature in common organic solvents and exhibit good thermal stabilities with Td10 values ranging from 175 to 276 � C. The photochemical isomeri- zation of the NBD moiety into quadricyclane (QC) is studied by UV/vis spectroscopy after sunlight irradiation of polymer films. For all polyamides, a first-order kinetic rate is observed for the conversion of NBD to QC. The thermal release of the stored energy associated to the reverse transformation of QC groups into NBD ones is about 90-95 kJ mol 21 as measured by DSC of the irradiated polymer films. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 00, 000-000

Synthesis and photochemical properties of novel pentamethylated norbornadiene containing polyimides

A novel pentamethylated norbornadiene (NBD) based dianhydride, α,α′-bis-(3,4,5,6,7-pentamethylcyclopenta-2,4-dienyl)meta-xylene-1,2-dianhydride (3), was prepared from α,α′-bis-(pentamethylcyclopentadienyl)meta-xylene (1) and acetylene dicarboxylic acid. The bis-adduct formed via Diels–Alder reaction afforded tetra-acid (2), which was chemically cyclodehydrated to lead the targeted dianhydride (3). New polyimides containing NBD moieties in the main chain were prepared from the dianhydride monomer (3) and various aromatic diamines. The chemical structure of the polymers was confirmed by both 1H and 13C NMR analysis. Their Molecular weights were also measured by SEC. All of these polyimides are soluble at room temperature in common organic solvents, such as chloroform, dichloromethane, THF, DMSO, DMF, and NMP, and show good thermal stabilities. The photochemical isomerization of the NBD into quadricyclane (QC) was investigated by UV/vis spectrophotometry from polymer films using visible sunlight as irradiation source. It was found that the kinetic rate of the conversion NBD-QC which proceeded smoothly is a first kinetic order. The stored energies released by the transformation of QC groups into NBD ones of the irradiated polymer films were also evaluated by DSC measurement and were found to be around 90 kJ mol−1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

ChemInform Abstract: Synthesis and Photo Valence Isomerization of Polyamide Bearing Norbornadiene Unit.

Polyamides bearing norbornadiene (NBD) unit were prepared by the reaction of either bis(p-nitrophenyl) 2,3-NBD-dicarboxylate or a mixed anhydride bearing at the NBD moiety with various diamines. Films made of the polyamides indicated reversible UV-spectrum changes with UV irradiation, suggesting the occurrence of the photo-valence isomerization between the NBD and quadricyclane units.

Synthesis of novel β-dialkylamino-α,β-unsaturated trifluoromethylketones containing cyclobutene fragment and their reactions with organolithium and Grignard reagents

The highly reactive trifluoromethylenaminoketones, with a strained cyclobutene and norbornadiene moieties were firstly prepared from the corresponding β-halogeno-α,β-unsaturated trifluoromethylketones in almost quantitative yields. The ambident properties of these compounds in the reactions with organolithiums were discovered. The simple methods to control the selectivity of 1,2- or 1,4-addition of lithiated nucleophiles have been investigated.

Synthesis of self‐photosensitizing polyesters containing donor–acceptor norbornadiene moieties and benzophenone groups and their photochemical reactions

AbstractThe ring‐opening copolymerization of a glycidyl ester derivative having a benzophenone group and the donor–acceptor norbornadiene (D‐A NBD) dicarboxylic acid, 5‐(4‐methoxyphenyl)‐1,4,6,7,7‐pentamethyl‐2,5‐norbornadiene‐2,3‐dicarboxylic acid, monoglycidyl ester derivatives with D‐A NBD dicarboxylic anhydride using tetraphenylphosphonium bromide as a catalyst proceeded smoothly to give novel self‐photosensitizing NBD polymers in good yields. The molecular weight of these polyesters was about 4,000, and lower than that of analogous NBD polymers having no benzophenone group. All the synthesized NBD polymers isomerized smoothly to the corresponding quadricyclane (QC) polymers upon UV irradiation in tetrahydrofuran (THF) solution and in the film state. The rate of the photoisomerization of the D‐A NBD moieties in these polymers was higher than that of the D‐A NBD moieties in the polymer having no photosensitizing group. Furthermore, the rate of the photoisomerization of the D‐A NBD moieties in these polymers was also higher than that of the NBD polymer with low molecular weight photosensitizer in dilute solution. The photo‐irradiated polymers having QC moieties released thermal energies of 146–180 J/g. The D‐A NBD moieties contained in these NBD polymers possessed fair to good fatigue resistance. The degradation of the NBD moieties in these polymers was 15–30% after 50 repeated cycles of interconversion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2978–2988, 2007

Synthesis of new photoresponsive polyesters containing norbornadiene moieties by the ring‐opening copolymerization of donor–acceptor norbornadiene dicarboxylic acid anhydride with donor–acceptor norbornadiene dicarboxylic acid monoglycidyl ester derivatives

AbstractThe ring‐opening copolymerization of donor–acceptor norbornadiene (D–A NBD) dicarboxylic acid monoglycidyl ester derivatives with D–A NBD dicarboxylic acid anhydride was performed with tetraphenylphosphonium bromide as a catalyst in toluene to produce new norbornadiene (NBD) polyesters containing D–A NBD moieties in the main chain and in the side chain in one step in good yields. The photoisomerization of the D–A NBD moieties in these polyesters proceeded very smoothly to give the corresponding quadricyclane groups. Because these NBD polyesters contained many NBD moieties in the polymer chain, they had the highest capacity for heat storage in the D–A NBD polymers reported so far. The stored thermal energy of the irradiated polyesters was evaluated by differential scanning calorimetry analysis to be approximately 150–190 J/g. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4412–4421, 2005

New Large Refractive‐Index Change Materials: Synthesis and Photochemical Valence Isomerization of the Calixarene Derivatives Containing Norbornadiene Moieties.

We have examined the synthesis of cyclic oligomers with pendant norbornadiene (NBD) moieties based on the calixarenes [p-tert-butylcalix[8]arene (BCA), p-methylcalix[6]arene (MCA), )calix[4]resorcinarene (CRA), 2,8,14,20-tetra-decylcalix]4]resorcinarene (CRA 1 0 ), and 2,8,14,20-tetrakis(p-hydroxyphenyl)calix[4]resorcinarene (CRA p h )]. The photochemical valence isomerization of the obtained calixarene derivatives containing NBD moieties proceeded very smoothly to afford the corresponding quadricyclane (QC) moieties, and it was found that the large refractive-index changes (An's = 0.028-0.061) before and after photo-isomerization.

New Large Refractive-Index Change Materials: Synthesis and Photochemical Valence Isomerization of the Calixarene Derivatives Containing Norbornadiene Moieties

Abstract We have examined the synthesis of cyclic oligomers with pendant norbornadiene (NBD) moieties based on the calixarenes [p-tert-butylcalix[8]arene (BCA), p-methylcalix[6]arene (MCA), calix[4]resorcinarene (CRA), 2,8,14,20-tetradecylcalix[4]resorcinarene (CRA10), and 2,8,14,20-tetrakis(p-hydroxyphenyl)calix[4]resorcinarene (CRAph)]. The photochemical valence isomerization of the obtained calixarene derivatives containing NBD moieties proceeded very smoothly to afford the corresponding quadricyclane (QC) moieties, and it was found that the large refractive-index changes (Δn’s = 0.028–0.061) before and after photo-isomerization.

Synthesis of New Photoresponsive Polymers Containing Trifluoromethyl-Substituted Norbornadiene Moieties

Polymers containing trifluoromethyl (CF3)-substituted donor−acceptor NBD moieties in the side chain or in the main chain were synthesized by substitution or addition of a CF3−NBD−carboxylic acid derivative or by polycondensation of a CF3−NBD−dicarboxylic acid derivative. The photoisomerization of the NBD moieties in these polymers proceeded very smoothly to give the corresponding QC moieties. Furthermore, the NBD moieties exhibited efficient fatigue resistance.

Preparation of nano-sized silica with solar energy conversion and storage function by immobilization of norbornadiene moieties to hyperbranched poly(amido amine)-grafted nano-sized silica

The immobilization of norbornadiene (NBD) moieties onto nano-sized silica surface by the direct condensation of the surface terminal amino groups of hyperbranched poly(amido amine) (PAMAM)-grafted silica with 3-phenyl-2,5-norbornadiene-2-carboxylic acid is examined. It is found that the immobilization of NBD moieties onto the silica successfully proceeds in the presence of N,N′-dicyclohexylcarbodiimide (DCC) as a condensing agent. The immobilized NBD moieties onto the silica surface increases with increasing amount of amino groups of hyperbranched PAMAM-grafted silica, but the percentage of amino groups used for the immobilization of NBD moieties is decreased. The immobilized NBD moieties on the silica surface are readily isomerized to quadricyclane (QD) by photo-irradiation in n-hexane. Stored thermal energy by QD-immobilized silica is released as thermal energy by heating. The stored thermal energy of QD-immobilized silica increases with progress of the photo-irradiation time and became constant, about 30 J/g-silica, after 2 h.

Synthesis of New Photoresponsive Polymers Containing Trifluoromethyl-Substituted Norbornadiene Moieties

Abstract Polymers containing trifluoromethyl (CF3)-substituted donor−acceptor NBD moieties in the side chain or in the main chain were synthesized by substitution or addition with CF3-NBD-carboxylic acid derivatives, or by polycondensation of CF3-NBD-dicarboxylic acid derivatives, and the durability of the resulting polymers was examined.

Synthesis of polyethers with unsymmetrical structures by the polyaddition of 3‐ethyl‐3‐(glycidyloxymethyl)oxetane with diacyl chlorides

Polyethers with unsymmetrical structures in the main chains and pendant chloromethyl groups were synthesized by the polyaddition of 3-ethyl-3-(glycidyloxymethyl)oxetane (EGMO) with certain diacyl chlorides with quaternary onium salts or pyridine as catalysts. The unsymmetrical polyaddition of EGMO containing two different cyclic ether moieties such as oxirane and oxetane groups with terephthaloyl chloride proceeded smoothly in toluene at 90 °C for 6 h to give polymer 1 with a number-average molecular weight (Mn) of 51,700 in a 93% yield when tetrabutylammonium bromide (TBAB) was used as a catalyst. The polyaddition also proceeded smoothly under the same conditions when other quaternary onium salts, such as tetrabutylammonium chloride, tetrabutylammonium iodide, tetrabutylphosphonium chloride, and tetrabutylphosphonium bromide, and pyridine were used as catalysts. However, without a catalyst no reaction occurred under the same reaction conditions. Polyadditions of EGMO with isophthaloyl chloride and adipoyl chloride gave polymer 2 (Mn = 28,700) and polymer 3 (Mn = 25,400) in 99 and 65% yields, respectively, under the same conditions. The chemical modification of the resulting polymer, polymer 1, which contained reactive pendant chloromethyl groups, was also attempted with potassium 3-phenyl-2,5-norbornadiene-2-carboxylate with TBAB as a phase-transfer catalyst, and a polymer with 65 mol % pendant norbornadiene moieties was obtained. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 368–375, 2001

Diastereoselective addition of monoterpenic alcoholates and thiolates to 2,3-dicarbomethoxynorbornadiene

Addition of excess lithium salts of (−)-menthol or (−)-borneol to 2,3-dicarbomethoxynorbornadiene 1 affords the transesterification–addition products 4 and 5. The thiols derived from the same monoterpenes give only the addition products to the activated double bond, 6 and 7. In all cases, the addition reaction is totally exo-selective with respect to the norbornadiene moiety and moderately selective in discriminating the si- and re-face of the double bond. Both diastereomeric products are formed as a mixture of endo–exo epimers at C3. The major addition product of (−)-menthol to 1 is crystalline, of known absolute configuration, and has potential as a precursor of chiral ligands.

主鎖に二置換アミド型ノルボルナジエン構造を有するポリ（エステル／アミド）の物性とその耐候性

主鎖に二置換アミド型ノルボルナジエン(NBD)構造を有するポリ(エステル/アミド)(P-1)の耐候性とその向上について検討を行った。P-1のフィルム状態での屋外暴露試験を行った結果,暴露期間の経過とともに蓄熱量が減少し,架橋反応や主鎖の切断が起ることが判明した。一方,P-1フィルム表面をポリビニルアルコール(PVA)フィルムで保護した試料について同様に屋外暴露試験を行った結果,PVAで保護することにより蓄熱量の減少が抑制され,P-1フィルムの耐候性を向上させることが可能であることが明らかとなった。また,P-1に光安定剤を添加し,同様に耐候性の検討を行った結果,暴露90日までは,蓄熱量の減少は見られず,P-1フィルムの光-熱変換機能が安定に作用することがわかった。さらに,P-1をガラス板で保護した場合にも耐候性の向上が認められた。以上のことから,NBDポリマーの表面を保護すること,および光安定剤を添加することにより,NBDポリマーの耐候性が効果的に向上することが判明した。

Synthesis of Self-Photosensitizing Polyesters Carrying Pendant Norbornadiene (NBD) Moieties and Benzophenone Groups and Their Photochemical Reactions

Various epoxy monomers containing benzophenone (BP) groups were synthesized by reactions of potassium or lithium salts of BP derivatives with excess epichlorohydrin or epibromohydrin using tetrabutylammonium bromide (TBAB) as a phase transfer catalyst (PTC). The copolymerization of glycidyl 3-(piperidylcarbonyl)-2,5-norbornadiene-2-carboxylate (GPNC), which was prepared by the reaction of epichlorohydrin with potassium carboxylate of a norbornadiene (NBD) derivative using a PTC, and (glycidyloxy)benzophenone with phthalic anhydride (PAn) proceeded in 93% yield using TBAB as a catalyst in sulfolane at 100 °C for 24 h to give self-photosensitizing polyester P-1 containing a pendant NBD moiety and a pendant 4-oxybenzophenone group. Copolymerizations of various epoxy monomers containing certain NBD moieties and BP groups with PAn produced corresponding polyesters with pendant NBD moieties and BP groups in good yields. The photochemical valence isomerizations of the NBD moieties and the photosensitizing isomerizations of the NBD moieties due to the energy transfer from excited BP groups to the NBD moieties in the polymers were performed in the film state or in dichloromethane solution. From this result, it was found that rates of the photochemical isomerization of the NBD moieties in the polymers were strongly enhanced by the introduction of the pendant BP, N-alkyl-N,N‘,N‘-trimethyl-4,4‘-diaminobenzophenone (TBP), group. Furthermore, the photochemical isomerization of the NBD moieties in the polymers having a pendant TBP group proceeded effectively in a diluted dichloromethane solution compared with the mixtures of NBD polymers and low molecular weight photosensitizers such as 4,4‘-bis(N,N-diethylamino)benzophenone. Glass transition temperatures (Tg's) of the prepared polyesters having NBD moieties and stored thermal energy in the corresponding quadricyclane (QC) residues in the polymers were measured by DSC analysis. Then, it was found that Tg's of NBD polyesters were 30−85 °C, and photoirradiated polyesters having QC residues released their stored thermal energies (about 90 kJ/mol) at temperatures above the Tg's of the corresponding NBD polymers.

Large photoinduced refractive index changes of a polymer containing photochromic norbornadiene groups

We prepared a polymer containing pendant norbornadiene (NBD) moieties, P(MMA0.43-co-GMA0.57-PNCA), and measured absorbance and refractive index spectra before and after photoisomerization of norbornadiene moieties. Large photoinduced refractive index changes of ∼0.01 were obtained at 632.8 nm, the region far from the absorption band. A quantum yield of 0.50 was obtained for the photoisomerization of NBD moieties in this polymer. These values are sufficient to make efficient channel waveguides by photoisomerization.