Sample records for norbornadiene
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Gray, Victor; Lennartson, Anders; Ratanalert, Phasin; Börjesson, Karl; Moth-Poulsen, Kasper
2014-05-25
Red-shifting the absorption of norbornadienes (NBDs), into the visible region, enables the photo-isomerization of NBDs to quadricyclanes (QCs) to be driven by sunlight. This is necessary in order to utilize the NBD-QC system for molecular solar thermal (MOST) energy storage. Reported here is a study on five diaryl-substituted norbornadienes. The introduced aryl-groups induce a significant red-shift of the UV/vis absorption spectrum of the norbornadienes, and device experiments using a solar-simulator set-up demonstrate the potential use of these compounds for MOST energy storage.
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Low Molecular Weight Norbornadiene Derivatives for Molecular Solar-Thermal Energy Storage.
Quant, Maria; Lennartson, Anders; Dreos, Ambra; Kuisma, Mikael; Erhart, Paul; Börjesson, Karl; Moth-Poulsen, Kasper
2016-09-05
Molecular solar-thermal energy storage systems are based on molecular switches that reversibly convert solar energy into chemical energy. Herein, we report the synthesis, characterization, and computational evaluation of a series of low molecular weight (193-260 g mol(-1) ) norbornadiene-quadricyclane systems. The molecules feature cyano acceptor and ethynyl-substituted aromatic donor groups, leading to a good match with solar irradiation, quantitative photo-thermal conversion between the norbornadiene and quadricyclane, as well as high energy storage densities (396-629 kJ kg(-1) ). The spectroscopic properties and energy storage capability have been further evaluated through density functional theory calculations, which indicate that the ethynyl moiety plays a critical role in obtaining the high oscillator strengths seen for these molecules. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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Synthesis and Diels–Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers
Directory of Open Access Journals (Sweden)
Bilal Nişancı
2009-08-01
Full Text Available Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels–Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All compounds were characterized properly using NMR spectroscopy.
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Energy Technology Data Exchange (ETDEWEB)
Hautala, R.R.; Kutal, C.R.
1977-09-15
It was previously found that the triphenylcyclopropenyl-nickel compound ((C/sub 6/H/sub 5/)/sub 3/C/sub 3/Ni(CO)Br)/sub 2/ (I, X = Br) was an active catalyst for the conversion of quadricyclene to norbornadiene. This result was of considerable interest in connection with the development of the solar energy storage system since it indicated a new type of complex of a relatively abundant metal with potentially useful catalytic properties. For this reason, during this quarter a variety of triphenylcyclopropenyl-nickel derivatives were synthesized in order to determine their structure-activity relationships with respect to catalysis of the conversion of quadricyclene to norbornadiene. Also, a new approach to the development of a polymer-bound catalyst for the conversion of quadricyclene to norbornadiene based on an ion-exchange resin was also explored. Procedures and results are reported. (WHK)
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Reactivity and properties of dications generated by photoionization of 2,5-norbornadiene
Czech Academy of Sciences Publication Activity Database
Shaffer, Christopher; Schröder, Detlef; Roithová, J.; Zins, E. L.; Alcaraz, C.; Žabka, Ján; Polášek, Miroslav; Ascenzi, D.
2013-01-01
Roč. 336, Feb 15 (2013), s. 17-26 ISSN 1387-3806 R&D Projects: GA ČR GA203/09/1223; GA ČR GAP208/11/0446 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : dications * norbornadiene * photoionization * reactive monitoring * synchrotron radiation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.227, year: 2013
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Tinnemans, A.H.A.; Ouden, B. den; Mackor, A.; Bos, H.J.T.
1985-01-01
In this study, a series of acridinones and benzo-fused acridinones have been used for the first time as efficient photosensitizers for the norbornadiene-quadricyclane isomerization by near UV and visible iradiation. Their triplet energies (240-280 kJ · Mol-1) are well below the value of 290 kJ ·
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Theoretical study of the Diels-Alder reaction between o-benzoquinone and norbornadiene
Quijano-Quiñones, Ramiro F.; Quesadas-Rojas, M.; Cuevas, Gabriel; Mena-Rejón, Gonzalo J.
2013-06-01
The reaction between norbornadiene and o-benzoquinone is an important step in polyalicyclic rigid structures synthesis. It has been considered that this reaction is an example of Diels-Alder (DA) and hetero-Diels-Alder (HDA) cycloadditions with o-benzoquinone acting as diene (forming C-C bonds) and heterodiene (forming O-C bonds). We have performed a Density Functional Theory study of this reaction, employing B3LYP, mPW1PW91, and B1B95 functionals and 6-31G(d,p) and 6-31+G(d,p) Gaussian type basis sets. The results indicate that Diels-Alder is a feasible mechanism for both reactions, but should not be the main route to the formation of products with C-C bonds.
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Theoretical study of the Diels-Alder reaction between o-benzoquinone and norbornadiene
International Nuclear Information System (INIS)
Quijano-Quiñones, Ramiro F; Quesadas-Rojas, M; Mena-Rejón, Gonzalo J; Cuevas, Gabriel
2013-01-01
The reaction between norbornadiene and o-benzoquinone is an important step in polyalicyclic rigid structures synthesis. It has been considered that this reaction is an example of Diels-Alder (DA) and hetero-Diels-Alder (HDA) cycloadditions with o-benzoquinone acting as diene (forming C-C bonds) and heterodiene (forming O-C bonds). We have performed a Density Functional Theory study of this reaction, employing B3LYP, mPW1PW91, and B1B95 functionals and 6-31G(d,p) and 6-31+G(d,p) Gaussian type basis sets. The results indicate that Diels-Alder is a feasible mechanism for both reactions, but should not be the main route to the formation of products with C-C bonds.
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International Nuclear Information System (INIS)
Barnabas, M.V.; Trifunac, A.D.
1994-01-01
Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by γ-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations
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Directory of Open Access Journals (Sweden)
Ronald N. Warrener
2000-12-01
Full Text Available Ab initio and DFT quantum chemical calculations have been applied to a study of the Diels-Alder reaction of o-benzoquinone as diene and norbornadiene as dienophile. Transition states for the different reactions are located and activation energies estimated. The prefered exo-À-facial selectivity and exo,endo-stereoselectivity exhibited in this cycloaddition are readily predicted using RHF/3-21G or higher levels of calculations. Differences between experimentally observed results and calculations may be explained by the postulation of a second, nonconcerted biradical mechanism leading to formation of hetero Diels-Alder products.
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International Nuclear Information System (INIS)
Safronov, A.V.; Sokolova, M.N.; Vorontsov, E.V.; Petrovskij, P.V.; Barakovskaya, I.G.; Chizhevskij, I.T.
2004-01-01
New closo-(η 2 ,η 3 -(4-vinylcyclopentene-3-yl)rhodacarboranes were prepared by reaction of the complex [(η 4 -C 7 H 8 )RhCl] 2 (C 7 H 8 -norbornadiene) with salts of substituted nido-dicarbaundecaborates [K][nido-7-R 1 -8-R 2 -7,8-C 2 B 9 H 10 ] (R 1 =R 2 =H (a); R = R 2 =Me (b); R 1 , R 2 =1',2'-(CH 2 ) 2 C 6 H 4 (c); R 1 =Me, R 2 =Ph (d) in CH 2 Cl 2 . The structure of the compounds prepared in solution was studied by the method of multinuclear NMR spectroscopy. A probable mechanism of the norbornadiene ligand regrouping was suggested [ru
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Brummel, Olaf; Waidhas, Fabian; Bauer, Udo; Wu, Yanlin; Bochmann, Sebastian; Steinrück, Hans-Peter; Papp, Christian; Bachmann, Julien; Libuda, Jörg
2017-07-06
The two valence isomers norbornadiene (NBD) and quadricyclane (QC) enable solar energy storage in a single molecule system. We present a new photoelectrochemical infrared reflection absorption spectroscopy (PEC-IRRAS) experiment, which allows monitoring of the complete energy storage and release cycle by in situ vibrational spectroscopy. Both processes were investigated, the photochemical conversion from NBD to QC using the photosensitizer 4,4'-bis(dimethylamino)benzophenone (Michler's ketone, MK) and the electrochemically triggered cycloreversion from QC to NBD. Photochemical conversion was obtained with characteristic conversion times on the order of 500 ms. All experiments were performed under full potential control in a thin-layer configuration with a Pt(111) working electrode. The vibrational spectra of NBD, QC, and MK were analyzed in the fingerprint region, permitting quantitative analysis of the spectroscopic data. We determined selectivities for both the photochemical conversion and the electrochemical cycloreversion and identified the critical steps that limit the reversibility of the storage cycle.
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International Nuclear Information System (INIS)
Hart, H.; Cheng-Tai Peng
1982-01-01
The readily available benzodihydropentalene 6 and dimethyl acetylenedicarboxylate react to give norbornadiene diester 8, with a three-carbon bridge from C 1 to C 2 . Irradiation of 8 gives the corresponding C 1 -C 2 bridged quadricyclane diester 9, a new ring system. Diester 9 is quite stable, reverting to 8 with a tsub(1/2) of 30 min at 170 0 C. The corresponding diacid 11, also prepared, reverts to its norbornadiene precursor at a considerably lower temperature, possibly as a consequence of acid catalysis. (author)
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International Nuclear Information System (INIS)
Hoffmann, R.W.; Schuettler, R.; Marburg Univ.
1975-01-01
Thermal cleavage of spiro[norbornadiene-7,2'-oxiranes] respectively after 14 C labelling of the corresponding compound which was labelled by 14 C at the methylen-group, generates ketenes probably via carbenaoxiranes. An equilibration carbenaoxirane reversible oxirene could not be detected. (orig./HK) [de
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Effect of ethylene action inhibitors upon wound-induced gene expression in tomato pericarp
International Nuclear Information System (INIS)
Henstrand, J.M.; Handa, A.K.
1989-01-01
The contribution of wound-ethylene to wound-induced gene expression was investigated in unripe tomato pericarp using inhibitors of ethylene action. Wounded unripe tomato pericarp was treated with 2,5-norbornadiene or silver thiosulfate to inhibit specifically the induction of ethylene-dependent mRNA species. Poly(A) + RNAs isolated from these tissues after 12 hours of wounding were translated in vitro in a rabbit reticulocyte lysate system and [ 35 S]methionine-labeled polypeptides were compared to unwounded controls after separation by one and two-dimensional polyacrylamide gel electrophoresis. Results show that mechanical wounding induces a dramatic shift in gene expression (over 50 mRNA species) but expression of less than 15% of these genes is affected by the treatment with ethylene action inhibitors. A selective decrease in mRNAs coding for a 37 kilodalton doublet and 75 kilodalton polypeptides is observed in 2,5-norbornadiene and silver thiosulfate treated wounded pericarp. Levels of hydroxyproline-rich glycoprotein mRNAs induced in wounded tissue were not influenced by inhibitors of ethylene action
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International Nuclear Information System (INIS)
Yalçınkaya, Esra Evrim; Balcan, Mehmet; Güler, Çetin
2013-01-01
Polynorbornadiene clay nanocomposites were prepared for the first time by the ring opening metathesis polymerization (ROMP) using modified montmorillonite and polynorbornadiene the latter of which is used commonly in electric–electronic industry. The Na–MMT clay was modified by a quaternary ammonium salt containing Ruthenium complex as a suitable catalyst and intercalant as well. The norbornadiene monomers were polymerized within the modified montmorillonite layers by in-situ polymerization method in different clay loading degrees. Intercalation ability of the Ru catalyst and partially exfoliated nanocomposite structure were proved by powder X-ray Diffraction (XRD) Spectroscopy and Transmission Electron Microscopy (TEM) methods. The nanocomposite materials with high thermal degradation temperature and low dielectric constant compared to the pure polynorbornadiene were obtained. The dielectric constants decreased with the increase of the clay content. - Highlights: • Polynorbornadiene–clay nanocomposites were prepared for the first time. • Ruthenium complex was assigned as both suitable catalyst and intercalant. • The norbornadiene was polymerized by in-situ polymerization method. • Exfoliation/intercalation structures were found to be related with loading degree. • PNBD–MMT nanocomposites had a higher thermal degradation temperature and lower dielectric constant
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Schomaker, Jennifer M; Toste, F Dean; Bergman, Robert G
2009-08-20
The utility of cobalt dinitrosyl complexes for the [3 + 2] annulation of alkenes with unsaturated enones and ketimines has been demonstrated. Reaction of a series of cobalt dinitrosyl/alkene adducts with conjugate acceptors in the presence of Sc(OTf)(3)/LHMDS formed two new C-C bonds at the carbons alpha to the nitrosyl groups of the substrate, leading to unusual tri- and tetracycles. Retrocycloaddition of these products in the presence of norbornadiene yielded functionalized tetrasubstituted bicyclic olefins.
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Cobalt-Mediated [3+2]-Annulation Reaction of Alkenes with α,β-Unsaturated Ketones and Imines
Schomaker, Jennifer M.; Toste, F. Dean; Bergman, Robert G.
2009-01-01
The utility of cobalt dinitrosyl complexes for the [3+2] annulation of alkenes with unsaturated enones and ketimines has been demonstrated. Reaction of a series of cobalt dinitrosyl/alkene adducts with conjugate acceptors in the presence of Sc(OTf)3/LHMDS formed two new C-C bonds at the carbons α to the nitrosyl groups of the substrate, leading to unusual tri- and tetracycles. Retrocycloaddition of these products in the presence of norbornadiene yielded functionalized tetrasubstituted bicyclic olefins. PMID:19639989
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Theoretical Study of the Diastereofacial Isomers of Aldrin and Dieldrin
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Zoran Zdravkovski
2006-02-01
Full Text Available The Diels-Alder reaction of hexachlorocyclopentadiene with norbornadiene givesaldrin but theoretically three other diastereofacial isomers are possible. On oxidation theseisomers can generate eight adducts one of which is known as dieldrin. All these, as well asthe corresponding reactions with hexafluorocyclopenadiene were studied by semiempirical(AM1 and PM3 and hybrid density functional (B3LYP methods. Besides the energy levels,the transition states were calculated for the reactions leading to the diastereofacial isomers ofaldrin, which indicate that aldrin is the favored product of the reaction both fromthermodynamic and kinetic point of view.
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International Nuclear Information System (INIS)
Saini, H.S.; Consolacion, E.D.; Bassi, P.K.; Spencer, M.S.
1986-01-01
Application of exogenous ethylene in combination with gibberellic acid (GA 3 ), kinetin (KIN), and/or CO 2 has been reported to induce germination of lettuce seeds at supraoptimal temperatures. However, it is not clear whether endogenous ethylene also plays a mediatory role when germination under these conditions is induced by treatment regimes that do not include ethylene. Therefore, possible involvement of endogenous ethylene during the relief of thermoinhibition of lettuce (Lactuca sativa L. cv Grand Rapids) seed germination at 32°C was investigated. Combinations of GA 3 (0.5 millimolar), KIN (0.05 millimolar), and CO 2 (10%) were used to induce germination. Little germination occurred in controls or upon treatment with ethylene, KIN, or CO 2 . Neither KIN nor CO 2 affected the rate of ethylene production by seeds. Both germination and ethylene production were slightly promoted by GA 3 . Treatments with GA 3 + CO 2 , GA 3 + KIN, or GA 3 + CO 2 + KIN resulted in approximately 10- to 40-fold increases in ethylene production and 50 to 100% promotion of germination as compared to controls. Initial ethylene evolution from the treated seeds was greater than from the controls and a major surge in ethylene evolution occurred at the time of visible germination. Application of 1 millimolar 2-aminoethoxyvinyl glycine (AVG), an inhibitor of ethylene synthesis, in combination with any of above three treatments inhibited the ethylene production to below control levels. This was accompanied by a marked decline in germination percentage. Germination was also inhibited by 2,5-norbornadiene (0.25-2 milliliters per liter), a competitive inhibitor of ethylene action. Application of exogenous ethylene (1-100 microliters per liter) overcame the inhibitory effects of AVG and 2,5-norbornadiene on germination. The results demonstrate that endogenous ethylene synthesis and action are essential for the alleviation of thermoinhibition of lettuce seeds by combinations of GA 3 , KIN, and CO
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Saini, H S; Consolacion, E D; Bassi, P K; Spencer, M S
1986-08-01
Application of exogenous ethylene in combination with gibberellic acid (GA(3)), kinetin (KIN), and/or CO(2) has been reported to induce germination of lettuce seeds at supraoptimal temperatures. However, it is not clear whether endogenous ethylene also plays a mediatory role when germination under these conditions is induced by treatment regimes that do not include ethylene. Therefore, possible involvement of endogenous ethylene during the relief of thermoinhibition of lettuce (Lactuca sativa L. cv Grand Rapids) seed germination at 32 degrees C was investigated. Combinations of GA(3) (0.5 millimolar), KIN (0.05 millimolar), and CO(2) (10%) were used to induce germination. Little germination occurred in controls or upon treatment with ethylene, KIN, or CO(2). Neither KIN nor CO(2) affected the rate of ethylene production by seeds. Both germination and ethylene production were slightly promoted by GA(3). Treatments with GA(3)+CO(2), GA(3)+KIN, or GA(3)+CO(2)+KIN resulted in approximately 10-to 40-fold increases in ethylene production and 50 to 100% promotion of germination as compared to controls. Initial ethylene evolution from the treated seeds was greater than from the controls and a major surge in ethylene evolution occurred at the time of visible germination. Application of 1 millimolar 2-aminoethoxyvinyl glycine (AVG), an inhibitor of ethylene synthesis, in combination with any of above three treatments inhibited the ethylene production to below control levels. This was accompanied by a marked decline in germination percentage. Germination was also inhibited by 2,5-norbornadiene (0.25-2 milliliters per liter), a competitive inhibitor of ethylene action. Application of exogenous ethylene (1-100 microliters per liter) overcame the inhibitory effects of AVG and 2,5-norbornadiene on germination. The results demonstrate that endogenous ethylene synthesis and action are essential for the alleviation of thermoinhibition of lettuce seeds by combinations of GA(3), KIN
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1977-12-01
structures of these com- pounds are shown in Fig. 1, along with the abbreviations (HXX, XTHDCPD , etc.) by which they will be referred to in the...crystal because of the difficulty in obtaining good DSC data at the very low temperatures below the XTHDCPD melting point. The four NBD hydrogenated...estimated from the DSC fusion curve, was used for ACpf for XTHDCPD . The results of these calculations are shown in Fig. 3 as plots of Ti (in K and *F) versus
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The effect of ethylene on root growth of Zea mays seedlings
Whalen, M. C.; Feldman, L. J.
1988-01-01
The control of primary root growth in Zea mays cv. Merit by ethylene was examined. At applied concentrations of ethylene equal to or greater than 0.1 microliter L-1, root elongation during 24 h was inhibited. The half-maximal response occurred at 0.6 microliter L-1 and the response saturated at 6 microliters L-1. Inhibition of elongation took place within 20 min. However, after ethylene was removed, elongation recovered to control values within 15 min. Root elongation was also inhibited by green light. The inhibition caused by a 24-h exposure to ethylene was restricted to the elongating region just behind the apex, with inhibition of cortical cell elongation being the primary contributor to the effect. Based on use of 2,5-norbornadiene, a gaseous competitive inhibitor of ethylene, it was concluded that endogenous ethylene normally inhibits root elongation.
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Mansø, Mads; Petersen, Anne Ugleholdt; Wang, Zhihang; Erhart, Paul; Nielsen, Mogens Brøndsted; Moth-Poulsen, Kasper
2018-05-16
Molecular photoswitches can be used for solar thermal energy storage by photoisomerization into high-energy, meta-stable isomers; we present a molecular design strategy leading to photoswitches with high energy densities and long storage times. High measured energy densities of up to 559 kJ kg -1 (155 Wh kg -1 ), long storage lifetimes up to 48.5 days, and high quantum yields of conversion of up to 94% per subunit are demonstrated in norbornadiene/quadricyclane (NBD/QC) photo-/thermoswitch couples incorporated into dimeric and trimeric structures. By changing the linker unit between the NBD units, we can at the same time fine-tune light-harvesting and energy densities of the dimers and trimers so that they exceed those of their monomeric analogs. These new oligomers thereby meet several of the criteria to be met for an optimum molecule to ultimately enter actual devices being able to undergo closed cycles of solar light-harvesting, energy storage, and heat release.
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Ganguly, Gaurab; Sultana, Munia; Paul, Ankan
2018-01-18
Molecular solar thermal storage (MOST) systems have been largely limited to three classes of molecular motifs: azo-benzene, norbornadiene, and transition metal based fulvalene-tetracarbonyl systems. Photodimerization of anthracene has been known for a century; however, this photoprocess has not been successfully exploited for MOST purposes due to its poor energy storage. Using well-calibrated theoretical methods on a series of [n.n](9,10)bis-anthracene cyclophanes, we have exposed that they can store solar energy into chemical bonds and can release in the form of heat energy on demand under mild conditions. The storage is mainly attributed to the strain in the rings formed by the alkyl linkers upon photoexcitation. Our results demonstrate that the gravimetric energy storage density for longer alkyl-chain linkers (n > 3) are comparable to those for the best-known candidates; however, it lacks some of the deleterious attributes of known systems, thus making the proposed molecules desirable targets for MOST applications.
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Role of ethylene metabolism in Amaranthus retroflexus
International Nuclear Information System (INIS)
Raskin, I.; Beyer, E. Jr.
1989-01-01
14 C-Ethylene was metabolized by etiolated pigweed seedlings (Amaranthus retroflexus L.) in the manner similar to that observed in other plants. The hormone was oxidized to 14 CO 2 and incorporated into 14 -tissue components. Selected cyclic olefins with differing abilities to block ethylene action were used to determine if ethylene metabolism in pigweed is necessary for ethylene action. 2,5-Norbornadiene and 1,3-cyclohexadiene were effective inhibitors of ethylene action at 800 and 6400 μ1/1, respectively, in the gas phase, while 1,4-cyclohexadiene and cyclohexene were not. However, all four cyclic olefins inhibited the incorporation and conversion of 14 C-ethylene to 14 CO 2 by 95% with I 50 values below 100 μ1/1. The results indicate that total ethylene metabolism does not directly correlate with changes in ethylene action. Additionally, the fact that inhibition of ethylene metabolism by the cyclic olefins did not result in a corresponding increase in ethylene evolution, indicates that ethylene metabolism does not serve to significantly reduce endogenous ethylene levels
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Role of Ethylene in Lactuca sativa cv ;Grand Rapids' Seed Germination.
Abeles, F B
1986-07-01
Promotion of thermoinhibited (30 degrees C) lettuce (Lactuca sativa cv ;Grand Rapids') seed germination by ethylene is similar to the action of the gas in other hormonal systems. Ethylene was more active than propylene and ethane was inactive. An inhibitor of ethylene production, aminoethoxy-vinylglycine, reduced ethylene evolution and germination. Inhibitors of ethylene action such as, 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2,1,3-benzothiadiazole, 2,5-norbornadiene, and silver thiosulfate inhibited germination and the effect was reversed by the addition of ethylene to the gas phase. The action of ethylene appears to be due to the promotion of radial cell expansion in the embryonic hypocotyl. The action of N6-benzyladenine and fusiccocin, which also overcome thermoinhibition, appears to be due to a promotion of hypocotyl elongation. None of the germination promoters studied appeared to function by lowering the mechanical resistance of the endosperm to embryonic growth. Data presented here are consistent with the view that ethylene plays a role in lettuce seed germination under thermoinhibited and normal conditions.
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Ethylene-dependent effects on generative organ abscission of Lupinus luteus
Directory of Open Access Journals (Sweden)
Kamil Frankowski
2017-03-01
Full Text Available The abscission of certain organs from the plant is part of the fulfilment of its developmental programs. The separation process occurs in a specialized abscission zone usually formed at the base of detached organ. The changing level of phytohormones, particularly ethylene, is the element responsible for coordinating anatomical and physiological transformation that accompanies organ abscission. The application of ethylene (ET on Lupinus luteus stimulates flower abortion. However, the treatment with 1-aminocyclopropane-1-carboxylic acid (ACC – direct ET precursor – does not cause such a strong physiological response. In turn, when applied on the pedicels both ET biosynthesis (2-aminoethoxyvinylglycine; AVG and action (norbornadiene; NBD inhibitors reversed the stimulatory effect of ET on generative organ separation. In order to determine ET role in the flower abscission process in L. luteus, we identified the sequences coding for synthase (LlACS and oxidase (LlACO of ACC and measured their expression levels. Abscission zone activation is accompanied by a considerable increase both in LlACS and LlACO cDNAs and also ACC content, which is specifically localized in the dividing cells at the base of the flower being detached. Obtained results suggest that ET is a strong stimulator of flower abortion in L. luteus.
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Treatment of Plants with Gaseous Ethylene and Gaseous Inhibitors of Ethylene Action.
Tucker, Mark L; Kim, Joonyup; Wen, Chi-Kuang
2017-01-01
The gaseous nature of ethylene affects not only its role in plant biology but also how you treat plants with the hormone. In many ways, it simplifies the treatment problem. Other hormones have to be made up in solution and applied to some part of the plant hoping the hormone will be taken up into the plant and translocated throughout the plant at the desired concentration. Because all plant cells are connected by an intercellular gas space the ethylene concentration you treat with is relatively quickly reached throughout the plant. In some instances, like mature fruit, treatment with ethylene initiates autocatalytic synthesis of ethylene. However, in most experiments, the exogenous ethylene concentration is saturating, usually >1 μL L -1 , and the synthesis of additional ethylene is inconsequential. Also facilitating ethylene research compared with other hormones is that there are inhibitors of ethylene action 1-MCP (1-methylcyclopropene) and 2,5-NBD (2,5-norbornadiene) that are also gases wherein you can achieve nearly 100% inhibition of ethylene action quickly and with few side effects. Inhibitors for other plant hormones are applied as a solution and their transport and concentration at the desired site is not always known and difficult to measure. Here, our focus is on how to treat plants and plant parts with the ethylene gas and the gaseous inhibitors of ethylene action.
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Kato, M; Hayakawa, Y; Hyodo, H; Ikoma, Y; Yano, M
2000-04-01
1-Aminocyclopropane-1-carboxylate (ACC) synthase was rapidly induced in mesocarp tissue of Cucurbita maxima after wounding in the cut surface layer in 1 mm thickness (ca. 9 cells) (first layer) in both the enzyme activity and the levels of transcript. This led to a rapid accumulation of ACC and hence ethylene production. In the inside tissue (1-2 mm) (second layer), no significant induction of ACC synthase was observed, which resulted in a low level of ACC, although ethylene was evolved at a much lower rate than the first one. In contrast to ACC synthase, ACC oxidase was induced markedly in both the first and second layers and the development of its activity and the levels of mRNA remained high until later stages. It was considered that wound ethylene was closely associated with the development of ACC oxidase, since 2,5-norbornadiene (NBD), an inhibitor of ethylene action, substantially suppressed it. Phenylalanine ammonia-lyase (PAL) greatly increased in activity after wounding similarly to that of ACC synthase, in which increase in PAL activity occurred predominantly in the first layer. Induction of peroxidase activity after wounding had a close correlation in profile with that of ACC oxidase in that marked increases in the activity were observed in both the first and second layers and were strongly suppressed by NBD application. Four peroxidase isozymes were found by PAGE, among which a fraction was newly detected after wounding.
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Khan, A A; Huang, X L
1988-08-01
Relief of salt (0.1 molar NaCl) stress on germination of lettuce (Lactuca sativa L., cv Mesa 659) seeds occurred with applications of 0.05 millimolar kinetin (KIN) and 1 to 10 millimolar 1-aminocyclopropane 1-carboxylic acid (ACC). Treatment with KIN enhanced the pregermination ethylene production under saline condition. A synergistic or an additive enhancement of pregermination ethylene production and germination occurred under saline condition in the presence of KIN and a saturating dose (10 millimolar) of ACC. No KIN-ACC synergism was noted in ethylene production or germination under nonsaline condition. Addition of 1 millimolar aminoethoxyvinylglycine (AVG) inhibited the KIN-enhanced pregermination ethylene production (85 to 89%) and germination (58%) under saline condition but not the synergistic effect of KIN + ACC on ethylene production. Under nonsaline condition, AVG had no effect on germination even though ethylene production was strongly inhibited. Alleviation of salt stress by KIN was inhibited in a competitive manner by 2,5-norbornadiene (NBD) (0.02-0.2 milliliter per liter), and the addition of ACC and/or ethylene reduced this inhibition. An increase in the pregermination ethylene production and germination occurred also by cotylenin E (CN) under saline condition. However, neither AVG (1 millimolar) nor NBD (0.02 to 0.2 milliliter per liter) prevented the relief of salt stress by CN. Thus, KIN may alleviate salt stress on germination by promoting both ACC production and its conversion to ethylene. Rapid utilization of ACC may be the basis for the synergistic or the additive effect of KIN plus ACC. The need for ethylene production and action for the relief of salt stress is circumvented by a treatment with CN.
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Energy Technology Data Exchange (ETDEWEB)
Kanai, Y; Srinivasan, V; Meier, S K; Vollhardt, K P; Grossman, J C
2010-02-18
In the currently intensifying quest to harness solar energy for the powering of our planet, most efforts are centered around photoinduced generic charge separation, such as in photovoltaics, water splitting, other small molecule activation, and biologically inspired photosynthetic systems. In contrast, direct collection of heat from sunlight has received much less diversified attention, its bulk devoted to the development of concentrating solar thermal power plants, in which mirrors are used to focus the sun beam on an appropriate heat transfer material. An attractive alternative strategy would be to trap solar energy in the form of chemical bonds, ideally through the photoconversion of a suitable molecule to a higher energy isomer, which, in turn, would release the stored energy by thermal reversal. Such a system would encompass the essential elements of a rechargeable heat battery, with its inherent advantages of storage, transportability, and use on demand. The underlying concept has been explored extensively with organic molecules (such as the norbornadiene-quadricyclane cycle), often in the context of developing photoswitches. On the other hand, organometallic complexes have remained relatively obscure in this capacity, despite a number of advantages, including expanded structural tunability and generally favorable electronic absorption regimes. A highly promising organometallic system is the previously reported, robust photo-thermal fulvalene (Fv) diruthenium couple 1 {l_reversible} 2 (Scheme 1). However, although reversible and moderately efficient, lack of a full, detailed atom-scale understanding of its key conversion and storage mechanisms have limited our ability to improve on its performance or identify optimal variants, such as substituents on the Fv, ligands other than CO, and alternative metals. Here we present a theoretical investigation, in conjunction with corroborating experiments, of the mechanism for the heat releasing step of 2 {yields} 1 and