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Journal articles on the topic 'Isomeros meso'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

Jackson, W. Gregory. "Synthesis and Characterization of Simple Hydroxo- and Amido-Bridged Cobalt(III) Dinuclear Ions Missing from the Alfred Werner Collection." Australian Journal of Chemistry 62, no. 10 (2009): 1308. http://dx.doi.org/10.1071/ch09330.

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The unsymmetrical N,O-dibridging NO2– group in the threo (‘rac’) or erythro (‘meso’) isomers of [(en)2Co(μ-NH2,μ-NO2)Co(en)2]4+ is cleaved in hot triflic acid to yield a complex that is predominantly meso. This reacts in water to yield the new meso-[(en)2Co(μ-NH2,μ-OH)Co(en)2]4+ ion. The reactions of the threo- and erythro-μ-NO2– isomers in basic (0.1 M) aqueous solution are each retentive, giving the rac- and meso-[(en)2Co(μ-NH2,μ-OH)Co(en)2]4+ ions as products, respectively. The optically resolved erythro complex gives the achiral meso isomer, which completes the threo/rac and erythro/meso chemical correlations between the two series of dinuclear complexes; the meso synthesis completes the pair – the meso- and rac-[(en)2Co(μ-NH2,μ-OH)Co(en)2]4+ ions. In HCl, stable μ-Cl, μ-NH2 dinuclear ions are formed from these μ-NH2, μ-OH complexes, with retention. The peroxo or superoxo ions rac-[Co(en)2(μ-NH2,μ-O2)Co(en)2]n+ react with SnII to produce symmetrically bridged intermediates that decay to the common and new meso-[(en)2Co(μ-NH2,μ-OH)Co(en)2]4+ isomer on reaction in Me2SO. Both the rac and meso isomers of the μ-hydroxo-μ-peroxo complexes are also reduced by SnII to give intermediates that in Me2SO decay to the respective diols with retention. The new rac-[Co(en)2(μ-OH)2Co(en)2]4+ and meso-[(en)2Co(μ-NH2,μ-OH)Co(en)2]4+ isomers complete the characterization of rac/meso pairs in both systems. The corresponding μ-sulfate pairs are also reported.

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2

Fallon, GD, ML Felsbourg, KA Holland, and ID Rae. "Thermal Degradation of Polymers.II. Synthesis and Characterization of a Compound Which Models the Head-to-Head Linkage in Poly(Methyl Methacrylate)." Australian Journal of Chemistry 40, no. 3 (1987): 501. http://dx.doi.org/10.1071/ch9870501.

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As models for a poly(methyl methacrylate ) chain which contains a head-to-head unit, the (�)- and meso -isomers of tetramethyl 2,4,5,7-tetramethyloctane-2,4,5,7-tetracarboxylate have been synthesized by oxidative dimerization of a trimethylsilyl ketene acetal. The isomers were characterized by 1H and 13C n.m.r. spectroscopy, and the molecular structure of the meso -isomer was determined by X-ray crystallography. Molecular mechanics (MM2) calculations showed that three conformations of each isomer, about its central bond, had comparable steric energies. Calculated energy barriers to interconversion of the conformers were low.

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3

Searle, GH, and DA House. "The Isomers of the Bis(Diethylenetriamine)Chromium(III) and Bis[Di(3-Aminopropyl)Amine]Chromium(III) Cations, [Cr(Dien)2]3+ and [Cr(Dpt)2]3+: Preparation and Characterization." Australian Journal of Chemistry 40, no. 2 (1987): 361. http://dx.doi.org/10.1071/ch9870361.

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Addition of dien in slight excess to CrCl3.6H2O in Me2SO (which has been dehydrated at 190�C, then cooled to 170�) produces an isomeric mixture of orange-yellow [Cr( dien )2] Cl3.Me2SO of � approximate composition mer 70%; s- fac 30%; u- fac <2%. The isomers are partially separated by dissolving the mixture in 3M HCl and adding ZnCl2; pure lemon-yellow s- fac -[Cr( dien )2] (ZnCl5) then deposits. Addition of NaClO4 to the mother liquor results in the crystallizationof an orange-yellow mer/u-fac -[Cr( dien )2] (ClO4)3 (>98% mer ) mixture. All three isomers can be obtained as (Hg2Cl7)3- salts, suitable for single-crystal X-ray analysis, and the cation geometries have been established from these X-ray data. The mer and s- fac isomers are distinguished by their different labilities in acidic solution ( mer is relatively inert, s- fac decomposes rapidly), their different infrared and visible absorption spectra, and their different chromatographic behaviour on SP- Sephadex C-25. However, this latter technique failed to detect the u- fac form and was complicated by the facile decomposition of the s- fac isomer. The mer and s- fac forms isomerize rapidly in Me2SO and the equilibrium is largely towards the mer. [Cr( dpt )2]Cl3 [ dpt = di(3- aminopropyl )amine] could be obtained only by direct reaction between anhydrous CrCl3 and dpt , and was subsequently precipitated as the iodide and perchlorate salts. These consisted entirely of the mer isomer, from their isomorphism with the corresponding mer -[Cr( dpt )2 ]3+ salts. The six-membered rings in -[Cr( dien )2 ]3+ are considerably more resistant to hydrolytic decomposition than the rings in mer -[ cr ( dien )2]3+ and mer -[Co( dpt )2]3+.

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4

Fronczek, Frank R., Richard D. Gandour, Thomas M. Fyles, Philippa J. Hocking, Susan J. McDermid, and P. Daniel Wotton. "Polycarboxylate crown ethers from meso-tartaric acid." Canadian Journal of Chemistry 69, no. 1 (January 1, 1991): 12–19. http://dx.doi.org/10.1139/v91-003.

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The synthesis of crown ethers derived from meso-tartaric acid was investigated. The sodium salt of the bis(dimethylamide) of meso-tartaric acid reacted with diethylene glycol ditosylate to give a mixture of 18-crown-6 tetraamide and 27-crown-9 hexaamide crown ethers. The 2R,3S,11S,12R 18-crown-6 isomer crystallized in triclinic space group [Formula: see text] (a = 7.557(2), b = 8.866(2), c = 10.4133(13) Å, α = 94.13(2), β = 95.86(2), γ = 99.26(2)°, R = 0.040 for 2090 observed of 3129 unique reflections). The structures of the remaining products were then assigned from the NMR spectra. The solution conformations of the amide crown ethers were examined by NMR, and provide a rationale for the product distribution obtained. One of the 18-crown-6 isomers and a mixture of the two 27-crown-9 isomers were hydrolyzed to the respective crown ether carboxylic acids, and the stability constants for complexation of cations were determined by potentiometric titration. The meso tetra- and hexacarboxylates are remarkably nonselective and inefficient cation complexing agents, compared to related crown ethers from R,R-(+)-tartaric acid, due to the unfavorable conformational control exerted by the tartaro units. Key words: crown ether synthesis, complexation, crown ether conformation, meso-tartaric acid, crystal structure.

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5

Liu, Yingchun, Ted S. Sorensen, and Fang Sun. "Stereoselective 1,3-debromination reactions." Canadian Journal of Chemistry 71, no. 2 (February 1, 1993): 258–62. http://dx.doi.org/10.1139/v93-037.

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The metallate, PPN+Cr(CO)4NO−, was used for the 1,3-debrominative reductive cyclization of the (±) and meso isomers of dimethyl 2,4-dibromoglutarate and dimethyl 2,4-dibromo-2,4-dimethylglutarate. In both (±) isomers, the reaction is stereospecific in giving the trans cyclopropane product. In the meso case, the reaction is unselective in the first case, but distinctly favors the cis cyclopropane isomer in the second set of compounds. This (±) and meso pair thus represent the first example of near stereospecificity in the debrominations of both 1,3-dibromo diastereomers. Using an enantiomerically enriched dimethyl 2,4-dibromoglutarate, and determining the absolute stereochemistry of the cyclopropane product, it was found that a strict double inversion [Formula: see text] mechanism is involved in the (±) debromination reaction and presumably also in the near-stereospecific meso case reported above.

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6

Pronkin, Pavel, and Alexander Tatikolov. "Isomerization and Properties of Isomers of Carbocyanine Dyes." Sci 1, no. 1 (November 29, 2018): 5. http://dx.doi.org/10.3390/sci1010005.

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One of the important features of polymethine (cyanine) dyes is isomerization around one of C–C bonds of the polymethine chain. In this review, spectral properties of the isomers, photoisomerization and thermal back isomerization of carbocyanine dyes, mostly meso-substituted carbocyanine dyes, are considered. meso-Alkyl-substituted thiacarbocyanine dyes are present in polar solvents mainly as cis isomers and, hence, exhibit no photoisomerization, whereas in nonpolar solvents, in which the dyes are in the trans form, photoisomerization takes place. In contrast, the meso-substituted dyes 3,3′-dimethyl-9-phenylthiacarbocyanine and 3,3′-diethyl-9-(2-hydroxy-4-methoxyphenyl)thiacarbocyanine occur as trans isomers and exhibit photoisomerization in both polar and nonpolar solvents. The behavior of these dyes may be explained by the fact that the phenyl ring of the substituent in their molecules can be twisted at some angle, removing the substituent from the plane of the molecule and reducing its steric effect on the conformation of the trans isomer. In some cases, photoisomerization of cis isomers of meso-substituted carbocyanine dyes is also observed (for some meso-alkyl-substituted dyes complexed with DNA and chondroitin-4-sulfate; for 3,3′-diethyl-9-methoxythiacarbocyanine in moderate polarity solvents). The cycle photoisomerization–thermal back isomerization of cyanine dyes can be used in various systems of information storage and deserves further investigation using modern research methods.

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7

Pronkin, Pavel, and Alexander Tatikolov. "Isomerization and Properties of Isomers of Carbocyanine Dyes." Sci 1, no. 1 (November 29, 2018): 5. http://dx.doi.org/10.3390/sci1010005.v1.

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One of the important features of polymethine (cyanine) dyes is isomerization around one of C–C bonds of the polymethine chain. In this review, spectral properties of the isomers, photoisomerization and thermal back isomerization of carbocyanine dyes, mostly meso-substituted carbocyanine dyes, are considered. meso-Alkyl-substituted thiacarbocyanine dyes are present in polar solvents mainly as cis isomers and, hence, exhibit no photoisomerization, whereas in nonpolar solvents, in which the dyes are in the trans form, photoisomerization takes place. In contrast, the meso-substituted dyes 3,3′-dimethyl-9-phenylthiacarbocyanine and 3,3′-diethyl-9-(2-hydroxy-4-methoxyphenyl)thiacarbocyanine occur as trans isomers and exhibit photoisomerization in both polar and nonpolar solvents. The behavior of these dyes may be explained by the fact that the phenyl ring of the substituent in their molecules can be twisted at some angle, removing the substituent from the plane of the molecule and reducing its steric effect on the conformation of the trans isomer. In some cases, photoisomerization of cis isomers of meso-substituted carbocyanine dyes is also observed (for some meso-alkyl-substituted dyes complexed with DNA and chondroitin-4-sulfate; for 3,3′-diethyl-9-methoxythiacarbocyanine in moderate polarity solvents). The cycle photoisomerization–thermal back isomerization of cyanine dyes can be used in various systems of information storage and deserves further investigation using modern research methods.

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8

Pronkin, Pavel, and Alexander Tatikolov. "Isomerization and Properties of Isomers of Carbocyanine Dyes." Sci 1, no. 1 (March 20, 2019): 19. http://dx.doi.org/10.3390/sci1010019.

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One of the important features of polymethine (cyanine) dyes is isomerization about one of C–C bonds of the polymethine chain. In this review, spectral properties of the isomers, photoisomer-ization and thermal back isomerization of carbocyanine dyes, mostly meso-substituted carbocy-anine dyes, are considered. meso-Alkyl-substituted thiacarbocyanine dyes are present in polar solvents mainly as cis isomers and, hence, exhibit no photoisomerization, whereas in nonpolar solvents, in which the dyes are in the trans form, photoisomerization takes place. In contrast, the meso-substituted dyes 3,3′-dimethyl-9-phenylthiacarbocyanine and 3,3′-diethyl-9-(2-hydroxy-4-methoxyphenyl)thiacarbocyanine occur as trans isomers and exhibit photoisomerization in both polar and nonpolar solvents. The behavior of these dyes may be ex-plained by the fact that the phenyl ring of the substituent in their molecules can be twisted at some angle, removing the substituent from the plane of the molecule and reducing its steric ef-fect on the conformation of the trans isomer. In some cases, photoisomerization of cis isomers of meso-substituted carbocyanine dyes is also observed (for some meso-alkyl-substituted dyes com-plexed with DNA and chondroitin-4-sulfate; for 3,3′-diethyl-9-methoxythiacarbocyanine in moderate polarity solvents). The cycle photoisomerization–thermal back isomerization of cya-nine dyes can be used in various systems of information storage and deserves further investiga-tion using modern research methods.

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9

Yoshinaga, T., Y. Sudo, and S. Sano. "Enzymic conversion of α-oxyprotohaem IX into biliverdin IXα by haem oxygenase." Biochemical Journal 270, no. 3 (September 15, 1990): 659–64. http://dx.doi.org/10.1042/bj2700659.

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Conversion of four isomers of meso-oxyprotohaem IX into the corresponding biliverdin IX was attempted with a reconstituted haem oxygenase system in the presence of NADPH-cytochrome c reductase and NADPH. Only the alpha-isomer of meso-oxyprotohaem IX was converted effectively into biliverdin IX alpha, which was further reduced to bilirubin IX alpha by biliverdin reductase. Only trace amounts of biliverdins IX beta, IX gamma and IX delta were respectively formed from the incubation mixture of the corresponding oxyprotohaemin IX isomers with the complete haem oxygenase system under the same conditions. In a kinetic study, the Km for alpha-meso-oxyprotohaem IX was 3.6 microM, which was 2-fold higher than that for protohaem IX. The maximum velocity (Vmax.) of the conversion of alpha-meso-oxyprotohaem IX into biliverdin IX alpha was twice as fast as that of protohaem IX. These results demonstrate that alpha-meso-oxyprotohaem IX is an intermediate of haem degradation and it was converted stereospecifically into biliverdin IX alpha via verdohaem IX alpha.

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10

Marzilli, Luigi G., Lory Hansen, Andrew Taylor, and Rene Lachicotte. "Preparation and Crystal Structure of a Rhenium Analogue of the Cationic Renal Agent, Tc-99m Diaminocyclohexane." Metal-Based Drugs 7, no. 3 (January 1, 2000): 141–45. http://dx.doi.org/10.1155/mbd.2000.141.

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We report here a chemical study on a Re analogue of one of the few cationic Tc-99m tracers previously investigated as an agent for effective renal plasma flow (ERPF) measurement. Cationic Tc-99m tracers have the potential for overcoming problems associated with common anionic Tc-99m tracers in patients who have developed a uremic state. The Tc-99m-DACH tracer, prepared from 1,2-diaminocyclohexane (1,2-DACH), is the only cationic renal agent tested in humans and has seven possible isomers. The complex isolated from the reaction of the racemic mixture, (±)-trans-1,2-DACH, and ReIO2(PPh3)2 after conversion to the BPh4- salt was found by X-ray crystallography to be the meso isomer, trans-[ReO2 (trans-R,R-1,2-DACH)(trans-S,S-l,2-DACH)][BPh4]·MeOH·2H2O (1). The structural parameters for 1 are normal. The complex is highly symmetrical, suggesting that the analogous meso Tc-99m-DACH agent is also symmetrical. Studies of other Tc-99m-DACH agents that were made from cis-1,2-DACH or individual trans-1,2-DACH enantiomers show that the biodistribution is not very dependent on the starting 1,2-DACH ligand stereochemistry; these agents must be less symmetrical than the meso Tc-99m-DACH agent analogue of 1. Thus, the overall charge and lipophilicity (similar for all Tc-99m-DACH isomers) exert a greater influence on biodistribution than the specific structural features of the different Tc-99m-DACH isomers.

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11

McDonagh, Andrew M., Mark G. Humphrey, and David C. R. Hockless. "Preparation of cis- and trans-[OsCl2(Me2SO)4], and X-Ray Crystal Structures of the All-S-Bound Isomers." Australian Journal of Chemistry 51, no. 9 (1998): 807. http://dx.doi.org/10.1071/c98017.

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Efficient syntheses of the cis and trans isomers of [OsCl2(Me2SO)4] are reported. While a structural study of thetrans isomer confirms the spectroscopically assigned all-S-bound Me2SO configuration, a crystallographic determination of the cis isomer reveals a previously unheralded all-S-bound Me2SO geometry, in contrast to the spectroscopically inferred configuration predominant in solution which has one O-bound ligand. Fortrans-[OsCl2(Me2SO)4], crystals are tetragonal, space group I 4/m, with a 9·092(2), c 11·212(3) Å, Z 2, 566 unique reflections (34 parameters), converging at R 0·026 and Rw 0·032. For cis-[OsCl2(Me2SO)4], crystals are triclinic, space group P-1, with a 8·193(2), b 8·941(3), c 13·837(3) Å, α 79·77(2), β 79·91(2), γ 65·03(2)°, Z 2, 4152 unique reflections (173 parameters), converging at R 0·021 and Rw 0·018.

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12

Ball, Joanne M., P. Michael Boorman, and Kelly J. Moynihan. "Reactions of confacial bioctahedral ditungsten(III) species: Product distribution in reactions of the μ-hydrido-(bis-μ-dimethylsulfide)bis (trichlorotungstate(III)) ion, and trichlorotungsten(III)(μ-hydrido)bis((μ-dimethylsulfide)(dimethylsulfide)-dichlorotungsten(III) with benzyl bromide and bromide ion." Canadian Journal of Chemistry 68, no. 5 (May 1, 1990): 685–90. http://dx.doi.org/10.1139/v90-105.

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Reactions of compound Cl3W(μ-H)(μ-Me2S)2WCl2(Me2S), 1, and salts of derived chloro anion [Cl3W(μ-H)(μ-Me2S)2WCl3]−, 2, with bromide ion and with benzyl bromide are described. 1 was previously shown (1) to exist as a mixture of meso (C2v) and DL-pair (C1) of isomers, with the C2v isomer being the more stable. Displacement of the terminal dimethyl sulfide ligand of 1 by bromide ion results in the formation of the analogous isomers of ion [Cl3W(μ-H)(μ-Me2S)2WCl2Br]−, with retention of stereochemistry. The 1H NMR spectra of compounds in this series are uniquely informative as to the isomers present since the two environments of the methyl groups in the bridging dimethyl sulfide ligands (axial and equatorial) provide a probe for the ion stereochemistry. This is used to show that in reactions of 2 with benzyl bromide, after replacement of μ-H by Br, Br exchanges with terminal chlorides to give a mixture of isomers. Reactions of 1 with benzyl bromide are further complicated by the fact that both terminal dimethyl sulfide and μ-H are replaced by bromides which then redistribute over all possible terminal sites. Keywords: hydride, confacial bioctahedral complexes, tungsten, bromocarbons.

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13

Biswas, Foni B., Saswata Rabi, Kanak Barua, Tapashi G. Roy, Debashis Palit, and Benu K. Dey. "Zinc(II) complexes of 3,10-C-meso-2,5,5,7,9,12,12,14- octamethyl-1,8-diaza-4,11-diazoniacyclotetradecane as its bis(acetate) trihydrate, [LBH2][CH3COO]2.3H2O: Synthesis, Characterization and antimicrobial studies." European Scientific Journal, ESJ 14, no. 24 (August 31, 2018): 330. http://dx.doi.org/10.19044/esj.2018.v14n24p330.

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One isomeric ligand, LB among three isomers (LA, LB and LC) of 2,9- C-meso-2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecanes, differing in the orientation of methyl groups on the chiral carbon atoms) on interaction with vinyl acetate produces 2,9-C-meso-2,5,5,7,9,12,12,14- octamethyl-1,8-diaza-4,11-diazoniacyclotetradecane as its bis(acetate) trihydrate, [LBH2][OOCCH3]2.3H2O. This ligand salt trihydrate reacts with Zn(CH3COO)2.2H2O to produce square pyramidal monoacetatozinc(II) acetate complex [ZnLB(CH3COO)](CH3COO), which undergoes anion exchange reaction with NaClO4.6H2O to produce monoacetatozinc(II) perchlorate complex, [ZnLB(CH3COO)](ClO4). The complex, [ZnLB(CH3COO)](ClO4) undergoes axial substitution reactions with KSCN, NaNO2 and KNO3 to form the substitution products, [ZnLB(NCS)](NCS), [ZnLB(NO2)](ClO4) and [ZnLB(NO3)](ClO4) respectively where CH3COOis replaced by NCS- , NO3 - and NO2 - . All these complexes have been characterized on the basis of analytical, spectroscopic, conductometric and magnetochemical data. The antifungal and antibacterial activities of these compounds have been studied against some phytopathogenic fungi and bacteria.

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14

Kloubert, Tobias, Martin Schulz, Helman Görls, Manfred Friedrich, and Matthias Westerhausen. "Synthesis of 1,4-Diamino-2,3-di(2-pyridyl)butane and its Dinuclear Zinc(II) Chloride Complex." Zeitschrift für Naturforschung B 64, no. 7 (July 1, 2009): 784–92. http://dx.doi.org/10.1515/znb-2009-0702.

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In a Henry-type reaction nitromethane reacts with N-(2-pyridylmethylidene)-methylamine (1) yielding 1-methylamino-1-(2-pyridyl)-2-nitromethane (2) in nearly quantitative yield. This orange compound decomposes slowly in an inert gas atmosphere and fast in contact with air. Therefore 2 has to be stored at −78 ◦C as a methanol solution. Reduction of 2 with hydrogen in the presence of a Pd/C catalyst leads to the formation of 1,4-dinitro-2,3-di(2-pyridyl)butane (3) in the rather poor yield of 12 %. The major product is the meso-isomer, meso-3, whereas only traces of (R,R)- and (S,S)- isomers of 3 are formed. A conversion of the nitro groups into amino functionalities succeeds with hydrazine hydrate in the presence of a Pd/C catalyst yielding meso-1,4-diamino-2,3-di(2-pyridyl)butane (4). Recrystallization from an aqueous solution gives 4・2H2O. The zinc(II) chloride complex 5 with the metal atoms in distorted tetrahedral environments can be isolated after addition of two equivalents of ZnCl2 to 4. The molecular structures of trimeric 1, meso-3, (R,R)/(S,S)-3, meso-4, and 5 have been determined and are discussed.

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15

Thiele, Sven, Gerhard Erker, Cornelia Fritze, Christian Psiorz, and Roland Fröhlich. "Synthesis of a Chiral Meso-Like Ansa-Zirconocene Complex and its Use for the Catalytic Formation of Low Molecular Weight Polypropylene." Zeitschrift für Naturforschung B 50, no. 6 (June 1, 1995): 982–89. http://dx.doi.org/10.1515/znb-1995-0621.

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Reaction of lithium(neomenthylcyclopentadienid) 3 with dimethyldichlorosilane gives dimethylbis[3-(neomenthyl)cyclopentadienyl]silane 4 regioselectively as a mixture of double bond shift isomers (57% isolated). Deprotonation with 2 equiv. of butyllithium followed by treatment with zirconiumtetrachloride furnished a mixture of the three {dimethylsilylenbis[η5-3-(neomenthyl)cyclopentadienyl][zirconium dichloride diastereomers from which the pure meso-like isomer 6e [p -R (1′S ,3 ′R ,4 ′R),p -S (1′S ,3 ′R ,4 ′R)] was isolated by fractional crystallization. Complex 6 c was characterized by an X-ray crystal structure analysis. Its D 1 - Zr - D 2 angle of 126.8° is very similar as observed in bis(η-cyclopentadienyl) zirconium dichloride (D 1 and D 2 denote the centroids of the cyclopentadienyl rings). The homogeneous 6c/methylalumoxane Ziegler-type catalyst produces polypropylene of low molecular weight (Mη ≈ 670 at ambient temperature). Related catalyst systems may find interesting applications in organic synthesis.

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16

Punnagai, M., B.Sateesh, and G. Narahari Sastry. "A density functional theory study on the porphyrin isomers: Effect of meso-bridge length, relative stabilities, cis-trans isomerism." Arkivoc 2005, no. 3 (March 3, 2005): 258–83. http://dx.doi.org/10.3998/ark.5550190.0006.327.

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17

Stogniy, Marina Yu, Svetlana A. Erokhina, Irina D. Kosenko, Andrey A. Semioshkin, and Igor B. Sivaev. "Dimethyloxonium and Methoxy Derivatives of nido-Carborane and Metal Complexes Thereof." Inorganics 7, no. 4 (March 27, 2019): 46. http://dx.doi.org/10.3390/inorganics7040046.

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9-Dimethyloxonium, 10-dimethyloxonium, 9-methoxy and 10-methoxy derivatives of nido-carborane (9-Me2O-7,8-C2B9H11, 10-Me2O-7,8-C2B9H11, [9-MeO-7,8-C2B9H11]−, and [10-MeO-7,8-C2B9H11]−, respectively) were prepared by the reaction of the parent nido-carborane [7,8-C2B9H12]− with mercury(II) chloride in a mixture of benzene and dimethoxymethane. Reactions of the 9 and 10-dimethyloxonium derivatives with triethylamine, pyridine, and 3-methyl-6-nitro-1H-indazole result in their N-methylation with the formation of the corresponding salts with 9 and 10-methoxy-nido-carborane anions. The reaction of the symmetrical methoxy derivative [10-MeO-7,8-C2B9H11]− with anhydrous FeCl2 in tetrahydrofuran in the presence of t-BuOK results in the corresponding paramagnetic iron bis(dicarbollide) complex [8,8′-(MeO)2-3,3′-Fe(1,2-C2B9H10)2]−, whereas the similar reactions of the asymmetrical methoxy derivative [9-MeO-7,8-C2B9H11]− with FeCl2 and CoCl2 presumably produce the 4,7′-isomers [4,7′-(MeO)2-3,3′-M(1,2-C2B9H10)2]− (M = Fe, Co) rather than a mixture of rac-4,7′- and meso-4,4′-isomers.

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18

Bonnett, R., R. D. White, U. J. Winfield, and M. C. Berenbaum. "Hydroporphyrins of the meso-tetra(hydroxyphenyl)porphyrin series as tumour photosensitizers." Biochemical Journal 261, no. 1 (July 1, 1989): 277–80. http://dx.doi.org/10.1042/bj2610277.

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Four new hydroporphyrins [the o, m and p isomers of 5,10,15,20-tetra(hydroxyphenyl)chlorin and 5,10,15,20-tetra(m-hydroxyphenyl)bacteriochlorin] related to the tetra(hydroxyphenyl)porphyrins have been prepared. They show the expected strong absorption bands in the red region of the visible spectrum and are found to be very effective tumour photosensitizers.

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19

GOH, GERARD KIAN-MENG, and LESZEK CZUCHAJOWSKI. "The Synthesis of Isomeric Dithymidyl-phosphorus(V)-meso-tetraphenylporphyrins." Journal of Porphyrins and Phthalocyanines 01, no. 03 (July 1997): 281–85. http://dx.doi.org/10.1002/(sici)1099-1409(199707)1:3<281::aid-jpp32>3.0.co;2-l.

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The synthesis of three novel axial dinucleosides was successfully accomplished. The compounds are 5″- O , 5″- O -dithymidylphosphorus(V)-meso-tetraphenylporphyrin, 5″- O , 3″- O -dithymi-dylphosphorus(V)-meso-tetraphenylporphyrin, and 3″- O , 3″- O -dithymidylphosphorus(V)tetraphenylporo-phyrin. These compounds could provide a lead toward the synthesis of an oligo-porphyrinyl DNA analogue that represents a system containing phosphorus(V)porphine units axially connected through the 5″- O -thymidine-3″- O bridges.

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Goh, Gerard Kian‐Meng, and Leszek Czuchajowski. "The synthesis of isomeric dithymidyl‐phosphorus(V)-meso‐tetraphenylporphyrins." Journal of Porphyrins and Phthalocyanines 1, no. 3 (July 1997): 281–85. http://dx.doi.org/10.1002/(sici)1099-1409(199707)1:3<281::aid-jpp32>3.3.co;2-c.

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21

Mayans, Júlia, Mercè Font-Bardia, and Albert Escuer. "Na2MnIII6LnIII clusters with a non-equivalent core: chiral vs. meso isomerism." Dalton Transactions 49, no. 14 (2020): 4216–19. http://dx.doi.org/10.1039/d0dt00540a.

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Chiral and racemic clusters with the Na₂MnIII6Ln^III core and different coordination numbers around the Ln^III cation provide rare examples of symmetry dependent isomerism.

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22

Nardis, Sara, Giuseppe Pomarico, Federica Mandoj, Frank R. Fronczek, Kevin M. Smith, and Roberto Paolesse. "One-pot synthesis of meso-alkyl substituted isocorroles: the reaction of a triarylcorrole with Grignard reagent." Journal of Porphyrins and Phthalocyanines 14, no. 08 (August 2010): 752–57. http://dx.doi.org/10.1142/s1088424610002513.

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The reaction of 5,10,15-tritolylcorrole with EtMgBr opens the way for novel functionalizations of the corrole ring. DDQ oxidation of the macrocycle, followed by addition of the Grignard reagent, led to the formation of 5- and 10-alkyl substituted isocorroles in satisfying yields. Together with the one-pot formation of these isocorrole isomers, the use of such a nucleophile evidenced the competitive reactivity of the macrocycle β-positions, leading to the formation of 2-bromo- and 3-bromo-5,10,15-tritolylcorrole. While the formation of these monobromocorrole derivatives is not unprecedented, this is the first time the isomers have been separated and fully characterized. Furthermore, the higher yields of the 2-substituted species highlight a useful regioselectivity for the substitution reaction.

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23

Narayanan, Seenichamy Jeyaprakash, Sundararaman Venkatraman, Venkatara-manarao G. Anand, and Tavarekere K. Chandrashekar. "Meso-mesityl dithia- and diselenarubyrins: existence of planar and inverted forms in solution." Journal of Porphyrins and Phthalocyanines 06, no. 06 (June 2002): 403–9. http://dx.doi.org/10.1142/s1088424602000506.

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Syntheses, characterization and spectroscopic studies of meso-mesityl substituted rubyrins are reported. Specifically, it has been shown that these rubyrins behave differently from the meso-phenyl containing rubyrins in their structure. 1 H NMR studies reveal the existence of both planar and inverted isomers in solution in different ratios both in the freebase and protonated forms.

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24

Zhang, Beibei, Natasha M. Nesbitt, Pedro José Barbosa Pereira, and Wadie F. Bahou. "Biochemical characterization of biliverdins IXβ/δ generated by a selective heme oxygenase." Biochemical Journal 477, no. 3 (February 6, 2020): 601–14. http://dx.doi.org/10.1042/bcj20190810.

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The pro-oxidant effect of free heme (Fe2+-protoporphyrin IX) is neutralized by phylogenetically-conserved heme oxygenases (HMOX) that generate carbon monoxide, free ferrous iron, and biliverdin (BV) tetrapyrrole(s), with downstream BV reduction by non-redundant NADPH-dependent BV reductases (BLVRA and BLVRB) that retain isomer-restricted functional activity for bilirubin (BR) generation. Regioselectivity for the heme α-meso carbon resulting in predominant BV IXα generation is a defining characteristic of canonical HMOXs, thereby limiting generation and availability of BVs IXβ, IXδ, and IXγ as BLVRB substrates. We have now exploited the unique capacity of the Pseudomonas aeruginosa (P. aeruginosa) hemO/pigA gene for focused generation of isomeric BVs (IXβ and IXδ). A scalable system followed by isomeric separation yielded highly pure samples with predicted hydrogen-bonded structure(s) as documented by 1H NMR spectroscopy. Detailed kinetic studies established near-identical activity of BV IXβ and BV IXδ as BLVRB-selective substrates, with confirmation of an ordered sequential mechanism of BR/NADP+ dissociation. Halogenated xanthene-based compounds previously identified as BLVRB-targeted flavin reductase inhibitors displayed comparable inhibition parameters using BV IXβ as substrate, documenting common structural features of the cofactor/substrate-binding pocket. These data provide further insights into structure/activity mechanisms of isomeric BVs as BLVRB substrates, with potential applicability to further dissect redox-regulated functions in cytoprotection and hematopoiesis.

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Chang, Kai-Chi, Tsuyoshi Minami, Petr Koutnik, Pavel Y. Savechenkov, Yuanli Liu, and Pavel Anzenbacher. "Anion Binding Modes in meso-Substituted Hexapyrrolic Calix[4]pyrrole Isomers." Journal of the American Chemical Society 136, no. 4 (January 17, 2014): 1520–25. http://dx.doi.org/10.1021/ja411391c.

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26

Anand, Venkataramanarao G., Simi K. Pushpan, S. Venkatraman, Seenichamy Jeyaprakash Narayanan, Abhishek Dey, Tavarekere K. Chandrashekar, Raja Roy, Bhavani S. Joshi, S. Deepa, and G. Narahari Sastry. "30π Aromatic Meso-Substituted Heptaphyrin Isomers: Syntheses, Characterization, and Spectroscopic Studies." Journal of Organic Chemistry 67, no. 18 (September 2002): 6309–19. http://dx.doi.org/10.1021/jo025788d.

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27

Alexakis, Alexandre, Isabelle Aujard, and Pierre Mangeney. "Isomerization of meso Diamines into their C2 Symmetrical d,l Isomers." Synlett 1998, no. 8 (August 1998): 875–76. http://dx.doi.org/10.1055/s-1998-1791.

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28

Zheng, Yuxin, Yanze Huang, Peng Gao, Hongyan Liu, Suguru Murakami, Ryosuke Matsubara, and Masahiko Hayashi. "Regiodivergent Desymmetrization Reaction of meso-Azabicycloheptene Providing Two Enantioenriched Structural Isomers." Organic Letters 23, no. 7 (March 22, 2021): 2411–14. http://dx.doi.org/10.1021/acs.orglett.1c00036.

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29

Kvíčala, Jaroslav, Ondřej Baszczyňski, Alena Krupková, and Denisa Stránská. "Hydroboration of 1,1'-Bi(cyclopent-1-ene) and 3,3'-Biindene: Experimental and Theoretical Study." Collection of Czechoslovak Chemical Communications 71, no. 11-12 (2006): 1611–26. http://dx.doi.org/10.1135/cccc20061611.

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Hydroboration of bi(cyclopent-1-ene) (1) or 3,3'-biindene (2) with borane, thexylborane or (-)-isopinocampheylborane afforded, regardless of reaction conditions, meso-isomers of polycyclic 1,4-diols 3a, 4a as the main products. No reaction was observed with 9-BBN. The structure of the major product 4a, as well as of the minor racemic product 4b was assigned based on 1H NMR spectra of the corresponding Mosher's diesters 5a-5c. Finally, the stereochemistry of the product 4a was confirmed by a single-crystal X-ray analysis of the corresponding dimesylate 6. To elucidate preferential formation of the meso-isomers, complexes of monohydroborated intermediate with borane were studied theoretically by DFT methods.

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30

PAOLESSE, ROBERTO, ANTONELLA MACAGNANO, DONATO MONTI, PIETRO TAGLIATESTA, and TRISTANO BOSCHI. "Synthesis and Characterization of meso-Tetraphenylporphyrin-Corrole Unsymmetrical Dyads." Journal of Porphyrins and Phthalocyanines 02, no. 06 (November 1998): 501–10. http://dx.doi.org/10.1002/(sici)1099-1409(199811/12)2:6<501::aid-jpp89>3.0.co;2-m.

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Flat and gable meso-tetraphenylporphyrin-corrole heterodimers have been synthesized following a stepwise approach. The macrocyclic precursor for both isomers is a functionalized meso-tetraphenylporphyrin (TPP) bearing a formyl group at one of the peripheral phenyl groups. The preparation of these starting materials has been improved with respect to the previously reported method. Acidic condensation with pyrrole 8 allows the preparation of a TPP-dipyrromethane intermediate. Subsequent decarboxylation followed by reaction with formylpyrrole 2 affords the corresponding TPP–a,c-biladiene species. Final cyclization of this intermediate affords the desired heterodimer. Attempts to use the functionalized corrole 5 as starting material were unsuccessful, as this corrole failed to condense with pyrrole and benzaldehyde. This synthetic approach provides new examples of tetrapyrrolic heterodimers, which can represent useful biomimetic models to study photochemical processes.

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31

Sharifabad, Maneea Eizadi, Ben Hodgson, Mourad Jellite, Tim Mercer, and Tapas Sen. "Enzyme immobilised novel core–shell superparamagnetic nanocomposites for enantioselective formation of 4-(R)-hydroxycyclopent-2-en-1-(S)-acetate." Chem. Commun. 50, no. 76 (2014): 11185–87. http://dx.doi.org/10.1039/c4cc05358c.

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32

Silva, Ana M. G., Maria A. F. Faustino, Tânia M. P. C. Silva, Maria G. P. M. S. Neves, Augusto C. Tomé, Artur M. S. Silva, and José A. S. Cavaleiro. "NMR characterisation of five isomeric β,β′-diformyl-meso-tetraphenylporphyrins." J. Chem. Soc., Perkin Trans. 1, no. 15 (2002): 1774–77. http://dx.doi.org/10.1039/b203850a.

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33

Domingues, M. Rosário M., M. Graça O. S.-Marques, Pedro Domingues, M. Graça Neves, J. A. S. Cavaleiro, A. J. Ferrer-Correia, Olga V. Nemirovskiy, and Michael L. Gross. "Differentiation of positional isomers of nitro meso-tetraphenylporphyrins by tandem mass spectrometry." Journal of the American Society for Mass Spectrometry 12, no. 4 (April 2001): 381–84. http://dx.doi.org/10.1016/s1044-0305(01)00207-0.

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34

DURANTINI, EDGARDO N. "Synthesis of meso-nitrophenylporphyrins covalently linked to a polyphenylene chain bearing methoxy groups." Journal of Porphyrins and Phthalocyanines 04, no. 03 (April 2000): 233–42. http://dx.doi.org/10.1002/(sici)1099-1409(200004/05)4:3<233::aid-jpp200>3.0.co;2-h.

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A convenient procedure for the synthesis of polyphenylene porphyrin dyads is described. The dyads consist of a meso-nitrophenylporphyrin covalently linked to a polyphenylene chain by an amide bond. The final phenyl group in the chain bears electron donor methoxy groups. The π-conjugated chain was obtained in excellent yield via a Wittig–Horner reaction, which produces a new double bond (E isomer) incorporating either — COOCH 3 or E isomer) incorporating either — CON ( OCH 3)( CH 3) functional groups. Expansion of the conjugated chain involves the reduction of these groups to aldehydes followed by a second Wittig–Horner reaction. 5-(4-Aminophenyl)-10,15,20-tris(4-nitrophenyl)porphyrin was synthesized from meso-(4-nitrophenyl)dipyrromethane. The E isomer) incorporating either — NO 2 groups in para positions of the peripheral phenyl rings give extra electron-withdrawing character to the porphyrin macrocycles. Coupling of the polyphenylene acids with aminoporphyrin results in the desired dyads. These dyads have moieties with different electron donor–acceptor properties. This present strategy may be easily used for preparation of other similar dyad derivatives. These compounds can be suitable for photodynamic therapy.

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35

Samankumara, Lalith P., Matthias Zeller, Jeanette A. Krause, and Christian Brückner. "Syntheses, structures, modification, and optical properties of meso-tetraaryl-2,3-dimethoxychlorin, and two isomeric meso-tetraaryl-2,3,12,13-tetrahydroxybacteriochlorins." Organic & Biomolecular Chemistry 8, no. 8 (2010): 1951. http://dx.doi.org/10.1039/b924539a.

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36

Park, Juyeon, Ju‐Hyung Kim, Sunmi Bak, Kazukuni Tahara, Jaehoon Jung, Maki Kawai, Yoshito Tobe, and Yousoo Kim. "On‐Surface Evolution of meso ‐Isomerism in Two‐Dimensional Supramolecular Assemblies." Angewandte Chemie International Edition 58, no. 28 (July 8, 2019): 9611–18. http://dx.doi.org/10.1002/anie.201904290.

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37

Park, Juyeon, Ju‐Hyung Kim, Sunmi Bak, Kazukuni Tahara, Jaehoon Jung, Maki Kawai, Yoshito Tobe, and Yousoo Kim. "On‐Surface Evolution of meso ‐Isomerism in Two‐Dimensional Supramolecular Assemblies." Angewandte Chemie 131, no. 28 (June 5, 2019): 9713–20. http://dx.doi.org/10.1002/ange.201904290.

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38

Hubregtse, Ton, Huub Kooijman, Anthony L. Spek, Thomas Maschmeyer, Roger A. Sheldon, Isabel W. C. E. Arends, and Ulf Hanefeld. "Study on the isomerism in meso-amavadin and an amavadin analogue." Journal of Inorganic Biochemistry 101, no. 6 (June 2007): 900–908. http://dx.doi.org/10.1016/j.jinorgbio.2007.02.006.

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39

Bautista, Maria Teresa, Kelly Anne Earl, Patricia Anne Maltby, Robert Harold Morris, and Caroline Theresia Schweitzer. "New dihydrogen complexes: the synthesis and spectroscopic properties of iron(II), ruthenium(II), and osmium(II) complexes containing the meso-tetraphos-1 ligand." Canadian Journal of Chemistry 72, no. 3 (March 1, 1994): 547–60. http://dx.doi.org/10.1139/v94-078.

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The synthesis and properties of dihydrogen complexes trans-[MH(H2)L]+, M = Fe, Ru, Os, which contain the ligand meso-tetraphos-1, S,R-Ph2PCH2CH2P(Ph)CH2CH2P(Ph)CH2CH2PPh2 (L) are described. There are interesting possibilities of isomerism in such trans complexes because the axial binding sites at the metal are different, one being surrounded by four phenyl groups and the other by two phenyl groups. The osmium complex is prepared in an unusual reaction of cis-β-Os(Cl)2L with H2 (1 atm) and NaBPh4 (1 mol) in THF or by the reaction of trans-OsH(Cl)L with NaBPh4 and H2. The iron and ruthenium complexes were made by a reaction of HBF4 with complexes trans-M(H)2L that have inequivalent trans hydrides. The ruthenium complex was also prepared starting from isomers of trans-RuH(Cl)L. The H—H distance in the rapidly spinning dihydrogen ligand has been calculated from T1(min) data to be 0.88, 0.89, and 0.99 Å for the complexes of Fe, Ru, Os, respectively. The presence of the H—D bond in the isotopomers trans-[MH(HD)L]+ and trans-[MD(HD)L]+ is also confirmed by the observation of 1JHD coupling constants of 32, 33.5, and 26.4 Hz for Fe, Ru, and Os, respectively. There is no rapid intramolecular H atom exchange in these complexes in contrast to those with di-tert-phosphine ligands like [MH(H2)(dppe)2]+ or to the trihydride Re(H)3L. Described also are the properties of the precursor complexes including cis-β- and trans-Ru(Cl)2L and derivatives of the dihydrogen complexes trans-[MH(L′)L]+, L′ = CH3CN (on Ru and Os), PMe2Ph (on Ru), and CO (on Os). Trends in the NMR properties of isostructural complexes are reported.

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40

Motekaitis, Ramunas J., and Arthur E. Martell. "Stabilities of metal complexes of the meso and SS isomers of oxydisuccinic acid." Inorganic Chemistry 31, no. 1 (January 1992): 11–15. http://dx.doi.org/10.1021/ic00027a004.

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41

ALEXAKIS. A., ALEXAKIS A., I. AUJARD, and P. MANGENEY. "ChemInform Abstract: Isomerization of meso Diamines into Their C2 Symmetrical d,l Isomers." ChemInform 29, no. 47 (June 18, 2010): no. http://dx.doi.org/10.1002/chin.199847103.

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42

Kurtikyan, Tigran S., Astghik A. Hovhannisyan, Alexei Iretskii, and Peter C. Ford. "Reaction of the Five-Coordinate O-Nitrito Complex Fe(Por)(ONO) (Por = meso-tetra-arylporphyrinato) with THF Gives Two Six-Coordinate Isomers." Australian Journal of Chemistry 62, no. 10 (2009): 1226. http://dx.doi.org/10.1071/ch09318.

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The effect of the proximal ligand on the coordination of the nitrite ligand to the heme model systems Fe(Por)(η1-ONO) (Por = meso-tetraarylporphyrinato dianion) was investigated by FTIR and UV-vis spectra in solvent free, low temperature, porous layered solids and by density functional computations. The reaction of the five-coordinate complex Fe(Por)(η1-ONO) with the ether tetrahydrofuran gives a mixture of the O-nitrito and N-nitrito isomers Fe(Por)(THF)(η1-ONO) and Fe(Por)(THF)(NO2), respectively. This observation is in contrast to earlier studies with nitrogen donor Lewis bases where the N-nitrito isomers were clearly the more stable of the six-coordinated complexes. The adduct formation is reversible; the five-coordinate O-nitrito complexes Fe(Por)(η1-ONO) were largely restored upon warming under vacuum pumping.

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43

Perrier, Arnaud, Emmanuelle Mothes, Colin Bonduelle, and Geneviève Pratviel. "Synthesis of asymmetric guanidiniumphenyl-aminophenyl porphyrins." Journal of Porphyrins and Phthalocyanines 20, no. 12 (December 2016): 1438–43. http://dx.doi.org/10.1142/s1088424616501170.

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The symmetric meso-tetrakis(4-aminophenyl)porphyrin was reacted with nonstoichiometric amount of [Formula: see text],[Formula: see text]-bis(tert-butoxycarbonyl)-[Formula: see text]-methylisothiourea with respect to the amine functions of the porphyrin to afford (after deprotection of the Boc residues) the asymmetric guanidiniumphenyl-aminophenyl porphyrins carrying two or three guanidiniumphenyl substituents at the meso-position. The adjacent and opposite isomers of the bis(guanidiniumphenyl) modified porphyrins were isolated separately.

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44

Sekar, Govindasamy, Selvaraj Chandrasekar, and Iyyanar Karthikeyan. "Copper-Catalyzed Base-Controlled Diastereoselective Synthesis of Tetraarylethanes from 2-Benzylpyridines." Synthesis 50, no. 06 (December 11, 2017): 1275–83. http://dx.doi.org/10.1055/s-0036-1591846.

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A highly efficient and base-controlled diastereoselective synthesis of tetraarylethanes through copper-catalyzed dehydrogenative homocoupling of readily available 2-benzylpyridines is reported. Various dl- and meso-tetraarylethanes were diastereoseletively synthesized by this new protocol, where base plays the role of the principle modulator: Grignard reagents selectively provide the C2 isomers, whereas KOt-Bu promotes the formation of the meso-tetraarylethanes. Interestingly, the presence of excess KOt-Bu generates the (E)-tetraarylethenes as the only product.

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45

Ramabulana, Anza-Tshilidzi, Paul A. Steenkamp, Ntakadzeni E. Madala, and Ian A. Dubery. "Profiling of Altered Metabolomic States in Bidens pilosa Leaves in Response to Treatment by Methyl Jasmonate and Methyl Salicylate." Plants 9, no. 10 (September 27, 2020): 1275. http://dx.doi.org/10.3390/plants9101275.

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Bidens pilosa (Asteraceae) is an edible medicinal plant with many bioactivities reported to have a health-beneficial role in controling various diseases. Though B. pilosa contain a diverse array of natural products, these are produced in relatively low concentrations. A possible way to enhance secondary metabolite production can be through the use of elicitors. Here, the effects of exogenous treatments with two signal molecules—methyl jasmonate (MeJA) and methyl salicylate (MeSA)—on the metabolomic profiles of B. pilosa leaves were investigated. Plants were treated with 0.5 mM of MeJA or MeSA and harvested at 12 h and 24 h. Metabolites were extracted with methanol and separated on an ultra-high performance liquid chromatography system hyphenated to quadrupole time-of-flight mass spectrometry detection. Data was subjected to multivariate statistical analysis and modeling for annotation of metabolites. Hydroxycinnamic acid (HCA) derivatives, such as caffeoylquinic acids (CQAs), tartaric acid esters (chicoric acid and caftaric acid), chalcones, and flavonoids were identified as differentially regulated. The altered metabolomes in response to MeSA and MeJA overlapped to a certain extent, suggestive of a cross-talk between signaling and metabolic pathway activation. Moreover, the perturbation of isomeric molecules, especially the cis geometrical isomers of HCA derivatives by both treatments, further point to the biological significance of these molecules during physiological responses to stress. The results highlight the possibility of using phytohormones to enhance the accumulation of bioactive secondary metabolites in this plant.

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46

Faialaga, Nathan H., Satoru Ito, Hiroshi Shinokubo, Younghoon Kim, Kimoon Kim, and Ji-Young Shin. "A synthesis of novel expanded porphyrinoids: NiII-induced nitrile cyclization of dicyanovinylene-bis(meso-aryl)dipyrrin." Dalton Transactions 46, no. 33 (2017): 10802–8. http://dx.doi.org/10.1039/c7dt01838j.

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Ni^II-Metallation of dicyanovinylene-bis(meso-aryl)dipyrrin 1 under refluxed toulene conditions resulted in the formation of a bicyclic pyrrolizine ring to afford two isomeric bisNi^II expanded porphyrinoid complexes 2a and 2b, which exhibited typical features of aromatic porphyrinoids.

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47

Kim, Ajeong, Rashid Ali, Seok Ho Park, Yong-Hoon Kim, and Jung Su Park. "Probing and evaluating anion–π interaction in meso-dinitrophenyl functionalized calix[4]pyrrole isomers." Chemical Communications 52, no. 74 (2016): 11139–42. http://dx.doi.org/10.1039/c6cc04562f.

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48

Coles, Simon J., David B. Davies, Robert J. Eaton, Michael B. Hursthouse, Adem Kılıç, Robert A. Shaw, Şule Şahin, Aylin Uslu, and Serkan Yeşilot. "Stereogenic properties of 1,3-disubstituted derivatives of cyclotriphosphazene: cis (meso) and trans (racemic) isomers." Inorganic Chemistry Communications 7, no. 5 (May 2004): 657–61. http://dx.doi.org/10.1016/j.inoche.2004.01.012.

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49

Datta, Sudhin, and Abdelhadi Sahnoune. "MESO-PROPYLENE-CO-ETHYLENE POLYOLEFIN RUBBER: VULCANIZATION AND COMPARISON TO AMORPHOUS STEREOISOMER RUBBER." Rubber Chemistry and Technology 92, no. 1 (January 1, 2019): 43–50. http://dx.doi.org/10.5254/rct.18.81527.

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ABSTRACT A new class of polyolefin rubbers containing a majority of propylene copolymerized with ethylene and a vulcanizable, unsymmetrical diene is described. The key structural feature of these rubbers is the presence of meso-propylene sequences, which leads to a small level of crystallinity, which is amplified on uniaxial tensile deformation. This strain induced crystallization leads to very remarkable tensile and tear properties in sulfur and resin vulcanized formulations, even for very low viscosity compounds. Isomeric rubbers of a similar composition but with irregular propylene sequences, which are and stay amorphous on extension, are unremarkable in their vulcanized properties.

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50

Aojula, H. S., M. T. Wilson, and I. E. G. Morrison. "Functional consequences of haem orientational disorder in sperm-whale and yellow-fin-tuna myoglobins." Biochemical Journal 243, no. 1 (April 1, 1987): 205–10. http://dx.doi.org/10.1042/bj2430205.

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Ligand-binding kinetics of native and reconstituted sperm-whale myoglobin were studied in relation to haem orientational disorder by rapid kinetic methods. In addition, native yellow-fin-tuna myoglobin with significant amount of haem disorder was also used. The O2 dissociation and association rates were found for the proteins with different degrees of haem disorder, and these results suggest that the isomers are characterized by almost identical kinetic parameters. Rates of CO recombination after photolysis were also identical for the two orientational isomers. The results clearly indicate that the rotation of the haem about the alpha-gamma meso axis has little or no effect on the ligand-binding properties of these myoglobins.

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