Multiple‐State Emissions from Neat,Single‐Component Molecular Solids: Suppression of Kasha's Rule

Three rigid and structurally simple heterocyclic stilbene derivatives, (E)‐3H,3′H‐[1,1′‐biisobenzofuranylidene]‐3,3′‐dione, (E)‐3‐(3‐oxobenzo[c] thiophen‐1(3H)‐ylidene)isobenzofuran‐1(3H)‐one, and (E)‐3H,3′H‐[1,1′‐bibenzo[c] thiophenylidene]‐3,3′‐dione, are found to fluoresce in their neat solid phases, from upper (S₂) and lowest (S₁) singlet excited states, even at room temperature in air. Photophysical studies, single‐crystal structures, and theoretical calculations indicate that large energy gaps between S₂ and S₁ states (T₂ and T₁ states) as well as an abundance of intra and intermolecular hydrogen bonds suppress internal conversions of the upper excited states in the solids and make possible the fluorescence from S₂ excited states (phosphorescence from T₂ excited states). These results, including unprecedented fluorescence quantum yields (2.3–9.6 %) from the S₂ states in the neat solids, establish a unique molecular skeleton for achieving multi‐colored emissions from upper excited states by “suppressing” Kasha's rule.     

Synthesis of 3,3′-(1,6-hexanediyl)bis-pyrimidine derivatives and 3,4-dithia[6.6](1.3)pyrimidinophane

Several 3,3′-(1,6-hexanediyl)bis[6-methyl-2,4(1H,3H)-pyrimidinedione] derivatives ( 4a, 4b , and 4c ) were synthesized from 1,6-(hexanediyl)bis[6-methyl-2H-1,3-oxazine-2,4(3H)-dione] (3) . Compound 4c was converted to 6, which reacted with thiourea giving thiuronium salt 7 . 3,3′-(1,6-Hexanediyl)bis [1-(2-mercaptoethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione] (9) was obtained by the hydrolysis of 7 , and then 9 was oxidized to 12,22-dimethyl-3,4-dithia[6.6] (1.3)-1,2,3,4-tetrahydro-2,4-dioxopyrimidinophane (10) .     

Synthesis and Properties of Brominated 6,6'-Dimethyl-[2,2'-bi-1H-indene]-3,3'-diethyl-3,3'-dihydroxy-1,1 '-diones

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 2 ), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 3 ) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 4 ) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 1 ). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4 , molecular arrangement is defective tightness compared with its precursor 1 . Besides, UV‐Vis absorption spectra in CH₂Cl₂ solution, photochromic and photomagnetic properties in solid state of 2 , 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.     

The Behavior of 3,3-Diphenylindan-1,2-dione Towards Phosphonium Ylides

The reaction of alkoxycarbonyl- and cyanomethylene(triphenyl)phosphoranes with 3,3-diphenylindan-1,2-dione in dry benzene at room temperature for about 5 h led to the formation of a mixture of (E)- and (Z)-diastereomers. On the other hand, treatment of the dione with acetylmethylene(triphenyl)phosphorane afforded a mixture of (E)-3,3-diphenyl-1-(2-oxo-2-methylethylidene)indan-2-one and unexpected product (E)-3-(3,3-diphenyl-2-oxoindan-1-ylidene)-4-(triphenyl-λ⁵-phosphanylidene)hexane-2,5-dione, whereas with benzoylmethylene(triphenyl)phosphorane gave a mixture of (E)-3,3-diphenyl-1-(2-oxo-2-phenylethylidene)indan-2-one, [(2R ^*,3S ^*)-3-benzoyl-8,8-diphenyl-3,8-dihydro-2H-indeno{2,1-b}furan-2-yl]phenylmethanone and 1,4-diphenyl-2-(3,3-diphenyl-2-hydroxy-3H-inden-1-yl)but-2-ene-1,4-dione. The reaction mechanisms are considered and structural assignments of the new compounds are based on spectroscopic evidence. The molecular structures of the two diastereomers and the unexpected product were elucidated by X-ray crystallography.     

Synthese von optisch aktiven,natürlichen Carotinoiden und strukturell verwandten Naturprodukten. VIII. Synthese von (3S,3′S)-7,8,7′,8′-Tetradehydroastaxanthin und (3S,3′S)-7,8-Didehydroastaxanthin (Asterinsäure)

Synthesis of Optically Active Natural Carotenoids and Structurally Related Compounds. VIII. Synthesis of (3S,3′S)-7,8,7′,8′-Tetradehydroastaxanthin and (3S,3′S)-7,8-Didehydroastaxanthin (Asterinic Acid) The synthesis of all-trans-(3S,3′S)-3,3′-dihydroxy-7,8, 7′,8′-tetradehydro-β, β-carotene-4,4′-dione ( 1 ), of all-trans-(3S,3′S)-3,3′-dihydroxy-7, 8-didehydro-β,β-carotene-4,4′-dione ( 2 ) (asterinic acid = mixture of 1 and 2 ), and of their 9,9′-di-cis- and 9-cis-isomers is reported starting from (4′S)(2E)-5-(4′-hydroxy-2′, 6′,6′-trimethyl-3′-oxo-l′-cyclohexenyl)-3-methyl-2-penten-4-ynal ( 8 ). The absolute configuration (3S,3′S) for both components 1 and 2 of asterinic acid ex Asterias rubens is confirmed on the basis of spectroscopic and direct comparison.     

The Behavior of 3,3-Diphenylindan-1,2-dione Towards Phosphonium Ylides

Summary. The reaction of alkoxycarbonyl- and cyanomethylene(triphenyl)phosphoranes with 3,3-diphenylindan-1,2-dione in dry benzene at room temperature for about 5 h led to the formation of a mixture of (E)- and (Z)-diastereomers. On the other hand, treatment of the dione with acetylmethylene(triphenyl)phosphorane afforded a mixture of (E)-3,3-diphenyl-1-(2-oxo-2-methylethylidene)indan-2-one and unexpected product (E)-3-(3,3-diphenyl-2-oxoindan-1-ylidene)-4-(triphenyl-λ⁵-phosphanylidene)hexane-2,5-dione, whereas with benzoylmethylene(triphenyl)phosphorane gave a mixture of (E)-3,3-diphenyl-1-(2-oxo-2-phenylethylidene)indan-2-one, [(2R ^*,3S ^*)-3-benzoyl-8,8-diphenyl-3,8-dihydro-2H-indeno{2,1-b}furan-2-yl]phenylmethanone and 1,4-diphenyl-2-(3,3-diphenyl-2-hydroxy-3H-inden-1-yl)but-2-ene-1,4-dione. The reaction mechanisms are considered and structural assignments of the new compounds are based on spectroscopic evidence. The molecular structures of the two diastereomers and the unexpected product were elucidated by X-ray crystallography.     

Flip‐type disorder in 3‐substituted 2,2′:5′,2′′‐terthiophenes

In the crystal structures of four thiophene derivatives, (E)‐3′‐[2‐(anthracen‐9‐yl)ethenyl]‐2,2′:5′,2′′‐terthiophene, C₂₈H₁₈S₃, (E)‐3′‐[2‐(1‐pyrenyl)ethenyl]‐2,2′:5′,2′′‐terthiophene, C₃₀H₁₈S₃, (E)‐3′‐[2‐(3,4‐dimethoxyphenyl)ethenyl]‐2,2′:5′,2′′‐terthiophene, C₂₂H₁₈O₂S₃, and (E,E)‐1,4‐bis[2‐(2,2′:5′,2′′‐terthiophen‐3′‐yl)ethenyl]‐2,5‐dimethoxybenzene, C₃₆H₂₆O₂S₆, at least one of the terminal thiophene rings is disordered and the disorder is of the flip type. The terthiophene fragments are far from being coplanar, contrary to terthiophene itself. The central C—C=C—C fragments are almost planar but the bond lengths suggest slight delocalization within this fragment. The crystal packing is determined by van der Waals interactions and some weak, relatively short, C—H...S and C—H...π directional contacts.     

Synthesis of novel spiro[indole-3,3′-pyrrolidin]-2(1H)-ones

Diastereoselective [3+2] cycloaddition of azomethine ylide to 1,3-dimethyl-6-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-3a,9a-diphenyl-3,3a,9,9a-tetrahydroimidazo[4,5-e]thiazolo[3,2-b]-[1,2,4]triazine-2,7(1H,6H)-dione yields hitherto unknown 1,1′,3-trimethyl-3a,9a-diphenyl-3,3a,9,9a-tetrahydrodispiro(imidazo[4,5-e]thiazolo[3,2-b][1,2,4]triazine-6,3′-pyrrolidine-4′,3″-indole)-2,2″,7(1H,1″H)-triones.     

Two androsterone derivatives as inhibitors of androgen biosynthesis

The title compounds, (3R,5S,5′R,8R,9S,10S,13S,14S)‐10,13‐dimethyl‐5′‐(2‐methylpropyl)tetradecahydro‐6′H‐spiro[cyclopenta[a]phenanthrene‐3,2′‐[1,4]oxazinane]‐6′,17(2H)‐dione, C₂₆H₄₁NO₃, (I), and methyl (2R)‐2‐[(3R,5S,8R,9S,10S,13S,14S)‐10,13‐dimethyl‐2′,17‐dioxohexadecahydro‐3′H‐spiro[cyclopenta[a]phenanthrene‐3,5′‐[1,3]oxazolidin‐3′‐yl]]‐4‐methylpentanoate, C₂₈H₄₃NO₅, (II), possess the typical steroid shape (A–D rings), but they differ in their extra E ring. The azalactone E ring in (I) shows a half‐chair conformation, while the carbamate E ring of (II) is planar. The orientation of the E‐ring substituent is clearly established and allows a rationalization of the biological results obtained with such androsterone derivatives.     

The Knoevenagel product of indolin‐2‐one and ferrocene‐1,1′‐dicarbaldehyde

Indolin‐2‐one (oxindole), (I), undergoes a Knoevenagel condensation with ferrocene‐1,1′‐dicarbaldehyde, (II), to afford the title complex 3,3′‐[(E,E)‐ferrocene‐1,1′‐diyldimethylidyne]diindolin‐2‐one dichloromethane disolvate, [Fe(C₂₈H₂₀N₂O₂)]·2CH₂Cl₂, (IV). The structure of (IV) contains two ferrocene complex molecules in the asymmetric unit and displays, as expected, intermolecular hydrogen bonding (N—H...O=C) between the indolin‐2‐one units. Intermolecular π–π stacking interactions are also observed.     

Methylene‐Bridged Metallocenes with 2,2′‐Methylenebis[1H‐inden‐1‐yl] Ligands: Synthesis,Characterization, and Polymerization Catalysis of a Synthetically Simple Class of C2‐ and C2v‐Symmetric ansa‐Metallocenes

The acid‐catalyzed reaction between formaldehyde and 1H‐indene, 3‐alkyl‐ and 3‐aryl‐1H‐indenes, and six‐membered‐ring substituted 1H‐indenes, with the 1H‐indene/CH₂O ratio of 2 : 1, at temperatures above 60° in hydrocarbon solvents, yields 2,2′‐methylenebis[1H‐indenes] 1 – 8 in 50–100% yield. These 2,2′‐methylenebis[1H‐indenes] are easily deprotonated by 2 equiv. of BuLi or MeLi to yield the corresponding dilithium salts, which are efficiently converted into ansa‐metallocenes of Zr and Hf. The unsubstituted dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1H‐inden‐1‐yl]}zirconium ([ZrCl₂( 1′ )]) is the least soluble in organic solvents. Substitution of the 1H‐indenyl moieties by hydrocarbyl substituents increases the hydrocarbon solubility of the complexes, and the presence of a substituent larger than a Me group at the 1,1′ positions of the ligand imparts a high diastereoselectivity to the metallation step, since only the racemic isomers are obtained. Methylene‐bridged ‘ansa‐zirconocenes’ show a noticeable open arrangement of the bis[1H‐inden‐1‐yl] moiety, as measured by the angle between the planes defined by the two π‐ligands (the ‘bite angle’). In particular, of the ‘zirconocenes’ structurally characterized so far, the dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[4,7‐dimethyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl₂( 5′ )] is the most open. The mixture [ZrCl₂( 1′ )]/methylalumoxane (MAO) is inactive in the polymerization of both ethylene and propylene, while the metallocenes with substituted indenyl ligands polymerize propylene to atactic polypropylene of a molecular mass that depends on the size of the alkyl or aryl groups at the 1,1′ positions of the ligand. Ethene is polymerized by rac‐dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1‐methyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl₂( 2′ )])/MAO to polyethylene waxes (average degree of polymerization ca. 100), which are terminated almost exclusively by ethenyl end groups. Polyethylene with a high molecular mass could be obtained by increasing the size of the 1‐alkyl substituent.     

Enantioselective hydrogenation of functionalized olefins catalyzed by Rh-chiral bidentatephosphite complexes

A novel catalytic system for the hydrogenation of dimethyl itaconate has been developed by using rhodium–diphosphite complexes. These chiral diphosphite ligands were derived from glucopyranoside, d-mannitol derivatives, and binaphthyl or H₈-binaphthyl phosphochloridites. The ligands based on the methyl 3,6-anhydro-α-d-glucopyranoside backbone and (R)- and (S)-binaphthol and/or (R)- and (S)-2,2′-dihydroxy-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthol gave almost complete conversion of the dimethyl itaconate and both enantiomers of dimethyl 2-methylsuccinate with excellent enantioselectivities. The stereochemically matched combination of methyl 3,6-anhydro-α-d-glucopyranoside and H₈-(S)-binaphthyl in ligand 2,4-bis{[(S)-1,1′-H₈-binaphthyl-2,2′-diyl]-phosphite} methyl 3,6-anhydro-α-d-glucopyranoside was essential to afford dimethyl 2-methylsuccinate with up to 98% ee. The sense of the enantioselectivity of products was predominantly determined by the configuration of the biaryl moieties of the ligands. An initial screening of [Rh(cod)₂]BF₄ with these ligands in the hydrogenation of (E)-2-(3-butoxy-4-methoxybenzylidene)-3-methylbutanoic acid was carried out. Good enantioselectivity (75% ee) and low yield for (R)-2-(3-butoxy-4-methoxybenzyl)-3-methylbutanoic acid were obtained.     

Synthesis of spiro[2H-indole-2,1′-1H-isoindole]-3,3′-diones,spiro[1H-isobenzofuran-1,2′-2H-indole]-3,3′-diones and spiro[benzofuran-2,1′-isobenzofuran]-3,3′-diones via transannular reactions of eight membered ring intermediates

An auto oxidation-rearrangement product 4 was isolated from a high dilution reaction of ninhydrin with 3,4,5-trimethoxyaniline in water. A general synthesis of this compound and its derivatives 4–6 was devised by oxidation of tetrahydroindeno[1,2-b]indol-10-ones 1–3 with sodium periodate to give isoindolo[2,1-a]-indole-6,11-diones 4–6 in good yield. Compounds 4–6 can be easily transformed into spiro[1H-isobenzofuran-1,2′-2H-indole]-3,3′-diones 8–10 , spiro[2H-indole-2,1′-1H-isoindole]-3,3′-diones 11–13 and isoindole[1,2-a:2′,1′-b]pyrimidine-5,15-diones 15, 16 in high yields. Analogous reactions were performed on 3-amino-5a, 10a-dihydroxybenzo[b]indeno[2,1-d]furan-10-one ( 17 ) to give a dibenzoxocintrione 18 , spiro-[benzofuran-2,1′-isobenzofuran]-3,3′-dione 19 and an isoindol-1-one 20 .     

Preparation of l-serine and l-cystine stereospecifically labeled with deuterium at the β-position

The synthesis of l-serine and l-cystine stereospecifically labeled with deuterium at the β-position is described. The carboxyl group of d-serine was transformed into chirally deuterium-labeled alcohol via asymmetric reduction of 1-deuterio aldehyde, while the original hydroxymethyl group was converted into a carboxyl functionality to afford (2S,3R)-[3-²H]serine. Functional group interconversions of the hydroxyl group in the obtained deuterium-labeled l-serine gave (2R,2′R,3S,3′S)-[3,3′-²H₂]cystine.     

New ylidene and spirocyclopropyl derivatives of cholestanone and dehydroepiandrosterone series and their ability to induce cholesteric mesophase in nematic solvent

New ylidene and spirocyclopropyl derivatives of cholestanone and dehydroepiandrosterone series were synthesized and their structure was determined by X-ray analysis. These compounds may be used as chiral dopants for cholesteric liquid crystal compositions which are applied in bistable displays with low power consumption. The ability of the synthesized substances to induce cholesteric mesophase in 4′-pentyl-1,1′-biphenyl-4-carbоnitrile nematic solvent was examined. The highest values of the helical twisting power |β| (190.0?±?2.3) and (165.5?±?1.9) µm^?1 mol pats^?1 were showed by (E)-2-{[3-(1,1′-biphenyl-4-yl)-1-phenyl-1H-pyrazol-4-yl]methyldene}-cholestanon and (1S,2S)-1-(1-phenyl-3-(4-methoxyphenyl)-1H-pyrazole-4-yl)-2,16′-spirocyclopropyldehydroepiandrosterone, correspondingly.     

Synthese von diastereo- und enantio-selektiv deuterierten β,ε-, β,β-, β,γ- und γ,γ-Carotinen

Synthesis of Diastereo- and Enantioselectively Deuterated β,ε-, β,β-, β,γ- and γ,γ-Carotenes We describe the synthesis of (1′R, 6′S)-[16′, 16′, 16′-²H₃]-β, εcarotene, (1R, 1′R)-[16, 16, 16, 16′, 16′, 16′-²H₆]-β, β-carotene, (1′R, 6′S)-[16′, 16′, 16′-²H₃]-γ, γ-carotene and (1R, 1′R, 6S, 6′S)-[16, 16, 16, 16′, 16′, 16′-²H₆]-γ, γ-carotene by a multistep degradation of (4R, 5S, 10S)-[18, 18, 18-²H₃]-didehydroabietane to optically active deuterated β-, ε- and γ-C₁₁-endgroups and subsequent building up according to schemes \documentclass{article}\pagestyle{empty}\begin{document}${\rm C}_{11} \to {\rm C}_{14}^{C_{\mathop {26}\limits_ \to }} \to {\rm C}_{40} $\end{document} and C₁₁ → C₁₄; C₁₄+C₁₂+C₁₄→C₄₀. NMR.- and chiroptical data allow the identification of the geminal methyl groups in all these compounds. The optical activity of all-(E)-[²H₆]-β,β-carotene, which is solely due to the isotopically different substituent not directly attached to the chiral centres, is demonstrated by a significant CD.-effect at low temperature. Therefore, if an enzymatic cyclization of [17, 17, 17, 17′, 17′, 17′-²H₆]lycopine can be achieved, the steric course of the cyclization step would be derivable from NMR.- and CD.-spectra with very small samples of the isolated cyclic carotenes. A general scheme for the possible course of the cyclization steps is presented.     

Regio‐ and stereospecific assembly of dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidines] from simple precursors using a one‐pot procedure: synthesis,spectroscopic and structural characterization,and a proposed mechanism of formation

The synthesis and characterization of three new dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine] compounds are reported, together with the crystal structures of two of them. (3RS,1′SR,2′SR,7a′SR)‐2′‐(4‐Chlorophenyl)‐1‐hexyl‐2′′‐sulfanylidene‐5′,6′,7′,7a′‐tetrahydro‐2′H‐dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine]‐2,4′′‐dione, C₂₈H₃₀ClN₃O₂S₂, (I), (3RS,1′SR,2′SR,7a′SR)‐2′‐(4‐chlorophenyl)‐1‐benzyl‐5‐methyl‐2′′‐sulfanylidene‐5′,6′,7′,7a′‐tetrahydro‐2′H‐dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine]‐2,4′′‐dione, C₃₀H₂₆ClN₃O₂S₂, (II), and (3RS,1′SR,2′SR,7a′SR)‐2′‐(4‐chlorophenyl)‐5‐fluoro‐2′′‐sulfanylidene‐5′,6′,7′,7a′‐tetrahydro‐2′H‐dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine]‐2,4′′‐dione, C₂₂H₁₇ClFN₃O₂S₂, (III), were each isolated as a single regioisomer using a one‐pot reaction involving l ‐proline, a substituted isatin and (Z)‐5‐(4‐chlorobenzylidene)‐2‐sulfanylidenethiazolidin‐4‐one [5‐(4‐chlorobenzylidene)rhodanine]. The compositions of (I)–(III) were established by elemental analysis, complemented by high‐resolution mass spectrometry in the case of (I); their constitutions, including the definition of the regiochemistry, were established using NMR spectroscopy, and the relative configurations at the four stereogenic centres were established using single‐crystal X‐ray structure analysis. A possible reaction mechanism for the formation of (I)–(III) is proposed, based on the detailed stereochemistry. The molecules of (I) are linked into simple chains by a single N—H…N hydrogen bond, those of (II) are linked into a chain of rings by a combination of N—H…O and C—H…S=C hydrogen bonds, and those of (III) are linked into sheets by a combination of N—H…N and N—H…S=C hydrogen bonds.     

Asymmetric oxidative coupling polymerization affording polynaphthylene with 1,1′-bi-2-naphthol units

The oxidative coupling polymerizations of racemic-, (R)-, and (S)-2,2′-dimethoxymethoxy-1,1′-binaphthalene-3,3′-diols were carried out with a copper catalyst with various ligands, such as N,N,N′,N′-tetramethylethylenediamine (TMEDA), (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine, (−)-sparteine, and (S)-(−)-2,2′-isopropylidenebis(4-phenyl-2-oxazoline) [(−)-Phbox], under an O₂ atmosphere. For example, a 10/1 (v/v) MeOH · H₂O-insoluble polymer with a number-average molecular weight of 3.8 × 10³, from a polymerization with CuCl–TMEDA followed by acetylation of the hydroxyl groups, was obtained in a 71% yield. Polymerization with (−)-Phbox proceeded in an S-selective manner to give a polymer with the highest negative specific rotation from the (S)-monomer. The obtained polymer was successfully converted into a polymer with the optically pure 1,1′-bi-2-naphthol unit based on the original monomer structure, which could be used as a polymeric chiral auxiliary and showed catalytic activity for the asymmetric diethylzinc addition reaction to aldehydes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4528–4534, 2004     

Chromatographische Trennung und Identifizierung diastereomerer Carotinoide mit grossem räumlichem Abstand der chiralen Zentren

Chroma to graphic Separation and Identification of Diastereomeric Carotinoids with Distant Chiral Centers The high-performance liquid chromatographic separation of diastereomeric C₄₀-carotinoids is described possessing chiral centers which are separated by 18 C-atoms (nonaene system). The method is applied to the separation of the two diastereomers of 6,6′-dihydrorhodoxanthin 1a and 1b (ε,ε-carotene-3,3′-dione) and the six diastereomers of tunaxanlhin (ε,ε-carotene-3,3′-diol; 2a–2f ). Conditions for the separation of lutein [(3R, 3′R, 6′R)-β,ε-carotene-3.3′-diol, 3a ], 3′-epi-lutein [(3R,3′S,6′R)-β, ε-carotene-3,3′-diol, 3b ] and its 13′-cis- ( 3c ) and 13-cis-stereo-isomers( 3d ) are also reported. Identification of the different chromatographic fractions was possible by use of authentic synthetic samples or by ¹H-NMR. spectroscopy.     

Intrinsically microporous polyimides containing spirobisindane and phenazine units: Synthesis,characterization and gas permeation properties

A new diamine containing spirobisindane and phenazine units, namely, 3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[cyclopenta[b]phenazine]‐7,7′‐diamine (TTSBIDA) was synthesized starting from commercially available 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane (TTSBI). TTSBI was oxidized to 3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[indene]‐5,5′,6,6′‐tetraone (TTSBIQ) which was subsequently condensed with 4‐nitro‐1,2‐phenylenediamine to obtain 3,3,3′,3′‐tetramethyl‐7,7′‐dinitro‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[cyclopenta[b]phenazine] (TTSBIDN). TTSBIDN was converted into TTSBIDA by reduction of the nitro groups using hydrazine hydrate in the presence of Pd/C as the catalyst. A series of new polyimides of intrinsic microporosity (PIM‐PIs) were synthesized by polycondensation of TTSBIDA with commercially available aromatic dianhydrides. PIM‐PIs exhibited amorphous nature, high thermal stability (T₁₀ > 480 °C) and intrinsic microporosity (BET surface area = 59–289 m²/g). The gas permeation characteristics of films of selected PIM‐PIs were evaluated and they exhibited appreciable gas permeability as well as high selectivity. The CO₂ and O₂ permeability of PIM‐PIs were in the range 185.4–39.2 and 30.6–6.2 Barrer, respectively. Notably, polyimide derived from TTSBIDA and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (PIM‐PI‐6FDA) exhibited high CO₂ and O₂ permeability of 185.4 and 30.6 Barrer with CO₂/CH₄ and O₂/N₂ selectivity of 43.1 and 5.1, respectively. The data of PIM‐PI‐6FDA for CO₂/CH₄ and O₂/N₂ gas pairs were located near Robeson upper bound. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 766–775