bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of 5‐Amino‐9‐benzyl‐6‐formyl‐4‐methoxy‐2‐pivaloylamino‐7,8‐dihydropyrimido[4,5‐b]azepine. A potentially useful intermediate towards the synthesis of pyrimidoazepine based folic acid derivatives
Authors: Miller Michael L. , Ray Partha S.
Published: May 2009

Synthesis of the title compound is described via an intramolecular 1,3‐dipolar cycloaddition reaction between the pyrimidine nitrile oxide 24 and an alkyne dipolarophile tethered to the 6‐position of the pyrimidine ring. The resulting isoxazolopyrimidoazepine cycloadduct 25 was treated with molybdenum hexacarbonyl to provide the titled enamino aldehyde 26.
Conformation and ortho steric effects in a series of 2‐(pyrazol‐1‐yl)quinolines
Authors: Singh Shiv P. , Kumar Dalip , Kumar Devinder , Martínez Ana , Elguero José
Published: May 2009

Nine 2‐(pyrazol‐1‐yl)‐4‐methylquinolines bearing substituents on the pyrazole 3‐ or 5‐positions (H, Me, Et, i‐Pr, t‐Bu) were regioselectively synthesized either using the direct condensation of 2‐chloro‐4‐methylquinoline and sodium salt of 3(5)‐substituted pyrazoles or by treatment of 2‐hydrazino‐4‐methylquinoline with an appropriate β‐ketoaldehyde. The 1H and 13C chemical shifts were discussed taking into account the preferred conformation about the C‐2‐N‐1′ bond as calculated by the AM1 Hamiltonian. It appears that 5‐ethyl and 5‐isopropyl substituted derivatives present short C‐H‐N‐1 interactions. Ortho steric effects appear to be responsible for these conformations.
Syntheses of folic acid models, 6‐(N‐acylarylamino)methyllumazines
Authors: Igarashi Mamoru , Kambe Tohru , Tada Masaru
Published: May 2009

Folic acid models, 1,3‐dimethyl‐6‐(N‐acylarylamino)methyllumazines 9, were synthesized from 6‐bromomethyl‐1,3‐dimethyllumazine (6), which was derived from 5,6‐diamino‐1,3‐dimethyluracil (1) by the condensation with 1,3‐dihydroxyacetone, followed by bromination. The bromide 6 was also prepared by the cycloaddition between 3,6,8‐trioxo‐5,7‐dimethyl‐5,6,7,8‐tetrahydro‐3H‐pyrimido[5,4‐c][1,2,5]oxadiazine (4) and 1‐propenyl trimethylsilyl ether followed by bromination. The folic acid models 9 were also directly synthesized from the oxadiazine 4 and 3‐(N‐acylaryl)amino‐1‐propenyl trimethylsilyl ether 8 by cycloaddition.
Synthesis of 3‐substituted 4,1,2‐benzothiadiazine 4,4‐dioxides and 2 or 3‐substituted 1,4‐benzothiazine 1,1‐dioxides
Authors: Balbi A. , Sottofattori E. , Mazzei M.
Published: May 2009

The title compounds were prepared starting from the synthones 6 using two different synthetic approaches: 3‐substituted 1,4‐benzothiazine 1,1‐dioxides were synthesised by cyclisation with phosphorus oxychloride as the Vilsmeier reagent, while 4,1,2‐benzothiadiazine 4,4‐dioxides and 3‐substituted 1,4‐benzothiazine 1,1‐dioxides were obtained by direct diazotisation or by cyclisation with triethyl orthoformate.
Novel heterocycles derived from substituted aroylthioureas: Synthesis of 3, l‐benzothiazin‐4‐ones, thieno[3,2‐d][1,3]thiazin‐4‐ones and 1,2,4‐thiadiazolo[2,3‐a][3,1]benzothiazin‐5‐ones
Authors: Gütschow M.
Published: May 2009

A series of heterocyclic aroylthioureas has been prepared and investigated as starting materials for ring closure reactions. The formation of several new 3,1‐benzothiazin‐4‐ones and thieno[3,2‐d][1,3]thiazin‐4‐ones (via cyclocondensation reactions) is reported. Oxidative cyclizations were carried out to produce methyl benzothiazole‐4‐carboxylates (via formation of an S‐C bond) as well as 1,2,4‐thiadiazolo‐[2,3‐a][3,1]benzothiazin‐5‐ones (via formation of an SN bond).
Synthesis and structural elucidation of pyrimido‐[1,2‐a]benzimidazoles and fused derivatives. i. dihydropyrimido[1,2‐a]benzimidazoles
Authors: El Ella Dalai Abou , Gößnitzer Edith , Wendelin Winfried
Published: May 2009

The condensation of 2‐benzimidazolarnine (4, BIA) with α,β‐unsaturated ketones 1 affords, according to Desenko, Orlov et al. [12,13], 1,4‐dihydropyrimido[1,2‐a]benzimidazoles (1,4‐DHPBI, 5I). However, the described ring closure reactions could a priori also yield isomeric 1,2‐DHPBI 8I or tautomers of DHPBIs 5I and 8I. An unequivocal proof for the postulated structures 5I was not presented. We prepared, as described [12,13], BIA‐chalcone‐ and BIA‐benzalacetone‐condensate X and Y, 5a, e or 8a, e, and additionally, their hydrochlorides. One and two dimensional high resolution nmr analyses showed that only isomers 5a, e and salts 5a, e·HCl were generated. In DMSO‐d6 these isomers exclusively exist as 1,4‐dihydro tautomers 5a, eI and 5a,eI·HCl. In trifluoroacetic acid 3,4‐dihydro tautomers 5a, eIII·CF3COOH besides of tautomers 5a, eI·CF3COOH (≈︁1:4) were ascertained. Action of ethanolic hydrochloric acid on base 5eI afforded, besides of 5eI·HCl as main product, a small amount of 2‐methyl‐4‐phenyltetrahydropyrim‐ido[1,2‐a]benzimidazol‐2‐ol hydrochloride 9e·HCl. The reaction of BIA 4 with α,β‐unsaturated ketones 1b‐d and f yielded 1,4‐DHPBI 5b‐dI and 5fI and their hydrochlorides, respectively. The stereochemistry of bases 5a, eI, of salts 5a‐eI·HCl and 5a, eIII·CF3COOH, and of addition product 9e·HCl was elucidated by nmr (stereoformulae in Figures 1–3 and Scheme 5). The accomplished nmr‐analyses are documented in detail and discussed.
Syntheses of various 5‐(3′‐substituted phenyl)uracils
Authors: Wellmar Ulf , Hömfeldt Anna‐Britta , Gronowitz Salo
Published: May 2009

The Suzuki Pd(0)‐catalysed coupling between arylboronic acids and aryl bromides or iodides in weakly alkaline medium has been used for the preparation of 5‐(3′‐chlorophenyl)‐, 5‐(3′‐iodophenyl)‐, 5‐(3′‐aminophenyl)‐, 5‐(3′‐azidophenyl)‐, 5‐(3′‐methylthiophenyl)‐ and 5‐(3′‐styryl)‐substituted 2,4‐di‐t‐butoxypyrimidines. In the coupling between 2,4 di‐t‐butoxy‐5‐pyrimidineboronic acid and the six different aryl halides that were used as coupling partners, only 1‐azido‐3‐bromobenzene did not give satisfactory yields, 18%. The other five aryl halides gave the desired 5‐(3′‐substituted phenyl)‐2,4‐di‐r‐butoxypyrimidines in 41–92% yield. Dealkylation of these five 5‐(3′‐substituted phenyl)‐2,4‐di‐t‐butoxypyrimidines in 2.5M hydrochloric acid gave the corresponding 5‐(bromoaryl)uracils in almost quantitative yields. 5‐(3′‐Azidophenyl)uracil was prepared in 43% yield directly from 5‐(3′‐aminophenyl)‐2,4‐di‐r‐butoxypyrimidine.
1H‐NMR study on the tautomer ratios between the hydrazone imine and diazenylenamine forms in 3‐(arylhydrazono)‐methyl‐2‐oxo‐1,2‐dihydroquinoxalines
Authors: Kurasawa Yoshihisa , Takano Akiko , Kato Kyoko , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa
Published: May 2009

The o‐substituted 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines 1a‐c and 2a, c were synthesized to investigate the tautomeric behavior between the hydrazone imine A and diazenylenamine B forms in a series of mixed dimethyl sulfoxide/trifluoroacetic acid media. The chemical shifts of the hydrazone NH, N4‐H, hydrazone CH, and diazenyl CH protons for o‐, m‐, and p‐substituted 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines 1 and 2 synthesized so far are summarized in Tables 3 and 4, respectively, which are found to be useful for the specification of the proton signals due to the hydrazone imine form A (hydrazone NH, hydrazone CH) and diazenylenamine form B (N4‐H, diazenyl CH).
A facile synthesis of new β‐lactams
Authors: Lancelot J. C. , Saturnino C. , El‐Kashef H. , Perrine D. , Mahatsekake C. , Prunier H. , Robba M.
Published: May 2009

Several new β‐lactams have been synthesized in good yields, via the cyclization of 3‐chloro‐N‐arylpropionamides in a mixture of N, N‐dimethylformamide and anhydrous sodium carbonate under a nitrogen atmosphere.
Synthesis of some pyrimido[4′,5′:4,5]thieno[2,3‐b]quinolines and related heterocycles
Authors: Hafez A. A. Abdel , El‐Dean A. Kamal , Hassan A. A. , El‐Kashef H. S. , Rault S. , Robba M.
Published: May 2009

Several thieno[2,3‐b]quinolines 6a‐i have been synthesized. These compounds were used as key intermediates in the synthesis of oxazino[4′,5′:4,5]thieno[2,3‐b]quinoline 8, pyrimido[4′,5′:4,5]‐thieno[2,3‐b]quinolines 9–12, triazino[4′,5′:4,5]thieno[2,3‐b] quinolines 14 and imidazo[4′,5′:4,5]‐thieno[2,3‐b]quinolines 17.
O‐Alkylation of 3‐hydroxy‐1‐phenyl‐2‐pyrazolin‐5‐one
Authors: Molinari Aurora , Oliva Alfonso
Published: May 2009

3‐Hydroxy‐1‐phenyl‐2‐pyrazolin‐5‐one 1 reacts with primary, secondary and allylic alcohols under catalytic acidic conditions and in the presence of 3 Å molecular sieves, to afford 3‐alkoxy‐1‐phenyl‐2‐pyrazolin‐5‐ones 3.
Azo dyes derived from Aminophenylbenzacridinones. VIII
Authors: Martínez Roberto , Arteaga Paulino , Mancera Claudia
Published: May 2009

The preparation of novel azo‐dyes from p‐aminophenylbenzacridinones is described. The structure of all the products was corroborated by ir, mass spectrometry and 1H‐nmr.
Spectroscopic studies of delavirdine mesylate (U‐90,152T) a bis(heteroaryl)piperazine (BHAP) HIV reverse transcriptase inhibitor
Authors: Farley Kathleen A. , Walker Gregory S. , Robins Russell H. , Kupstas‐Guido Jane E. , Duholke Wayne K. , Romero Donna L. , Morge Raymond A. , Meulman Paul A. , Chao Robert S. , Havens Jeffrey L. , Gage James R. , Lyster Mark A. , Fagerness Paul E. , Martin Gary E.
Published: May 2009

Complete spectral assignments, including mass spectral fragmentation pathways, 1H and 13C resonances, and major infrared absorbance bands for the BHAP (bis(heteroaryl)piperazine) HIV reverse transcriptase inhibitor delavirdine are reported.
Haloacetylated enol ethers. 14 [6]. Reaction of β‐alkoxyvinyl trifluoromethyl ketones with N‐methylhydroxylamine
Authors: Martins Marcos A. P. , Flores Alex F. C. , Bastos Giovani P. , Zanatta Nilo , Bonacorso Helio G.
Published: May 2009

The reaction of a series of β‐methoxyvinyl trifluoromethyl ketones [CF3COC(R2)C(OMe)R1, where R1 = Me, ‐(CH2)3‐C3, ‐CH2)4‐C3, Ph and R2 = H, Me, ‐(CH2)3‐C4, ‐(CH2)4‐C4] with N‐methylhydroxylamine is reported. The regiochemistry of the reaction are explained by MO calculation data.
Synthesis of pyrido[3,2‐e]pyrrolo[2,1‐c][1,2,4]triazines from pyrido[3,2‐e][1,2,4]triazine derivatives
Authors: Savelli Francesco , Boido Alessandro , Ciarallo Giovanni
Published: May 2009

In carrying on our interest in heteropolycyclic structures with biological activities, we projected the preparation of compounds containing the pyrido[3,2‐e][1,2,4]triazine or pyrido[2,3‐b][1,4]triazepine systems. The established synthetic approach for the preparation of latter system led to the triazine derivatives 5a‐f while a new bicyclic triazepine structure 6 is accomplished with difficulty.

In expanding the pyridotriazine structure, we obtained derivatives of a new tricyclic structure, 5‐substituted‐6a‐ethyloxycarbonyl‐5,6,6a,7‐tetrahydropyrido[2,3‐e]pyrrolo[2,1‐c][1,2,4]triazin‐9(8H)‐ones 8 in which the triazine ring is fused with a pyrrole nucleus.

Compounds 5a‐f and 8a,b will be tested as potential CNS depressant, antiinflammatory, analgesic and antibacterial agents.
1,3,5‐tripyridylbenzenes via threefold stille couplings
Authors: Fan Yun‐Hua , Haseltine John
Published: May 2009

Novel 1,3,5‐tripyridylbenzenes are synthesized using a threefold Stille coupling as the strategic reaction.
Investigation of the reaction of N‐substituted indolylborates: Palladium catalyzed cross‐coupling reactions and intramolecular alkyl migration reactions
Authors: Ishikura Minoru , Agata Isao , Katagiri Nobuya
Published: May 2009

The palladium catalyzed cross‐coupling reaction of indolylborates with various N‐protecting groups was investigated, where N‐Methyl, N‐methoxy, and N‐tert‐butoxycarbonyl groups were found to be useful. However, triethyl(1‐methoxymethylindol‐2‐yl)borate could not be used for this reaction. It was also found that the alkyl migration reaction of trialkyl(1‐methoxymethylindol‐2‐yl)borate produced 2‐alkyl‐1‐methyl‐indole accompanied by the unexpected reduction of 1‐methoxymethyl group to 1‐methyl group.
Synthesis, crystal structure and spectroscopic studies of 3‐hydrazono‐ and 3‐hydroxyiminoquinolin‐2‐ones
Authors: Mitsos Christos , Petrou John , Igglessi‐Markopoulou Olga , Markopoulos John
Published: May 2009

3‐(Hydrazonoethyl)quinolinones 6–11, 13 and 3‐(hydroxyiminoethyl)quinolinones 14, 15 are prepared by a condensation reaction of 3‐acetylquinolinones 4, 5 with a variety of 1,2‐(bis)nucleophiles. The structures of the isolated compounds have been elucidated using 1H and 13C nmr spectroscopy. X‐ray diffraction studies of compound 14 were also performed.
Direct functionalization of 4,5‐dichloropyridazin‐6‐one
Authors: Chung Hyun‐A , Kweon Deok‐Heon , Kang Young‐Jin , Park Jung‐Won , Yoon Yong‐Jin
Published: May 2009

Direct functionalization of 4,5‐dichloropyridazin‐6‐one with some nucleophiles in seven solvents gave regioselectively 5‐halo‐4‐substituted‐pyridazin‐6‐ones as main product. Reaction of 4,5‐dichloropyridazin‐6‐one with 2‐mercaptopyrimidine (2 equivalents) also afforded 4,5‐di(pyrimidin‐2‐ylsulfanyl)pyridazin‐6‐one as the main product.
Polycyclic fused phenanthridines: An alternative approach from benzotriazoles
Authors: Katritzky Alan R. , Du Weihong , Matsukawa Yasuhisa , Ghiviriga Ion , Denisenko Sergey N.
Published: May 2009

We describe an alternative approach to polycyclic phenanthridines (7) and some of their analogues using conditions much milder than those previously reported. The procedure includes the generation of a benzotriazole stabilized carbanion, oxidation of the resulting anion to a radical, and elimination of nitrogen followed by ring closure to produce phenanthridines.
Synthesis of 2‐aryl‐2,3‐dihydro‐4‐styrylpyrimidodiazepines in the reaction of 4,5,6‐triaminopyrimidine and 2,4,5,6‐tetraaminopyrimidine with diarylidenacetones
Authors: Insuasty Braulio , Insuasty Henry , Quiroga Jairo , Nogueras Manuel , Sánchez Adolfo , López M. Dolores
Published: May 2009

New 6‐amino and 6,8‐diamino‐2‐aryl‐2,3‐dihydro‐4‐styryl‐1H‐pyrimido[4,5‐b][1,4]diazepines were obtained in the reaction of 2,4,5,6‐tetraaminopyrimidine 1a and 4,5,6‐triaminopyrimidine 1b with one equivalent of the diaryli dene acetones 2 in absolute ethanol with acetic acid as the catalyst. Structure analysis of 6‐amino and 6,8‐diamino‐2‐aryl‐2,3‐dihydro‐4‐styryl‐1H‐pyrimido[4,5‐b][1,4]diazepines 3a‐i, determined by detailed nmr measurements, reveals a high regioselectivity of this reaction.
New indolium and quinolinium dyes sensitive to aqueous halide ions at physiological concentrations
Authors: Geddes Chris. D. , Douglas Peter , Moore Christopher P. , Wear Trevor J. , Egerton Peter L.
Published: May 2009

Twelve new highly fluorescent dyes have been produced by the reaction of two heterocyclic nitrogen bases with 8‐bromooctanoic acid, 11‐bromoundecanoic acid and 15‐bromopentadecanoic acid. The bromide counter ions of the first six dyes have been replaced with the tetraphenylborate ion. Unlike the bases themselves, the quaternary salts are water soluble and have fluorescence characteristics independent of pH in the pH range 7–11. Both the fluorescence intensity and fluorescence lifetime of dyes 1–12 are reduced in the presence of aqueous halide ions allowing halide concentrations to be determined accurately at physiological levels. All the dyes have been characterised in terms of steady state fluorescence spectra and steady‐state Stern‐Volmer analysis.
Cycloadditions of adamantanethione S‐methylide to CC multiple bonds
Authors: Mloston Grzegorz , Huisgen Rolf , Huber Helmut , Stephenson David S.
Published: May 2009

Adamantanethione S‐methylide (12) is a nucleophilic 1,3‐dipole which easily combines with electrophilic acetylenic and ethylenic bonds affording dihydrothiophene and thiolane derivatives, usually in high yields. The S‐methylide 12, generated by extrusion of nitrogen from the 2,5‐dihydro‐1,3,4‐thiadiazole 11, can not be isolated, but is intercepted in situ by dipolarophiles; otherwise, 12 furnishes irreversibly the spirothiirane 13. The 1H nmr spectra and mass spectra establish the regiochemistry for the adducts of methyl propiolate, acrylonitrile, methyl acrylate, benzylidenemalononitrile and methyl α‐cyanocinnamate. The 1,3‐dipole does not react with common alkenes; the highly strained trans‐cyclooctene gives rise to a cycloadduct.
An unexpected result in the condensation of 2‐amino‐6‐bromopyridine with ethyl 4‐chloroacetoacetate: Four dihalo‐substituted pyrido[1,2‐a]pyrimidin‐4‐ones as reaction products
Authors: Ferrarini Pier Luigi , Mori Claudio , Mori Filippo , Saccomanni Giuseppe , Barontini Silvia , Macchia Marco , Barili Pier Luigi , Hamdan Mahmoud
Published: May 2009

We report here the condensation of 2‐amino‐6‐bromopyridine with ethyl 4‐chloroacetoacetate in polyphosphoric acid. In this reaction, a mixture of the four possible dihalo‐4H‐pyrido[1,2‐a]pyrimidin‐4‐ones 1–4 was obtained.
X‐ray crystallographic and NMR structural studies of trans‐2,3‐dichloro‐5‐ethyl‐2,3‐dihydrothieno[2 3‐b]pyridine syn‐1‐oxide reactions of thiophene rings with hypochlorite reagents
Authors: Klemm Leroy H. , Weakley Timothy J. R. , Yoon Myungok
Published: May 2009

X‐ray analysis of a crystalline product obtained by treatment of 5‐ethylthieno[2,3‐b]pyridine with excess acidified hypochlorite establishes its stereochemistry as trans‐2,3‐dichloro‐5‐ethyl‐2,3‐dihydrothieno‐[2,3‐b]pyridine syn‐1‐oxide (5), wherein the pyridine ring is planar and the dihydrothiophene ring is non‐planar with a C2‐S‐C7a angle of 86.6°. The trans geometry is corroborated by a proton‐proton coupling constant J2,3 of 6.8 Hz. Comparison of 1H and 13C nmr data for 5 with analogous crystalline 2,3‐dichloro‐1‐oxide addenda isolated in the isosteric benzo[b]thiophene and thieno[2,3‐b]pyridine parent systems indicates that some proposed stereochemical assignments are questionable.
A convenient method for the synthesis of six‐membered heterocyclic enaminones
Authors: Puebla Pilar , Honores Zoila , Medarde Manuel , Caballero Esther , Feliciano Arturo San , Morán Lourdes
Published: May 2009

Enaminones are widely employed in the synthesis of heterocycles, however heterocyclic enaminones and their use in the synthesis of more complex systems have been less studied. The reaction between 4‐chloroacetylacetate and aliphatic or aromatic 1,2‐aminoalcohols, 1,2‐aminothiols or 1,2‐diamines, yields in one pot a six‐membered 1,4‐heterocyclic system containing the enaminone moiety.
A new efficient route to 3‐vinylthiophene
Authors: Nicolas Maël , Fabre Bruno , Pilard Jean‐François , Simonet Jacques
Published: May 2009

The synthesis of 3‐vinylthiophene was efficiently achieved in two steps. 3‐(2‐bromoethyl)thiophene prepared from 3‐(2‐ethanol)thiophene was converted to the title compound (70% overall yield) using tetraglyme as a solvent and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as a base.
Characterization of a trace by‐product of the synthesis of the protease inhibitor tipranavir (PNU‐140690)
Authors: Martin Gary E. , Robins Russell H. , Crow Frank W. , Duholke Wayne K. , Guido Jane E. , Hadden Chad E. , Kaluzny Brian D. , Thamann Thomas J. , Pearlman Bruce A.
Published: May 2009

TipranavirTM (PNU‐140690) is a protease inhibitor under clinical investigation for the treatment of human acquired immunodeficiency syndrome (AIDS). During scale‐up synthesis of clinical quantities of the bulk drug, a colored, transient by‐product of the final coupling reaction was observed. Quantities of this colored, transient chemical species were too low (<<0.1%) for characterization by conventional spectroscopic methods. It was, however, possible to isolate sufficient material for characterization based on mass spectrometry and submicro inverse‐detection gradient (SMIDG) nmr methods by methanol stripping of silica gel that had been used in purification of bulk drug. This process afforded an enriched feedstock from which small quantities of this highly colored and unstable (halflife < 18 hours in methanol and < 10 minutes in acetone) trace contaminant could be isolated by semi preparative reversed phase hplc. The impurity was identified as an unstable Zincke salt formed by the condensation of two molecules of the anilino precursor and the pyridine used as a base in the final step of the synthetic process. Following identification of this impurity, efforts were undertaken to engineer it out of the synthetic process.
Intermediates for the synthesis of indole alkaloids. Synthesis of tetrahydrocarbazole derivatives
Authors: Ergün Y. , Bayraktar N. , Patir S. , Okay G.
Published: May 2009

The synthesis of new precursors 8 and 15 for the synthesis of tetracyclic indole alkaloids were described. Many new intermediates 4‐7 and 9‐14 have also been synthesized.
Synthesis and nuclear magnetic resonance spectroscopic studies of 1‐arylpyrroles
Authors: Lee Chang Kiu , Jun Jung Ho , Yu Ji Sook
Published: May 2009

A series of m‐ and p‐substituted 1‐phenyl, 1‐benzyl, 1‐benzoyl, and 1‐(2‐phenylethyl)pyrroles was prepared and their 1H and 13C nmr spectroscopic characteristics were examined. In general, good correlations were observed between the chemical shift values of the βH and the βC of pyrroles [except 1‐(2‐phenylethyl)pyrroles] and the Hammettt σ. The observation may be explained in terms of the electronic effects of the substituents which are transmitted through bonds and through space by interaction of the p orbitals between βCs of the pyrrole ring and m‐ and pCs of the phenyl ring. Substituent constants of 1‐pyrrolyl, 1‐pyrrolylmethyl, and 1‐pyrroloyl groups for the 1H and 13C chemical shifts of phenyl ring are also presented.
Synthesis of thiophene/phenylene co‐oligomers. I. Phenyl‐capped oligothiophenes
Authors: Hotta S. , Lee S. A. , Tamaki T.
Published: May 2009

We report the synthesis of phenyl‐capped oligothiophenes via improved synthetic schemes. These schemes are based on the Grignard coupling reaction and enable us to obtain the target compounds at high yields. The resulting materials have been fully characterized through nmr and ir spectroscopies. The ir analysis is particularly useful in characterizing the materials of higher molecular weight, since those materials are difficult to dissolve in organic solvent. We also show an improvement on preparation of halogenated (oligo)thiophenes that are used as intermediates for synthesizing the target compounds. An alternative synthetic route to the phenyl‐capped oligothiophenes that utilizes the Suzuki coupling reaction is presented as well.
Synthetic approaches to 3‐substituted‐5′‐(N‐pyridiniummethyl)‐4′,5′‐dihydropsoralen
Authors: Jabin Ivan , Heindel Ned D. , Rapp Robert D. , Laskin Jeffrey D.
Published: May 2009

New synthetic approaches to 3‐substituted‐5′‐(N‐pyridiniummethyl)‐4′,5′‐dihydropsoralens are described. The novel pathways presented utilize appropriately substituted coumarins and 4′,5′‐dihydropsoralens. The compounds proposed represent potential therapeutic agents for psoralen uv radiation treatment.
Synthesis and conversion of 2‐(pyrazol‐1‐yl)quinoxaline 4‐oxides
Authors: Kim Ho Sik , Kwag Sam Tag , Choi Kyung Ok , Okamoto Yoshihisa , Kajiwara Shinnosuke , Fujiwara Noriko , Kurasawa Yoshihisa
Published: May 2009

The reaction of 6‐chloro‐2‐hydrazinoquinoxaline 4‐oxide 1b with acetylacetone or benzoylacetone gave 6‐chloro‐2‐(3,5‐dimethylpyrazol‐i‐yl)quinoxaline 4‐oxide 5a or 6‐chloro‐2‐(3‐methyl‐5‐phenylpyrazol‐1‐yl)quinoxaline 4‐oxide 5b, respXectively. Compound 5a or 5b was converted into the pyrrolo[1,5‐a]quinoxaline 6a or 6b, triazolo[4,3‐a]quinoxaline 9a or 9b, and tetrazolo[1,5‐a]quinoxaline 10.
Perhydro‐1,3‐diazepine‐2,4‐diones by cyclization of 4‐ureidobutyric acids with thionyl chloride: A reinvestigation
Authors: Heckendorn Roland , Winkler Tammo
Published: May 2009

The structures of the previously reported aryl‐perhydro‐1,3‐diazepine‐2,4‐diones are shown to be pyrro‐lidinone carboxamide derivatives by nmr spectroscopy.
Nucleophilic substitution studies on nitroimidazoles, and applications to the synthesis of biologically active compounds
Authors: Chauvière Gérard , Viodé Cécile , Périé Jacques
Published: May 2009

The rationalization of the synthesis of substituted analogs of megazol, a biologically active 5‐nitroimidazole at position 4 of the imidazole ring, had led to the study of intermediate steps. The methylation by diazomethane of 2,4‐(5)dihalogeno‐5‐(4)nitroimidazole is regioselective leading to 2,4‐dihalogeno‐1‐methyl‐5‐nitroimidazole 2. On this compound 2, hard nucleophiles such as cyanide, methoxide or hydride anions react only with the halogen at the 2 position; whereas soft nucleophiles such as amine, thiol or trifluoromethyl anion from an organocopper species react only with the halogen at postion 4 in the intermediate 3b or compound 4b.
A new synthetic entry to 3‐carboxamido‐4‐carboxylic acid derivatives of isoxazole and pyrazole
Authors: Vicentini Chiara B. , Mazzanti Manuela , Morelli Carlo F. , Manfrini Maurizio
Published: May 2009

Ethyl 2‐amino‐3‐methoxycarbonyl‐4‐oxo‐2‐pentenoate (3) reacts with hydroxylamine or hydrazines to give isoxazole and pyrazole ortho‐dicarboxylic acid esters 4 and 5, respectively. Partial hydrolysis of diesters 4 and 5 afforded the corresponding dicarboxylic acid monoesters 6 and 7. Amidation of the intermediate acid chlorides 8,9 followed by hydrolysis of 4‐methylesters 10, 11 gave the title compounds 1 and 2, respectively.
Since 1995 the new chemistry of multicomponent reactions and their libraries, including their heterocyclic chemistry
Authors: Ugi Ivar , Domling Alexander , Werner Birgit
Published: May 2009

A growing number of products, including many heterocycles, can be prepared by the one‐pot MultiComponent Reactions (MCRs) just by mixing three or more educts, and in many cases practically quantitative yields of pure products can be obtained. The 3CR by α‐aminoalkylations of nucleophiles began in the middle of the last century, and the syntheses of heterocycles by MCRs of three and four components were introduced by Hantzsch in the 1880s. The MCRs of the isocyanides with four and more educts began in 1959, and their compound libraries were mentioned since 1961. However, only since 1995 the often automated one‐pot chemistry of the MCR of the isocyanides is used extensively. If a chemical compound can be prepared by a sequence of two component reactions or a suitable MCR, the latter is always a superior procedure. The U‐4CR can be combined with other chemical reactions and MCRs as one‐pot reactions of n > 4 components, and such unions even have a much greater variety of structurally and stereochemically different products. The educts and products of Ugi‐type MCRs are more variable than those of all previous chemical reactions and other MCRs. Due to the progress in screening and automation processes in the last few years, many new compounds have been formed and investigated more rapidly than ever before. The search for new desirable products can be accomplished more than 10,000 times faster than by the older conventional methods. The now popular chemistry of the MCRs of the isocyanides fills the since long empty part of organic chemistry.
Study of the reactivity of α‐acylenaminoketones. Synthesis of pyrazoles
Authors: Negri Giuseppina , Kascheres Concetta
Published: May 2009

The reactions of 4‐(methylamino)‐3‐penten‐2‐one with diazoketones yielded the α‐acylenaminoketones 1–3 in good yields. Preparation of the α‐acylenaminoketone 4 was carried out by treatment of 4‐(t‐butyl‐amino)‐3‐penten‐2‐one with benzoyl chloride being followed by reaction of transamination with methyl‐amine. The reactions were carried out in five different solvents and were submitted to gas chromatogra‐phy/mass spectrometry analysis, with the goal of obtaining substituted pyrazoles and determining which of the carbonyls would preferentially be attacked by the nucleophile. The reactions of compounds 1–4 with hydrazine reagents led to the formation of the pyrazoles 5–7a‐q. Small amounts of 4‐methylamino‐2‐pentenones 10a‐q, amides 11a‐q and pyrazoles 12a‐q were also obtained in these reactions. The unexpected formation of pyrazoles 15d,h,q was detected when methanol and N,N‐dimethylformamide were used as solvents in the reactions of α‐acylenaminoketone 4 with hydrazine reagents.
Solvent‐ and concentration‐sensitive fluorescence of 2‐(3,4,5,6‐tetrafluoro‐2‐hydroxyphenyl)benzoxazole
Authors: Tanaka Kiyoshi , Deguchi Makoto , Yamaguchi Satoru , Yamada Kouji , Iwata Satoru
Published: May 2009

2‐(3,4,5,6‐Tetrafluoro‐2‐hydroxyphenyl)benzoxazole (2) emits the long wavelength fluorescence around 500 nm in nonpolar solvent via the intramolecular proton transfer process in the excited state of 2 (enol‐form) and also emits the intermediate wavelength fluorescence around 440 nm in polar solvent, which is assumed to originate from the excited state of 2 (anion). The ease of formation of 2 (anion), compared to 2‐(2‐hydroxyphenyl)benzoxazole (1), is explained by the strongly inductive fluorine atoms. In a solvent with the intermediate polarity, 2 emits both fluorescences and their relative intensity is dependent on the concentration of 2, which is supposed to be caused by the high sensitivity of the intermediate wavelength emission to the concentration quenching.
Free radical 4‐nitrophenylation of thieno[2,3‐b]pyridine. Part 2: Isolation and structural studies of three samples of mono (4‐nitrophenyl) products; relative yields of the five possible isomers
Authors: Klemm Leroy H. , Weakley Timothy J. R. , Gilbertson Robert D.
Published: May 2009

From the crude mixtures of isomeric 4‐nitrophenylthieno[2,3‐b]pyridines (3) previously reported [1] were isolated three analytically pure samples, viz. the 2‐isomer (yellow needles, mp 258°, 3a), the 6‐isomer (red prisms, mp 182°, 3e), and a ternary mixture of the 2‐, 3‐, and 4‐isomers (orange needles, mp 213°, 3a:3b:3c = 1.3:1.0:0.5). The 258° compound was identified as either 3a or 3b by its 1H nmr spectrum and definitively as the former by its x‐ray crystallographic analysis. The isomeric identities of the 182° and 213° samples were established from their 1H nmr spectra only. No 5‐isomer (3d) was identified. Semi‐quantitatively, relative isomeric yields fit the pattern 2‐ (64%)>>6‐ (14%)≥3‐ (12%)>4‐ (6%)≥5‐(≤4%). Crystallographic data for 3a are presented.
Armed‐azacrown ethers having dual binding sites in a side arm: Complexing abilities and crystal structure of two alkali‐metal complexes
Authors: Habata Yoichi , Saeki Tomomi , Akabori Sadatoshi , Zhang Xian X. , Bradshaw Jerald S.
Published: May 2009

New armed‐monoaza‐12‐crown‐4 and armed‐monoaza‐15‐crown‐5 ethers having dual phenolic OH and pyridine nitrogen binding sites in a side arm were prepared by the Mannich reaction of N‐methoxymethyl‐monoazacrown ethers with 3‐hydroxypyridine. Complexation studies of these new hydroxypyridine‐armed ligands were carried out by liquid membrane transport, 1H nmr titration experiments, thermodynamic values (log K, ΔH and TΔS), and X‐ray crystallography of two alkali‐metal complexes. These results indicate that the oxygen atom of the phenolic OH group and pyridine nitrogen atom of the side arm are involved in complexation under basic and neutral conditions, respectively.
Intermuscular adipose tissue (IMAT): Association with other adipose tissue compartments and insulin sensitivity
Authors: Boettcher Michael , Machann Jürgen , Stefan Norbert , Thamer Claus , Häring Hans‐Ulrich , Claussen Claus D. , Fritsche Andreas , Schick Fritz
Published: May 2009

Purpose

To quantify intermuscular adipose tissue (IMAT) of the lower leg as well as to investigate associations with other adipose tissue (AT) compartments. The relationship between IMAT and insulin sensitivity was also examined.

Materials and Methods

Standardized quantification of IMAT was performed in a large cohort (N = 249) at increased risk for type 2 diabetes in the right calf by T1‐weighted fast spin‐echo imaging at 1.5T (Magnetom Sonata; Siemens Healthcare). Additionally, whole‐body AT distribution was assessed. Insulin sensitivity was determined by glucose clamp.

Results

Males showed significantly more IMAT than females (2.1 ± 1.1 cm2 vs. 1.5 ± 0.9 cm2; P < 0.001). IMAT correlated well with other AT depots, especially with visceral AT (VAT; rfemales = 0.52, P < 0.0001 vs. rmales = 0.42, P < 0.0001). Moreover, IMAT showed a negative correlation with the glucose infusion rate (GIR; rfemales = −0.43, P = 0.0002 vs. rmales = −0.40, P = 0.0007).

Conclusion

Quantification of IMAT is possible by standard MR techniques. AT distribution of the lower leg is comparable to the visceral compartment with males having higher IMAT/VAT but lower subcutaneous AT (SCAT). IMAT seems to be involved in the pathogenesis of insulin resistance, as shown by the significant negative correlation with GIR. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.
Change in serum COMP concentration due to ambulatory load is not related to knee OA Status
Authors: Mündermann Annegret , King Karen B. , Smith R. Lane , Andriacchi Thomas P.
Published: May 2009

The aim of this study was to test the hypothesis that a change in serum cartilage oligomeric matrix protein (COMP) concentration is related to joint load during a 30‐min walking exercise in patients with medial compartment knee osteoarthritis (OA) and in age‐matched control subjects. Blood samples were drawn from 42 patients with medial compartment knee OA and from 41 healthy age‐matched control subjects immediately before, immediately after, and 0.5, 1.5, 3.5, and 5.5 h after a 30‐min walking exercise on a level outdoor walking track at self‐selected normal speed. Serum COMP concentrations were determined using a commercial ELISA. Basic time–distance gait variables were recorded using an activity monitor. Joint loads were measured using gait analysis. Serum COMP concentrations increased immediately after the walking exercise (+6.3% and +5.6%; p < 0.001) and decreased over 5.5 h after the exercise (−11.1% and −14.6%; p < 0.040 and p = 0.001) in patients and control subjects, respectively. The magnitude of increase in COMP concentration did not differ between groups (p = 0.902) and did not correlate with any variables describing ambulatory loads at the joints of the lower extremity. These results, taken together with a previous study of a younger healthy population, suggest the possibility that the influence of ambulatory loads on cartilage turnover is dependent on age. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1408–1413, 2009
Diagnostic accuracy of neutrophil‐derived circulating free DNA (cf‐DNA/NETs) for septic arthritis
Authors: Lögters Tim , Paunel‐Görgülü Adnana , Zilkens Christoph , Altrichter Jens , Scholz Martin , Thelen Simon , Krauspe Rüdiger , Margraf Stefan , Jeri Teresa , Windolf Joachim , Jäger Marcus
Published: May 2009

The release of “neutrophil extracellular traps” (NETs) has been identified as a novel immune response in innate immunity. NETs are composed of neutrophil‐derived circulating free DNA (cf‐DNA) and neutrophil cytoplasm‐derived proteins such as proteases. In this study, we analyzed the putative diagnostic value of synovial cf‐DNA/NETs for identification of septic arthritis. Forty‐two patients with a joint effusion who had undergone arthrocentesis were included. From synovial fluid, cf‐DNA/NETs (j‐cf‐DNA) levels were directly quantified. Diagnostic value of j‐cf‐DNA was compared with white blood cells (WBC), synovial white blood cells (j‐WBC), C‐reactive protein (CRP), j‐IL‐6, j‐TNF alpha, j‐IL‐1 beta, and myeloperoxidase (j‐MPO). Sensitivity, specificity, positive and negative predictive value, as well as ROC‐curves for each parameter were calculated. Synovial fluid cf‐DNA/NETs values from patients with septic arthritis (3,286 ± 386 ng/ml, n = 9) were significantly increased compared to patients with noninfectious joint inflammation (1,040 ± 208 ng/ml, n = 17) or osteoarthritis (278 ± 34 ng/ml, n = 16, p < 0.01). In conjunction with j‐cf‐DNA, j‐IL‐6 and j‐IL‐1 beta were significantly elevated (p < 0.01), but WBC, CRP, and j‐WBC were not. At a cut‐off of 300 ng/ml, j‐cf‐DNA had a sensitivity of 0.89, a specificity of 1.0, a positive predictive value of 1.0, and a negative predictive value of 0.97. Receiver operation curves revealed largest areas under the curve for cf‐DNA/NETs (0.933) and j‐IL‐6 (0.951). cf‐DNA/NETs seem to be a valuable additional marker for the diagnosis of septic arthritis or periprosthetic infections. However, this result should be confirmed in a large clinical trial. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1401–1407, 2009
Near‐IR surface‐enhanced Raman spectrum of lignin
Authors: Agarwal Umesh P. , Reiner Richard S.
Published: May 2009

Compacted powders of commercially available nano‐ and microparticles of silver were used to successfully induce the surface‐enhanced Raman scattering (SERS) effect in spruce milled‐wood lignin (MWL). For the two silver particle sizes used in this investigation, the spectra were mostly similar. Some general characteristics of the lignin SERS spectrum are described. The SERS technique was found to be sensitive for detecting lignin. Significant spectral changes were present between the SERS and normal Raman spectra of MWL. The SERS spectrum was assigned on the basis of literature‐reported vibrational assignments of lignin and its models. Based on significant changes in Raman features, we propose that the lignin is strongly adsorbed on silver. To determine whether SERS of lignin can be obtained directly from wood without its isolation, Wiley‐milled spruce wood (WMW) adsorbed on silver was studied. The results indicated that not only the surface‐enhancement effect was successfully induced in the WMW, but that its spectrum was similar to MWL SERS. Moreover, for WMW, no signals from the carbohydrate components were observed, and therefore, lignin was detected selectively. This nano‐ and microparticle‐based molecularly specific method is expected to make a significant contribution in identifying and investigating lignin in various lignin‐containing materials. Published in 2009 by John Wiley & Sons, Ltd.
Surgical techniques for the treatment of nasal valve collapse
Authors: Spielmann Patrick M. , White Paul S. , Hussain S. S. M.
Published: May 2009

Objectives/Hypothesis:

To critically evaluate the surgical treatment strategies for nasal valve collapse.

Methods:

A systematic review of studies to treat nasal valve collapse, using surgical methods, from 1970 to 2008. A search of EBM reviews, MEDLINE, and EMBASE was performed using the following search terms: “nasal valve collapse” AND “alar collapse,” “nasal valve insufficiency,” “alar insufficiency,” and “functional rhinoplasty.” The following outcome measures were sought: subjective symptom relief, cosmetic outcome, and objective measurements of nasal airway patency. The following were inclusion criteria: at least 10 patients in each study, stated aim to improve airway obstruction, and a minimum of 1 month follow‐up for every patient.

Results:

Our search identified 98 papers, which were then retrieved and analyzed. Of these, 43 met the inclusion criteria. No randomized controlled trials exist; one trial presented level IIIb evidence, but all other studies were classed as level IV. Seven authors present objective measurements of nasal airflow or cross‐sectional area, and four authors present validated outcome measures.

Conclusions:

A variety of focussed surgical techniques are described to deal with nasal valve collapse. We could find no randomized controlled trials on nasal valve surgery. Research in nasal valve surgery is frequently driven by technical description of surgical technique rather than the establishment of evidence of long‐term patient benefit. Although our understanding of the role of the nasal valve in the pathophysiology of nasal obstruction has improved vastly, the myriad of surgical techniques described perhaps reflects our uncertainty in choice of technique and in degree of patient benefit. Laryngoscope, 2009
Characterization of raised phonation in an evoked rabbit phonation model
Authors: Swanson Erik R. , Abdollahian Davood , Ohno Tsunehisa , Ge Pingjiang , Zealear David L. , Rousseau Bernard
Published: May 2009

Objectives/Hypothesis:

Our laboratory has developed an in vivo rabbit model to investigate the effects of phonation on expression and turnover of the vocal fold extracellular matrix. As a logical outgrowth of this research to include phonotrauma in the present study, we investigated the hypothesis that an increase in airflow rate delivered to the glottis produces a change in glottal configuration and an increase in mean phonation intensity.

Study Design:

Prospective animal study.

Methods:

Six New Zealand white breeder rabbits weighing 3 to 5 kg were used in this study. A rigid endoscope and camera were used to document glottal configuration. Acoustic signals of modal and raised phonation were recorded and digitized. Two separate one‐way repeated measures analysis of variance (ANOVA) tests were used to investigate within subject differences in phonation intensity and fundamental frequency between modal and raised phonation.

Results:

Phonation intensity was 54.19 dB SPL (6.21 standard deviations [SD]) during modal phonation, and 60.31 dB SPL (5.68 SD) during raised phonation. Endoscopic images revealed a convergent glottis, with greater separation of the vocal folds during raised phonation. Results of ANOVA revealed a significant within subjects effect for phonation intensity (P = .011). Pairwise comparisons revealed that phonation intensity increased significantly during raised phonation, compared to modal phonation (P = .008). No differences in mean fundamental frequency were observed between phonation conditions.

Conclusions:

Improved understanding of factors that control phonation output in the in vivo rabbit model will result in improved capabilities to match phonation dose across animals and provide immediate direction to future biochemical studies. Laryngoscope, 2009
Electrospun Hybrid Nanofibers Based on Chitosan or N‐Carboxyethylchitosan and Silver Nanoparticles
Authors: Penchev Hristo , Paneva Dilyana , Manolova Nevena , Rashkov Iliya
Published: May 2009

Hybrid nanofibers from chitosan or N‐carboxyethylchitosan (CECh) and silver nanoparticles (AgNPs) were prepared by electrospinning using HCOOH as a solvent. AgNPs were synthesized in situ in the spinning solution. HCOOH slowed down the cross‐linking of the polysaccharides with GA enabling the reactive electrospinning in the presence of poly(ethylene oxide) (PEO). EDX analyses showed that AgNPs are uniformly dispersed in the nanofibers. Since AgNPs hampered the cross‐linking of chitosan and CECh with GA in the hybrid fibers, the imparting of water insolubility to the fibers was achieved at a second stage using GA vapors. The surface of chitosan/PEO/AgNPs nanofibers was enriched in chitosan and 15 wt.‐% of the incorporated AgNPs were on the fiber surface as evidenced by XPS.

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Gallic Acid‐Loaded Electrospun Poly(L‐Lactic Acid) Fiber Mats and their Release Characteristic
Authors: Chuysinuan Piyachat , Chimnoi Nitirat , Techasakul Supanna , Supaphol Pitt
Published: May 2009

Ultra‐fine fiber mats of poly(L‐lactic acid) containing gallic acid were prepared by electrospinning from gallic acid‐containing PLLA solution in 7:3 v/v dichloromethane (DCM)/N,N‐dimethylformamide (DMF). The amount of the as‐loaded gallic acid was 40% w/w (based on the weight of PLLA in the solution) or 28.6 wt.‐% (based on the weight of the resulting fiber mats). Both the neat and the gallic acid‐loaded PLLA fibers were smooth, with the average diameters of 965 and 843 nm, respectively. No aggregates of gallic acid were observed on the fiber surface and the actual amount of gallic acid in the gallic acid‐loaded PLLA fiber mats, determined in the acetate buffer, the citrate‐phosphate buffer, and the normal saline, was 26.3, 27.1, and 24.6 wt.‐%. The cumulative amount of gallic acid released from the gallic acid‐loaded PLLA fiber mats was greatest in the normal saline, followed by those in the citrate‐phosphate and the acetate buffer, respectively. Lastly, the free radical scavenging activity, based on the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay, of the as‐loaded and the as‐released gallic acid remained active.

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Calcium Phosphate Crystallization on Electrospun Cellulose Non‐Woven Fabrics Containing Synthetic Phosphorylated Polypeptides
Authors: Hayashi Shinya , Ohkawa Kousaku , Yamamoto Hiroyuki , Yamaguchi Mina , Kimoto Shigenari , Kurata Shigeaki , Shinji Hisaaki
Published: May 2009

The preparation of electrospun non‐woven fabrics composed of cellulose and synthetic phosphorylated polypeptides, copoly[Ser(PO3H2)XAspY]s (X:Y = 100:0, 75:25, 50:50, 25:75), is described. The non‐wovens were subjected to an alternate immersion in CaCl2and Na2HPO4solutions to induce crystallization of calcium phosphate. The deposited calcium phosphate crystals were analyzed by means of EDX analysis and WXRD. The amounts of calcium phosphate deposition are greater for the cellulose non‐woven fabrics containing copoly[Ser(PO3H2)XAspY] than those of cellulose‐only non‐woven fabrics. These results indicate that copoly[Ser(PO3H2)XAspY] can entrap Ca2+ions around the fine fiber matrix to accelerate crystallization of the calcium phosphate.

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A Theoretical and Experimental Study on Solubility of Curatives in Rubbers
Authors: Guo Rui , Talma Auke G. , Datta Rabin N. , Dierkes Wilma K. , Noordermeer Jacques W. M.
Published: May 2009

The current study provides indications for improving the properties of dissimilar rubber blends. As solubility is a key factor for the distribution and a driving force for the migration of curatives in dissimilar rubber blends, it is of importance to have precise data of their solubilities. The solubilities of (insoluble) sulfur and the accelerators CBS, MBT and DCBS are measured at RT and at 60 °C, in lightly crosslinked SBR, NBR and EPDM. The experimental results correlate well with calculated solubility parameters, as determined using the method of Hoftijzer and van Krevelen.

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Poly(aryleneethynylene)s
Authors: Bunz Uwe H. F.
Published: May 2009

Poly(aryleneethynylene)s (PAE) are easily synthesized, chemically stable, and color‐responsive towards their surroundings. These superbly chromic polymers are attractive as active transducers in sensors and advanced organic electronic devices. PAEs are generally fluorescent with emission maxima ranging from 420–600 nm, and can be either water‐ or organo‐soluble. PAEs from linear building blocks are rigid rod molecules and display a host of supramolecular arrangements in solution and in the solid state. The poly(para‐phenyleneethynylene)s (PPE) are lyotropic or thermotropic smectic liquid crystalline. In the solid state, PPEs display lamellar supramolecular structures that lead to distinct stranded nanoscale morphologies. The spectroscopy and the optical properties of the PAEs and in particular of the PPEs are dominated by their conformation, which is influenced by solid‐state packing, solvent, temperature and other factors. The presence of twisted and planar forms and their interconversion leads to attractive structure/property relationships; PAEs are of use as ingredients for advanced supramolecular materials.

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All‐Conjugated, Rod‐Rod Block Copolymers‐Generation and Self‐Assembly Properties
Authors: Scherf Ullrich , Adamczyk Sylwia , Gutacker Andrea , Koenen Nils
Published: May 2009

Based on their rigid‐rod structure all‐conjugated, rod‐rod block copolymers show a preferred tendency to self‐assemble into low‐curvature vesicular or lamellar nanostructures independent from their specific chemical structure and composition. This unique and attractive behaviour is clearly illustrated in a few examples of such all‐conjugated block copolymers. The resulting nanostructured heteromaterials may find applications in electronic devices or artificial membranes.

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