Oligoindole-Based Foldamers with a Helical Conformation Induced by Chloride

Chang, Kihun; Kang, Byung Nam; Lee, Min Hee; Jeong, Kyu Sung

doi:10.1021/ja0547984

Cited by 183 publications

(69 citation statements)

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“…[1][2][3][4][5] Potential applications in the separation and extraction of anionic species, in the development of new sensing systems and in the design of new compounds that may have potential biological activity has driven the synthesis of a plethora of receptors 25 containing amides and thioamides, pyrroles and indoles, ureas and thioureas, ammonium, guanidinium and imidazolium moieties. 6,7 Indole is employed by Nature in sulfate binding protein 8 and in the enzymatic active site of haloalkane dehalogenase 9 30 to bind anions, however research in area of indole-based anion receptors [10][11][12][13][14][15][16][17][18][19][20] is still at an early stage compared to the range of anion receptors based on pyrrole. 21 The recognition and sensing properties of indole can be effectively regulated by appending additional hydrogen bond donors to the indole 35 skeleton.…”

Section: Introductionmentioning

confidence: 99%

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

et al. 2009

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The conformational preorganization and anion-induced conformational changes of indole-based receptors functionalized with amido group at C2 and a variety of amido, urea and thiourea moieties at C7 have been studied by the means of NMR spectroscopy. NOE experiments showed that antianti orientation across C2-C2α and C7-N7α bonds is preferred for receptors 1-4 in acetone 10 solution in the absence of anions. Anion-receptor interactions have been evaluated through 1 H and 15 N chemical shift changes. In bis-amido 2,7-functionalised indoles the interaction with chloride and bromide anions primarily occurs at H1 proton. The formal introduction of urea and thiourea moieties increases the number of hydrogen bond donor sites which manifests itself in distribution of halide-receptor interactions among H1, H7α and H7γ protons. Acetate anions also interact 15 strongly with indole and urea NH donor groups, whereas nitrate anions interact solely with H7α and H7γ urea/thiourea protons. NOE enhancements in the presence of anions revealed that anionreceptor complexes favor syn-syn conformation of C2 and C7 substituents.

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Section: Introductionmentioning

confidence: 99%

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

et al. 2009

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“…[8,13] While the various rotamers of 1 are equally populated, NOESY contacts in the presence of Bu 4 N + Cl À indicate that the folding depicted in Figure 1 (Figure 2 b).…”

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confidence: 97%

1,2,3‐Triazole CH⋅⋅⋅Cl⁻ Contacts Guide Anion Binding and Concomitant Folding in 1,4‐Diaryl Triazole Oligomers

et al. 2008

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Manipulation of weak intermolecular interactions guides the rational design [1] of sensors, drugs, and foldamers-synthetic, [2] nonnatural backbones that fold into an ordered, biomimetic array. 1,4-Substituted 1,2,3-triazoles, which are readily accessible through the Cu I -catalyzed Huisgen 1,3-dipolar cycloaddition of azides and alkynes, [3] are seemingly universal ligation tools [4] whose capacity for independent function has received far less attention. Recent reports, however, indicate that the size and dipole moment ( % 5 D) of triazoles make them interesting candidates for amide bond surrogates, [5] and Arora and co-workers have reported the contributions of triazoles to the conformational preferences of peptidotriazole oligomers. [6] We hypothesized that oligomer 1 would fold in a manner similar to other linear, flexible oligomers [7] to provide a model cavity by which to explore the intermolecular interactions between the electropositive CH side of 1,4-triazoles and electron-rich guests such as anions ( Figure 1). Our expectations were buoyed by previous reports of anion-induced folding, [8,9] in particular by a recent demonstration by Jeong and co-workers [8] that the folding of oligoindoles can be directed through a helical arrangement of NH···anion hydrogen bonds. Herein, we report 1) that 1:1 interactions between diaryl triazoles and chloride ions in acetone are directional and sufficiently strong as to be observable by 1 H NMR spectroscopy, 2) that the strength of the interaction increases with the generation of triazole-containing oligomer, and 3) that CH···anion contacts guide the folding of aryl triazole oligomers in solution and in the solid state.While the "click" coupling of alkyl azides with alkynes is highly efficient, [10] the formation of diaryl triazoles has, until recently, been relatively more difficult and less efficient. [11] Nonetheless, under modified conditions, the Cu I -catalyzed cycloaddition produces acceptable yields of the desired 1,4-diaryl-1,2,3-triazole-containing compounds 1-3. A tetraethylene glycol unit was introduced outside of the cavity for solubility.Oligomer 1 has appreciable conformational freedom only around the arene-triazole single bonds. Molecular modeling [12] suggested no significant preference for a particular rotamer, a prediction that is supported by NOESY spectra of 1 in [D 6 ]acetone (Figure 2 a). Modeling studies also show that complexation of 1 with Cl À aligns the electropositive triazole CH units toward the interior of a helix, within which the Cl À is bound.The computer modeling holds true in solution, where the chloride-induced folding of 1 is revealed by 1 H NMR spectroscopy. The 1 H NMR spectrum of 1 changes considerably upon the addition of tetrabutylammonium chloride

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“…Металлокатализ солями одновалентной меди для активации тройной связи в бута-1,3-диинах 3 при кипячении в ДМФ применялся для получе-ния серии бисиндолов 9 (схема 2), которые нашли широкое применение в супрамолекулярной химии как чувствительные сенсоры и рецепторы на разнообразные анионы [12][13][14][15][16][17][18]. Реакция циклизации с образованием бисбензофурана 10 протекала при электрофильной активации тройной связи симметричного бис(2-метоксифенил)бута-1,3-диина 4 под действием п-толуолсульфокислоты (PTSA) [19].…”

Section: получение 2-замещенных гетероцикловunclassified

Intramolecular cyclizations of functionalized diynes

Danilkina

Kulyashova

Балова

2012

Chem Heterocycl Comp

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Аннотация. В обзоре рассматриваются примеры внутримолекулярных цикли-заций с участием функционализированных диацетиленов. Циклизации протекают с участием одной из тройных связей с образованием этинилзамещенных гетеро-циклов или двух тройных связей, что используется в синтезе поликонденсирован-ных гетероциклических систем и ансамблей.Ключевые слова: бута-1,3-диины, внутримолекулярные циклизации, бисцик-лизации, этинилзамещенные гетероциклы, индолы, бензофураны, бензотиофены, индозолы, аннелированные поли гетероциклы.

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Oligoindole-Based Foldamers with a Helical Conformation Induced by Chloride

Cited by 183 publications

References 20 publications

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

1,2,3‐Triazole CH⋅⋅⋅Cl⁻ Contacts Guide Anion Binding and Concomitant Folding in 1,4‐Diaryl Triazole Oligomers

Intramolecular cyclizations of functionalized diynes

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Oligoindole-Based Foldamers with a Helical Conformation Induced by Chloride

Cited by 183 publications

References 20 publications

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

1,2,3‐Triazole CH⋅⋅⋅Cl− Contacts Guide Anion Binding and Concomitant Folding in 1,4‐Diaryl Triazole Oligomers

Intramolecular cyclizations of functionalized diynes

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1,2,3‐Triazole CH⋅⋅⋅Cl⁻ Contacts Guide Anion Binding and Concomitant Folding in 1,4‐Diaryl Triazole Oligomers