A Highly Stable, Six-Hydrogen-Bonded Molecular Duplex

Zeng, Huaqiang; Miller, Rebecca S.; Flowers, Robert A.; Gong, Bing

doi:10.1021/ja9942742

Cited by 201 publications

(137 citation statements)

References 33 publications

Supporting

Mentioning

131

Contrasting

Unclassified

Order By: Relevance

“…Experimental analogs include adenine-and thymine-derived nucleobase interactions, 42 diamido-naphthyridine complexes with urea (ADDA:DAAD), 43 and oligoamide duplexes (ADAADA:DADDAD). 18 …”

Section: Scopementioning

confidence: 99%

“…12,13 Over the last decade, stronger and more directional multiple H-bonding groups have been developed. [14][15][16][17][18][19][20][21][22][23] These functional groups typically employ an array of complementary or self-complementary hydrogen bonds. For example, the ureidopyrimidinone group contains four hydrogen-bond sites and reversibly dimerizes with an association constant K a exceeding 10 6 M À1 in chloroform.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Phase behavior predictions for polymer blends containing reversibly associating endgroups

Anthamatten¹

2007

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

A mean field model is developed to predict how polymer-polymer miscibility changes if polymers are functionalized with noncovalent, reversibly binding endgroups. The free-energy model is based on the Flory-Huggins mixing theory and has been modified using Painter's association model to account for equilibrium selfassociation of endgroups. Model input parameters include the length of polymer chains, a temperature-dependent interaction parameter, and a temperature-dependent equilibrium constant for each type of associating endgroup. The analysis is applied to 12 possible blend combinations involving self-complementary interactions and seven combinations involving hetero-complementary [i.e. donor-acceptor (DA)] interactions. Combinations involve both monofunctional and telechelic associating chains. Predicted phase diagrams illustrate how self-complementary interactions can stabilize two-phase regions and how DA interactions can stabilize single phase regions. The model is a useful tool in understanding the delicate balance between the combinatorial entropy of mixing polymer chains, the repulsive interactions between dissimilar polymers, and the additional enthalpic and entropic changes due to endgroup association of chain ends.

show abstract

“…Experimental analogs include adenine-and thymine-derived nucleobase interactions, 42 diamido-naphthyridine complexes with urea (ADDA:DAAD), 43 and oligoamide duplexes (ADAADA:DADDAD). 18 …”

Section: Scopementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase behavior predictions for polymer blends containing reversibly associating endgroups

Anthamatten¹

2007

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

“…Figure 2 shows solid-state structures for 2 and 3. 7 The majority of the molecules in the unit cell of 2 adopt a syn-syn conformation with intramolecular hydrogen bonds between the hydroxy and carbonyl groups (O‚‚‚O 2.55-2.57 Å). In this structure, two molecules of 2 in the syn-syn conformation bind the carbonyl oxygens of a third molecule of the receptor (Supporting Information).…”

mentioning

confidence: 99%

Conformational Control of Transmembrane Cl^- Transport

et al. 2007

View full text Add to dashboard Cite

Due to their biological importance, the complexation, sensing, and transport of anions are attracting increasing attention. 1,2 A variety of receptors based on the isophthalamide skeleton (e.g., 1 in Figure 1) have been studied, as these systems are easy to make and are effective anion receptors in organic solution. 3,4 Two strategies to improve the affinity and selectivity of anion receptors are to increase the acidity of hydrogen bond donors and/or to build more rigid scaffolds. The first strategy may, in some cases, result in deprotonation of the receptor by basic anions, 5 whereas the second strategy may require involved syntheses. We report here a host designed to have both enhanced hydrogen bond donor strength and conformational preorganization. Intramolecular hydrogen bonds make isophthalamide 2 a potent anion binder and an effective transmembrane transporter of Cl -.Experiment and calculations show that isophthalamides such as 1 prefer a syn-anti conformation about the 1,3-diamide unit. 6 As this conformation lacks convergent hydrogen bond donors, it is not optimal for anion binding. We reasoned that the -OH groups in 2 should form intramolecular hydrogen bonds with the amide carbonyls to stabilize the syn-syn conformation and favor the cleft needed for anion binding. 3 Compound 3 is a negative control, as its C4, C6-OMe groups should hydrogen bond with the N-H protons to stabilize the anti-anti conformation and preclude anion binding. Figure 2 shows solid-state structures for 2 and 3. 7 The majority of the molecules in the unit cell of 2 adopt a syn-syn conformation with intramolecular hydrogen bonds between the hydroxy and carbonyl groups (O‚‚‚O 2.55-2.57 Å). In this structure, two molecules of 2 in the syn-syn conformation bind the carbonyl oxygens of a third molecule of the receptor (Supporting Information). Compound 3 exists only in the anti-anti conformation. The amide and methoxy substituents are coplanar and involved in intramolecular hydrogen bonds (N‚‚‚O 2.67-2.68 Å). NMR data confirmed that these conformations for 2 and 3 also predominate in solution. In CD 3 CN, the 1 H NMR resonance for the OH protons in 2 was far downfield (δ 13.50), consistent with involvement in hydrogen bonding. Moreover, the chemical shift for the aromatic hydrogen between the amide side chains moved progressively downfield (δ 7.80, 8.18, and 8.70) in going from 2 to 1 to 3, reflecting an increasing preference for conformations wherein the hydrogen is syn to the deshielding carbonyls. The NMR signal for the N-H proton in dimethoxy 3 (δ 7.71) was shifted downfield relative to the N-H protons for 1 and 2 (δ 7.10), presumably due to involvement in intramolecular hydrogen bonds. This structural data indicated that 2 is predisposed toward a syn-syn orientation, whereas 3 favors an anti-anti orientation.Addition of Cl -, Br -, and I -anions to 1 and 2 in CD 3 CN resulted in downfield shifts of the N-H and H2 signals, whereas little change was observed for the O-H signal in 2. These data suggest that 1 and 2 bind anions wit...

show abstract

“…[39][40][41][42][43] When a proton is involved in hydrogen bond, its electrons are shared by two electronegative elements and its electron density is hence decreased. Therefore, the proton is deshielded and comes into resonance at a lower field.…”

Section: Hydrogen Bond Analysismentioning

confidence: 99%

Synthesis, helicity, thermal stability, and low infrared emissivity of optically active polyacetylenes carrying tyrosine pendants

Chen

Zhou

et al. 2014

Designed Monomers and Polymers

View full text Add to dashboard Cite

Optically active polyacetylenes (LPA and DPA) and racemic polyacetylenes (RPA) were prepared by the polymerization of N-propioloyl-tyrosine methyl esters that derived from chiral and racemic tyrosine. All the polymers were characterized by Fourier transform infrared spectroscopy, 1 H NMR, 13 C NMR, gel permeation chromatography, thermogravimetric analysis, UV-vis spectroscopy, and circular dichroism spectroscopy; furthermore, the infrared emissivity values were also investigated. Both LPA and DPA possessed the helical conformations and a higher degree of intra-and interchain hydrogen bonds compared with RPA, which presented irregular polymer chain. The thermal stability of LPA and DPA was higher than that of RPA due to the helical conformations, which could be easy to form a high degree of intra-and interchain hydrogen bonds in the structure. Therefore, LPA and DPA exhibited lower infrared emissivity values (8-14 μm) than that of RPA, which resulted from the helical conformations and a higher degree of intra-and interchain hydrogen bonds.

show abstract

A Highly Stable, Six-Hydrogen-Bonded Molecular Duplex

Cited by 201 publications

References 33 publications

Phase behavior predictions for polymer blends containing reversibly associating endgroups

Phase behavior predictions for polymer blends containing reversibly associating endgroups

Conformational Control of Transmembrane Cl^- Transport

Synthesis, helicity, thermal stability, and low infrared emissivity of optically active polyacetylenes carrying tyrosine pendants

Contact Info

Product

Resources

About

A Highly Stable, Six-Hydrogen-Bonded Molecular Duplex

Cited by 201 publications

References 33 publications

Phase behavior predictions for polymer blends containing reversibly associating endgroups

Phase behavior predictions for polymer blends containing reversibly associating endgroups

Conformational Control of Transmembrane Cl- Transport

Synthesis, helicity, thermal stability, and low infrared emissivity of optically active polyacetylenes carrying tyrosine pendants

Contact Info

Product

Resources

About

Conformational Control of Transmembrane Cl^- Transport