Aromatic Compounds as Donor Molecules in Hydrogen Bonding<sup>1</sup>

Tamres, Milton

doi:10.1021/ja01133a047

Cited by 126 publications

(61 citation statements)

References 3 publications

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“…What is the origin of this discrepancy? In an earlier work [1] it was noted that in some proteins containing Pro-Pro cis bond, the first Pro residue was involved in a CHÁ Á Áp interaction [12][13][14][15][16] with Phe side-chain following the second Pro. However, there were other examples where no such interaction was present in Pro-Pro-Phe cis units (Fig.…”

Section: Introductionmentioning

confidence: 99%

Enhanced stability of cis Pro‐Pro peptide bond in Pro‐Pro‐Phe sequence motif

2007

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Identification of sequence motifs that favor cis peptide bonds in proteins is important for understanding and designing proteins containing turns mediated by cis peptide conformations. From 1 H NMR solution studies on short peptides, we show that the Pro-Pro peptide bond in Pro-Pro-Phe almost equally populates the cis and trans isomers, with the cis isomer stabilized by a CHÁ Á Áp interaction involving the terminal Pro and Phe. We also show that Phe is over-represented at sequence positions immediately following cis Pro-Pro motifs in known protein structures. Our results demonstrate that the Pro-Pro cis conformer in Pro-Pro-Phe sequence motifs is as important as the trans conformer, both in short peptides as well as in natively folded proteins.

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Section: Introductionmentioning

confidence: 99%

Enhanced stability of cis Pro‐Pro peptide bond in Pro‐Pro‐Phe sequence motif

2007

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“…Ph4Pf and BPh4-ions are believed to disrupt the water structure (41)(42)(43)(44)51), although these conclusions are questioned by some workers (45). Since at present there is no clear-cut way to classify solutes as structure makers or breakers, different approaches often lead to different conclusions.…”

Section: Resultsmentioning

confidence: 99%

Enthalpies of solution and single ion enthalpies of transfer from water to dioxane–water mixtures

Bhatnagar¹

1976

Can. J. Chem.

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OM N. BHAT~AGAR Can J. Chem 54, 3487 (1976) Standard enthalples of solutions of sodlum bromlde, potasslum bronude, tetrabutyl phosphonium brom~de, tetraphenyl phosphoniu~n bromide, and sodlum tetraphenyl boron have been measured In 20C,, 44 5' ,, and 64 5(, dloxane-water mlxture. On the extra thermodynam~c assumption AAH,(Ph4P+) = AAH,(-BPh4) slngle Ion enthalples of tranifer from water to d~oxane-water mixtures have been calculated for \ arlous Ions.OM N. BHATNAGAR. Can. J. Chem. 54, 3487 (1976). On a mesurC les enthalpies standards de solution du bromure de sodium, du bromure de potassium, du bromure de tCtrabutylphosphonium, du bromure de tCtraphCnylphosphoniun~ et du tCtraphCnylbore sodium dans des mClanges dioxanne-eau k 20C$, 44.5C; et 64.5yc. En faisant I'hypothkse thermodynamique supplCmentaire que AAH,(Ph4P+) = a~H , ( -B p h~) , on a calcule, pour divers ions, les enthalpies de transfert d'ions uniques de I'eau a des melanges dioxanne-eau.[Traduit par le journal] Introduction I have been interested in the study of thermodynamic properties of electrolyte solutions in dioxane-water mixtures for some time (1-3). The solvation enthalpies of some tetraalkyl ammonium bromides in dioxane-water mixtures were reported in a recent paper (3). It was shown that the behaviour of these electrolytes was quite similar to their behaviour in water and that the structure-making capacity of tetraalkyl ammonium ions increases with the increase in the size of the ion. Thus from the studv in dioxanewater mixtures Bu4N+ ion was found to be the most active in structure promotion. It was thought to be of interest to see how this behaviour would change (i) by changing the central atom from nitrogen to phosphorus, (ii) by changing the nature of tetraalkyl ion from aliphatic ( [ G H 9]4-) t o aromatic ([C6H5]4-), (iii) by changing the small Br-ion to a bulky -BPh4 ion.In this paper the standard enthalpies of solution, AHsO, of sodium bromide, potassium bromide, tetrabutyl phosphonium bromide (BudPBr), tetraphenyl phosphonium bromide ([C6H5]4PBr) and sodium tetraphenyl boron (NaBPh4) in 207,, 44.57,, and 64.57, dioxane-water mixtures are reported. In addition, an attempt has been made to divide the standard enthalpies of transfer AAH, from water to dioxane-water mixtures into

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“…This is the hydrogen bond occurring between a soft acid (CH) and a soft base (π group) [5][6][7]. In 1952, Tamres reported that the interaction between haloforms and a π -system is attractive [8]. Thus, CHCl 3 and CHBr 3 dissolve in aromatic solvents, exothermically.…”

Section: O H Nh 2 R Rmentioning

confidence: 99%