Encapsulated Carboxylic Acid Dimers with Compressed Hydrogen Bonds

Ajami, Dariush; Tolstoy, Peter M.; Dube, Henry; Odermatt, Severin; Koeppe, Benjamin; Guo, Jing; Limbach, Hans−Heinrich; Rebek, Julius

doi:10.1002/anie.201002182

Cited by 50 publications

(35 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All self-associates (homodimers and homotrimers) featured cooperativity, namely, isotopologs HD (for dimers), HHD, and HDD (for trimers) gave rise to the signals in higher fields than the signals of corresponding non-deuterated species. Such cooperativity was reported previously for self-associates of phosphinic and phosphoric acids [14,15] and for carboxylic acids [17,39]. However, the situation was different for some heterocomplexes.…”

Section: Cooperativity and Anticooperativitysupporting

confidence: 76%

“…Another interesting feature of heterotrimers is associated with the mutual influence of hydrogen bonds. In all cases hydrogen bonds in the cycle are arranged in a head-to-tail motif, ···O=P-O-H···O=P-O-H··· and thus one could expect a cooperative coupling of these bonds (similar to the case of cyclic dimers of carboxylic acids [17,39] or self-associates of phosphinic and phosphoric acids [14,15]). However, the signs of vicinal H/D isotope effects are evidence of an effective anticooperativity: deuteration (lengthening) of one of the hydrogen bonds leads to the shortening of the neighboring ones.…”

Section: Discussionmentioning

confidence: 99%

“…The δH values for heterocomplexes were larger in average than those for homocomplexes; from this observation one could conclude that the hydrogen bonds were stronger and it would be interesting to check if the equilibrium between homo-and heterocomplexes would be shifted towards the latter in the gas phase as well. To our knowledge, the value of 17 ppm is the largest chemical shift value for an intermolecular hydrogen bond in neutral self-associate of an acid, including the POOH-and COOH-containing ones (an intramolecular bonding [38] or strong steric hindrance [39] might lead to larger values still).…”

Section: Hydrogen Bond Strengthmentioning

confidence: 92%

See 2 more Smart Citations

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

et al. 2020

Self Cite

View full text Add to dashboard Cite

Hydrogen-bonded heterocomplexes formed by POOH-containing acids (diphenylphosphoric 1, dimethylphosphoric 2, diphenylphosphinic 3, and dimethylphosphinic 4) are studied by the low-temperature (100 K) 1H-NMR and 31P-NMR using liquefied gases CDF3/CDF2Cl as a solvent. Formation of cyclic dimers and cyclic trimers consisting of molecules of two different acids is confirmed by the analysis of vicinal H/D isotope effects (changes in the bridging proton chemical shift, δH, after the deuteration of a neighboring H-bond). Acids 1 and 4 (or 1 and 3) form heterotrimers with very strong (short) H-bonds (δH ca. 17 ppm). While in the case of all heterotrimers the H-bonds are cyclically arranged head-to-tail, ···O=P–O–H···O=P–O–H···, and thus their cooperative coupling is expected, the signs of vicinal H/D isotope effects indicate an effective anticooperativity, presumably due to steric factors: when one of the H-bonds is elongated upon deuteration, the structure of the heterotrimer adjusts by shortening the neighboring hydrogen bonds. We also demonstrate the formation of cyclic tetramers: in the case of acids 1 and 4 the structure has alternating molecules of 1 and 4 in the cycle, while in case of acids 1 and 3 the cycle has two molecules of 1 followed by two molecules of 3.

show abstract

Section: Cooperativity and Anticooperativitysupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Hydrogen Bond Strengthmentioning

confidence: 92%

See 1 more Smart Citation

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Another two peaks at ı 4.04 and 3.30 coupled with C at ı 62.6 were also thought to be from C6. The shifting of these two C6 and H6 peaks of CNF 1.5 was thought to be due to the strong hydrogen bond between the non-oxidized C6 OH and the C6 carbonyl O of partially oxidized CNF 1.5 (Abraham & Mobli, 2007;Ajami et al, 2011;Grzesiek, Cordier, Jaravine, & Barfield, 2004;Moulthrop, Swatloski, Moyna, & Rogers, 2005). Other peaks present in CNF1.5 were assigned as follows: H3 at ı 3.75, C3 at ı 75.7, H4 at ı 3.66, C4 at ı 80.1, H5 at ı 3.52; C5 at ı 74.2.…”

Section: Nmr Characterization Of Nanocellulosementioning

confidence: 99%

1D and 2D NMR of nanocellulose in aqueous colloidal suspensions

Jiang

Dallas

Ahn

et al. 2014

Carbohydrate Polymers

View full text Add to dashboard Cite

a b s t r a c tThis is the first report on surface structural elucidation of individual nanocellulose as colloidal suspensions by 1D 1 H, 2D heteronuclear single quantum coherence (HSQC) as well as 13 C nuclear magnetic resonance (NMR).1 H NMR of rice straw CNCs (4.7 nm thick, 143 nm long, 0.04 sulfate per AG or 19.0% surface hydroxyl to sulfate conversion) resembled that of homogeneous cellulose solution. Conventional 2D HSQC NMR of CNC, CNF 1.5 (2-14 nm thick, several micrometers long, 0.10 COOH per AG) and CNF10 (2.0 nm thick, up to 1 m long, 0.28 COOH per AG) gave H1:H2 ratios of 1.08:1, 0.97:1 and 0.94:1, respectively, all close to the theoretical 1:1 value for cellulose. The H1:H6 ratios determined from 2D HSQC NMR for CNCs, CNF1.5 and CNF10 were 1:1.47, 1:0.88 and 1:0.14, respectively, and corresponded to 26%, 56% and 93% C6 primary hydroxyl conversion to sulfate and carboxyl groups, consistent with, but more sensitive than those by conductometric titration and X-ray diffraction. Both 1 H and 2D HSQC NMR data confirm that solution-state NMR detects nanocellulose surface carbons and protons primarily, validating this technique for direct surface characterization of nanocellulose in aqueous colloidal suspensions, presenting a sensitive and meaningful NMR tool for direct characterizing individual nanocellulose surfaces in never-dried state.

show abstract

“…Faced with the need for a short and efficient synthesis of highly 1‐ 13 C enriched cinnamic acids for 13 C NMR studies in dilute solutions, we reconsidered the Perkin reaction with a focus on the efficiency of the product integration of valuable carboxylic moieties. The key idea is to employ a carboxylic anhydride consisting of carboxylic groups lacking α protons.…”

Section: Introductionmentioning

confidence: 99%

An efficient Perkin synthesis of ¹³C‐labelled cinnamic acids from acetic acid as the source of the rare isotope

Lenz

Koeppe

Tolstoy

et al. 2019

Labelled Comp Radiopharmac

Self Cite

View full text Add to dashboard Cite

This practitioner protocol describes an efficient Perkin synthesis of 1-13 C-palkylcinnamic acids from 1-13 C-acetic acid and the benzaldehyde with caesium carbonate and pivalic anhydride as reagents. Our new method employing the nonenolizable pivalic anhydride as the condensation agent avoids the minimum threefold excess of identically labelled carboxylate moieties (in both acid and anhydride) required in a conventional Perkin synthesis to prevent isotope dilution. More generally, this variation of the Perkin synthesis broadens the scope of that classic reaction to valuable carboxylic acid components.

show abstract

Encapsulated Carboxylic Acid Dimers with Compressed Hydrogen Bonds

Cited by 50 publications

References 46 publications

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

1D and 2D NMR of nanocellulose in aqueous colloidal suspensions

An efficient Perkin synthesis of ¹³C‐labelled cinnamic acids from acetic acid as the source of the rare isotope

Contact Info

Product

Resources

About

Encapsulated Carboxylic Acid Dimers with Compressed Hydrogen Bonds

Cited by 50 publications

References 46 publications

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

1D and 2D NMR of nanocellulose in aqueous colloidal suspensions

An efficient Perkin synthesis of 13C‐labelled cinnamic acids from acetic acid as the source of the rare isotope

Contact Info

Product

Resources

About

An efficient Perkin synthesis of ¹³C‐labelled cinnamic acids from acetic acid as the source of the rare isotope