Carboxylic acid to thioamide hydrogen bonding

Hydrogen bonding in enantiomeric versus racemic mono-carboxylic acids; a case study of 2-phenoxypropionic acid.

The structural and thermodynamic backgrounds for the crystallization behaviour of racemates have been investigated using 2-phenoxypropionic acid (PPA) as an example. The racemate of PPA behaves normally and forms a racemic compound that has a higher melting point and is denser than the enantiomer. Low-temperature crystal structures of the pure enantiomer, the enantiomer cocrystallized with n-al...

(±)-trans-3-Oxo-1,2,3,4,4a,9,10,10a-octa­hydro­phenanthrene-10a-carboxylic acid: catemeric hydrogen bonding in a δ-keto acid

The title compound, C(15)H(16)O(3), aggregates as hydrogen-bonded catemers progressing from each carboxyl to the ketone of a screw-related neighbor [O⋯O = 2.6675 (14) Å and O-H⋯O = 170°]. Two parallel centrosymmetrically related single-strand hydrogen-bonding helices proceed through the cell in the b-axis direction. The packing includes three inter-molecular C-H⋯O=C close contacts, involving bo...

Hydrogen bonding

molecules to evolve in the test tube. With the discovery of catalytic RNA, and advances in nucleic acid amplification techniques such as the polymerase chain reaction, it became possible to construct laboratory systems that allow the Darwinian evolution of functional RNA (and later DNA) molecules. This is not evolution based on natural selection, but rather directed evolution based on selection...

Recognition of nucleic acid bases and base-pairs by hydrogen bonding to amino acid side-chains.

Sequence-specific protein-nucleic acid recognition is determined, in part, by hydrogen bonding interactions between amino acid side-chains and nucleotide bases. To examine the repertoire of possible interactions, we have calculated geometrically plausible arrangements in which amino acids hydrogen bond to unpaired bases, such as those found in RNA bulges and loops, or to the 53 possible RNA bas...

Computational study of three dimensional potential energy surfaces in intermolecular hydrogen bonding of cis-urocanic acid