Hydrogen-Bonded Cyclic Dimer Formation in Temperature-Induced Reversal of Tautomerism of Salicylideneanilines

2009 ◽  
Vol 113 (9) ◽  
pp. 1822-1826 ◽  
Author(s):  
Toshikatsu Fujiwara ◽  
Jun Harada ◽  
Keiichiro Ogawa
Keyword(s):  
Cyclic Dimer ◽  
Dimer Formation ◽  
Hydrogen Bonded

scholarly journals Relationship between solid state structure and solution stability of copper(ii)–hydroxypyridinecarboxylate complexes

2019 ◽  
Vol 43 (27) ◽  
pp. 10699-10710 ◽  
Author(s):  
Nóra V. May ◽  
G. Tamás Gál ◽  
Zsolt Szentendrei ◽  
László Korecz ◽  
Zoltán May ◽  
...  
Keyword(s):  
Solid State ◽  
Cyclic Dimer ◽  
Solution Stability ◽  
State Structure ◽  
Dimer Formation ◽  
Oh Groups ◽  
Solid State Structure

More acidic –OH groups increase the solution stability of copper(ii)–hydroxypyridinecarboxylate complexes and they lose the bridging role in cyclic dimer formation.

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

2003 ◽  
Vol 59 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Henning Osholm Sørensen ◽  
Sine Larsen
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Carboxylic Acids ◽  
Crystal Packing ◽  
Cyclic Dimer ◽  
Optically Pure ◽  
Pure Enantiomer ◽  
Hydrogen Bonded

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-alkanes and the racemic acid showed that hydrogen-bonded dimers that form over crystallographic symmetry elements exist in all but the structure of the pure enantiomer. A database search for optically pure chiral mono-carboxylic acids revealed that the hydrogen-bonded cyclic dimer is the most prevalent hydrogen-bond motif in chiral mono-carboxylic acids. The conformation of PPA depends on the hydrogen-bond motif; the antiplanar conformation relative to the ether group is associated with a catemer hydrogen-bonding motif, whereas the more abundant synplanar conformation is found in crystals that contain cyclic dimers. Other intermolecular interactions that involve the substituent of the carboxylic group were identified in the crystals that contain the cyclic dimer. This result shows how important the nature of the substituent is for the crystal packing. The differences in crystal packing have been related to differences in melting enthalpy and entropy between the racemic and enantiomeric acids. In a comparison with the equivalent 2-(4-chlorophenoxy)-propionic acids, the differences between the crystal structures of the chloro and the unsubstituted acid have been identified and related to thermodynamic data.

Notizen: Preparation and Crystal Structure of the Hydrogen-Bonded Cyclic Dimer of PhP(S)[N(CH2Ph)2]OH, HN(CH2Ph)2+

1976 ◽  
Vol 31 (10) ◽  
pp. 1421-1422 ◽  
Author(s):  
T. Stanley Cameron ◽  
James D. Healy ◽  
Robert A. Shaw ◽  
Michael Woods
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Cyclic Dimer ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrogen Bonded

The structure of the title compound was determined by X-ray crystallography. The compound is a cyclic dimer with short N···O and N···S contacts.

Dimerization of Carboxylic Acids in Solution up to High Pressures and Temperatures. 2. Benzoic Acid

1987 ◽  
Vol 42 (4) ◽  
pp. 406-412 ◽  
Author(s):  
R. Barraza ◽  
E. M. Borschel ◽  
M. Buback
Keyword(s):  
Benzoic Acid ◽  
Quantitative Measurement ◽  
High Pressures ◽  
Equilibrium Constants ◽  
Cyclic Dimer ◽  
Maximum Pressure ◽  
Dilute Solution ◽  
High Pressures And Temperatures ◽  
Lower Temperature ◽  
Hydrogen Bonded

Benzoic acid in dilute solution of n-heptane and of CCl4 is studied via high-pressure hightemperature IR spectroscopy on the C = O and O - H stretching fundamentals. Lambert-Beer’s law is shown to be valid for the C = O modes of the acid monomer and of the hydrogen-bonded cyclic dimer, which enables the quantitative measurement of the dimerization equilibrium to a maximum pressure of 2 kbar and up to 175 °C. At identical pressure and temperature the dimerization equilibrium constant is larger in n-heptane than in CCl4. From the monomer-cyclic dimer equilibrium constants the pressure dependence of the dimerization enthalpy is determined and compared with direct information on both species as derived from their O - H fundamental mode absorption. Toward lower temperature the dimerization volume is decreasingly negative and, in CCl4 solution, ΔV even changes sign around 40 °C. Increasing pressure thus favours the dissociation of the hydrogen-bonded dimer into benzoic acid monomer molecules at ambient temperature.

Direct observation of the cyclic dimer in liquid acetic acid by probing the CO vibration with ultrafast coherent Raman spectroscopy

2014 ◽  
Vol 16 (33) ◽  
pp. 18010-18016 ◽  
Author(s):  
Matthias Lütgens ◽  
Frank Friedriszik ◽  
Stefan Lochbrunner
Keyword(s):  
Raman Spectroscopy ◽  
Acetic Acid ◽  
Direct Observation ◽  
Cyclic Dimer ◽  
Vibrational Bands ◽  
Coherent Raman ◽  
Hydrogen Bonded

The coalescing CO vibrational bands of liquid acetic acid, caused by a mixture of hydrogen bonded aggregates, are decomposed via time and frequency resolved CARS in the specific structural contributions.

Reversible hydrogen-bonded polymerization regulated by allosteric metal templation

2020 ◽  
Vol 56 (92) ◽  
pp. 14385-14388
Author(s):  
Tangxin Xiao ◽  
Weiwei Zhong ◽  
Weiwei Yang ◽  
Lijie Qi ◽  
Yan Gao ◽  
...  
Keyword(s):  
Cyclic Dimer ◽  
Supramolecular Polymer ◽  
Reversible Transformation ◽  
Self Assembled ◽  
Hydrogen Bonded

A stable quadruple hydrogen bonded cyclic dimer assisted by metal templation was successfully self-assembled and its reversible transformation to supramolecular polymer was investigated.

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