Theoretical study of free and encapsulated carboxylic acid and amide dimers. Issue 5 (29th March 2012)

• Record Type: Journal Article
• Authors: Tzeli, Demeter; Petsalakis, Ioannis D.; Theodorakopoulos, Giannoula; Ajami, Dariush; Rebek, Julius; Gidopoulos, Nikitas I.; Theophilou, Andreas K.
• Is Part Of: International journal of quantum chemistry. Volume 113:Issue 5(2013:Mar. 05)
• Page Start: 734
• Page End: 739
• Publication Date: 2012-03-29
• Subjects: Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.24062
• Languages: English
• ISSNs: 0020-7608

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The homodimers and heterodimers of four carboxylic acids RCOOH and four amides RCONH₂, where R = H, methyl, phenyl, <italic>p</italic>‐ethylphenylene have been calculated via DFT(M06‐2X), MP2, and CCSD(T) methods in conjunction with the 6‐31G(d, p), 6‐311+G(d, p), aug‐cc‐pVTZ, and aug‐cc‐pVQZ basis sets to find out how the substituent R influences their dimerization energy (Δ<italic>E</italic>) and their hydrogen bond length. The calculated Δ<italic>E</italic> values range from 14 to 17 kcal/mol for the different dimers in the gas phase, with the ordering carboxylic homodimers ≥ amide‐carboxylic dimers &gt; amide homodimers. The M06‐2X/6‐311+G(d, p) geometries and Δ<italic>E</italic> values are in very good agreement with the corresponding MP2/aug‐cc‐pVQZ and CCSD(T)/aug‐cc‐pVTZ values. Coencapsulation of the dimers was studied to examine its effect on the calculated bond lengths and strength of the hydrogen bonds at the M06‐2X/6‐31G(d, p) level of theory. The experimental and calculated % distributions of the encapsulated dimers, taking into account statistical factors are in good agreement. © 2012 Wiley Periodicals, Inc.</p> </abstract>