Carbonyl–carbonyl interactions and amide π-stacking as the directing motifs of the supramolecular assembly of ethylN-(2-acetylphenyl)oxalamate in a synperiplanar conformation

Abstract

The title compound, C12H13NO4, is one of the few examples that exhibits a syn conformation between the amide and ester carbonyl groups of the oxalyl group. This conformation allows the engagement of the amide H atom in an intramolecular three-centred hydrogen-bonding S(6)S(5) motif. The compound is self-assembled by C=O...C=O and amide-π interactions into stacked columns along the b-axis direction. The concurrence of both interactions seems to be responsible for stabilizing the observed syn conformation between the carbonyl groups. The second dimension, along the a-axis direction, is developed by soft C-H...O hydrogen bonding. Density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) level of theory were performed to support the experimental findings.

Microcrystalline solid–solid transformations of conformationally-responsive solvates, desolvates and a salt of N,N′-(1,4-phenylene)dioxalamic acid: the energetics of hydrogen bonding and n/π → π* interactions

“…Finally, the whole assembly is achieved through face-to-face stacking interactions (π → π*) between the aromatic rings ( Cg1 = C1–C6, Cg2 = C21–C23) and the amide groups ( Cg4 = N7–C8, Cg3 = N27–C28) ( Cg1 ⋯ Cg4 = 3.403(4) Å, Cg1 Perp = 3.378(4) Å; Cg2 ⋯ Cg3 = 3.475(4) Å, Cg2 Perp = 3.471(4) Å). 42 This kind of interaction has already been found to contribute to the supramolecular architecture of oxalamates 43 and proteins. 44 The n/π → π* interactions develop the 3D along the direction of the c axis [5 −8 0].…”

Synthesis, Optical Characterization in Solution and Solid-State, and DFT Calculations of 3-Acetyl and 3-(1′-(2′-Phenylhydrazono)ethyl)-coumarin-(7)-substituted Derivatives

“…On the contrary, an aggregation-caused quenching (ACQ) effect is observed on 1b. In the crystal lattice, the molecules of 1b are arranged in dimers through antiparallel type carbonyl-carbonyl interactions [51] at Cg (Bz)-Cg (L) distance of 6.38 Å and the amino-ethyl groups pointing to opposite directions [49]. The free rotation of the pendant -NEt 2 and 3-Ac groups in 1b is restricted as in 1d, but with the contrary effect.…”

Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N′-1,4-Phenylenedioxalamic Acid (1:2) Salt: The Role of Hydrogen Bonding and n→π * Charge Assisted Interactions

“…Theoretical studies and experimental work [ 16 ] have demonstrated the high flexibility of the oxalic acid derivatives. Both oxalyl carbonyls are usually in anti disposition [ 17 ], but they less frequently adopt the syn disposition, induced by steric constraints [ 18 , 19 ] or by coordination with metals in the form of carboxylates [ 14 ].…”