Molecular Symmetry and the Design of Molecular Solids:  The Oxalamide Functionality as a Persistent Hydrogen Bonding Unit

Abstract

A symmetry analysis based upon the structure of simple molecules and their anticipated intermolecular interactions can lead to successful predictions of molecular packing and crystal symmetry. As a demonstration of these ideas an in-depth study of the oxalamide functionality as a persistent hydrogen bonding unit is presented. The synthesis and structural characterization of a series oxalamide dicarboxylic acids is presented and the structures compared with the analogous urea compounds. Both the urea and oxalamide dicarboxylic acids form designed two-dimensional hydrogen-bonded -networks with a significant degree of reliability. The urea designs are quite reliable when there is a molecular 2-fold axis, but competing hydrogen bond patterns are found when less symmetrical molecules are studied. The oxalamide design based on inversion centers is also quite reliable, with the designed layer structure found in most cases.

Chiral Bis(amino alcohol)oxalamide Gelators—Gelation Properties and Supramolecular Organization: Racemate versus Pure Enantiomer Gelation

“…[16] The intermolecular hydrogen bonds (N1ÀH1 ¥¥¥ O1 and N11ÀH11 ¥¥¥ O11) complete the infinite motif along b; this is described by the unitary graph-set descriptor C(4). The chain also includes patterns defined by the graph-set descriptors R Table 5) that connect the chains into a two-dimensional pattern, described by Fowler and Lauher [17] as the b-network. The complete b-pattern is described by the unitary graph-set N 1 C(4)S(5)S(5)C(4)C(11)C(11).…”

Rigid Urea and Self-Healing Thiourea Ethanolamine Monolayers

“…9,10 Thioureas on the other hand show a more complex behavior due to the reduced electronegativity of a sulfur atom compared to the smaller carbonyloxygen, the higher acidity of the NH protons in ureas compared to thioureas, 11 and the longer hydrogen bonds caused by the larger size of a sulfur atom and its more diffuse electron cloud. 12 Moreover, thioureas form different rotamers and the molecules arrange almost orthogonally to each other.…”

Oxalamides as a hydrogen bonding motif in thermoplastic elastomers

“…The oxalamide group as a hydrogen bonding motif has been utilized in various research areas, like crystal engineering [80][81][82][83][84] , protein engineering [85][86][87][88] , organic gelators [89][90][91][92] and materials science 93 . Oxalamides, diamides of oxalic acid, are self-complimentary hydrogen bonding molecules capable of donating and receiving two hydrogen bonds ( Figure 2.5) 80 .…”

“…Oxalamides, diamides of oxalic acid, are self-complimentary hydrogen bonding molecules capable of donating and receiving two hydrogen bonds ( Figure 2.5) 80 . The solid state structure of N,N'-dimethyl oxalamide (DMO) as determined from X-ray data shows that the molecule has a planar trans configuration 94 .…”

“…The oxalamide groups provide like-to-like hydrogen bonding in one direction with a characteristic repeat distance of ∼5Å, whereas the end groups dimerize in a second direction through hydrogen bonding 80,83,84 . By functionalizing diacetylenes with complementary endgroups, these monomers can be co-crystallized with the oxalamide host compounds (Figure 2.8b).…”