Induction, Resonance, and Secondary Electrostatic Interaction on Hydrogen Bonding in the Association of Amides and Imides

Abstract

Both computations and experiments have confirmed that amides have stronger self-associations than imides. While this intriguing phenomenon is usually explained in the term of secondary electrostatic repulsion from the additional spectator carbonyl groups in imides, recently it was proposed that the π resonance effect from the spectator carbonyl which alters the balance between the acidity of the hydrogen-bond (H-bond) donor and the basicity of the H-bond acceptor is the major cause. In this work, we examined the roles of π resonance and the secondary electrostatic interaction in the formation of amide and imide dimers by deactivating the π conjugation from the spectator carbonyl and flipping the spectator carbonyl using the block-localized wave function method which is the simplest variant of valence bond theory. Energetic, geometrical, and spectral results show that three major forces, namely the σ induction effect (IE), π resonance effect (RE), and secondary electrostatic interaction (SEI), contribute to the different binding energies in the dimers of amides and imides. Whereas IE favors stronger binding among imides, both RE and SEI diminish the self-association of imides. Obviously, the negative force from RE and SEI exceeds the positive force from IE. Relatively, SEI plays a little bigger role than RE.

Acylsemicarbazide Moieties with Dynamic Reversibility and Multiple Hydrogen Bonding for Transparent, High Modulus, and Malleable Polymers

“…To evaluate the relative distribution, energies, and structures of H-bonded aggregates, we investigated a wide range of aggregates for model molecule 8 (Figure A; R′ = H), which has a similar structure to the ASC units in the PASC materials, by B97D/6-311G++(2d,2p) density functional calculations. , Six N–H···OC hydrogen bonds can be formed between two monomers toward an H-bonding aggregate . With extra ASC moieties every time another six H-bonds can be formed, to yield extended H-bonded aggregates, and a rather constant energy gain of 125 (± 10) kJ·mol –1 per extra unit was obtained (Figure B).…”

“…31,32 Six N−H•••OC hydrogen bonds can be formed between two monomers toward an H-bonding aggregate. 33 With extra ASC moieties every time another six H-bonds can be formed, to yield extended H-bonded aggregates, and a rather constant energy gain of 125 (± 10) kJ•mol −1 per extra unit was obtained (Figure 3B). This value of 125 kJ•mol −1 is comparable to the dimerization energy (160 kJ•mol −1 ) for 2-ureido-4[1H]pyrimidinone (UPy) at the same level of theory.…”

Resonance-Assisted Hydrogen Bond—Revisiting the Original Concept in the Context of Its Criticism in the Literature

“…There were also many in which this idea was followed. See, for some recent examples, [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ], and references therein.…”

聚合物中螺吡喃原位“自笼”及光响应调控

“…酰胺键之间的氢键增加了聚合物链的刚性 [30][31][32][33] , MC 之间的有序堆叠 [33] , 以及 MC 和酯−酰胺结构片段之 间的偶极-偶极相互作用 [15,17,[33][34] 进一步加强了抑制 MC 运动的效应. 我们把这种 MC 催化交联锁定自身 结构的策略称为 MC 的"自笼"化.…”