The Two Faces of Hydrogen‐Bond Strength on Triple AAA–DDD Arrays

Abstract

Systems that are connected through multiple hydrogen bonds are the cornerstone of molecular recognition processes in biology, and they are increasingly being employed in supramolecular chemistry, specifically in molecular self-assembly processes. For this reason, the effects of different substituents (NO2, CN, F, Cl, Br, OCH3 and NH2) on the electronic structure, and consequently on the magnitude of hydrogen bonds in triple AAA-DDD arrays (A=acceptor, D=donor) were evaluated in the light of topological [electron localization function (ELF) and quantum theory of atoms in molecules (QTAIM)], energetic [Su-Li energy-decomposition analysis (EDA) and natural bond orbital analysis (NBO)], and geometrical analysis. The results based on local H-bond descriptors (geometries, QTAIM, ELF, and NBO) indicate that substitutions with electron-withdrawing groups on the AAA module tend to strengthen, whereas electron-donating substituents tend to weaken the covalent character of the AAA-DDD intermolecular H-bonds, and also indicate that the magnitude of the effect is dependent on the position of substitution. In contrast, Su-Li EDA results show an opposite behavior when compared to local H-bond descriptors, indicating that electron-donating substituents tend to increase the magnitude of H-bonds in AAA-DDD arrays, and thus suggesting that the use of local H-bond descriptors describes the nature of H bonds only partially, not providing enough insight about the strength of such H bonds.

A σ-hole interaction with radical species as electron donors: does single-electron tetrel bonding exist?

“…According to the fact that electron-withdrawing groups in the proton donor can strengthen hydrogen bonds, 57 it is interesting to reveal the influence of the substituents on the interaction strength of the single-electron tetrel bond. According to the fact that electron-withdrawing groups in the proton donor can strengthen hydrogen bonds, 57 it is interesting to reveal the influence of the substituents on the interaction strength of the single-electron tetrel bond.…”

Study of Anti-Tuberculosis Activity Behaviour of Natural Kaurane and Trachylobane Diterpenes Compared with Structural Properties Obtained by Theoretical Calculations

“…The vibrational frequency calculations were carried out using the Gaussian 09 program [42] employing the BP86/TZP [43] model. The lipophilicity of the studied compounds was calculated with use of the COSMO-RS (Conductor-like Screening Model for Real Solvents) [44][45][46] methodology, which is implemented in the ADF (Amsterdam Density Functional) package [47][48][49][50].…”

Advances in bonding and properties of inorganic systems from relativistic calculations in Latin America

“…In addition, several host‐guest studies of lighter elements have been carried out involving the ExBox 4+ , Ex 2 Box 4+ , and CBPQT 4+ by Nagurniak and Ulloa, and the noncovalent character of hydrogen‐bond strength on triple AAA‐DDD arrays, has also been accounted for. On the other hand, Claveria‐Cádiz has proposed a series of Keggin heteropolyanions containing fifth period main group heteroatoms, [XM 12 O 40 ] n ‐ (X = Sn(IV), Sb(V) and Te(VI); M = Mo and W; n = 2,3,4), where a detailed energy decomposition analysis of the {XO 4 }‐{M 12 O 36 } interaction shows the existence of a predominant ionic character …”