Impact of Covalent Modifications on the Hydrogen Bond Strengths in Diaminotriazine Supramolecules

Abstract

Melamine (M) is a popular triamine triazine compound in the field of supramolecular materials. In this work, we have computationally investigated how substituents can be exploited to improve the binding strength of M supramolecules. Two types of covalent modifications were studied: the substitution of an H atom within an amine group −NHR, and the replacement of the whole −NH2 group (R=H, F, CH3 and COCH3). Through our dispersion‐corrected density functional theory computations, we explain which covalent modification will show the best self‐assembling capabilities, and why the binding energy is enhanced. Our charge density and molecular orbital analyses indicate that the best substituents are those that generate a charge accumulation on the endocyclic N atom, providing an improvement of the electrostatic attraction. At the same time the substituent assists the main N−H⋅⋅⋅N hydrogen bonds by interacting with the amino group of the other monomer. We also show how the selected group notably boosts the strength of hexameric rosettes. This research, therefore, provides molecular tools for the rational design of emerging materials based on uneven hydrogen‐bonded arrangements.

Augmentation of inductive effects through short range intramolecular hydrogen bonds for the improvement of cooperativity of trimeric rosettes

“…The empirical dispersion correction was implemented with the 3/124=40 IOp keyword. This functional has exhibited a great performance in similar hydrogen-bonded systems 11 c , d ,12 and in good accordance with experiments. 22 The electronic wave function was obtained with contracted Gaussian-type orbitals 23 augmented with diffuse 24 and d and p polarization functions 25 by using the split valence 6-311++G(d,p) basis set.…”

“…9 We have demonstrated what the source of stability is in different tetrameric 10 and hexameric cyclic structures 11 and how to improve it. 12 Recently, it has been shown from experiments 13 and theory 14 how the length of the monomer impacts the cooperativity of a tetrameric macrocycle. Nevertheless, the use of trimeric rosettes is less usual in the literature and there are no studies about their cooperativity effects.…”

Acidity of Isomorphic Substituted Zeolites with B, Al and Ga Revisited

“…All the topologies exhibit a highly directional hydrogen bond that can be seen as a blue disk (inset 1 in Figure 6). This hydrogen bond is supported by other interactions such as a second and weaker hydrogen bond (inset 2 in Figure 6), [37] and a pnictogen bond between O and N atoms (inset 3 in Figure 6). In terms of the sigma hole concept, this pnictogen bond can be understood as an electrostatic interaction between the positive region of N (see maxima values of its electrostatic surface in Figure S6) and the negative region of O associated to its lone pair.…”