Work

A Competing Hydrogen Bond Network Offers Access to a New Conformation in 24-Atom Triazine Macrocycles

Year: 2025

Type: article

Abstract: For a family of 24-atom triazine macrocycles, a single intramolecular hydrogen bond (IMHB) network leads to a conserved, hinge-like motif in solution. Modifications to the backbone of these macrocycles preserve this motif. Modifications to peripheral sites lead to conformational isomers due to hindered bond rotation while conserving the hinge motif. Here, a competitive IMHB network is introduced by the addition of a hydrogen bond donor on the periphery. Cyclization remains quantitative, but multiple conformers result. Three conformers are derived from the hinge motif. Three others are attributed to a new motif that utilizes the new IMHB network. Crystallographic analysis confirms this hypothesis and establishes that this new motif differs significantly from the original with respect to overall shape and disposition of groups. Variable temperature 1H NMR spectroscopy is used to partially assign the spectra because conformers adopting the hinge motif undergo dynamic motion on the NMR timescale, while the new motif appears static. QTAIM analysis corroborates the hydrogen bond designations in the new conformer and categorizes these interactions as moderate and strong.

Source: Molecules

DOI: 10.3390/molecules30224475

Authors: K. Harsha Vardan Reddy, Arshad Mehmood, Akop Yepremyan, Eric E. Simanek

Institutions: Texas Christian University, Stony Brook University

Language: English

Topic: Supramolecular Chemistry and Complexes

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,258

Funders: Welch Foundation, National Institutes of Health, National Institute of General Medical Sciences