“…A variety of heteroconjugated RAHB systems was studied with the aim of determining crystal engineering rules for the production of materials with potential practical applications . The most well‐established cases of RAHB (Scheme ) include intramolecular H‐bonds in β‐diketones ( I ), β‐enaminones ( II ), Schiff bases ( III ), β‐enaminoimines ( IV ), hydrazones ( V and VI ), formazans ( VII ), 1,3,5‐triazapentadienes ( VIII ), ortho ‐substituted aromatic compounds ( IX – XII ), oximes ( XIII – XVI ), mercaptans (or thiols) ( XVII – XIX ), thioketones ( XX – XXII ), selenones or tellurones ( XXIII and XXIV ), and 8‐ or 10‐membered RAHB system containing compounds ( XXV and XXVI ) . These RAHB moieties are ubiquitous in various fields, including organic and inorganic synthesis, crystal growth and design, supramolecular chemistry, medicinal chemistry, and materials chemistry, and have been used in the activation of covalent bonds, crystal engineering, dynamic combinatorial chemistry, molecular recognition, E / Z isomeric resolution, racemization/epimerization of amino acids, solvatochromism, and liquid‐crystalline materials, among other applications.…”