Aspects of Anion Coordination from Historical Perspectives

Steric influence of adamantane substitution in tris-urea receptor: encapsulation of sulphate and fluoride-water cluster

“…Solvents used for synthesis and crystallization were purchased from Merck, India and used as supplied. 1 H NMR spectra were recorded on a Varian FT-400 MHz instrument and chemical shifts were recorded in parts per million (ppm) on a scale using tetramethylsilane [Si(CH 3 ) 4 ] or a residual solvent peak as a reference. 13 C spectra were obtained at 100 MHz.…”

“…In supramolecular chemistry, the encapsulation and recognition of anions within the self-assemblies of host molecules is an area of immense research interest due to the essential biological roles of anions [1][2][3][4][5][6] and also because of their influence in clinical, environmental and industrial purposes. 7 Understanding of hydrated-anions is a highly appreciated area of research due to their structures, energetics and activities in hydrated state.…”

Structure, synthesis and biological properties of the pentacyclic guanidinium alkaloids

“…Electronically, the positively-charged guanidine moiety is known for its ability to engage in anion binding. 6,51 Together, these properties make this core a promising candidate as an anion host molecule (Fig. 4, left).…”

“…Because of the basicity of guanidine (p K a = 13.6), its conjugate acid, guanidinium cation ( 3 ), binds with anionic substrates such as carboxylates or phosphates. 6 Marine natural products containing the guanidine functionality exhibit a broad spectrum of biological activities, attributed to the multiple ways that the guanidinium cation engages in non-covalent interactions. 7 …”

Macrocycle Synthesis by Chloride-Templated Amide Bond Formation

“…The central role of anions in environmental science, biology, and medicine has motivated chemists to develop selective anion receptors. Many of these receptors are macrocycles as long as the high level of favorable preorganization allows achieving an improved selectivity and stronger interactions. − The synthesis of macrocyclic compounds is challenging and usually requires an important synthetic effort in the final macrocyclization step, which is in many instances the yield limiting step . In this regard, the use of anions as templates is a promising synthetic methodology to achieve efficient macrocyclization processes; however, this approach has not been fully explored in many of these processes. − …”