A new tripodal anion receptor with CH···X− hydrogen bonding

Ionic Liquids in Green Carbonate Synthesis

“…On combining this result with those of reaction runs using several types of amino alcohols, the reaction mechanisms for the oxazoilidionone and the substituted imidazolidione were proposed. In these mechanisms, IL was considered to be Lewis acid on the basis of reported IR and NMR studies, which showed the Lewis acidic nature of the hydrogen atom on the C(2) of the imidazolium ring [111,112]. Deng's group who carried out the reaction of CO 2 and propargylic alcohol (see section 2.1.1.)…”

A Metal‐Based Trisimidazolium Cage That Provides Six CH Hydrogen‐Bond‐Donor Fragments and Includes Anions

“…[13] This work has demonstrated that the CÀH c fragment of the imidazolium subunit is a powerful hydrogen-bond donor toward anions, even in aqueous media. It has also shown that the combination of a 1,3,5-trialkylbenzene platform and an {Fe II (bpy) 3 } 2+ subunit generates a versatile cavity for anion encapsulation. In particular, the coordination of the bpy nitrogen atoms to the d 6 metal center activates the proximate CÀH g fragments, which contribute to the unprecedented coordination of an anion by six CÀH groups.…”

“…[2] In the first example, 1, three imidazolium fragments are appended to a 1,3,5-trialkylbenzene platform. [3] The formation of stable 1:1 complexes of 1 with halides in MeCN was ascertained through 1 H NMR spectroscopic titration experiments. Of the various tripodal receptors that have since been reported, the highest anion affinity was observed for 2, in which the hydrogen-bond-donating abilities of the CÀ H fragments are enhanced by the proximate NO 2 substituent on each imidazolium ring.…”

“…First, we appended a 2,2'-bipyridine (bpy) subunit to each imidazolium fragment of the tripod to give 3-(PF 6 ) 3 . Then, the 3-(PF 6 ) 3 Nonlinear least-squares treatment of the titration data, using dedicated software, [7] indicated the formation of an [Fe À ion is included within the trisimidazolium cavity and participates in three hydrogen bonds with the CÀH c fragments from each of the imidazolium subunits (H c = H10, H27, H44; average H c ···Br 2.714(10) ) and three hydrogen bonds with the C À H g fragments of the nearest pyridine rings (H g = H21, H38, H55; average H g ···Br 3.063(10) ). Thus, the coordination of the anion by the C À H g fragments, which was preliminarily inferred from the 1 H NMR spectroscopic titration, has been demonstrated by X-ray diffraction.…”

Microwave-assisted synthesis of novel amide based chiral tripodal receptors for recognition of cation and anion sensors

“…Molecular design allows controlling binding properties such as selectivity, stability and complexation. Selectivity of a tripodal receptor largely depends on cavity size and rigidity of the arms [15][16][17] and therefore, they are known to have several advantages compared to monopodal and bipodal receptors: i) they usually bind metal ions very strongly due to increasing chelating influence, ii) bulkiness of tripodal ligands allows them to be more reactive towards metal ions. Because of the distinctive features of synthetic tripodal receptor system, their design and development is a very active field of study in the supramolecular chemistry.…”