Selective Nitrate Recognition by a Halogen‐Bonding Four‐Station [3]Rotaxane Molecular Shuttle

Abstract

The synthesis of the first halogen bonding [3]rotaxane host system containing abis-iodo triazolium-bis-naphthalene diimide four station axle component is reported. Proton NMR anion binding titration experiments revealed the halogen bonding rotaxane is selective for nitrate over the more basic acetate,hydrogen carbonate and dihydrogen phosphate oxoanions and chloride,and exhibits enhanced recognition of anions relative to ah ydrogen bonding analogue.T his elaborate interlocked anion receptor functions via an ovel dynamic pincer mechanism where upon nitrate anion binding,b oth macrocycles shuttle from the naphthalene diimide stations at the periphery of the axle to the central halogen bonding iodotriazolium station anion recognition sites to form aunique 1:1 stoichiometric nitrate anion-rotaxane sandwich complex. Molecular dynamics simulations carried out on the nitrate and chloride halogen bonding [3]rotaxane complexes corroborate the 1 HNMR anion binding results.The prevalence of negatively charged species in biology and in the environment has deemed the development of synthetic anion receptors capable of their strong and selective recognition an important field of chemical research. [1][2][3] Thenitrate anion in particular is an environmental pollutant when leeched into lakes and rivers resulting from anthropogenic overuse of fertilizers or by acid rain.[4] Medically,a no ver exposure to nitrate via contaminated drinking water is associated with the formation of carcinogenic nitrosamines and ar ange of diseases such as methemoglobinemia (blue baby syndrome) in infants. [5] Thedesign of synthetic receptors capable of the selective recognition of nitrate is ac hallenge because of the anions inherent low affinity for hydrogen bonds and high energy of solvation.[6] To date only arelatively small number of nitrateselective tripodal acyclic,m acrocyclic and cage-like host systems have been reported that utilise convergent hydrogen bonding (HB) and/or anion-p interactions to recognise the oxoanion in polar organic solvents. [7][8][9][10][11][12][13][14][15][16][17][18][19] Thec hallenge of developing synthetic receptors that can rival the anion recognition properties of biotic systems relies upon the arrangement of at hree-dimensional convergent array of numerous HB donor groups in an optimized geometry for recognition of the complementary guest. [20,21] To meet this challenge we have exploited anion-templation to construct interlocked host structures [22,23] whose unique threedimensional cavities encapsulate anionic guest species.While during the past two decades HB has been widely exploited in anion receptor design, halogen bonding (XB), [24][25][26][27] the attractive highly directional interaction between an electron-deficient halogen atom and aL ewis base,h as only recently begun to be utilised for anion recognition. Of the relatively few examples of XB anion receptors reported to date,i ti sn oteworthy that all display promising,a nd significantly contrasting, anion recognition behaviour when compared ...

Halogen Bonding in Solution: Anion Recognition, Templated Self‐Assembly, and Organocatalysis

“…Anion-inducedmolecular shuttling of two macrocyclic wheels between atriazolium axle motif and an aphthalene diimide moiety in aXB/HB-based [3]rotaxane. 31: K a values obtained by 1 HNMR titration in CDCl 3 /CD 3 OD (1:1) at 298 K. [76] Photos reprinted from Ref. [76] with permission.C opyright 2016 WILEY-VCH Verlag GmbH & Co.KGaA, Weinheim.…”

Cocrystal assembled by 1,4-diiodotetrafluorobenzene and phenothiazine based on C—I...π/N/S halogen bond and other assisting interactions

“…The XB strength ranging from 5 to 180 kJ mol À1 can be comparable to the well known hydrogen bond (HB) strength (Metrangolo et al, 2005). XB's advantages include opening avenues in crystal engineering (Zbačnik et al, 2016;Mavračić et al, 2016), materials chemistry (Meyer & Dubois, 2013;Berger et al, 2015), anion recognition (Brown & Beer, 2016;Barendt et al, 2016), separation science (Metrangolo et al, 2009;Yan et al, 2014;Aakerö y et al, 2015), biological systems (Parisini et al, 2011;Jentzsch et al, 2012;Scholfield et al, 2013;Vargas Jentzsch & Matile, 2013;Jiang et al, 2016), as well as synthetic chemistry (Bulfield & Huber, 2016) etc.…”

Halogen‐Bonded Assemblies of Arylene Imides and Diimides: Insight from Electronic, Structural, and Computational Studies

“…[8] In 2007, Zou and co-workers theoretically proved the biologically relevant Br•••O phosphate interaction betweena denine-5-bromouracil and organic phosphate ion. [9] Findingsb yD iederich et al [10] and Parish et al [11] demonstrated the biologicals ignificance of halogenb ondingi np roteins and DNA.Interestingly,Rissanen [4a] and Diederich et al [12] have independently demonstrated the construction of supramolecular cagesu sing halogen-bondingi nteractions. Recently,B eer et al demonstratedt he importance of halogen bonding in anion recognition by ac hiral [2]rotaxane.…”

“…Recently,B eer et al demonstratedt he importance of halogen bonding in anion recognition by ac hiral [2]rotaxane. [12] In addition, the presence of halogen atoms on the periphery of organic/inorganic synthonsh as attracted scientific studies to augment the construction of supramolecular self-assemblies. [13] More recently, Molina and co-workers reported the generation of interlocked supramolecular polymers assisted by halogen bonding.…”