A Halogen‐Bonded Dimeric Resorcinarene Capsule

Abstract

Iodine (I 2 )a cts as ab ifunctional halogen-bond donor connecting two macrocyclic molecules of the bowlshaped halogen-bond acceptor,N -cyclohexyl ammonium resorcinarene chloride 1,t of orm the dimeric capsule [(1,4-dioxane) 3 @1 2 (I 2 ) 2 ]. The dimeric capsule is constructed solely through halogen bonds and has as ingle cavity (V = 511 3 )l arge enough to encapsulate three 1,4-dioxane guest molecules.Hydrogen bonds (HB) are weak interactions that are extensively used in the design of organic supramolecular assemblies. [1] Their application spans from the preparation of simple compounds to complex materials and those mimicking biological processes. [2] Thehalogen bond (XB) is analogous to HB in strength and directionality,a nd has recently been defined. [3] This noncovalent interaction is based on apolarized halogen atom which interacts with aLewis base,insome cases with coordinative [4] or covalent character,toform aXB. [3] The XB donors exhibit an anisotropic electron distribution leading to an electropositive region on the halogen atom named the s hole. [5] Thes trength of the XB interactions (R À X···A) usually follow the trend X = I > Br @ Cl @ F. Dihalogens (X 2 ) are very interesting XB donors and often display very short XB distances,s ometimes approaching those of the corresponding covalent bonds. [6] Though the polarizability of the halogen in an XB donor is critical, the strength of the X 2 ···A-type XB can be correlated to the ability of Atoaccept ah alogen bond [7] as aL ewis base [8] leading to a" basicity scale" for I 2 ···A halogen bonds.Anions which are Lewis bases are good hydrogen-and halogen-bond acceptors. [7,9] Thea bility of anions to have multiple coordination geometries has led to their utilization in numerous noncovalent interactions. [10] Halides are spherical, symmetrical anions with the negative charge concentrated on as ingle atom making them excellent HB and XB acceptors. [9,10] As ar esult of these properties [11] halides have coordination numbers,t hat is,t he number of hydrogen or halogen bonds,r anging typically from four to eight. If simultaneously present, both HB and XB can therefore be used in tandem to form functional assemblies. [12] Multiple 1D,[*] Dr.

Comparison of CH···O, SH···O, Chalcogen, and Tetrel Bonds Formed by Neutral and Cationic Sulfur-Containing Compounds

“…Even a strongly electronegative halogen atom can interact attractively with an electron donor [35][36][37][38][39][40][41][42][43][44][45][46][47] . This attraction is facilitated by an anisotropic distribution of charge around the halogen (X) atom within a R-X bond.…”

Hydrogen‐ and Halogen‐Bonds between Ions of like Charges: Are They Anti‐Electrostatic in Nature?

“…This X-bonding Cl -ÁÁÁI 2 ÁÁÁClhas also been utilized subsequently in a supermolecular assembly. [59] In spite of the electric neutrality of I 2 molecule, the pinning Clanions on each side suggest a repulsive electrostatic interaction and a potential "AE" feature. Most recently, the stability and characteristics of AEXB were studied computationally by Wang et al and Quiñonero et al [60,61] Obviously, a comparative study of the existence of "AE" in X-and H-bonds would be relevant to experimental cases.…”

“…Similarly, Martí‐Rujas et al made the tetrahalide anion [I 2 Cl 2 ] 2– , and found it to be a linear complex, Cl – ···I 2 ···Cl – , involving X‐bonds between a central I 2 molecule and two Cl – anions. This X‐bonding Cl – ···I 2 ···Cl – has also been utilized subsequently in a supermolecular assembly . In spite of the electric neutrality of I 2 molecule, the pinning Cl – anions on each side suggest a repulsive electrostatic interaction and a potential “AE” feature.…”

Substituent Effects on the Binding of Halides by Neutral and Dicationic Bis(triazolium) Receptors

“…For example, highly asymmetric distribution of electron density around electronegative atoms of the chalcogen and pnicogen families allows a means for them to interact attractively with the negatively charged region of a partner [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] . The halogen atoms are no exception to this behavior and the rapidly developing exploration 19,[24][25][26][27][28][29][30] of the eponymous halogen bonds (XBs) has found application in numerous areas of chemistry, such as molecular recognition [31][32][33] , organocatalysis [34][35][36][37] , and crystal engineering [37][38][39][40][41][42][43] .…”