A DFT Study of Tin‐ and Crown‐Ether‐Based Host Molecules Capable of Binding Anions and Cations Simultaneously

Abstract

DFT calculations are reported for a series of tin‐ and crown‐ether‐based host compounds {i.e., the trimethyl derivatives [18]‐crown‐6‐C6H3COOSn(CH3)3 and [15]‐crown‐5‐C6H3COOSn(CH3)3} capable of binding cations and anions simultaneously. The B3LYP functional together with the 6‐31G* basis set was used for the atoms C, H, N, O, S, Na and K and the 3‐21G* basis set for Sn in order to obtain insights into the factors determining the nature of the interactions of these compounds with the neutral molecules acetone and H2O, the SCN− anion, and the Na+ and K+ cations. The interaction strength pattern with these molecules was explained by the use of a series of reactivity descriptors such as the Fukui function, hardness, local softness, and the MEP (molecular electrostatic potential). In all cases studied in this paper, the complexes with Na+ were more stable than those with K+, correlating with the size of the cation and the volume available in the crown ether. Moreover, this finding is also in accordance with the greater hardness of Na+ relative to K+, in combination with the hard environment of the crown ether moiety. This region was also analysed by computation of electrostatic potentials, which showed that highly negative values are associated with the inside region of the cavity of the crown, this region thus being amenable to electrophilic attack. The HSAB principle, characterising the reactive sites on the basis of local softness and the Fukui function, provided a firm explanation of the reactivity of the tin atom of the crown ether benzocarboxylate towards SCN−, acetone and water. The HSAB concept was also successfully used to explain the preference of the tin atoms in both crown ethers to bind with the nitrogen atom rather than the sulfur atom of SCN−. This result is a confirmation that the tin atoms in the compounds under consideration behave as hard atoms. Overall, these results fit remarkably well with previous experimentally measured NMR spectroscopy data and demonstrate that the interactions of this kind of molecules can be predicted and interpreted by the use of DFT calculations and DFT‐based reactivity descriptors, as well as MEP calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Deciphering Noncovalent Interactions Accompanying 7,7,8,8‐Tetracyanoquinodimethane Encapsulation within Biphene[n]arenes: Nucleus‐Independent Chemical Shifts Approach

“…Recently, Jiang and co-workers synthesized oxatub [4]arenes based on naphthalene monomers. [22] Stoddart et al derived new macrocycles from fused aromatic ring or heteroatoms composed of 1,4-phenylene-bridged bipyridinium linkages to form a box-like architecture or ExBox 4 + , which was explored as a scavenger for an array of polycyclic aromatic hydrocarbons in aqueous or organic media.…”

“…[27] EtBP [n] hosts are shown schematically in Figure 1. Two cyclic oligomers with three or four biphenol diethyl ether units, namely, 1) a distorted triangular-prismatic ethylated biphen [3]arene (EtBP [3]), and 2) a partial chair-like ethylated biphen [4]arene (EtBP [4]), structures have been obtained. The condensation of repeating 4,4'-biphenol or 4,4'-biphenol ether units through methylene bridges at 3-and 3'-positions render biphen[n]arene macrocycles with different physicochemical behavior than those based on monobenzene/heterocyclic units.…”

“…Design and synthesis of novel macrocycle receptors, such as crown ethers, [1] cyclodextrins [2] cucurbiturils, [3] or their derivatives, [4][5][6] have been of growing interest in supramolecular chemistry. Such molecular containers are endowed with a large affinity and high selectivity toward cationic [7,8] or neutral guests [9] and find potential applications in drug delivery, [10] extraction and separation, [11] stimuli-responsive materials, [12] and other diversifying areas.…”

Scale Alpha and Beta of Quantitative Convergence and Chemical Reactivity Analysis in Dual Cholinesterase/Monoamine Oxidase Inhibitors for the Alzheimer Disease Treatment Using Density Functional Theory (DFT)

“…For instance, electronic chemical potential ( ), electrophilicity ( ), hardness ( ), electronegativity ( ), and softness ( ) are examples of such reactivity descriptors [26][27][28][29][30]. These reactivity indexes are used commonly to understand chemical reactivity and molecular selectivity [31][32][33][34]. These descriptors are supported on DFT [26][27][28][29][30].…”

“…The local property developed in this work is the Fukui Function (FF). FF typically is a function that describes the local role of a specific atom within a molecule [31][32][33][34]. We also propose and seek a correlation and complementarity of reactivity descriptors with QS.…”