Heteroditopic receptors

Organotin-Substituted [13]-Crown-4 Ethers: Ditopic Receptors for Lithium and Cesium Halides

“…Compounds 11-14 are colorless (13,14) to yellow (11) and red (12) crystalline solids that are soluble in CH 2 Cl 2 , CHCl 3 , and CH 3 CN and partially (11, 14) in methanol but insoluble in diethyl ether. The molecular structures of compounds 11 and 12 are shown in Figures 5 and 6; selected bond distances and bond angles are listed in Tables 3 and 4.…”

“…The 13 C NMR spectrum of [15 3 LiSCN] showed that the resonances for the C i , C20, and C17/C19 (according to the numbering scheme shown in Scheme 6) carbon atoms are respectively 0.9, 6.2, and 3.8 ppm high-frequency shifted with respect to the corresponding chemical shifts of the parent compound 3. The ESI-MS spectrum in the positive mode of [ 39 Cesium fluoride, CsF, has a lower lattice energy (748 kJ/ mol) 56 than lithium fluoride, and sandwich complexes formed between [12]crown-4 and Cs þ are known. 57 Moreover, the fluoride anion is able to coordinate to two Lewis acidic tin atoms with formation of a Sn-F-Sn bridge.…”

“…Compounds that incorporate in their framework individual anion- and cation-binding sites continue to attract considerable attention in the field of supramolecular host−guest chemistry. − The so-called ditopic receptors are multifunctional ligands that complex both an anion and a cation as a contact ion pair or solvent- or spatially-separated ion pair. The growing interest in such compounds is stimulated by the shortcomings of ion-pairing effects involved in the recognition processes of simple anion or cation receptors.…”

Organotin Compounds Ph2XSnCH2-[19]-crown-6 (X = Ph, F, Cl, Br, I, SCN) and Ph2ISnCH2Sn(I)PhCH2-[19]-crown-6 as Ditopic Receptors for Potassium Salts

“…In recent years so-called ditopic complexation of anions and cations has become a well-established subdiscipline in supramolecular host−guest chemistry, and both concepts and achievements in this field have been thoroughly reviewed. − Most of the ditopic receptors reported to date are purely organic and employ hydrogen bonding for anion recognition and Lewis-basic binding sites such as oxygen atoms in crown ethers for cation recognition. On the other hand, there are only few examples of ditopic receptors that make use of the Lewis acidity of organoelement/organometallic moieties or metal cations for anion binding.…”

Coordination motifs in modern supramolecular chemistry

“…47, 48 and 54) represent a group of heteroditopic receptors [53], i.e. polyfunctional ligands capable of binding cations and anions simultaneously.…”