Architecture of new Concave Host Molecules

Vögtle, Fritz; Seel, Christian; Berscheid, R.; Gross, Jens; Windscheif, Paul M.

doi:10.1007/978-94-011-1058-7_21

Cited by 16 publications

(16 citation statements)

References 12 publications

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“…Host–guest chemistry involves the formation of molecular complexes composed of host molecules noncovalently bound to guest molecules in a unique structural relationship . Macrocyclic compounds such as cyclophanes are widely studied because of their great technological importance in industrial application. In particular, functionalized cyclophanes show the following characteristic properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Dabsyl-Appended Cyclophanes and Their Heterodimer Formation with Pyrene-Appended Cyclophanes

Hayashida

Kaku

2013

J. Org. Chem.

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As a quencher-type host, dabsyl-appended cyclophanes bearing positively and negatively charged side chains (1a and 1b, respectively) were synthesized. Formation of cyclophane heterodimers of 1a with anionic fluorescent cyclophane bearing a pyrene moiety 2b was confirmed by fluorescence titration experiments. The 1:1 binding constant (K) of 1a toward 2b was calculated to be 1.6 × 10(5) M(-1). On the other hand, almost no complexation affinity of 1a toward cationic analogue of fluorescent cyclophane 2a was confirmed by the identical methods, indicating that electrostatic interactions became effective in the formation of cyclophane heterodimers. In addition, van't Hoff analysis applied to the temperature-dependent K values for the heterodimer formation gave negative enthalpy (ΔH) and entropy changes (ΔS). The large and negative ΔH values as well as small and also negative ΔS values showed that the complexation is an exothermic and enthalpy-controlled but not entropy-driven process. A similar trend of molecular recognition was also confirmed for formation of cyclophane heterodimers of 1b with 2a by the identical methods.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Dabsyl-Appended Cyclophanes and Their Heterodimer Formation with Pyrene-Appended Cyclophanes

Hayashida

Kaku

2013

J. Org. Chem.

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“…Polycyclic aromatic hydrocarbons form complexes with metal ions such as Ag + . The bonding in these kinds of π -complexes is due to an electron transfer between the aromatic moiety and the positively charged metal cation. , Vögtle et al showed that concave hydrocarbons are able to extract certain metal cations from an aqueous solution. The complexation selectivity of the hydrocarbon cyclophanes allows applications such as incorporation in ion-selective electrodes.…”

Section: Introductionmentioning

confidence: 99%

An ab Initio MO Study of Silver Triflate Complexation in [2.2.1]Cyclophane π-Prismands

2002

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Ab initio Hartree−Fock and DFT MO calculations have been used to study the conformations of six [2.2.1]cyclophane π-prismands and the formation of their π-complexes with silver triflate (AgSO3CF3). The lowest energy cyclophane conformations and their silver triflate π-complexes have been calculated with HF/3-21G* and B3LYP/3-21G* levels of theory. The nature of bonding in silver triflate π-complexes has been studied with natural bond orbital analysis (NBO). Energies of the calculated cyclophanes and complexes, together with the formation energies of those complexes, have also been discussed. The results have been compared to available X-ray crystal structures and also to results of the previously published ab initio calculations of slightly larger [2.2.2]cyclophanes and their silver complexes. Calculated and experimental X-ray structures agreed reasonably well, given the rather small 3-21G* basis set. Changes in the bonding between the ligand and Ag+ ion were observed, due to an enhanced bonding of the triflate moiety over the silver atom ion in the calculated models. In these complexes the silver ion is bonded to the cyclophane cavity by the bonds formed by σ donation and d−π* back-donation between the silver ion and the hydrocarbon skeleton resulting in variable bonding modes from η 1 to η 6 per aromatic ring depending on the ligand conformation. In this case the σ donation from the hydrocarbon to the silver ion is the main contribution to the metal−cyclophane bonding. Bonding of the silver ion to the present π-prismands relates by strength to a single moderately strong hydrogen bond and varies between 25 and 50 kJ/mol. Due to the smaller cavity, the more rigid hydrocarbon skeleton, and the presence of the triflate moiety [2.2.1]cyclophanes form different types of interactions with silver ion when compared to previously published [2.2.2]cyclophane π-prismand complexes with Ag+ ion.

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“…Polycyclic aromatic hydrocarbons form complexes with metal ions such as Ag + . Bonding in these π-complexes is due to electron transfer between the aromatic moiety and the positively charged metal cation . Vögtle et al showed that concave hydrocarbons can extract certain metal cations from an aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio MO Study of Silver Ion Complexation in [2.2.2]Cyclophane π-Prismands

2000

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Ab initio Hartree-Fock and DFT MO calculations have been used to study the conformations of [2.2.2]cyclophane π-prismands and the formation of π-complexes with silver ion and [2.2.2]cyclophanes. The lowest energy cyclophane conformations have been calculated up to the HF/6-31+G* level of theory. The silver π-complexes of the lowest energy conformations have been calculated with HF/3-21G* and B3LYP/3-21G* levels of theory. The nature of bonding in silver ion π-complexes has been studied with natural bond orbital analysis (NBO). Energies of the calculated cyclophanes and complexes, together with formation energies of those complexes, have also been discussed. The results obtained have been compared to X-ray crystal structures whenever such structures were available. Calculated and experimental X-ray structures agreed reasonably well given provision to the rather small 3-21G* basis set and the omission of triflate anion in the calculation model. The NBO analysis showed that when Ag + is bonded to the cyclophane cavity, the bonds are formed by σ-donation and d-π*-back-donation between the silver ion and the hydrocarbon skeleton, resulting in hexahapto (3×η 2 ) overall π-bonding. This is in agreement with the well-known "bondingback-bonding" scheme in transition metal carbonyl complexes. In this case the σ-donation from hydrocarbon to silver ion is the main contribution to the metal-cyclophane bonding. One dihapto (η 2 ) bonding to one aromatic ring in the present π-prismands relates by strength to a single strong hydrogen bond, which is up to 100 kJ/mol; thus the strength of this 3×η 2 bonding in these [2.2.2]cyclophane π-prismands can be compared to three simultaneous strong hydrogen bonds.

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Architecture of new Concave Host Molecules

Cited by 16 publications

References 12 publications

Synthesis of Dabsyl-Appended Cyclophanes and Their Heterodimer Formation with Pyrene-Appended Cyclophanes

Synthesis of Dabsyl-Appended Cyclophanes and Their Heterodimer Formation with Pyrene-Appended Cyclophanes

An ab Initio MO Study of Silver Triflate Complexation in [2.2.1]Cyclophane π-Prismands

Ab Initio MO Study of Silver Ion Complexation in [2.2.2]Cyclophane π-Prismands

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