Open-chain polyethers. Influence of aromatic donor end groups on thermodynamics and kinetics of alkali metal ion complex formation

Tuemmler, Burkhard; Maaß, G.; Voegtle, F.; Sieger, Heinz; Heimann, Ulrich; Weber, Edwin

doi:10.1021/ja00504a014

Cited by 149 publications

(46 citation statements)

References 3 publications

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“…It is apparent from a consideration of the data in Table 2 that the most important characteristic of the acyclic polyethers is the length of the chain and not the nature of the terminal "caps" (12), (see Fig. 2).…”

Section: Resultsmentioning

confidence: 99%

The solubilization of potassium permanganate by polyethylene glycols

Lee¹,

Karaman²

1982

Can. J. Chem.

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. Can. J . Chem. 60, 2456 (1982). The abilities of various cyclic and acyclic polyethers to solubilize potassium permanganate in organic solvents have been compared. In general, the cyclic compounds (crown ethers) are more effective than acyclic polyethers of comparable molecular weights. Each mole of 18-crown-6 is capable of solubilizing one mole of potassium permanganate in most solvents whereas the corresponding linear polymer, dimethyloctaethylene glycol, is much less effective, particularly in solvents of low polarity. Very long chain polymers are capable of complexing more than one mole of potassium ion per mole of polyether and thus bringing more than one mole of potassium permanganate into solution. A comparison with other studies on acyclic polyethylene glycols suggests that these structures would be helical with the oxygen complexed potassium ions inside and the permanganate anions arranged along the exterior.

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Section: Resultsmentioning

confidence: 99%

The solubilization of potassium permanganate by polyethylene glycols

Lee¹,

Karaman²

1982

Can. J. Chem.

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“…The title compound was prepared from 1,4-bis(bromomethyl)benzene and 8-hydroxyquinoline by a literature procedure (Tummler et al, 1979). Crystals suitable for X-ray analysis were formed by slow evaporation of a solution of the ligand in CH 2 Cl 2 /MeOH solution.…”

Section: Methodsmentioning

confidence: 99%

1,4-Bis(8-quinolyloxymethyl)benzene

Steel

Al-Mandhary

2004

Acta Cryst E

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The two quinoline rings of the title compound are differently inclined to the plane of the central benzene ring. The intermolecular packing involves C-H···N and π-π stacking interactions. CommentWe have recently embarked on a study of a diverse series of bridging heterocyclic ligands that comprise 8-quinolyloxy units separated by various spacer groups (Al-Mandhary & Steel, 2002). As part of this work we prepared all three isomers of the ligands with xylylene spacers and showed that both the ortho-and meta-isomers readily formed transition metal complexes with interesting molecular structures (Al-Mandhary & Steel, 2004a). In contrast, the para isomer, 1,4-Bis(8-quinolyloxymethyl)benzene (1), proved singularly resistant to the formation and isolation of any metal complexes. This raised some doubt as to the integrity of the ligand itself and, thus, a single-crystal X-ray structure determination of 1 was carried out, the results of which are reported herein.The structure crystallizes in the monoclinic space group P2 1 /n with a full molecule in the asymmetric unit. The potential for higher crystallographic symmetry is precluded by the very different orientations of the two quinolyloxymethyl substituents; the mean-planes of the two quinoline rings are inclined to the plane of the central aromatic ring at angles of 47.3 (2) and 106.8 (2)°, respectively. Also, the oxygen atoms are differently displaced from the plane of the central ring, as reflected in the torsional angles C2-C1-C11-O1 = 143.5 (2) and C3-C4-C21-O2 = 109.0 (2)°. Similar variations were observed in the structure of a durene-derived tetrasubstituted analogue (Al-Mandhary & Steel, 2004b). The reason for these differences most probably (Desiraju, 2002) lies in the crystal packing interactions, which contain weak C-H···N (Amoore et al., 2003) and π-π stacking interactions (Hunter et al., 2001;Jennings et al., 2001;Meyer et al., 2003). Specifically, adjacent molecules are weakly linked by C-H···N interactions between the quinoline rings, as defined by the following intermolecular contacts: N11-H24 = 2.42 (3) Å and N21-H14 = 2.59 (3) Å. The strongest π-π interactions are between the central aromatic rings of adjacent molecules, whose mean-planes and centroids are separated by approximately 3.49 Å and 3.79 Å, respectively. ExperimentalThe title compound was prepared from 1,4-bis(bromomethyl)benzene and 8-hydroxyquinoline by a literature procedure (Tummler et al., 1979). Crystals suitable for X-ray analysis were formed by slow evaporation of a solution of the ligand in CH 2 Cl 2 /MeOH solution.

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“…[15,16] We also prepared the corresponding para-isomer, [16] but were unable to form any crystalline complexes from it. Related podands, including 3, have previously been…”

Section: Introductionmentioning

confidence: 99%