Conformational properties of the THYME polyethers. The bis-THYME cylinder: a three-dimensional analog of 18-crown-6

Walba, David M.; Richards, Rodney M.; Hermsmeier, Mark A.; Haltiwanger, R. C.

doi:10.1021/ja00257a029

Cited by 25 publications

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“…The distances of K(1)−Cl(2) and K(1)−Cl(3) are 3.402(3) and 3.355(2) Å, respectively. This type of interaction was reported in [K 2 (OH 2 )-(L)][Pt II Cl 3 (DMSO-S)] {L = bis[tetrakis(hydroxymethyl)ethylene] fused-crown ethers; 3.33(2) Å} 42 and K[Pt II Cl 3 (DMSO-S)] [3.224(6) Å]. 43 The interaction of K−Cl in 4 is weaker than those in [K 2 (OH 2 )(L)][Pt II Cl 3 (DMSO-S)] and K[Pt II Cl 3 -(DMSO-S)].…”

Section: ■ Results and Discussionsupporting

confidence: 66%

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Kato

Unoura²,

Takayanagi

et al. 2013

Inorg. Chem.

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Five metal complexes of 2-methylisothiazol-3(2H)-one (MIO), [Co(III)(NH3)5(MIO)](3+), [Ru(II)(NH3)5(MIO)](2+), [Ru(III)(NH3)5(MIO)](3+), [Pt(II)Cl3(MIO)](-), and trans-[U(VI)O2(NO3)2(MIO)2], were synthesized, and their structures were determined by single-crystal X-ray crystallography. MIO is an ambidentate ligand and coordinates to metal centers through its oxygen atom in the cobalt(III), ruthenium(III), and uranium(VI) complexes and through its sulfur atom in the ruthenium(II) and platinum(III) complexes. This result suggests that MIO shows preferential behavior on its donating atoms. We also studied the electron-donor abilities of the oxygen and sulfur atoms of MIO. Various physical measurements on the conjugate acid of MIO and the MIO complexes allowed us to determine an acid dissociation constant (pKa) and donor number (DN) for the oxygen atom of MIO and Lever's electrochemical parameter (EL) and a relative covalency parameter (kL) for the sulfur atom.

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Section: ■ Results and Discussionsupporting

confidence: 66%

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Kato

Unoura²,

Takayanagi

et al. 2013

Inorg. Chem.

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“…This statement was confirmed by several studies on thermotropic LCs based on nuclear magnetic resonance (NMR): here, the molecular biaxiality is neglected or estimated to be very low (less than 0.05). , However, particularly for chiral molecules forming the SmC* phase, the conformational properties are predicted to be crucial in determining the occurrence of the ferroelectric phase, and its subphases, as well as its typical properties: spontaneous polarization, helical pitch length, and molecular tilt. According to several theoretical works, − the transition to the SmC* phase is related to a conformational change. Several theoretical and experimental works suggest that, due to the particular packing typical of the SmC* phase, the most stable conformer in the ferroelectric phase is bent-like , which is more stable than the more elongated uniaxial ones.…”

Section: Introductionmentioning

confidence: 99%

Conformational Changes at Mesophase Transitions in a Ferroelectric Liquid Crystal by Comparative DFT Computational and ¹³C NMR Study

Marini

Domenici

2010

J. Phys. Chem. B

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In this work, we report a detailed investigation on both the conformational and the orientational ordering properties of a ferroelectric liquid crystal mesogen, namely, M10/**, through the combination of high resolution solid state (13)C NMR and density functional theory (DFT) computational methods. The trends of the observed (13)C chemical shift in the blue, cholesteric, and ferroelectric SmC* phases of M10/** were analyzed in terms of conformational changes occurring in the flexible parts of the molecule. In particular, we focused on the aliphatic alpha methylenoxy carbons because of their high sensitivity to mesophase environment, as evidenced by experimental (13)C chemical shift anisotropy (CSA). DFT computation of the chemical shift tensors as a function of geometrical parameters, such as dihedral angles, put in evidence significant changes in the average conformation at the mesophase transitions. The conformations predicted by DFT have been validated by comparing the calculated (13)C chemical shifts with those experimentally observed for the alkoxylic carbons, whose relative orientation plays a key role in establishing the overall conformation of the molecule in each liquid crystalline phase. Furthermore, the orientational order parameters of the relevant flexible fragments were calculated and found to be in good agreement with those characterizing similar systems, thus validating our approach.

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“…For a long time catenanes and rotaxanes were only accessible in low yields by statistical or multistep syntheses . Now, however, certain types of these mechanically connected molecules including molecular knots can be produced in preparative amounts − using noncovalent supramolecular templating effects …”

Section: Introductionmentioning

confidence: 99%

Catenanes and Rotaxanes of the Amide Type

1996

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New catenane (cf 3) and rotaxane (cf 26) types have been obtained in remarkable yields via supramolecular template syntheses. The amide-based mechanically bonded structures can be designed by appropriate choice of building units. The selective formation of stable outlout, idin and idout [2]catenane isomers (cf Scheme 2), which were separated, allowed conclusions concerning their mechanism of formation. It was demonstrated that one of the two macromonocycles of the catenane molecule forms initially and acts as a host cavity for a building block of the second, interlocking macrocycle. This knowledge made a simple synthesis of amide-linked rotaxanes possible. The first X-ray structural analysis of a hano-catenane revealed a self-assembled, interlocked system held together by networks of inter-and intramolecular hydrogen bonds, including the amide groups and the h a n oxygen atoms. There is no doubt that these new intertwined amide systems will be extendable to higher catenanes and rotaxanes.Catenanes, rotaxanes and knots have become "Highlights" in supramolecular chemistry (1) thanks to more recent high yield syntheses via the use of supramolecular template effects (2). Amide-based catenanesDuring work on the syntheses of basket-shaped host molecules (3) we unexpectedly found an extremely simple catenane synthesis in 1992 (4). Catenane 3 could be prepared from the Simple components 1 and 2 in one step (Scheme 1) (5). As byproducts, the dimethoxy-substituted macromonocycle 4 was isolated along with the 72-membered "tetramer"

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Conformational properties of the THYME polyethers. The bis-THYME cylinder: a three-dimensional analog of 18-crown-6

Cited by 25 publications

References 0 publications

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Conformational Changes at Mesophase Transitions in a Ferroelectric Liquid Crystal by Comparative DFT Computational and ¹³C NMR Study

Catenanes and Rotaxanes of the Amide Type

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Conformational properties of the THYME polyethers. The bis-THYME cylinder: a three-dimensional analog of 18-crown-6

Cited by 25 publications

References 0 publications

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Conformational Changes at Mesophase Transitions in a Ferroelectric Liquid Crystal by Comparative DFT Computational and 13C NMR Study

Catenanes and Rotaxanes of the Amide Type

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Conformational Changes at Mesophase Transitions in a Ferroelectric Liquid Crystal by Comparative DFT Computational and ¹³C NMR Study