Two dimensional self-assembly of bis-acylureas having various functional end groups

Kim, Jong-Uk; Davis, Riju; Zentel, Rudolf

doi:10.1016/j.jcis.2011.04.022

Cited by 13 publications

(11 citation statements)

References 27 publications

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“…The basic molecular design strategy here involves ( a ) the utility of hydrogen bonding interactions that are proximally located with aromatic rings to have correlated hydrogen-bonding and π−π interactions; In fact, molecules with similar structure have been reported as small molecule gelators, owing to the self-assembly ability provided by strong interactions. [8a] ( b ) an alkyl chain linking the urea-based aromatic units with an ionic head group, where the alkyl chain provides the hydrophobic interactions to reinforce the assembly in the aqueous phase and finally ( c ) the ionic head groups on either side of the molecules to introduce repulsive forces that presumably mitigate inter-layer interactions and thus avoid the need for exfoliation steps to achieve ultrathin O2D sheets.…”

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Smart Organic Two‐Dimensional Materials Based on a Rational Combination of Non‐covalent Interactions

et al. 2016

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Rational design of organic 2D (O2D) materials has made some progress, but is still in its initial stages. Here, we report on a class of self-assembling small molecules that form nano/microscale supramolecular 2D materials in aqueous media. We show that a judicial combination of four different intermolecular interactions forms the basis for the robust formation of these ultra-thin assemblies. We also show that these assemblies can be programmed to disassemble in response to a specific protein and release its non-covalently bound guest molecules.

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confidence: 99%

“…To further understand the design rules in aqueous media, compared to those in organic solvents, [8] we systematically varied the structure of the molecule.…”

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Smart Organic Two‐Dimensional Materials Based on a Rational Combination of Non‐covalent Interactions

et al. 2016

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“…22 Among others, Zentel and co-workers reported a couple of bis-acylurea compounds possessing a C 5 or C 6 alkyl spacer with different functional end groups. 30,31 An in-depth understanding of the formation of these nanosheets is still challenging. It is quite evident that hydrogen bonding is important.…”

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confidence: 99%

NMR-crystallographic study of two-dimensionally self-assembled cyclohexane-based low-molecular-mass organic compounds

et al. 2013

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Using a combined approach based on scanning electron microscopy, powder X-ray diffraction as well as 1D and 2D multinuclear solid-state NMR spectroscopy, we were able to determine the morphology and the crystal structures for a set of three supramolecular compounds with different hydrogen bonding motifs, namely N,N′-(cyclohexane-trans-1,4-diyl)bis(2,2-dimethylpropanamide) 1, 1,1′-(cyclohexane-trans-1,4-diyl)bis(3-tert-butylurea) 2 and N 1 ,N 4-bis(tert-butylcarbamoyl)cyclohexane-trans-1,4-dicarboxamide 3. Based on a complete signal assignment of the 1D solid-state MAS NMR spectra (1 H, 13 C, 15 N) employing 2D HETCOR experiments and a quantitative evaluation of the corresponding resonances, the content of the asymmetric unit was determined to one half of a molecule. Probing the molecular configuration with 1 H-1 H double-quantum experiments revealed an intramolecular hydrogen bond for compound 3 while 1 and 2 form exclusively intermolecular H-bonds. Ab initio structure solutions applying real space methods with an included close-contact penalty were carried out for all compounds. The following Rietveld refinements led to excellent wR p-values between 2.5% and 4.1%. Compounds 1 and 2 crystallise isostructurally in the monoclinic space group P2 1 /c exhibiting a pseudo-biaxial hydrogen bond motif. 3 crystallises in the triclinic space group P1 with intermolecular head-to-tail hydrogen bonds connecting the molecules to one-dimensional ribbons. Nevertheless, all compounds grow in a sheet-like morphology with lateral dimensions of several hundred micrometres indicating a fast growth in two dimensions along two of the crystal axes. Since all three molecules possess inversion symmetry cancelling the molecular dipole moment the growth mechanism itself has to be dominantly driven by the formation of hydrogen bond networks.

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“…[1] Ureas have been utilized as a microbial alkaline protease inhibitor, [2] HIV-1 protease inhibitor, [3] CCK-B receptor antagonists, [4] endothelin antagonists, [5] p38 MAP kinase inhibitors. [6] They are essential functional groups employed in agrochemicals (such as diuron, monouron, isoproturon), material science , [7] and polymer chemistry. The worldwide production of polymers like polyurethane [8] indicates the importance of their synthetic intermediate.…”

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Ethyl‐2‐Cyano‐2‐(2‐Nitrophenylsulfonyloximino)Acetate (ortho‐NosylOXY) Mediated One‐Pot Racemization Free Synthesis of Ureas, Carbamates, and Thiocarbamates via Curtius Rearrangement

et al. 2021

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Direct conversion of carboxylic acids to ureas, carbamates, and thiocarbamates in a single pot via Curtius rearrangement is accomplished. One recently established coupling reagent, Ethyl-2-cyano-2-(2-nitrophenylsulfonyloximino)acetate (ortho-NosylOXY, I), is successfully used for the racemization free synthesis of ureas, di-peptidyl ureas, and carbamates with moderate to good yield (82-69%). This single-pot hassle-free procedure works with a diverse range of N-protecting groups Fmoc, Boc, and Cbz. Various amine, including aromatic, methyl esters of amino acids, t-butylamine, alcohols, and thiols, are used as nucleophiles. A detailed NMR-based mechanism study is incorporated here. Racemization suppression, easy removal of by-products, and less waste generation make this methodology useful.

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Two dimensional self-assembly of bis-acylureas having various functional end groups

Cited by 13 publications

References 27 publications

Smart Organic Two‐Dimensional Materials Based on a Rational Combination of Non‐covalent Interactions

Smart Organic Two‐Dimensional Materials Based on a Rational Combination of Non‐covalent Interactions

NMR-crystallographic study of two-dimensionally self-assembled cyclohexane-based low-molecular-mass organic compounds

Ethyl‐2‐Cyano‐2‐(2‐Nitrophenylsulfonyloximino)Acetate (ortho‐NosylOXY) Mediated One‐Pot Racemization Free Synthesis of Ureas, Carbamates, and Thiocarbamates via Curtius Rearrangement

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