Small depsipeptides as solvent gelators

Devries, Ej; Kellogg, R. M.

doi:10.1039/c39930000238

Cited by 82 publications

(48 citation statements)

References 8 publications

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“…[3] We have been interested in the gelation of organic solvents induced by small organic molecules and in the way that gelation phenomena are coupled with the formation of large supramolecular assemblies. [4] However, the structures of such gels are poorly understood, and serendipity appears to have been the major guiding principle in this particular area. [4,5] Most of the gelating molecules known so far possess at least one moiety that can participate in highly directional noncovalent interactions with other gelator molecules.…”

Section: Introductionmentioning

confidence: 99%

“…[4] However, the structures of such gels are poorly understood, and serendipity appears to have been the major guiding principle in this particular area. [4,5] Most of the gelating molecules known so far possess at least one moiety that can participate in highly directional noncovalent interactions with other gelator molecules. Aggregation of these molecules can, for instance, lead to extended one-dimensional arrays of hydrogen bonds.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Self‐Assembly of Bisurea Compounds in Organic Solvents and on Solid Substrates

Esch

Feyter

Kellogg

et al. 1997

Chemistry A European J

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234

105

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New low molecular weight gelators based on the structure R-NHCONH-X-NHCONH-R have been synthesized and tested for their ability to cause gelation of organic solvents. Compounds 2 (R = ndodecyl, X = -(CH 2 ) 9 -), 3 (R = n-dodecyl, X = -(CH 2 ) 12 -), 4 (R = n-dodecyl, X = 4,4´-biphenyl), and 5 (R = benzyl, X = -(CH 2 ) 9 -) form thermoreversible gels with a wide range of organic solvents, at concentrations well below 10 mg mL -1 . Depending on the nature of the R and X groups, the solvents that undergo gelation include hexadecane, p-xylene, 1-octanol, n-butyl actetate, cyclohexanone, and tetralin. The gels are stable up to temperatures well above 100 °C, but are easily disrupted by mechanical agitation. Light microscopic investigations revealed that compounds 2-5 spontaneously aggregate to form thin flat fibers, which can be several hundreds of micrometers long and only 2-10 µm wide. Depending on the solvent, multiple twists in the fibers are observed. In the gels, these fibers form an extended three-dimensional network, which is stabilized by multiple mechanical contacts between the fibers. Electron microscopy and X-ray powder diffraction revealed that the fibers consist of stacks of sheets. The thickness of the sheets is 3.65 and 3.85 nm for 2 and 3, respectively.Scanning tunneling microscopic investigations of 2 absorbed on graphite showed that 2 forms long ribbons with a width of 5.0 nm. In the ribbons the molecules have a parallel arrangement, with the long molecular axis perpendicular to the long ribbon axis. The two urea groups within a given molecule are each part of mutually parallel extended chains of hydrogen bonds. Based on these observations a model is proposed for the arrangement of the molecules in the fibers. In this model the bisurea molecules aggregate through hydrogen-bond formation into long ribbons, which assemble into sheets. In these sheets the ribbons are tilted. Finally, the sheets stack to form long thin fibers. This model is supported by molecular dynamics simulations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self‐Assembly of Bisurea Compounds in Organic Solvents and on Solid Substrates

Esch

Feyter

Kellogg

et al. 1997

Chemistry A European J

Self Cite

234

105

View full text Add to dashboard Cite

show abstract

“…One of the advantages of the developed BML enzymatic assay was the possibility of analysing up to 20 samples per hour, both for D-and L-lactate. In comparison, capillary electrophoresis, which can detect six different analytes in the same sample, allows the determination of only four samples per hour, without resolution of D-and L-lactate [9]. No significant interferences for the lactate sensor were found.…”

Section: Lactate Assay In Beermentioning

confidence: 99%

“…Several highly sophisticated methods, both chromatographic and electrophoretic, have been used to determine lactic acid in beer [7][8][9]. However they need pretreatment of samples to be analysed and they can not distinguished between lactate isomer forms.…”

Section: Introductionmentioning

confidence: 99%

Luminescent enzymatic flow sensor for d- and l-lactate assay in beer

Girotti

Muratori

Fini

et al. 2000

Eur Food Res Technol

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A bioluminescent flow sensor, previously developed for the determination of both D-and L-lactate in clinical samples, was utilized to carry out the same assay in beer. The sensor monitored the reduced form of nicotinamide adenine dinucleotide, produced by nylon-immobilized D-and L-lactate dehydrogenase, by means of bacterial bioluminescent enzymes immobilized on a separate nylon coil. The preparation of beer samples was very simple as only a modification of pH and a dilution were necessary. The recoveries ranged from 91% to 104%, and the relative standard deviations at the 1 mmol 1 -1 level were 4.6% and 6.7% for Land D-lactate respectively. The response was linear in the range 0.1-10 mmol 1 -1 for both D-and L-lactate. The total amount of lactate determined by bioluminescent biosensor (x) and by HPLC (y) showed a very good correlation (yp0.654 xc88.1, np29, rp0.918). The flow injection system developed allowed the determination of not only the total but also the individual contents of D-and L-lactate in beer, and the timely discovery of the unwanted presence of lactic acid bacteria.

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“…From transmission electron microscopy (TEM) it was found that the gel consists of a network of fibers. The depsipeptide 14 was found to gelate a few solvents, among which polar (MeCN) and apolar (Et 2 O) solvents [22]. Because 14 does not dissolve in these solvents, a pre-solubilization step with a droplet of methanol is required.…”

Section: Figure 4 Amide and Carbohydrate Containing Gelatorsmentioning

confidence: 99%