Helical aggregates from a chiral organogelator

Maitra, Uday; Potluri, Vijay; Sangeetha, N.; Babu, Ponnusamy; Raju, A. R.

doi:10.1016/s0957-4166(01)00073-8

Cited by 39 publications

(22 citation statements)

References 22 publications

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“…3a), suggesting the existence of stacked aromatic moieties in the gel that de-stack on melting. From this evidence along with previous results published in literature, 1,[16][17][18][19][20] it can be argued that the molecules were aggregating via both intermolecular hydrogen bonding (involving NÀ ÀH and C¼ ¼O) and stacking involving interactions between p electrons of neighboring molecules. The spectra recorded by heating the gels showed an increase in intensity and a blue-shift to 447 nm of the band originally at about 460 nm, and a merging of the band at 425 nm and the shoulder at about 500 nm.…”

Section: Resultssupporting

confidence: 77%

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Chirality driven self‐assembly in a fluorescent organogel

et al. 2011

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In this work, we present the characterization of an enantiomeric pair of fluorescent dye organogelators and the properties of their stable gel at low concentration in organic solvents. The gels of both enantiomers and of their mixtures were analyzed by differential scanning calorimetry, circular dichroism (CD), atomic force microscopy, UV-vis absorption, and fluorescence. The acquired data were supported by molecular modeling of the helical assembly of the gelators and by the simulation of their CD spectra by means of DeVoe method, and suggested the occurrence of an enantiomeric discrimination process during the formation of the gels.

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Section: Resultssupporting

confidence: 77%

“…The curve obtained by reporting the absorbance at 447 nm as a function of cooling temperature has a typical S-shape and it has been observed in other systems undergoing a sol-gel transition. 16,17 The fluorescence emission obtained by pumping the gel at 280 nm exhibited a similar behavior (Fig. 4b).…”

Section: Resultsmentioning

confidence: 53%

Chirality driven self‐assembly in a fluorescent organogel

et al. 2011

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“…[72][73][74][75][76] With the exception of the tartrate gelators explored by Oda and co-workers, [77] it is difficult to pinpoint the relationship between molecular and strand asymmetry. [73,74] By using a series of alkylated ureas and thioureas with only one center of chirality and in which that center can be moved systematically along the alkyl chain, it should be possible to determine the relationship between molecular and aggregate chiralities.…”

Section: Full Papermentioning

confidence: 99%

Urea and Thiourea Derivatives as Low Molecular‐Mass Organogelators

George

Tan

John

et al. 2005

Chemistry A European J

164

108

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The properties of a series of organogels consisting of a urea or thiourea derivative with one or two n-alkyl substitutuents at the nitrogen atoms (a low molecular-mass organogelator (LMOG)) and an organic liquid are described. They include N,N'-dimethylurea, the LMOG of lowest molecular mass (M(W) 88) we are aware of. The efficiencies of the LMOGs, based the diversity of liquids gelated, the minimum amount required for gelation of a liquid at room temperature, and the temporal and thermal stabilities of the gels formed, have been investigated as a function of the number, length, and substitution pattern of their n-alkyl chains. The gels are thermally reversible and require generally very low concentrations (<2 wt %) of an LMOG. Some of the LMOGs with shorter chains are more efficient than their longer chained analogues. The structural and thermodynamic properties of the gels have been examined by IR, DSC, and X-ray diffraction techniques. Polarizing optical microscopic analyses of the gels show that the nature of gelator aggregates depends mainly on the alkyl chain length. Changes in the aggregation ability have been examined systematically by perturbing the molecular structure.

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“…Design and synthesis of new and simple organogelator has received significant recent attention. A large number of organogelators of different categories has been identified in recent years by different investigators 14–22. Physical gel formation can generally be best understood as resulting from competition between tendencies of the gelator to dissolve in the solvent and tendencies for it to self‐assemble 23–31.…”

Section: Introductionmentioning

confidence: 99%

Benzene physical and chemical organogels: Effect of network scaffolding on the thermodynamic behavior of entrapped solvent molecules

Markovic¹,

Ginic‐Markovic²,

Dutta³

2004

J of Applied Polymer Sci

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This paper presents a thermodynamic investigation of the benzene physical and chemical organogels, using differential scanning calorimetry (DSC) and intends to draw an appropriate relationship between the gel network structure and the properties. Physical gels, formed by an aluminium soap of fatty acid, and chemical gels, created by in situ cross-linking of a siloxane copolymer are investigated. The effects of the type and quantity of the gelators and their corresponding network mesh size distribution in the gels on crystallization, melting, and their kinetics are examined. It appears that the kinetics of crystallization of the entrapped solvent is significantly affected by the quality of the gel network scaffolding and can be treated successfully by the Avrami equation of crystallization. From the melting behavior of the entrapped solvent crystallites, quantitative information about the number of solvent molecules bound per molecule of the gelator has been extracted. DSC proves to be a reliable technique to evaluate the population distribution of solvent molecules trapped in the physical and chemical organogel network scaffolding. The state of the solvent may be treated as a probe to understand the structure of the gels.

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Helical aggregates from a chiral organogelator

Cited by 39 publications

References 22 publications

Chirality driven self‐assembly in a fluorescent organogel

Chirality driven self‐assembly in a fluorescent organogel

Urea and Thiourea Derivatives as Low Molecular‐Mass Organogelators

Benzene physical and chemical organogels: Effect of network scaffolding on the thermodynamic behavior of entrapped solvent molecules

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