Octopus molecules at the air-water interface.  Mechanical control over tentacle orientation

Conner, Mark D.; Kúdelka, I.; Regen, Steven L.

doi:10.1021/la00053a028

Cited by 20 publications

(8 citation statements)

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“…Since their “re-discovery” in the 1970s, there has been considerable interest in the history, synthesis, host−guest properties, and potential applications of these molecules. − Surprisingly, little systematic attention has been directed to calixarenes at the air/water interface (A/W) despite the uses of phenol−formaldehyde resins, which are branched homologues of calixarenes, as surfactants in the recovery of oil from crude oil emulsions, and work with ionophoric Langmuir−Blodgett (LB) films of crown ethers and porphyrin derivatives transferred from A/W . The notable exception to this is a variety of monolayer-forming calixarenes which have been examined with respect to their possible use in membrane filters. − These include mercurated compounds, , cross-linkable derivatives, − calix[6]arene and p-tert -butylcalix[6]arene, and molecules with ethylene oxide polar headgroups . These studies primarily focused on surface pressure−area per molecule (Π− A ) isotherms at A/W.…”

Section: Introductionmentioning

confidence: 99%

Static and Dynamic Properties of Calixarene Monolayers at the Air/Water Interface. 1. pH Effects with p-Dioctadecanoylcalix[4]arene

et al. 1999

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Newly synthesized p-dioctadecanoylcalix[4]arene is shown to form stable monolayers at the air/water interface over a wide pH range (1.8−12). Surface pressure−area isotherms obtained with the Wilhelmy plate technique are used to infer that the molecular packing at the onset of film collapse is consistent with a conelike conformer having all of the phenol oxygens of the calixarenes adsorbed to the interface. Increasing pH leads to a stepwise dissociation to phenoxides and attendant expansion of the monolayer attributable to enhanced electrostatic repulsions among the negatively charged phenoxide polar heads. Analysis of the area per molecule as a function of pH reveals two distinct steps and an intermediate plateau. Considering the presence of two types of chemically inequivalent phenol groups and the potential for intramolecular hydrogen bonding, this behavior was interpreted in terms of acid−base equilibria in which the first step corresponds to an apparent surface pK a,1 ≈ 6.4 while the second step is consistent with an apparent surface pK a,2 ≈ 9.2 (assuming pK a,3, pK a,4 ≫ 12). As for the dynamics of the monolayers, the technique of surface light scattering (SLS) was employed to probe the surface viscoelasticity. Although pH had a dramatic effect on the molecular packing of p-dioctadecanoylcalix[4]arene monolayers, SLS results indicate that all films exhibited the limiting behavior of infinite lateral modulus dynamics when the surface pressure exceeds 1 mN·m-1, and such behavior is established to be independent of pH. From these findings, it is deduced that the packing of the aromatic rings and long octadecanoyl side chains, rather than electrostatic interactions of the phenoxide headgroups, is responsible for the lateral rigidity of such monolayers.

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Section: Introductionmentioning

confidence: 99%

Static and Dynamic Properties of Calixarene Monolayers at the Air/Water Interface. 1. pH Effects with p-Dioctadecanoylcalix[4]arene

et al. 1999

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“…We rationalised therefore that for further alkylations the use of stronger bases would be required. This was indeed the case, and we established that when using NaH in THF, 9, 10, 13, 14, and 15 were converted into their corresponding fully alkylated derivatives, compounds 19-23 in 45-76% yield ( Table 1, entries [11][12][13][14][15]. Again, only 2 equivalents of electrophile were used per phenolic OH, and the products were purified using alumina chromatography.…”

Section: Resultsmentioning

confidence: 80%

“…4,7-9 However, as with the calix [6]arenes most reports involve the addition of reactive or unfunctionalised electrophiles such as the benzyl halides. 4,7-10 Interesting exceptions include the preparation of octopus-type calix [6]arenes in low yield, 11 monosubstituted calix [8]arene using Cl(CH 2 CH 2 O) 3 Ts, 12 and the interbridging of calix [6]arenes and calix [8]arenes using mono-to tetraethylene glycol ditosylates. 13 Full ether functionalisations at the lower rim of calix [8]arenes have been reported, generally involving the use of large excesses of strong bases together with a large excess of a reactive electrophile such as the methyl or benzyl halides.…”

Section: Introductionmentioning

confidence: 99%

The selective functionalisation and difunctionalisation of p-substituted calix[6]arene and calix[8]arenes using hydrophilic moieties

et al. 2003

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Methodologies to access water soluble large ringed calixarenes in good yield using efficient synthetic procedures have been investigated. Symmetrical partial functionalisations at the lower rim are described using activated [n]ethylene glycol chains and the addition behaviour contrasted with that of bromoalkanenitriles which proceeds with no observed regioselectivity. Full functionalisations of the calixarenes bearing hydrophilic groups are then investigated and a two-step procedure established which appears to be generally applicable for the addition of different [n]ethylene glycol chains. Furthermore, difunctionalisation under different reaction conditions are described. Throughout, strategies for the characterisation of these high mass compounds are outlined.

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“…Copolymer films dissolved at a fluid−fluid interface are interesting for their intriguing surface properties. − Surface pressure vs molecular area isotherms of copolymer monolayers at an air−water (A/W) interface have shown a variety of interesting properties. ,,− , Interesting behaviors like novel surface micelle formation by diblock copolymers have also been observed recently. , However, the only experiment available where the quality of one of the solvents forming the interface has been changed and the corresponding effect on the interfacial viscoelastic properties has been measured has been performed with very low molecular weight poly(ethylene oxide)−polystyrene block copolymer at the A/W and oil−water interfaces by Sauer et al…”

Section: Introductionmentioning

confidence: 99%

Capillary Wave Studies of Polystyrene-b-poly(methacrylic acid) Diblock Copolymer Films at the Air−Water Interface

Gandhi¹,

Maher²,

Shaffer³

et al. 1997

Langmuir

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We have used mechanically generated capillary wave and ellipsometric techniques to investigate interfacial viscoelastic properties of adsorbed monolayers of polystyrene-b-poly(methacrylic acid) diblock copolymer at an air−water interface, as a function of both the overall molecular weight, M w, and the nominal interfacial number density of the copolymer. This experiment is a follow-up of our earlier experiment, in which we studied adsorbed monolayers of the same diblock copolymer at the toluene−water interface (Macromolecules 1993, 26, 6595). Now we have changed the environment of the polystyrene block from toluene to air and have studied the effect of such a change. The most prominent effect of this change is that it is more difficult to attain equilibrium at the air−water interface. Unlike the toluene−water case, no clear saturation of surface pressure is observed at the air−water interface. The maximum surface pressure values measured at the air−water interface are smaller than the saturation surface pressure values in the toluene−water case for all the three molecular weights we have investigated. Ellipsometric study shows that only a very small fraction of the copolymer molecules added to the system is adsorbed at the air−water interface. However, substantial changes in the longitudinal elasticity and longitudinal viscosity are observed.

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Octopus molecules at the air-water interface. Mechanical control over tentacle orientation

Cited by 20 publications

References 0 publications

Static and Dynamic Properties of Calixarene Monolayers at the Air/Water Interface. 1. pH Effects with p-Dioctadecanoylcalix[4]arene

Static and Dynamic Properties of Calixarene Monolayers at the Air/Water Interface. 1. pH Effects with p-Dioctadecanoylcalix[4]arene

The selective functionalisation and difunctionalisation of p-substituted calix[6]arene and calix[8]arenes using hydrophilic moieties

Capillary Wave Studies of Polystyrene-b-poly(methacrylic acid) Diblock Copolymer Films at the Air−Water Interface

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