Molecular interactions between organized, surface-confined monolayers and vapor-phase probe molecules: hydrogen-bonding interactions

Sun, Li; Kepley, Larry J.; Crooks, Richard M.

doi:10.1021/la00045a006

Cited by 123 publications

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“…In particular, it was shown that the amine forms a stable monolayer on the Au surface [33], using amine in liquid phase (as we did) as in vapour phase [35][36][37][38]. After that, the complexes are easily oxidized (this is a redox reaction) leading to the dissolution of the first metallic layer.…”

Section: Discussionmentioning

confidence: 80%

Is gold always chemically passive?

Aufray

Roche

2008

Applied Surface Science

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. AbstractWhen epoxy-amine liquid mixtures are applied onto metallic substrates (such as Al, Ti, Sn, Zn, Fe, Cr, Cu, Ag, Ni, and Au), concomitant amine chemisorption and metallic surface dissolution occur, leading to organo-metallic complex formation. The interphase formation was studied, using two different amines as hardener (IsoPhoroneDiAmine and DiEthyleneTriAmine). If the complex concentration within the liquid amine or epoxyamine prepolymer was higher than its solubility limit, the complexes will crystallize. Sharp needle-like crystals were only observed with metal-IPDA organo-metallic complexes. A lot of metals are widely used as reactive substrates with gold as a reference, which is considered chemically inert. It is misleading, since it will be shown in this article that gold reacts with amine, just as the other metals.

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Section: Discussionmentioning

confidence: 80%

Is gold always chemically passive?

Aufray

Roche

2008

Applied Surface Science

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“…We have examined five types of chemical interactions that occur between monolayers and molecules: electrostatic binding, covalent linking, complexation interactions, proton transfer, and hydrogen bonding (9)(10)(11)(12)(13)(14). These interactions are five of the six tools presently in our "toolbox"; the sixth is a physical recognition strategy that is discussed later (6).…”

Section: Resultsmentioning

confidence: 99%

“…Figure 1 shows FTIR external reflection spectroscopy (FTIR-ERS) data for Au/HS(CH 2 ) 2 COOH and Au/HS(CH 2 ) 2 CH 3 surfaces after and before exposure to a saturated vapor of myristic acid, CH 3 (CH 2 ) 12 COOH. Prior to CH 3 (CH 2 ) 12 COOH modification, the Au/HS(CH2)2COOH spectrum, Figure Ib, indicates absorptions due to the acid C=O stretch and the enhanced a-CH2 scissors mode at 1722 and 1410 cm-1, respectively (15)(16)(17)(18).…”

Section: Resultsmentioning

confidence: 99%

“…It has been shown previously that a 16 cm-1 shift in the C=O stretching frequency of n-alkanoic acids from about 1726 to 1710 cm-1 corresponds to a structural change from laterally hydrogen-bonded to a face-toface dimer configuration (15,17). Based on the observed frequency shift of 5 cr-1 , we propose a model in which adsorbed CH 3 (CH 2 ) 12 COOH is hydrogen-bonded to surface-confined HS(CH 2 ) 2 COOH in both face-to-face and lateral configurations; that is, a dynamic superposition of the two configurations shown at the bottom of Scheme II.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Characterization of Two-Dimensional Molecular Recognition Interfaces

Crooks

Chailapakul

Ross

et al. 1994

Interfacial Design and Chemical Sensing

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This document has been approved for public release and sale; N00179 its distribution is unlimited. ABSTRACT (Maximum200 words)We have used self-assembly chemistry to synthesize monolayer assemblies that function as molecular recognition interfaces. In the first part of this paper, we show that onecomponent self-assembled n-alkanethiol monolayers with carboxylic acid functionalized -endgroups specifically adsorb vapor-phase acid-terminated molecules via hydrogen bonding or vapor-phase amine-terminate molecules via proton-transfer interactions. In the second part, we demonstrate that two-component monolayers, which consist of inert n-alkanethiol framework moleculesanddefect-inducing templat• molecules, can discriminate between "--solution-phase probe molecules based on their physical and chemical characteristics. By electrochemically etching the defects and then imaging the resulting surface by scanning tunneling microscopy the defect sites can be indirectly visualized. 93-2922393 1-. We have used self-assembly chemistry to synthesize monolayer .7 assemblies that function as molecular recognition interfaces. In • Dist first part of this paper, we show that one-component selfassembled n-alkanethiol monolayers with carboxylic acid functionalized endgroups specifically adsorb vapor-phase acid-_.terminated molecules via hydrogen bonding or vapor-phase amineterminate molecules via proton-transfer interactions. In the second part, we demonstrate that two-component monolayers, which consist of inert n-alkanethiol framework molecules and defectinducing template molecules, can discriminate between solutionphase probe molecules based on their physical and chemical characteristics. By electrochemically etching the defects and then imaging the resulting surface by scanning tunneling microscopy the defect sites can be indirectly visualized.Molecular recognition is the selective binding of a probe molecule to a molecular receptor. This binding interaction relies on both non-covalent intermolecular chemical interactions, such as hydrogen bonding or van der Waals forces, and steric compatibility, such as size or shape inclusion. At present, a detailed understanding of molecular recognition phenomena is hindered primarily by two experimental problems. First, in many natural systems the receptor is a large, flexible, and complex molecule with many potential binding sites, and as a result it is difficult to quantify the specific types and magnitudes of interactions that lead to probe binding. Second, there are only a few analytical methods that are sufficiently specific and sensitive that they can be used for studying individual molecular interactions in bound probe/receptor complexes. These and other difficulties associated with natural systems have resulted in the synthesis of simpler model receptors and characterization of their interactions with probe molecules (1-3).Two general strategies have been used for synthesizing and characterizing model receptors and their complexes with probe molecules. The first is based on interactio...

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“…This indicates a possible lateral type of hydrogen bonding, as found previously in some polycarboxylic acid derivatives. [22] The 1 H NMR and FTIR results show that the gel aggregates of both the acid 15-5-H and the sodium salt 17-3-Na gelators are stabilized by cooperative hydrogen bonding between peptidic units and lipophilic interactions between alkyl chains. It should also be noted that the respective FTIR vibrations of both gelators in the spectra of their pxylene and o-xylene gels are practically identical, despite the fact that both showed much more efficient gelation of the former solvent.…”

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confidence: 97%

Positionally Isomeric Organic Gelators: Structure–Gelation Study, Racemic versus Enantiomeric Gelators, and Solvation Effects

Čaplar

Frkanec

Vujičić

et al. 2010

Chemistry A European J

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Low molecular weight gelator molecules consisting of aliphatic acid, amino acid (phenylglycine), and omega-aminoaliphatic acid units have been designed. By varying the number of methylene units in the aliphatic and omega-aminoaliphatic acid chains, as defined by descriptors m and n, respectively, a series of positionally isomeric gelators having different positions of the peptidic hydrogen-bonding unit within the gelator molecule has been obtained. The gelation properties of the positional isomers have been determined in relation to a defined set of twenty solvents of different structure and polarity and analyzed in terms of gelator versatility (G(ver)) and effectiveness (G(eff)). The results of gelation tests have shown that simple synthetic optimizations of a "lead gelator molecule" by variation of m and n, end-group polarity (carboxylic acid versus sodium carboxylate), and stereochemistry (racemate versus optically pure form) allowed the identification of gelators with tremendously improved versatility (G(ver)) and effectiveness (G(eff)). Dramatic differences in G(eff) values of up to 70 times could be observed between pure racemate/enantiomer pairs of some gelators, which were manifested even in the gelation of very similar solvents such as isomeric xylenes. The combined results of spectroscopic ((1)H NMR, FTIR), electron microscopy (TEM), and X-ray diffraction studies suggest similar organization of the positionally isomeric gelators at the molecular level, comprising parallel beta-sheet hydrogen-bonded primary assemblies that form inversed bilayers at a higher organizational level. Differential scanning calorimetry (DSC) studies of selected enantiomer/racemate gelator pairs and their o- and p-xylene gels revealed the simultaneous presence of different polymorphs in the racemate gels. The increased gelation effectiveness of the racemate compared to that of the single enantiomer is most likely a consequence of its spontaneous resolution into enantiomeric bilayers and their subsequent organization into polymorphic aggregates of different energy. The latter determine the gel fiber thickness and solvent immobilization capacity of the formed gel network.

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Molecular interactions between organized, surface-confined monolayers and vapor-phase probe molecules: hydrogen-bonding interactions

Cited by 123 publications

References 0 publications

Is gold always chemically passive?

Is gold always chemically passive?

Synthesis and Characterization of Two-Dimensional Molecular Recognition Interfaces

Positionally Isomeric Organic Gelators: Structure–Gelation Study, Racemic versus Enantiomeric Gelators, and Solvation Effects

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