Decyl Chains Research Articles

Liquid crystalline behaviour of symmetrical thermotropic Schiff base compounds

A series of new symmetrical liquid crystal compounds with Schiff base as a linking unit attached to different terminal alkyl chains were synthesized and characterized. The intermediates of 4-(decyloxy)benzaldehyde, 4-(dodecyloxy)benzaldehyde, and 4-(tetradecyloxy)benzaldehyde were synthesized through alkylation reaction between 4-hydroxybenzaldehyde with three series of bromoalkanes. Next, it further reacted with 1,4-phenylenediamine through condensation reaction to produce symmetrical Schiff base linkage with different terminal group chain which indicated as N-(substitutedbenxylidene)benzene-1,4-diamine. The compounds were characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and CHN elemental analysis. The Schiff base linkages are detectable in the FTIR spectra within the range of 1601–1604 cm⁻¹ and in the NMR spectra at δ 8.47–8.48 ppm. The mesophase transition phase of this compounds were determined using polarized optical microscope (POM) and further confirmed using differential scanning calorimetry (DSC). The Schiff base compounds were found to be mesogenic with smectic C and nematic transitions phases. These compounds attached to decyl, dodecyl, and tetradecyl terminal chains were found to exhibit smectic C phase at 142.47, 135.60, and 131.90 °C and nematic phase at 199.62, 197.11, and 188.76 °C, respectively. The incorporation of a Schiff base linking unit with a symmetrical alkyl chain induces the mesogenic effect in the molecules. A long alkyl chain allows the compounds to adopt a lamellar packing, facilitating the formation of a smectic phase. Incorporating the Schiff base into the molecules maintains an appropriate permanent dipole moment, which enables the homologs to arrange in a parallel orientational order, thereby adopting a nematogenic character.

Synthesis of poly(ionic liquid-OH) mediated deacetylated chitin and its hydrogels: A study on their applications in controlled release of paracetamol and urea

Due to the biodegradable and biocompatible nature of chitin and chitosan, they are extensively used in the synthesis of hydrogels for various applications. In this work, deacetylation of chitin is carried out with alkaline poly(dimethyldiallylammonium-hydroxide) that gave a higher amount of water-soluble chitin (with 84 % of the degree of deacetylation = chitosan0.84) compared to deacetylation using NaOH. The water-soluble chitosan0.84 is used as intercalating chains for the preparation of acrylic acid and vinylimidazole-based hydrogels. The quaternization of imidazole groups is done with 1,ω-dibromoalkanes, which sets off the crosslinking in the above polymer network. A set of three chitosan0.84 intercalated hydrogels, namely Cs-C4-hydrogel, Cs-C5-hydrogel, and Cs-C10-hydrogel are prepared bearing butyl, pentyl, and decyl chains as respective crosslinkers. The swell ratios of these intercalated hydrogels are compared with those of non-intercalated hydrogels (C4-hydrogel, C5-hydrogel, and C10-hydrogel). Chitosan0.84 intercalated Cs-C10-hydrogel has excellent swelling properties (2330 % swelling ratio) among six synthesized hydrogels. SEM analysis reveals that decyl crosslinker-bearing hydrogels are highly porous. The multi-functionality of Cs-C10-hydrogel and C10-hydrogel is explored towards -the controlled release of paracetamol/urea, and methyleneblue dye absorption. These studies disclose that chitosan0.84 intercalated hydrogels are showing superior-swelling behavior, high paracetamol/urea loading capacities and better dye entrapment than their non-intercalated counterparts.

Phase behavior of lyotropic alkyl thioglycolipid surfactants: Effects of sugar headgroup and alkyl tail length

AbstractThe lyotropic properties of alkyl thioglycosides with varying sugar headgroup (lactose, cellobiose, maltose, galactose, or glucose) and alkyl chain length (octyl, decyl, or dodecyl chains) are investigated by surface tensiometry, visual observation, and fluorescence spectroscopy. The results substantiate that the glycosidic S‐linkage confers considerably different solution aggregation behavior on these surfactants relative to their O‐linked counterparts, where the properties of the latter are known. The materials properties of the aggregated structures from the alkyl thioglycosides vary considerably. Micelles are formed by octyl thiocellobioside and all alkyl thiomaltosides. Turbid aggregate solutions are formed by the alkyl thioglucosides and octyl thiogalactoside, whereas the longer chain alkyl thiogalactosides are minimally soluble. Fluorescence spectroscopy of these systems confirms their aggregation in lamellar‐like structures. The alkyl thiocellobiosides and alkyl thiolactosides form hydrogels from these low‐molecular weight materials at concentrations almost an order of magnitude lower than gels using other low‐molecular weight materials. Here, hydrogels form at concentrations <0.3 wt% with some forming hydrogels at concentrations as low as 0.03 wt% from alkyl thiocellobiosides and thiolactosides, with hydrogel properties differing significantly with this slight change in the sugar headgroup. Alkyl thiocellobiosides form a nanofiber network and alkyl thiolactosides form globular hydrogels. Overall, these results clearly document materials properties that can readily be controlled and designed depending on molecular structure.

Crystalline bilayer formation in homoleptic low-spin Fe(II) compounds with alkyl chain substituents.

A series of asymmetric, homoleptic Fe(II) compounds based on the facially-binding tridentate ligand N-methyl-1,1-di(pyridin-2-yl)Cn-amine (LCn) (Cn = butyl, hexyl, octyl, decyl, dodecyl, tetradecyl and hexadecyl alkyl chains) with formula [FeII(LCn)2](X)2·solvate, where n = 4, 14 and X = BF4 (1C4 and 1C14) or n = 6, 8, 10, 12, 16 and X = CF3SO3 (1C6-1C12 and 1C16), are reported. Complexes 1C6 to 1C16 pack in crystalline bilayers in the solid state, forming hydrophobic and hydrophilic regions between adjacent layers of complexes. The combination of short Fe-N bond distances (∼2.00 Å) and SQUID magnetic susceptibility measurements show that the complexes are in the low-spin state across all measured temperature ranges. Differential scanning calorimetry confirmed phase transitions occur in compounds 1C6, 1C12, 1C14 and 1C16 upon heating from room temperature. The lack of any spin transitions and thermal stability conferred by thermogravimetric analysis over this temperature range suggest that these transitions are crystallographic in nature. 1H NMR studies show that the low-spin Fe(II) centres undergo partial conversion to paramagnetic species in solution. UV-vis spectroscopy in a range of common organic solvents show that the central Fe ions remain in the +2 oxidation state, suggesting that the increase in magnetic susceptibility in solution is likely due to partial spin-crossover, or due to speciation, in which a proportion of the compounds are high-spin Fe(II) complexes.

Tailoring amide N-substitution to direct liquid crystallinity in benzanilide-based dimers

The design of liquid crystalline dimers containing tertiary benzanilide groups has proved challenging due to their strong preference for the E amide conformation. In this work we have investigated the effect of different N-substituents on the amide conformation of model benzanilide monomers and found this had effectively no effect on conformation. Based on this observation, we investigated the effect of introducing large, flexible decyl chains at the amide nitrogen and compare their properties to the corresponding benzanilide-based dimers with lateral methyl substituents. The introduction of the decyl chain decreases the melting temperatures, and the tendency to crystallise, promoting glassy behaviour. This allows for nematic behaviour to be seen to much lower temperatures.

Supercritical Fluid Nanospray Mass Spectrometry: II. Effects on Ionization.

Nanospraying supercritical fluids coupled to a mass spectrometer (nSF-MS) using a 90% supercritical fluid CO2 carrier (sCO2) has shown an enhanced desolvation compared to traditional liquid eluents. Capillaries of 25, 50, and 75 μm internal diameter (i.d.) with pulled emitter tips provided high MS detection sensitivity. Presented here is an evaluation of the effect of proton affinity, hydrophobicity, and nanoemitter tip size on the nSF-MS signal. This was done using a set of primary, secondary, tertiary, and quaternary amines with butyl, hexyl, octyl, and decyl chains as analytes. Each amine class was analyzed individually to evaluate hydrophobicity and proton affinity effects on signal intensity. The system has shown a mass sensitive detection on a linear dynamic range of 0.1-100 μM. Results indicate that hydrophobicity has a larger effect on the signal response than proton affinity. Nanospraying a mixture of all amine classes using the 75 μm emitter has shown a quaternary amine signal not suppressed by competing analytes. Competing ionization was observed for primary, secondary, and tertiary amines. The 75 and 50 μm emitters demonstrated increased signal with increasing hydrophobicity. Surprisingly, the 25 μm i.d. emitter yielded a signal decrease as the alkyl chain length increased, contrary to conventional understanding. Nanospraying the evaporative fluid in a sub-500 nm emitter likely resulted in differences in the ionization mechanism. Results suggest that 90% sCO2 with 9.99% methanol and 0.01% formic acid yielded fast desolvation, high ionization efficiency, and low matrix effect, which could benefit complex biological matrix analysis.

Cataleptogenic Effect of Haloperidol Formulated in Water-Soluble Calixarene-Based Nanoparticles.

In this study, a water-soluble form of haloperidol was obtained by coaggregation with calix[4]resorcinol bearing viologen groups on the upper rim and decyl chains on the lower rim to form vesicular nanoparticles. The formation of nanoparticles is achieved by the spontaneous loading of haloperidol into the hydrophobic domains of aggregates based on this macrocycle. The mucoadhesive and thermosensitive properties of calix[4]resorcinol-haloperidol nanoparticles were established by UV-, fluorescence and CD spectroscopy data. Pharmacological studies have revealed low in vivo toxicity of pure calix[4]resorcinol (LD50 is 540 ± 75 mg/kg for mice and 510 ± 63 mg/kg for rats) and the absence of its effect on the motor activity and psycho-emotional state of mice, which opens up a possibility for its use in the design of effective drug delivery systems. Haloperidol formulated with calix[4]resorcinol exhibits a cataleptogenic effect in rats both when administered intranasally and intraperitoneally. The effect of the intranasal administration of haloperidol with macrocycle in the first 120 min is comparable to the effect of commercial haloperidol, but the duration of catalepsy was shorter by 2.9 and 2.3 times (p < 0.05) at 180 and 240 min, respectively, than that of the control. There was a statistically significant reduction in the cataleptogenic activity at 10 and 30 min after the intraperitoneal injection of haloperidol with calix[4]resorcinol, then there was an increase in the activity by 1.8 times (p < 0.05) at 60 min, and after 120, 180 and 240 min the effect of this haloperidol formulation was at the level of the control sample.

Conformational Change of Alkyl Chains at Phase Transitions in Thin Films of an Asymmetric Benzothienothiophene Derivative.

Among many promising organic semiconducting materials, 2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10) shows outstanding device performances for organic field-effect transistors. This compound has a highly ordered liquid crystalline state, i.e., the smectic E (SmE) phase. Although the transition from the crystalline state to the SmE phase is believed to accompany melting of the alkyl chains, no spectroscopic evidence has been found so far. In this study, the conformational change of the decyl chains in Ph-BTBT-C10 films across the phase transition is analyzed by temperature-dependent measurements in situ using infrared spectroscopy. The spectral analysis reveals that the polycrystalline film has latent conformational disorder (the gauche conformer), the rate of which becomes more pronounced with the heat treatment. As expected, melting of the decyl chains is observed above the transition temperature to the SmE phase. This study also highlights the discovery of some key bands sensitive to the phase transitions in liquid crystalline organic semiconductors.

The Impact of a 1,2,3-Triazole Motif on the Photophysical Behavior of Non-K Tetrasubstituted Pyrene with a Substitution Pattern Providing the Long Axial Symmetry.

1,3,6,8-Tetrasubstituted pyrene derivatives with two types of substituents (4-(2,2-dimethylpropyloxy)pyridine, 1-decyl-1,2,3-triazole, 1-benzyl-1,2,3-triazole, and pyrazole), substituted in such a way that provides the long axial symmetry, are prepared and characterized in the present study. To the best of our knowledge, the pyrene derivative containing the same heteroaryl motif (triazole) but substituted by two various alkyls, straight decyl and benzyl-based side chains (C), is reported for the first time. For comparison, compounds with one kind of triazole motif and substituted pyridine or pyrazole groups were prepared (A and B). The photophysical properties of all molecules were evaluated by thermogravimetric analysis (TGA) and UV-Vis spectroscopy (absorption and emission spectra, quantum yields, and fluorescence lifetimes). The obtained results were compared to analogues substituted at the 1,3,6,8 positions by one kind of substituent and also with all the 1,3,6,8-tetrasubstituted pyrenes reported in the literature substituted by two kinds of substituents with a substitution pattern that provides long axial symmetry. In addition, theoretical studies based on DFT and TD-DFT were performed that supported the interpretation of the experimental results. The photophysical properties of tetrasubstituted pyrene derivatives having triazole units at the 1,8-positions, respectively, and other identical substituents at the 3,6 positions show the dominance of triazole units in the pyrene framework; the dominance is even higher in the case of the substitution of 1,3,6,8 positions by triazoles, but containing two various alkyls.

Significant Effect of the Flexibility of Bridging Alkyl Chains on the Proximity of Stacked Porphyrin and Phthalocyanine Conjugated with a Fourfold Rotaxane Linkage.

Spatial distance is an important factor in controlling the functional interactions between molecular units in a conjugate; therefore, the bridging unit has been closely examined. Here, we examined the effect of the flexibility of bridging alkyl chains on the proximity of stacked porphyrin and phthalocyanine conjugated with a fourfold rotaxane linkage. We found that closely stacking two π systems requires bridging alkyl chains above a certain length, and the shorter bridges hinder stacking because of their lower flexibility. The stacking distance between porphyrin and phthalocyanine in the conjugate with decyl (C10 ) chains was estimated to be 4.03 Å and showed a unique physical character arising from short-distance interactions. The longer alkyl chains minimized steric restriction inside the fourfold rotaxane and allowed efficient communication between the porphyrin and phthalocyanine units. This is due to the flexibility of the side chains.

Gemini surfactant based-organomontmorillonites: preparation, characterization and application in pickering emulsion

To investigate the efficiency of gemini surfactant based organoclays (OMts) for the stabilization of O/W emulsions, different ammonium gemini surfactants with semi-rigid hydrophobic chains and spacer lengths were used for the modification of sodium montmorillionite (Mt). The composition and morphology of the resulting organoclays were characterized by Fourier transform infraredspectroscopy, X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy and thermogravimetric analysis. The results showed that these surfactants are more efficient than conventional surfactants and hydrocarbon type gemini surfactant analogous in the modification of Mt. An important increase of the d-spacing values was obtained particularly for long hydrocarbon chains and spacers. The OMt’s thermal properties and hydrophobicity were also governed by the structure of surfactants. The stabilizing behavior of gemini surfactants, OMt as well as surfactant/OMt mixtures in oil/water (1:1, v/v) emulsions was investigated by macroscopic and microscopic morphological observations. Better stabilization was achieved by G(10-4-10) surfactant bearing decyl chains and OMts with high surfactant concentration.

Polar Side Chains Enhance Selection of Semiconducting Single-Walled Carbon Nanotubes by Polymer Wrapping

This paper describes the effectiveness of donor–acceptor (D-A) conjugated polymers to disperse and select for semiconducting single-walled carbon nanotubes (s-SWCNTs) when enhanced by the inclusion of polar oligoethylene glycol-based side chains, without altering the D–A backbone. We designed and synthesized two sets of naphthalenediimide(NDI)-alt-bithiophene(T2)-based conjugated polymers with one of two alkyl side chains (decyl and dodecyl chains) of different lengths and with or without polar triethylene glycol side chains. The resulting low-band-gap copolymers all effectively disperse and select for s-SWCNT, but the inclusion of polar side chains enhances the interactions between the polymer backbone and the walls of the s-SWCNTs relative to the polymers with only alkyl side chains. As a result, the wrapping and selection efficiency of the polymer-SWCNT systems with polar side chains are both significantly enhanced. We further optimized the binding energy and surface coverage by combining glycol ether and dodecyl side chains to maximize wrapping efficiency, leading to a field-effect mobility of 2.82 cm2 V–1 s–1 and on/off current ratios of ∼2 × 107 in polymer-wrapped SWCNTs. Our results provide insight into the role of the side-chain interactions in the polymer wrapping and dispersion technique, and, because we focus on manipulating side chains, they can be generalized for other conjugated polymer backbones.

External-stimulus-triggered conformational inversion of mechanically self-locked pseudo[1]catenane and gemini-catenanes based on A1/A2-alkyne-azide-difunctionalized pillar[5]arenes.

Herein, we report a methodology for constructing mechanically self-locked molecules (MSMs) through the efficient intramolecular copper(i)-catalyzed alkyne–azide cycloaddition (CuAAC) of self-threaded A1/A2-azido-propargyl-difunctionalized pillar[5]arenes. The obtained monomeric “pseudo[1]catenane” and dimeric “gemini-catenane” were isolated and fully characterized using mass spectrometry, nuclear magnetic resonance (NMR) spectroscopy, and X-ray crystallography. Upon investigation by 1H NMR spectroscopy in chloroform, the observed motion for the threaded ring in the pseudo[1]catenane was reversibly controlled by the temperature, as demonstrated by variable-temperature 1H NMR studies. Two gemini-catenane stereoisomers were also isolated in which the two pillar[5]arene moieties threaded by two decyl chains were aligned in different topologies. Furthermore, the conformational inversion of pseudo[1]catenane and the gemini-catenanes triggered by solvents and guests was investigated and probed using 1H NMR spectroscopy, isothermal titration calorimetry, and single-crystal X-ray analysis.

Influence of Site Pairing in Hydrophobic Silica-Supported Sulfonic Acid Bifunctional Catalysts.

Imparting hydrophobicity to solid acid catalysts is critical to regulating their performances by allowing the creation of a less polar environment and improved partitioning of the reactants. Here we present different approaches for the preparation of silica-based catalysts comprising sulfonic acid (-SO3H) sites and hydrophobic decyl (-C10) chains by either simultaneous or sequential postfunctionalization of an azide-functionalized mesoporous silica platform. This set of hybrid bifunctional catalysts is compared in the model esterification of octanol with acetic acid, and the influence of the preparation methods together with the resulting site spatial distribution is discussed. In parallel, we show that pairing the two functional groups affords a maximum synergistic effect compared to more traditional mixed catalysts with random distributions of acid and hydrophobic functions.

The kinetics of thermal decomposition of 1-alkyl-3-methylimidazolium chloride ionic liquids under isothermal and non-isothermal conditions

The thermal stability and decomposition kinetics of a series of 1-alkyl-3-methylimidazolium chloride ionic liquids with different alkyl chain lengths (ethyl, propyl, butyl, hexyl, and decyl) were investigated with isothermal and non-isothermal thermogravimetric analysis. Isothermal experiments were conducted at 100, 125, 150, 175, 200, and 225 °C in nitrogen atmosphere. Non-isothermal experiments were conducted from 25−650 °C with heating rates of 5, 10, 15, and 20 ℃/min. Under both heating modes, the ionic liquids with the longer alkyl chains were found to display lower thermal stability. The activation energies Ea determined from isothermal analysis ranged from 115-120 kJ/mol, except for the ionic liquid with the decyl chain, for which the value was higher (157 kJ/mol). The Ea determined by non-isothermal analysis were similar to the isothermal values for the ionic liquids with the ethyl and decyl chains, higher (144-154 kJ/mol) for the ionic liquids with the propyl and butyl chains, and lower (98 kJ/mol) for the ionic liquid with the hexyl chain. The pre-exponential factors ln(A) from isothermal analyses resulted in values in the range 25–29, which did not vary with reaction model. Non-isothermal analyses resulted in ln(A) values in the range 24–38, which were likewise not sensitive to reaction model. Among the models evaluated, the 3-dimensional reaction model was found to best represent both the isothermal and the non-isothermal data. No clear relationships were found between the alkyl chain length and the kinetic parameters.

Quantum Chemical and Electrochemical Evaluation of Alkyl Phosphine Oxide in Corrosion Inhibition of Carbon Steel in Formation Water

Abstract In this study, quantum chemical calculations and molecular dynamics simulations studies of a series of five nonionic surfactants namely: dimethyl alkyl phosphine oxide surfactants (C10-18PO) containing decyl, dodecyl-, tetradecyl-, hexadecyl-, and octadecyl alkyl chains were implemented using the density functional theory (DFT) method to interpret the correlation between the inhibition efficiency and the molecular structure of the different inhibitors in formation water. The global quantities including: highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital energy (LUMO), energy gap (ΔE), dipole moment (μ), total energy (TE), ionization potential (I), electron affinity (A), electronegativity (χ), chemical potential (π), global hardness (η), global softness (σ), global electrophilicity (ω), polarizabilities &lt;α&gt; and fraction of electrons transferred (ΔN) were calculated for the different inhibitors in formation water. The dependence of surface activities of the nonionic surfactants on the alkyl chain length was studied in distilled water. The surface activities and surface parameters of the studied surfactants were described using: surface tension and interfacial tension measurements. The determined surface parameters of the studied surfactants were surface tension, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area at 25 °C. The thermodynamic evaluation of the surfactants was performed by calculating the standard free energies of micellization and adsorption. The structure-corrosion inhibition performance was estimated using potentiodynamic polarization, electrochemical impedance measurements and quantum chemical studies at 25 °C in true sample formation water.

Kinetic Control in the Regioselective Alkylation of Pterin Sensitizers: A Synthetic, Photochemical, and Theoretical Study.

Alkylation patterns and excited-state properties of pterins were examined both experimentally and theoretically. 2D NMR spectroscopy was used to characterize the pterin derivatives, revealing undoubtedly that the decyl chains were coupled to either the O4 or N3 sites on the pterin. At a temperature of 70°C, the pterin alkylation regioselectively favored the O4 over the N3. The O4 was also favored when using solvents, in which the reactants had increased solubility, namely N,N-dimethylformamide and N,N-dimethylacetamide, rather than solvents in which the reactants had very low solubility (tetrahydrofuran and dichloromethane). Density functional theory (DFT) computed enthalpies correlate to regioselectivity being kinetically driven because the less stable O-isomer forms in higher yield than the more stable N-isomer. Once formed these compounds did not interconvert thermally or undergo a unimolecular "walk" rearrangement. Mechanistic rationale for the factors underlying the regioselective alkylation of pterins is suggested, where kinetic rather than thermodynamic factors are key in the higher yield of the O-isomer. Computations also predicted greater solubility and reduced triplet state energetics thereby improving the properties of the alkylated pterins as 1 O2 sensitizers. Insight on thermal and photostability of the alkylated pterins is also provided.

Effect of Replacing Alkyl Side Chains with Triethylene Glycols on Photovoltaic Properties of Easily Accessible Fluorene-Based Non-Fullerene Molecular Acceptors: Improve or Deteriorate?

Hydrophilic oligo(ethylene glycol) (OEG) side chains are more flexible than alkyl chains and can facilitate the π–π stacking of conjugated polymer backbones, which has been proven to be a key structural feature leading to better device performance in polymer:fullerene blend polymer solar cells (PSCs). So far, little has been known about the influence of OEG side chains on the performance of non-fullerene acceptors in polymer:non-fullerene acceptor blends. Based on an easily accessible conjugated backbone of dicyanomethylene indanone–thiophene–fluorene–thiophene–dicyanometnylene indanone (DICTF), two non-fullerene molecular acceptors were synthesized with decyl (DICTF-C10) and triethylene glycol monoether (DICTF-TEG) side chains to blend with the polymer donor of PTB7-Th for PSCs. Replacing the decyl side chains with the TEGs on DICTF does improve the π–π stacking between the conjugated backbones as expected. For DICTF-TEG, nevertheless, forming the BHJ blend with the PTB7-Th donor leads to unfavorable fil...

Major influence of the hydrophobic chain length in the formation of poly(3,4-propylenedioxypyrrole) (PProDOP) nanofibers with special wetting properties

Several species in nature have special wetting properties such as Lotus leaves or rose petals. Both the surface morphology and surface energy play a fundamental role. In particular, nanofibers were found to be exceptional surface structures due to a possible control in both water hydrophobicity and water adhesion as a function of their length, diameter, their orientation to the substrate or the spacing between them. Here, in the aim to prepare nanofibers with high liquid-repellent properties using conducting polymers, we have synthesized 3,4-propylenedioxypyrrole (ProDOP) derivatives with hydrocarbon and fluorocarbon chains in the 3-position, keeping the NH group free (important condition to lead to nanofibers thanks to hydrogen bonds). Different hydrocarbon and fluorocarbon chain lengths are studied. We obtain, for example, nanofibers of different size with octyl, decyl and C4F9 chains (intermediate hydrophobicity) with different liquid-repellent properties and liquid adhesion properties. More precisely, PProDOP-H8 is close to superhydrophobic properties (low water adhesion) while PProDOP-H10 is parahydrophobic (high water adhesion). This works could find many potential applications in the nanotechnology field as water harvesting surfaces, liquid separation membrane, and in anti-bioadhesion. Due to the presence of free NH groups, these materials could also be used as pH-sensitive materials while the nitrogen could also be easily functionalized.

Potent dialkyl substrate-product analogue inhibitors and inactivators of α-methylacyl-coenzyme A racemase from Mycobacterium tuberculosis by rational design

Rational approaches for the design of enzyme inhibitors furnish powerful strategies for developing pharmaceutical agents and tools for probing biological mechanisms. A new strategy for the development of gem-disubstituted substrate-product analogues as inhibitors of racemases and epimerases is elaborated using α-methylacyl-coenzyme A racemase from Mycobacterium tuberculosis (MtMCR) as a model enzyme. MtMCR catalyzes the epimerization at C2 of acyl-CoA substrates, a key step in the metabolism of branched-chain fatty acids. Moreover, the human enzyme is a potential target for the development of therapeutic agents directed against prostate cancer. We show that rationally designed, N,N-dialkylcarbamoyl-CoA substrate-product analogues inactivate MtMCR. Binding greatly exceeds that of the substrate, (S)-ibuprofenoyl-CoA, up to ∼250-fold and is proportional to the alkyl chain length (4–12 carbons) with the N,N-didecyl and N,N-didodecyl species having competitive inhibition constants with values of 1.9 ± 0.2 μM and 0.42 ± 0.04 μM, respectively. The presence of two decyl chains enhanced binding over a single decyl chain by ∼204-fold. Overall, the results reveal that gem-disubstituted substrate-product analogues can yield extremely potent inhibitors of an epimerase with a capacious active site.