Butyl Chain Research Articles

Vibrational sum–frequency generation spectroscopy of ionic liquid 1‐butyl‐3‐methylimidazolium tris(pentafluoroethyl)trifluorophosphate at the air–water interface

The structure and orientation of room temperature ionic liquid (RTIL) 1‐butyl‐3‐methylimidazolium tris(pentafluoroethyl)trifluorophosphate [PF3(C2F5)3], commonly known as [bmim][fap], have been investigated at the air−[bmim][fap] and air–water interfaces, employing vibrational sum–frequency generation (VSFG) spectroscopy. The VSFG spectra in the CH stretch region suggest presence of the [bmim] cation at the interfaces. Studies reveal that the butyl chain protrudes out into air, and the imidazolium ring lies almost planar to the interface. The CH stretch intensities get enhanced at the air–water interface, mainly because of polar orientation of imidazolium cation induced by interfacial water molecules. The OH stretch intensities are also enhanced at the air–water interface due to polar orientation of interfacial water molecules induced by [bmim][fap]. The Brewster angle microscopy suggests self aggregation of [bmim][fap] in the presence of water, and the aggregation becomes extensive showing dense surface domains with time. However, the surface pressure is almost unaffected due to aggregation.

Monte Carlo simulations of phase equilibria and microstructure of thiophene/[Bmim][PF6]/CO2

Monte Carlo simulations were carried out to calculate the phase behavior of thiophene in the binary and ternary mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) and carbon dioxide using a united atom model. The calculated pure ionic liquid densities and structural properties of [Bmim][PF6] as well as the vapor pressure of thiophene in the ionic liquid were compared with the available experimental data in the literatures, and a good agreement was obtained. Based on the radial distribution functions (RDFs) and spatial distribution functions (SDFs) results, thiophene molecules prefer to organize around the C10 atom of the butyl chain connected with the imidazolium ring. The concept of local composition in solutions was used to better understand the solution structure. It is shown that thiophene molecules can strongly associate with the cation. For the ternary system of CO2/thiophene/IL, CO2 can affect the solubility of thiophene in ionic liquid when the pressure is changed. CO2 molecules interact with the anion stronger than thiophene molecules. This implies that CO2 can be used as a potential recovery desorbent of thiophenic compounds in the ionic liquid by tuning the pressure.

Homo-Polymerization of 1-Hexene Catalysed by O^N^N (Salicylaldimine)Iron(III) Pre-Catalysts to Branched Poly(1-hexene)

Five new iron(III) 1-hexene polymerisation catalysts were prepared from the reactions of 2,4-di-tert-butyl-6-(2-(1H-imidazol-4-yl)ethylimino)methylphenol (L1), or 4-tert-butyl-6-(2-(1H-imidazol-4-yl)ethylimino)methylphenol (L2) or 2,4-di-tert-butyl-6-[(2-pyridin-2-yl-ethylimino)-methyl-phenol (L3) with anhydrous iron(II) halides to form [FeCl2(L1)] (1), [FeBr2(L1)] (2), [FeI2(L1)] (3), [FeBr2(L2)] (4) and [FeCl2(L3)] (5). All the iron(III) complexes 1–5 were activated with EtAlCl2 to produce active catalysts for the polymerisation of 1-hexene to low molecular weight poly(1-hexene) (Mn = 1021–1084 Da) and very narrow polydispersity indices (1.19–1.24). 1H and 13C{1H} NMR analysis showed the polymers are branched with methyl, butyl and longer chain branches. The longer chain branches are dominant indicating that 2,1-insertion of monomer is favoured over 1,2-insertion in the polymerisation reaction.

Formulation of pyridinium based RTIL-in-cyclohexane microemulsions: Investigations on size, conductivity and molecular interactions

Room-temperature ionic liquids (RTILs) based on alkyl pyridinium (py) and alkyl picolinium (pic) based structure are synthesized in combination with tetrafluoroborate (BF4−) anion [CnH2n+1py/pic][BF4], and further dispersed in cyclohexane using Triton X-100 (nonionic surfactant) as the emulsifier. The phase boundaries of the ternary system RTIL/TX-100/cyclohexane are investigated and microstructures in different regions of the phase diagram are identified by electrical conductivity measurements. At the onset corresponding to formation of RTIL-in-cyclohexane microemulsions, the required weight fraction of cyclohexane is higher for octyl substituted cations compared to their butyl counterpart. The electrical conductivity of the formed microemulsion increases gradually with a corresponding increase in temperature. Microemulsion of RTILs bearing butyl chain showed higher electrical conductivity compared to octyl substituted structures. The size and size distribution of the droplets in microemulsion were measured by dynamic light scattering (DLS), which revealed gradual increase in the droplet size with a corresponding increase in the RTIL/TX-100 mole ratio (R). The FTIR measurements confirmed strong H-bond formation between the pyridine hydrogen and oxyethylene (OE) groups in TX-100, which provides structural stability to the formed microemulsion.

Vibrational characterization of α-aminophosphinic acid derivatives of pyridine: DFT, Raman and SERS spectroscopy studies

This paper shows Fourier-transform Raman (FT⬜RS) and surface-enhanced Raman spectroscopy (SERS) studies of three α-aminophosphinic acid derivatives of pyridine: [(butylamino)(pyridin-2-yl)methyl]phenylphosphinic acid (α-PyNH), [(butylamino)(pyridin-3-yl)methyl]phenylphosphinic acid (β-PyNH), and [(benzylamino)(pyridin-4-yl)methyl]phenylphosphinic acid (γ-PyNH) immobilized onto colloidal sol nanoparticles and electrochemically roughened surface of silver. The molecular geometries and vibrational wavenumbers were calculated based on density functional theory (DFT) at the B3LYP 6-311G(df,p) level of theory. Based on the comparison of the FT⬜RS experimental and theoretical vibrational bands with the SERS results the orientation of the α-aminophosphinic acid derivatives of pyridine onto two silver substrates was proposed. The changes in the adsorption process under the influence of the position of substituent in regard to the ring N atom (in α-, β-, and γ-positions, respectively) and modification of the substituent (replacement of the butyl chain by the phenyl ring of high affinity to silver (γ-PyNH)) were also discussed.

Barium Titanate Nanoparticles Formed by Chlorine-Free Ambient Condition Sol Process Using Tetrabutylammonium Hydroxide

Barium titanate (BaTiO3: BTO) nanoparticles (NPs) were synthesized by chlorine-free ambient condition sol (ACS) process using heat reflux at low temperature of 90°C. The size distribution and morphology of BTO NPs were investigated by varying the concentration of tetrabutylammonium hydroxide (TBAH). The crystalline size of BTO NPs was decreased with increasing the amount of TBAH capping agent (average size changes from 54.3 to 38.7 nm for 0 to 0.5 M TBAH in X-ray diffraction measurement). The particle size of BTO NPs was principally controlled by a synthetic control of butyl chain of TBAH and also a steric effect of excess amount of TBAH. The dielectric constant of BTO NPs was decreased from 152 to 144 at 1 MHz after an adoption of TBAH capping agent with almost uniform dielectric loss (<0.027). But the dielectric constant of BTO NPs synthesized with various molar ratio of TBAH (0.1, 0.3, and 0.5) did not show a distinguished decrease. At the particle size range in this experiment, the dielectric behavior of BTO NPs was found to be mainly dependent on the TBAH ligands at BTO NPs formed during capping process, not on the size of BTO NPs.

Interfacial and mechanical properties of epoxy composites containing carbon nanotubes grafted with alkyl chains of different length

Dispersion of the nano-fillers is important in the manufacture of high performance nanocomposites. Dispersion of silane treated CNT/epoxy composites was analyzed for various alkyl chain lengths. Difference in mobility of alkyl chains of different length affects the excluded free volume and repulsive forces. An optimal chain length was observed to impart maximum mechanical and impact properties. Differences in the dispersion of CNT due to alterations in alkyl chain lengths were determined using electrical resistance measurement. Spreading of CNT/epoxy rearranged the CF tow resulting in a change in electrical resistance ratio (CERR) and the differences in alkyl chain length effected CNT spreading. Dispersion and wetting conditions with different alkyl chain lengths resulted in changes in CERR, ILSS and other proprieties. The butyl chain length was optimal of the alkyl chain lengths studied. This is attributed to the butyl chains known good mobility and steric repulsion effects compared to longer alkyl chain lengths.

Optimization and synthesis of an 18F‐labeled dopamine D3 receptor ligand using [18F]fluorophenylazocarboxylic tert‐butylester

There is still no efficient fluorine-18-labeled dopamine D3 subtype selective receptor ligand for studies with positron emission tomography. We aim at improving the D3 selectivity and hydrophilicity of a candidate ligand by changing the substitution pattern to a 2,3-dichlorophenylpiperazine and hydroxylation of the butyl chain. The compound [(18) F]3 exhibited D3 affinity of Ki = 3.6 nM, increased subtype selectivity (Ki (D2 /D3 ) = 60), and low affinity to 5-HT1A and α1 receptors (Ki (5-HT1A /D3 ) = 34; Ki (α1 /D3 ) = 100). The two-step radiosynthesis was optimized for analog [(18) F]4 by reducing the necessary concentration of the precursor amine (57 mM), which reacted with [(18) F]fluorophenylazocarboxylic tert-butylester under basic conditions. The optimization of the base (Cs 2 CO3 , 23 mM) and the adjustment of reaction temperature led to the radiochemical yield of 63% after 5 min at 35°C. The optimized reaction conditions were transferred on to the synthesis of [(18) F]3 with an overall non-decay corrected yield of 8-12% in a specific activity of 32-102 GBq/µmol after a total synthesis time of 30-35 min. This provides a D 3 radioligand candidate with improved attributes concerning selectivity and radiosynthesis for further preclinical studies.

Intrinsic Structure of the Interface of Partially Miscible Fluids: An Application to Ionic Liquids

We investigate by means of Molecular Dynamics simulations how the intrinsic surface structure of liquid/liquid interfaces involving ionic liquids depends on the opposite phase of varying polarity. We study 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF6) and 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imid (BMIM NTf2). The opposite phase is either cyclohexane or water, but as a reference, IL–vacuum interfaces are also studied. We combine a distance-based cluster search algorithm with the ITIM intrinsic analyzing method to separate liquid phases showing non-negligible mutual miscibility and to identify atoms residing at the instantaneous surface. In contrast to the well structured surface of IL–vacuum systems, at liquid/liquid interfaces of ILs density correlations, ionic associations, and orientational preferences are all weakened, this effect being much more pronounced when the other species is water. In such systems we observe a drastic reduction in the presence of the cation at the surface and an increase of appearance of polar moieties (of both the cations and anions) leading to decreased apolar character of the interface. Furthermore, cations are mostly found to turn with their butyl chains toward the bulk while having their methyl groups sticking toward water. Anion–cation associations are reduced and partially replaced by water–anion and rarely also water–cation associations.

Nitric oxide releasing acridone carboxamide derivatives as reverters of doxorubicin resistance in MCF7/Dx cancer cells

A series of nitric oxide donating acridone derivatives are synthesized and evaluated for in vitro cytotoxic activity against different sensitive and resistant cancer cell lines MCF7/Wt, MCF7/Mr (BCRP overexpression) and MCF7/Dx (P-gp expression). The results showed that NO-donating acridones are potent against both the sensitive and resistant cells. Structure activity relationship indicate that the nitric oxide donating moiety connected through a butyl chain at N10 position as well as morpholino moiety linkage through an amide bridge on the acridone ring system at C-2 position, are required to exert a good cytotoxic effect. Further, good correlations were observed when cytotoxic properties were compared with in vitro nitric oxide release rate, nitric oxide donating group potentiated the cytotoxic effect of the acridone derivatives. Exogenous release of nitric oxide by NO donating acridones enhanced the accumulation of doxorubicin in MCF7/Dx cell lines when it was coadministered with doxorubicin, which inhibited the efflux process of doxorubicin. In summary, a nitric oxide donating group can potentiate the anti-MDR property of acridones.

Revisiting the crystallization of poly(2-alkyl-2-oxazoline)s

Poly(2-alkyl-2-oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (Tg) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt-recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 °C and PiPropOx between 90 and 150 °C show that PAOx can crystallize in bulk when enough time is given. The decrease of Tg and the corresponding increase in chain mobility at T > Tg with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 721–729

Effect of alkyl side-chain length on the photophysical, morphology and photoresponse properties of poly(3-alkylthiophene)

The effect of alkyl side-chain length on the photophysical, morphology and photoresponse properties of poly (3-alkylthiophene) (P3AT) has been investigated. Butyl, hexyl, octyl, decyl, and dodecyl side chains have been studied. In solution state, the average lifetime of poly (3-octylthiophene) (P3OT) is the shortest among P3AT solution owing to the strong intrachain interaction. The fluorescence lifetime of P3AT solution increases with the side-chain length increasing. A similar trend occurs in the P3AT films. This phenomenon illustrates conformation ‘memory’ property evolving from solution state to solid film. The four lifetimes represent different photophysical processes and have been systematically analyzed. The photodetector based on P3DDT is a suitable candidate for practical application owing to the fast, reversible photoresponse and photostability. The high performance of P3DDT-based photodetector is correlated to the optimized morphology and strong interchain interaction which promotes the exciton delocalization.

Preparation and characterization of nanoparticles made from amphiphilic mono and per-aminoalkyl-β-cyclodextrins

Abstract Aminoalkyl derivatives of β-cyclodextrin, in their neutral form are insoluble amphiphilic cyclodextrins that could be dispersed as nanoparticles in water. Such nanoparticles solubilize host molecules either in the non-polar medium in between the alkyl chains or in an environment of medium polarity inside the hydrophobic cavity of the cyclodextrins. This allows the solubilization of a wider range of molecules such as drugs, fragrances, aromas… than classical nanoparticles containing either oil or polymer. A series of such compounds either mono- or per-substituted at the C6 methylene of the β-CD primary rim with either short butyl chain or long dodecyl chain are obtained by chemical modification of native β-cyclodextrin with aminoalkyl groups. Their physicochemical properties and utilization for the manufacture of nanoparticles have been studied. The solubility assessed from direct microscopy observation and surface tension measurements were low; they were related to the hydrophobic character of the amphiphilic β-CDs, that is, the number and length of their alkyl chains. The monobutyl derivative adsorbs at the air–water interface as a monolayer whereas the most hydrophobic derivatives collapses into a 3-dimensional adsorbed layer. Stable nanoparticles were prepared by means of dispersion by ultrasound or by the nanoprecipitation method. Sonication yielded large and polydisperse nanoparticles of size larger than 500 nm; nanoprecipitation resulted in the formation of small nanoparticles with sizes in the range 100–200 nm with a narrow particle size distributions.

Crystal structure of natural phaeosphaeride A.

The asymmetric unit of the title compound, C15H23NO5, contains two independent mol­ecules. Phaeosphaeride A contains two primary sections, an alkyl chain consisting of five C atoms and a cyclic system consisting of fused five- and six-membered rings with attached substituents. In the crystal, the mol­ecules form layered structures. Nearly planar sheets, parallel to the (001) plane, form bilayers of two-dimensional hydrogen-bonded networks with the hy­droxy groups located on the inter­ior of the bilayer sheets. The network is constructed primarily of four O—H⋯O hydrogen bonds, which form a zigzag pattern in the (001) plane. The butyl chains inter­digitate with the butyl chains on adjacent sheets. The crystal was twinned by a twofold rotation about the c axis, with refined major–minor occupancy fractions of 0.718 (6):0.282 (6).

Synthesis of Aliphatic Poly(ether 1,2-glycerol carbonate)s via Copolymerization of CO2 with Glycidyl Ethers Using a Cobalt Salen Catalyst and Study of a Thermally Stable Solid Polymer Electrolyte.

The synthesis and characterization of linear poly(ether 1,2-glycerol carbonate)s derivatized with pendant butyl, octyl, or stearyl tethers are reported. The polymers are obtained via the ring-opening copolymerization of butyl, octyl, or stearic glycidyl ethers with carbon dioxide using the [rac-SalcyCoIIIDNP] catalyst bearing a quaternary ammonium salt. Synthesized polymers were characterized by 1H and 13C NMR spectroscopy, FT-IR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and rheometry. Polymers with controlled molecular weights in the range of 8970-31 900 g/mol were obtained with low polydispersities between 1.1 and 1.4. Thermal properties of the materials confirm amorphous structures of the polymers with butyl and octyl chains, with glass transition temperatures of -24 and -34 °C, respectively. The stearyl tether polymer exhibited a melting point of 55 °C. Additionally, the potential of poly(butyl ether 1,2-glycerol carbonate) as a thermally stable solid polymer electrolyte was investigated, and it exhibits temperature-dependent conductivity with values comparable to those of optimized PEO-based electrolytes.

Crystal structure of 1-butyl-2,3-di-methyl-imidazolium dicarba-7,8-nido-undeca-borate.

In the title mol­ecular salt, C9H17N2 +·C2H12B9 −, the carborane cage has a bridging B—H—B bond on the open B3C2 face. The butyl side chain of the cation adopts an extended conformation [C—C—C—C = 179.6 (1)°]. In the crystal, the imidazolium ring is almost coplanar with the open face of the carborane anion. The cations stack in the [010] direction and the dihedral angle between the imidazolium rings of adjacent cations is 68.45 (6)°. The butyl chains extend into the space between carborane anions.

分子動力学シミュレーションによる四級アンモニウム系イオン液体の表面構造の研究

The surface structure of the quaternary ammonium based ionic liquid, tributylmethylammonium bis(trifluoromethanesulfonyl)amide ([TBMA][C1C1N]), has been studied using molecular dynamics simulation. The atomic number density profiles reveal that the ionic multilayering structure is formed at the surface with a layer thickness of the ionic diameter (∼10 Å). At the surface of the ionic liquid, TBMA+ and C1C1N− are oriented with the butyl chains of TBMA+ and the CF3 group of C1C1N− protruding out of the ionic liquid phase, respectively. However, all the three butyl chains are rarely pointed to the vacuum simultaneously. C1C1N− tends to point the CF3 group to the vacuum more strongly than TBMA+ does the butyl chains. The C2 conformation of C1C1N− is more stable than the C1 conformation even in the first ionic layer on average, as in the bulk. However, in the outmost part of the first ionic layer, the stability of C1 exceeds that of C2.

Synthesis and Characterization of a Novel Phenolic Lipid for Use as Potential Lipophilic Antioxidant and as a Prodrug of Butyric Acid.

Ferulic acid was modified to produce a novel phenolipid containing butyl chains. Ferulic acid was esterified with butanol to produce butyl ferulate which was further dihydroxylated followed by esterification with butyric anhydride to produce the phenolipid containing butyric acid. IR, NMR and MS techniques confirmed the structure of the synthesized structured lipophilic phenolic compound. The synthesized compound was tested for in vitro antioxidant and antimicrobial activities. The produced phenolipid showed moderate antioxidant activity in DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging assay but in linoleic acid oxidation method, it exhibited good activity compared with the parent compound and the reference compounds. The prepared derivative could find applications as antioxidant in lipophilic systems and also as a potential prodrug of butyric acid. It also showed antibacterial effect against the four bacterial strains studied. The drug-likeness properties of the prepared molecule calculated were in the acceptable ranges according to Lipinski's rule of 5 and suggest that it has potential to cross the blood-brain barrier.

Liquid/liquid interface layering of 1-butanol and [bmim]PF6 ionic liquid: a nonlinear vibrational spectroscopy and molecular dynamics simulation study.

IR-visible sum-frequency generation (IV-SFG) vibrational spectroscopy and a molecular dynamics (MD) simulation were used to study the local layering order at the interface of 1-butanol-d9 and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6), a room-temperature ionic liquid (RTIL). The presence of a local non-polar layer at the interface of the two polar liquids was successfully demonstrated. In the SFG spectra of 1-butanol-d9, we observed significant reduction and enhancement in the strength of the CD3 symmetric stretching (r(+)) mode and the antisymmetric stretching (r(-)) mode peaks, respectively. The results can be well explained by the presence of an oppositely oriented quasi-bilayer structure of butanol molecules, where the bottom layer is strongly bound by hydrogen-bonding with the PF6(-) anion. MD simulations reveal that the hydrogen-bonding of butanol with the PF6(-) anion causes the preferential orientation of the butanols; the restriction on the rotational distribution of the terminal methyl group along their C3 axis enhances the r(-) mode. As for the [bmim](+) cations, the SFG spectra taken within the CH stretch region indicate that the butyl chain of [bmim](+) points away from the bulk RTIL phase to the butanol phase at the interface. Combining the SFG spectroscopy and MD simulation results, we propose an interfacial model structure of layering, in which the butyl chains of the butanol molecules form a non-polar interfacial layer with the butyl chains of the [bmim](+) cations at the interface.

TD-DFT assessment of the excited state intramolecular proton transfer in hydroxyphenylbenzimidazole (HBI) dyes.

Dyes undergoing excited state intramolecular proton transfer (ESIPT) received increasing attention during the last decades. If their unusual large Stokes shifts and sometimes dual-fluorescence signatures have paved the way toward new applications, the rapidity of ESIPT often prevents its investigation with sole experimental approaches, and theoretical simulations are often welcome, if necessary, to obtain a full rationalization of the observations. In the present paper, we evaluate both the absorption and the fluorescence spectra of, respectively, the enol and keto forms of a series of hydroxyphenylbenzimidazole (HBI) using a robust protocol based on Time-Dependent Density Functional Theory (TD-DFT). Optical spectra were obtained accounting for both vibronic and environmental effects. The aim of this work is therefore not to evaluate the radiationless pathway going through the twisted ESIPT structures, though excited-state reaction paths between enol and keto forms have been rationalized. First we have compared three dyes differing by the strength of the donor groups, and we have quantified the impact of the flexible butyl chain substituting the imidazole side. In accordance with experiments, we show that the presence of a dialkylamino auxochrome allows to tune the excited-state potential energy surface leading to a weaker tendency to ESIPT. This trend is rationalized in terms of both structural and electronic effects. Next, larger hydroxyphenyl-phenanthroimidazole (HPI) were considered to assess the impact of a stronger π-delocalization. 0-0 energies and vibrationally resolved spectra of the corresponding fluoroborate derivatives were studied as well. The dialkylamino auxochrome significantly decreases the 0-0 energies due to the presence of an important charge transfer character, while the addition of a BODIPY moiety induces a change of the emission signature now localized on the BODIPY side rather than on the NBO core.