Linear Alkyl Research Articles

Understanding Self-Assembly and the Stabilization of Liquid/Liquid Interfaces: The Importance of Ligand Tail Branching and Oil-Phase Solvation

HypothesisOrganophosphorus-based ligands represent a versatile set of solvent extraction reagents whose chemical makeup plays an important role in extraction mechanism. We hypothesize that the branching of the extractant hydrophobic tail and its oil-phase solvation affect the liquid/liquid interfacial structure. Understanding the structure mediated adsorption and interfacial ordering becomes key in designing ligands with enhanced selectivity and efficiency for targeted extractions. ExperimentWe employed vibrational sum frequency generation spectroscopy and interfacial tension measurements to extract thermodynamic adsorption energies, map interfacial ordering, and rationalize disparate behaviors of model di-(2-ethylhexyl) phosphoric acid and dioctyl phosphoric acid ligands at the hexadecane water interface. FindingsWith increased surface loading, ligands with branched hydrophobic tails formed stable interfaces at much lower concentrations than those observed for ligands with linear alkyl tails. The lack of an oil phase and associated solvation results in markedly different interfacial properties, and thus measurements made at air/liquid surfaces cannot be assumed to correlate with the processes occurring at buried liquid/liquid interfaces. We attribute these differences in the surface mediated self-assembly to key variations in hydrophobic interactions and tail solvation taking place in the oil phase demonstrating that interactions in both the polar and nonpolar phases are essential to understand self-assembly and function.

Predictive Study of the Influence of the Position of the Sulfonate Substituent on the Chemical Stability of Some Linear Alkylbenzene Sulfonate Isomers

Molecules from industrial formulations are used as palliative solutions in the treatment and reuse of industrial waste, with very encouraging results in developing countries. However, the lack of knowledge of the physicochemical properties of these molecules constitutes a major obstacle in the search for an effective solution. To contribute to the characterization of their physicochemical properties, twenty molecules of linear alkyl benzenesulphonate isomers of C10 and C13 homologs and their parent structures were the subject of this study. The stability and overall reactivity parameters such as the energy gap (.∆E), the chemical potential (μ), the electrophilic index (ω) as well as the molecular dipole moment (μD) are determined by the DFT method with the level B3LYP / 6-311G (d, p) / (water; IEFPCM). The results showed that the meta position of the sulfonate substituent increases overall stability and reactivity and decreases the solubility of the more stable 2C10, 4C10, 2C13 and 3C13 homologues of linear alkylbenzene sulfonates. The parent molecules (2mC10, 4mC10, 2mC13 and 3mC13) obtained more stable and less soluble are in favor of the effects observed in the treatment of industrial waste.

The Impact of Chiral Citronellyl‐Functionalization on Indolenine and Anilino Squaraine Thin Films

AbstractThe impact on chiral aggregation in solution processed and thermally annealed thin films of two indolenine and one anilino squaraines with chiral (S)‐citronellyl functionalization at the nitrogen of the squaraine backbone is investigated. A pseudo polymorphic crystal structure is obtained for one of the indolenine squaraines, but thin films of both compounds are basically non‐aggregated and truly isotropic as evidenced by spectroscopic ellipsometry. The anilino squaraine coalesces and readily aggregates to circular dichroic but discontinuous thin films. The extent of circular dichroism correlates with the morphology of the samples, which is quantified by Mueller matrix polarimetry in combination with atomic force microscopy. The shape of the CD spectra reinforces the hybrid Frenkel and charge‐transfer excitonic nature of the characteristic double hump signatures within unpolarized absorbance spectra of previously investigated non‐chiral anilino squaraines with linear alkyl chain functionalization. Such excitonic CD offers an additional design parameter for next‐generation opto‐electronic devices.

Histopathological effects of detergent, Linear Alkyl benzene sulphonate on hepatopancreas of freshwater prawn, Macrobrachium lamarrei (Crustacea-Decapoda)

Freshwater prawns, Macrobrachium lamarrei (Crustacea-Decapoda) were subjected to static subacute exposure (0.755 mg/l) of detergent, Linear Alkyl Benzene Sulphonate (LAS) (25% of 96h LC50) for 10,20 & 30 days. Hepatopancreas showed pronounced changes like vacuolization, hypertrophy, hyperplasia and degenerative changes leading to almost complete loss of histoarchitecture after 30 days exposure. Peculiar cell shedding in tubules was noticed after 10 day exposure while heavy increase in wandering cell population was recorded after 20 day exposure. R&B cells were found most effected throughout the hepatopancreas. Histopathological effects were found duration dependent. Underlying mechanism of detergent toxicity and role of histopathology as biomarker has been discussed.

Development of Dithieno[3,2-b:2′,3′-d]thiophene (DTT) Derivatives as Solution-Processable Small Molecular Semiconductors for Organic Thin Film Transistors

Novel solution-processable dithieno[3,2-d:2′,3′-d]thiophene (DTT) derivatives with alkylated thiophene or alkyl chain substituents, 2,6-bis(5-octylthiophen-2-yl)dithieno[3,2-b:2′,3′-d]thiophene (compound 1), 2,6-bis(5-(2-ethylhexyl)thiophen-2-yl)dithieno[3,2-b:2′,3′-d]thiophene (compound 2), and 2,6-dioctyldithieno[3,2-b:2′,3′-d]thiophene (compound 3), have been synthesized and employed as small molecular organic semiconductors for organic field-effect transistors (OFETs). All compounds exhibited good thermal stability over 290 °C, while different side groups of DTT compounds afforded different melting temperatures. The molecular orbital energy levels were experimentally and theoretically calculated, and their trend was almost the same. The developed compounds were employed as active layers for top-contact/bottom-gate OFETs with average charge carrier mobility as high as 0.10 cm2/Vs and current on/off ratio > 107 in ambient atmosphere. Notably, DTT derivative with linear alkyl chain (-octyl) substituents showed the best device performance. High device performance could be attributed to the large grains and continuous surface coverages as well as high film texture of the corresponding semiconductor films.

Ultrafast vibrational dynamics of a solute correlates with dynamics of the solvent.

Two-dimensional infrared (2D-IR) spectroscopy is used to measure the spectral dynamics of the metal carbonyl complex cyclopentadienyl manganese tricarbonyl (CMT) in a series of linear alkyl nitriles. 2D-IR spectroscopy provides direct readout of solvation dynamics through spectral diffusion, probing the decay of frequency correlation induced by fluctuations of the solvent environment. 2D-IR simultaneously monitors intramolecular vibrational energy redistribution (IVR) among excited vibrations, which can also be influenced by the solvent through the spectral density rather than the dynamical friction underlying solvation. Here, we report that the CMT vibrational probe reveals solvent dependences in both the spectral diffusion and the IVR time scales, where each slows with increased alkyl chain length. In order to assess the degree to which solute-solvent interactions can be correlated with bulk solvent properties, we compared our results with low-frequency dynamics obtained from optical Kerr effect (OKE) spectroscopy-performed by others-on the same nitrile solvent series. We find excellent correlation between our spectral diffusion results and the orientational dynamics time scales from OKE. We also find a correlation between our IVR time scales and the amplitudes of the low-frequency spectral densities evaluated at the 90-cm-1 energy difference, corresponding to the gap between the two strong vibrational modes of the carbonyl probe. 2D-IR and OKE provide complementary perspectives on condensed phase dynamics, and these findings provide experimental evidence that at least at the level of dynamical correlations, some aspects of a solute vibrational dynamics can be inferred from properties of the solvent.

Coupling in quantum dot molecular hetero-assemblies

The design of large-scale colloidal quantum dots (QDs) assemblies and the investigation of their interaction with their close environment are of great interest for improving QD-based optoelectronic devices' performances. Understanding the interaction mechanisms taking place when only a few QDs are assembled at a short interparticle distance is relevant to better promote the charge or energy transfer processes. Here, small hetero-assemblies formed of a few CdSe QDs of two different sizes, connected by alkyl dithiols, are fabricated in solution. The interparticle distance is tuned by varying the linear alkyl chain length of the bifunctional spacer from nanometer to sub-nanometer range. The crystallographic analysis highlights that the nearest surfaces involved in the linkage between the QDs are the (101) faces. The thorough spectroscopic investigation enables a sound rationalization of the coupling mechanism between the interacting nanoparticles, ranging from charge transfer/wavefunction delocalization to energy transfer, depending on their separation distance.

Investigating the impact of regiochemistry in ester functionalized polyfurans

AbstractIn this study, the impact of ester side group regiochemistry on electronic and conformational properties of regioregular polyfurans was explored. A derivative with alternating head‐to‐head and tail‐to‐tail orientation of the side groups was synthesized and compared with its head‐to‐tail analogue, and these were benchmarked against the related regioregular poly(3‐hexylfurans). The study revealed that alkyl ester side groups in a head‐to‐head orientation will create significant steric strain as compared with linear alkyl chains with identical regiochemistry. Though the head‐to‐head ester side groups lead to twisting along the polymer backbone, they also produce a protective effect against photodegradation in comparison with a poly(3‐hexylfuran). Altogether, the work highlights how side groups can impact conformational properties and stability of polyfurans.

Nanobioremediation: A sustainable approach towards the degradation of sodium dodecyl sulfate in the environment and simulated conditions.

Nanotechnology has gained huge importance in the field of environmental clean-up today. Due to their remarkable and unique properties, it has shown potential application for the remediation of several pesticides and textile dyes. Recently it has shown positive results for the remediation of sodium dodecyl sulfate (SDS). One of the highly exploited surfactants in detergent preparation is anionic surfactants. The SDS selected for the present study is an example of anionic linear alkyl sulfate. It is utilized extensively in industrial washing, which results in the high effluent level of this contaminant and ubiquitously toxic to the environment. The present review is based on the research depicting the adverse effects of SDS in general and possible strategies to minimizing its effects by bacterial degradation which are capable of exploiting the SDS as an only source of carbon. Moreover, it has also highlighted that how nanotechnology can play a role in the remediation of such recalcitrant pesticides.

Primary, secondary screening and evaluation of LAS degrading potential of soil bacteria isolated from Vidya Pratishthan’s college area

Inefficiency of use of soap in hard water popularized the use of anionic surfactants namely, branched alkylbenzene sulphonates (BAS) and Linear alkyl benzene sulphonates (LAS) in detergents. The low cost and superior solubility in hard water had made them popular and first choice of many household care-products. However, the disadvantage associated with their use was formation of stable foam over waterbodies which is detrimental for both the aquatic plants and animals. The current study involves primary and secondary screening of LAS degrading organisms and evaluates their potential. The three isolates screened isolate 1 can degrade LAS to the tune of 66% in 5 days, isolate 2 and isolate 3 degrade 72.16% and 68.25% respectively in 4 days.

All‐cis poly(p‐phenylene vinylene)s with high molar masses and fast photoisomerization rates obtained through stereoretentive ring‐opening metathesis polymerization of [2,2]paracyclophane dienes with various aryl substituents

AbstractPoly(p‐phenylene vinylene)s (PPVs) are some of the most widely studied conjugated polymers in academia and industry, but most production methods lack precise control over molar masses and alkene stereochemistry. These critical parameters have a large influence on processability, polymer morphology, and optical properties. Herein, we report the stereoretentive ring‐opening metathesis polymerization (ROMP) of [2.2]paracyclophane dienes bearing either a linear alkyl substituent or a branched alkoxy substituent to form all‐cis PPVs with great solubility in organic solvents. The introduction of 2‐ethylhexyloxy side‐chains permits the preparation of PPV with uncharacteristically high molar masses (up to 108.8 kg/mol) for a polymerization with living characteristics. Exposure to UV light (365 nm) rapidly induces isomerization of all‐cis alkenes leading to the formation of all‐trans PPV. This study proposes an attractive strategy to synthesize soluble all‐cis and all‐trans PPVs with tunable, high molar masses through careful design of the ROMP monomer.

Insights into the Intrinsic Factors Affecting the NIR Reflectance Based on Rylene Diimide Molecules.

A clear understanding of the relationships between molecular structure and NIR reflectance (700–2500 nm) behavior is important and highly desirable for developing appropriate NIR-reflective materials to combat NIR heat radiation from sunlight. In this research, three groups of imide-based compounds have been adopted to investigate the influence of the intrinsic molecular structures on the NIR-reflective properties. It is found out that for the compounds with alkyl groups, the NIR reflectance will increase as the degree of the conjugated backbone increases, especially for the reflectance from 1750 nm to 2500 nm. In addition, despite that the alkyl or amine groups deteriorate the NIR reflectance, the NIR reflectance varies within a certain interval and the isomers with branched alkyl groups show identical or smaller NIR reflectance than those of isomers with linear alkyl groups. For different compounds, crystallinity seems to almost have no relationship with their NIR reflectance.

Ordered hexagonal columnar liquid crystalline self-assembly of mesogen-free sulfonylated side-chain chiral polyethers and their high dielectric property

To achieve large spontaneous polarization for ferroelectric liquid crystalline polymers, we have designed a series of mesogen-free isotactic polyethers with sulfonylated side chains. Different from prior studies using linear alkyl side chains, in this work a methyl branch was implemented in the alkyl side chains of the chiral polyethers. As a result of the continuous twist from the methyl branches and strong dipole-dipole interactions among neighboring sulfonyl groups, a helical chain conformation with tilted side chains was achieved. When the branched side chains were short (e.g., C5) and double chirality existed in both the main chain and side chains, a crystalline structure was obtained. When the branched side chains were long (e.g., ≥ C8) and single chirality existed in the main chain, an ordered hexagonal columnar liquid crystalline phase was induced. Their high-field dielectric property was studied by electric displacement-electric field (D-E) loop tests; however, no ferroelectric behavior was observed up to 200 MV/m. It was considered that the dipole-dipole interaction among neighboring sulfonyl groups in the helical chains was too strong to allow easy ferroelectric flipping.

Recent Advances in Molecular Design of Organic Thermoelectric Materials

Recent Advances in Molecular Design of Organic Thermoelectric Materials

Investigation of the temperature responsive behaviors of novel polyaspartamide derivatives bearing alkyl ether-type pendants

Previous works reported that some temperature responsive polyaspartamide derivatives exhibited pH responsiveness, although pH responsive functional groups or pH-cleavable linkages were not introduced during the preparing process, which may be related to the hydroxyl groups of their pendant alkanolamide moieties. In order to investigate whether pH will also affect the temperature responsive behavior of temperature responsive polyaspartamide derivatives without hydroxyl groups, four linear alkyl ether-type amine compounds with one ether oxygen atom and 3 to 6 carbon atoms, denoted as OCx (x represents the number of carbon atoms in alkyl ether-type amine compounds), were selected for the aminolysis reaction of poly(succinimide) to design and synthesize the polyaspartamide derivatives bearing alkyl ether pendants, named PASP-OCx. The chemical structures and molecular weights of the obtained polymers were characterized and confirmed by FTIR, 1 H NMR and SEC-MALLS. The water-solubilities, surface tensions and transmittances of PASP-OCx aqueous solutions were also investigated. Results showed that PASP-OCx can be dissolved in deionized water when x is less than or equal to 5. The surface tensions of PASP-OC4 and PASP-OC5 solutions exhibited obvious turning points. Interestingly, transmittances results showed that PASP-OC5 exhibited temperature responsive behaviors under acidic, neutral or alkaline conditions (pH ≤ 10.0); PASP-OC4 only exhibited temperature responsive behaviors under acidic condition (pH ≤ 3.0); while PASP-OC3 did not exhibit temperature responsive behavior. The LCST value of PASP-OC5 and PASP-OC4 can be turned by adjusting the pH value of their solutions, and decreases with decreasing the pH value. Additionally, the influence of pH on the LCST values of PASP-OC4 and PASP-OC5 was investigated by zeta potential, and the results showed that the decrease of LCST values may be due to the reducing of electrostatic repulsion with pH decreasing. Therefore, results showed that pH can also affect the temperature responsive behavior of temperature-responsive polyaspartamide derivatives that do not contain hydroxyl groups.

The effect of C12E6 nonionic surfactant on the solubilization of Eosin Y in unmodified- and hydrophobically modified poly(Acrylic acid) solutions

The effect of the hexaethylene glycol mono-dodecyl ether (C12E6) on the solubilization of Eosin Yellow (2,4,5,7-tetrabromofluorescein, disodium salt) in 0.1 % wt. solution of unmodified and hydrophobically modified poly(acrylic acid) (PAA) was investigated by steady-state and dynamic fluorescence. To this end, firstly the poly(acrylic acid) was hydrophobically modified with 3 % mol and, respectively, 10 % mol linear C16 alkyl chain graft. The behavior of the obtained polymers and that of the parent one in the appropriate solvents were investigated by several methods. It was revealed that the grafts associated with the formation of intra-coil hydrophobic nano-domains and that the polyacrylic acids had lower viscosity than their sodium polyacrylates counterparts, although the c*s were almost similar. The effect of C12E6 nonionic surfactant on 0.1 % wt. polymers solution was also investigated. In water, the addition of C12E6 to polyacid solution leaded to the decrease of the critical aggregation concentration (CAC or T1). On the contrary, in the water–ethanol mixture the interaction was delayed, thus the CAC increased. At the addition of Eosin Y to the surfactant or surfactant-polymer solutions, the dye interacted with each species present in the system, no matter the solvent was. It was also shown that, at higher surfactant concentration, the dye solubilized into bound or free micelles. Therefore, it was considered the nonionic surfactant helped the anionic dye Eosin Y to be incorporated in poly(acrylic acid) based polymers.

Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters

The conformational preferences of the ester group have the potential to facilitate the large amplitude folding of long alkyl chains in the gas phase. They are monitored by Raman spectroscopy in supersonic jet expansions for the model system methyl butanoate, after establishing a quantitative relationship with quantum–chemical predictions for methyl methanoate. This requires a careful analysis of experimental details, and a simulation of the rovibrational contours for near-symmetric top molecules. The technique is shown to be complementary to microwave spectroscopy in quantifying coexisting conformations. It confirms that a chain segment can be collapsed into a single all-trans conformation by collisional cooling, whereas alkyl chain isomerism beyond this five-membered chain largely survives the jet expansion. This sets the stage for the investigation of linear alkyl alkanoates in terms of dispersion-induced stretched-chain to hairpin transitions by Raman spectroscopy.

Long-chain ligand design in creating magnetic nano adsorbents for separation of REE from LTM

A series of magnetic adsorbents was created by grafting selected functional ligands directly on the surface of iron oxide nanoparticles (NP). The produced materials were characterized by SEM-EDS, TEM, AFM, FTIR, XRD, Mössbauer spectroscopy, low temperature gas sorption, and in relation to functional properties. Each of the applied ligands carried two functional groups including phosphonic acid involved in grafting, and either alcohol, thiol, amino, carboxylic- or phosphonic acid. The kinetics and thermodynamics of metal cation adsorption were investigated for Rare Earth (REE, Sm3+, Nd3+, Dy3+ and Tb3+) and Late Transition Metals (LTM, Co2+ and Ni2+) as representative for the content of magnetic materials, requiring recycling. Long linear alkyl chain (C10-C12) and, in case of phosphonic acid, even a shorter one (C6), were used to trace potential stabilization of the particles against iron leaching on desorption of adsorbed cations in acidic medium. The NP demonstrated high adsorption capacity, efficient desorption and considerable selectivity in separation of REE from LTM. Modification with ligands offers appreciable protection of magnetic particles against iron leaching.

Subgel-phase formation of membranes of ether-linked phosphatidylcholines

The formation of subgel (so-called hydrated crystal) phase of membranes of ether-linked phospholipids, dialkylphosphatidylcholines containing linear saturated alkyl chain (Cn = 14, 16 and 18), was examined under atmospheric and high pressure. The results of differential scanning calorimetry in 50 wt% aqueous ethylene glycol solution and water showed that these PC membranes undergo the subtransition from the subgel phase to the gel phase at a low temperature with or without the thermal pretreatment of lipid samples called annealing. The subtransition in water was clearly observed by light-transmittance measurements under high pressure and the transition temperature increased by applying pressure. The temperature-pressure phase diagrams and the thermodynamic quantities of the subtransition were obtained from the phase-transition data and compared with those of membranes of ester-linked phospholipids, diacylphosphatidylcholines. The phase diagrams indicated that all gel phases of the ether-linked PC membranes exist as stable phases while parts of the gel phases of the ester-linked PC membranes are metastable. The subtransition temperatures of the ether-linked PC membranes were lower than those of the ester-linked PC membranes by more than 10 °C and the corresponding thermodynamic quantities were extremely small. Further, it was revealed by high-pressure fluorometry that the difference in subgel phase between ether- and ester-linked PC membranes results from their phase structures: the nonbilayer interdigitated structure is maintained after the conversion from the gel phase to the subgel phase in the ether-linked PC membranes whereas the ester-linked PC membranes form the bilayer subgel phase with staggered structure.

Direct, Catalytic α-Alkylation of N-Heterocycles by Hydroaminoalkylation: Substrate Effects for Regiodivergent Product Formation.

Saturated N-heterocycles are prevalent in pharmaceutical and agrochemical industries, yet remain challenging to catalytically alkylate. Most strategies for C-H activation of these challenging substrates use protected amines or high loadings of precious metal catalysts. We report an early transition-metal system for the broad, robust, and direct alkylation of unprotected amine heterocycles with simple alkenes. Short reaction times are achieved using an in situ generated tantalum catalyst that avoids the use of bases, excess substrate, or additives. In most cases, this catalyst system is selective for the branched reaction product, including examples of products that are generated with excellent diastereoselectivity. Alkene electronic properties can be exploited for substrate-modified regioselectivity to access the alternative linear amine alkylation product with a group 5 catalyst. This method allows for the facile isolation of unprotected N-heterocyclic products, as useful substrates for further reactivity.