Alkyl Side Chain Length Research Articles

Synthesis and comparative studies on the surface-active and biological properties of linear poly(glycidol) esters

• Linear poly(glycidol) esters were synthesized as novel nonionic surfactants. • Physical and biological evaluations were conducted to establish a structure–property profile. • Length of alkyl side chains revealed significant impact on the functional performance. Herein, a series of linear poly(glycidol) esters were synthesized as novel nonionic surfactants. Their surface activities, emulsifying capacities, thermal stabilities as well as hemolytic activities were comprehensively investigated to establish a structure–property profile, which clearly revealed the impact of different lengths of alkyl side chains on the associated functional performance. Therefore, our study offered a valuable reference for their potential practical applications.

Poly(carbazole-co-1,4-dimethoxybenzene): Synthesis, Electrochemiluminescence Performance, and Application in Detection of Fe3+

In this study, four polycarbazole derivatives (PCMB-Ds) with different alkyl side chains were designed and synthesized via Wittig–Horner reaction. A novel solid-phase electrochemiluminescence (ECL) system was prepared by immobilizing PCMB-D on an indium tin oxide (ITO) electrode with polyvinylidene fluoride (PVDF) in the presence of tripropylamine (TPrA). It could be found that the increase in alkyl side chain length had little effect on the ECL signal of PCMB-D, while the increase in the degree of polymerization (DP) greatly enhanced the ECL signal. Furthermore, the P-3/ITO ECL sensor based on the polyoctylcarbazole derivative (P-3) with the best ECL performance was successfully constructed and detected Fe3+ under the optimal experimental conditions. The ECL signal steadily diminished with the increased concentration of Fe3+ because of the competition and complexation between Fe3+ and P-3 under the condition of pH 7.4. This P-3/ITO platform could realize a highly sensitive and selective detection of Fe3+ with a wide detection range (from 6 × 10−8 mol/L to 1 × 10−5 mol/L) and low detection limit of 2 × 10−8 mol/L, which could allow the detection of Fe3+ in multiple scenarios, and would have a great application prospect.

Effect of Alkyl Side Chain Length on the Lithium-Ion Conductivity for Polyether Electrolytes.

The design guidelines of polymer structure to effectively promote lithium-ion conduction within the polymer electrolytes (PEs) are crucial for its practical use. In this study, the electrolyte properties of a simple polyether having alkyl side chains with varied lengths (−(CH2)m−H, m = 1, 2, 4, 6, 8, and 12) were compared and established a valid design strategy based on the properties of the alkyl side chain. Various spectro-electrochemical measurements successfully connected the electrolyte properties and the alkyl side chain length. Steric hindrance of the alkyl side chain effectively suppressed the interaction between ether oxygen and lithium-ion (m ≥ 2), decreasing the glass transition temperature and the activation energy of lithium-ion transfer at the electrode-electrolyte interface. The strong hydrophobic interactions aligned and/or aggregated the extended alkyl group (m ≥ 8), creating a rapid lithium-ion transport pathway and enhancing lithium-ion conductivity. A clear trend was observed for the following three crucial factors determining bulk lithium-ion transport properties along with the extension of the alkyl side chain: 1) salt dissociability decreased due to the non-polarity of the alkyl side chain, 2) segmental mobility of polymer chains increased due to the internal plasticizing effect, and 3) lithium-ion transference number increased due to the inhibition of the bulky anion transport by its steric hindrance. The highest lithium-ion conductivity was confirmed for the PEs with an alkyl side chain of moderate length (m = 4) at 70°C, indicating the optimized balance between salt dissociability, polymer segmental mobility, and selective lithium-ion transfer. The length of an alkyl side chain can thus be a critical factor in improving the performance of PEs, including thermal stability and lithium-ion conductivity. Precise tuning of the alkyl side chain-related parameters such as steric hindrance, polarity, internal plasticizing effect, and self-alignment optimizes the polymer segmental mobility and salt dissociability, which is crucial for realizing high lithium-ion conductivity for PEs.

Anion Exchange Membranes for Fuel Cells Based on Quaternized Polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene Triblock Copolymers with Spacer-Sidechain Design.

This work studied the polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymers functionalized by butyl quaternary ammonium (C4Q) groups and alkyl side chains of different chain lengths (Cn, n = 0 to 24). The hydrated membrane morphology was modeled by dissipative particle dynamics simulation at hydration levels from 10 to 30. A hydroxide model was devised to characterize the diffusivity of anions under the coarse-grained framework. In general, the ionomers with alkyl side chains provided ion conductivity of a similar level at a lower ion exchange capacity. All hydrated SEBS–C4Q–Cn ionomers showed clear phase separation of the hydrophobic and hydrophilic domains, featuring 18.6 mS/cm to 36.8 mS/cm ion conductivity. The hydrophilic channels expanded as the water content increased, forming more effective ion conductive pathways. Introducing excess alkyl side chains enhanced the nano-segregation, leading to more ordered structures and longer correlation lengths of the aqueous phase. The membrane morphology was controlled by the length of alkyl side-chains as well as their tethering positions. Ionomers with functionalized side chains tethered on the same block resulted in well-connective water networks and higher conductivities. The detailed structural analysis provides synthesis guidelines to fabricate anion exchange membranes with improved performances.

Overcoming efficiency loss of large-area all-polymer solar cells via asymmetric alkyl side-chain engineering of naphthalene diimide-based n-type polymer

All-polymer solar cells (all-PSCs) are considered to be the priority in the commercialization process of organic photovoltaics due to their excellent stability. However, it faces the key challenge of device area enlargement leading to degradation of photovoltaic performance because of the significantly different shear forces at center and edges of the substrate. In this work, we designed and synthesized a NDI-based n-type polymer P(NDIHDDT-T2) with asymmetric alkyl side-chain to overcome this key challenge. All-PSCs based on P(NDIHDDT-T2) showed impressive high power conversion efficiency (PCE) of 11.2% for 0.04 cm2 device and 10.4% (reduced by about 7%) for 1 cm2 device, respectively, both of which outperformed the 10.7% for 0.04 cm2 device and 9.1% (reduced by about 15%) for 1 cm2 all-PSCs based on P(NDI2OD-T2). To the best of our knowledge, this is the highest PCE achieved for 1 cm2 NDI-based all-PSCs. We analyzed the interrelationship between the lengths of alkyl side-chain, crystalline and aggregation behavior, and photovoltaic performance of 1 cm2 device, which proved the advance of asymmetric alkyl side-chain engineering for constructing high-performance large-area all-PSCs, and may promote the commercialization process of all-PSCs.

Unfolding the cocrystallization–charge transport correlation in all-conjugated triblock copolymers via meticulous molecular engineering for organic field-effect transistors

The ability to render the cocrystallization over microphase separation in all-conjugated block copolymers represents an important endeavor towards achieving enhanced charge transport. This, however, remains a grand challenge, particularly in all-conjugated triblock copolymers. Herein, we report the unravelling of the dependence of cocrystallization in all-conjugated triblock copolymers on a set of internal structural parameters, and more importantly, the scrutiny of the correlation of their unique cocrystalline structures to charge transport properties for organic field-effect transistors (OFETs). Specifically, a series of poly(3-butylthiophene)-block-poly(3-alkylthiophene)-block-poly(3-hexylselenophene) triblock copolymers (denoted P3BT-b-P3AT-b-P3HS) are meticulously designed and synthesized. Intriguingly, a shorter alkyl side chain length and a shorter main chain length of the central P3AT, as well as a stronger cocrystallization ability of the two outer blocks (P3BT and P3HS), are found to favor the cocrystallization of the three dissimilar blocks in P3BT-b-P3AT-b-P3HS. Notably, the charge transport properties of P3BT-b-P3AT-b-P3HS correlate strongly to their various crystalline structures, thereby imparting their utility for high-performance OFETs. This study highlights the robustness of meticulous molecular engineering of all-conjugated multiblock copolymers in tailoring their cocrystallization behavior and in turn charge transport characteristics that underpins their advances in optoelectronic materials and devices.

Influence of side-chain length on antifungal efficacy of N-alkyl nicotinamide-based compounds.

This article presents fungicidal properties of 9 synthesized nicotinamide-bromides with different alkyl side chain lengths toward Fusarium graminearum, Sclerotinia sclerotiorum, and Botrytis cinerea which were examined. The fungicidal properties were determined by the measurement of the radial growth of fungi, followed by the calculation of the antifungal index. The obtained results were correlated with the descriptors from DFT calculations to determine structural features that affect the fungicidal properties of nicotinamides. Based on the experimental and theoretical results, it was confirmed that F. graminearum is most resistant to the change of lipophilicity of compounds, while S. sclerotiorum is most sensitive. For all investigated compounds, the growth rate decreased with the increase of carbon atoms in the side chain until tetradecylnicotinamidium bromide, [C14Nic][Br], while the further prolongation of the alkyl side chain increased the growth rate of fungus. This behavior was explained by the distinguished hydrophobic and hydrophilic surfaces in [C14Nic][Br] due to interactions between keto oxygen and bromide anion absent in the case of nicotinamides with a longer chain.

Mechanofluorochromic Difluoroboron β-Diketonates Based Polymer Composites: Toward Multi-Stimuli Responsive Mechanical Stress Probes.

Developing mechano-responsive fluorescent polymers that exhibit distinct responses to distinct mechanical stresses requires a careful design of the fluorophore in order to tune its interactions with the polymer. A series of mechanofluorochromic (MFC) polymer composites are prepared by dispersing difluoroboron diketonates complexes with various alkyl side-chain lengths (DFB-alkyl) in linear low-density polyethylene. Observation of the resulting polymer composites under a microscope reveals different aggregate sizes of the three DFB-alkyls, thus confirming the functionalization by alkyl side chains as a powerful approach to control the aggregation process in a polymer. Besides, the three polymer composite samples are shown to be sensitive to both stretching and scratching, thereby consisting in the first reported example of MFC polymer responding to these two distinct mechanical stimuli. To establish a structure-property relationship, the strategy consisted in applying controlled tensile or friction forces while simultaneously monitoring fluorescence changes. Interestingly, the intensity of the MFC response to both stretching and scratching depends on the alkyl chain length and thus on the aggregation properties of the fluorophore. According to a time-resolved fluorescence study, the emission is found to originate from different species following the type of applied stress (tensile or friction force).

Multiscale Structure of Poly(ionic liquid)s in Bulk and Solutions by Small-Angle Neutron Scattering

Poly(ionic liquid)s (PILs), similar to their ionic liquid (IL) analogues, present a nanostructure arising from local interactions. The influence of this nanostructure on the macromolecular conformation of polymer chains is investigated for the first time by means of an extensive use of small angle neutron scattering on a series of poly(1-vinyl-3-alkylimidazolium)s with varying alkyl side-chain length and counter-anion both in bulk and in dilute solutions. Radii of gyration are found to increase with the side-chain length in solution as a consequence of crowding interactions between neighboring monomers. In bulk, however, a non monotonic evolution of the radius of gyration reflects a change in chain flexibility and a potential screening of electrostatic interactions. Additionally at smaller scale, SANS provides an experimental estimation of both the chain diameter and the correlation length between neighboring chains, comparison of which unveils clear evidence of interdigitation of the alkyl side-chains. These structural features bring precious insights in the understanding of the dynamic properties of PILs.

Prooxidative effect of cardols is involved in their cytotoxic activity against murine B16–F10 melanoma cells

Cardols are resorcinolic lipids, available in many natural sources including cashew nut, pistachio, macadamia, and mango. Despite of several beneficial biological activities of cardols, cytotoxic activities of cardols are not fully understood. In preliminary studies, 5[8(Z),11(Z),14-pentadecatrienyl]resorcinol, known as cardol (C15:3) was found to inhibit tyrosinase-catalyzed melanin formation in cell-free system. In the case of cultured cell analysis, cardol (C15:3) showed intense cytotoxicity but not anti-melanogenic activity against B16–F10 melanoma cells. Subsequently, cardol (C10:0) and cardol (C5:0), containing shorter alkyl side chain, exhibited inferior cytotoxicity compared to cardol (C15:3). The cytotoxicity via cardol (C15:3) was reversed by the addition of antioxidants, indicating that intracellular prooxidative activity was involved. Furthermore, cardol (C15:3) produced significant levels of reactive oxygen species (ROS) while cardol (C5:0) generated lesser ROS levels. Our findings suggest the cytotoxic activity of cardols is their prooxidative effect depending on the length of alkyl side chain.

Acid enrichment via electrodialyser fabricated with poly(vinyl chloride)-based anion exchange membrane: Effect of hydrophobicity of aliphatic side-chains tethered on imidazolium groups

Electrodialysis (ED) technology equipped with proton blocking anion exchange membranes (AEMs) has great potential applications in recovering acidic wastewater. To develop high performance proton-blocking AEMs, in this work, a series of imidazolium functionalized poly(vinyl chloride) (PVC) AEMs are designed. In particular, the length of alkyl side chains tethered on the imidazole compound is optimized to adjust the micro-structure of AEM. Our research demonstrates that the density of 1-butylimidazole functionalized PVC AEM matrix is enhanced, which has been proved by water uptake and thermogravimetric analysis. Hence, the acid blocking performance of optimized AEM (PVC-Im-4C) is strengthened. The maximum concentration of H+ in concentrate chamber of electrodialyser enriched by the PVC-Im-4C AEM is 1.81 M through the 24 h ED process at a current density of 20 mA·cm−2 (the initial concentration of hydrogen ions: 1.0 M). The result suggests that the optimized PVC-Im-4C AEM with long alkyl side chain on imidazole shows the excellent capacity in acid enrichment. This work should provide guidance for the follow-up design of the advanced proton blocking AEMs.

CD36-Binding Amphiphilic Nanoparticles for Attenuation of Alpha Synuclein-Induced Microglial Activation.

Neuroinflammation is one of the hallmarks contributing to Parkinson's Disease (PD) pathology, where microglial activation occurs as one of the earliest events, triggered by extracellular alpha synuclein (aSYN) binding to the CD36 receptor. Here, CD36-binding nanoparticles (NPs) containing synthetic tartaric acid-based amphiphilic polymers (AMs) were rationally designed to inhibit this aSYN-CD36 binding. In silico docking revealed that four AMs with varying alkyl side chain lengths presented differential levels of CD36 binding affinity and that an optimal alkyl chain length would promote the strongest inhibitory activity towards aSYN-CD36 interactions. In vitro competitive binding assays indicated that the inhibitory activity of AM-based NPs plateaued at intermediate side chain lengths of 12- and 18-carbons, supporting the in silico docking predictions. These 12- and 18-carbon length AM NPs also had significantly stronger effects on reducing aSYN internalization and inhibiting the production of the proinflammatory molecules TNF-α and nitric oxide from aSYN-challenged microglia. All four NPs modulated the gene expression of aSYN-challenged microglia, downregulating the expression of the proinflammatory genes TNF, IL-6, and IL-1β, and upregulating the expression of the anti-inflammatory genes TGF-β and Arg1. Overall, this work represents a novel polymeric nanotechnology platform that can be used to modulate aSYN-induced microglial activation in PD.

A thermodynamic investigation of the effect of cationic structure on the self-aggregation behavior of Surface-Active ionic liquids in the presence of an amino acid

A series of imidazolium-based ionic liquids (ILs) with varying side alkyl chain length at N3 position which includes [C12mim][Br], [C12eim][Br], and [C12bim][Br] have been synthesized and characterized by 1H NMR. Then, their aggregation behavior in the presence of different concentrations of the amino acid L-Tryptophan (L-Trp) at different temperatures has been examined using conductometric, tensiometric, and UV–vis (absorption spectra) techniques. The critical micelle concentration (CMC) of ILs has been investigated in the absence and presence of amino acid to acquire a better understanding of the colloidal behavior of ILs in presence of amino acid as an external additive. The addition of amino acid is observed to reduce the CMC values of the ILs examined in an aqueous media. Likewise, applying a charged pseudo-phase model of micellization, the thermodynamic parameters of micellization, such as a change in standard free energy (ΔGmo), change in standard enthalpy (ΔHmo), and change in standard entropy (ΔSmo), have been scrutinized from the dependence of CMC on temperature. The surface tension approach was also used to evaluate interfacial characteristics. It was discovered that increasing the length of the side chain increases surface activity. All of the estimated parameters were utilized to determine the electrostatic and hydrophobic contributions of IL to the formation of micellar aggregates.

Properties of Bromine Fused Salts Based on Quaternary Ammonium Molecules and Their Relevance for Use in a Hydrogen Bromine Redox Flow Battery.

Bromine complexing agents (BCA) in aqueous electrolytes for hydrogen bromine flow batteries are used to reduce bromine‘s vapour pressure, while an insoluble and liquid fused salt is formed. The properties (concentrations, composition, conductivity and viscosity) of this fused salt are investigated in this study systematically ex situ by using 7 BCAs at different state of charge in HBr/Br2/H2O electrolytes with a theoretical capacity of 179.6 Ah L−1. Bromine is stored in the fused salt at concentrations up to 13.6 M, reaching theoretical volumetrical capacities up to 730 Ah L−1 in fused salts. The fused salt consists of a pure, bromine‐ and water‐free ionic liquid of organic [BCA]+ cations and polybromides, and its conductivity bases on a hopping mechanism among the polybromides. Alkyl side chain length of the BCAs and distribution of polybromides influence strongly the conductivity and viscosity of the fused salts. 1‐ethylpyridin‐1‐iumbromide results to be favoured BCA for application.

Analysis of Ethylene Copolymers with Long-Chain α-Olefins (1-Dodecene, 1-Tetradecene, 1-Hexadecene): A Transition between Main Chain Crystallization and Side Chain Crystallization.

A series of ethylene copolymers with long-chain α-olefins [LCAOs, 1-dodecene (DD), 1-tetradecene (TD), 1-hexadecene (HD)] and various LCAO contents were prepared, and their thermal properties, including effects of LCAO content and side chain length, were explored. The Cp*TiCl2(O-2,6-iPr2-4-SiEt3-C6H2)–MAO catalyst system afforded rather high-molecular-weight copolymers with unimodal molecular weight distributions and uniform compositions (confirmed by DSC thermograms). In addition to the melting temperatures (Tm values) corresponding to the so-called main chain crystallization (samples with low LCAO contents, the Tm value decreased upon increasing the LCAO content) and the side chain crystallization [polymer samples with high LCAO contents, by intermolecular interaction of side chains as observed in poly(DD), poly(TD), and poly(HD)], the other Tm value was observed, especially in poly(ethylene-co-HD)s (assumed to be due to co-crystallization of the branch and the main chain through an interaction of the main chain and the long side chains). The presence of another crystalline phase in poly(ethylene-co-HD)s was also suggested by a wide-angle X-ray diffraction (WAXD) analysis. These Tm values in poly(ethylene-co-TD)s and poly(ethylene-co-DD)s with rather high TD or DD contents were affected by the heating conditions in the measurement of DSC thermograms (5 or 10 °C/min), suggesting that the driving force for formation of the crystal packing (observed as Tm) is weak and affected by the alkyl side chain lengths.

Vibronic States and Edge-On Oriented π-Stacking in Poly(3-alkylthiophene) Thin Films

The influence of alkyl side-chain length [CnH2n+1 (A), where n = 6 (hexyl), 8 (octyl), 12 (dodecyl)] and thermal annealing (TA) and the definite roles of these in the quantity and quality of π-stacked crystallinity and edge-on orientated (EO) ordering of spin-coated poly(3-alkylthiophene) [P3AT] thin films, which are of massive significance in their optoelectronic properties, were investigated using complementary optical absorption spectroscopy and X-ray reflectivity (XR) techniques. The energy-band diagram, corresponding to the vibronic levels, obtained from the optical absorption spectrum provides information about the percentage, planarity, local order, and average conjugation length of the crystalline aggregates, while the electron density profile obtained from the XR provides unique information about the EO ordering and its variation along the depth. A prominent EO ordering near the substrate with a gradually decreased ordering toward the top surface is observed in each film. An as-cast P3HT film of shorter side-chain (having a natural nucleation tendency and rigidity) shows a slightly higher crystallinity and weaker excitonic coupling, while as-cast P3DDT film (having longer side-chain flexibility) shows a slightly better EO ordering. After the TA, the planarity of the unfolded backbone improves in each film; however, the effect is maximum in the P3DDT film. The EO ordering also improves throughout the film (by a thermal energy-induced reorientation of crystallites) but more toward the top surface (by increasing the decay length), preserving the exponential decay nature. The P3HT film (with the better initial crystallinity and planarity) shows an appreciable improvement, while the P3DDT film (where the crystallinity increases and crystallites have a better reorientational ability) shows the maximum improvement in the EO ordering. The improvement of the crystallinity (in quantity and quality) and the EO ordering of P3AT in thin films (as active layers), especially near the film–substrate interfaces, are of immense importance for their better in-plane charge carrier mobility in a thin-film transistor.

Influence of the alkyl side chain length on the room-temperature phosphorescence of organic copolymers

Pure organic room-temperature phosphorescence (RTP) materials have attracted wide attention owing to their excellent luminescent properties and great potential in various applications. In this work, iminostilbene and its analogues are applied to realize RTP emission by copolymerizing with acrylamide. It can be concluded that the growth of alkane chain in monomers can enhance the lifetime and photoluminescence quantum yield of RTP emission, and polymers with the larger conjugated structure of the monomer show a longer RTP emission wavelength. This work provides a series of new pure organic RTP materials and might provide new thoughts for designing more advanced and superior RTP materials.

DFT and COSMO-RS studies on dicationic ionic liquids (DILs) as potential candidates for CO2 capture: the effects of alkyl side chain length and symmetry in cations.

A few studies on CO2 capture using dicationic ionic liquids (DILs) show that they are more promising absorbents for CO2 capture than monocationic ILs (MILs). Ion-ion, ion-CO2 and DIL molecule-CO2 interactions are important for understanding the performance-structure-property relationships for the rational design of DILs for CO2 capture applications. However, the role of these interactions in determining CO2 solubility in DILs is unclear. In this study, we used DFT methods to understand these interactions in three selected DILs)considering the effects of alkyl side chain length and symmetry in cations (by exploring different aspects, such as the electronic and geometrical structures, topological properties and the strength and nature of interactions, charge transfer, etc. The results showed that the most suitable solvent for CO2 is the symmetric DIL with a longer side chain length, i.e. [Bis(mim)C5-(C4)2][NTf2]2. In addition, we used the COSMO-RS calculations to obtain the macroscopic solubility of CO2 in the studied DILs, which was in good agreement with the DFT results. Gas selectivity results calculated using COSMO-RS theory indicated that the selectivity of CO2 from H2, CO and CH4 gases decreases slightly with increasing the length of side alkyl chains.

Mononuclear nickel(ii) complexes as electrocatalysts in hydrogen evolution reactions: effects of alkyl side chain lengths

Three mononuclear Schiff-base–Ni(ii) complexes act as electrocatalyst for hydrogen evolution reaction using acetic acid and trifluoroacetic acid as the substrates. With the increase in chain length of ligand, efficiency of the catalyst decreases.

Interaction Types in C6H5(CH2)nOH-CO2 (n = 0-4) Determined by the Length of the Side Alkyl Chain.

C6H5(CH2)nOH-CO2 complexes have been investigated using rotational spectroscopy (n = 0-2) complemented by quantum chemical calculations (n = 0-4), which implies that the side alkyl chain length can determine the types of intermolecular interactions. Unlike the in-plane C···O tetrel bond in phenol-CO2, the π*CO2···πaromatic interaction has been shown to link CO2 to phenylmethanol and 2-phenylethanol, which is, to the best of our knowledge, the first time it has been demonstrated by rotational spectroscopy. Further elongations of the side alkyl chain gradually increase the energies of intramolecular hydrogen bonds in 3-phenylpropanol and 4-phenylbutanol so that CO2 cannot break it. CO2 will be pushed farther from the monomers and link with the -OH group through a dominating C···O tetrel bond. Our observations would allow, with the choice of the proper length of the side alkyl chain, new strategies for engineering C···πaromatic-centered noncovalent bonding schemes for the capture, utilization, and storage of CO2.