Alkyl Side Chains Research Articles

Effect of Alkyl Side Chain Length on Electrical Performance of Ion-Gel-Gated OFETs Based on Difluorobenzothiadiazole-Based D-A Copolymers

The performance of organic field-effect transistors (OFETs) is highly dependent on the dielectric–semiconductor interface, especially in ion-gel-gated OFETs, where a significantly high carrier density is induced at the interface at a low gate voltage. This study investigates how altering the alkyl side chain length of donor–acceptor (D-A) copolymers impacts the electrical performance of ion-gel-gated OFETs. Two difluorobenzothiadiazole-based D-A copolymers, PffBT4T-2OD and PffBT4T-2DT, are compared, where the latter features longer alkyl side chains. Although PffBT4T-2DT shows a 2.4-fold enhancement of charge mobility in the SiO2-gated OFETs compared to its counterpart due to higher crystallinity in the film, PffBT4T-2OD outperforms PffBT4T-2DT in the ion-gel-gated OFETs, manifested by an extraordinarily high mobility of 17.7 cm2/V s. The smoother surface morphology, as well as stronger interfacial interaction between the ion-gel dielectric and PffBT4T-2OD, enhances interfacial charge accumulation, which leads to higher mobility. Furthermore, PffBT4T-2OD is blended with a polymeric elastomer SEBS to achieve ion-gel-gated flexible OFETs. The blend devices exhibit high mobility of 8.6 cm2/V s and high stretchability, retaining 45% of initial mobility under 100% tensile strain. This study demonstrates the importance of optimizing the chain structure of polymer semiconductors and the semiconductor–dielectric interface to develop low-voltage and high-performance flexible OFETs for wearable electronics applications.

Improving the Uniformity and Stretchability of Inkjet-Printed Films by Adding the Surfactant Triton X.

Stretchable organic light-emitting diodes (OLEDs) are a key component of stretchable electronics. Inkjet printing is a potential processing method for stretchable and flexible OLEDs. However, improving the uniformity and stretchability of the emission layer (EML) prepared by inkjet printing is challenging. Here, we propose a strategy to simultaneously improve the uniformity and stretchability of inkjet-printed films by tuning the Marangoni flow and increasing the free volume. To verify our idea, Triton X (TX) with a lipophilic alkyl end and a hydrophilic hydroxyl end was added to the Super Yellow (SY)/polystyrene-block-polybutadiene-block-polystyrene (SBS) blend film. TX played two roles. (1) To inhibit the coffee ring effect. The surface tension of the solution decreased because the hydrophilic ends of TX repelled with the nonpolar solvent toluene to decrease the cohesion of toluene molecules on the surface. Thus, the surface tension at the edges was lower than in the middle due to the high evaporation rate at the edges during solvent evaporation. This resulted in the generation of the inward Marangoni flow to drive the solute toward the middle. Therefore, the coffee ring effect was inhibited, and a uniform film was formed. (2) To improve the stretchability. With TX, the glass transition temperature decreased because TX acted as a plasticizer to insert between the polymer chains due to the attraction between the lipophilic ends of TX and the alkyl side chains of SY. This provided more free volume for the polymer chains to move and orientate under strain, which is beneficial for the stretchability. Finally, we fabricated OLEDs with the inkjet-printed stretchable EML. At 100% strain, the luminance kept 70% of the initial luminance, much higher than that without the surfactant (33%).

Chemical Investigation of the Mediterranean Sponge Crambe crambe by UHPLC-HRMS/MS via Manual and Computational Dereplication Approaches.

The CH2Cl2-MeOH extract of the Mediterranean sponge Crambe crambe was investigated via UHPLC-HRMS/MS employing manual dereplication and in silico mass spectrometry tools. A deconvolution approach was implemented for the extensive metabolic characterization of the sample, resulting in the annotation of 53 compounds. The analysis of data-dependent HRMS/MS scans was conducted to establish fragmentation patterns characteristic of each crambescin A, B, and C sub-families. Among the 39 compounds identified from these groups, 22 analogues were reported for the first time including 4 new homologous series that differed by the ratio of methylene units in the upper (n + 2) and lower (m + 2) alkyl side chains. More specifically, crambescins presenting m = 5 or 6 and n = 5 (compounds 7, 11, 22 and 24) as well as m = 5 or 6 and n = 4 (compounds 5, 6, 8, 9, 12 and 14) were characterized. Additionally, four new features, potentially corresponding to new crambescidin analogues (compounds 13, 15, 35, and 39), were also reported. The identity of the dereplicated features was further validated by studying crambescins' spectral similarities through a feature-based molecular networking approach. Overall, this study suggests UHPLC-HRMS/MS-through the integration of manual and computational dereplication approaches-as a valuable tool for the investigation and high-throughput characterization of the C. crambe metabolome.

Y6-Derived Non-fullerene Acceptors with Unsaturated Alkyl Side Chains Enabling Improved Molecular Packing for Highly Efficient Additive-Free Organic Solar Cells

Y6-Derived Non-fullerene Acceptors with Unsaturated Alkyl Side Chains Enabling Improved Molecular Packing for Highly Efficient Additive-Free Organic Solar Cells

Investigation of the mechanism of [M-H]+ ion formation in photoionized N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione derivatives during higher order MSn high-resolution mass spectrometry.

The mechanism underlying dopant-assisted atmospheric pressure photoionization's (APPI) formation of ions is unclear and still under debate for many chemical classes. In this study, we reexamined the gas-phase reaction mechanisms responsible for the generation of [M-H]+ precursor ions, resulting from the loss of a single hydrogen atom, in a series of N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione (TPD) derivatives. Atmospheric pressure photoionization combined with higher order MS/MSn using high-resolution mass spectrometry (APPI-HR-CID-MSn) and electronic structure calculations using density functional theory were used to determine the chemical structure of observed [M-H]+ ions. As a result, the higher order MSn (n = 3) experiments revealed a reversed Diels-Alder fragmentation mechanism, leading to a common fragment ion at m/z 322 from the studied [M1-5-H]+ ion species. In addition, the calculation for two chemical structure models (N-alkyl-TPD1 and N-alkyl-TPD5) showed that the fragment structure, resulting from the removal of the hydrogen atom connected to the third carbon atom of the N-alkyl side chain, has a more stable cyclic form compared with the linear one. The proposed chemical structure of the N-alkyl TPD ion species, following the loss of a single hydrogen atom, was revealed during APPI-HR-CID-MSn (n= 3) experiments on the [M-H]+ species. Hydrogen radical (H•) abstraction from the alkyl side chain (e.g., hexyl, heptyl, octyl, 2-ethylhexyl, and nonyl) triggered a rearrangement in the radical cation structure of the N-alkyl-TPD derivatives, initiating cyclization and forming a six-membered ring that connects the oxygen atom to the third carbon atom in the alkyl chain. In addition, theoretical calculations supported the APPI-HR-CID-MSn (n = 3) experiments by demonstrating that the proposed chemical structure, resulting from the intramolecular cyclization of the N-alkyl-TPD ion species, was stable in the presence of chlorobenzene. These findings will aid the structural determination and elucidation of molecules with similar core structures.

Precision Fluorine Functionalization in Alkyl Side Chains of Polymer Donors for Highly Efficient Organic Solar Cells

Precision Fluorine Functionalization in Alkyl Side Chains of Polymer Donors for Highly Efficient Organic Solar Cells

Surface-induced nano-generator utilizing a thermo-responsive smart window based on ionic liquid aqueous solution that exhibits lower critical solution temperature type phase separation

We demonstrate a surface-induced nano-generator utilizing a thermo-responsive smart window based on ionic liquid aqueous solution that exhibits lower critical solution temperature (LCST) type phase separation. This smart window was fabricated by filling an aqueous solution of [nBu4P][CF3COO] between the glass substrates coated with two different polymers: a polyimide with an alkyl side chain and an amorphous fluoropolymer. Below the LCST, the transmittance of the smart window was 87 %, nearly identical to that of a glass substrate. In contrast, when heated above the LCST, the [nBu4P][CF3COO] aqueous solution undergoes phase separation, causing the [nBu4P] cations and [CF3COO] anions to adsorb onto the polyimide with the alkyl side chain and the amorphous fluoropolymer facilitated by the surface pinning effect. This adsorption process results in the smart window generating electricity while transitioning to an opaque state. Therefore, the proposed smart window functions as an electricity-generating thermo-responsive device that can switch between transparent and opaque states in response to temperature changes.

Lithium-ion batteries pitch-based carbon anode materials: The role of molecular structures of pitches

To understand the effect of molecular configurations of coal tar pitch (CTP) on the reaction mechanism of carbonization and Li storage performance of subsequent carbonized products, four CTPs with different molecular structures are treated by liquid and solid phase carbonization and then tested the electrochemical performance of their carbonized products as anode materials for Lithium-ion batteries (LIBs). The results reveal that CTP-1 with hexagon rings, zigzag edges, and long alkyl side chains provides a large number of free radicals during pyrolysis, promoting the parallel arrangement of aromatic molecules. Special addition patterns (linear and nonlinear simultaneous) of aromatic molecular in CTP-3 generate a large number of edge carbons and surface defects in the carbonized products. The high viscosity and arm-chair edge reduce the reactivity of CTP-4 molecules, and the presence of loops and oxygenated aromatics in CTP-4 also reduces the orientation of carbon stacks and the flatness of the microstructure. The electrochemical performance of the final products shows a significant difference. Among them, CTP-1-M-1400 with a specific capacity of 349 mAh g−1 at 0.1 A g−1 displays an excellent cycling performance. Large amounts of Li-ions (about 39.2 %) are stored at the edge and surface of CTP-3-M-1400. While large number of Li-ions (about 23.5 %) are stored in the microspaces of CTP-4-M-1400. In addition, excessive structure defects and oxygen-containing groups in CTP-4-M-1400 lead to decreased capacity retention.

Determination of Binding Constants and Gas Phase Stabilities of Artificial Carbohydrate Receptor Complexes Using Electrospray Mass Spectrometry.

In recent years, binding studies to determine complex stabilities and selectivities of artificial carbohydrate receptors with glycosides have been mainly performed using 1H NMR, isothermal titration calorimetry (ITC), and other spectroscopic titration techniques. Native electrospray ionization (ESI) mass spectrometry is used only to verify the complex stoichiometries, although determination of dissociation constants is also possible. Herein, the binding of a 1,3,5-substituted 2,4,6-triethylbenzene-based receptor (CHR) to four alkyl-β-d-glucosides with varying alkyl side chain lengths (methyl (MGP), hexyl (HGP), octyl (OGP), and dodecyl (DGP)-β-d-glucosides), which was analyzed by ESI Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) under optimized spray conditions in both ion modes, is reported. The complexes of the receptor with different sugars could be detected in 1:1 and 2:1 stoichiometries. Dissociation constants calculated for the 1:1 complexes showed a stability trend depending on the length of the alkyl side chain of the sugar: CHR:DGP > CHR:OGP > CHR:HGP > CHR:MGP. Gas phase stabilities determined by CID-MS confirm this relative trend in binding affinities. These findings substantiate the validity and applicability of ESI-MS as a method for investigating noncovalent complex stabilities and thus support research in the field of molecular recognition of carbohydrates by artificial receptors.

Effect of Hydrophobic Acrylic Monomers with Different Alkyl Side Chain Lengths on Reducing the Glistening of Hydrophobic Acrylic Intraocular Lens Materials

AbstractGlistening is the condensation of water that forms within the intraocular lens (IOL) materials. In this study, a new approach was attempted to reduce the glistening of IOL materials by introducing hydrophobic acrylic monomers with different alkyl side chain lengths into the IOL materials. Various hydrophobic acrylic monomers such as butyl acrylate (BA), 2‐ethylhexyl acrylate (EHA), and dodecyl acrylate (DA) were copolymerized with a hydrophobic acrylic monomer, 2‐phenoxyethyl acrylate, respectively. In this process, we investigated the effect of the alkyl side chain lengths of hydrophobic acrylic monomers on the glistening of hydrophobic acrylic IOL materials. As the content of hydrophobic acrylic monomers (BA, EHA, and DA) increased, the glistening of IOL materials decreased significantly for all hydrophobic acrylic monomers. At the same content of hydrophobic acrylic monomers, the IOL material showed the least content of glistening when copolymerized with DA. However, the IOL material obtained using BA exhibited the largest content of glistening, indicating that the glistening reduction effect was large in the order of DA>EHA>BA. These findings show that the glistening of IOL materials decreases with increasing alkyl side chain lengths of hydrophobic acrylic monomers.

Halogen‐free solvent processed organic solar sub‐modules (≈55 cm2) with 14.70% efficiency by controlling the morphology of alkyl chain engineered polymer donor

AbstractGoals of high efficiency, morphological analysis, and the ability to produce organic solar cell (OSC) sub‐modules using halogen‐free solvents are demanding. In this study, a robust conjugated polymer with thienothiophene π‐spacer with pendant alkyl side chain (NapBDT‐C12) was synthesized and used to fabricate sub‐modules. Excellent efficiencies were demonstrated by a NapBDT‐C12 integrated ternary blend, which was used to produce stable small‐area‐to‐sub‐module devices using O‐xylene. The efficiency of the NapBDT‐C12 added small‐area ternary devices (PM6:NapBDT‐C12:L8‐BO) was 18.71%. Owing to the controlled homogeneity of the blend with favorable nanoscale film morphology, enhanced carrier mobilities, and exciton dissociation/splitting properties, contributed to the efficiencies of small‐area‐to‐sub‐module OSCs. Moreover, a 55 cm2 sub‐module with an efficiency of 14.69% was accomplished by bar coating using O‐xylene under ambient conditions. This study displays the potential of a ternary blend based OSC device to produce high efficiency scalable sub‐modules at ambient conditions.image

Uncovering Backbone Conformation for Rigid DPP-Based Donor-Acceptor Conjugated Polymer Using Deuterium Labeling and Neutron Scattering.

The conjugated polymer's backbone conformation dictates the delocalization of electrons, ultimately affecting its optoelectronic properties. Most conjugated polymers can be viewed as semirigid rods with their backbone embedded among long alkyl side chains. Thus, it is challenging to experimentally quantify the conformation of a conjugated backbone. Here, we performed contrast variation neutron scattering on rigid conjugated donor-acceptor (D-A) diketopyrrolopyrrole (DPP) polymers with selectively deuterated side chains to measure the conjugated backbone conformation. We first synthesized DPP-based polymers with deuterated side chains, confirmed by NMR and FTIR. Using contrast variation neutron scattering, we found that the DPP-based conjugated polymers are much more rigid than poly(3-alkylthiophenes), with persistence length (L p) at 16-18 nm versus 2-3 nm. More importantly, in contrast to the relatively flexible poly(3-alkylthiophenes) whose backbone is more flexible than the whole polymer, we found that the backbone of DPP-based polymers has the same L p value compared to the whole polymer chain. This indicates that side chain interference on backbone conformation is not present for the semirigid polymer, which is further confirmed by coarse-grained molecular dynamics (CG-MD) simulations. Our work provides a novel protocol to probe polymer's backbone conformation and paradigm-shifting understanding of the backbone conformation of semirigid conjugated polymers.

Effects of Alkyl Side Chain Length on the Structural Organization and Proton Conductivity of Sulfonated Polyimide Thin Films

Effects of Alkyl Side Chain Length on the Structural Organization and Proton Conductivity of Sulfonated Polyimide Thin Films

Intrinsic role of alkyl side chains in disorder, aggregates, and carrier mobility of nonfullerene acceptors for organic solar cells: A multiscale theoretical study

Intrinsic role of alkyl side chains in disorder, aggregates, and carrier mobility of nonfullerene acceptors for organic solar cells: A multiscale theoretical study

Molecular Ordering Manipulation in Fused Oligomeric Mixed Conductors for High-Performance n-Type Organic Electrochemical Transistors.

Advanced n-type organic electrochemical transistors (OECTs) play an important part in bioelectronics, facilitating the booming of complementary circuits-based biosensors. This necessitates the utilization of both n-type and p-type organic mixed ionic-electronic conductors (OMIECs) exhibiting a balanced performance. However, the observed subpar electron charge transport ability in most n-type OMIECs presents a significant challenge to the overall functionality of the circuits. In response to this issue, we achieve high-performance OMIECs by leveraging a series of fused electron-deficient monodisperse oligomers with mixed alkyl and glycol chains. Through molecular ordering manipulation by optimizing of their alkyl side chains, we attained a record-breaking OECT electron mobility of 0.62 cm2/(V s) and μC* of 63.2 F/(cm V s) for bgTNR-3DT with symmetrical alkyl chains. Notably, the bgTNR-3DT film also exhibits the highest structural ordering, smallest energetic disorder, and the lowest trap density among the series, potentially explaining its ideal charge transport property. Additionally, we demonstrate an organic inverter incorporating bgTNR-3DT OECTs with a gain above 30, showcasing the material's potential for constructing organic circuits. Our findings underscore the indispensable role of alkyl chain optimization in the evolution of prospective high performance OMIECs for constructing advanced organic complementary circuits.

Hydrophobic assembly of molecular catalysts at the gas-liquid-solid interface drives highly selective CO2 electromethanation.

Molecular catalysts offer tunable active and peripheral sites, rendering them ideal model systems to explore fundamental concepts in catalysis. However, hydrophobic designs are often regarded as detrimental for dissolution in aqueous electrolytes. Here we show that established cobalt terpyridine catalysts modified with hydrophobic perfluorinated alkyl side chains can assemble at the gas-liquid-solid interfaces on a gas diffusion electrode. We find that the self-assembly of these perfluorinated units on the electrode surface results in a catalytic system selective for electrochemical CO2 reduction to CH4, whereas every other cobalt terpyridine catalyst reported previously was only selective for CO or formate. Mechanistic investigations suggest that the pyridine units function as proton shuttles that deliver protons to the dynamic hydrophobic pocket in which CO2 reduction takes place. Finally, integration with fluorinated carbon nanotubes as a hydrophobic conductive scaffold leads to a Faradaic efficiency for CH4 production above 80% at rates above 10 mA cm-2-impressive activities for a molecular electrocatalytic system.

Ni-catalysed remote C(sp3)-H functionalization using chain-walking strategies.

The dynamic translocation of a metal catalyst along an alkyl side chain - often coined as 'chain-walking' - has opened new retrosynthetic possibilities that enable functionalization at unactivated C(sp3)-H sites. The use of nickel complexes in chain-walking strategies has recently gained considerable momentum owing to their versatility for forging sp3 architectures and their redox promiscuity that facilitates both one-electron or two-electron reaction manifolds. This Review discusses the relevance and impact that these processes might have in synthetic endeavours, including mechanistic considerations when appropriate. Particular emphasis is given to the latest discoveries that leverage the potential of Ni-catalysed chain-walking scenarios for tackling transformations that would otherwise be difficult to accomplish, including the merger of chain-walking with other new approaches such asphotoredox catalysis or electrochemical activation.

Impact of side chain length on the properties and alkaline fuel cell performance of OEG-grafted poly(terphenyl piperidinium) anion exchange membranes

In designing comb-shaped anion exchange membranes (AEMs), replacing alkyl side chains with ethylene glycol (EG)-based ones significantly enhances membrane properties and boosts AEM fuel cell performance. Although much research has focused on optimizing the placement of EG segments within the polymer matrix, the effect of EG chain length remains less explored. In this work, a series of poly(terphenyl piperidinium) AEMs with N-oligo(ethylene glycol) (OEG) terminal pendants having two to five EG repeating units were prepared by simple post-polymerization quaternization. The membrane properties showed a strong correlation with the length of the OEG side chains, influenced by both chemical composition and phase behavior. Among the OEG-grafted AEMs, PTP-OEG3 with moderate three EG repeating units, exhibited the best properties due to a careful balance between EG and cationic groups, leading to a favorable microphased separation. It achieved high hydroxide conductivity (114 mS cm−1 at 80 °C in water), robust mechanical strength (tensile strength >52 MPa), and good ex situ alkaline stability. As a result, the AEM fuel cells with the property-balanced PTP-OEG3 membrane achieved the highest peak power density of 976 mW cm−2. The in situ stability of these AEMs was also investigated. Evidently, understanding the optimal EG side chain length is an important criterion for designing AEM materials for alkaline fuel cells.

Mechanism study on rheological response of thermally pretreated waxy crude oil

Pre-heating treatment significantly influences the low-temperature flow characteristics of waxy crude oil, yet its underlying mechanism warrants further investigation. This study explores the effects of pre-heating temperatures (60–110 °C) on the rheological characteristics of waxy crude oil from Nanyang using 1H NMR, DSC, Microscopic Observation, and Rheological Property Test. Findings reveal that asphaltenes increasingly dissolve at the pre-heating temperature of 70 °C, improving their capacity to act as nucleation sites for wax crystals. Consequently, the wax appearance temperature (WAT) increases. Meanwhile, the rheological parameters of the crude oil decrease and wax crystals exhibit smaller and tighter rod-like structures. Further growing the pre-heating temperature to 80 °C induces a comprehensive effect: alterations in asphaltene polarity, hindrance of asphaltene aggregation by alkyl side chains, and self-aggregation of alkyl side chains. This results in decreased WAT, along with the lowest rheological parameter values, with wax crystals appearing as the smallest and tightest dot-like shapes. At 80 °C, the optimal ratio between asphaltene polarity and alkyl side chain characteristics promotes strong nucleation and co-crystallization between asphaltene and wax crystals, maximizing asphaltene's ability to enhance the crude oil's low-temperature flowability. However, as the pre-heating temperature continues to rise, WAT decreases slightly and the rheological response starts to deteriorate.

Surfactant-Free Preparation of Conjugated Polymer Nanoparticles in Aqueous Dispersions Using Sulfate Functionalized Fluorene Monomers.

Conjugated polymer nanoparticles (CPNs) can be synthesized by a Suzuki-Miyaura cross-coupling miniemulsion polymerization to give stable dispersions with a high concentration of uniform nanoparticles. However, large amounts of added surfactants are required to stabilize the miniemulsion and prevent the aggregation of the nanoparticles. Removal of the excess surfactant is challenging, and residual surfactant in thin films deposited from these dispersions can reduce the performance of optoelectronic devices. We report a novel approach to prepare stable dispersions with no added surfactant using a fluorene monomer, 2,7-dibromo-9,9-bis(undecanesulfate)-9H-fluorene, with alkyl side chains terminated by negatively charged sulfate groups. This functionality mimics the structure of one of the most commonly used surfactants, sodium dodecyl sulfate (SDS). This charged monomer effectively stabilizes the miniemulsion through electrostatic repulsion without the use of any additional surfactant in molar ratios ranging from 2.0 to 20.0 mol % of total monomer content for the preparation of poly(9,9-dioctylfluorene) (PFO) and poly(9,9-dioctylfluorene-alt-bithiophene) (PF8T2). Incorporation of 5.0 mol % of the amphiphilic monomer gave stable dispersions with a surface potential below -40 mV and, and polymers with molar mass (Mn) above 10 kg mol-1. This method should be generally applicable to the preparation of dispersions of polyfluorenes for application in organic electronic and optoelectronic devices without the requirement for time-consuming processes to remove residual surfactant.