Alkyl Chain Length Research Articles

Thermal Conductivity in Side-Chain Liquid-Crystal Epoxy Polymers: Influence of Mesogen Structure.

Side-chain liquid-crystal epoxy polymers (SCLCEPs) are valued for their unique properties, which combine LC side chains with epoxide-based polyether main chains for ordered molecular arrangements. They have high thermal conductivity and optical properties due to their low polydispersity and high crystallinity. Achieving optimal thermal conductivity in SCLCEPs involves addressing factors such as mesogen nature, polymer design, and alignment within the polymer structure. Balancing these factors enhances their suitability for heat dissipation in advanced materials. In this study, SCLCEPs with a polyethylene glycol backbone and laterally arranged mesogens are synthesized via anionic ring opening of mesogenic epoxides with unique LC phases. These monomers, which feature biphenyl mesogens attached to glycidyloxy ether and different alkyl chain lengths on the other side, is designed to facilitate mesogen self-assembly and interaction. The resulting polymers exhibited higher crystallinity and LC phases than the monomers. Notably, because of their LC nature, their thermal conductivity exceeds 0.48 W·m-1 K-1 and increases with shortened alkyl chain lengths, reaching 0.57 W·m-1 K-1. This research expands the applications of SCLCEPs in advanced fields requiring enhanced thermal properties.

Effect of Alkyl Chain Length on the Magnitude of Dynamically Correlated Molecules and Dynamical Crossover in Alkyltriethylammonium-Based Ionic Liquids.

This study explores the impact of alkyl chain length on dynamic heterogeneity and dynamic crossover in alkyltriethylammonium-based ionic liquids ([TEA-R][TFSI]) with varying alkyl chain lengths (R = C6, C8, and C10). Using differential scanning calorimetry and broadband dielectric spectroscopy, we observed that these ionic liquids are excellent glassformers with notable ionic conductivity at room temperature. Furthermore, the number of dynamically correlated molecules at the glass transition temperature, reflecting the dynamic heterogeneity, is exceptionally small for TEA-R ILs and becomes more reduced with longer alkyl chains. Moreover, the temperature dependence of conductivity requires two Vogel-Fulcher-Tammann equations with distinct sets of fitting parameters for an accurate description. The crossover temperature Tb, indicating the transition to complex dynamics, increases with the alkyl chain length.

Stability and Fibrillation of Lysozyme in the Mixtures of Ionic Liquids with Varying Hydrophobicity.

Combinatorial effects of small molecules provide newer avenues to improve protein stability. The combined effect of two different classes of ILs on the stability and fibrillation of lysozyme was investigated. Imidazolium-ILs (aromatic-moiety) with varying alkyl chains, methyl (MIC), butyl (BMIC) and hexyl (HMIC), and pyrrolidinium-IL (alicylic-moiety) with butyl substitution (BPyroBr) were chosen. The fibrillation was delayed by all the ILs. In mixtures, the presence of HMIC with MIC or BMIC at 2:1 ratio delayed the fibrillation synergistically by increasing lag-time and reducing elongation rate. Lysozymes's stability was reduced at these conditions compared to lower molar ratios of HMIC with MIC or BMIC. Computational studies indicated that water molecules were reduced around lysozyme upon adding Im-ILs, whereas BPyroBr slightly increased water. Preferential interaction studies suggest that the binding of HMIC with the protein was the most favored and it synergistically facilitated the binding of MIC. BMIC was preferentially binding to lysozyme but disfavoured the interaction of MIC whereas BMIC and BPyroBr had a competitive binding. The mixture of ILs containing the longer alkyl chain destabilizes the protein more, but delays the fibrillation. Further, the effect of aromatic ILs could be greater than alicyclic ILs having the same alkyl chain length.

Developmental Toxicity of Alkylated PAHs and Substituted Phenanthrenes: Structural Nuances Drive Diverse Toxicity and AHR activation

Polycyclic aromatic hydrocarbons (PAHs) are a diverse class of chemicals that occur in complex mixtures including parent and substituted PAHs. To understand the hazard posed by complex environmental PAH mixtures, we must first understand the structural drivers of activity and mode of action of individual PAHs. Understanding the toxicity of alkylated PAHs is important as they often occur in higher abundance in environmental matrices and can be more biologically active than their parent compounds. 104 alkylated PAHs were screened from 11 different parent compounds with emphasis on substituted phenanthrenes and their structurally dependent toxicity differences. Using a high-throughput early life stage zebrafish assay, embryos were exposed to concentrations between 0.1 to 100 μM and assessed for morphological and behavioral outcomes. The aryl hydrocarbon receptor (AHR) is often implicated in the toxicity of PAHs and the induction of cytochrome P4501A (cyp1a) is an excellent biomarker of Ahr activation. Embryos were evaluated for cyp1a induction using a fluorescence reporter line. Alkyl and polar phenanthrene derivatives were further assessed for spatial cyp1a expression and Ahr dependence of morphological effects. In the alkyl PAH screen 35 (33.7%) elicited a morphological or behavioral response and of those 23 (65%) also induced cyp1a. 31 (29.8%) of the chemicals only induced cyp1a. Toxicity varied substantially in response to substitution location, the amount of ring substitutions and alkyl chain length. Cyp1a induction varied by parent compound group and was a poor indicator of morphological or behavioral outcomes. Polar phenanthrenes were more biologically active than alkylated phenanthrene derivatives and their toxicity was not dependent upon the Ahr2, Ahr1a or Ahr1b when tested individually, despite cyp1a induction by 50% of polar phenanthrenes. Our results demonstrated that induction of cyp1a did not always correlate with PAH toxicity or Ahr dependence and that the type and location of phenanthrene substitution determined potency.

Bench to Any Side—The Pharmacology and Applications of Natural and Synthetic Alkylated Hydroxy Cinnamates and Cinnamides

Natural alkylated hydroxy cinnamates (AHCs) isolated from medicinal plants and the thereby designed and synthesized cinnamides are derivatives of hydroxy cinnamic acids such as p-coumaric, sinapic, ferulic, and caffeic acids, which are naturally derived from human dietary sources. The pharmacological properties displayed by AHCs based on their inherent structure range include antioxidant, antimicrobial, antiplasmodial, anti-tyrosinase, Alzheimer’s and Parkinson’s disease therapy, anticancer therapy, metabolic disease therapy, and biopesticides, which have not been reviewed together. Based on their inherent antioxidant, antimicrobial, and UV absorption and their structure–activity relationships, these cinnamyl esters and amides can be used for food preservation in emulsions and oils, as sun-protective components of skin care formulations, and in many other multifunctional applications. In conclusion, the fine-tuning of the structural features such as the type of hydroxy cinnamic acid used, the length of alkyl chains for variable lipophilicity, conversion from cinnamic to propanoic for antioxidants, the increase in methoxy or the change to amino groups to increase the molar absorption coefficient and loss of absorption values, the substitution by halides or amino groups for potent biopesticides, and conversion from esters to amide bonds leads to different AHCs for biomedical, cosmetic, and agriculture applications as an emerging field of investigation that can overall provide natural, safe, biodegradable, and sustainable molecules.

Influence of Alkyl Chain Length and Bromine Substitution on Thermal, Photophysical, and Optical Properties of Biphenyl Luminescent Molecules

This study investigates a series of bromine-substituted alkoxy biphenyl derivatives to explore their potential as luminescent and optical materials for applications in display technologies, sensors, and photonic devices. Four compounds were synthesized, including 5-Br, 6-Br, 7-Br, and a comparative non-halogenated molecule 6-H. The findings reveal that the bromine-substituted derivatives exhibit enhanced thermal stability as the alkoxy chain length increases, though none of the compounds displayed liquid crystalline phases, likely due to molecular flexibility and steric hindrance from the bromine atoms. Photophysical studies showed that the compounds exhibit tunable emission colors ranging from green to blue, depending on the side chain length and the presence or absence of bromine. Importantly, the introduction of bromine was found to enhance the photophysical properties, including increased quantum yields and longer emission lifetimes, compared to the non-halogenated analog. Moreover, these luminescent molecules can maintain strong fluorescence both in solution and when forming aggregates. Furthermore, the optical properties, such as dielectric constant, extinction coefficient, refractive index, and optical conductivity, were thoroughly examined. The results indicate that structural variations, including alkyl chain length and bromine substitution, significantly influence the capability of these materials to store and dissipate electrical energy. Their strong optical responses, high energy storage capabilities, and sensitivity to structural modifications suggest that the studied materials have substantial potential for applications in energy storage, sensing, optoelectronics, and non-linear optics. These findings offer important guidelines for the rational design of multifunctional luminescent and optical materials, representing a significant step forward in the development of practical applications of smart materials and advanced photonic devices.

Highly selective separation of 99TcO4−/ReO4− with rapid liquid-liquid two-phase disengagement by amine-diamide ligands

Efficient and selective extraction of pertechnetate (TcO4−) from nitric acid medium has become a significant challenge, especially in the presence of a large excess of interfering anions. By employing a combined strategy involving H-bonding and electrostatic interaction, a highly selective extraction of TcO4− can be achieved. The present work reports three homologous amine-diamide ligands with different alkyl chain lengths on the amine N atom of 2,2′‐(metylimino)bis(N,N‐dioctylacetamide) (MIDOA), 2,2′‐(butylimino)bis(N,N‐dioctylacetamide) (BIDOA) and 2,2′‐(octylimino)bis(N,N‐dioctylacetamide) (OIDOA), and their extraction behaviors for TcO4−/ReO4− in HNO3 solution are also investigated by using n-dodecane as a diluent. It has been shown that all of them exhibit excellent extractability and high selectivity to TcO4−/ReO4−. Their extractability and phase disengagement follow the order of OIDOA > BIDOA > MIDOA, revealing a greater extractability and rapider phase disengagement for the amine-diamide ligand with longer chain substituents on the amine N atom. Both slope analysis and loading capacity test indicate the formation of 1:1 metal/ligand extracted complex, which is also confirmed by the analyses of single-crystal X-ray diffraction (SC-XRD), electrospray ionization mass (ESI-MS), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). The extraction of TcO4−/ReO4− by the amine-diamide ligand follows the anion exchange extraction model and is a spontaneous and endothermic process. Furthermore, a competing extraction test was also conducted and demonstrates excellent extractability and high selectivity to TcO4−/ReO4−.

DFT study of the effect of substitution and of the alkyl chain length on optical properties and polarizabilities of CnF2(COX) (X = O, S, Se)

DFT study of the effect of substitution and of the alkyl chain length on optical properties and polarizabilities of CnF2(COX) (X = O, S, Se)

Influence of alkyl chain lengths and positions on visible-light absorbing triphenylamine oxime esters for free radical photopolymerization

Influence of alkyl chain lengths and positions on visible-light absorbing triphenylamine oxime esters for free radical photopolymerization

Enhancing Hole Transport and Autonomous Healing Properties of Supramolecular Columns in Unsymmetrical Discotics.

Designing smart autonomous healing soft materials is crucial to attaining cost-efficiency and optimal performance in organic semiconductors. In this context, we design an unsymmetrical thiophene-fused phenazine (TFP)-based discotic liquid crystal (DLC) with the goal of creating an active organic semiconductor that encompasses favorable attributes, such as polarizability, mobility, and processability. Aligned with our objective, we successfully synthesized two unsymmetrical TFP core-based DLCs by linking alkyl chains of variable lengths at the periphery through a coupling reaction. These DLCs show room temperature columnar oblique (Colob) mesophase as evident from temperature-dependent studies employing polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS). We performed space charge-limited current (SCLC) techniques to evaluate the hole mobility of TFP-based DLCs and found that they have high hole mobility (∼10-3 cm2/V s). Additionally, the film morphology and its self-healing nature have been examined using atomic force microscopy (AFM) and stress relaxation test. One of the unsymmetrical DLCs exhibited an ability to relax stress over time while maintaining a constant strain (up to 1-3%). The rational design of these unsymmetrical discotics, exhibiting reduced threshold voltage (as confirmed by conductivity studies) highlights their possible potential in various organic semiconductor devices.

Ionic Character and Alkyl Chain Length of Surfactants Affect Titanium Dioxide Dispersion and Its UV-Blocking Efficacy

The dispersion of titanium dioxide (TiO2) determines the performance of TiO2-based formulations in cosmetic and coating applications. In particular, the chemical and structural characteristics of the surfactants used to prepare TiO2 dispersions are significant. However, the influence of surfactants on TiO2 dispersion quality has not been systematically investigated. In this study, we observed the effects of the ionic character of commercial surfactants on the dispersion stability and UV-blocking efficacy of TiO2. Among the experimental surfactant groups, anionic sodium dodecyl sulfate was efficient in stabilizing TiO2 as a water-in-oil formulation and enhancing its UV-blocking efficacy. Furthermore, an anionic fatty acid as a surfactant with a longer alkyl chain length was sufficient to stabilize the TiO2 formulation, which also displayed the highest UV-blocking efficacy, comparable to the values of commercial TiO2-based cosmetic products.

Effect of Surface Functionalization of Si3N4 Fillers on Thermal and Mechanical Properties of TIMs

AbstractThermal interface materials (TIMs), which consist of polymers and thermally conductive fillers, are crucial for improving heat dissipation. This study examines the impact of surface functionalization of Si₃N₄ thermal conductive fillers on the performance of TIMs. Si₃N₄ fillers are modified with silane coupling agents of varying alkyl chain lengths, producing fillers with contact angles ranging from 25° to 151.2°, thereby ensuring enhanced interfacial compatibility with various polymers. The modified fillers are incorporated into three common polymers—silica gel (SG), epoxy resin (EP), and polyurethane (PU)—to fabricate TIMs. When the contact angle of Si₃N₄ fillers is 73.3°, they demonstrate excellent interfacial compatibility with EP, leading to a 54.37% increase in thermal conductivity and a 162.75% enhancement in elongation at break for the TIM. At a contact angle of 132.7°, the TIMs prepared with SG exhibit an 86.36% increase in thermal conductivity and a 23.88% increase in elongation at break. Given that the original Si₃N₄ already possesses adequate interfacial compatibility with PU, no further modification is required. These findings offer valuable insights for future research aimed at optimizing Si₃N₄ fillers and TIMs to achieve enhanced thermal and mechanical properties.

Self‐Assembled Bent Perylenediimides

The properties of π‐functional materials are predominantly influenced by both their molecular structures and interactions between π‐systems. Recent advancements have focused on modifying the geometry or topology of π‐molecules from planar to nonplanar conformations to tailor molecular properties. However, the interactions among nonplanar π‐molecules remain largely unexplored, likely due to the significant reduction in contact surfaces arising from their curved structures. Herein, we investigated the electro‐optical properties and π‐stacking behaviors of a series of bent perylenediimides (B‐PDIs) with gradual changes in bending angles, achieved by altering the lengths of linear alkyl chains connecting the two nitrogen positions of each PDI. Curvature‐dependent self‐assembly of these bent PDIs is observed, which is primarily driven by dipole‐dipole interactions rather than dispersion forces. More importantly, fine‐tuning intermolecular coupling through bending enables excited‐state symmetry‐breaking charge separation in [n]B‐PDIs (n = 16, 12) in the crystalline solid state.

Self-Assembled Bent Perylenediimides.

The properties of π-functional materials are predominantly influenced by both their molecular structures and interactions between π-systems. Recent advancements have focused on modifying the geometry or topology of π-molecules from planar to nonplanar conformations to tailor molecular properties. However, the interactions among nonplanar π-molecules remain largely unexplored, likely due to the significant reduction in contact surfaces arising from their curved structures. Herein, we investigated the electro-optical properties and π-stacking behaviors of a series of bent perylenediimides (B-PDIs) with gradual changes in bending angles, achieved by altering the lengths of linear alkyl chains connecting the two nitrogen positions of each PDI. Curvature-dependent self-assembly of these bent PDIs is observed, which is primarily driven by dipole-dipole interactions rather than dispersion forces. More importantly, fine-tuning intermolecular coupling through bending enables excited-state symmetry-breaking charge separation in [n]B-PDIs (n = 16, 12) in the crystalline solid state.

Enhancing the Pressure-Sensitive Electrical Conductance of Self-Assembled Monolayers.

The inherent large HOMO-LUMO gap of alkyl thiol (CnS) self-assembled monolayers (SAMs) has limited their application in molecular electronics. This work demonstrates significant enhancement of mechano-electrical sensitivity in CnS SAMs by external compression, achieving a gauge factor (GF) of approximately 10 for C10S SAMs. This GF surpasses values reported for conjugated wires and DNA strands, highlighting the potential of CnS SAMs in mechanosensitive devices. Conductive atomic force microscopy (cAFM) investigations reveal a strong dependence of GF on the alkyl chain length in probe/CnS/Au junctions. This dependence arises from the combined influence of molecular tilting and probe penetration, facilitated by the low Young's modulus of alkyl chains. Theoretical simulations corroborate these findings, demonstrating a shift in the electrode Fermi level toward the molecular resonance region with increasing chain length and compression. Introducing a rigid graphene interlayer prevents probe penetration, resulting in a GF that is largely independent of the alkyl chain length. This highlights the critical role of probe penetration in maximizing mechano-electrical sensitivity. These findings pave the way for incorporating CnS SAMs into mechanosensitive and mechanocontrollable molecular electronic devices, including touch-sensitive electronic skin and advanced sensor technologies. This work demonstrates the potential of tailoring mechanical and electrical properties of SAMs through molecular engineering and interface modifications for optimized performance in specific applications.

Direct Covalent Functionalization of H-Terminated 2D Germanane with Thiolated Molecules: Passivation and Tuning of Optoelectronic Properties.

Covalent molecular functionalization allows the physicochemical properties of 2D materials to be precisely tuned and modulated on-demand. Nonetheless, research on the molecular functionalization of 2D monoelemental graphene-like materials─known as Xenes─remains scarce, being mainly restricted to a specific type of solid-state chemical reaction based on the topotactic transformation of bulkier Zintl phases. Herein, a robust and general chemical approach is reported for the direct functionalization of commercially available H-terminated 2D germanene (2D-GeH) with thiolated molecules (R-SH) via Ge-S bond formation. While the material characterization data provide direct experimental evidence of the Ge-S chemical bonding, density functional theory (DFT) calculations also predict its existence. Remarkably, the anchored thiolated molecules also favor the passivation of the 2D Xene against air oxidation, enlarging its benefits for real implementation. As a proof-of-principle, a redox-responsive molecular moiety such as 6-(ferrocenyl)hexanethiol (Fc6-SH) has been exploited to induce changes in the optoelectronic properties of the resulting 2D-GeFc6 heterostructure by simply modulating the external bias potential, making it possible to optically and electrically read out a molecular switch on 2D Xene via implanting molecular responsiveness. Remarkably, the ON/OFF ratio has been shown to be dependent on the distance between the redox-responsive Fc moiety and the 2D Xene surface through the alkyl chain length. Overall, the reported a-la-carte molecular engineering approach provides the basis toward the rapid development of stable 2D-GeR derivatives exhibiting molecule-programmable properties.

Synergistic Modulation of Orientation and Steric Hindrance Induced by Alkyl Chain Length in Ammonium Salt Passivator Toward High‐performance Inverted Perovskite Solar Cells and Modules

AbstractOrganic ammonium salts are extensively utilized for passivating surface defects in perovskite films to mitigate trap‐assisted nonradiative recombination. However, the influence of alkyl chain length on the molecular orientation and spatial steric hindrance of ammonium salt remains underexplored, hindering advancements in more effective passivators. Here, a series of organic ammonium salts is reported with varying alkyl chain lengths to passivate surface defects and optimize band alignment. It is revealed that long alkyl chains promote parallel molecular orientation on the perovskite surface, thereby reinforcing interaction with surface defects, whereas excessive chain length introduces steric hindrance, weakening anion‐perovskite interactions. Nonylammonium acetate (NAAc) with optimal chain length achieves the ideal balance between chemical interactions, resulting in superior passivation. Through NAAc passivation, high‐performance inverted perovskite solar cells (PSCs) and modules are achieved, with power conversion efficiencies (PCE) of 25.79% (certified 25.12%) and 19.62%, respectively. This marks a record PCE for inverted PSCs utilizing vacuum flash technology in ambient conditions. Additionally, the NAAc‐passivated devices retain 91% of their initial PCE after 1200 h of continuous maximum power point operation. This work offers new insights into the interplay between molecular orientation and steric hindrance, advancing the design of high‐performance PSCs.

Revealing the antioxidant properties of alkyl gallates: a novel approach through quantum chemical calculations and molecular docking.

This study investigates the antioxidant potential of alkyl gallates (C1-C10), focusing on the impact of alkyl chain length and solvent polarity on their antioxidant properties. Known for their biomedical relevance in mitigating oxidative stress, alkyl gallates' structure-activity relationships, particularly regarding chain length and environmental factors, still need to be explored. Key thermochemical parameters, including bond dissociation enthalpy (BDE), ionization potential (IP), proton affinity (PA), and electron transfer enthalpy (ETE), reveal that shorter alkyl chains (C1-C4) exhibit superior antioxidant activity. In contrast, longer chains (C5-C10) show reduced effectiveness due to steric hindrance and lower solubility in polar solvents. Molecular docking studies also demonstrated favorable binding interactions with vital biological targets, further reinforcing their antioxidant potential. Quantum chemical calculations were performed using Gaussian 16 with the B3LYP/6-311G(dp) basis set for geometry optimizations. Solvent effects were modeled using the integral equation formalism-polarized continuum model (IEF-PCM). Molecular docking studies were conducted using AutoDockTools 4.2, targeting Tyrosine Kinase Hck, Heme Oxygenase, and Human Serum Albumin to evaluate fundamental binding interactions. These computational methods provided insights into alkyl gallates' chemical reactivity and antioxidant efficiency, allowing for the rational design of more potent antioxidant compounds.

Colorimetric sensors of ultraviolet-C light using diacetylene-zinc(II)-zinc oxide nanocomposites with tunable sensitivity

Polydiacetylene (PDA) material-based colorimetric sensors have been devised for monitoring ultraviolet-C (UVC) light. However, it is rather difficult to systematically control their sensitivity. This work introduces an easy and inexpensive approach for developing diacetylene/zinc(II)/zinc oxide (DA/Zn2+/ZnO) nanocomposites as colorimetric sensors of UVC light. Here, we demonstrate the ability to tune the sensitivity of the nanocomposites to UVC light by varying different parameters including ZnO ratio, ZnO size, and alkyl chain length of DA monomers. We have found that the increase of ZnO ratio significantly enhances the UVC sensitivity. Furthermore, the color transition from blue to purple upon prolonged exposure to UVC light can be controlled by adjusting the ZnO ratio. Interestingly, the use of ZnO quantum dots with a diameter of 3.8 nm drastically increases the sensitivity to UVC light. The adjustment in DA alkyl chain length also enables fine-tuning of sensitivity. The shortening of the alkyl chain length at the tail and headgroup position strongly influences the color-transition behaviors of the nanocomposites upon increasing the UVC irradiation time. Two different types of UVC sensors can be fabricated including flexible film and hydrogel bead sensors. These sensors exhibit a color transition from yellow to green to red as UVC exposure increases from 0 to 16.4 J/cm2.

Alkyl sucrose esters vs. Brijs: How chain length and temperature impact surface and foam properties

The primary objective of this study is to determine the similarities and differences in the surface, film, and foam properties of alkyl sucrose esters (SEs) with high monoester content (≥70 %) and polyoxyethylene alkyl ethers (Brijs) with a high number of ethoxy groups (≥20) in their head group. Experiments were conducted using surfactant molecules with alkyl chain lengths of 12, 16, and 18 carbon atoms at concentrations between 0.01 and 1 wt%, within a temperature range of 25 °C to 60 °C.The lag time for surfactant adsorption increased with surfactant chain length, decreased with temperature, and significantly decreased with surfactant concentration for both types of studied surfactants. However, increasing the chain length from 12 to 18 carbon atoms led to a 10-fold increase in lag time for Brijs and more than a 600-fold increase for SEs. This effect rendered longer-chain SEs incapable of forming voluminous foam in Bartsch test and led to pronounced coalescence between the bubbles after their separation from the sparger in the foam rise method, resulting in foams with very large bubbles, which exhibited lower stability. The utilization of a Kenwood mixer for foam generation provided sufficient time for longer-chain SE molecules to adsorb on the bubble surfaces and to produce voluminous foams with small bubbles, which remained stable even at 60 °C. In contrast, foams generated from Brijs solutions are very unstable at 60 °C. The long-standing stability of SEs foam was attributed to the formation of mixed mono- and diesters adsorption layers on the bubble surfaces.