Multiple Alkyl Chains Research Articles

Near-Infrared II Agent with Excellent Overall Performance for Imaging-Guided Photothermal Thrombolysis.

Near-infrared II (NIR-II) imaging and photothermal therapy hold tremendous potential in precision diagnosis and treatment within biological organisms. However, a significant challenge is the shortage of NIR-II fluorescent probes with both high photothermal conversion coefficient (PCE) and fluorescence quantum yield (ΦF). Herein, we address this issue by integrating a large conjugated electron-withdrawing core, multiple rotors, and multiple alkyl chains into a molecule to successfully generate a NIR-II agent 4THTPB with excellent PCE (87.6%) and high ΦF (3.2%). 4THTPB shows a maximum emission peak at 1058 nm, and the emission tail could extend to as long as 1700 nm. These characteristics make its nanoparticles (NPs) perform well in NIR-II high-resolution angiography, thereby allowing for precise diagnosis of thrombus through NIR-II imaging and enabling efficient photothermal thrombolysis. This work not only furnishes a NIR-II agent with excellent overall performance but also provides valuable guidance for the design of high-performance NIR-II agents.

Molecularly Engineered Multifunctional Bridging Layer Derived from Dithiafulavene Capped Spiroxanthene for Stable and Efficient Perovskite Solar Cells.

This study introduces a novel approach centered around the design and synthesis of an interfacial passivating layer in perovskite solar cells (PSCs). This architectural innovation is realized through the development of a specialized material, termed dithiafulvene end-capped Spiro[fluorene-9,9'-xanthene], denoted by the acronym AF32. In this design architecture, dithiafulvene is thoughtfully attached to the spiroxanthene fluorene core with phenothiazine as the spacer unit, possessing multiple alkyl chains. AF32 passivates interfacial defects by coordinating the sulfur constituents of the phenothiazine and dithiafulvene frameworks to the uncoordinated Pb2+ cations on the surface of the perovskite film, and the alkyl chains construct a hydrophobic environment, preventing moisture from entering the hydrophilic perovskite layer and improving the long-term stability of PSCs. Furthermore, this conductive interlayer facilitates hole transport in PSCs due to its well-aligned molecular orbital levels. Such improvements translated into an enhanced power conversion efficiency (PCE) of 22.6% for the device employing 1.5 mg/mL AF32, and it maintained 85% of its initial PCE after more than 1800 h under ambient conditions [illumination and 45 ± 5% relative humidity (RH)]. This study not only marks progress in photovoltaic technology but also expands our understanding of manipulating interfacial properties for optimized device performance and stability.

Lysozyme aggregation and unfolding in ionic liquid solvents: Insights from small angle X-ray scattering and high throughput screening

Understanding protein behaviour is crucial for developing functional solvent systems. Ionic liquids (ILs) are designer salts with versatile ion combinations, where some suppress unfavourable protein behaviour. This work utilizes small angle X-ray scattering (SAXS) to investigate the size and shape changes of model protein hen egg white lysozyme (HEWL) in 137 IL and salt solutions. Guinier, Kratky, and pair distance distribution analysis were used to evaluate the protein size, shape, and aggregation changes in these solvents. At low IL and salt concentration (1 mol%), HEWL remained monodispersed and globular. Most ILs increased HEWL size compared to buffer, while the nitrate and mesylate anions induced the most significant size increases. IL cation branching, hydroxyl groups, and longer alkyl chains counteracted this size increase. Common salts exhibited specific ion effects, while the IL effect varied with concentration due to complex ion-pairing. Protein aggregation and unfolding occurred at 10 mol% IL, altering the protein shape, especially for ILs with multiple alkyl chains on the cation, or with a mesylate/nitrate anion. This study highlights the usefulness of adopting a high-throughput SAXS strategy for understanding IL effects on protein behaviour and provides insights on controlling protein aggregation and unfolding with ILs.

Green synthesis and characterization of a wholly bio-based self-healing polyester elastomer and its graphene nanocomposites

A new wholly bio-based polyester elastomer (PEE) was synthesized by one-pot condensation polymerization of a fatty diol and a mixture of a fatty tricarboxylic acid and a fatty dicarboxylic acid, all containing multiple alkyl chains, without the use of any solvent or toxic additive. The elastomer shows excellent resilience with low hysteresis, which could fully recover its original state from 200% strain within 5 s. Owing to strong van der Waals interaction among abundant dangling alkyl chains, the polyester elastomer possesses autonomous self-healing behavior at ambient temperature without any external intervention, capable of restoring 96.8% of its original Young's modulus and 52.1% of its original elongation at break within 10 min. Graphene oxide (GO) reduced and modified by p-phenylenediamine (PPD) was used to improve the mechanical properties of PEE to broaden its applications. By incorporating with low loadings of PPD-reduced GO (P-rGO), the Young's modulus, tensile strength, elongation at break and energy at break of PEE are all enhanced, with 0.5 wt% being the optimal loading. However, the self-healing efficiency is reduced by addition of P-rGO due to the restriction of polymer chains. This type of renewable elastomer and its nanocomposites have potential in a variety of applications.

Novel fluorescence liquid crystals based on thiophene-vinylnitrile Schiff-base derivatives

ABSTRACT This paper reported the first example of thiophene-containing AIE fluorescence liquid crystals. Thiophene-vinylnitrile Schiff-base derivatives 5 with one alkyl chain and 6 with two alkyl chains were prepared conveniently in yields of 86% and 88%, respectively. They exhibited the smectic phases from 91.5 to 130.6℃ for sample 5 and 71.3 to 120.2℃ for sample 6. They displayed excellent fluorescence in aggregated states of solid film and mesophase. The absolute fluorescence quantum yields in solid film were as high as 0.64 for samples 5 and 0.76 for sample 6, respectively. These results suggested thiophene-vinylnitrile Schiff-base derivatives 5 and 6 were excellent fluorescence liquid crystals and the multiple alkyl chains on thiophene-vinylnitrile Schiff-base derivatives were favourable for the low temperature of mesophase and high fluorescence.

On the Mechanism of Alkylammonium Ligands Binding to the Surface of CsPbBr3 Nanocrystals.

CsPbBr3 nanocrystals (NCs) suffer from instabilities caused by the dynamic and labile nature of both the inorganic core and the organic–inorganic interface. Surface ligand engineering thus remains an imminent research topic. In this study, classical molecular dynamics simulations with an explicit solvent are used to gain insights into the inherent binding properties of three different alkylammonium ligands—primary dodecylammonium (DA), secondary didodecylammonium (DDA), and quaternary dimethyldi- dodecylammonium (DMDDA). Our simulations uncover three main factors that govern the effective ligand–substrate interactions: (i) the ability of the head-group to penetrate into the binding pocket, (ii) the strength of head-group interactions with the polar solvent, and (iii) the higher barrier for ligand adsorption/desorption in the case of multiple alkyl chains. The interplay between these factors causes the following order of the binding free energies: DDA < DA ≈ DMDDA, while surface capping with DDA and DMDDA ligands is additionally stabilized by the kinetic barrier. These findings are in agreement with previous experimental observations and with the results of presented ligand-exchange experiments, wherein DDA is found to loosely bind to the CsPbBr3 surface, while DMDDA capping is more stable than capping with the primary oleylammonium ligand. The presented mechanistic understanding of the ligand–NC interactions will aid in the design of cationic ligands that make perovskite NC surfaces more robust.

Wholly Biobased, Highly Stretchable, Hydrophobic, and Self-healing Thermoplastic Elastomer.

Renewable polymers with excellent stretchability and self-healing ability are interesting for a wide range of applications. A novel type of wholly biobased, self-healing, polyamide-based thermoplastic elastomer was synthesized using a fatty dimer acid and a fatty dimer amine, both containing multiple alkyl chains, through facile one-pot condensation polymerization under different polymerization times. The resulting elastomer shows superior stretchability (up to 2286%), high toughness, and excellent shape recovery after being stretched to different strains. This elastomer also displays high room-temperature autonomous self-healing efficiency after fracture and zero water uptake during water immersion. The highly entangled main chain, the multiple dangling chains, the abundant reversible physical bonds, the intermolecular diffusion, and the low ratio of amide to methylene group within the elastomer are responsible for these extraordinary properties. The polymerization time influences the properties of the elastomer. The use of the optimal self-healing thermoplastic elastomer in anticorrosion coating, piezoresistive sensing, and highly stretchable fibers is also demonstrated. The elastomer coating prevents stainless-steel products from corrosion in a salty environment due to its superhydrophobicity. The elastomer serves as a robust flexible substrate for creating self-healing piezoresistive sensors with excellent repeatability and self-healing efficiency. The elastomer fiber yarn can be stretched to 950% of its original length confirming its outstanding stretchability.

The influence of multiple alkyl chains on mesomorphic and photophysical properties of diphenylacrylonitrile liquid crystals

ABSTRACT For the purpose of studying the influence of the number of alkyl chains on mesomorphic and photophysical properties of aggregation-induced emission liquid crystals, the novel diphenylacrylonitrile derivatives 6–9 with 2–5 alkyl chains were prepared in yields of 80%–86%. The studies suggested that the number of alkyl chains influenced greatly on both mesomorphic properties and aggregation-induced emission fluorescence. The four or five alkyl chains on diphenylacrylonitrile liquid crystals were favourable for the ordered hexagonal columnar mesophase. The three or four alkyl chains contributed to high fluorescence. The four alkyl chains on diphenylacrylonitrile derivatives were the optimised number for producing the ordered columnar liquid crystalline phase and high fluorescence.

Novel perylene columnar liquid crystal tuned by azo isomerization on bay-positions

Two azo-perylene derivatives (PBI-AZO-1 and PBI-AZO-2) with two alkyl chains and six alkoxy chains were designed and synthesized in yield of 63% and 49%, respectively. PBI-AZO-1 showed no mesophase but PBI-AZO-2 exhibited ordered hexagonal columnar mesophase based on the favorable effects of multiple alkyl chains. PBI-AZO-1 and PBI-AZO-2 exhibited the cis and trans azo-isomerization under radiation of UV light and the fluorescence quantum yields enhanced remarkably from 0.61 and 0.64 to 0.78 and 0.88, respectively. The ordered hexagonal columnar mesophase of PBI-AZO-2 was destroyed by isomerization due to the influence of asymmetrical mixture of cis and trans isomers. The transformation of liquid crystal/non-liquid crystal of PBI-AZO-2 before and after cis/trans isomerization displayed good reversibility by storing the sample for 15 days at room temperature. This kind of liquid crystallic behavior tuned by azo isomerization was first observed for perylene liquid crystal.

Novel near-infrared fluorescent liquid crystal: Bodipy bearing multiple alkyl chains with columnar mesophase

ABSTRACTBy the typical Knoevenagel condensation of Bodipy with aldehyde derivatives, two novel Bodipy derivatives 3 and 6 with symmetric three and six alkyl chains were designed and prepared. The Bodipy derivative 3 with three alkyl chains showed no mesophase but the Bodipy derivative 6 with six alkyl chains possessed the orderly hexagonal columnar mesophase at room temperature. Both samples 3 and 6 exhibited the near-infrared fluorescence with high fluorescence quantum yields and larger Stokes shifts than their Bodipy precursors. Sample 6 was the first near-infrared fluorescent columnar liquid crystal with Bodipy core. This research presented a good strategy on constructing the near-infrared columnar Bodipy liquid crystal.

Luminescent columnar liquid crystals based on AIE tetraphenylethylene with hydrazone groups bearing multiple alkyl chains

A series of novel tetraphenylethylene aromatic acylhydrazone derivatives 11, 12 and 13 with 4, 8 or 12 alkyl chains were designed and synthesized in yields of 82–85%. Studies on the mesomorphic properties suggested the ordered hexagonal columnar mesophase for compounds 11, 12 and 13. The increase in the number of alkyl chains was favourable for decreasing the phase-transition temperatures and extending the mesophase temperature range. Further, samples 11, 12 and 13 presented an excellent AIE effect. The fluorescence intensities increased by 70, 84 and 43 times for samples 11, 12 and 13, respectively. The absolute fluorescence quantum yields were 18.7%, 27.4% and 23.8% in solid films at room temperature and 6.7%, 24.2% and 17.3% in the mesophase. These results suggested that the number of alkyl chains greatly influenced the fluorescence emission and sample 12 with 8 alkyl chains exhibited the strongest fluorescence emission. Sample 12 also displayed the electroluminescence performance on OLED device.

Perylene liquid crystals with multiple alkyl chains: investigation of the influence of peripheral alkyl chain number on mesomorphic and photophysical properties

Novel perylene liquid crystals with 2, 4 and 6 peripheral alkyl chains or 6, 8 and 10 peripheral alkyl chains at both the imide and bay-positions were investigated.

Evaluating solid phase (micro-) extraction tools to analyze freely ionizable and permanently charged cationic surfactants

Working with and analysis of cationic surfactants can be problematic since aqueous concentrations are difficult to control, both when taking environmental aqueous samples as well as performing laboratory work with spiked concentrations. For a selection of 32 amine based cationic surfactants (including C8- to C18-alkylamines, C14-dialkyldimethylammonium, C8-tetraalkylammonium, benzalkonium and pyridinium compounds), the extraction from aqueous samples was studied in detail. Aqueous concentrations were determined using solid phase extraction (SPE; 3 mL/60 mg Oasis WCX-SPE cartridges) with recoveries of ≥80% for 30 compounds, and ≥90% for 16 compounds. Sorption to glassware was evaluated in 120 mL flasks, 40 mL vials and 1.5 mL autosampler vials, using 15 mM NaCl, where the glass binding of simple primary amines and quaternary ammonium compounds increased with alkyl chain length. Sorption to the outside of pipette tips (≤20% of total amount in solution) when sampling aqueous solutions may interfere with accurate measurements. Polyacrylate solid phase microextraction (PA-SPME) fibers with two coating thicknesses (7 and 35 μm) were tested as potential extraction devices. The uptake kinetics, pH-dependence and influence of ionic strength on sorption to PA fibers were studied. Changing medium from 100 mM Na+ to 10 mM Ca2+ decreases Kfw with one order of magnitude. Results indicate that for PA-SPME neutral amines are absorbed rather than adsorbed, although the exact sorption mechanism remains to be elucidated. Further research remains necessary to establish a definitive applicability domain for PA-SPME. However, results indicate that alkyl chain lengths ≥14 carbon atoms and multiple alkyl chains become problematic. A calibration curve should always be measured together with the samples. In conclusion, it seems that for amine based surfactants PA-SPME does not provide the reliability and reproducibility necessary for precise sorption experiments, specifically for alkyl chain lengths beyond 12 carbon atoms.

DNA Condensation Induced by a Star-Shaped Hexameric Cationic Surfactant.

The interactions between a star-shaped hexameric cationic quaternary ammonium surfactant PAHB and calf thymus DNA and induced DNA condensation were investigated by ζ-potential, dynamic light scattering, atomic force microscopy, isothermal titration calorimetry, ethidium bromide exclusion assay, circular dichroism, and cytotoxicity assay. With the addition of PAHB, long extended DNA molecules exhibit successive conformational transitions from elongated coil to a partially condensed cluster-like aggregate, to a globules-on-a-string structure, and then to a fully condensed globule until the saturation point of interaction between PAHB and DNA, which is slightly above their charge neutralization point. The efficient condensation is mainly produced by the strong attractive electrostatic interaction between the multiple positively charged headgroups of PAHB and negatively charged phosphate groups of DNA, and the hydrophobic interaction among the multiple alkyl chains of PAHB. Moreover the transition of the DNA conformation is also affected by the transitions of PAHB molecular conformation from star-shaped to claw-like and pyramid-like. Although the DNA conformation is significantly changed by PAHB, the DNA secondary structure does not display obvious variations, and the PAHB/DNA mixture does not show cytotoxicity when DNA is partially condensed. These results indicate that star-shaped oligomeric cationic surfactant is a potential condensing agent for gene transfection.

Which Molecular Features Affect the Intrinsic Hepatic Clearance Rate of Ionizable Organic Chemicals in Fish?

Greater knowledge of biotransformation rates for ionizable organic compounds (IOCs) in fish is required to properly assess the bioaccumulation potential of many environmentally relevant contaminants. In this study, we measured in vitro hepatic clearance rates for 50 IOCs using a pooled batch of liver S9 fractions isolated from rainbow trout (Oncorhynchus mykiss). The IOCs included four types of strongly ionized acids (carboxylates, phenolates, sulfonates, and sulfates), three types of strongly ionized bases (primary, secondary, tertiary amines), and a pair of quaternary ammonium compounds (QACs). Included in this test set were several surfactants and a series of beta-blockers. For linear alkyl chain IOC analogues, biotransformation enzymes appeared to act directly on the charged terminal group, with the highest clearance rates for tertiary amines and sulfates and no clearance of QACs. Clearance rates for C12-IOCs were higher than those for C8-IOC analogues. Several analogue series with multiple alkyl chains, branched alkyl chains, aromatic rings, and nonaromatic rings were evaluated. The likelihood of multiple reaction pathways made it difficult to relate all differences in clearance to specific molecular features the tested IOCs. Future analysis of primary metabolites in the S9 assay is recommended to further elucidate biotransformation pathways for IOCs in fish.

ChemInform Abstract: Supramolecular Organogels Based on Dendrons and Dendrimers

AbstractReview: [93 refs.

Supramolecular organogels based on perylenetetracarboxylic diimide trimers linked with benzenetricarboxylate

Two new perylenetetracarboxylic diimide (PDI) derivatives, namely, trimer 1 and trimer 2, composed of three PDI units with different tail groups, are prepared. Solubility of these two trimers is significantly different due to the different tail groups. The aggregation behavior of these two compounds in solution was investigated using absorption and fluorescence spectra. The results indicate that both trimers 1 and 2 can form large molecular aggregates via an intermolecular process in either good solvent or poor solvent. Trimer 1 can form gel in a mixed solvent of methanol and tetrahydrofuran (THF), while trimer 2 can only form gel in non-polar solvents, such as hexane and toluene. This can be ascribed to the multiple long alkyl chains in trimer 2, which have introduced extra hydrophobic interactions besides the π–π interactions between the molecules of trimer 2. The morphology examination of the dried gel of trimer 1 by atomic force microscopy (AFM) reveals simply long fibers. But, the dried gel of timer 2 shows network-like morphology, which can be ascribed to the hydrophobic interactions between the multiple alkyl chains.

Unique Solution Properties of Quaternized Oligomeric Surfactants Derived from Ethylenediamine or G0 Poly (amidoamine) Dendrimers

New quaternized oligomeric surfactants containing 4 or 8 alkyl chains were synthesized using ethylenediamine or poly(amidoamine) dendrimers as the central scaffold. Electrical conductivity, surface tension, and pyrene fluorescence measurements, as well as dynamic light scattering were used to characterize their properties. In addition, the dependence of these properties on the alkyl chain length, number of chains, and dendrimer generation was determined through comparison with previously reported oligomeric surfactants. The relation between surface tension and concentration for the oligomeric surfactants exhibited clear breakpoints, which reflect the critical micelle concentration (cmc). Both cmc and surface tension were lower than those of monomeric alkyltrimethylammonium bromide surfactants, indicating that the synthesized oligomeric surfactants have excellent micelle-forming ability in solution and high adsorption ability at the air/water interface, in spite of the large bulky structure containing multiple alkyl chains and headgroups within one molecule. When the alkyl chain length or the number of chains of the oligomeric surfactants was increased, a unique behavior was observed in that adsorption at the air/water interface and solution aggregation occurred simultaneously at a concentration below cmc (as determined by the surface tension method). This suggests that aggregate formation occurs readily in solution along with the adsorption at the interface because of strong attractive interactions between multiple alkyl chains.

Nanostructured Protic Ionic Liquids Retain Nanoscale Features in Aqueous Solution While Precursor Brønsted Acids and Bases Exhibit Different Behavior

Small- and wide-angle X-ray scattering (SWAXS) has been used to investigate the effect that water has on the nanoscale structure of protic ionic liquids (PILs) along with their precursor Brønsted acids and bases. The series of PILs consisted of primary, secondary, and tertiary alkylammonium cations in conjunction with formate, nitrate, or glycolate anions. Significant differences were observed for these systems. The nanoscale aggregates present in neat protic ionic liquids were shown to be stable in size on dilution to high concentrations of water, indicating that the water is localized in the ionic region and has little effect on the nonpolar domains. The Brønsted acid-water solutions did not display nanostructure at any water concentration. Primary amine Brønsted bases formed aggregates in water, which generally displayed characteristics of poorly structured microemulsions or a form of bicontinuous phase. Exceptions were butyl- and pentylamine with high water concentrations, for which the SWAXS patterns fitted well to the Teubner-Strey model for microemulsions. Brønsted base amines containing multiple alkyl chains or hydroxyl groups did not display nanostructure at any water concentration. IR spectroscopy was used to investigate the nature of water in the various solutions. For low PIL concentrations, the water was predominately present as bulk water for PIL molar fractions less than 0.4-0.5. At high PIL concentrations, in addition to the bulk water, there was a significant proportion of perturbed water, which is water influenced in some way by the cations and anions. The molecular state of the water in the studied amines was predominately present as bulk water, with smaller contributions from perturbed water than was seen in the PILs.

Self-Assembling Peptides: Implications for Patenting in Drug Delivery and Tissue Engineering

In this paper, a comprehensive review of recent patents concerning the molecular self-assembly of peptides, peptide amphiphiles and peptidomimetics into molecules through nanoarchitectures to hydrogels is provided. Their potential applications in the field of drug delivery and tissue engineering have been highlighted. The design rules of this rapidly growing field are centered mainly on the construction of peptides in the form of peptide amphiphiles, aromatic short peptide derivatives, all-amino acid peptide amphiphiles, lipidated peptides with single and multiple alkyl chains and peptide-based block copolymers and polymer peptide conjugates. The interest in patenting of self-assembling peptides is also driven by their type (I, II, III and IV) and their ability to form well-regulated highly-ordered structures such as β-sheets/β-hairpins, α-helices/coiled coils and to hierarchically self-organize into supra-molecular structures. The applicability of these systems in cell culture scaffolds for tissue engineering, drug and gene delivery and as templates for nanofabrication and biomineralization has inspired various groups over the globe. This resulted in development of self-assembling peptides as synthetic replacements of biological tissues, designing materials for specific medical applications, and materials for new applications such as diagnostic technologies. Furthermore, biologically derived and commercially available systems are also discussed herein along with a brief account of various awarded and pending patents in the past 10 years. An overview of the diversity of the patent applications is also provided for self-assembling systems based on nano- and/or micro-scale such as fibers, fibrils, gels, hydrogels, vesicles, particles, micelles, bilayers and scaffolds.