Alkyl Length Research Articles

Azopolyesters with Intrinsic Crystallinity and Photoswitchable Reversible Solid‐to‐Liquid Transitions

AbstractHerein, we introduce a variety of azopolyesters (azobenzene‐based polyesters) with remarkable intrinsic crystallinity and photoinduced reversible solid‐to‐liquid transition abilities from copolymerization of azobenzene‐based epoxides with cyclic anhydrides. The length of the soft alkyl side‐chain inlaid with azobenzenes and stereoregularity of main‐chain of azopolymers have tremendous effects on crystallization properties of the resulting polyesters with melting temperature (Tm) in the range of 51–251 °C. Moreover, some of azopolyesters possess excellently photoinduced reversible solid‐to‐liquid transition performance thanks to trans‐cis photoisomerization of azobenzenes. Trans‐azopolyesters are yellow solids with Tms or glass transition temperatures (Tgs) above room temperature, whereas cis‐polymers are red liquids with Tgs below −20 °C. These azopolyesters could be applied as novel light‐switchable adhesives for quartz/quartz, wood/wood and quartz/wood adhesion, with the strength in the range of 0.73–0.89 MPa for trans‐polymers. Conversely, the adhesion strength of liquefied cis‐azopolyesters generated from the irradiation of trans‐polymers by UV light was about 0.1 MPa, which shows light enable to control the adhesion process with high spatiotemporal resolution.

Achieving Ultralong Room-Temperature Phosphorescence in Two-Dimensional Metal Halide Perovskites by Alkyl Chain Engineering.

Two-dimensional (2D) metal halide perovskites with highly efficient ultralong room-temperature phosphorescence (URTP) are rare due to their uncertain structures and complicated intermolecular interactions. Herein, by varying the alkyl length of organic units, we synthesized two single-component 2D metal hybrid perovskites, i.e., B-MACC and B-EACC, with obvious URTP emission. In particular, B-EACC exhibits a green-yellow URTP emission with an ultralong lifetime (579 ms) and a high efficiency (14.86%). It is found that the molecular packing of B-EA+ cations because of the presence one more carbon in the alkyl chain affords strong hydrogen bonding and π-π stacking interactions, which immobilizes and reduces the triplet exciton quenching. Moreover, B-MACC and B-EACC with space-time dual-resolved characteristics can be utilized for dynamic information encryption and optical logic gate applications. This study is the first to disclose the relation between the characteristics of molecular packing and the resultant URTP of 2D metal hybrid perovskites, significantly advancing the development of next-generation URTP materials for versatile applications.

Employing phosphorylated betaines as kinetic hydrate promoters for gas storage application

Pursuing an effective promoter of gas hydrate formation remains a relevant issue in the potential development of solidified natural gas technology. The promoting ability of isopropyl [(N-alkyl-N,N-dimethylammonio)methyl]-phosphonate betaines was assessed using rocking cells equipment. The results reveal that the varying alkyl length makes it possible to accelerate either the nucleation or the growth of model natural gas hydrate.

Dissipative Particle Dynamics-Based Simulation of the Effect of Asphaltene Structure on Oil-Water Interface Properties.

Asphaltenes are the main substances that stabilize emulsions during the production, processing, and transport of crude oil. The purpose of this research is to investigate the process of asphaltenes forming interfacial films at the oil-water interface by means of dissipative particle dynamics (DPD) and the effect of asphaltenes of different structures on the oil-water interface during the formation of interfacial film. It is demonstrated that the thickness of the interfacial film formed at the oil-water interface gradually increases as the asphaltene concentration rises and the amount of asphaltene adsorbed at the oil-water interface gradually multiplies. Both the number and type of heteroatoms in asphaltenes affect the interfacial behavior of asphaltenes. The interface activity of asphaltenes can be enhanced by increasing the number of heteroatoms in the asphaltene, and the type of heteroatom affects as well the interfacial activity of the asphaltene as it affects the aggregation behavior of the asphaltene in the system. As the number of asphaltene aromatic rings increases, the oil-water interfacial tension (IFT) trends down gradually, while the effect of alkyl side chains on the reduction of IFT of asphaltenes is different, and asphaltenes with medium length alkyl side chains can reduce IFT more efficiently.

Cabazitaxel prodrug nanoassemblies with branched chain modifications: Narrowing the gap between efficacy and safety

The clinical application of cabazitaxel (CTX) is restricted by severe dose-related toxicity, failing to considering therapeutic efficacy and safety together. Self-assembled prodrugs promote new drug delivery paradigms as they can self-deliver and self-formulate. However, the current studies mainly focused on the use of straight chains to construct self-assembled prodrugs, and the role of branched chains in prodrug nanoassemblies remains to be clarified. In this study, we systematically explored the structure–function relationship of prodrug nanoassemblies using four CTX prodrugs that contained branched chain aliphatic alcohols (BAs) with different alkyl lengths. Overall, CTX-SS-BA20 NPs with the proper alkyl length exhibited significant improvements in both antitumor efficacy and biosafety. Furthermore, compared with straight chain (SC) modified prodrug nanoassemblies (CTX-SS-SC20 NPs), CTX-SS-BA20 NPs still hold great therapeutic promise due to its good biosafety. These findings illustrated the significance of BAs as modified chains in designing prodrug nanoassemblies for narrowing the efficacy-to-safety gap of cancer therapy.

Helical self-assembly and Fe3+ detection of V-shaped AIE-active chiral tetraphenylbutadiene-based polyamides.

Chiral aggregation-induced emission (AIE) molecules have drawn attention for their helical self-assembly and special optical properties. The helical self-assembly of AIE-active chiral non-linear main-chain polymers would produced some desired optical features. In this work, a series of V-shaped chiral AIE-active polyamides P1-C3, P1-C6, P1-C12 and linear P2-C3, P2-C6, bearing n-propyl/hexyl/dodecyl side-chains, based on tetraphenyl-butadiene (TPB) were prepared. All of the target main-chain polymers exhibit distinct AIE characteristics. The polymer P1-C6 with moderate length alkyl chains shows better AIE properties. The V-shaped main-chains and the chiral induction of (1R,2R)-(+)-1,2-cyclohexanediamine in each repeatingunit promote the polymer chains display helical conformations, and multiple helical polymer chains induce nano-fibers helicity when the polymer chains aggregate and self-assemble in THF/H2O mixtures. Simultaneously, the helical conformation polymer chains and helical nano-fibers cause P1-C6 produce strong CD signals with positive Cotton effect. Moreover, P1-C6 could also occur fluorescence quenching response to Fe3+ selectively with a low detection limit of 3.48 μmol/L.

Flexible Modulation of Cellular Activities with Cationic Photosensitizers: Insights of Alkyl Chain Length on Reactive Oxygen Species Antimicrobial Mechanisms.

Cationic photosensitizers have good binding ability with negatively charged bacteria and fungi, exhibiting broad applications potential in antimicrobial photodynamic therapy (aPDT). However, cationic photosensitizers often display unsatisfactory transkingdom selectivity between mammalian cells and pathogens, especially for eukaryotic fungi. It is unclear which biomolecular sites are more efficient for photodynamic damage, owing to the lack of systematic research with the same photosensitizer system. Herein, a series of cationic aggregation-induced emission (AIE) derivatives (CABs) (using berberine (BBR) as the photosensitizers core) with different length alkyl chains are successfully designed and synthesized for flexible modulation of cellular activities. The BBR core can efficiently produce reactive oxygen species (ROS) and achieve high-performance aPDT . Through the precise regulation of alkyl chain length, different bindings, localizations, and photodynamic killing effects of CABs are achieved and investigated systematically among bacteria, fungi, and mammalian cells. It is found that intracellular active substances, not membranes, are more efficient damage sites of aPDT. Moderate length alkyl chains enable CABs to effectively kill Gram-negative bacteria and fungi with light, while still maintaining excellent mammalian cell and blood compatibility. This study is expected to provide systematic theoretical and strategic research guidance for the construction of high-performance cationic photosensitizers with good transkingdom selectivity.

Revisiting to N‐alkylation of multi‐dentate amines ligand for ATRP

AbstractThe ligands role in normal atom transfer radical polymerization (ATRP) is not only for controlling the system but also regulate the rate of polymerization depending the solubility in the reaction media. Solubility of the catalyst/ligand complexes in organic media is of particular importance to attain homogeneous polymerization conditions. The linear multi‐dentate amine ligands with a long aliphatic chain on the nitrogen atoms provide solubility of its metal complexes in organic solvents. However, the increasing length of the alkyl substituents induces steric effects and can alter the redox potential of the metal center. Herein, to understand the effect of alkyl length, we report the synthesis of tri‐, tetra‐dentate linear amine ligands, diethylenetriamine, triethylenetetramine having n‐alkyl halides containing odd carbon chain lengths (C3H7‐, C5H9‐), respectively. Well‐defined polymers were obtained in ATRP of S and MMA using synthesized ligands. Apparently, increasing the alkyl chain length was sufficient to provide homogeneous ATRP medium, which was not achieved with methyl‐substituted ligands (e.g., pentamethyldiethylenetriamine, PMDETA and hexamethyltriethylenetetramine, HMTETA). In combining ATRP results for odd (synthesized) and even carbon number alkylated ligands (literature), linear decreasing trend was observed on apparent rate constant (kpapp) by the increasing the alkyl chain length.

Substituent alkyl-chain-dependent supramolecular chirality, tunable chiroptical property, and dye adsorption in azobenzene-glutamide-amphiphile based hydrogel

Controlling the supramolecular chirality of a self-assembly system by molecular structure design and external stimuli in aqueous solution is significant but challenging. Here, we design and synthesize several glutamide-azobenzene-based amphiphiles with different length alkyl chains. The amphiphiles can form self-assemblies in aqueous solution and show CD signals. As the number of the alkyl chain of amphiphiles increases, the CD signals of the assemblies can be enhanced. However, the long alkyl chains conversely restrict the isomerization of the azobenzene and the corresponding chiroptical property. Moreover, the alkyl length can determine the nanostructure of the assemblies and exert critical influence on the dye adsorption efficiency. This work exhibits some insights into the tunable chiroptical property of the self-assembly by delicate molecular design and external stimuli, and emphasizes the molecular structure can determine the corresponding application.

Indoloindole‐Based Hole Transporting Material for Efficient and Stable Perovskite Solar Cells Exceeding 24% Power Conversion Efficiency

AbstractThe new concept of hole transporting materials (HTMs) has inspired researchers to develop high‐performing and stable perovskite solar cells (PSCs). In particular, small molecular organic semiconductors have been extensively studied for HTM due to their high reproducibility and easy synthesis. In this work, a novel linear‐type series of indoloindole (IDID)‐based hole transporting materials comprising a fluorinated IDID core(IDIDF) and multiple thiophene rings is developed. The structure‐property relationship in the IDIDF derivatives is investigated systematically by changing the alkyl position and length of the backbone. The intrinsic properties of the material are significantly different depending on the alkyl position of inner thiophene ring. The optimized material exhibits improved solubility, favorable molecular packing patterns, and superior hole mobility. The champion PSCs using the optimum molecule, IDIDF2, yield a power conversion efficiency of 23.16% in non‐doped and 24.24% in doped conditions, which represent one of the highest performances in n‐i‐p planar device configuration. For the first time, the IDIDF2‐based PSCs achieve outstanding thermal and moisture stabilities under thermal aging (85 °C) and relative humidity of 85%, respectively, for 1500 h.

Highly ductile, stable, and efficient organic photovoltaic blends enabled by polymerized ladder-type heteroheptacene-based small-molecule acceptors

Although many fully-conjugated polymerized small-molecule acceptors (PSMAs) with high photovoltaic performance have been reported recently, most of them exhibit high stiffness and are very brittle, which limits their applications in wearable and stretchable electronics. In this work, we show that PSMAs using ladder-type heteroheptacene-cored SMAs (M-series acceptors) as the main building blocks can achieve high mechanical ductility while maintaining high power conversion efficiencies (PCEs). To finely tune molecular stacking and miscibility of the resulting PSMAs (PQ-HD and PQ-OD), two pendant groups with different alkyl lengths (namely, 2-hexyldecyl and 2-octyldodecyl) are anchored on their backbones. With the shorter side-chains, a more intermixed bulk-heterojunction blend morphology as well as highly well-ordered molecular packing are achieved, leading to simultaneous enhancement of both photovoltaic and mechanical properties. The best-performing PSC based on PQ-HD with 2-hexyldecyl side-chains shows a high PCE of 13.36% and excellent mechanical stretchability with a crack-onset strain (COS) of 17.5%, both of which are superior to that based on PQ-OD with 2-octyldodecyl side-chains (PCE = 10.87% and COS = 12.8%). Moreover, the PQ-HD-based PSC also exhibits excellent thermal stability. These outstanding properties in combination with its low synthetic complexity shall make PQ-HD a promising candidate for future applications in flexible and wearable devices.

Detergent headgroups control TolC folding in vitro

TolC is the trimeric outer membrane component of the efflux pump system in Escherichia coli that is responsible for antibiotic efflux from bacterial cells. Overexpression of efflux pumps has been reported to decrease susceptibility to antibiotics in a variety of bacterial pathogens. Reliable production of membrane proteins allows for the biophysical and structural characterization needed to better understand efflux and for the development of therapeutics. Preparation of recombinant protein for biochemical/structural studies often involves the production of proteins as inclusion body aggregates from which active proteins are recovered. Here, we find that the in vitro folding of TolC into its functional trimeric state from inclusion bodies is dependent on the headgroup composition of detergent micelles used. Nonionic detergent favors the formation of functional trimeric TolC, whereas zwitterionic detergents induce the formation of a non-native, oligomeric TolC fold. We also find that nonionic detergents with shorter alkyl lengths facilitate TolC folding. It remains to be seen whether the charges in lipid headgroups have similar effects on membrane insertion and folding in biological systems.

Controllably Adjusting the Hydrophobicity of Collagen Fibers for Enhancing the Adsorption Rate, Retention Capacity, and Separation Performance of Flavonoid Aglycones.

Collagen fibers (CFs) were previously used as packing materials for the separation of flavonoids based on hydrogen bond and hydrophobic interactions. However, as for flavonoid aglycones, CFs presented unsatisfactory adsorption capacity and separation efficiency due to the fact that they include limited hydroxyls and phenyls. In order to improve the adsorption capacity and separation efficiency, the hydrophobic modification strategy was employed in this research to enhance the hydrophobic interaction of CF with flavonoid aglycones by using silane coupling agents with different alkyl chains (isobutyl, octyl, and dodecyl). FT-IR analysis, DSC, TG, SEM, EDS mapping, water contact angle, and absorption time of solvent proved the successful grafting of alkyl chains on the CF without disturbing its special fiber structure, leading to the significantly enhanced hydrophobicity of the CF. The dynamic adsorption and elution behavior of kaempferol and quercetin (the typical flavonoid aglycones) on the hydrophobic CF showed that the adsorption rate and retention rate were largely increased in comparison with the CF without modification. Molecular dynamic simulations indicated that the CF grafted with isobutyls could interact with flavonoid aglycones through the highest synergetic effect of hydrophobic and hydrogen bond interactions, which exhibited the strongest retention to flavonoid aglycones. On further increasing the alkyl length (octyl and dodecyl), the hydrophobic interaction was further enhanced, but the hydrogen bonds were significantly weakened by steric hindrance, which showed that the retention to flavonoid aglycones was appropriately increased but without causing peak tailing. In the column separation of kaempferol and quercetin, the CF with hydrophobic modification presented a greater separation efficiency, with the purity of kaempferol increased from 71.99 to 86.57-97.50% and the purity of quercetin increased from 82.69 to 88.07-99.37%, which was much better than that of polyamide and close to that of sephadex LH 20. Therefore, the hydrophobicity of the CF could be controllably adjusted to enhance the adsorption rate and retention capacity, specifically improving the separation efficiency of flavonoid aglycones.

Extending the Library of 4‐Hydroxycoumarin Derivatives with Potential Pharmacological Activity by a Catalyst‐Free and Purification‐Free Method

AbstractConstant mutations of SARS‐CoV‐2 from 2019 to the present commences potential dilemma to the efficacy of developed COVID‐19 antiviral drugs. In this current report, series of 3‐phenyl(alkylamino)methyl‐4‐hydroxycoumarin was identified as compounds of drug‐likeliness that, through molecular docking simulations, also demonstrated favourable binding to different sites of the SARS‐CoV‐2 RBD/hACE2 complex. This was achieved by varying the chain of the alkyl length and the substituent of the phenyl moiety. The subjected 3‐phenyl(alkylamino)methyl‐4‐hydroxycoumarin compounds were successfully synthesized by a catalyst‐free multicomponent condensation reaction of 4‐hydroxycoumarin, p‐substituted benzaldehyde, and linear alkyl amines in dichloromethane (DCM) at 22 °C. The crude products were achieved in a moderate (40–50 %) to a very good (80–90 %) yield with excellent purity without the need for chemical purification verified by nuclear magnetic resonance (NMR) spectroscopy. The simple method to produce 3‐phenyl(alkylamino)methyl‐4‐hydroxycoumarin and the preliminary docking results present an opportunity for advancement in drug discovery.

Introduction of versatile and recyclable network poly (ionic liquid)s as an efficient solvent with desired properties for application in C[sbnd]C cross-coupling reactions

Synthesis of high viscosity, ecofriendly, and low melting point poly(ionic liquid)s (LMP-PIL) with network structure has been introduced by the reaction of 1,1′,1′′‑(1,3,5‑triazine‑2,4,6‑triyl) tris(3‑methyl‑1H‑imidazol‑3‑ium) iodide ionic liquid (TAIm[I] IL) monomer with disodium salts of various open-chain carboxylic acids as well as sulfonic acids via a polycondensation on counter ions (PC-CI). Change in alkyl group length in carboxylate, as well as sulfonate, provide a broad spectrum of properties in terms of viscosity, density, and solubility for the resulting PILs. The physical properties of the PILs including, viscosity, melting point, boiling point, density,M¯n, and polydispersity (Ð), were determined in this study. Also, thermal behavior of the PILs were studied in comparison with the corresponding monomers. The ecofriendly PILs served as an efficient solvent and ligand for the Cu-catalyzed Heck and Sonogashira CC coupling reactions. High to excellent yields were obtained for various coupling products under mild conditions at melting points of the PILs. Also, the coupling products could be obtained with direct scalability. The prepared PILs could be recycled several times from the homogenous reaction mixture with preservation of the intrinsic properties. Also, a detailed study was conducted on the mechanism of the coupling reactions.

Surface and thermodynamics properties of commercial fatty-alcohol ethoxylate surfactants

The present study provides the surface and thermodynamic properties data of commercial fatty-alcohol ethoxylate surfactants (FAEs) at different temperatures (25–60 °C). These compounds are a mixture of fatty-alcohol ethoxylate oligomers with different degree of ethoxylation (2.6–11) and length of the alkyl chain (C10-C18). In this work, we analyzed determinate the water content by the Karl-Fisher method and measured the surface tension using the Wilhelmy plate method. In addition, we studied the effect of their structural parameters (degree of ethoxylation and length of alkyl chain) and the temperature on the changes of the thermodynamic functions (Gibbs free energy, enthalpy, and entropy) for the processes of adsorption and micellization. It was found an exponential decrease of the critical micellar concentration (CMC) in molar scale with the length alkyl chain of the fatty-alcohol ethoxylate surfactants, and the CMC values and thermodynamic parameters agree with those values found in literature for pure compounds. Moreover, the micellization entropy increases with the degree of ethoxylation of the surfactant.

Insight into the stabilization mechanism of imidazole-based ionic liquids at the interface of the carbon nanotubes: A computational study

Ab initio calculations have been performed to systematically investigate the structures, binding energies, vibrational spectra, as well as the non-covalent interactions of imidazolium-based ionic liquids (ILs) at the interface of carbon nanotubes (CNTs). The effects of alkyl length of imidazolium cations, types of anions as well as diameters of CNTs on the relevant interfacial structures and properties have been explored in this study. Our calculations demonstrated that the interfacial imidazolium cations display two different orientations (cations paralleling and perpendicular to the CNTs surface) irrespective of the alkyl chain length of cations, types of anions and the diameters of CNTs. By comparison with the calculated binding energies between cations and the CNTs, the cations paralleling to the CNTs surface are thermodynamically much more stable due to the significant interfacial π-π stacking interactions. In addition, our results indicated that there is significantly difference for the infrared (IR) spectra of the imidazolium cations (between two orientations) on the CNTs surface. Therefore, with the IR spectra, the specific orientations of imidazolium cations on surface of CNTs can be better understood. Moreover, interaction region indicator (IRI) as well as symmetry-adapted perturbation theory (SAPT) analysis were employed to deep understanding of the non-covalent interactions between imidazolium-based ILs and CNTs. Our calculations explore that the paralleling cations is stabilized on the CNTs surface by the dispersion (especially for the π-π stacking) interactions. However, for the cations perpendicular to the CNTs surface, electrostatic, induction as well as the dispersion interactions are all very important. Our calculated results provide a molecular level understanding the stabilization mechanism of imidazole-based ILs at the interface of the CNTs and will be a bit favorable to clarify the existing debate on the stabilization mechanism from various experimental observations.

Hydrolysis-oxidation of cellulose to formic acid in the presence of micellar vanadium-containing molybdophosphoric heteropoly acids

OxFA-processing of inedible cellulose is considered as a perspective way for the production of biogenic formic acid (FA) which appeared to be a promising source for sustainable energy. In our work, the one-pot hydrolysis-oxidation of cellulose to FA was studied in the presence of the micellar acidic catalysts based on Mo–V–P heteropoly acids [Cn-MIM]y/H3+x-yPMo12-xVx (n = 6, 10 and 16; x = 1, 2 and 4; y = 2–6). The influence of amount of V, substitution of H+ by [Cn-MIM] and the length of alkyl group Cn of the cation was revealed. The optimization of the reaction conditions was also performed. To our knowledge, heterogeneous catalysts of such a composition were applied in cellulose hydrolysis-oxidation to FA for the first time. In the presence of C10-MIM/HPMo11V catalyst, the optimal reaction conditions were determined: 10 g/L of cellulose, 1.25–10 g/L of catalyst, 5 MPa of gas mixture (O2/N2 - 20/80 vol/vol) and 170–180 °C. Decreasing the alkyl group length of Cn-MIM+ cation or V content into framework of heteropoly anion were revealed to rise up the yield of the target product. These correlations were caused by the following factors. First, the decreasing acidity of micellar catalysts. Senond, the change in distribution of electron density in heteropoly anion due to the interaction between hydrogen atoms of alkyl group of Cn-MIM cation and oxygen atom of heteropoly anion. Third, blocking of V active sites for reagents. Influence of acidity on catalytic properties of micellar catalysts was also revealed in the course of screening samples with the different degree of protons substitution by C16-MIM+. The reaction rate was demonstrated to rise with increasing degree of protons substitution by C16-MIM + cation in C16-MIM/HyPMo11V and C16-MIM/HyPMo8V4 samples. The yield of FA up to 45 mol% can be reached over micellar HPA catalysts studied.

Tuning of scleroglucan adsorption on carbonate surfaces via grafting alkyl side chains of different lengths: a theoretical and experimental study.

The semi-flexible polysaccharide scleroglucan (Sclg) is a well-known viscosity modifier and its highly hydrophilic nature limits its utilization as a polymeric surfactant of high efficiency. Grafting hydrophobic alkyl moieties onto the chain backbone provides a convenient means to reduce the hydrophilicity of Sclg. Herein, by using a self-consistent field theory (SCFT) that considers both the semi-flexibility of the Sclg main chain and the presence of grafted alkyl chains, we study the influences of the grafted alkyl moieties with different lengths (C6, C10 or C18) on the adsorption behaviors of the resultant polymeric surfactants on a carbonate surface. The extended SCFT well predicts the experimentally observed side alkyl-length-, salt- and temperature-enhanced surface excess of the modified Sclgs. The accumulation profiles of the main chains of different modified Sclgs are nearly superimposable under each solution condition. However, increasing the alkyl-length enhances the accumulation of the adsorbed side-chain segments on the surfaces. Polymer/surface entropic repulsion forces and side-chain/surface interactions govern the adsorption behaviors in regions near the surface, while the adsorption behaviors far away from the surface are controlled by the side chain/side chain interactions. On the basis of conformation profiles of the directly adsorbed chains, a model depicting the effects of the alkyl-length on the adsorbed chain conformations is proposed. These combined theoretical/experimental results enable production of advanced bio-polymeric surfactants with wide tunability and high performance.

The influence of terminal alkyl groups on the structure, and electrical and sensing properties of thin films of self-assembling organosilicon derivatives of benzothieno[3,2-b][1]benzothiophene

A correlation between the sensing and electrical properties of monolayer OFETs based on novel organosilicon derivatives of BTBT with different lengths of terminal alkyl groups was revealed.