Increasing Length Of Alkyl Side Chain Research Articles

Cross-Reactivity of 24 Cannabinoids and Metabolites in blood using the immunalysis cannabinoids direct enzyme-linked immunosorbent assay kit.

With a wider availability of synthetic and semi-synthetic cannabinoids in the consumer space, there is a growing impact on public health and safety. Forensic toxicology laboratories should keep these compounds in mind as they attempt to remain effective in screening for potential sources of human performance impairment. Enzyme-linked immunosorbent assay (ELISA) is a commonly utilized tool in forensic toxicology, as its efficiency and sensitivity make it useful for rapid and easy screening for a large number of drugs. This screening technique has lower specificity, which allows for broad cross-reactivity among structurally-similar compounds. In this study, the Cannabinoids Direct ELISA kit from Immunalysis was utilized to assess the cross-reactivities of 24 cannabinoids and metabolites in whole blood. The assay was calibrated with 5 ng/mL of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol and the analytes of interest were evaluated at concentrations ranging from 5 to 500 ng/mL. Most parent compounds demonstrated cross-reactivity ≥ 20 ng/mL, with increasing alkyl side chain length relative to Δ9-tetrahydrocannabinol resulting in decreased cross-reactivity. Of the 24 analytes, only the carboxylic acid metabolites, 11-nor-9-carboxy-Δ8-tetrahydrocannabinol, 11-nor-9(R)-carboxy-hexahydrocannabinol, and 11-nor-9(S)-carboxy-hexahydrocannabinol, were cross-reactive at levels ≤ 10 ng/mL. Interestingly, 11-nor-9(R)-carboxy-hexahydrocannabinol demonstrated cross-reactivity at 5 ng/mL, where its stereoisomer 11-nor-9(S)-carboxy-hexahydrocannabinol, did not. As more information emerges about the prevalence of these analytes in blood specimens, it is important to understand and characterize their impact on current testing paradigms.

First determination of elevated levels of plastic additives in finless porpoises from the South China Sea

Plastic additives, such as organophosphate esters (OPEs) and phthalate esters (PAEs), are raising public concerns due to their widespread presence and potential health risks. Nonetheless, the occurrences and potential health risks of these additives in marine mammals remain limited. Here, we first investigated the accumulation patterns and potential risks of OPEs and metabolites of PAEs (mPAEs) in Indo-Pacific finless porpoises inhabiting the northern South China Sea (NSCS) during 2007–2020. The average hepatic concentrations of ∑15OPEs and ∑16mPAEs in the NSCS finless porpoises were 53.9 ± 40.7 and 98.6 ± 54.8 ng/g ww, respectively. The accumulation of mPAEs and OPEs in the finless porpoises is associated with the chemical structures of the compounds. ∑5halogenated-OPEs were the most dominant category (62.6%) of ∑15OPEs, followed by ∑6aryl-OPEs (25.9%) and ∑6nonhalogenated alkyl-OPEs (11.5%). The accumulation of mPAEs displayed a declining trend with increasing alkyl side chain length (C0-C10). Although the hepatic burden of mPAEs in finless porpoises was sex-independent, some OPEs, including TDCIPP, TBOEP, TCIPP, TCrP, TPHP, and TDBPP, exhibited significantly higher concentrations in adult males than in adult females. TDBPP, as a new-generation OPE, exhibited a gradual increase during the study period, suggesting that TDBPP should be prioritized for monitoring in the coastal regions of South China. The estimated hazard quotient indicated that almost all mPAEs and OPEs pose no hazard to finless porpoises, with only DEHP presenting potential health risks to both adult and juvenile finless porpoises.

Effects of alkyl side-chain length on binding with bovine serum albumin, cytotoxicity, and antibacterial properties of 1-alkyl-3-methylimidazolium dicyanamide ionic liquids

In this study, the behavior of 1-alkyl-3-methylimidazolium dicyanamide ionic liquids (ILs) with ethyl, butyl, hexyl, octyl, and decyl side-chains was evaluated to gain a deeper insight into the potential hazards posed by ILs to the environment and organisms. The effects of the alkyl side-chain length on the interactions between the ILs and bovine serum albumin (BSA), the cytotoxicity and antibacterial performance of the ILs was evaluated. The BSA binding ability of the ILs increased with increasing alkyl side-chain length, and the binding constants of the ILs increased from 1.80 L/mol for 1-ethyl-3-methylimidazolium dicyanamide to 196 L/mol for 1-decyl-3-methylimidazolium dicyanamide. IL binding with BSA was a spontaneous process initiated by hydrophobic forces. This was confirmed using circular dichroism spectra, dynamic light scattering measurements and molecular docking simulations. The results of the cytotoxicity and antimicrobial activity of ILs demonstrated that the increase in alkyl side-chain length increased IL toxicity. The effects of the alkyl side-chain length of 1-alkyl-3-methylimidazolium tetrafluoroborate ILs on the interactions between ILs and BSA and cytotoxicity of the ILs were also evaluated. Furthermore, we demonstrated that tetrafluoroborate-based ILs were more toxic than dicyanamide-based ILs. Herein, we thoroughly describe the effects of the alkyl side-chain length on the properties of ILs and provide background information for future studies on the properties of carbon dots fabricated using ILs as precursors.

Morphological and Interaction Characteristics of Surface-Active Ionic Liquids and Palmitic Acid in Mixed Monolayers.

A series of water soluble, surface-active ionic liquids (SAILs), namely, 1-alkyl-3-methyl imidazolium chlorides ([Cn -mim]Cl) and their mixtures with palmitic acid (PA) are investigated in Langmuir monolayers and Langmuir-Blodgett films. It is inferred from the surface pressure-area isotherms that C16 -mim-IL mixes non-ideally with PA and stabilizes the binary mixed films. In addition, the residence of mim-IL at the water surface is enhanced as a function of the increasing alkyl side chain length. Generally, the compressional moduli values decrease upon increasing the content of the mim-ILs over a wide range of compositions. Furthermore, film relaxation measurements indicate that the IL component is selectively excluded from the mixed films upon achieving a certain target pressure. Brewster angle microscope images demonstrate minimal changes on the PA domains in the presence of either C4 - and C8 -mim-ILs, whereas presence of the hexadecyl counterpart results in the formation of condensed sheets. Atomic force microscopy imaging of deposited films show the formation of propeller-like aggregates when C8 - or C16 -mim-IL is present in the mixed films.

Evaluation of the surface properties of poly(ionic liquid) materials by inverse gas chromatography

Inverse gas chromatography (IGC) was used as a tool to evaluate the surface parameters of three poly(1-alkyl-3-vinylimidazolium hexafluorophosphate) (P[CnVIM][PF6], n = 2, 4, 6) materials that were obtained by a free-radical polymerization. IGC characterization was carried out at temperatures ranging between 303.15 and 343.15 K for determining the dispersive free energy (γsd) as well as the Lewis acidity and basicity parameters of the three materials. The retention behaviour of the probes on the surfaces of the three materials was analysed by plotting the net retention volumes (Vn) of the probes as a function of temperature. The dispersive free energy results revealed that all three materials have high γsd values and that the γsd value decreases in an almost linear fashion with increasing temperature. The acid-base data for the three materials confirmed that the surfaces of all three materials can be considered to be amphoteric with a predominantly basic character and that the basicity decreases with increasing alkyl side chain length on the imidazolium backbone.

Evidence of a reverse side-chain effect of tris(pentafluoroethyl)trifluorophosphate [FAP]-based ionic liquids against pathogenic bacteria

Increased interest in ionic liquids (ILs) is due to their designable and tunable unique physicochemical properties, which are utilized for a wide variety of chemical and biotechnological applications. ILs containing the tris(pentafluoroethyl)trifluorophosphate ([FAP]) anion have been shown to have excellent hydrolytic, electrochemical and thermal stability and have been successfully used in various applications. In the present study the influence of the cation on the toxicity of the [FAP] anion was investigated. Due to the properties of [FAP] ILs, the IL-toxicity of seven cations with [FAP] compared to [Cl] was examined by determination of minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) on six Gram-positive and six Gram-negative clinically-relevant bacteria. For the first time, to our knowledge, the results provide evidence for a decrease in toxicity with increasing alkyl side-chain length, indicating that the combination of both ions is responsible for this ‘reverse side-chain effect’. These findings could portend development of new non-toxic ILs as green alternatives to conventional organic solvents.

Revisiting the crystallization of poly(2-alkyl-2-oxazoline)s

Poly(2-alkyl-2-oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (Tg) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt-recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 °C and PiPropOx between 90 and 150 °C show that PAOx can crystallize in bulk when enough time is given. The decrease of Tg and the corresponding increase in chain mobility at T > Tg with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 721–729

Correlations between alkyl side chain length and dynamic mechanical properties of poly(n-alkyl acrylates) and poly(n-alkyl methacrylates)

In the present paper, dynamic mechanical properties of poly(n-alkyl acrylates) (PnAA) and poly(n-alkyl methacrylates) (PnAMA) with different alkyl side chain length were studied. The results show that with the increase of alkyl side chain length, the storage modulus changes more steadily, and the loss modulus peak and the tan δ peak become broader for PnAA and PnAMA. At the same time, the tan δ peak is more and more apart from the loss modulus peak and the point where the storage modulus begins to drop. For quantitative discussion, three variables, the steepness index ( S), the transition wideness ( W) of storage modulus and the integration area ( A) of tan δ were defined to investigate the potential correlation between the dynamic mechanical properties and alkyl side chain length. It can be observed that S decreases while W and A increase with increasing alkyl side chain length. Moreover, the relaxation spectra of the two series of polymers are calculated from the corresponding mechanical spectra. The shapes of the relaxation spectra are broader and broader with the increase of the alkyl side chain length. These phenomena are interpreted by the perspective of fragility, molecular packing efficiency and intermolecular coupling.

CAFM on conjugated polymer nanofibers: Capable of assessing one fiber mobility

Poly(3-alkylthiophene) (P3AT) nanofibers (NFs) are interesting as building blocks for future organic electronic devices but also as a model system to examine transport mechanisms in semiconducting polymers. However, due to the technical problem of making good contacts at the nanometer scale, electrical characterizations on one isolated P3AT NF are rare. Here, using Conductive Atomic Force Microscopy (CAFM), charge transport investigations along the length ( π– π stacking direction) and the height (alkyl chain direction) of one single NF are reported. Firstly, by developing a transistor structure with one electrode being the CAFM tip, we measured the longitudinal mobility: μ L = 0.07 ± 0.03 cm 2 V −1 s −1. Secondly, charge transport along the NF height was done in a sandwich structure and led to a transversal mobility of μ T ∼ 10 −5–10 −6 cm 2 V −1 s −1 where μ T was found to decrease with increasing alkyl side chain length. With CAFM charge transport anisotropy in P3AT NF is thus evidenced at the nanometer scale, since we find at least four orders of magnitude difference between μ L and μ T .

Effect of Alkyl Side Chain Length on Relaxation Behaviors in Poly(n-alkyl Acrylates) and Poly(n-alkyl Methacrylates)

Dynamic mechanical analysis (DMA) is used to investigate the effect of alkyl side chain length on the relaxation behavior of poly(n-alkyl acrylates) (PnAA) and poly(n-alkyl methacrylates) (PnAMA) above the glass transition temperature (Tg). Master curves and shift factors (log aT) were obtained using the time–temperature superposition (TTS) principle. The log aT curves of PnAA and PnAMA exhibit a dynamic crossover from one Vogel–Fulcher–Tammann–Hesse (VFTH) equation to another above Tg. The corresponding temperature was designated as the dynamic crossover temperature (Tc). It is found that Tc/Tg and the apparent activation energy (Eg) increases, e whereas the fragility index (m) decreases with increasing alkyl side chain length. Further analysis shows that m ∝ Tg, Eg∝ , and Eg∝ m2 for both PnAA and PnAMA.

AFM Study of Two-Dimensional Epitaxial Arrays of Poly(γ-l-glutamates) with Long n-Alkyl Side Chains on Graphite

Two-dimensional (2D) arrays of poly(γ-n-alkyl l-glutamates) (PGn) on HOPG are found to be formed by casting under conditions producing submonolayer coverage. Direct observation of the arrays in a series of polymers using atomic force microscopy allowed clear visualization of the island structures, which consisted of parallel running rods. The helical polymer chains were epitaxially aligned to form rods with a “head to head” or a “head to tail” association. In the array composed of rods, the extended alkyl side chains with all-trans conformation are divided to both sides of a helical main chain and align perpendicularly to the main chain. The interval distances between parallel rods in the island increased linearly by about 2.2 Å/CH2 unit with increasing alkyl side chain length. Epitaxial adsorption of alkyl chain moieties onto graphite is the primary driving force in the formation of the 2D array structure of these helical polymers.

Aqueous Properties of Resorcinol-type Calix[4]arenes Bearing Four Alkyl Side Chains

The resorcinol-type calix[4]arenes bearing alkyl side chains ([4]Ar-Rn, n = 4, 6, 8) have been prepared, and their aqueous properties at pH 13 have been studied by measuring the surface tension, NMR, and solubilization behavior of benzene. It is found from the surface tension measurements that the formation of micelles is promoted and the surface tension value at the critical micelle concentration cmc is decreased with increasing alkyl side chain length. The results of 2D-NMR and relaxation measurements suggest that the interaction of alkyl side chains in the micelles becomes weak, but the interaction between the resorcinol ring and the inner alkyl side group is increased with increasing alkyl side chain length. In the solubilization of benzene, benzene molecules are mainly incorporated in the resorcinol ring part of [4]Ar-R4, whereas they are solubilized in the alkyl side chains of [4]Ar-R6.

Catalytic Hydrocracking Reaction Pathways, Kinetics, and Mechanisms of n-Alkylbenzenes

The hydrocracking reaction pathways and kinetics of alkyl aromatic structural elements present in typical petroleum feedstocks were probed through experiments at 350°C and 1000 psig of hydrogen pressure with a Shell NiW/USY zeolite catalyst. Experimental results for C4-C15 alkylbenzenes provided insight into their respective alkane-like and aromatic-like character, as well as the effect of side-chain length on the kinetics and product selectivities. Initial product selectivities indicated that the expected prototypical ring dealkylation to benzene was accompanied by other significant reactions. Reactions in the side chain produced various shorter-chain alkylbenzenes, including toluene. Ring closure of the side chain was also significant, producing hydroaromatic bicyclic compounds. The overall reaction rate was first order and generally increased with increasing alkyl side-chain length.

Surface characteristics of polysulfoalkyl methacrylates

Coated hydroxyethyl methacrylate-sodium sulfoalkyl methacrylate copolymer films were surface characterized. The contact angle hysteresis increases and the receding angle decreases with increasing alkyl side-chain length, while the advancing angle decreases with hydration time. It was found that the buoyancy slopes of the advancing ( r a) and receding ( r r) process determined by the Wilhelmy plate method were not parallel. The ratio of r a to r r was greater than 1, and increases with the alkyl side-chain length and the hydration time, contrary to that of polyhydroxyethyl methacrylate, where r a r r was less than 1. The slope ratio would be suppressed in solution with added salt, revealing that the reorientation and expansion of the polymer chain in water is being suppressed. X-ray photoelectron spectroscopy (XPS) analysis of the surface of these copolymers showed a striking enrichment of the sulfonate groups in the surface. The zeta potential was between −40 and −50 mV as measured by the streaming potential method. During dehydration, along with a decrease in sulfur and sodium concentration in the surface, the carbon 1s peak at the high binding energy decreased and the alkyl carbon main peak increased. The surface tension of aqueous solutions of sulfoalkyl methacrylate monomers and homopolymers decreases with increasing alkyl side-chain length, which may contribute to the decrease in water-polymer film interfacial tension and thus the increase in the slope ratio.

Uptake of Homologous Series of P-n-Alkylphenols by Phytopathogenic Fungi

Uptake of homologous series of p-n-alkylphenols by fungi from aqueous phase was studied using spores of Piricularia oryzae and Gibberella fujikuroi, and mycelia of P. oryzae as test organisms. Process of uptake seemed to be physical, because dead cells took up as much phenol as did living cells. Amount of phenol taken up by fungal cells equilibrated with concentration of remaining phenol in external aqueous phase. Uptake was found to increase with increasing alkyl side chain length, and solubility of the homologous series decreases at higher rate than uptake increases. Uptake of higher homologue is not supposed to reach the level enough to inhibit growth of fungi, on account of its slight solubility. These results explain the reason why antifungal activity of p-n-alkylphenol increases with increasing alkyl chain length up to a certain homologue, and decreases for the higher members.