CH CH2 Research Articles

Five novel palladium(II) complexes of 8-hydroxyquinoline and amino acids with hydrophobic side chains: synthesis, characterization, cytotoxicity, DNA- and BSA-interaction studies

The side effects and resistance of metal-based anticancer drugs prompted us to synthesis a novel series of five Pd(II) complexes of the type [Pd(8-QO)(AA)]; where 8-QO = anion of 8-hydroxyquinoline and AA = anions of amino acids having nonpolar aliphatic side chain such as glycine (–H), alanine (–CH3), valine (–CH(CH3)2), leucine (–CH2–CH(CH3)2) and isoleucine (–CH(CH3)CH2–CH3). The complexes have been characterized with the help of FT-IR, UV–Vis, one and two-dimensional 1H-NMR, elemental analysis and conductivity measurements. On the basis of these characterization data, a four coordinated square planar geometry for all of these complexes have been proposed. The compounds were screened for their in vitro activities against human cancer cell line, MOLT-4 and their 50% inhibition concentration were ascertained by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Since four out of the five newly synthesized compounds were found to be more active than the standard anticancer drug, cisplatin, their detailed interaction with calf thymus DNA (as a target) and bovine serum albumin (BSA) (as a carrier) were also carried out by utilizing absorption spectra, fluorescence spectra and ethidium bromide displacement studies. In these experiments, several binding and thermodynamic parameters were also calculated. These results suggested that hydrogen binding and van der Waals forces play a major role in the interaction between metal complexes with CT-DNA and BSA. Communicated by Ramaswamy H. Sarma

Combinational effect of angiotensin receptor blocker and folic acid therapy on uric acid and creatinine level in hyperhomocysteinemia-associated hypertension.

Homocysteine [HSCH2 CH2 CH(NH2 )COOH] (Hcy) is a sulfur-containing amino acid of 135.18 Da of molecular weight, generated during conversion of methionine to cysteine. If there is a higher accumulation of Hcy in the blood, that is usually above 15µmol/L, it leads to a condition referred to as hyperhomocysteinemia. A meta-analysis of observational study suggested an elevated concentration of Hcy in blood, which is termed as the risk factors leading to ischemic heart disease and stroke. Further experimental studies stated that Hcy can lead to an increase in the proliferation of vascular smooth muscle cells and functional impairment of endothelial cells. The analyses confirmed some of the predictors for Hcy presence, such as serumuric acid (UA), systolic blood pressure, and hematocrit. However, angiotensin-converting enzyme inhibitors angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) alone are inadequate for controlling UA and creatinine level, although the addition of folic acid may be beneficial in hypertensive patients who are known to have a high prevalence of elevated Hcy. We hypothesized that combination therapy with an ARB (olmesartan) and folic acid is a promising treatment for lowering the UA and creatinine level in hyperhomocysteinemia-associated hypertension.

Novel non-toxic high efficient antibacterial azido chitosan derivatives with potential application in food coatings

In this work, we developed a simple method for the preparation of N-(3-azido-2-hydroxypropyl)chitosan. We compared the antibacterial activity of N-(3-azido-2-hydroxypropyl)chitosans and previously synthesized N-(2-azidoethyl)chitosans. N-(3-azido-2-hydroxypropyl)chitosans possess higher antibacterial effect which is comparable with that of ampicillin and gentamicin. The effect is due to azido pharmacophore –CH2–CH(OH)–CH2–N3 (for N-(3-azido-2-hydroxypropyl)chitosan) or –CH2–CH2–N3 (for N-(2-azidoethyl)chitosan) introduced in chitosan chain, since the corresponding organic azides NH2–CH2–CH2–N3 and NH2–CH2–CH2–N3 are characterized by high antibacterial activity. However, high antibacterial organic azides NH2–CH2–CH2–N3 and NH2–CH2–CH2–N3 are characterized by high toxicity. Their conjugation to the chitosan chain saves their antibacterial effect, but strongly diminishes their toxicity, and the toxicity of the resulting derivatives is comparable with that of the starting chitosan. These findings are of interest to food science, since novel effective food coatings can be developed on basis of prepared derivatives.

AuCu Alloy Nanoparticle Embedded Cu Submicrocone Arrays for Selective Conversion of CO2 to Ethanol.

The CO2 reduction reaction (CO2 RR) driven by renewable electricity represents a promising strategy toward alleviating the energy shortage and environmental crisis facing humankind. Cu species, as one type of versatile electrocatalyst for the CO2 RR, attract tremendous research interest. However, for C2 products, ethanol formation is commonly less favored over Cu electrocatalysts. Herein, AuCu alloy nanoparticle embedded Cu submicrocone arrays (AuCu/Cu-SCA) are constructed as an active, selective, and robust electrocatalyst for the CO2 RR. Enhanced selectivity for EtOH is gained, whose Faradaic efficiency (FE) reaches 29 ± 4%, while ethylene formation is relatively inhibited (16 ± 4%) in KHCO3 aqueous solution. The ratio between partial current densities of EtOH and C2 H4 (jEtOH /jC2H4 ) can be tuned in the range from 0.15 ± 0.27 to 1.81 ± 0.55 by varying the Au content of the electrocatalysts. The combined experimental and theoretical calculation results identify the importance of Au in modifying binding energies of key intermediates, such as CH2 CHO*, CH3 CHO*, and CH3 CH2 O*, which consequently modify the activity and selectivity (jEtOH /jC2H4 ) for the CO2 RR. Moreover, AuCu/Cu-SCA also shows high durability with both the current density and FEEtOH being largely maintained for 24 h electrocatalysis.

Spectroscopic imaging of deposition of asphaltenes from crude oil under flow

We demonstrate, for the first time, the application of FTIR spectroscopic imaging approach in situ to monitor the precipitation process of oil asphaltenes, induced by n-heptane under flow using microfluidic devices. The aggregation of asphaltenes induced by n-heptane flow with subsequent precipitation and formation of the deposits was studied for solution containing 5 wt % of asphaltenes in benzene. The FTIR spectroscopic approach with an array detector allowed us to assess the spatial distribution of the chemical components and their amounts in the system and display the process of aggregates formation with a spatial resolution of few micrometres. This chemical imaging technique shows that the flow of heptane results in non-equilibrium condition when the local content of the flocculants reaches the threshold amount needed for the asphaltenes aggregation. The relatively slow process of heptane diffusion into the benzene induces the asphaltenes aggregation followed by their precipitation and compaction. Fast asphaltene aggregation process under heptane flow leads to the formation of the deposit firmly fixed to the surface, while the precipitates formed during the diffusion process of heptane into the benzene can be easily taken from the channel. The FTIR spectroscopic imaging of the deposits formed revealed the spatial inhomogeneity of the precipitated asphaltenes in the direction of the heptane flow in microfluidic channel which is reflected in their different chemical composition and the presence of different functional groups (CH2–CH3, CO, SO). In particular, it was found that asphaltenes of different types and different CH2/CH3 ratios gradually start to precipitate in the direction of n-heptane flow. The data obtained demonstrate the importance of local concentration of flocculants as well as local characteristics of the system for asphaltenes aggregation, and overall precipitation process in flow regime.

Three New Niccolites: High-Temperature Phase Transitions, Prominent Anisotropic Thermal Expansions, Dielectric Anomalies, and Magnetism.

Three new iso-structural ammonium metal formates of [dmpnH2 ][M2 (HCOO)6 ], in which dmpnH2 2+ =N,N'-dimethyl-1,3-propylenediammoium and M=divalent Co, Zn and Mg ions, are reported. They possess niccolite metal formate frameworks with long-shaped cavities for the accommodation of dmpnH2 2+ cations. The three materials display reversible phase transitions of similar mechanism from ordered, antipolar or antiferroelectric, low-temperature phases in space group C2/c, to disordered, paraelectric, high-temperature phases in space group P 1c, with quite high critical temperatures of 366, 370, and 334 K for Co, Zn, and Mg members, respectively. On warming, the dmpnH2 2+ cation experiences an ordered state with gradual increase of the local vibration motions of the central CH2 and terminal CH3 groups, a partially disordered state with gradually enhanced flipping motion between the major and minor orientations, and finally a twisting or rotating motion after the phase transition, accompanied by prominent anisotropic thermal expansions and dielectric anomalies/relaxations. The phase transition characters and relevant properties also exhibit a subtle metal-dependence. The Co member shows spin-canted antiferromagnetism below the Néel temperature of 16.1 K, with unusual large spontaneous magnetization and coercive field.

Molecular characterization and expression analysis of secretory immunoglobulin M (IgM) heavy chain gene in rohu, Labeo rohita

Immunoglobulin M (IgM) is the major isotype among teleost immunoglobulins. The present study was aimed to explore IgM heavy chain gene and its expression profile in rohu. Full-length IgM heavy chain cDNA of rohu consisted of 1994 bp encoding a polypeptide of 576 amino acid residues including a leader peptide, variable (VH) and constant (CH1–CH2–CH3–CH4) domains confirming the secretory form of IgM. The sequence carries conserved residues such as cysteine, tryptophan and amino acid motifs like ‘YYCAR’ and ‘FDYWGKGT–VTV–S’. The predicted 3 D model confirmed various domains of rohu IgM heavy chain. Phylogenetic tree analysis revealed that IgM heavy chain gene of rohu shared the same cluster with that of other cyprinid fishes. Tissue distribution analysis showed the predominant level of IgM heavy chain gene expression in kidney, spleen and intestine. IgM heavy chain gene expression in rohu kidney was found to be up-regulated and reached a maximum at 7 days post-challenge with Aeromonas hydrophila. These findings demonstrate the first report of full-length secretory IgM heavy chain gene in rohu. Besides, IgM heavy chain gene was highly expressed in major lymphoid tissues and bacterial challenge influenced its expression which further confirmed its role in the adaptive humoral immune response.

Reaction between Peroxy and Alkoxy Radicals Can Form Stable Adducts.

Peroxy (RO2) and alkoxy (RO) radicals are prototypical intermediates in any hydrocarbon oxidation. In this work, we use computational methods to (1) study the mechanism and kinetics of the RO2 + OH reaction for previously unexplored “R” structures (R = CH(O)CH2 and R = CH3C(O)) and (2) investigate a hitherto unaccounted channel of molecular growth, R′O2 + RO. On the singlet surface, these reactions rapidly form ROOOH and R′OOOR adducts, respectively. The former decomposes to RO + HO2 and R(O)OH + O2 products, while the main decomposition channel for the latter is back to the reactant radicals. Decomposition rates of R′OOOR adducts varied between 103 and 0.015 s–1 at 298 K and 1 atm. The most long-lived R′OOOR adducts likely account for some fraction of the elemental compositions detected in the atmosphere that are commonly assigned to stable covalently bound dimers.

Theoretical study on polyglycerine polynitrates for potential high-energy plasticizers of propellants

Polyglycerine polynitrates such as nitroglycerine can be used as energetic plasticizers of propellants. In this study, 29 derivatives of nitroglycerine are investigated at the B3LYP/6-31G* level of the density functional theory. The corrected theoretical densities ([Formula: see text]) are predicted and are found to be very close to the experimental values. Detonation properties are calculated using the modified Kamlet–Jacobs equations and the specific impulse (Is) is evaluated according to the maximum exothermic principle. A new parameter K, which is the product of Is and [Formula: see text], is proposed to evaluate the overall energetic characteristics of compounds. Thermal stability is discussed by calculating the bond dissociation energies or bond dissociation energy barriers. The O–NO2 bond has the smallest bond dissociation energy and is the trigger bond for each of the studied compounds. The influence of the –ONO2 and –CH2–O–CH2–CH(ONO2)– groups, which is useful for design of new high energy plasticizers, is also discussed. Comprehensively considering the energetic properties and the stability, DGPN, DGHN, TriGHeptaN, TriGON, TriGNN, TetraGNN, TetraGDeN, TetraGUN, and TetraGDoN are possibly better energetic plasticizers of solid propellants than nitroglycerine.

Acyclic nucleoside phosphonates containing the amide bond: hydroxy derivatives

To study the influence of a linker rigidity and changes in donor–acceptor properties, three series of nucleotide analogs containing a P–X–HN–C(O)– residue (X=CH(OH)CH2, CH(OH)CH2CH2, CH2CH(OH)CH2) as a replacement for the P–CH2–O–CHR– fragment in acyclic nucleoside phosphonates, e.g., adefovir, cidofovir, were synthesized. EDC proved to provide good yields of the analogs from the respective ω-amino-1- or -2-hydroxyalkylphosphonates and nucleobase-derived acetic acids. New phosphorus–nucleobase linkers are characterized by two fragments of the restricted rotation within amide bonds and in four-atom units (P–CH(OH)–CH2–N, P–CH(OH)–CH2–C and P–CH2–CH(OH)–C) in which antiperiplanar disposition of P and N/C atoms was deduced from 1H and 13C NMR spectral data. The synthesized analogs P–X–HNC(O)–CH2B [X=CH(OH)CH2, CH(OH)CH2CH2, CH2CH(OH)CH2] appeared inactive in antiviral assays on a wide variety of DNA and RNA viruses at concentrations up to 100 μM, while two phosphonates showed cytostatic activity towards myeloid leukemia (K-562) and multiple myeloma cells (MM.1S) with IC50 of 28.8 and 40.7 μM, respectively.Graphical abstract

Kinetics and Mechanism of Aspartic Acid Adsorption and Its Explosive Decomposition on Cu(100).

The mechanism and kinetics of aspartic acid (Asp, HO2CCH(NH2)CH2CO2H) decomposition on Cu(100) have been studied using X-ray photoemission spectroscopy and temperature-programmed reaction spectroscopy. We investigate the Asp decomposition mechanism in detail using unlabeled d-Asp and isotopically labeled l-Asp-4-13C (HO2CCH(NH2)CH213CO2H), l-Asp- d7 (DO2CCD(ND2)CD2CO2D), l-Asp-2,3,3- d3 (HO2CCD(NH2)CD2CO2H), and l-Asp-15N-2,3,3- d3 (HO2CCD(15NH2)CD2CO2H). The monolayer of Asp adsorbed on the Cu(100) surface is in a doubly deprotonated bi-aspartate form (-O2CCH(NH2)CH2CO2-). During heating, Asp decomposes on Cu(100) with kinetics consistent with a vacancy-mediated explosion mechanism. The mechanistic steps yield CO2 by sequential cleavage of the C3-C4 and C1-C2 bonds, and N≡CCH3 and H2 via decomposition of the remaining CH(NH2)CH2 intermediate. Deuterium labeling has been used to demonstrate that scrambling of H(D) occurs during the decomposition to acetonitrile of the CD(NH2)CD2 intermediate formed by decarboxylation of l-Asp-2,3,3- d3 and l-Asp-15N-2,3,3- d3.

Effects of [Bmim][Cl] ionic liquid with different concentrations on the functional groups and wettability of coal

In view of high dust concentration in coal mining and difficulty of traditional water injection in coal wetting, the effects of [Bmim][Cl] (1-butyl-3-methylimidazole chloride) ionic liquid with different concentrations on wetting performance and functional groups of coals have been studied. Optical droplet morphology analysis system and FTIR (Fourier transform infrared spectrometer) were used. The results showed that coal samples treated with [Bmim][Cl] ionic liquid had a significant change in the content of aliphatic groups. In the coal samples treated with 0% concentration [Bmim][Cl], the content of CH2 groups was 77.86%, CH3 groups was 14.07%. When [Bmim][Cl] concentration was 4%, the content of CH2 groups decreased to 24.55%, CH3 groups increased to 61.25%. Besides, the contact angle is the minimal of a 41.1° at 4% ionic liquid concentration. The relationship between contact angles and contents of functional groups were analyzed. Results showed that the content of CH3 groups and CH2 groups had the greatest effect on the contact angle and 4% [Bmim][Cl] ionic liquid treatment can effectively reduce the contact angle and improve the coal wettability. It is of great significance to increase coal wettability and reduce dust generation by changing the contents of functional groups.

Correction: Sub-Doppler infrared spectroscopy of resonance-stabilized hydrocarbon intermediates: ν3/ν4 CH stretch modes and CH2 internal rotor dynamics of benzyl radical.

Correction for 'Sub-Doppler infrared spectroscopy of resonance-stabilized hydrocarbon intermediates: ν3/ν4 CH stretch modes and CH2 internal rotor dynamics of benzyl radical' by A. Kortyna et al., Phys. Chem. Chem. Phys., 2017, 19, 29812-29821.

Influence of n-Butanol Addition on C3H3 Formation in n-Butane Combustion

The effects of different n-butanol blending ratios (Rb) on the formation of propargyl radical (C3H3), an important benzene precursor, during the combustion of n-butanol/n-butane blends are studied. A detailed kinetic combustion model of n-butanol/n-butane is developed and the premixed n-butanol/n-butane flames are calculated at an equivalence ratio of 1.5, an initial pressure of 1.0 atm, and a temperature range from 800 to 2000 K in a perfectly stirred reactor (PSR), with Rb varying from 0 to 1.0. The results show that under the investigated conditions, the peak value of the mole fraction of C3H3 decreases non-linearly with the increase of Rb. Due to the interaction between combustion products of n-butane and n-butanol during the combustion process, the actual peak mole fraction of C3H3 is higher than the theoretical value. A rate of production (ROP) analysis reveals that the number of β-carbon atoms in the molecule of n-butane and n-butanol affects the efficiency of H-abstraction reactions in generating 2-butyl (sC4H9) and C4H8OH-3 (CH3–*CH–CH2–CH2–OH), which are the two major original sources of C3H3. For both n-butane and n-butanol, the main pathway of forming C3H3 from propene (C3H6) is basically the same, which is C3H6 → C3H5-a (symmetric allyl radical) → C3H4-a (allene) → C3H4-p (propyne) → C3H3. When Rb ranges from 0.4 to 0.6, the deviation degrees of the peak mole fraction of the involved C3 species reach a maximum, indicating that the interaction between the two fuels is the most significant. The non-linear decrease in the mole fraction of C3H3 can attribute to three reasons: (a) the increase of Rb promotes the increase of the conversion ratios of n-butane to sC4H9 and n-butanol to C4H8OH-3; (b) the contribution ratios of the reactions involved in the C3H5-a → C3H4-a → C3H4-p → C3H3 pathway decrease with increasing Rb; (c) C3H5-t (tertiary allyl radical) → C3H4-p → C3H3 is the secondary pathway for the formation of C3H3. With the increase of Rb, the dependence of C3H4-p on C3H5-t increases and the conversion ratio of C3H5-t to C3H4-p increases. This study investigates the non-linear decrease of the mole fraction of C3H3 by revealing the interactions between n-butanol and n-butane during the combustion, which can help better understand the effect of n-butanol on the formation of benzene.

Surrogate Fuels Formulation for FACE Gasoline Using the Nuclear Magnetic Resonance Spectroscopy

An efficient surrogate fuel formulation methodology, which directly uses the chemical structure information from nuclear magnetic resonance (NMR) spectroscopy analysis, has been proposed. Five functional groups, paraffinic CH2, paraffinic CH3, aromatic C-CH, olefinic CH-CH2, and cycloparaffin CH2, have been selected to show the basic molecular structure of the fuels for the advanced combustion engines (FACE) fuels. A palette that contains six candidate components, n-heptane, iso-octane, toluene, 2,5-dimethylhexane, methylcyclohexane, and 1-hexene, is chosen for different FACE fuels, based on the consideration that surrogate mixtures should provide the representative functional groups and comparable molecular sizes. The kinetic mechanisms of these six candidate components are chosen to assemble a detailed mechanism of each surrogate fuel for FACE gasoline. Whereafter, the accuracy of FACE A and F surrogate models was demonstrated by comparing the model predictions against experimental data in homogeneous ignition, jet stirred reactor oxidation, and premixed flame.

Selective Nitrogen-Atom Transfer Driven by a Highly Efficient Intersystem Crossing in the [CeON]+ /CH4 System.

The thermal gas-phase reactions of [CeON]+ with methane have been explored by FT-ICR mass spectrometry and high-level quantum-chemical calculations. Nitrogen-atom transfer from the cluster ion to methane was observed as the only reaction channel. Based on computational work, the neutral molecule formed corresponds to either CH2 NH2 or CH3 NH. In addition to a rather weak OCe+ -N bond, this reaction benefits from a highly efficient intersystem crossing. Mechanistic aspects and the associated electronic origins are discussed, and a detailed comparison of [CeON]+ , [CeO]+ , [CeN]+ , [CeO2 ]+ , and atomic N in their reactions with CH4 is given.

Reactivity of Selenocystine and Tellurocystine: Structure and Antioxidant Activity of the Derivatives.

l-Selenocystine (5) and l-tellurocystine (6) have been prepared and the reactivity of these amino acids, i.e., oxidation of 5 and 6, has been performed at various pH values. Hydrogen peroxide was used as an oxidant and it was treated with 5 and 6 in excess in acidic and basic media. Compound 5, upon oxidation, afforded SeIV and SeVI products. Selenocysteic acid [HO3 SeCH2 CH(NH2 )COOH] 9, a novel SeVI compound, was isolated and characterised by single-crystal X-ray diffraction studies. In contrast, l-tellurocystine, upon oxidation with H2 O2 , afforded TeII and TeIV products. Zwitterionic organotellurolate(IV), [TeCl3 CH2 CH(NH3 )COOH] 13, was isolated and characterised by NMR and IR spectroscopy, mass spectrometry and elemental analysis. Compound 13 crystallizes in an orthorhombic space group. l-Tellurocystine, when reduced with NaBH4 , produced the desired tellurolate intermediate, which was trapped with bromoacetic acid. Furthermore, l- and d-tellurocysteine derivatives, [(RTeCH2 CH(NH2 )COOH) R=phenyl, substituted phenyl and naphthyl (24-39)] were synthesised and evaluated for their glutathione peroxidase (GPx)-like activities. The results show that l-tellurocysteine derivatives have higher activity than their D-tellurocysteine analogues. DFT calculations for l-tellurocysteine derivatives provided information about the bond lengths and bond angles. This study reveals that the introduction of naphthyl substituents (35-38) leads to twisted conformation of the amino acid derivatives.

Broadband UV-assisted thermal annealing of low-k silicon carbonitride films using a C-rich silazane precursor

Low-k dielectric silicon carbonitride (SiCxNy) films are deposited by plasma-enhanced chemical vapor deposition using a carbon-rich silazane precursor, N-methyl-aza-2,2,4-trimethylsilacyclopentane (SiC7NH17), at 100 °C. The post-treatments of SiCxNy films are carried out by thermal annealing and a broadband UV-assisted thermal annealing (UV-annealing) at 400 °C for 5 min. Compared to the thermal annealing treatment, UV-annealing can improve both dielectric and mechanical properties of low-k SiCxNy films. Under thermal annealing, SiCxNy films show great thermal stability, but little structural change. In contrast, upon UV-annealing, most of the Si–H and N–H bonds are broken up, which induces more Si–N cross-linking and converts Si–C matrix into Si–N matrix. The ethylene bridges in Si–(CH2)2–Si also remain intact, but the unbridged hydrocarbons in Si–(CH2)2–N and Si–CH2–CH3 bonds decompose completely during the UV-annealing process. These account for the reduced dielectric constant to k = 3.2 from 3.6 and a 21% enhancement of Young's modulus to 7.4 GPa in the SiCxNy films after UV-annealing. Broadband UV-annealing shows promise as a post-treatment method for enhancing the properties of low-k dielectric barrier, SiCxNy films.

Highly Fluorescent and Stable Black Phosphorus Quantum Dots in Water.

Although 2D black phosphorus (BP) shows excellent optical and electronic properties, there are few reports on the photoluminescence (PL) properties of BP nanostructures because of the low yield of mechanical exfoliation, instability in water, and relatively weak emission. Herein, liquid exfoliation is combined with surface passivation to produce fluorescent BP quantum dots (BPQDs) with a high yield. The BPQDs exhibit strong PL in both ethanol and water and the absolute fluorescent quantum yield in water reaches 70%. Moreover, the BPQD solution exhibits stable PL for 150 d under ambient conditions and better photostability than conventional organic dyes and heavy-metal semiconducting nanostructures with intense fluorescence. The experiments and theoretical calculation reveal that the intense and stable PL originates from the intrinsic band-to-band excitation states and two surface states related to the POH and POCH2 CH3 bonding structures introduced by passivation. The polar water molecules remove many nonradiative centers and simultaneously increase the P-related fluorescent groups on the surface of BPQDs. Therefore, PL from the BPQDs in water is enhanced largely. The excellent fluorescent properties of BPQDs in an aqueous solution bode well for bioimaging and the negligible biotoxicity and distinct cell images suggest large potential in the biomedical and display fields.

Dual role of methyl-β-cyclodextrin in the emulsion polymerization of highly hydrophobic plant oil-based monomers with various unsaturations

Although series of latexes from plant oil-based acrylic monomers (POBMs) were recently synthesized in emulsion, two factors—allylic termination (the chain transfer reaction to the fatty acid double bonds) and the poor aqueous solubility of POBMs—lead to the lower total monomer conversion and molecular weight of the resulting latex polymers.In this study, amphiphilic oligosaccharide, methyl-β-cyclodextrin (M-β-CD), was used to improve the polymerizability of monomers from high oleic soybean (HO-SBM) and linseed (LSM) oil in copolymerization with styrene. Using X-ray diffractometry and differential scanning calorimetry, interactions between the monomers and M-β-CD were confirmed, while the formation of 1:1 complex from oligosaccharide and each monomer molecules was demonstrated by mass spectrometry.In the presence of “host-guest” complexes, polymer yield increases as the coagulum amount drops during the emulsion polymerization of both plant oil-based monomers with styrene indicating their enhanced aqueous solubility. Remarkably, latex polymers with a consistently higher molecular weight were obtained in the presence of M-β-CD. The complex formation and incorporation of monomer molecules into the oligosaccharide cavities protect the fatty acid moieties and diminishes chain transfer. The latter assumption was quantitatively confirmed in 1H NMR spectroscopy by determining the number of protons of the alkyl carbon−carbon double bonds (–CH = CH–) and the bisallylic hydrogen atoms (–CH = CH–CH2–CH = CH–) in the unsaturated fatty acid moieties of the latex copolymers. The observed effect is more pronounced for more unsaturated monomer from linseed oil.Based on the obtained results, M-β-CD plays a dual role in both enhancing POBM polymerizability as well as protecting against allylic termination chain transfer.