Odd Number Of Carbon Atoms Research Articles

Influence of the odd‐even effect of dicarboxylic acids as crosslinker on the physicochemical properties of polyvinyl alcohol

AbstractPolyvinyl alcohol (PVA) was crosslinked with a homologous series of four different dicarboxylic acids, HOOC(CH2) n‐2COOH (n = 2 to 5) viz. oxalic acid (OA; C2), malonic acid (MA; C3), succinic acid (SA; C4) and glutaric acid (GA; C5) containing odd and even number of carbon atoms. The characterization and assessment of synthesized crosslinked films were done using ATR‐FTIR, XRD, SEM, AFM, DSC, rheology, percent swelling and sessile drop contact angle. The odd‐even effect of dicarboxylic acids was observed to significantly influence the physicochemical properties of PVA when employed as a crosslinker. PVA films crosslinked using dicarboxylic acids containing an even number of carbon atoms, displayed translucency, roughness, and an irregular matrix. In contrast, films incorporating an odd number of carbon atoms were transparent, homogenous, and densely packed. Furthermore, films containing even acids exhibited relatively lower crystallinity, lower melting temperature (Tm) and displayed an unexpected irregular trend in swelling as crosslinker concentration increased compared to films containing dicarboxylic acids with an odd number of carbon atoms which exhibits a consistent swelling with increasing crosslinker concentration. These results are attributed to the difference in the solubility and crystal structures of the odd‐even series of dicarboxylic acids.

Solid–Liquid Phase Equilibrium of the n-Nonane + n-Undecane System for Low-Temperature Thermal Energy Storage

The current article presents an exploration of the solid–liquid phase diagram for a binary system comprising n-alkanes with an odd number of carbon atoms, specifically n-nonane (n-C9) and n-undecane (n-C11). This binary system exhibits promising characteristics for application as a phase change material (PCM) in low-temperature thermal energy storage (TES), due to the fusion temperatures of the individual components, thereby motivating an in-depth investigation of the solid–liquid phase diagram of their mixtures. The n-nonane (n-C9) + n-undecane (n-C11) solid–liquid phase equilibrium study herein reported includes the construction of the phase diagram using Differential Scanning Calorimetry (DSC) data, complemented with Hot–Stage Microscopy (HSM) and low-temperature Raman Spectroscopy results. From the DSC analysis, both the temperature and the enthalpy of solid–solid and solid–liquid transitions were obtained. The binary system n-C9 + n-C11 has evidenced a congruent melting solid solution at low temperatures. In particular, the blend with a molar composition xundecane = 0.10 shows to be a congruent melting solid solution with a melting point at 215.84 K and an enthalpy of fusion of 13.6 kJ·mol–1. For this reason, this system has confirmed the initial signs to be a candidate with good potential to be applied as a PCM in low-temperature TES applications. This work aims not only to contribute to gather information on the solid–liquid phase equilibrium on the system n-C9 + n-C11, which presently are not available in the literature, but especially to obtain essential and practical information on the possibility to use this system as PCM at low temperatures. The solid–liquid phase diagram of the system n-C9 + n-C11 is being published for the first time, as far as the authors are aware.

Odd-Even Alkyl Chain Effects on the Structure and Charge Carrier Transport of Two-Dimensional Sn-Based Perovskite Semiconductors.

Oscillations in the chemical or physical properties of materials, composed of an odd or even number of connected repeating methylene units, are a well-known phenomenon in organic chemistry and materials science. So far, such behavior has not been reported for the important class of materials, perovskite semiconductors. This work reports a distinct odd-even oscillation of the molecular structure and charge carrier transport properties of phenylalkylammonium two-dimensional (2D) Sn-based perovskites in which the alkyl chains in the phenylalkylammonium cations contain varying odd and even carbon numbers. Density functional theory calculations and grazing-incidence wide-angle X-ray scattering characterization reveal that perovskites with organic ligands containing an alkyl chain with an odd number of carbon atoms display a disordered crystal lattice and tilted inorganic octahedra accompanied by reduced mobilities. In contrast, perovskites with cations of an even number of carbon atoms in the alkyl chain form more ordered crystal structures, resulting in improved charge carrier mobilities. Our findings disclose the importance of minor changes in the molecular conformation of organic cations have an effect on morphology, photophysical properties, and charge carrier transport of 2D layered perovskites, showcasing alkyl chain engineering of organic cations to control key properties, of layered perovskite semiconductors.

Sphingolipid profiling reveals differential functions of sphingolipid biosynthesis isozymes of Caenorhabditis elegans

Multiple isozymes are encoded in the Caenorhabditis elegans genome for the various sphingolipid biosynthesis reactions, but the contributions of individual isozymes are characterized only in part. We developed a simple but effective reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) method that enables simultaneous identification and quantification of ceramides (Cer), glucosylceramides (GlcCer), and sphingomyelins (SM) from the same MS run. Validating this sphingolipid profiling method, we show that nearly all 47 quantifiable sphingolipid species found in young adult worms were reduced upon RNA interference (RNAi) of sptl-1 or elo-5, which are both required for synthesis of the id17:1 sphingoid base. We also confirm that HYL-1 and HYL-2, but not LAGR-1, constitute the major ceramide synthase activity with different preference for fatty acid substrates, and that CGT-3, but not CGT-1 and CGT-2, plays a major role in producing GlcCers. Deletion of sms-5 hardly affected SM levels. RNAi of sms-1, sms-2, and sms-3 all lowered the abundance of certain SMs with an odd-numbered N-acyl chains (mostly C21 and C23, with or without hydroxylation). Unexpectedly, sms-2 RNAi and sms-3 RNAi elevated a subset of SM species containing even-numbered N-acyls. This suggests that sphingolipids containing even-numbered N-acyls could be regulated separately, sometimes in opposite directions, from those containing odd-numbered N-acyls, which are presumably monomethyl branched chain fatty acyls. We also find that ceramide levels are kept in balance with those of GlcCers and SMs. These findings underscore the effectiveness of this RPLC-MS/MS method in studies of C. elegans sphingolipid biology.

Indium-Mediated Acyloxyallylation-Based Synthesis of Galacto-Configured Higher-Carbon Sugar Alcohols as Potential Phase Change Materials.

Sugar alcohols fulfilling specific structural requirements are a substance class with great potential as organic phase change materials (PCMs). Within this work, we demonstrate the indium-mediated acyloxyallylation (IMA) as a useful strategy for the synthesis of higher-carbon sugar alcohols of the galacto-family featuring all hydroxyl groups in a 1,3-anti-relationship with three major synthetic achievements: first, the dihydroxylation of the IMA-derived allylic sugar derivates was systematically studied in terms of diastereoselectivity, revealing a high degree of substrate control toward anti-addition. Second, we demonstrated the use of a "double Mitsunobu" reaction, inverting the stereochemistry of terminal diols. Third, the IMA toolbox was expanded to accomplish the synthesis of derivatives with up to 10 carbon atoms from particularly unreactive aldoses. Thermal investigations of all synthesized sugar alcohols, including examples with exclusive 1,3-anti- and suboptimal 1,3-syn-relationships as well as even and odd numbers of carbon atoms, were performed. We observed clear trends in melting points and thermal storage densities and discovered limitations of organic substances in this class with melting points above 240 °C as PCMs in terms of thermal stability. With our study, we provide insights into the dependence of thermal properties on structural features, thus contributing to further understanding of organic PCMs for thermal energy storage applications.

IR spectroscopic characterization of products of methane and cyclopropane activation by Ru cations

Methane and cyclopropane (c-C3H6) were reacted with Ru+ ions in a room temperature ion trap and the resulting products were identified using a combination of mass spectrometry, IR action spectroscopy, and density functional theory calculations. In the reaction with methane, no products with odd numbers of carbon atoms were located, whereas significant amounts of products with even numbers of carbon atoms were observed. We identified [Ru,2C,4H]+ as the Ru+ ion with an ethene ligand attached, and [Ru,4C,6H]+ as a Ru(η4-cis-1,3-butadiene)+ complex. The barrier toward formation of Ru(C2H4)+ + 2H2 was calculated at the B3LYP/def2-TZVPPD level to be 0.80 eV above the energy of the ground state Ru+ (4F) + 2 CH4 reactants. In the reaction of c-C3H6 with Ru+, we identified the dehydrogenation product [Ru,3C,4H]+ as Ru(η2-propyne)+, [Ru,2C,2H]+ as Ru+ with an ethyne ligand, and [Ru,5C,5H]+ as Ru(η5-c-C5H5)+ having a cyclopentadienyl ligand.

Can even-membered liquid crystal dimers exhibit the twist-bend nematic phase? The preparation and properties of disulphide and thioether linked dimers

ABSTRACTCyanobiphenyl-based liquid crystal dimers containing a disulfide link in the spacer, the 4-[4-[2-[2-[4-(4-cyanophenyl)phenyl]alkyldisulfanyl]alkyl]-phenyl]benzonitriles (CBnSSnCB), are reported. The alkyl fragment is varied from two to nine carbon atoms, and all eight homologues exhibit nematic behaviour. In addition, the dimer containing heptamethylene fragments (CB7SS7CB) exhibits a twist-bend nematic phase despite having an even-membered spacer. The values of the nematic–isotropic transition temperature, TNI, are higher for dimers containing an odd number of carbon atoms in each alkyl fragment. This surprising behaviour is interpreted in terms of the C-S-S-C torsion angle being around 88° that ensures that the molecular shape is bent irrespective of the parity of the alkyl fragments. For odd-membered fragments, however, the average shape is less bent and higher values of TNI are observed. The more uniform molecular curvature of CB7SS7CB accounts for the observation of the NTB phase. We also report the behaviour of two members of the 4-[4-[3-[2-[4-(4-cyanophenyl)phenyl]alkyldisulfanyl]-alkyl]phenyl]benzonitriles (CBnSmCB) which contain a thioether link embedded in the spacer. Both dimers exhibited nematic behaviour. The thioether link reduces the value of TNI compared to that of the dimer with an alkyl spacer. A much larger decrease in the nematic-twist-bend nematic temperature is observed and is attributed to a change in shape.

Comparative Study of the Yield and Chemical Profile of Rose Oils and Hydrosols Obtained by Industrial Plantations of Oil-Bearing Roses in Bulgaria

Bulgaria is famous for its oil-bearing rose. R. damascena Mill. and R. alba L. are mainly cultivated in the country, but a recent survey of industrial plantations in 2020 revealed that R. centifolia L. and hybrids of R. damascena Mill. X R. gallica L. are also common in the rose valley. Although their essential oil cannot be compared in quality with the classic, these species are preferred by farmers with high yields of flowers and resistance to diseases and pests. All these roses are also used to produce rose water and extracts. The aim of this investigation was to compare the yield and chromatographic fingerprints of seven rose oils and hydrosols produced in Bulgaria. The quantitative composition of the main components of the oils was compared with the norms of the world standards. Our study showed that the yield of essential oil from these roses was in the range of 0.015–0.048%. The main group in the chemical composition is terpene alcohols, which vary in range: geraniol (15.85–34.02%), citronellol (6.70–28.72%), and nerol (5.80–11.90%) but with a different ratio. Hydrocarbons are represented by saturated aliphatic homologs with an odd number of carbon atoms, the main ones being nonadecane (8.10–22.67%), heneicosane (4.37–10.21%), heptadecane (1.07–2.98%), and triclosan (0.81–5.90%). In contrast, the chemical profile of the hydrosols was performed using phenylethyl alcohol (27.45–69.88%), geraniol (13.72–28.67%), and citronelol+nerol (4.56–17.37%). The results show that the presence of plantations with a genotype different from that of R. damascena implies differences in the quality of rose oils and hydrosols. This determines their properties of use.

The debut and course of the neonatal form of propionic aciduria: a clinical case

Propionic aciduria (PA) is an autosomal recessive hereditary disease from the group of organic aciduria, caused by a deficiency of propionyl-CoA carboxylase, leading to impaired metabolism of methionine, threonine, valine, isoleucine, and fatty acids with an odd number of carbon atoms and cholesterol. The neonatal form of PA manifests itself during the first week of life, is characterized by an acute onset and a crisis course, which is accompanied by severe metabolic acidosis, hypoglycemia, hyperketonemia, hyperammonemia. Clinical symptoms are dominated by neurological disorders up to stupor or coma, which can lead to death. Since 2023, expanded neonatal screening has been introduced throughout the Russian Federation, which includes 36 groups of nosologies, as well as a number of hereditary metabolic diseases.
 Despite the inclusion of this pathology in expanded neonatal screening, doctors’ awareness of clinical manifestations and necessary therapy remains insufficient. Often such patients are diagnosed with, for example: hypoxic-ischemic damage to the central nervous system, acute meningoencephalitis, and others, which leads to inadequate therapy with the development of fatal neurological consequences.
 Therefore, the totality of knowledge and alertness of doctors regarding diseases from the group of hereditary metabolic diseases will help not only to suspect this pathology in a timely manner, but also to prescribe adequate therapy in time, which in the future will make it possible to prevent serious consequences and neurological disorders, as well as disability of patients.

Synthesis, Solution, and Solid State Properties of Homological Dialkylated Naphthalene Diimides-A Systematic Review of Molecules for Next-Generation Organic Electronics.

This systematic study aimed at finding a correlation between molecular structure, solubility, self-assembly, and electronic properties of a homological series of N-alkylated naphthalene diimides (NDIs). NDIs are known for their n-type carrier mobility and, therefore, have potential in the field of organic electronics, photovoltaics, and sensors. For the purpose of this study, nine symmetrical N,N'-dialkylated naphthalene diimides (NDIC3-NDIC11) were synthesized in the reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride with alkylamines ranging from propyl- to undecyl-. The NDIs were characterized by spectroscopic (NMR, UV-Vis, FTIR), microscopic, and thermal methods (TGA and DSC), and X-ray diffraction (XRD). Our experimental study, extensively referring to findings reported in the literature, indicated that the NDIs revealed specific trends in spectroscopic and thermal properties as well as solubility and crystal morphology. The solubility in good solvents (chloroform, toluene, dichlorobenzene) was found to be the highest for the NDIs substituted with the medium-length alkyl chains (NDIC5-NDIC8). Systematic FTIR and XRD studies unraveled a distinct parity effect related to the packing of NDI molecules with odd or even numbers of methylene groups in the alkyl substituents. The NDIs with an even number of methylene groups in the alkyl substituents revealed low-symmetry (P1-) triclinic packing, whereas those with an odd number of carbon atoms were generally monoclinic with P21/c symmetry. The odd-even parity effect also manifested itself in the overlapping of the NDIs' aromatic cores and, hence, the π-π stacking distance (dπ-π). The odd-numbered NDIs generally revealed slightly smaller dπ-π values then the even-numbered ones. Testing the NDIs using standardized field-effect transistors and unified procedures revealed that the n-type mobility in NDIC6, NDIC7, and NDIC8 was 10- to 30-fold higher than for the NDIs with shorter or longer alkyl substituents. Our experimental results indicate that N,N'-alkylated NDIs reveal an optimum range of alkyl chain length in terms of solution processability and charge transport properties.

Occurrence, fate and risk assessment of per- and polyfluoroalkyl substances in wastewater treatment plants in Shaanxi, China

Wastewater treatment plants (WWTPs) are considered as major sinks for per- and polyfluoroalkyl substances (PFASs). However, conventional WWTPs with low efficiency are also a secondary point source of PFASs entering the environment. Herein, a large-scale investigation of PFASs was conducted in 44 WWTPs throughout Shaanxi Province in the transitional zone between North and South China. The composition profiles of target PFASs differed between wastewater and sludge samples. Perfluorobutanoic acid was dominant in wastewater influent and effluent samples, with maximum concentrations of 59.8 and 11.4 ng/L, respectively. Perfluorooctane sulfonic acid occurred predominantly in sludge samples, with a maximum concentration of 73.2 ng/g. Through wastewater treatment, short-chain PFASs with an even number of carbon atoms were mostly removed, whereas short-chain PFASs with an odd number of carbon atoms were primarily discharged into receiving water. Long-chain PFASs (perfluoroalkyl carboxylic acids: C ≥ 8; perfluoroalkane sulfonic acids: C ≥ 6) were not removed efficiently and secondary production might occur during treatment. Based on the risk quotient, PFASs residues in wastewater effluent posed minimal ecological risk, but the residues in sludge posed low to high potential risk. The mass loadings of PFASs discharged through wastewater and sludge were 15.5 and 3.74 kg/year, respectively, from all WWTPs in Shaanxi Province.

Informativity of Locally Estimated Odd-Numbered Higher Fatty Acids for Differential Diagnosis of HSIL and Cervical Cancer

Background. Current issues in the cytological assessment of cervical epithelium can hamper differential diagnosis of high-grade squamous intraepithelial lesion (HSIL) and cervical cancer.Aim. To determine the informativity of locally estimated values of odd-numbered higher fatty acids as differential markers in HSIL and cervical cancer.Materials and methods. Previous original data on the higher fatty acids content in cervical biopsy of primary pre-treatment HSIL and cervical cancer patients were analysed retrospectively. The study cohorts: clinical cohort I — 30 HSIL patients; clinical cohort II — 45 primary stage I squamous cervical cancer patients. Statistical methods included the analyses of ROC curves, sensitivity (Se), specificity (Sp) and accuracy (Ac).Results. Among all odd-numbered higher fatty acids, the following molecular markers (local thresholds) are differential for cervical cancer: C15:0 ≤1.91 %/cell (Se = 0.81; Sp = 0.84; Ac = 0.83; AUC = 0.81); C15:1 ≤1.72 %/cell (Se = 0.96; Sp = 0.91; Ac = 0.92; AUC = 0.96); C17:0 ≤2.95 %/cell (Se = 0.94; Sp = 0.93; Ac = 0.97; AUC = 0.97); C17:1 ≤1.11 %/cell (Se = 0.96; Sp = 0.98; Ac = 0.96; AUC = 1.0); C19:0 ≤1.17 %/cell (Se = 1.0; Sp = 1.0; Ac = 1.0; AUC = 1.0).Discussion. Tumour cells are known to possess atypical metabolism, which produces large amounts of higher fatty acids with odd numbers of carbon atoms. The study focused on the value of locally estimated odd-numbered higher fatty acids as differential molecular markers in HSIL and cervical cancer.Conclusion. The results suggest that C19:0 estimates are applicable in diagnosis of HSIL and cervical cancer.

Odd-Number Cyclo[n]Carbons Sustaining Alternating Aromaticity.

Cyclo[n]carbons (n = 5, 7, 9, ..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCF-optimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the odd-number cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

On the Question of the Relationship between the Rotational Motion of Molecules and the Alternation of Properties in Homological Series

In the paper the emphasis is placed on attempt to describe the effect of alternation of melting points in homologous series using the example of melting points of alkanes of normal structure from the frame of reference of the concept of rotational motion of molecules in a liquid. In the existing literature, the presence of separate sequences for the melting points of even and odd homologues is usually explained by packing effects, in which, due to different symmetry, even and odd representatives crystallize with different densities of the crystal lattice. However, this behavior can also be explained by the difference in the entropies of the rotational motion of molecules in the liquid phase, which is observed due to the different positions of the axis of rotation for even and odd homologues. The theoretically predicted difference in the moments of inertia for molecules with an even and an odd number of carbon atoms in the chain was confirmed by calculating the moments of inertia of n-alkane molecules, for which the atomic coordinates were optimized using density functional theory calculations

Catalytic oligomerization and polymerization of ethylene with complexes of iron triad metals: influence of metal nature and new prospects

In the last five years the field of catalytic oligomerization and polymerization of olefins using complexes of late transition metals has been the most intensively developing area of post-metallocene catalysis. This review is devoted to detailed analysis of the influence of metal nature on the catalytic properties of systems based on complexes of iron triad metals. Some novel and developing areas of application of such complexes in olefin oligomerization and polymerization (ethylene trimerization, production of olefins with an odd number of carbon atoms and polyethylene waxes, targeted synthesis of heavy fractions of ethylene oligomers) are surveyed. Different approaches to the heterogenization of catalysts on various solid supports are considered.The bibliography includes 225 references.

Structural Odd–Even Effect Impacting the Dimensionality of Transport in BTBT‐CnOH Organic Field Effect Transistors

AbstractThe synthesis and characterization of a series of [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) molecules disubstituted by hydroxy aliphatic chains in positions 2 and 7 (BTBT‐CnOH), where the intralayer molecular stacking alternates between a classical and an inverted herringbone mode as a function of whether the alkyl sides chains have an even or an odd number of carbon atoms are reported. This odd–even effect does not only affect the interlayer distance of the lamellar structures and the melting points, but also the electronic properties. The BTBT‐CnOH odd series develops a classical herringbone pattern with edge‐to‐edge S⋯S interaction chains linked together by face‐to‐edge S⋯S interaction chains with 2D mobility. However, the even series has only edge‐to‐edge interactions in an inverted herringbone organization and thus only a 1D conducting character. These two types of herringbone patterns have different field effect transistor characteristics and mobilities, those of the odd members being systematically higher than their even neighbors. This is the first example of an odd–even effect impacting the electronic properties of an organic semiconductor.

Fatty acids of microalgae: diversity and applications

The possibility of obtaining commercially valuable products from microalgae stimulates scientific research in this direction. The ability of microalgae to accumulate lipids is very promising from the point of view of practical application. The diversity of the composition of microalgae lipids makes it possible to study a wide range of their applications: biofuel production, food products, feed for farm animals and birds, for aquaculture, food additives, etc. Fatty acids (FAs) are involved in the metabolic pathways of formation and conversion of most lipid classes, and their composition largely determines their properties and practical use. As a result, much attention is paid to the study of the composition of fatty acids in microalgae (including cyanobacteria). This review summarizes information on the diversity of the fatty acid composition of microalgae and cyanobacteria, taking into account their rare and unusual categories. The total variety of FA profile of microalgae from different habitats is formed by 135 FAs. Taking into account the length of the hydrocarbon chain, its structure and the presence of substituents, they are distributed into several groups: with an even number of carbon atoms in the chain—81 (short-chain FAs—2, medium-chain FAs—14, long-chain FAs—28, very-long-chain FAs—37), with an odd number of carbon atoms—33, with a branched hydrocarbon chain and additional functional groups—21. Among FAs of microalgae there are both saturated and unsaturated FAs with different numbers of double bonds: saturated FAs—19, monounsaturated FAs—26, polyunsaturated FAs—68. The FA profile of microalgae is rich in omega-3 and omega-6 fatty acids. The review also considers the use of fatty acids as an industrial resource, as well as a biomarker.

Differences in phosphatidylcholine profiles and identification of characteristic phosphatidylcholine molecules in meat animal species and meat cut locations

Phosphatidylcholine (PC) is an essential component of the plasma membrane. Its profile varies with species and tissues. However, the PC profiles in meat have not been explored in depth. This study aimed to investigate the differences in PC profiles between various meat animal species and meat cut sites, along with the identification of characteristic PC molecules. The results demonstrated that the PC profiles of chicken meat differed from those of other species. Significant differences were also observed between the PC profiles of pork meat and the meat obtained from other species. The amount of PCs containing ether bonds was high in pork meat. PCs containing an odd number of carbon atoms were characteristic of beef and lamb meats. Furthermore, PC profiles differed based on the muscle location in chicken and pork. These results suggest that the PC profiles of skeletal muscles are indicators of animal species and muscle location.

An unprecedented π-electronic circuit involving an odd number of carbon atoms in a grossly warped non-planar nanographene.

The formation of π-aromatic circuits along a grossly warped nanographene, C80H30, containing five- and seven-membered rings inserted into a six-membered mesh, reveals global π-circuits at the edge of the backbone. Based on DFT calculations, one of the two most favorable circuits for π-electron delocalization formally has 50 π-electrons abiding by Hückel's rule, whereas the second one formally has 75 π-electrons and, remarkably, it does not follow any of the known rules of aromaticity.

Novel esterquat-based herbicidal ionic liquids incorporating MCPA and MCPP for simultaneous stimulation of maize growth and fighting cornflower

Modern agricultural practices are often based on the use of mixtures of specific herbicides to achieve efficient crop protection. The major drawbacks of commercial herbicidal formulations include the necessity to incorporate toxic surfactants and high volatility of active substances. Transformation of herbicides into herbicidal ionic liquids (HILs) seems to be a promising alternative which allows to almost completely reduce volatility due to ionic interactions. In the scope of this research, we transformed (2-methyl-4-chlorophenoxy)acetic acid (MCPA) into a quaternary ester (esterquat) with the use of derivatives of 2-dimethylaminoethanol. The obtained esterquats were later coupled with (±)−2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) in the form of an anion. The combination of MCPA and MCPA is commonly applied in the UK, EU countries and also in the USA to increase the spectrum of targeted weed species. In the framework of this study, novel HILs with an esterquat moiety incorporating a long alkyl chain (C8, C9, C10, C11, C12, C14) were prepared and characterized in terms of basic physicochemical properties (solubility and volatility) as well as biodegradability. Their phytotoxicity was assessed towards cornflower (Centaurea cyanus) as a model weed and maize (Zea mays) as a crop plant. The presence of the esterquat cation contributed to satisfactory solubility in water and other low polar solvents, which eliminates the need to add exogenous adjuvants. Further experiments indicated that the tested HILs stimulated the germination stage of maize and maintained high herbicidal activity towards cornflower. No significant differences in terms of properties were observed in case of HILs which included alkyl substituents with an odd number of carbon atoms. Future studies should be focused on structural modifications in order to improve the biodegradability as well as field studies for evaluation of commercial applications.