Long-chain Derivatives Research Articles

Rational modification of Neisseria meningitidis β1,3-N-acetylglucosaminyltransferase for lacto-N-neotetraose synthesis with reduced long-chain derivatives

Lacto-N-neotetraose (LNnT), as a neutral core structure within human milk oligosaccharides (HMOs), has garnered widespread attention due to its exceptional physiological functions. In the process of LNnT synthesis using cellular factory approaches, substrate promiscuity of glycosyltransferases leads to the production of longer oligosaccharide derivatives. Here, rational modification of β1,3-N-acetylglucosaminyltransferase from Neisseria meningitidis (LgtA) effectively decreased the concentration of long-chain LNnT derivatives. Specifically, the optimal β1,4-galactosyltransferase (β1,4-GalT) was selected from seven known candidates, enabling the efficient synthesis of LNnT in Escherichia coli BL21(DE3). Furthermore, the influence of lactose concentration on the distribution patterns of LNnT and its longer derivatives was investigated. The modification of LgtA was conducted with computational assistance, involving alanine scanning based on molecular docking to identify the substrate binding pocket and implementing large steric hindrance on crucial amino acids to obstruct LNnT entry. The implementation of saturation mutagenesis at positions 223 and 228 of LgtA yielded advantageous mutant variants that did not affect LNnT synthesis while significantly reducing the production of longer oligosaccharide derivatives. The most effective mutant, N223I, reduced the molar ratio of long derivatives by nearly 70%, showcasing promising prospects for LNnT production with diminished byproducts.

Study of the Structural Chemistry of the Inclusion Complexation of 4-Phenylbutyrate and Related Compounds with Cyclodextrins in Solution: Differences in Inclusion Mode with Cavity Size Dependency.

4-phenylbutyrate (PB) and structurally related compounds hold promise for treating many diseases, including cancers. However, pharmaceutical limitations, such as an unpleasant taste or poor aqueous solubility, impede their evaluation and clinical use. This study explores cyclodextrin (CD) complexation as a strategy to address these limitations. The structural chemistry of the CD complexes of these compounds was analyzed using phase solubility, nuclear magnetic resonance (NMR) spectroscopic techniques, and molecular modeling to inform the choice of CD for such application. The study revealed that PB and its shorter-chain derivative form 1:1 αCD complexes, while the longer-chain derivatives form 1:2 (guest:host) complexes. αCD includes the alkyl chain of the shorter-chain compounds, depositing the phenyl ring around its secondary rim, whereas two αCD molecules sandwich the phenyl ring in a secondary-to-secondary rim orientation for the longer-chain derivatives. βCD includes each compound to form 1:1 complexes, with their alkyl chains bent to varying degrees within the CD cavity. γCD includes two molecules of each compound to form 2:1 complexes, with both parallel and antiparallel orientations plausible. The study found that αCD is more suitable for overcoming the pharmaceutical drawbacks of PB and its shorter-chain derivative, while βCD is better for the longer-chain derivatives.

Profiling of regioisomeric triacylglycerols in pistachio nuts by high-performance liquid chromatography-electrospray ionization mass spectrometry

In this contribution, a non-aqueous reversed-phase liquid chromatographic method coupled to electrospray ionization (ESI) tandem mass spectrometry (LC-MS) is used for the identification of triacylglycerol (TAG) down to the regioisomersíc level in pistachio lipids. Furthermore, for effective profiling of TAG, a two-dimensional (2D) map was employed to identify the entire homologous series of TAGs especially, odd-numbered fatty acid and long-chain derivatives. Notably, TAGs were observed as pairs of regioisomers with distinct retention times and tandem mass spectra. Furthermore, more than 100 TAGs containing 26 fatty acids with 51-63 carbon atoms and 0-3 double bonds were identified in different pistachio samples. The developed method is effective and facile for the fast quantification of complex TAGs in pistachio samples at high selectivity.

Direct Comparison of 18 Carbon n–3 and n–6 Fatty Acids at Equal Levels in an Oil Blend on Tissue Enrichment of Long-Chain Polyunsaturated Fatty Acid in Broiler Chickens

BackgroundOmega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) are of interest because of their health effects. However, most experiments use natural oils and are confounded by PUFA concentrations and other fatty acids (FAs) that impact biosynthesis of the very long-chain derivatives (VLC). ObjectivesTo directly compare the effect of 18 C n-3 or n-6 FA fed at similar rates on their elongation and desaturation to VLC PUFA and their incorporation into tissues. MethodsOil blends that substituted ∼23% points of stearidonic acid (SDA) with alpha-linolenic acid (ALA), gamma-linolenic acid (GLA), or linoleic acid (LA) while minimizing differences in other FA were prepared. COBB500 broilers were fed the oil blends at 1.25% of the diet from day 14–35 age. ResultsThere was greater enrichment of VLC PUFA in breast, thigh, liver, and plasma when diets were supplemented with high-SDA and high-GLA oil blends than high-ALA and high-LA oil blends. The efficiency of VLCn-3 PUFA synthesis from SDA and ALA was lower than the efficiency of VLCn-6 PUFA synthesis from GLA and LA, suggesting that the elongation and desaturation enzymes more efficiently utilized n-6 substrates. The efficiency of biotransformation of SDA to VLCn-3 PUFA was greater than that of high-ALA, and synthesis of VLCn-6 PUFA from GLA was higher than that of high-LA in breast, thigh, liver, and plasma. There were minimal effects on tissue-saturated and monounsaturated FA. ConclusionsThe high-SDA and high-GLA oil blends efficiently enriched tissues with their VLC-PUFA more than high-ALA and high-LA treatments.

Maytansinol Functionalization: Towards Useful Probes for Studying Microtubule Dynamics.

Maytansinoids are a successful class of natural and semisynthetic tubulin binders, known for their potent cytotoxic activity. Their wider application as cytotoxins and chemical probes to study tubulin dynamics has been held back by the complexity of natural product chemistry. Here we report the synthesis of long-chain derivatives and maytansinoid conjugates. We confirmed that bulky substituents do not impact their high activity or the scaffold's binding mode. These encouraging results open new avenues for the design of new maytansine-based probes.

Adenostemmoic acid B suppresses NO production by downregulating the expression and inhibiting the enzymatic activity of iNOS

Adenostemmoic acid B (AB) is a major compound found in Adenostemma lavenia ; it shows anti-melanogenic, anti-inflammatory, and cytotoxic activities. By modifying the 19th position (carboxy: involved in the avoidance of cytotoxicity) of AB, we succeed to separate these activities. Short-chain alkylation of the carboxy group enhanced anti-melanogenic activity, while long-chain alkylation (hydrophobic) resulted in the suppression of nitric oxide (NO) production and inducible NO synthase (iNOS) expression without anti-melanogenic activity. Re-modification of hydrophilic properties in these long-chain derivatives restored anti-melanogenic activity but did not suppress NO production. Unexpectedly, AB and derivatives with long chains linked by an anhydride bond were new iNOS inhibitors. These results suggest that AB modulates multiple physiological activities by regulating different targets, including iNOS. • Adenostemmoic acid B is a multipotential ingredient in Adenostemma lavenia. • Adenostemmoic acid B suppresses gene expression of tyrosinase (anti-melanogenesis) and iNOS (anti-inflammatory). • Adenostemmoic acid B and its derivatives with an anhydride bond inhibit iNOS enzyme activity.

Synthesis and evaluation of radiogallium-labeled long-chain fatty acid derivatives as myocardial metabolic imaging agents.

Since long-chain fatty acids work as the primary energy source for the myocardium, radiolabeled long-chain fatty acids play an important role as imaging agents to diagnose metabolic heart dysfunction and heart diseases. With the aim of developing radiogallium-labeled fatty acids, herein four fatty acid-based tracers, [67Ga]Ga-HBED-CC-PDA, [67Ga]Ga-HBED-CC-MHDA, [67Ga]Ga-DOTA-PDA, and [67Ga]Ga-DOTA-MHDA, which are [67Ga]Ga-HBED-CC and [67Ga]Ga-DOTA conjugated with pentadecanoic acid (PDA) and 3-methylhexadecanoic acid (MHDA), were synthesized, and their potential for myocardial metabolic imaging was evaluated. Those tracers were found to be chemically stable in 0.1 M phosphate buffered saline. Initial [67Ga]Ga-HBED-CC-PDA, [67Ga]Ga-HBED-CC-MHDA, [67Ga]Ga-DOTA-PDA, and [67Ga]Ga-DOTA-MHDA uptakes in the heart at 0.5 min postinjection were 5.01 ± 0.30%ID/g, 5.74 ± 1.02%ID/g, 5.67 ± 0.22%ID/g, and 5.29 ± 0.10%ID/g, respectively. These values were significantly lower than that of [123I]BMIPP (21.36 ± 2.73%ID/g). For their clinical application as myocardial metabolic imaging agents, further structural modifications are required to increase their uptake in the heart.

Serum levels of n-3 and n-6 polyunsaturated fatty acids in patients with systemic lupus erythematosus and their association with disease activity: a pilot study

Objective Polyunsaturated fatty acids (PUFAs) may modulate the inflammatory process in systemic autoimmune diseases, including systemic lupus erythematosus (SLE). The aim of this study was to assess the serum concentrations of essential 18-carbon PUFAs and their long-chain derivatives in patients with SLE and healthy controls, and to analyse their associations with laboratory and clinical features of the disease. Method n-6 and n-3 PUFA composition was assessed in the sera of 30 SLE patients and 20 healthy controls using gas chromatography–mass spectrometry. We investigated the associations between PUFAs and disease activity measured with Systemic Lupus Erythematosus Activity Index (SLEDAI) scores, erythrocyte sedimentation rate, C-reactive protein, complement C3 and C4 concentrations, anti-nuclear antibody (ANA) titre, anti-double-stranded DNA (anti-dsDNA) antibody concentration, and medications. Results Serum linoleic acid (LA) and α-linolenic acid concentrations were significantly higher in SLE patients compared with healthy controls. LA concentration correlated positively with the ANA titre and corticosteroid doses; eicosapentaenoic acid (EPA) and docosahexaenoic acid correlated inversely with anti-dsDNA antibody concentration. Patients treated with immunosuppressants had significantly lower concentrations of LA, arachidonic acid, and EPA. Conclusion Both n-6 and n-3 PUFA precursors can participate in the inflammatory process in SLE patients. The mechanism of the PUFA metabolism disturbance needs further exploration.

Experimental investigation on fast pyrolysis of freshwater algae. Prospects for alternative bio-fuel production

Several technologies have been developed with the aim of obtaining fuels from algae. In the present work, the fast pyrolysis of three different types of microalgae (Botryococcus braunii, Spirulina platensis, and Pithophora sp.) is investigated focusing on the quality and yield of the liquid product as a potential biofuel. The characterization of microalgae shows an elevated content of lipids in Botryococcus braunii, higher levels of proteins in Spirulina, and an equal number of proteins and carbohydrates in Pithophora sp. A fixed bed reactor, connected to a vacuum system, and nitrogen as inert gas flow are used in the pyrolysis experiments at 300, 400, 500, and 600 °C. At 500 °C, Botryococcus braunii produces the maximum amount of pyrolytic oil (65% yield) while Spirulina and Pithophora sp. affords the greatest amount at 600 °C, in 45% and 28% yield, respectively. Gas chromatography-mass spectrometry (GC–MS) analysis of the Botryococcus braunii-derived oils shows a high content of long-chain derivatives of alcohols, carboxylic acids, and unsaturated hydrocarbons. On the other hand, Spirulina-derived oil consists mostly of nitrogenated compounds while oil from Pithophora sp. is composed of oxygenated and/or nitrogenated products, depending on the reaction temperature. The measured higher heating value (HHV) of Botryococcus braunii-derived oil produced at 500 °C is 45 MJ/kg and this bio-oil could be used as a feedstock for fuel production after chemical upgrading to decrease the oxygen content (6.59 wt%).

The effect of a duodenal-jejunal bypass liner on lipid profile and blood concentrations of long chain polyunsaturated fatty acids

Duodenal-jejunal bypass liners (DJBLs) prevent absorption in the proximal small intestine, the site of fatty acid absorption. We sought to investigate the effects of a DJBL on blood concentrations of essential fatty acids (EFAs) and bioactive polyunsaturated fatty acids (PUFAs). Sub-study of a multicentre, randomised, controlled trial with two treatment groups. Patients aged 18-65 years with type-2 diabetes mellitus and body mass index 30-50kg/m2 were randomised to receive a DJBL for 12 months or best medical therapy, diet and exercise. Whole plasma PUFA concentrations were determined at baseline, 10 days, 6 and 11.5 months; data were available for n=70 patients per group. Weight loss was significantly greater in the DJBL group compared to controls after 11.5 months: total body weight loss 11.3±5.3% versus 6.0±5.7% (mean difference [95% CI]=5.27% [3.75, 6.80], p<0.001). Absolute concentrations of both EFAs, linoleic acid and α-linolenic acid, and their bioactive derivatives, arachidonic acid, eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid, were significantly lower in the DJBL group than in the control group at 6 and 11.5 months follow-up. Total serum cholesterol, LDL-cholesterol and HDL-cholesterol were also significantly lower in the DJBL group. One year of DJBL therapy is associated with superior weight loss and greater reductions in total serum cholesterol and LDL-cholesterol, but also depletion of EFAs and their longer chain derivatives. DJBL therapy may need to be offset by maintaining an adequate dietary intake of PUFAs or by supplementation. ClinicalTrials.gov Identifier NCT02459561.

Gamma-Linolenic and Pinolenic Acids Exert Anti-Inflammatory Effects in Cultured Human Endothelial Cells Through Their Elongation Products.

Omega-3 fatty acids (FAs) from oily fish reduce cardiovascular disease. This may be partly due to modulation of endothelial cell (EC) inflammation. Fish stocks are declining and there is a need for sustainable alternative FAs. Gamma-linolenic acid (GLA) and pinolenic acid (PLA) are plant-derived FAs, which can fulfil this role. EA.hy926 cells are exposed GLA and PLA prior to stimulation with tumor necrosis factor (TNF)-α. GLA and PLA are incorporated into ECs, resulting in increases in long-chain derivatives produced by elongase 5, dihomo-gamma-linolenic acid (DGLA), and eicosatrienoic acid (ETA). Both GLA and PLA (50µm) decrease production of soluble intercellular adhesion molecule-1 (sICAM-1), monocyte chemoattractant protein 1 (MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES). However, decreases in these mediators are not seen after pre-treatment with GLA or PLA in elongase 5 silenced EA.hy926 cells. DGLA and ETA (10µm) decrease EC production of sICAM-1, MCP-1, RANTES, and IL-6. All FAs reduce adhesion of THP-1 monocytes to EA.hy926 cells. Both PLA (50µm) and ETA (10µm) decrease NFκBp65 phosphorylation. These effects suggest potential for GLA, PLA and their long-chain derivatives, DGLA and ETA, as sustainable anti-inflammatory alternatives to fish-derived FAs.

A new abietane-type diterpenoid and a new long-chain alkenone from fungus Daldinia sp. TJ403-LS1

A new abietane-type diterpenoid, dalterpenoid A (1), a new long-chain alkenone derivative, (3E,5E,10E)-8-hydroxytrideca-3,5,10,12-tetraen-2-one (2), together with six known compounds (3–8), namely epi-guaidiol A (3), xylaranol A (4), daldinone C (5), trans-3,4-dihydroxy-3,4-dihydro-anofinic acid (6), (R)-6-hydroxymellein (7), helicascolide A (8), were obtained from fungus Daldinia sp. TJ403-LS1, which was originally isolated from roots of the medicinally valuable plant Anoectochilus roxburghii. The structures of compounds 1 and 2 were established based on widespread spectroscopic methods, mainly including 1D & 2D NMR and HRESIMS analyses, and the absolute configuration of 1 was further confirmed by electronic circular dichroism (ECD) calculation. All new compounds were tested for the in vitro cytotoxicity against five human cancer cell lines.

Combined study of source, environmental monitoring and fate of branched alkylphenols: The chain length matters.

Alkylphenols (APs) are chemicals of largely anthropogenic origin. Longer chain derivatives like 4-nonylphenol (4NP) or 4-tert.-octylphenol (4tOP) are mainly used for the production of alkylphenol ethoxylates, while short chain alkylphenols (SCAPs) can be applied during the production of phenolic or epoxide resins that are used in paint, glue or adhesive formulations. The source, environmental distribution and fate of 4NP and 4tOP were thoroughly demonstrated leading to growing concerns regarding their endocrine properties. Although, SCAPs are also expected to entail risks to the aquatic environment, only few studies dealt with the identification of possible sources or environmental concentrations thereof.In order to evaluate the role of resin-based building materials as a possible source of 4-tert.-butylphenol (4tBP), 4-tert.-pentylphenol (4tPP), 4tOP and 4NP, 18 formulations were tested. Furthermore, AP concentrations of four wastewater treatment plants (WWTPs) and 50 surface waters were analyzed to assess and compare environmental concentrations and the discharge of APs depending on their chain length. 4tBP was the dominant AP in analyzed building materials with concentrations up to 320 g kg−1. Furthermore, APs were detected in all WWTPs and waterbodies. 4NP was the dominant AP in most surface water and WWTP samples ranging from <LOQ-0.5 μg L−1 and <LOQ-2.34 μg L−1, respectively, whereas 4tPP was rarely detected over all samples. Observed detection patterns of 4tBP in surface waters indicated different entrance pathways and hence, different sources compared to 4NP and 4tOP. Furthermore, WWTP samples and accompanying transformation studies pointed towards rapid biotransformation of 4tBP, explaining low environmental concentrations.

Synthesis of chrysin derivatives and screening of antitumor activity

A series of aromatic or long-chain chrysin derivatives (1–10) were synthesized by esterification of chrysin and acyl chloride. The chemical structures of these compounds were determined by mass spectrum (MS), 1H NMR, and 13C NMR spectra. Though aromatic chrysin derivatives (1–9) with a rigid structure were hard to dissolve in common organic solvents, the long-chain chrysin derivative (10) with a flexible structure had better solubility, and its anticancer activity (IC50 = 14.79 μmol/L) against liver cancer cell lines was 5.4 times better than chrysin (IC50 = 74.97 μmol/L), which showed superposition of pharmacological activity.

Imparting Photo-responsive Function to Thermo-responsive Iridescent Emulsions

In our previous paper, we reported that thermo-responsive emulsions can be prepared based on a long-chain amidoamine derivative (C18AA) and tetraoctylammonium bromide (TOAB), and that the C18AA + TOAB emulsions developed a characteristic interference color in a narrow temperature range. However, the coloration of the original C18AA + TOAB at room temperature exhibited poor brightness. In the present study, we show that the addition of NaOH is effective in both lowering the coloration temperature and improving the brightness of C18AA + TOAB emulsion considerably. Furthermore, we demonstrate that photo-response function can be imparted to C18AA + TOAB iridescent emulsions by introducing a photochromic naphthopyran derivative (Pyran) that reversibly changes from white to yellow upon UV irradiation. The C18AA + TOAB emulsions containing Pyran shows a dual stimuli-responsive iridescent property, and the emulsion color is controllable and reversible through both UV irradiation and temperature.

Synthesis and Pharmacological Valorization of Derivatives of 4-Phenyl-1,5-Benzodiazepin-2-One.

The objective of our work is to make a pharmacological study of molecules derived from 4-phenyl-1,5-benzodiazepin-2-one carrying long chains so that they have a structure similar to surfactants, with the benzodiazepine as a hydrophilic head and a carbon chain as a hydrophobic tail. First, we studied the acute toxicity of the above mentioned 4-phenyl-1,5-benzodiazepin-2-one derivatives. This study was conducted according to OECD 423 guidelines in female mice and revealed that these compounds are nontoxic. We then assessed the psychotropic effects of our products on the central nervous system (CNS). The results obtained show that 4-phenyl-1,5-benzodiazepin-2-one has no sedative effect at therapeutic doses of 100 and 200 mg/kg. On the other hand, its long-chain derivatives possess them. Moreover, all these products have no cataleptic and hypnotic effects at the doses studied. But at 100 mg/kg, these compounds all have the ability to significantly prolong the hypnotic effect of thiopental sodium.

Liquid-Crystalline Properties of Thioesters

An extension of a new method for forming thioesters with mesomorphic properties has been described, whereby the treatment of aryl tert-butylthioethers with long-chain acid chlorides in the presence of bismuth triflate afforded simple derivatives in good yields. This method in the case of 1-cyanoazulenes was, however, complicated by a competitive Friedel–Crafts-type acylation side reaction at the 3-position. Long-chain derivatives of cyanobiphenyl attached through a thioester linkage exhibited mesophases comparable with their ester analogues. The use of shorter chains to decorate the cyanobiphenyl moiety did not produce mesophasic behaviour, unlike their ester analogues. The cyanobiphenyl derivatives showing mesophasic behaviour were studied by small-angle X-ray diffraction, showing alignment for molecules possessing a smectic A phase. It was found that the layer spacing in the smectic A phase was ~1.5 times the length of the molecule, owing to antiparallel pairing arising from π-stacking between neighbouring units. Calculations suggest these derivatives should exhibit large dielectric anisotropy; however, instability made an exact value difficult to determine. For potential use in a liquid crystal display (LCD), the thioester holds some promise, although this may be limited by the relative stability of the thioester functionality.

Self-organisation processes and phase-structural states in hybrid metal-mesogenic nanosystems

ABSTRACTHybrid nanosystems including silver and copper and long-chain mesogenic derivatives of alkylcyanobiphenyls have been obtained by low temperature vacuum co-condensation of reagent vapors on cooled surfaces of quartz, KBr, CaF2 or polished copper under molecular beam conditions. Controlled thermal treatment of the samples allowed the directed formation of metal nanoparticles of definite size from 2 up to 100 nm. It was shown that manner of temperature treatment and molecular self-organisation of different liquid crystalline phases controlling of the size and morphology of nanoparticles and their aggregates formed in the system. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) data of the samples show the formation of orientationally ordered structures in nematic mesophases. Formation of flat 2D-aggregates has been found in layered smectic mesophases Optical absorbance spectra of silver/4-pentyl-4-cyanobiphenyl (Ag/5СВ) and copper/4-pentyl-4-cyanobiphenyl (Cu/5CB) samples encapsulated in polymer poly-para-xylylene at 300 K contain characteristic bands of plasmonic absorbance of metal nanoparticles at 420–440 nm and 560–600 nm. Rising of metal concentration in the sample led to the performable growth of rod-like metal particles with anisometric ratio l/d>20 and intensive absorbance at higher wavelengths (λ ≥ 650 nm)

A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc-CH2CH2-S-S-CH2CH2-Fc.

Facile synthetic procedures to synthesize a series of difficult-to-obtain mercaptoalkylferrocenes, namely, Fc(CH2)nSH, where n = 1 (1), 2 (2), 3 (3), or 4 (4) and Fc = Fe(η(5)-C5H5)(η(5)-C5H4), are reported. Dimerization of 1-4 to the corresponding disulfides 19-22 was observed in air. Dimer 20 (Z = 2) crystallized in the triclinic space group P1̅. Dimers 20-22 could be reduced back to the original Fc(CH2)nSH derivatives with LiAlH4 in refluxing tetrahydrofuran. Density functional theory (DFT) calculations showed that the highest occupied molecular orbital of 1-4 lies exclusively on the ferrocenyl group implying that the electrochemical oxidation observed at ca. -15 < Epa < 76 mV versus FcH/FcH(+) involves exclusively an Fe(II) to Fe(III) process. Further DFT calculations showed this one-electron oxidation is followed by proton loss on the thiol group to generate a radical, Fc(CH2)nS(•), with spin density mainly located on the sulfur. Rapid exothermic dimerization leads to the observed dimers, Fc(CH2)n-S-S-(CH 2)nFc. Reduction of the ferrocenium groups on the dimer occurs at potentials that still showed the ferrocenyl group ΔE = Epa,monomer - Epc,dimer ≤ 78 mV, indicating that the redox properties of the ferrocenyl group on the mercaptans are very similar to those of the dimer. (1)H NMR measurements showed that, like ferrocenyl oxidation, the resonance position of the sulfhydryl proton, SH, and others, are dependent on -(CH2)n- chain length. Self-assembled monolayers (SAMs) on gold were generated to investigate the electrochemical behavior of 1-4 in the absence of diffusion. Under these conditions, ΔE approached 0 mV for the longer chain derivatives at slow scan rates. The surface-bound ferrocenyl group of the metal-thioether, Fc(CH2)n -S-Au, is oxidized at approximately equal potentials as the equivalent CH2Cl2-dissolved ferrocenyl species 1-4. Surface coverage by the SAMs is dependent on alkyl chain length with the largest coverage obtained for 4, while the rate of heterogeneous electron transfer between SAM substrate and electrode was the fastest for the shortest chain derivative, Fc-CH2-S-Au.

Synthesis, characterization and theoretical study of a new liquid crystal compound with an oxazepine core

A novel synthesis of heterocyclic liquid crystal compounds containing a seven-membered 1,3-oxazepine with terminal alkyloxy chains has been carried out. The molecular structures of these compounds were substantiated by FT-IR NMR elemental analysis. The relationship between the structures and the mesomorphic behaviours of their derivatives were investigated. The results showed that the formation of mesophases is strongly dependent on the type of core moiety. All compounds with oxazepinediones and oxazepanediones are non-mesogenic and only exhibit Cr1Cr2 upon cooling and heating. However, the SmA and N phases were observed in the 5,6-benzo [1,3] oxazepine-4,7-diones series of compounds. The study also revealed that the length of the alkyl chain has a significant effect on the liquid crystalline properties; the nematic phase can only observed in long-chain derivatives of 5,6-benzo [1,3] oxazepine-4,7-diones. Theoretical studies are in agreement with our result.