Simple Molecular Structure Research Articles

Thymoquinone: An edible redox-active quinone for the pharmacotherapy of neurodegenerative conditions and glial brain tumors. A short review.

There exist few efficient agents in the neurological and neurosurgical armamentarium for treatment of neurotrauma, refractory seizures and high grade glial tumors. Pathophysiological conditions of diverse neural injuries have converging common pathways including oxidative stress and apoptosis. Targeted therapies have been throughly investigated, but limited success has been achieved until now. Phytochemical drugs may provide easily achievable and cheap adjunctive sources. Thymoquinone is an edible quinone obtained from Nigella sativa seed oil and exerts powerful antiinflammatory, antioxidant and antitumor activities in experimental models. Recently emerging studies conducted with animal models suggest that thymoquinone - bearing a very simple molecular structure - significantly crosses the blood brain barrier and exerts neuromodulatory activities. Indeed, in animal studies, the following actions of thymoquinone were demonstrated: 1-Protection against ischemic brain damage. 2-Reduction of epileptic seizures and associated cerebral oxidative injury. 3-Reduction of morphine tolerance and associated oxidative brain damage. 4-Anxiolytic effects and reduction of immobility stress-associated cerebral oxidative injury. 5-Reduction of diabetes-induced cerebral oxidative stress, 6-Reduction of cerebral oxidative injuries induced by noxious exposures including toluene, lead and ionizing radiation. Substantial in vitro data suggest that thymoquinone may be beneficial in treatment of glial tumors. However, there is no clinical study investigating its antitumor effects. In fact, thymoquinone suppresses growth and invasion, and induces apoptosis of glial tumor cells via degrading tubulins and inhibiting 20S proteasome, telomerase, autophagy, FAK and metalloproteinases. A simple and easily available agent may be a promising adjunctive treatment option in neurological and neurosurgical practice.

Elevational Variation in Soil Amino Acid and Inorganic Nitrogen Concentrations in Taibai Mountain, China.

Amino acids are important sources of soil organic nitrogen (N), which is essential for plant nutrition, but detailed information about which amino acids predominant and whether amino acid composition varies with elevation is lacking. In this study, we hypothesized that the concentrations of amino acids in soil would increase and their composition would vary along the elevational gradient of Taibai Mountain, as plant-derived organic matter accumulated and N mineralization and microbial immobilization of amino acids slowed with reduced soil temperature. Results showed that the concentrations of soil extractable total N, extractable organic N and amino acids significantly increased with elevation due to the accumulation of soil organic matter and the greater N content. Soil extractable organic N concentration was significantly greater than that of the extractable inorganic N (NO3−-N + NH4+-N). On average, soil adsorbed amino acid concentration was approximately 5-fold greater than that of the free amino acids, which indicates that adsorbed amino acids extracted with the strong salt solution likely represent a potential source for the replenishment of free amino acids. We found no appreciable evidence to suggest that amino acids with simple molecular structure were dominant at low elevations, whereas amino acids with high molecular weight and complex aromatic structure dominated the high elevations. Across the elevational gradient, the amino acid pool was dominated by alanine, aspartic acid, glycine, glutamic acid, histidine, serine and threonine. These seven amino acids accounted for approximately 68.9% of the total hydrolyzable amino acid pool. The proportions of isoleucine, tyrosine and methionine varied with elevation, while soil major amino acid composition (including alanine, arginine, aspartic acid, glycine, histidine, leucine, phenylalanine, serine, threonine and valine) did not vary appreciably with elevation (p>0.10). The compositional similarity of many amino acids across the elevational gradient suggests that soil amino acids likely originate from a common source or through similar biochemical processes.

Simple molecular structure design of iridium(III) complexes: Achieving highly efficient non-doped devices with low efficiency roll-off

To construct efficient emitters suitable for non-doped devices and deeply understand the relationship between structures and performances, we designed and synthesized two heteroleptic iridium(III) complexes based on 1,2-diphenyl-1H-benzoimidazole (PBI) ligands whose substituents are varied simply from methyl (complex 2) to tert-butyl groups (complex 3). The parent complex 1 with non-substituent on PBI ligand has also been presented for a better comparison. Their photophysical, electrochemical and electroluminescent (EL) performances are investigated systematically. Despite their structural modification, all complexes exhibit almost identical emission and excited-state characters, which are rationalized by the quantum-chemical calculations. However, the obvious differences on device performances are found. Non-doped device employing 3 as emitting layer displays the highest EL performance with maximum current efficiency (ηc, max) of 18.6 cd A−1 and power efficiency (ηp, max) of 16.2 lm W−1 accompanied by low efficiency roll-off values, which is much higher than those of complexes 1 and 2. The obtained results herein suggest that introduction of the simple substituent into PBI ligand is an effective and feasible approach to develop highly efficient non-doped phosphors.

Self-assembly of aromatic biscarbamate gelators: effect of spacer length on the gelation and rheology

Low molecular weight biscarbamate organogelators (LMWBGs) with simple molecular structures that could gel different types of organic solvents were synthesized. The LMWBGs were composed of a long hydrophobic tail of linear fatty alcohol (C8–C18) and an aromatic core and could gel organic solvents such as xylene, toluene, NMP, cyclohexanol and chlorobenzene at a concentration of 10–15 mg/mL. Gelation studies indicated that the alkyl chain length residues did not affect the gelation time which was generally around 10–15 min leading to opaque gels in all the solvents. The gels in p-xylene were studied by FTIR spectroscopy and differential scanning calorimetry (DSC) for the nature of the interactions between the gelators and the solvent. FTIR spectroscopic studies revealed that hydrogen bonding and van der Waals interactions were the driving forces for the formation of the gels, while solid-state UV–visible studies revealed the existence of π–π interaction in the xerogel. The gel melting temperatures were found to decrease and then increase with increasing alkyl chain length as observed in DSC. The microscopic observations (FE-SEM) suggested that the gelator molecules self-assembled leading to nano- and microfibres in the turbid gel, and as the alkyl chain length increased, the width of the fibres increased. Rheological studies evinced the viscoelastic nature of the soft gels viscoelasticity increased with increasing gelator concentration, while fluidity increased with increasing chain length. The X-ray diffraction analysis revealed that in the xerogels from p-xylene the molecules aggregated into a layered structure. This study on the influence of alkyl side chains shows that hydrogen bonding and van der Waals interactions play a significant role in the morphology of such self-assembled structures.

A simple oxazoline as fluorescent sensor for Zn2 + in aqueous media

2-(2′-Hydroxyphenyl)-2-oxazoline is shown to be a highly-selective Zn2+ sensor with very simple molecular structure. It demonstrates an excellent fluorescence “turn-on” response to Zn2+ in aqueous medium even in the presence of other competing anions and detection capability for studying the distribution of Zn2+ in living human HeLa cells as a proof-of-concept.

Combined aggregation induced emission (AIE), photochromism and photoresponsive wettability in simple dichloro-substituted triphenylethylene derivatives.

A dichloro-substituted triphenylethylene derivative (TrPECl2) with aggregation-induced emission (AIE), photochromism and photoresponsive wettability has been synthesized. The new compound shows fast-response photochromic behaviour with good ON/OFF repeatability by utilizing a proposed stilbene-type intramolecular photocyclization in the solid state. Compared with the more usual diphenylethylene derivatives, the photochromic properties of the triphenylethylene derivative are much more striking and easier to achieve. The triphenylethylene derivative also displays AIE properties leading to strong fluorescence in the solid state. Therefore, both the ultraviolet-visible absorption and fluorescence emission are drastically changed during the photochromic processes. Furthermore, the morphology of the TrPECl2 microcrystalline surface could be controlled by irradiation. The wettability of the surface could be drastically decreased with contact angles of a water droplet changing from 73° to 118°. The triphenylethylene derivative with a simple molecular structure is, therefore, attractive for multifunctional materials.

C–H⋯O (ether) hydrogen bonding along the (110) direction in polyglycolic acid studied by infrared spectroscopy, wide-angle X-ray diffraction, quantum chemical calculations and natural bond orbital calculations

Polyglycolic acid (PGA), a biodegradable polyester with a simple molecular structure, shows an abnormally high melting point of 220 °C which is the highest among biopolyesters.

Performance characteristics of a membraneless solar responsive photocatalytic fuel cell with an air-breathing cathode under different fuels and electrolytes and air conditions

In this work, a membraneless photocatalytic fuel cell (PFC) with a solar responsive photoanode and an air-breathing cathode was developed to simultaneously degrade the wastewater and generate electricity. The performance characteristics of the developed PFC was examined for the real application purpose. Particular attention was paid to investigate the effect of the fuel and electrolyte types on the cell performance. Experimental results showed that the alkaline electrolyte yielded the maximum power density of 4.1mWcm−2, which was much better than the neutral electrolyte with the maximum power density of 0.5mWcm−2. Long-term performance measurements also showed that the cell performance was rather stable under the alkaline electrolyte but dramatically reduced under the neutral electrolyte in the 3-hour constant current density operation. Regarding the fuel types, the PFC exhibited appreciable performance for both alcohols and saccharides. Methanol and glycerol produced the maximum power densities of 4.08 and 2.58mWcm−2, while D-glucose and D-xylose generated the maximum power densities of 3.92 and 3.67mWcm−2, respectively. The difference in the cell performance can be attributed to the difference in the molecular structure, i.e., the fuel with a simpler molecular structure and a shorter carbon chain could yield better performance. Besides, the PFCs also showed favorable performances in some complex wastes, such as artificial sewage, Coca Cola and urine. For the air-breathing cathode design, the oxygen concentration effect on the PFC performance was also studied. It was found that increasing the oxygen concentration from 5% to pure oxygen led to the improvement of the maximum power density from 3.5 to 5.2mWcm−2.

Facile Synthesis of a Furan-Arylamine Hole-Transporting Material for High-Efficiency, Mesoscopic Perovskite Solar Cells.

A novel hole-transporting molecule (F101) based on a furan core has been synthesized by means of a short, high-yielding route. When used as the hole-transporting material (HTM) in mesoporous methylammonium lead halide perovskite solar cells (PSCs) it produced better device performance than the current state-of-the-art HTM 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD). The F101-HTM-based device exhibited both slightly higher Jsc (19.63 vs. 18.41 mA cm(-2) ) and Voc (1.1 vs. 1.05 V) resulting in a marginally higher power conversion efficiency (PCE) (13.1 vs. 13 %). The steady-state and time-resolved photoluminescence show that F101 has significant charge extraction ability. The simple molecular structure, short synthesis route with high yield and better performance in devices makes F101 an excellent candidate for replacing the expensive spiro-OMeTAD as HTM in PSCs.

Efficient hole-transporter for phosphorescent organic light emitting diodes with a simple molecular structure

N,N-diphenyl-4-(quinolin-8-yl)aniline (SQTPA), which composes a triphenylamine group and a quinoline group, has been synthesized and employed as a hole-transporter in phosphorescent OLEDs. It has been proved that SQTPA has efficient hole-transport property withahole-mobilityof3.60×10−5cm2/Vs at the electric field of 800(V/cm)1/2, which is higher than that of NPB (1.93×10−5cm2/Vs). Blue, orange and green phosphorescent OLEDs have been fabricated based on FIrpic, Ir(2-phq)3, Ir(ppy)3 with typical structures by using SQTPA as the hole-transporter. The SQTPA-based devices show maximum external quantum efficiencies and power efficiencies of 17.5%, 32.5lm/W for blue, 12.3%, 20.5lm/W for orange and 20.3%, 64.5lm/W for green. The performances of SQTPA-based devices are much better than that of NPB-based phosphorescent OLEDs with similar structures. Thought of its very simple molecular structure and easy synthetic route, SQTPA should be an efficient hole-transporter for phosphorescent OLEDs.

The stabilization of tannery sludge and the character of humic acid-like during low temperature pyrolysis.

Tannery sludge contained plenty of organic matter, and the organic substance stability had direct impact on its derived chars' utilization. In this paper, the stabilization of tannery sludge and the variation of humic acid-like (HAL) extracted by different methods were investigated in a magnetic stirring reactor under low temperature pyrolysis of 100-400 °C. Results showed that the aromatic structure of pyrolysis chars increased with the increase of temperature and time. The char contained highly aromatic structure and relatively small dissolved organic matters (DOM) at 300 °C. The similar behaviors appeared in two HAL series by different extraction methods. The N content, H/C value, and aliphatic structures of HAL decreased with the increase of pyrolysis temperature, while the C/N value and aromatic structures increased with the rise of pyrolysis temperature. The composition and functional groups of HAL were similar with the purchased humic acid (HA). The fluorescence spectra revealed that two main peaks were found at Ex/Em = 239/363-368 nm and 283/359-368 nm in each HAL series from raw and 100 °C pyrolysis tannery sludge, representing a protein-like matter. The new peak appeared at Ex/Em = 263-283/388 nm in each HAL series from 200 °C pyrolysis tannery sludge-represented humic acid-like matter. The fluorescence intensity increased strongly compared to the other two peak intensity. Therefore, the humification of organic matter was increased by pyrolyzing. Notably, the HAL from 200 °C pyrolysis tannery sludge contained simple molecular structure, and the polycondensation increased but with a relative lower humification degree compared to soil HAL and purchased HA. Therefore, the sludge needs further oxidation. The humic substance was negligible by direct extraction when the temperature was 300 and 400 °C.

Oxidation and reduction of substances in solid, liquid, and gaseous states in an electrochemical reactor based on zirconia

The oxidation and reduction of organic compounds in the gaseous, liquid, and solid states were studied using a Delta Plus XP isotope mass spectrometer. The oxidation and reduction were performed for substances with simple and complex molecular structures: methane (natural gas standard RM 8561 HGS3), ethanol, pyridine, benzyl alcohol, n-undecane, and cysteine; the reduction was performed for water and methanol. Based on these data, it was concluded that the complex organic compounds were almost completely oxidized, while water and oxygen-containing organic substances were completely reduced in the developed electrochemical solid-electrolyte reactor (SER). The use of this reactor in the optimum mode did not change the isotope composition of carbon and hydrogen in the analytes. SER can successfully replace the oxidation and reduction reactors used in isotope-ratio mass spectrometry.

Predicting storage-lipid water partitioning of organic solutes from molecular structure.

Partitioning to storage fat is the major process for bioaccumulation of many neutral organic chemicals. In this work, we evaluated the performance of four predictive models, ABSOLV, COSMOtherm, KOWWIN, and SPARC to calculate storage lipid-water partition coefficients. In a first step of the validation, we used over 300 literature data for chemicals with relatively simple molecular structures. For these compounds the overall performance was similar for all models with a root-mean-square error (rmse) between 0.45 and 0.61 log units. Clear differences became visible in the second validation step where a subset with only H-bond-donor compounds was used. Here, COSMOtherm and SPARC performed clearly better with an rmse of 0.35 and 0.42 log units, respectively, compared to ABSOLV and KOWWIN with an rmse of 0.91 and 0.85 log units, respectively. The last step in our validation was a comparison with experimental values for 22 complex, multifunctional chemicals (including pesticides, hormones, mycotoxins) that we measured specifically for this validation purpose. For these chemicals, predictions by all models were less accurate than those for simpler chemicals. COSMOtherm performed the best (rmse 0.71 log units) while the other methods showed considerably poorer results (rmse 1.29 (ABSOLV), 1.25 (SPARC), and 1.62 (KOWWIN) log units).

Gelation by Novel Aprotic Low-molecular-mass Organic Gelators Based on a Gemini 4-[2-(Perfluorobutyl)ethylthio]phenoxy Unit

Abstract We found novel aprotic low-molecular-mass organic gelators (LMOGs) with simple molecular structure based on a gemini 4-[2-(perfluorobutyl)ethylthio]phenoxy unit. These aprotic LMOGs formed a physical gel with a thermally reversible sol–gel phase transition in a wide variety of alcoholic and polar solvents such as 1-octanol and propylene carbonate at concentrations below 1 wt %.

Photocatalytic degradation of recalcitrant organic pollutants in water using a novel cylindrical multi-column photoreactor packed with TiO2-coated silica gel beads

A novel cylindrical multi-column photocatalytic reactor (CMCPR) has been developed and successfully applied for the degradation of methyl orange (MO), amoxicillin (AMX) and 3-chlorophenol (3-CP) in water. Due to its higher adsorption capacity and simpler molecular structure, 3-CP compared with MO and AMX obtained the highest photodegradation (100%) and mineralization (78.1%) after 300-min photocatalytic reaction. Electrical energy consumption for photocatalytic degradation of MO, AMX and 3-CP using CMCPR was 5.79×104, 7.31×104 and 2.52×104kWhm−3 order−1, respectively, which were less than one-thousand of those by reported photoreactors. The higher flow rate (15mLmin−1), lower initial concentration (5mgL−1) and acidic condition (pH 3) were more favorable for the photocatalytic degradation of MO using CMCPR. Five repetitive operations of CMCPR achieved more than 97.0% photodegradation of MO in each cycle and gave a relative standard deviation of 0.72%. In comparison with reported slurry and thin-film photoreactors, CMCPR exhibited higher photocatalytic efficiency, lower energy consumption and better repetitive operation performance for the degradation of MO, AMX and 3-CP in water. The results demonstrated the feasibility of utilizing CMCPR for the degradation of recalcitrant organic pollutants in water.

Engineering fused coumarin dyes: a molecular level understanding of aggregation quenching and tuning electroluminescence via alkyl chain substitution

Simple molecular structures capable of emitting over the entire visible range are still a challenge. Planar molecular structures have the drawback of fluorescence quenching in the solid state thus limiting their application fields. Combining long range excimer/exciplex emissions with a compound emission have been used to get white light. In this work, a series of new coumarin derivatives having a planar structure have been synthesized and characterized. The effects of systematic variation in alkyl chain functionalization providing morphological variations that permit interesting solid state emitting properties have been discussed simultaneously with electrochemical behavior and OLED (organic light emitting diode) device applications. Carbon chains containing 0–16 carbon atoms have been studied in order to conclude the results that systematic changes in alkyl group substitution can be utilized as a tool to tune the emitting color of these planar coumarins. Alkyl chains were introduced by O-acylation and O-benzoylation reaction on the hydroxyl group of parent coumarin 5. Thus the present strategy is also helpful in establishing a template to control the unproductive interchromophore electronic couplings. Solid state fluorescence properties support the crystal studies. Theoretical studies are also in agreement with experimental data. Electroluminescence of Device 2 with a turn on voltage (Von) around 5–6 V having s-CBP doped with 1% of 8 having alkyl substitution of 2-carbons is found to exhibit white emission with CIE co-ordinates of (0.29, 0.34) which is close to white emission while the alkyl substitution of 14-carbons (compound 17) in Device 7 (Von = 7 V) exhibited green emission. Thus a strategy helpful to tune the electroluminescence has been discussed.

How to determine the adsorption energy of the surfactant’s hydrophilic head? How to estimate easily the surface activity of every simple surfactant?

A definite way to determine the adsorption energy of the surfactant’s hydrophilic head on the air water interface is presented. For this purpose, the Davies adsorption theory and the most advanced version of Helfand–Frish–Lebowitz adsorption theory were applied to the surface tension isotherms of homologous series of sodium alkyl sulfate (CnH2n+1SO4Na, n=7–12), thus deriving the equilibrium adsorption constant, the cross-sectional area of the surfactant molecule, the interaction coefficient and the cohesion constant versus the number of the carbon atoms into the alkyl sulfate molecule. Thus, the total adsorption energy of each particular homolog was calculated in line with the latest development of the adsorption theory, thus calculating the dimensionless adsorption energy of the hydrophilic head Ehead/kBT. In our particular case (SO4−) we calculated Ehead/kBT=−2.79, which indicates the strong propensity of the SO4− to be surrounded by water molecules. The procedure for calculation Ehead/kBT does not depend on the charge of the hydrophilic head. Similarly, we calculated Ehead/kBT of another six well known in the literature hydrophilic heads (COOH, OH, DMPO, DEPO, N(CH3)3+, and NH3+), indicating that the adsorption energy of the CH2 group depends slightly on the type of the hydrophilic head, but it affects substantially the adsorption energy of the whole surfactant molecule. Finally, we defined and validated a parameter called adsorption capacity of surfactants with simple molecular structure, for easy estimation of their surface activity. Linear dependence between the CMC of ionic surfactants and their adsorption capacity was established.

Photoluminescence optimization of BCNO phosphors synthesized using citric acid as a carbon source

Citric acid was used as carbon source for the optimization of the photoluminescence (PL) performance of boron carbon oxynitride (BCNO) phosphor. Citric acid was chosen as an alternative carbon source because of its simple molecular structure, low decomposition temperature, relative inexpensiveness, and environmental friendliness. The prepared sample exhibited a single, homogeneous, and broad photoluminescence emission band whose peak varied from near-UV (400nm) to yellow-visible (500nm) upon excitation at 365nm. The effects of varying the synthesis temperature, molar ratio of the carbon/boron and nitrogen/boron sources, and addition of SiO2 nanoparticles on the PL properties were also studied. The optimized BCNO phosphors may find potential use in white LED applications.

Recent data on obesity research: β-aminoisobutyric acid.

The world-wide epidemic of obesity is now affecting up to a third of the adult population. Research attempting to contribute to management of this health scourge has been recently refocused on the essential role of physical activity. Muscle activity induces a dramatic increase in transcription of the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). This protein is a regulator of mitochondrial biogenesis and function. Very recently, in 2014 it was revealed that the mediator of this metabolic process is a low molecular myokine, the beta- aminoisobutyric acid (BAIBA). This compound with a simple molecular structure has a key metabolic role: it converts the cells of white adipose tissue into brown fat. The brown adipocytes contain a protein thermogenin. This substance turns off the energy stores, among others the adenosine triphosphate (ATP), thereby accelerating the breakdown of lipids into heat, water and CO2. We may be at the threshold of new and effective management of obesity. The world eagerly expects to see how the BAIBA will compare with other recently reported agents to fight the overweight (Fig. 2, Ref. 6).

Design, synthesis and biological evaluation of 3,5-disubstituted 2-amino thiophene derivatives as a novel class of antitumor agents

In search of new compounds with strong antiproliferative activity and simple molecular structure, we designed a novel series of agents based on the 2-amino-3-alkoxycarbonyl/cyano-5-arylethylthiophene scaffold. The presence of the ethyl spacer between the 2′,5′-dimethoxyphenyl and the 5-position of the thiophene ring, as well as the number and location of methoxy substitutents on the phenyl ring, played a profound role in affecting the antiproliferative activity. Among the synthesized compounds, we identified the 2-amino-3-cyano-[2-(2,5-dimethoxyphenyl)ethyl] thiophene 2c as the most promising derivative against a wide panel of cancer cell lines (IC50=17–130nM). The antiproliferative activity of this compound appears to correlate well with its ability to inhibit tubulin assembly and the binding of colchicine to tubulin. Moreover 2c, as determined by flow cytometry, strongly induced arrest in the G2/M phase of the cell cycle, and annexin-V and propidium iodide staining indicate that cell death proceeds through an apoptotic mechanism that follows the intrinsic mitochondrial pathway.