Preparation and crystal structures of the Ce(IV) β-diketonates, [Ce(tmhd)4] and [Ce(pmhd)4] (tmhd =2,2,6,6-tetramethylheptane-3,5-dionate and pmhd = 1-phenyl-5-methylhexane-1,3-dionate)

The cerium(IV) -diketonate compounds [Ce(-diket)₄] [where -diket = tmhd (2,2,6,6-tetramethylheptane-3,5-dionate) 1, pmhd (1-phenyl-5-methylhexane-1,3-dionate) 2] were prepared by reacting cerium(IV) ammonium nitrate [CAN; Ce(NH₄)₂(NO₃)₆] with the respective Na(-diket) compound in ethanol, and structurally characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group with a = 12.472(4), b = 19.972(5), c = 21.436(3) Å, = 97.05(7), = 90.16(2), = 106.55(3)°, V = 5076(2) ų, Z = 4, T = 150(2) K. Compound 2 crystallizes in the monoclinic space group P2₁/n. with a = 14.817(6), b = 17.123(6), c = 19.146(3) Å, = 105.46(4)°, V = 4682(3) ų, Z = 4, T = 150(2) K. Crystals of 1 contain two independent [Ce(tmhd)₄] molecules, with four chelating tmhd ligands bonded to each metal in a distorted dodecahedral arrangement; the cerium atom in 2 is also bonded to four chelating pmhd ligands but in this case the coordination geometry is closer to square antiprism. Both complexes are air and moisture stable. Sublimation studies reveal that 1 sublimes almost quantitatively, while 2 is comparatively involatile.     

The synthesis and X-ray structure of [Sr2(OSiPh3)4(NH3)5]·0.5C7H8

The title complex [Sr₂(OSiPh₃)₄(NH₃)₅]·0.5C₇H₈ was prepared by the reaction of strontium metal granules with triphenylsilanol in an ammoniacal-toluene solution at –40°C. It crystallizes in monoclinic space group P2₁/n with a = 14.465(3), b = 20.715 (6), c = 25.199(6) Å, = 95.98(2)°, and Z = 4. The complex has a dimeric structure with one terminal and three bridging triphenylsiloxy ligands, the remaining coordination sites being occupied by five ammonia molecules. The central Sr₂O₄N₅ moiety adopts a distorted M₂X₉ face-sharing bioctahedral arrangement.     

Isolation and structure elucidation of three glycosides and a long chain alcohol from Polianthes tuberosa Linn

Three glycosides and a long chain alcohol were isolated from the bulbs of Polianthes tuberosa, these were identified as 3,29-dihydroxystigmast-5-ene-3-O-beta-D-galactopyranoside (1), ethyl beta-D-galactopyranoside (2), ethyl-alpha-D-galactopyranoside (3), and 1-tricosanol (4). The structures were determined by extensive spectroscopic and chemical methods. All four isolated compounds were screened for their cytotoxicity, antibacterial and antifungal activities, none of the compounds showed any significant activity.     

Online preconcentration by electrokinetic supercharging for separation of endocrine disrupting chemical and phenolic pollutants in water samples

Online preconcentration using electrokinetic supercharging (EKS) was proposed to enhance the sensitivity of separation for endocrine disrupting chemical (methylparaben (MP)) and phenolic pollutants (2‐nitrophenol (NP) and 4‐chlorophenol (CP)) in water sample. Important EKS and separation conditions such as the concentration of BGE; the choice of terminating electrolyte (TE); and the injection time of leading electrolyte (LE), sample, and TE were optimized. The optimum EKS‐CE conditions were as follows: BGE comprising of 12 mM sodium tetraborate pH 10.1, 100 mM sodium chloride as LE hydrodynamically injected at 50 mbar for 30 s, electrokinetic injection (EKI) of sample at –3 kV for 200 s, and 100 mM CHES as TE hydrodynamically injected at 50 mbar for 40 s. The separation was conducted at negative polarity mode and UV detection at 214 nm. Under these conditions, the sensitivity of analytes was enhanced from 100‐ to 737‐fold as compared to normal CZE with hydrodynamic injection, giving LOD of 4.89, 5.29, and 53 μg/L for MP, NP and CP, respectively. The LODs were adequate for the analysis of NP and CP in environmental water sample having concentration at or lower than their maximum admissible concentration limit (240 and 2000 μg/L for NP and CP). The LOD of MP can be suitable for the analysis of MP exists at mid‐microgram per liter level, even though the LOD was slightly higher than the concentration usually found in water samples (from ng/L to 1 μg/L). The method repeatabilities (%RSD) were in the range of 1.07–2.39% (migration time) and 8.28–14.0% (peak area).     

Quartz crystal microbalance genosensor for sequence specific detection of attomolar DNA targets

A mass sensitive quartz crystal microbalance (QCM) based genosensor has been developed using breast cancer 1 (BRCA1) gene as a model gene. We modified the traditional sandwich assay by conjugating reporter probe DNA (DNA-r) with an assembly of gold nanoparticles leading to an increased mass on the surface, which enhanced the sensitivity to few orders of magnitude. The unique cleavage function of endonuclease is used for achieving the selectivity to complementary DNA over mismatched DNA. With this combination, the sensor exhibited excellent sensitivity with a detection limit of 10 aM BRCA1 gene and it showed good selectivity for even single base mismatch DNA targets. This ultrasensitive and cost-effective DNA detection protocol can be extended to the direct analysis of any non-amplified genomic DNA.     

Identification and Quantification of Hydrocarbon Functional Groups in Gasoline Using 1H-NMR Spectroscopy for Property Prediction

Gasoline is one of the most important distillate fuels obtained from crude refining; it is mainly used as an automotive fuel to propel spark-ignited (SI) engines. It is a complex hydrocarbon fuel that is known to possess several hundred individual molecules of varying sizes and chemical classes. These large numbers of individual molecules can be assembled into a finite set of molecular moieties or functional groups that can independently represent the chemical composition. Identification and quantification of groups enables the prediction of many fuel properties that otherwise may be difficult and expensive to measure experimentally. In the present work, high resolution ¹H nuclear magnetic resonance (NMR) spectroscopy, an advanced structure elucidation technique, was employed for the molecular characterization of a gasoline sample in order to analyze the functional groups. The chemical composition of the gasoline sample was then expressed using six hydrocarbon functional groups, as follows: paraffinic groups (CH, CH₂ and CH₃), naphthenic CH-CH₂ groups and aromatic C-CH groups. The obtained functional groups were then used to predict a number of fuel properties, including research octane number (RON), motor octane number (MON), derived cetane number (DCN), threshold sooting index (TSI) and yield sooting index (YSI).     

Andrographolide: A Herbal-Chemosynthetic Approach for Enhancing Immunity,Combating Viral Infections,and Its Implication on Human Health

Plants consistently synthesize and accumulate medically valuable secondary metabolites which can be isolated and clinically tested under in vitro conditions. An advancement with such important phytochemical production has been recognized and utilized as herbal drugs. Bioactive andrographolide (AGL; C₂₀H₃₀O₅) isolated from Andrographis paniculate (AP) (Kalmegh) is a diterpenoid lactones having multifunctional medicinal properties including anti-manic, anti-inflammatory, liver, and lung protective. AGL is known for its immunostimulant activity against a variety of microbial infections thereby, regulating classical and alternative macrophage activation, Ag-specific antibody production during immune disorder therapy. In vitro studies with AGL found it to be effective against multiple tumors, neuronal disorders, diabetes, pneumonia, fibrosis, and other diverse therapeutic misadventures. Generally, virus-based diseases like ZIKA, influenza A virus subtype (H1NI), Ebola (EBOV), Dengue (DENV), and coronavirus (COVID-19) epidemics have greatly increased scientific interest and demands to develop more effective and economical immunomodulating drugs with minimal side effects. Trials and in vitro pharmacological studies with AGL and medicinally beneficial herbs might contribute to benefit the human population without using chemical-based synthetic drugs. In this review, we have discussed the possible role of AGL as a promising herbal-chemo remedy during human diseases, viral infections and as an immunity booster.     

Schottky effect mechanism in poly(pyromellitic‐4,4‐diphenyl sulphone) films

An investigation was carried out to examine the conduction mechanism in poly(pyromellitic‐4,4‐diphenyl sulphone) [PPDS] films prepared by cast method. The electrical properties were measured in aluminum/polymer/aluminum structure over the temperature range (30–100 °C). At low field region, Ohm's law was obeyed whilst at fields high enough to cause injection of charge carriers, the electrodes supplied all the carriers and Schottky effect mechanism was observed as a prevail one. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2507–2514, 2000     

Synthesis and properties of a soluble and widely conjugated polyacetylene with anthryl pendant

The metathesis polymerization of an anthrylacetylene bearing an alkyl ester group, 9‐(10‐hexoxycarbonyl)anthrylacetylene ( 1 ), was conducted with various transition‐metal catalysts. A completely soluble black polymer was obtained from 1 in a good yield when W‐based catalysts were employed. The polymerization at a high monomer concentration (1 M) and a high temperature (80 °C) led to the formation of poly( 1 ) with a weight‐average molecular weight of 297 × 10³ in an 80% yield. The use of cocatalysts unexpectedly decreased both the yield and molecular weight of poly( 1 ). Rh‐catalyzed and Mo‐catalyzed polymerizations, however, resulted in poor yields of the polymer. The ultraviolet–visible spectrum of poly( 1 ) showed a significantly redshifted absorption (λ_max = 571) with a cutoff at 780 nm, which verified the very high order of conjugation of the main chain. Poly( 1 ) exhibited the largest third‐order nonlinear optical susceptibility [χ⁽³⁾ (−ω; ω, 0, 0) = − 1.9 × 10⁻¹⁰ esu] among the polymers from the monosubstituted polyacetylenes synthesized so far. The electrical conductivity of poly( 1 ) in an I₂‐doped state was 8.77 × 10⁻⁴ at 293 K. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4717–4723, 2000