Optical supermicrosensor responses for simple recognition and sensitive removal of Cu (II) Ion target

The field of optical chemosensor technology demands a simple yet general design for fast, sensitive, selective, inexpensive, and specific recognition of a broad range of toxic metal ions. The suitable accommodation of chromogenic receptors onto ordered porous carriers have led to selective and sensitive chemosensors of target species. In this study, we offer real evidence on the potential use of two- and three-dimensional (2D and 3D) ordered supermicroporous monoliths as selective shape and size carriers for immobilizing the chromogenic probe. Among all the chemosensors, 3D supermicropore has exhibited easy accessibility of target ions, such as ion transports and high affinity responses of receptor-metal analyte binding events. This leads to an optical color signal that is easily generated and transduced even at trace levels of Cu(II) target ions. The supermicrosensors have shown the ability to create Cu(II) ion-sensing responses up to nanomolar concentrations (∼10⁻⁹ mol/dm³) with rapid response time (in the order of seconds). Supermicrosensors have the ability to create easily modified sensing systems with multiple regeneration/reuse cycles of sensing systems of Cu(II) analytes. The simple treatment using ClO₄⁻ anion as a stripping agent has removed effectively the Cu(II) ions and formed a “metal-free” probe surface. The supermicrosensors have exhibited the specificity behavior permitting Cu(II) ion-selective determination in real-life samples, such as in wastewater, despite the presence of active component species. Extensive analytical results indicate that the use of the supermicrosensor as Cu(II) ion strips for field screening can be a time- and cost-alternative tool to current effective laboratory assays.     

Pictet‐spengler synthesis of pyrazole‐fused β‐carbolines

The synthesis of new pyrazolo[4,3‐c]β‐carbolines ( 8a,b ) is achieved by condensation of the appropriate aldehyde with 3‐(4‐amino‐1,3‐dimethylpyrazol‐5‐yl)indole ( 4 ) under Pictet‐Spengler reaction conditions. Regioselective cyclization occurred at the usual indole C‐2 position as evidenced from the ¹H‐and ¹³C nmr spectra of 8a,b which lack the pyrrolic H‐2 signal, present in 4 (δ 7.26, 1H, d, J_ch‐NH = 2‐5 Hz).     

Use of doubly protonated molecules in the analysis of cathedulins in crude extracts of khat (Catha edulis) by liquid chromatography/serial mass spectrometry

Analysis of crude methanolic extracts of fresh khat (Catha edulis) by liquid chromatography/mass spectrometry (LC/MS) revealed the presence of 62 cathedulin alkaloids (compared with 15 published structures). Many cathedulins generated doubly protonated molecules following electrospray ionisation and the ratio of doubly to singly protonated species could be manipulated by adjusting the electrospray capillary position and source conditions. By selecting the doubly protonated species for serial mass spectrometric analysis (MS/MS), it was possible to use an ion trap mass spectrometer to observe singly charged product ions at lower m/z values than ion trap MS/MS analysis of [M+H](+) would have allowed. These spectra were particularly valuable in elucidating the acylation patterns of cathedulins where MS/MS analysis of [M+H](+) resulted in loss of a large neutral species to yield a small singly charged fragment below the lower limit for ion trapping. Acylation patterns for most of the 62 cathedulins are proposed from mass spectrometric analysis, and the data obtained for a major unreported cathedulin of mass 1001 Da suggest that it belongs to a new group of cathedulins having a cathate dilactone bridge but not an evoninate bridge.     

N-1-Naphthyl-3-oxobutanamide in Heterocyclic Synthesis: A Facile Synthesis of Nicotinamide,Thieno[2,3-b]pyridine,and Bi- or Tricyclic Annulated Pyridine Derivatives Containing Naphthyl Moiety

N-1-Naphthyl-3-oxobutanamide (1) reacts with arylidinecyanothioacetamide 2a–c in ethanol/piperidine solution under reflux to yield the pyridine-2(1H)-thiones 6a–c. Compound 6a reacts with α-haloketones 7a–e to give the 6-thio-N-1-naphthyl-nicotinamides derivatives 8a–e, which cyclized to thieno[2,3-b]pyridine derivatives 9a–e. The reaction of compound 9a with hydrazine hydrate and formamide gives the thieno[2,3-b]pyridine carbohydrazide derivative 10 and pyridothienopyrimidine derivative 11, respectively. Reaction of 9a with benzoyl isothiocyanate gave thiourea derivative 12. Compound 12, upon treatment with alcoholic NaOH, gave pyridothienopyrimidine 13. Saponifications of 9a gave the amino acid 15, which affords 16 when refluxed in Ac₂O. Treatment of compound 16 with AcONH₄/AcOH gave 17. Diazotization and self-coupling of 9b gave the pyridothienotriazine 18. Also, diazotization of the ortho-aminohydrazide 10 give the corresponding azide 19, which was subjected to Curtius rearrangement in boiling xylene to give imidazothienopyridine 20. Reaction of 10 with either formic acid or triethylorthoformate and phenyl isothiocyanate gave the corresponding pyridothienotriazepines 22 and 23, respectively. The interaction of 10 with acetylacetone furnished the pyrazolyl derivative 24. The structures of the synthesized compounds were established from their analytical and spectral data.     

Isolation and characterization of triterpenes from the leaves of Orthosiphon stamineus

Orthosiphon stamineus, Benth, belonging to the family Lamiaceae, is a medicinal plant growing wild in tropical countries. Seven triterpenes, ursolic acid, oleanolic acid, betulinic acid, hydroxybetulinic acid, maslinic acid, α-amyrin and β-amyrin have been isolated from the leaves of Orthosiphon stamineus. The structures of these compounds have been established by spectroscopic methods. α-Amyrin was isolated from this plant for the first time.     

MOLECULAR REARRANGEMENTS. VI. THERMOLYSIS OF α-(N-ARYL)BENZYL ARYL SULFIDES

Abstract

In view of the significance of studying the effect of heat on organic compounds especially those containing nitrogen and/or sulfur, six substituted α-(N-aryl) benzyl aryl sulfides (4–9) were prepared and subjected to thermolysis at 200°C.

Surveying of the reaction products showed the formation of amines, benzylidene amines, sulfides, disulfides, dibenzyl, stilbene, benzthiazole, benzimidazole, tetraphenyl thiophene as principle products in variable ratios according to the type of the starting sulfide.

A mechanism involving the homolytic cleavage of the C[sbnd]S and the C[sbnd]N bond is suggested to rationalize the thermolysis products.     

Micellization and Adsorption Parameters of Poly(Propylene Oxide)/Poly(Ethylene Glycol) Block and Graft Copolymers in Aqueous Medium

This work aims to measure the adsorption and micellization parameters of new water soluble nonionic amphiphilic block and graft copolymers based on hydrophilic poly (ethylene glycol) (PEG) and hydrophobic poly (propylene oxide) (PPO) at ambient temperature and normal atmospheric pressure. The chemical composition and molecular weights of the prepared copolymers were determined from ¹H NMR analyses. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration, and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration, the area per molecule at interface and the effectiveness of surface tension reduction were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption and micellization process were calculated and are discussed.     

Palladium complexes bearing the dipyridyl ligand: synthesis,structural studies,and use in the Heck reaction

Two new palladium complexes derived from the di(2-pyridinyl)methanone N-(2-pyridinyl)hydrazone (DPMNPH) ligand are reported. The compounds were characterized by elemental analysis, spectroscopic studies, and, for the DPMNPH ligand, single-crystal X-ray diffraction analysis. The DPMNPH ligand crystallized as orthorhombic with the space group P2₁2₁2₁. The H1 atom is intramolecularly bonded to the pyridinic N4 with N1–H1 = 0.92(3) Å, H1···N4 = 1.87(2) Å, N1···N4 = 2.615(2) Å, and N1–H1···N4 = 137(2)°. Both complexes were excellent catalysts in the Heck reaction in the presence of base.