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Abstract: Expanded calixpyrrole‐type macrocycles, calix[2]benzo[4]pyrroles, bearing fluorescent moieties attached via conjugated vinyl spacers, have been synthesized from the corresponding formyl derivatives through Knoevenagel condensation. The anion‐binding properties of the resulting fluorescent macrocycles have been studied by means of NMR, UV/Vis, and fluorescence spectroscopies. Our main focus has been on dicarboxylates matching the size of the binding cavity of the calix[2]benzo[4]pyrrole skeleton. The observed anion‐binding properties were compared with those of the regular calix[4]pyrroles bearing identical fluorophores. Surprisingly, the parent calix[4]pyrroles appear to be equally efficient, if not more so, for sensing anions such as dicarboxylates. Affinity constants determined for various anions and dianions show the sensors S1–S5 to be highly cross‐reactive. The cross‐reactivity of the sensors was utilized in a microchip‐based array, which showed perfect (100 %) classification of 18 analytes utilizing only five sensors. Finally, the same array was used to quantitatively analyze dicarboxylates such as oxalate and malonate. The data from the array were subjected to linear regression, allowing the determination of various concentrations of dianions with low error (<2 %). [ABSTRACT FROM AUTHOR]

A highly accurate and reliable screening method for enantiomeric excess of amine derivatives in the presence of water is reported. The fluorescence-based screening system has been realized by self-assembly of chiral diol-type dyes (BINOL, VANOL and VAPOL), 2-formylphenylboronic acid, and chiral amines forming iminoboronate esters. The structure and chirality of the amine analytes determine the stability of the diastereomeric iminoboronate esters, which in turn display differential fluorescence. The fluorescence signal reflects the enantiomeric purity of the chiral amines and was utilized in high-throughput arrays. The arrays were able to recognize enantiomeric excess of amines, amino esters, and amino alcohols. In addition to qualitative analysis, quantitative experiments were successfully performed. Studies of the role of additives such as water or citrate were carried out to gain insight into the stability of the iminoboronate esters. It is shown that the above additives destabilize less stable esters while the stable esters remain unchanged. Thus, the presence of water and citrate leads to increased difference between the diastereomeric iminoboronates and contributes to the enantiodiscrimination of the chiral amines. [ABSTRACT FROM AUTHOR]

Methods allowing chemical reactions to be carried out on ultra-small scales in a controllable fashion are potentially important for a number of disciplines, including molecular electronics, photonics and molecular biology, and may provide fundamental insight into chemistry in confined spaces. Ultra-small-scale reactions also circumvent potential problems associated with reagent and product toxicity, and reduce energy consumption and waste generation. Here, we report a technique for performing chemical reactions on a zeptomole (10−21 mol) scale. We show that electrospun polymer nanofibres with a diameter of 100–300 nm can be loaded with reactants, and that the junctions formed between crossed nanofibres can function as attolitre-volume reactors. Exposure to heat or solvent vapours fuses the fibres and initiates the reaction. The reaction products can be analysed directly within the nanofibre junctions by fluorescence measurements and mass spectrometry, and solvent extraction of multiple reactors allows product identification by common micromethods such as high-performance liquid chromatography–mass spectrometry. [ABSTRACT FROM AUTHOR]

Octamethylcalix[4]pyrrole derivatives with hydroxy alkyl and amino alkyl side chains were prepared and converted into the corresponding acrylate and acrylamide derivatives, respectively. [ABSTRACT FROM AUTHOR]

Reports on the synthesis of monosubstituted calix[4]pyrrole derivatives containing acid, ester, iodo and formyl as well as calix[4]-pyrrole-2-ethanol species. Synthetic procedure; Effect of electrophile equivalent employed on isolated yield of monosubstituted calix[4]pyrrole derivatives; Structural characteristics of the derivatives.

Explores the use of 3,4-difluoro-1H-pyrrole as a building block for the preparation of octamethyloctafluorocalix[4]pyrrole and 2,3-di(3',4'-difluoropyrrol-2'yl)quinoxaline. Mechanism of the receptors; Affinity for dihydrogen phosphate; Presence of several macrocylic conformations in octofluorocalix[4]pyrrole system.

Amino acids and their derivatives are recognized and analyzed in water using a turn-on fluorescent cucurbituril based sensor array. Multivariate analysis (LDA and HCA) clearly shows that the sensor array can discriminate amino acids from the corresponding amines which are produced by the action of amino acid decarboxylases. [ABSTRACT FROM AUTHOR]

The halide anions are essential for supporting life. Therefore, halide anion analyses are of paramount importance. For this reason, we have performed both qualitative and quantitative ana- lyses of halides (chloride, bromide, iodide) using the Tl(III) complex of azodye, 4-(2-pyridylazo)re- sorcinol (PAR), a potential new chemical reagent/sensor that utilizes the substitution reaction whereas the Tl(III)PAR complex reacts with a halide to yield a more stable thallium(III)-halide while releasing the PAR ligand in a process accompanied by color change of the solution. The experimental conditions (e.g., pH, ratio metal ion-to-ligand ratio, etc.) for the substitution reaction between the metal complex and a halide were optimized to achieve increased sensitivity and a lower limit of detection (chloride 7 mM, bromide 0.15 mM, iodide 0.05 mM). It is demonstrated that this single chemosensor can, due to release of colored PAR ligand and the associated analyte-specific changes in the UV/VIS spectra, be employed for a multicomponent analysis of mixtures of anions (chloride + bromide, chloride + iodide, bromide + iodide). The spectrophotometric data evaluated by artificial neural networks (ANNs) enable distinguishing among the halides and to determine halide species concentrations in a mixture. The Tl(III)-PAR complex was also used to construct sensor arrays utilizing a standard 96-well plate format where the output was recorded at several wavelengths (up to 7) using a conventional plate reader. It is shown that the data obtained using a digital scanner employing only three different input channels may also be successfully used for a subsequent ANN analysis. The results of all approaches utilized for data evaluation were similar. To increase the practical utility of the chemosensor, we have developed a test paper strip indicator useful for routine naked-eye visual determination of halides. This test can also be used for halide anion determination in solutions using densitometer. The methodology described in this paper can be used for a simple, inexpensive, and fast routine analysis both in a laboratory as well as in a field setting. [ABSTRACT FROM AUTHOR]

The charge injection properties of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate anodes are crucial for performance of organic photovoltaics and organic light-emitting diodes (OLEDs). A simple method for tuning hole injection efficiency using UV-ozone is shown to change anode work-function and optimized carriers balance in the devices and improved efficiency in OLEDs. The optimum time of treatment and work-function differs with device architecture. [ABSTRACT FROM AUTHOR]

The treatment of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films by ultraviolet (UV) light-ozone to improve device efficiency was investigated utilizing two simple phosphorescent organic light-emitting diodes (PHOLEDs) architectures. The maximum external quantum efficiency in the first device increased from 3.5% for the untreated anode to 10.5%, while in the second device comprising an exciton blocking layer increased from 15.8% to 18.5%. The time dependence of the UV-ozone treatment on the performance was studied. The dramatic improvement in the PHOLED performance is attributed to the change in the PEDOT:PSS work function and more balanced charge injection, suggesting promising easy-to-do method to improve PHOLED performance. [ABSTRACT FROM AUTHOR]

White light with good color properties (color rendering index=82–87) is generated in a simple organic light-emitting diode comprising an emissive layer, composed of an undoped tris(4-methyl-8-quinolinato)aluminum (Almq3) sublayer and region doped with an orange-red phosphorescent dopant, bis(2-phenyl-1-quinoline)iridium acetylacetonate (Ir(pq)2acac). Electron-hole recombination in a thin spacing Almq3 layer results in blue-green fluorescence, while the formed triplet excitons diffuse to the doped region and are harvested by the dopant to emit orange-red phosphorescence. The combination of blue-green and orange lights results in warm white light. This approach takes advantage of efficient migration of triplet excitons while being less demanding in terms of fabrication and color matching. [ABSTRACT FROM AUTHOR]

The article discusses sensing of antipyretic carboxylates by simple chromogenic Calix[4]pyrroles. Octamethylcalix[4]pyrrole (OMCP), an easy-to-make, colorless macrocycle containing four pyrrole NHs as hydrogen bond donors is an ideal candidate for the preparation of optical anion sensors. Indeed, several OMCP derivatives displaying anion-induced changes in either color or fluorescence have been synthesized by attaching pre-existing chromophores to the OMCP. Unfortunately, this approach proved too costly, and together with the fact that these materials could not be used in aqueous environments, precluded their application as anion sensors.

Accurate determination of levels of phosphate-related anions such as pyrophosphate and nucleotide phosphates is an important factor in monitoring numerous metabolic processes. Very few sensors exist that display high selectivity and reliability and that function in aqueous media without interference from endogenous substrates such as chloride anion. That is because selective and reliable sensing of anions is generally difficult to accomplish. As compared to isoelectric cations, anions often display a high energy of hydration, display tautomerism, and possess low surface-charge density.

Examines the use of luminescence lifetime-based sensor for cyanide and related anions. Identification of the metal-to-ligand charge transfer states of ruthenium diimine compounds; Utilization of chromophore-displacement method for the optical sensing of anions; Occurrence of cyanide titration.

A preface for the January-March 2009 issue of the journal "Supramolecular Chemistry" is presented.