Toward Soluble 5,10-Diheterotruxenes: Synthesis and Reactivity of 5,10-Dioxatruxenes, 5,10-Dithiatruxenes, and 5,10-Diazatruxenes.

The following work presents three general approaches allowing, for the first time, the synthesis of 5,10-diheterotruxene derivatives containing two identical heteroatoms, namely, oxygen OOC, nitrogen NNC, or sulfur SSC. Two of described pathways involve the photocyclization of the corresponding triene 2 as a key step leading to a heptacyclic aromatic system. The third approach is based on the acidic condensation between ninhydrin 14 and benzo[b]heteroole 15. Typical functionalizations of the 5,10-diheterotruxene core have also been presented. In addition, the article discusses the advantages and limitations of the three suggested paths for receiving specific 5,10-diheterotruxene derivatives because the universal method suitable for obtaining molecules with any type of heteroatoms is not known so far.

Synthesis and Reactivity of 5-Heterotruxenes Containing Sulfur or Nitrogen as the Heteroatom.

This paper presents an alternative path for the synthesis of 5-thiatruxene and the synthetic approach for 5-azatruxene not known so far. A new method for 5-thiatruxene improves the overall reaction yield from 17.5 to 22.6%, diminishes the synthesis time and costs by reducing synthetic steps from 5 to 2, and simplifies the isolation of intermediate and final products. The overall reaction yield for 5-azatruxene is 32.4%. The typical reactivity of both aromatic systems is also demonstrated. Recent research results suggest the use of 5-thiatruxene as the acceptor subunit of soluble blue emitters.

Aggregation-Induced Emission of EuIII Complexes Balanced with Bulky and Amphiphilic Imidazolium Cations in Ethanol/Water Binary Mixtures.

A series of EuIII complexes with thenoyltrifluoroacetone (tta) as the ligands were synthesized, which are balanced with imidazolium cations bearing naphthyl and branched alkyl chains. The complex with the longest alkyl chain (1Eu(tta)4 ) shows aggregation behavior in ethanol and water mixtures. It exists as individuals at low water percentages (VH2O ), and form particles with solid interiors at VH2O ≥50 % the sizes of which decrease with the increase of VH2O . At VH2O =90 %, vesicles were observed. The aggregation of 1Eu(tta)4 in ethanol and water binary mixtures induced changes of the photoluminescence (PL) properties where an abrupt increase in PL intensity, quantum yield, and lifetime were noticed above VH2O =50 %. This PL enhancement can be explained by the encapsulation of 1Eu(tta)4 inside the aggregates, preventing it from quenching by the active hydroxyls of water molecules. Contrary to the aggregation-induced emission (AIE) of the Eu complex, the naphthyl group in the imidazolium cation exhibited an aggregation-caused quenching (ACQ) effect. When the length of the alkyl chain in the imidazolium cation is reduced, no PL enhancement can be observed owing to the difficulty in forming the aggregates.

Luminescent studies of binuclear ternary europium(III) pyridineoxide tetrazolate complexes containing bis-phosphine oxide as auxiliary co-ligands.

A new class of antenna chromophores so called 'tetrazolates' have not been explored much for lanthanide luminescencent complexes. However, we have already published several articles considering pyridineoxide tetrazolates as sensitizer with lanthanide ions. Although this class of antenna attracted much less attention because of its poor photoluminescence quantum yields (tris-pyridineoxide tetrazolate europium complex = 13% in solution) we tried and successfully achieved to improve the photoluminescence quantum yields for this particular antenna molecule by replacing coordinated water from the inner coordination sphere of europium ion by introducing phosphine oxides as additional chromophore. In the present article the two bis-phosphine oxides attach two molecules of tris-pyridineoxide tetrazolate europium(III) complex which leads to the improvement of the overall molar absorption coefficients as well as photo-physical properties of the complexes. We found more than two-fold increase (31% in solution) in photoluminescence quantum yield with one of the coordinated phosphine oxides comparing with that of tris-pyridineoxide tetrazolate europium(III) complex.

Synthesis and photophysical studies of tetrazolate-based Eu(III) photoluminescent ternary complexes containing N-heterocyclic phosphine oxides auxiliary co-ligands.

Two new ternary tetrazolate Eu(III) complexes with phosphine oxide co-ligands Eu(PTO)3 ·(P1/P2) [PTO = 5-(2-pyridyl-1-oxide)tetrazole, P1 = diphenylphosphorylamino-phenylphosphoryl-benzene, P2 = diphenylphosphorylpyridine)-bis-isobutyricphosphoryl] were synthesized and characterized using UV, fluorescence, IR and (1) H NMR spectroscopic techniques. The analytical data prove that the complexes are mononuclear in nature and the central Eu(III) ion is coordinated by three N and three O atoms of tetrazolate, and two O atoms of the corresponding bidentate phosphine oxide ligands. The ancillary ligand increased the photoluminescence efficiency of Eu(PTO)3 ·P1 (complex 3) by twofold compared with our previously reported Eu(PTO)3 complex (complex 1). Copyright © 2015 John Wiley & Sons, Ltd.

Fullerene-driven encapsulation of a luminescent Eu(III) complex in carbon nanotubes.

A novel CNT-based hybrid luminescent material was obtained via encapsulation of a C60-based Eu(III) complex into single-, double- and multi-walled carbon nanotubes (SWCNTs, DWCNTs and MWCNTs, respectively). Specifically, a luminescent negatively charged Eu(III) complex, electrostatically bonded to an imidazolium-functionalized fullerene cage, was transported inside CNTs by exploiting the affinity of fullerenes for the inner surface of these carbonaceous containers. The filling was performed under supercritical CO2 (scCO2) conditions to facilitate the entrapment of the ion-paired assembly. Accurate elemental, spectroscopic and morphological characterization not only demonstrated the efficiency of the filling strategy, but also the occurrence of nano-ordering of the encapsulated supramolecular luminophores when SWCNTs were employed.

Electrostatically-driven assembly of MWCNTs with a europium complex.

Luminescent carbon-based materials have been prepared by electrostatic self-assembly of negatively-charged luminescent Eu(III)-complex with imidazolium-functionalized MWCNTs.

Response of DNA fragments to potentiometric sensors studied using HPLC.

Potentiometric sensors are studied as viable candidates for the construction of high throughput DNA arrays. For preliminary investigations, such sensors were used in an HPLC setup in the present work. This avoided errors due to ionic contaminants or additives in the commercial samples. The oligonucleotides dT(10), dT(20) and dT(30) were used as test substances. The potentiometric sensors were of the coated wire type, containing PVC, DOP, MTDDACl and a synthetic podand urea receptor. The HPLC system consisted of a reversed phase column eluted with a phosphate buffer, triethylammoniumacetate (TEAA), and an acetonitrile gradient. Molar responses and sensitivities increased with increasing chain length of oligonucleotides, yielding detection limits as low as 10(-6)M (dT(30), injected concentration). The slopes of the calibration graphs were at least 23 mV/decade (dT(10)), which was much higher than expected. The results are discussed in view of the potential use of this sensor type in high throughput microarrays.

Coated wire potentiometric detection for capillary electrophoresis studied using organic amines, drugs, and biogenic amines.

Capillary electrophoresis was coupled successfully and reliably to potentiometric sensors, which are based on an ionically conductive rubber phase coating, applied on a 250 microm diameter metal substrate. The membrane components included potassium tetrakis(p-chlorophenyl)borate (TCPB), bis(2-ethylhexyl)sebacate (DOS), and high molecular mass poly(vinyl chloride) (PVC). Potentiometry reveals a very sensitive CE detection mode, with sub-micromolar detection limits for amines and the randomly chosen drugs quinine, clozapine, cocaine, heroine, noscapine, papaverine, and ritodrine. The lowest detection limit, 1 x 10(-8) M injected concentration, was obtained for the quaternary ammonium compound tetrahexylammonium chloride. The more polar lower aliphatic amines and the biogenic amines dopamine, adrenaline, and cadaverine have much higher detection limits. The detection limits are log P dependent. Addition of a commercially available calixarene molecule or a synthetic macrocyclic amphiphilic receptor molecule to the electrode coatings enhanced the sensitivity respectively for the lower aliphatic amines and for the biogenic amines. A transpose of the Nikolskii-Eisenman-type function was suggested and used to convert the signal of the detector to a concentration-dependent signal.