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We report six new 2,6-disubstituted fluorene-based conjugated molecules carrying orthogonal triphenylamine and pyridine moiety as donor-acceptor units at the C-9 position. The geminal donor-acceptor is connected to the fluorene core by σ-conjugation. Optical/solvatochromic studies, investigated by UV-VIS absorption and fluorescence spectroscopy, show blue emission with good quantum yield (40–70%) in solution and in thin film state for the synthesized compounds. In microsecond order, the derivatives give a shorter delayed lifetime (both in solution and thin films), facilitating reverse intersystem crossing (RISC). TD-DFT studies for all the derivatives show minimal singlet-triplet splitting in the gas phase (close to 0.2 eV), and the high thermal stability confirmed by the compound's TGA method (320–398 °C) makes them very useful in the optoelectronic market. D-σ-π-σ-A based blue emitters carrying orthogonal triphenylamine and pyridine moiety as donor-acceptor unit at C-9 position were synthesized. Optical/solvatochromic studies, investigated by UV-VIS absorption and fluorescence spectroscopy, show blue emission with good quantum yield (40–70%) in solution and in thin film state for the synthesized compounds. [ABSTRACT FROM AUTHOR]

Three new hexaphenylbenzene end-capped tri( p -phenylenevinylenes) were synthesized by the Horner–Wadsworth–Emmons reaction in good yields (86–76%). All compounds have bright fluorescent emissions in the blue to blue–green region in solution ( λ max = 445–492 nm in tetrahydrofuran) and also high emission efficiency ( Φ fl = 0.51–0.72 in tetrahydrofuran). They exhibit good electrochemical reversibility, high thermal stability, and have high HOMO value. [ABSTRACT FROM AUTHOR]

Abstract: Three new tetraphenylethylene based oligomers bearing triphenylethylene moiety were synthesized utilizing Suzuki coupling reaction and their aggregation-induced emission properties were studied. They show excellent solubility in common organic solvents and emit light in blue region (440−504nm). AIE effect is predominant for tetra-substituted TPE (20.1-fold) than mono-substituted one (4.5-fold). [Copyright &y& Elsevier]

Abstract: A new series of V-shaped pyridine-cored π-conjugated oligomers are synthesized utilizing two-fold Heck/Suzuki coupling reactions. Optical properties of these compounds (λ max=390–449 nm, Φ fl=79–5%, in solutions) are discussed. They are shown to be thermally stable and soluble in common organic solvents. Stilbenoid oligomers exhibited much higher fluorescence quantum yields than tri- and tetra-phenylethylene substituted oligomers in solutions. [Copyright &y& Elsevier]

Abstract: Two novel star-shaped π-conjugated oligomers bearing a triphenylpyridine moiety as peripheral units and triphenylamine as a core have been synthesized via the threefold Heck/Sonogoshira coupling reaction protocol and their absorption and fluorescence properties have been examined. These oligomers showed excellent solubility in common organic solvents, emit light in blue and violet regions, and have high thermal stability. [Copyright &y& Elsevier]

Abstract: A new regioselective one-pot procedure to synthesize pyranoquinolinones from readily available 2-alkynyl 3-formylquinolines under mild NaClO2/H2O2 conditions in good yields has been explored. This reaction sequence, involving oxidation followed by regioselective electrophilic 6-endo-dig cyclization is more efficient over the traditional Pd(0)-mediated synthesis. When scavenger-free conditions were used, unusual chlorinated furoquinolinone derivatives were obtained. [Copyright &y& Elsevier]

Abstract: Two new conjugated dendrimers bearing a tetraphenylethylene moiety as dendrons and triphenylamine as a core have been synthesized through a convergent synthetic strategy using threefold Heck/threefold Sonogashira coupling reaction. These dendrimers showed excellent solubility in common organic solvents and emit light in the blue and violet regions. [Copyright &y& Elsevier]

Abstract: One-pot three-component coupling of o-alkynylheteroaryl carbonyl derivatives with α,β-unsaturated Fischer carbene complexes and dimethyl acetylenedicarboxylate leading to the synthesis of heterocyclic analogues of furanophane derivatives has been explored. This involves the generation of conformationally flexible dienylazaisobenzofuran intermediate as transient intermediates, which undergo [8+2] cycloaddition reaction with dienophile. In some cases, this intermediate undergoes twofold Diels–Alder reaction to afford heterolignan derivatives in a single step. [Copyright &y& Elsevier]

Abstract: The coupling of Fischer carbene complexes with 2-alkynyl-3-pyridine carbonyl derivatives has been examined. The reaction affords furo[3,4-b]pyridine as transient intermediates; the latter undergo [4+2] cycloaddition with an electron-deficient dienophile. Acid/base-induced ring opening of the exo-cycloadducts followed by aromatization give substituted quinolines related to heterocyclic analogues of 1-arylnaphthalene lignans. An intramolecular variant of this protocol is also feasible with use of unactivated alkenyl tethers; however, the bridged cycloadducts are unisolable as they undergo spontaneous ring opening to yield alcohol. This method is also useful for the in situ generation of the furo[3,4-b]quinoline intermediate for the first time, which can be trapped with dienophiles. [Copyright &y& Elsevier]

Discusses the usage of the thermal and lewis acid-catalyzed intramolecular alder ene reaction. Indication of results of reaction; Relationship between the stereochemistries of substituents on the tether and the stereochemistry of C,C bond formation; Exploration of the intramolecular ene reactions for organic synthesis.

Abstract: A new route for the synthesis of furo[2,3-h]quinoline and furo[2,3-h]isoquinoline derivatives have been explored through the coupling of carbene complexes with pyridine-bridged enynes. This reaction process, involving the annulation of both furan and benzene ring on to a pre-existing pyridine ring is highly efficient in the presence of triphenylphosphine as ligand additive. [ABSTRACT FROM AUTHOR]

Chitosan-based polymers are commonly used as drug delivery carriers and for functional modification of nanoparticle/polymers. Herein, we report a functional chitosan oligosaccharide with a self-assembly-induced fluorescence ‘switch on’ property, and that also exhibits a similar type fluorescence ‘off’ to ‘on’ state via subcellular localization. Specifically, chitosan oligosaccharide was conjugated with aggregation induced emission (AIE) active tetraphenylethene (TPE) and lipophilic–cationic triphenylphosphonium (TPP) molecules. The resultant functional chitosan self-assembles into 50–200 nm particles, whereby TPE offers a self-assembly induced fluorescence ‘switch on’ property and TPP offers cell uptake via lipophilic–cationic surface properties. The self-assembled chitosan nanoparticle enters into the cell predominately by lipid-raft endocytosis and exhibit a fluorescence ‘off’ to ‘on’ state upon localization at the lysozome. We have shown that adjustment of the number of TPP/TPE molecules bound to each chitosan is critical for the self-assembly induced fluorescence ‘switch on’ property and the subcellular localization-dependent fluorescence ‘off’ to ‘on’ state performance. Other fluorescence ‘switch on’ type sub-cellular imaging probe could be designed with appropriate functional modification of chitosan oligosaccharide or similar macromolecules. [ABSTRACT FROM AUTHOR]

Abstract: Four new gem-tetraphenylethylene-based oligomers were synthesized by Suzuki coupling reaction in good yields (62–80%) and characterized by NMR, mass spectrometer and elemental analysis. The absorption maxima of the synthesized oligomers in the solution possess similar absorption bands located at 328–332 nm. They are shown to be thermally stable and emit light in blue region (404–485 nm). All the oligomers are AIE-active, emit weakly in solutions with Φ f values not exceeding 4%, become strong emitters in the aggregated states and the PL intensity values increase up to 18-fold. The results of CV measurements of the oligomers showed good reversibility, indicating that the compounds have good electrochemical stability. The HOMO values of the oligomers are in the range of −5.63 to −5.61 eV. The photoluminescence properties in aggregate-state and the high HOMO energy levels of these oligomers make them applicable as an active material for a light-emitting device. [Copyright &y& Elsevier]

One-pot, three-component synthesis of nitrogen-containing polycyclic heterocycles bearing two nitrogen atoms such as quinoxaline, quinazoline, and phenazine derivatives by the coupling of appropriate vicinal alkynylheteroaryl carbonyl derivatives with Fischer carbene complexes and dienophiles has been investigated. This involves the generation of furo[3,4-b]pyrazines, furo[3,4- d]pyrimidines, and furo[3,4-b]quinoxalines as transient intermediates, which were trapped with suitable Diels-Alder dienophiles in an inter- or intramolecular fashion. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of Fischer carbene complex with o-alkynylpyridine carbonyl derivatives has been investigated. This involves the generation of furo[3,4-c]pyridine as transient intermediates through the coupling of o-alkynylpyridine carbonyl derivatives with carbene complex and subsequent Diels–Alder trapping with suitable dienophiles resulted in the formation of isoquinoline derivatives and the entire sequence can be run in one pot. When an olefinic tether was present, intramolecular Diels–Alder cycloaddition occurred followed by ring opening to yield tricyclic alcohols. [Copyright &y& Elsevier]

Aggregation behavior of luminophores is a subject of great interest over more than half a century. Aggregation generally causes quenching of luminescence of luminophores, which is detrimental for the solid state electroluminescence device fabrication. In oppose to the aggregation caused quenching, aggregation-induced emission phenomenon leads to highly luminescence state of luminophores upon aggregate formation. However, aggregation-induced emission behavior of the luminophores is commonly observed in irregular bulk solids, by adding antisolvents into a solution or in the biological cells, where the state of aggregation remains uncontrolled. Here we report on the synthesis of a new tailor made luminogen, 4′,4‴-(2,2-bis(4-methoxyphenyl)ethene-1,1-diyl)bis([1,1′-biphenyl]-4-carbaldehyde) (TPE 2) using Suzuki coupling reaction with high yield. We form the well-controlled supramolecular aggregates of TPE 2 ​at the air−water interface of a Langmuir trough. As a consequence, the mono- and multilayer Langmuir−Blodgett films of TPE 2 show a large enhancement of luminescence in comparison to the solution phase owing to the aggregation-induced emission phenomenon. We reveal inherent interaction of TPE 2 complexes within the supramolecular aggregates using density functional theory. This unique feature of luminescence enhancement is utilized for the fabrication of light-emitting diodes with low threshold voltage using TPE 2 as active layer. This study opens up the advantage of ordered supramolecular assembly to achieve optimal luminescence performances. A new tailor made AIE luminogen, TPE 2 , form well-controlled supramolecular spherical aggregates at the air−water interface of a Langmuir trough. Fabrication of light emitting diodes using supramolecular aggregates as active layer is demonstrated. Image 1 • Supramolecular aggregates at the air-water interface. • Langmuir-Blodgett organized assembly. • Aggregation induced emission. • Light emitting diode fabrication. [ABSTRACT FROM AUTHOR]