Synthesis, electropolymerization and functionalization via click chemistry of N-alkynylated dithieno[3,2-b:2',3'-d]pyrrole

A new N-alkynylated dithieno[3,2-b:2′,3′-d]pyrrole (DTP) monomer was synthesized using a Buchwald–Hartwig amination of 3,3′-dibromo-2,2′-bithiophene with pent-4-yn-1-amine. The obtained monomer was investigated for the possibility of a pre-polymerization modification via Huisgen 1,3-dipolar cycloaddition (“click”) reaction with azide-containing organic compounds. The synthesized N-alkynylated DTP monomer is soluble in a number of organic solvents and reacts with organic azides via “click” reactions in mild conditions, achieving high yields. The N-alkynylated DTP monomer and its “click”-modified derivative can be electropolymerized to form polymeric films. Herein, the synthesis and characterization of a “click” modified DTP monomer, its pre-modified derivative, and their corresponding polymers are described. The developed method is a facile route to synthesize a new generation of various N-functionalized DTP homopolymers.

An N-alkynylated DTP monomer is functionalized with “click” reactions and provides a facile route to synthesize various N-functionalized DTP homopolymers.

Functionalized Quinoxaline for Chromogenic and Fluorogenic Anion Sensing

This Review article provides a comprehensive analysis of recent examples reported in the field of quinoxaline-based chromogenic and fluorogenic chemosensors for inorganic anions such as fluoride, cyanide, acetate, and phosphate, as well as their utility in biomolecular science. It commences with a discussion of the various structural motifs such as quinoxaline-based oligopyrroles, polymers, sulfonamides, cationic receptors, and miscellaneous receptors bearing mixed recognition sites in the same receptor. Advances are discussed in depth, where the focus of this review is to tackle mainly solution state anion sensing utilizing quinoxaline-based receptors using different spectroscopic techniques with reference to anion selectivity by colorimetric and fluorescence response. The various examples discussed in this Review illustrate how the integration of anion binding elements with the quinoxaline chromophore could result in anion responsive chemosensors. Over the years, it has been observed that structural modification of the quinoxaline moiety with different sets of signaling unit and recognition sites has resulted in a few anion specific chemosensors.

Tunable AIEE fluorescence constructed from a triphenylamine luminogen containing quinoline - application in a reversible and tunable pH sensor

Herein, tunable emissions in aggregation processes of triphenylamine derivatives (TPAQs) and their protonated cations, as well as protonated processes have been described. In this study, three triphenylamine-based compounds (TPAQs) were synthesized and their optical properties were investigated. Initially, the TPAQs displayed aggregation-induced emission enhancement (AIEE) properties via the restricted intramolecular charge transfer (ICT) state. Interestingly, the single-branched fluorophore (STPAQ) and its protonated cation emitted different color fluorescence in the solution and aggregation state. They emitted green fluorescence, which originated from the intramolecular charge transfer (ICT) state in a strong polar solvent, but the fluorescence bands turned blue, which was attributed to the LE state in the aggregated state. However, the cations of triple-branched fluorophores (TTPAQs) exhibited an inverse tunable emission process from bluish violet fluorescence of the LE state in a weak polar solvent (e.g., THF) to green fluorescence of the ICT state in the aggregated state. In a THF/water mixture solution (f_w = 10%), the STPAQ could switch its emission between blue and green in the pH range of 10.0-0.5. This phenomenon enabled STPAQ to serve as a fluorescent pH sensor in solution. In the powder state, double-branched fluorophores (DTPAQs) could be used as a fluorescent sensor for the detection of acidic and basic organic vapors in the solid state.

Effect of the π-linker on the performance of organic photovoltaic devices based on push–pull D–π–A molecules

The bulk heterojunction organic photovoltaic (OPV) devices based on 3T : PC₇₁BM (2 wt%, 1 : 1.75 w/w) exhibited a higher power conversion efficiency of 2.58% than DTT-based OPV devices.

π-Conjugated dithieno[3,2-b:2′,3′-d]pyrrole (DTP) oligomers for organic thin-film transistors

Two new molecules consisting of coplanar electron-donating dithieno[3,2-b:2′,3′-d]pyrrole (DTP) as the donor unit and electron-withdrawing dicyanovinylene as the acceptor block, DTP-L and DTP-S, were synthesized.

An Efficient and Recyclable Nanoparticle-Supported Cobalt Catalyst for Quinoxaline Synthesis

The syntheses of quinoxalines derived from 1,2-diamine and 1,2-dicarbonyl compounds under mild reaction conditions was carried out using a nanoparticle-supported cobalt catalyst. The supported nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity. No cobalt contamination could be detected in the products by AAS measurements, pointing to the excellent activity and stability of the Co nanomaterial.

The solvatochromism and aggregation-induced enhanced emission based on triphenylamine-propenone

The weak intermolecular interactions and the suppression of the intramolecular charge transfer result in the efficient aggregation-induced enhanced emission characteristic of PhO-TPA and PyO-TPA.

New organic donor-acceptor-π-acceptor sensitizers for efficient dye-sensitized solar cells and photocatalytic hydrogen evolution under visible-light irradiation

Two organic donor-acceptor-π-acceptor (D-A-π-A) sensitizers (AQ and AP), containing quinoxaline/pyrido[3,4-b]pyrazine as the auxiliary acceptor, have been. Through fine-tuning of the auxiliary acceptor, a higher designed and synthesized photoelectric conversion efficiency of 6.02% for the AQ-based dye-sensitized solar cells under standard global AM1.5 solar conditions was achieved. Also, it was found that AQ-Pt/TiO2 photocatalysts displayed a better rate of H2 evolution under visible-light irradiation (420 nm<λ<780 nm) because of the stability of the oxidized states and the lower rates of electron recombination. Importantly, sensitizers AQ and AP-Pt/TiO2 showed strong photocatalytic activity during continuous light soaking for 10 h with methanol as the sacrificial electron donor. Additionally, the processes of their intermolecular electron transfer were further investigated theoretically by using time-dependent DFT. The calculated results indicate that the auxiliary acceptor plays the role of an electron trap and results in broad spectral responses.

Synthesis and photophysical investigation of a series of push-pull arylvinyldiazine chromophores

A new series of push-pull arylvinyldiazines has been efficiently prepared by aldol condensation between the appropriate methyldiazine and aromatic aldehyde. The optical absorption and emission properties of these chromophores were studied in different solvents and media. These compounds act as polarity sensors with a strong positive emission solvatochromism. This behavior suggests a highly polar emitting state, which is characteristic of compounds that undergo an internal charge transfer upon excitation. These molecules also exhibit halochromic properties and are potential colorimetric and luminescence pH sensors. The second-order nonlinear properties have been investigated for some of the compounds, and large and positive μβ are obtained, in particular, for pyrimidine derivatives.