Radical-Triggered Bicyclization and Aryl Migration of 1,7-Diynes with Diphenyl Diselenide for the Synthesis of Selenopheno[3,4-c]quinolines

The translocation of an aryl group from selenium into carbon enabled by the cleavage of the C-Se bond is reported by using nitrogen atom-linked 1,7-diynes and diaryl diselenides as starting materials, leading to various selenophene derivatives in a regioselective manner. This method enables the construction of two C-Se bonds and two C-C bonds through sequential radical bicyclization and 1,2-aryl migration under metal-free conditions. Control experiments and mechanistic studies suggest that this reaction proceeds through the cleavage of the inert C(Ph)-Se bond, facilitating the aryl translocation process. This transformation enables the one-step conversion of simple diselenides into diverse selenopheno[3,4-c]quinolines via a radical-promoted process, holding significant potential for new seleniferous heterocycles.

Synthesis of 2,5-disubstituted selenophenes via a copper-catalyzed regioselective [2+2+1] cyclization of terminal alkynes and selenium

Herein, a straightforward method for the synthesis of 2,5-disubstituted selenophenes via [2+2+1] cyclization of easily accessible terminal alkynes and elemental selenium has been developed. This reaction features high atom- and step-economy, excellent regioselectivity, good functional group tolerance and the use of stable and non-toxic selenium as a selenium source. A series of control experiments suggests that the reaction might undergo Glaser coupling reaction of two molecules of alkynes, followed by insertion of H₂Se and subsequent cyclization. Moreover, the newly formed products can be further converted to diverse conjugated selenophene-based derivatives, demonstrating their potential applications in organic synthesis and materials science.

Synthesis and photophysical properties of selenopheno[2,3-b]quinoxaline and selenopheno[2,3-b]pyrazine heteroacenes

In this paper, we report the novel synthesis of three different heterocycles, namely 2-arylselenopheno[2,3-b]quinoxaline, 3-(aryl/alkylselanyl)-2-arylselenopheno[2,3-b]quinoxaline and 6-phenyl-7-(arylselanyl)selenopheno[2,3-b]pyrazine derivatives, from the corresponding 2,3-dichloroquinoxaline and 2,3-dichloropyrazine derivatives. Furthermore, photophysical properties were investigated to study the effect of heteroatoms on UV-absorbance and fluorescence properties.

In situ air oxidation and photophysical studies of isoquinoline-fused N-heteroacenes

An efficient, metal free and environment friendly synthesis of isoquinoline-fused benzimidazole has been developed via in situ air oxidation. Also, syntheses of isoquinoline-fused quinazolinone heteroacenes were successfully achieved. The synthesized isoquinoline-fused benzimidazole and isoquinoline-fused quinazolinone derivatives showed λmax, Fmax and Φf values in the ranges 356-394 nm, 403-444 nm and 0.063-0.471, respectively, in CHCl3.

Time dependent aggregation induced emission enhancement and the study of molecular packing in closely related azo-phenol BODIPY species

Fluorescent azo-phenol BODIPYs (1-3) have been obtained by the substituent (-OCH₃/-CH₃) directed synthesis of ortho (L1) and para (L2-L3) azo-phenol aldehydes. These display aggregation caused quenching (ACQ, 1) and aggregation induced emission enhancement (AIEE, 2 and 3) depending on the position of azo relative to the phenolic hydroxyl group. An intriguing time dependent morphological transition from nanospheres to ordered nanorods and subsequent emission changes in AIEE active azo-phenol BODIPYs have been successfully realized by time dependent fluorescence, scanning electron (SEM), transmission electron (TEM) and fluorescence optical microscopy (FOM) studies. The existence of one-dimensional (1D) nanorods as ultimate species in these compounds (2-3) has been supported by crystal packing patterns. Diverse aggregated forms and hierarchical nanostructures have been related to variable extents of fluorescence enhancement. The plausible charge transfer process and its role in AIEE have been supported by DFT studies.

Self-Assembled BODIPY-Based Iridium Metallarectangles: Cytotoxicity and Propensity to Bind Biomolecules

A new 4-ethynylpyridine 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based ligand L, which was synthesized by means of the Sonogashira coupling method, was used to obtain two new [2+2] iridium-based metallarectangles, 3 and 4. Ligand L and metallarectangles 3 and 4 were fully characterized through various analytical techniques. The structure of rectangle 4 was further confirmed by single-crystal X-ray diffraction analysis, which showed the formation of an expected [2+2] supramolecule, in which the iridium metal centers were bridged with ligand L to form the desired metallarectangle 4. In the context of the growing biological interest in metallarectangles, rectangle 4 was found to be highly active against two types of cancer cells, with IC₅₀ values almost threefold superior to those of cisplatin. Both 3 and 4 showed dose-dependent abilities to bind bovine serum albumin and salmon sperm DNA; this indicated their tendency to interact with such biomolecules as a potential mode of action.

Synthesis of thieno[2,3-c]acridine and furo[2,3-c]acridine derivatives via an iodocyclization reaction and their fluorescence properties and DFT mechanistic studies

In this paper, we report the novel synthesis of thieno[2,3-c]acridine and furo[2,3-c]acridine derivatives via intramolecular iodocyclization reaction. The thieno[2,3-c]acridine derivatives exhibited blue fluorescence in hexane.

Self-Assembled Novel BODIPY-Based Palladium Supramolecules and Their Cellular Localization

Four new palladium metal supramolecules with triangular/square architectures derived from boron dipyrromethane (BODIPY) ligands were synthesized by self-assembly and fully characterized by ¹H and ³¹P NMR, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction. These supramolecules were more cytotoxic to brain cancer (glioblastoma) cells than to normal lung fibroblasts. Their cytotoxicity to the glioblastoma cells was higher than that of a benchmark metal-based chemotherapy drug, cisplatin. The characteristic green fluorescence of the BODIPY ligands in these supramolecules permitted their intracellular visualization using confocal microscopy, and the compounds were localized in the cytoplasm and on the plasma membrane.

Pyrene–fluorescein-based colour-tunable AIE-active hybrid fluorophore material for potential live cell imaging applications

A novel hybrid fluorophore (FHPY) has been synthesized based on two standard fluorescent hydrophobic–hydrophilic molecules, viz. pyrene and fluorescein, with an objective to tune the AIE along with the morphology and live cell imaging.

Fluorophore-functionalized graphene oxide with application in cell imaging

A fluorescent carbon material with excellent fluorescence performances and a nearly nucleus-staining was prepared by a simple method.

Rational design of asymmetric red fluorescent probes for live cell imaging with high AIE effects and large two-photon absorption cross sections using tunable terminal groups

In this work, we report the synthesis of a family of donor-acceptor (D-A) π-conjugated aggregation-induced red emission materials (TPABT, DTPABT, TPEBT and DTPEBT) with the same core 2,2-(2,2-diphenylethene-1,1-diyl)dithiophene (DPDT) and different amounts and different strengths of electron-donating terminal moieties. Interestingly, TPABT and TPEBT, which have asymmetric structures, give obviously higher solid fluorescence quantum efficiencies in comparison with those of the corresponding symmetric structures, DTPABT and DTPEBT, respectively. In particular, the thin film of TPEBT exhibited the highest fluorescence quantum efficiency of ca. 38% with the highest αAIE. Moreover, TPEBT and DTPEBT with TPE groups showed two-photon absorption cross-sections of (δ) 1.75 × 103 GM and 1.94 × 103 GM at 780 nm, respectively, which are obviously higher than the other two red fluorescent materials with triphenylamine groups. Then, the one-photon and two-photon fluorescence imaging of MCF-7 breast cancer cells and Hela cells, and cytotoxicity experiments, were carried out with these red fluorescent materials. Intense intracellular red fluorescence was observed for all the molecules using one-photon excitation and for TPABT using two-photon excitation in the cell cytoplasm. Finally, TPEBT is biocompatible and functions well in mouse brain blood vascular visualization. It is indicated that these materials can be used as a specific stain fluorescent probe for live cell imaging.

Ratiometric detection and imaging of endogenous hypochlorite in live cells and in vivo achieved by using an aggregation induced emission (AIE)-based nanoprobe

An AIE-based fluorescent nanoprobe (MTPE-M) has been developed and used for ratiometric detection of hypochlorite with high selectivity and sensitivity. More importantly, its application in live cells and zebrafish for ratiometric imaging of endogenous ClO(-) has also been achieved.

Novel BODIPY-based Ru(ii) and Ir(iii) metalla-rectangles: cellular localization of compounds and their antiproliferative activities

The synthesis and antiproliferative activities of novel BODIPY-based Ru and Ir rectangles are presented.

Aggregation-induced emission enhancement and cell imaging of a novel (carbazol-N-yl)triphenylamine–BODIPY

The AIEE fluorogen BCPA–BODIPY emits strong red fluorescence and shows a good uptake by MCF-7 cells.

A ratiometric fluorescent system for carboxylesterase detection with AIE dots as FRET donors

A ratiometric fluorescence CaE assay was developed with AIE dots as donors in the FRET process for the first time, which is capable of detecting esterase in human serum.