Eco-friendly K-10 Clay-Mediated [3 + 3] Spiroannulation of Morita-Baylis-Hillman Adduct of Isatin with Anthracene: Synthesis of Green Fluorophore Compounds

An easy and simple spiroannulation of the Morita-Baylis-Hillman adduct of isatin derivatives with anthracene was achieved in moderate-to-good yields (37-75%). The spiroderivatives synthesized in this work exhibited green fluorescence properties. The reaction occurred in metal-free eco-friendly K-10 clay-mediated conditions. The final products have multiple structural features such as 3-spirooxindole, fluorophoric anthracene, phenanthracene, phenalene, and perylene cores.

Transforming Hetera-Buckybowls into Chiral Conjugated Polycycles Incorporating Epoxycyclooctadiene: a Two-Step Approach

Chiral π-conjugated polycycles have garnered increasing attention due to versatile applications in optoelectronic materials and biological sciences. In this study, we report the synthesis of chiral π-conjugated polycycles incorporating a chiral epoxycyclooctadiene moiety. Our synthetic strategy capitalizes on the novel reactions of hetera-buckybowl triselenasumanene (TSS) and is achieved in two-step manner. Firstly, the TSS is regio-selectively transformed into its ortho-quinone form. Subsequently, the nucleophilic addition reactions of TSS ortho-quinone by phenylethynides are metal ion-dependent. When utilizing (phenylethynyl)magnesium bromide as the nucleophile, two phenylethynyls are furnished onto the edged benzene ring of TSS. When the nucleophile is (phenylethynyl)lithium, a cascade of nucleophilic addition, intermolecular electron-transfer, ring-opening, and tetradehydro-Diels-Alder (TDDA) reactions occur sequentially in one-pot, ultimately affording chiral π-conjugated polycycles featuring the epoxycyclooctadiene moiety as an integral part of their backbones. This work represents a step forward in the synthesis of chiral π-conjugated polycycles using TSS as synthon.

Electroactive Dyes Based on 1,8-Naphthalimide with Acetylene Linkers as Promising OLED Materials - the Relationship Between Structure and Photophysical Properties

Four A-π-D-π-A type small organic molecules with 1,8-naphthalimide motifs were successfully synthesised. The designed compounds are built of two 1,8-naphthalimide units linked via ethynyl π-linkages with selected functionalised donor motifs i. e. 2,2'-bithiophene, fluorene, phenothiazine and carbazole derivative. The synthesis based on Sonogashira cross-coupling allowed us to obtain the presented dyes with good yields. The resulting symmetrical small molecules' optical, electrochemical and thermal properties were thoroughly investigated, and their potential applicability for the OLED devices was demonstrated. In addition, the relationship between molecular structure and properties was considered by employing experimental and theoretical studies. As a result of using various donor groups, it was possible to achieve efficient electroluminescence in the range from green (DEV4) to orange-red light (DEV3) with a maximum luminance of 3 820 cd/m2 for DEV4. Upon the insertion of an acetylene linker to the designed molecules, the free rotation of D and A fragments, and hence the effective π-electron communication within the entire molecule, is possible, which was confirmed by DFT studies. The obtained dyes are characterised by high thermal stability, reversible oxidation-reduction process, satisfactory optoelectronic properties and good solubility in organic solvents, which is advisable for the application in small molecular organic light-emitting diodes (SM-OLEDs) technology.

Room-Temperature, Copper-Free, and Amine-Free Sonogashira Reaction in a Green Solvent: Synthesis of Tetraalkynylated Anthracenes and In Vitro Assessment of Their Cytotoxic Potentials

The multifold Sonogashira coupling of a class of aryl halides with arylacetylene in the presence of an equivalent of Cs₂CO₃ has been accomplished using a combination of Pd(CH₃CN)₂Cl₂ (0.5 mol %) and cataCXium A (1 mol %) under copper-free and amine-free conditions in a readily available green solvent at room temperature. The protocol was used to transform several aryl halides and alkynes to the corresponding coupled products in good to excellent yields. The rate-determining step is likely to involve the oxidative addition of Ar-X. The green protocol provides access to various valuable polycyclic aromatic hydrocarbons (PAHs) with exciting photophysical properties. Among them, six tetraalkynylated anthracenes have been tested for their anticancer properties on the human triple-negative breast cancer (TNBC) cell line MDA-MB-231 and human dermal fibroblasts (HDFs). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to find out the IC₅₀ concentration and lethal dose. The compounds being intrinsically fluorescent, their cellular localization was checked by live cell fluorescence imaging. 4',6-Diamidino-2-phenylindole (DAPI) and propidium iodide (PI) staining was performed to check apoptosis and necrosis, respectively. All of these studies have shown that anthracene and its derivatives can induce cell death via DNA damage and apoptosis.

Efficient access to materials-oriented aromatic alkynes via the mechanochemical Sonogashira coupling of solid aryl halides with large polycyclic conjugated systems

Sonogashira coupling represents an indispensable tool for the preparation of organic materials that contain C(sp)-C(sp2) bonds. Improving the efficiency and generality of this methodology has long been an important research subject in materials science. Here, we show that a high-temperature ball-milling technique enables the highly efficient palladium-catalyzed Sonogashira coupling of solid aryl halides that bear large polyaromatic structures including sparingly soluble substrates and unactivated aryl chlorides. In fact, this new protocol provides various materials-oriented polyaromatic alkynes in excellent yield within short reaction times in the absence of bulk reaction solvents. Notably, we synthesized a new luminescent material via the mechanochemical Sonogashira coupling of poorly soluble Vat Red 1 in a much higher yield compared to those obtained using solution-based conditions. The utility of this method was further demonstrated by the rapid synthesis of a fluorescent metal-organic framework (MOF) precursor via two sequential mechanochemical Sonogashira cross-coupling reactions. The present study illustrates the great potential of Sonogashira coupling using ball milling for the preparation of materials-oriented alkynes and for the discovery of novel functional materials.

Bimetallic ethynylanthracenyl functionalised carbynes

Mono- and bimetallic anthracenes functionalised by alkynyl and alkylidynyl substituents are obtained via sequential cross-coupling reactions of the 9-bromoanthracenyl carbyne [W{CC(C₆H₄)₂CBr}(CO)₂(Tp*)].

Multi-fold Sonogashira coupling: a new and convenient approach to obtain tetraalkynyl anthracenes with tunable photophysical properties

For the first time, a direct single-step one-pot route to access nine new symmetric tetraalkynylated anthracenes via Pd(CH₃CN)₂Cl₂/cataCXium®A catalyzed tetra-fold Sonogashira coupling is reported. Five of these tetraalkynylated anthracenes have been crystallographically characterized, with two of them exhibiting multiple interactions that significantly shorten the inter-planar distances in the solid-state structure. The rich photophysical properties exhibited by these molecules hold immense promise for future applications in sensors and optoelectronic devices. Two of the considered tetraalkynylated anthracenes comprising a D-π-A-π-D motif demonstrate solvatochromism and halochromism, with one of them showing a low bandgap of 1.79 eV. The remaining compounds demonstrate bandgaps in the range of 1.79-2.04 eV.

Symmetric and non-symmetric anthracen-diyl bis(alkylidynes)

Three examples of 9-bromo-10-(alkylidynyl)anthracenes, [W{CC(C₆H₄)₂CBr}(CO)₂(L)] (L = hydrotris(dimethylpyrazol-1-yl)borate Tp*, hydrotris(pyrazol-1-yl)borate Tp, hydrotris(2-mercapto-N-methylimidazol-1-yl)borate Tm) were prepared via modified Fischer-Mayr acyl oxide-abstraction protocols. With a sufficiently bulky ancillary ligand (L = Tp*) the aryl bromide is ammenable to cross-coupling reactions that enable more elaborate derivatives to be prepared. These including symmetric bis(alkylidynyl)anthracenes as well as non-palindromic examples bearing disparate metals and/or co-ligands. In contrast, these couplings fail for smaller ligands (L = Tp, Tm) where it was found that Pd⁰ or Pt⁰ were instead able to coordinate across two WC bonds to give trimetallic bow-tie complexes, [W₂M{μ-CC(C₆H₄)₂CBr}₂(CO)₄(L)₂] (M = Pd, Pt; L = Tp, Tm).

Zn- and Cd-based coordination polymers with a novel anthracene dicarboxylate ligand for highly selective detection of hydrogen peroxide

A one-dimensional {[Zn(L)(DMF)2]}n (1) and a three-dimensional {[Cd(L)(DMF)]·DMF}n (2) coordination polymer based on the novel anthracene derivative H2L (H2L = 4,4'-(9,10-anthracenediyl)dicinnamic acid) were obtained by solvothermal synthesis and charaterised by single-crystal and powder X-ray diffraction, thermogravimetry, and infrared spectroscopy. The anthracene derivative H2L and coordination polymers 1 and 2 were used to modify a glassy carbon electrode and as such served as an active material for detection of H2O2. Cyclic voltammograms in the potential range from 0 to -0.5 V revealed concentration-dependent cathodic current in all three cases with a lower detection limit of 200 μM. The electrode modified with compound 2 showed the best performance towards hydrogen peroxide detection. The results suggest that the development of electrodes modified with inorganic polymers based on highly conjugated ligands can serve as potential electrocatalytic materials.

Non-photoisomerizable butterfly shaped tetrasubstituted azobenzenes: synthesis and photophysical studies

The trans-azobenzene (AB) substituted derivatives with bulky carbazole (1), phenothiazine (2), and phenyl (3) have been synthesized to understand the effect of steric crowding around the –NN– linkage on the photoisomerization process.

Synthesis, one/two-photon optical and electrochemical properties and the photopolymerization-sensitizing effect of anthracene-based dyes: influence of the donor groups

Anthracene-based dyes with different donor groups: optical and electrochemical properties and their application in dye-sensitized photopolymerization.

Palladacycle-Catalyzed Triple Suzuki Coupling Strategy for the Synthesis of Anthracene-Based OLED Emitters

The development of the site-selective Suzuki-Miyaura cross-coupling of dibromoanthracene as an efficient strategy toward organic light emitting diodes (OLEDs) is disclosed in this article. An unprecedented step-economic palladacycle-promoted triple Suzuki coupling protocol allowed the synthesis of three new OLED emitters and could prove to be a useful general strategy for researchers working in this field. Characterization of the synthesized molecules by UV-vis spectroscopy and thermogravimetric analysis-differential scanning calorimetry followed by density functional theory studies of the different properties strongly confirms the derivatives possess more significant hole mobility character than electron transfer capability.

Synthesis of novel profluorescent nitroxides as dual luminescent-paramagnetic active probes

Profluorescent nitroxides containing 2,5-diaryl-1,3,4-oxadiazoles as fluorophore units were synthesized and characterized as actively responsive probes to reducing agents.