New 2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-2,2’-bipyridine-based co-polymer, synthesis, photophysical properties and response to metal cations

A new co-polymer based on fragments of 2-(2-pyridyl)monoazatriphenylene and 2,5-bis (2-ethylhexyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione was prepared by using the Sonogashira reaction. The photophysical properties of the polymer were studied. The presence of a strong bathochromic shift of the absorption and emission maxima in comparison with the previously described monomer units is shown. The polymer exhibits an intense “turn-off” response toward Cu2+ cations.

New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations

A set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-b] thiophene, as well as an alkylated benzotriazole unit were prepared and tested for dye-sensitized solar cells (DSSCs). For comparison purposes, the variation of the substitution pattern at the coumarin unit was analyzed with the natural product 6,7-dihydroxycoumarin (Esculetin) as well as 5,7-dihydroxycomarin in the case of the bithiophene dye. Crucial steps for extension of the conjugated system involved Sonogashira reaction yielding highly fluorescent molecules. Spectroscopic characterization showed that the extension of conjugation via the alkynyl bridge resulted in a strong red-shift of absorption and emission spectra (in solution) of approximately 73–79 nm and 52–89 nm, respectively, relative to 6,7-dimethoxy-4-methylcoumarin (labs = 341 nm and lem = 410 nm). Theoretical density functional theory (DFT) calculations show that the Lowest Unoccupied Molecular Orbital (LUMO) is mostly centered in the cyanoacrylic anchor unit, corroborating the high intramolecular charge transfer (ICT) character of the electronic transition. Photovoltaic performance evaluation reveals that the thieno [3,2-b] thiophene unit present in dye 8 leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best VOC (367 mV) and second best Jsc (9.28 mA·cm−2), surpassed only by dye 9b (Jsc = 10.19 mA·cm−2). This high photocurrent value can be attributed to increased donor ability of the 5,7-dimethoxy unit when compared to the 6,7 equivalent (9b).

Synthesis, Characterization and Anticancer Evaluation of Nitrogen Substituted 1-(3-Aminoprop-1-ynyl)-4-Hydroxyanthraquinone Derivatives

Anthraquinones are of significant interest due to their biological activity, coloring properties and synthetic applications. Here, we describe a mild and convenient method for modification of 1-ethynyl-4-hydroxyanthraquinone that was obtained from the Sonogashira reaction of 1-hydroxy-4-iodoanthraquinone with alkynes. The copper(I) catalyzed one-pot three component reaction (A3-coupling) of the new 1-ethynyl-4-hydroxyanthraquinone with secondary amines and formaldehyde was the main approach for the synthesis of nitrogen substituted 1-[3-(amino)prop-1-ynyl]-4-hydroxyanthraquinones. The influence of different substituent in the amine on reaction rate and yield has been evaluated. The cytotoxicity of 1-ethynyl-4-hydroxyanthraquinones was evaluated using the conventional MTT assay. Among all the compounds synthesized, anthraquinone-propargylamine derivatives 28, 29, 30 and 34 possess most promising cytotoxic potential towards glioblastoma cancer cells; compounds 14 and 19 shown selectivity towards the prostate cancer cells DU-145, and 18, and 24 – towards breast cancer cells MCF-7. The grown inhibition on these cancer cells of 18 and 24 was comparable to those of standard drug Doxorubicin. Molecular modeling of new compounds in DNA G-quadruplex binding site was performed to help understand the observed SAR trends.