Contributing to Biochemistry and Optoelectronics: Pyrrolo[1',2':2,3]imidazo[1,5-a]indoles and Cyclohepta[4,5]pyrrolo[1,2-c]pyrrolo[1,2-a]imidazoles via [3+2] Annulation of Acylethynylcycloalka[b]pyrroles with Δ1-Pyrrolines.

Available pyrrolylalkynones with tetrahydroindolyl, cycloalkanopyrrolyl, and dihydrobenzo[g]indolyl moieties, acylethynylcycloalka[b]pyrroles, are readily annulated with Δ1-pyrrolines (MeCN/THF, 70 °C, 8 h) to afford a series of novel pyrrolo[1',2':2,3]imidazo[1,5-a]indoles and cyclohepta[4,5]pyrrolo[1,2-c]pyrrolo[1,2-a]imidazoles functionalized with an acylethenyl group in up to an 81% yield. This original synthetic approach contributes to the arsenal of chemical methods promoting drug discovery. Photophysical studies show that some of the synthesized compounds, e.g., benzo[g]pyrroloimidazoindoles, are prospective candidates for TADF emitters of OLED.

Application of meso-CF3-Fluorophore BODIPY with Phenyl and Pyrazolyl Substituents for Lifetime Visualization of Lysosomes.

A bright far-red emitting unsymmetrical meso-CF3-BODIPY fluorescent dye with phenyl and pyrazolyl substituents was synthesized by condensation of trifluoropyrrolylethanol with pyrazolyl-pyrrole, with subsequent oxidation and complexation of the formed dipyrromethane. This BODIPY dye exhibits optical absorption at λab ≈ 610-620 nm and emission at λem ≈ 640-650 nm. The BODIPY was studied on Ehrlich carcinoma cells as a lysosome-specific fluorescent dye that allows intravital staining of cell structures with subsequent real-time monitoring of changes occurring in the cells. It was also shown that the rate of uptake by cells, the rate of intracellular transport into lysosomes, and the rate of saturation of cells with the dye depend on its concentration in the culture medium. A concentration of 5 µM was chosen as the most suitable BODIPY concentration for fluorescent staining of living cell lysosomes, while a concentration of 100 µM was found to be toxic to Ehrlich carcinoma cells.

Theoretical Investigation of Carbon Dioxide Adsorption on Li+-Decorated Nanoflakes.

Recently, the capture of carbon dioxide, the primary greenhouse gas, has attracted particular interest from researchers worldwide. In the present work, several theoretical methods have been used to study adsorption of CO2 molecules on Li+-decorated coronene (Li+@coronene). It has been established that Li+ can be strongly anchored on coronene, and then a physical adsorption of CO2 will occur in the vicinity of this cation. Moreover, such a decoration has substantially improved interaction energy (Eint) between CO2 molecules and the adsorbent. One to twelve CO2 molecules per one Li+ have been considered, and their Eint values are in the range from -5.55 to -16.87 kcal/mol. Symmetry-adapted perturbation theory (SAPT0) calculations have shown that, depending on the quantity of adsorbed CO2 molecules, different energy components act as the main reason for attraction. AIMD simulations allow estimating gravimetric densities (GD, wt.%) at various temperatures, and the maximal GDs have been calculated to be 9.3, 6.0, and 4.9% at T = 77, 300, and 400 K, respectively. Besides this, AIMD calculations validate stability of Li+@coronene complexes during simulation time at the maximum CO2 loading. Bader's atoms-in-molecules (QTAIM) and independent gradient model (IGM) techniques have been implemented to unveil the features of interactions between CO2 and Li+@coronene. These methods have proved that there exists a non-covalent bonding between the cation center and CO2. We suppose that findings, derived in this theoretical work, may also benefit the design of novel nanosystems for gas storage and delivery.

Effect of methyl substituents on the electronic transitions in simple meso-aniline-BODIPY based dyes: RI-CC2 and TD-CAM-B3LYP computational investigation.

The S0→Si, i=1-5 electronic transitions of four 8-(4-aniline)-BODIPY and four 8-(N,N-dimethyl)-BODIPY dyes, differ by number and position of methyl substituents in the BODIPY frame, were investigated theoretically using ab initio the coupled cluster doubles (CC2) and TD-CAM-B3LYP methods. Methyl substituents in the BODIPY frame and the aniline fragment at the meso position disturb energy of local excitations S0→S1, S0→S3, and S0→S4 weakly in comparison with the fully unsubstituted BODIPY molecule. These transitions in experimental spectra form the most long-wave absorption bands at ca. 500nm as well as absorption bands in the region of 300-400nm. At the same time, the presence of aniline fragments leads to the appearance of new S0→S2 transitions of the charge transfer character in electronic spectra of BODIPYs. We also found a linear relationship between vertical energy of these charge transfer transitions and the electron donating power of an aniline fragment and electron accepting power of the BODIPY core depending on the number and position of methyl groups. The CC2 method provides the best overall description of the excitation energies in line with the experimental observations. On average, the quality of TD-CAM-B3LYP is almost equal to that of CC2, however the TD method with the CAM-B3LYP functional slightly underestimates the CT excitation energy.

General route to symmetric and asymmetric meso-CF3-3(5)-aryl(hetaryl)- and 3,5-diaryl(dihetaryl)-BODIPY dyes.

A general efficient route to hitherto inaccessible symmetric and asymmetric meso-CF(3)-BODIPY dyes has been developed. The key stages include the reduction of available 2-trifluoroacetylpyrroles to the corresponding alcohols which are further condensed with pyrroles. The method allows the BODIPY with 3(5)aryl(hetaryl) and 3,5-diaryl(hetaryl) substituents to be readily assembled. The BODIPY dyes synthesized fluoresce (Φ(f) = 0.56-1.00) in the 560-680 nm region.

Synthesis and optical properties of 2-(benzo[b]thiophene-3-yl)pyrroles and a new BODIPY fluorophore (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene).

2-(Benzo[b]thiophene-3-yl)-1-vinylpyrrole has been synthesized directly from 3-acetylbenzo[b]thiophene oxime and acetylene (flow system, KOH-DMSO, 120 degrees C, 5 h) in 68% yield. Devinylation of the synthesized pyrrole (Hg(OAc)(2), NaBH(4), 50 degrees C) led to the corresponding 2-(benzo[b]thiophene-3-yl)pyrrole in 63% yield. Trifluoroacetylation of both the pyrroles with trifluoroacetic anhydride (80 degrees C, 1 h) gave the corresponding 5-trifluoroacetyl pyrroles in 97% and 76% yields, respectively. 2-(Benzo[b]thiophene-3-yl)pyrrole was reacted subsequently with mesityl aldehyde, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and BF(3)OEt(2) to afford 4,4-difluoro-3,5-di(benzo[b]thiophene-3-yl)-8-mesityl-4-bora-3a,4a-diaza-s-indacene, a representative of the novel BODIPY fluorophore family (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene), in 34% overall yield. The synthesized pyrroles exhibit promising optical properties (absorption and emission spectra, nonlinear optical (NLO) features), superior to existing analogues. The BODIPY fluorophore displays an intense red-shifted fluorescence emission in CH(2)Cl(2) (625 nm, 0.84 fluorescence quantum yield) that is fully preserved in the solid state.