Aneta Slodek

Superacidic bromination enables the first selective K-region functionalization of 2,7-diazapyrene; substitution topology controls excited-state switching between locally excited and charge-transfer emission.

The newly symmetrically substituted by carbazole units N-ethylphenothiazine derivatives 4a-4g, which vary in the length of the alkyl chain at the carbazole substituents, were designed and synthesized. By methodically investigating the impact of the alkyl chain at the carbazole unit on the photophysical properties of these novel compounds, with support from TD/DFT calculations, their photophysical characteristics were analyzed across a range of solvents with varying polarity. In hexane through to acetonitrile, the fluorescent properties of compounds 4a-4g result in light emission from blue to pale green. The moderate charge-transfer in compounds is indicated by the positive solvatochromism observed in their emission spectra. The derivatives with medium-length alkyl chains (C4-C6) demonstrated optimal photophysical performance, including high quantum yields (up to 81%), long excited-state lifetimes, and strong absorption coefficients. Low-temperature measurements confirmed the persistence of fluorescence and the emergence of phosphorescence bands. Dipole moment analysis using Lippert-Mataga plots revealed a gradual increase in excited-state polarity with increasing alkyl chain length. Cytotoxicity tests confirmed that all derivatives were nontoxic up to 25 μM across various cancer and normal cell lines. Despite limited passive membrane permeability, fluorescence microscopy under mild permeabilizing conditions (Tween 20) revealed that derivatives 4b and 4c could serve as selective fluorescent probes for membrane integrity. The results underscore the importance of alkyl chain engineering in tailoring molecular properties, making these compounds promising candidates for optoelectronic and photonic applications. They hold promise for bioimaging applications, particularly in membrane-targeted diagnostics or responsive drug-delivery systems.

Novel star‐shaped derivatives of indolo[3,2,1‐jk]carbazole (ICz) are obtained and thoroughly studied. They incorporate large chromophores, specifically fluorene(ICz‐A), carbazole(ICz‐B), phenothiazine(ICz‐C), and phenothiazine‐carbaldehyde(ICz‐D), all with long alkyl chains attached to the ICz core via acetylene linkages. The impact of different donor‐acceptor substituents on optical, thermal, electrochemical, and electroluminescent properties of ICz derivatives has been systematically investigated and compared with the quantum chemical calculations. ICz derivatives in DCM solution exhibit photoluminescence across a spectrum, from deep blue to green. In the solid state, bathochromic shifts of the emission maxima were observed for all compounds, indicating interactions between molecules in the condensed phase. The ICz‐D exhibits the highest emission efficiency in the solid state, accompanied by the reduction in the FWHM of the emission peak, attributed to the distorted plane of this molecule. The presence of “butterfly” phenothiazine rings and the aldehyde groups prevents electron transfer through intermolecular channels by acting as efficient blockers. For all compounds, their ability for light emission under external voltage was tested, based on devices with a neat compound (ITO/PEDOT:PSS/ICz/Al) and with guest–host configuration (ITO/PEDOT:PSS/PVK:PBD:ICz/Al). In the electroluminescence spectra of all diodes, one emission band in the 450–800 nm range was detected. Moreover, some of them exhibited voltage‐dependent color variation.

This paper presents the results of a study on the modification of dye-sensitized solar cells (DSSCs) using various phenothiazine derivatives, N719, and a mixture of these. The influence of the solvent used to prepare the dye solution, as well as the use of a TiO2 blocking layer, the addition of a co-adsorbent, or a mixture of dyes with N719 are presented. Characterisation of photoanodes was carried out to determine the UV-Vis absorption properties, morphology, and photovoltaic parameters of the fabricated solar cells. The use of different solvents for the preparation of dye solutions resulted in DSSCs efficiencies in the range of 1.55–7.26%. The most advantageous was using an ACN:t-BuOH mixture, which provided the best efficiency. The application of further modifications in the form of the addition of chenodeoxycholic acid (CDCA), a blocking layer, and the use of a co-sensitization process resulted in an increase in the final efficiency to a value of 8.50%.

The knowledge of interactions between different molecules is undoubtedly the driving force of all contemporary biomedical and biological sciences. Chemical biology/biological chemistry has become an important multidisciplinary bridge connecting the perspectives of chemistry and biology to the study of small molecules/peptidomimetics and their interactions in biological systems. Advances in structural biology research, in particular linking atomic structure to molecular properties and cellular context, are essential for the sophisticated design of new medicines that exhibit a high degree of druggability and very importantly, druglikeness. The authors of this contribution are outstanding scientists in the field who provided a brief overview of their work, which is arranged from in silico investigation through the characterization of interactions of compounds with biomolecules to bioactive materials.

1,3,6,8-Tetrasubstituted pyrene derivatives with two types of substituents (4-(2,2-dimethylpropyloxy)pyridine, 1-decyl-1,2,3-triazole, 1-benzyl-1,2,3-triazole, and pyrazole), substituted in such a way that provides the long axial symmetry, are prepared and characterized in the present study. To the best of our knowledge, the pyrene derivative containing the same heteroaryl motif (triazole) but substituted by two various alkyls, straight decyl and benzyl-based side chains (C), is reported for the first time. For comparison, compounds with one kind of triazole motif and substituted pyridine or pyrazole groups were prepared (A and B). The photophysical properties of all molecules were evaluated by thermogravimetric analysis (TGA) and UV-Vis spectroscopy (absorption and emission spectra, quantum yields, and fluorescence lifetimes). The obtained results were compared to analogues substituted at the 1,3,6,8 positions by one kind of substituent and also with all the 1,3,6,8-tetrasubstituted pyrenes reported in the literature substituted by two kinds of substituents with a substitution pattern that provides long axial symmetry. In addition, theoretical studies based on DFT and TD-DFT were performed that supported the interpretation of the experimental results. The photophysical properties of tetrasubstituted pyrene derivatives having triazole units at the 1,8-positions, respectively, and other identical substituents at the 3,6 positions show the dominance of triazole units in the pyrene framework; the dominance is even higher in the case of the substitution of 1,3,6,8 positions by triazoles, but containing two various alkyls.