This study focuses on the synthesis of a new spiropyran with an azomethine moiety. The synthesis was carried out by a condensation reaction between formyl-substituted spiropyran and para-anisidine. A detailed study using NMR, FT-IR, and mass spectroscopy was carried out to confirm the structure of the resulting azomethine. Particular attention was paid to single crystal X-ray diffraction analysis. Hirshfeld surface calculations were performed to elucidate the nature and relative contributions of the intermolecular interactions that govern crystal packing. Since the molecule has two fragments prone to photoisomerization, one of the main objectives of the study was to study its behavior under UV irradiation. Establishing the relationship between the structure and properties of such compounds is an important and actual task for the molecular design of organic photochromes. During spectral-kinetic studies the target compound showed unexpected photochromic behavior different from standard formation of a merocyanine isomer. With support of quantum chemical calculations, the predominant photoactivation path through azometine fragment cis-trans isomerization was established. Due to the fact that the molecule contains several structural fragments that determine its potential activity against bacteria and biofilms, as well as the inhibition of β-secretase, we have given a preliminary assessment of the prospects for using the resulting azomethine for pharmaceutical purposes using the molecular docking method.

New Zn(II) and Cd(II) complexes based on N-[2-[(E)-2-furylmethyliminomethyl]phenyl]-4-methyl-benzenesulfonamide were synthesized. The structures and physicochemical properties of the complexes were studied using single-crystal X-ray diffraction analysis, 1H nmR, IR, and UV-Vis spectroscopy and DFT calculations. It was shown that the two deprotonated ligands chelate the metal ions through the nitrogen atoms of the tosylamine and azomethine fragments. The coordination geometry around the Zn(II) and Cd(II) ions is highly distorted tetrahedron. Hirshfeld surface analysis was used to visualize and quantify intermolecular interactions, including hydrogen bonds, van der Waals forces, and pi-pi stacking in the crystal structures. The photoluminescent properties of the complexes were also investigated.

Spiropyrans are a promising class of organic photochromic compounds that are currently of great interest, especially in the fields of molecular electronics, chemosensing, photopharmacology and theranostics. One of the key challenges hindering the widespread practical application of these compounds involves enhancing the stability of the active form and shifting its absorption maximum toward the far-red or even near-infrared (NIR) region of the spectrum. In this study, a series of new spiropyran derivatives with elongated conjugation chains and halogen atoms was obtained. These derivatives exhibit exceptional spectral and kinetic properties, such as NIR-absorption and emission, as well as an extended lifetime of the active form. Of particular interest is the complex case of multiple electronic effects observed in these compounds, which was extensively studied by theoretical modeling. Additionally, we conducted initial photodriven toxicity studies of target compounds using bacterial lux-biosensors, which confirmed their potential as theranostic agents. The results obtained provide valuable insights into the structural factors that determine the properties of spiropyrans, contributing to the rational design of photochromic compounds for various applications.

The development of noninvasive methods for bladder cancer identification remains a critical clinical need. Recent studies have shown that atomic force microscopy (AFM), combined with pattern recognition machine learning, can detect bladder cancer by analyzing cells extracted from urine. However, these promising findings were limited by a relatively small patient cohort, resulting in modest statistical significance. In this study, we corroborated the AFM technique’s capability to identify bladder cancer cells with high accuracy using a controlled model system of genetically purified human bladder epithelial cell lines, comparing cancerous cells with nonmalignant controls. By processing AFM adhesion maps through machine learning algorithms, following previously established methods, we achieved an area under the ROC curve (AUC) of 0.97, with 91% accuracy in cancer cell identification. Furthermore, we enhanced cancer detection by incorporating multiple imaging channels recorded with AFM operating in Ringing mode, achieving an AUC of 0.99 and 93% accuracy. These results demonstrated strong statistical significance (p < 0.0001) in this well-defined model system. While this controlled study does not capture the biological variation present in clinical settings, it provides independent support for AFM-based detection methods and establishes a rigorous technical foundation for further clinical development of AFM imaging-based methods for bladder cancer detection.

The synthesis of 1 : 1 and 1 : 2 complexes of Zn( ii ) hexafluoroacetylacetonate with sterically crowded triphenodioxazines (TPDO) is described, and the compounds are characterized using single-crystal X-ray crystallography, NMR, and IR spectroscopy.

Photopharmacology is a young and rapidly developing field of research that offers significant potential for new insights into targeted therapy. While it primarily focuses on cancer treatment, it also holds promise for other diseases. The key feature of photopharmacological agents is the presence of a photosensitive and biologically active component in the same molecule. In our current study, we synthesized a spiropyran-based meta-stable state photoacid containing a fragment of β-estradiol. This compound exhibits negative photochromism and photocontrolled fluorescence under visible-light irradiation due to the initial stabilization of its self-protonated form in solution. We conducted comprehensive biological studies on the HeLa cells model to assess the short- and long-term cytotoxicity of the photoacid, its metabolic effects, its influence on signaling and epithelial-mesenchymal transition super-system pathways, and the proportion of the population enriched with cancer stem cells. Our findings reveal that this derivative demonstrates low cytotoxicity to HeLa cells, yet it is capable of dramatically reducing malignant cells side population enriched in cancer stem cells. Additionally, appropriate structural modification lead to an increase in some other biological effects compared to β-estradiol. In particular, our substance possesses rare properties of AP-1 suppression and demonstrates some pro-oxidant and metabolic effects, which can be regulated by visible light irradiation. As a result, the new estradiol-based photoacid may be considered a promising multi-acting photopharmacological agent for the next-generation anti-cancer research & development.

A convenient method for the synthesis of a series of 2-(arylamino)-3H-phenoxazin-3-ones based on the nucleophilic substitution reaction between sterically crowded 3H-phenoxazin-3-one and arylamines performed by short-term heating of the melted reactants at 220–250 °C is described, and the compounds were characterized by means of single-crystal X-ray crystallography, NMR, UV–vis, and IR spectroscopy, as well as cyclic voltammetry. The reaction with o-amino-, o-hydroxy-, and o-mercapto-substituted arylamines widened the scope and provided an access to derivatives of N,O- and N,S-heteropentacyclic quinoxalinophenoxazine, triphenodioxazine and oxazinophenothiazine systems.

Spiropyran salts containing a cationic vinyl-3H-indolium moiety are characterized by NIR absorption and fluorescence of their merocyanine forms. This feature makes them promising fluorescent probes and markers for bioimaging. The article focuses on the synthesis and study of the spectral, kinetic and toxic characteristics of such compounds with respect to various substituents in different moieties and the type of anion. A detailed analysis of the acquired data made it possible to draw some important conclusions regarding the influence of structural factors, which will be very useful for the further rational design of such derivatives. In particular, it was shown that the counterion has minimal effect on the spectral and kinetic characteristics of the dyes but dramatically affects the toxicity of the compounds. Following selection of the most appropriate compounds, bioimaging experiments were carried out to visualize planktonic bacteria and bacterial biofilms of E. coli and A. calcoaceticus. The ability to visualize biofilms is critical for the diagnosis of chronic diseases. By the results of molecular docking a theoretical interaction pattern between spiropyran molecules and DNA was proposed.

Reactions of 12H-quinoxaline[2,3-b]phenoxazine (QOPO) derivatives with the CoII and ZnII hexafluoroacetylacetonates accompanied by protonation of the starting bases result in stable complexes [QOPOH]+[M(hfac)3]− whose structure was determined by X-ray diffraction and by 1H and 15N NMR spectroscopy. The complexes are characterized by long-wavelength absorption (560–664 nm) and fluorescence in the red region (λfl = 674–805 nm). The relative energies of the protonated tautomers N(14)—H and N(7)—H were determined using the results of B3LYP–D3BJ/6-311G++(d,p) density functional calculations with inclusion of D3BJ dispersion correction. A SQUID magnetometry study of the static and dynamic magnetic properties of the CoII complex revealed that it behaves as a field-induced single-ion magnet.

The synthesis of a new symmetric bis(spiropyran) of the indoline series existing as an equilibrium mixture of isomeric forms in various organic solvents is described. This equilibrium was in detail studied by dynamic NMR spectroscopy. In particular, the equilibrium constants were found at various temperatures, and the thermal effects of isomerization processes were calculated. The thermal transformations were studied by quantum chemical modeling. As a result, possible isomerization pathways were proposed and the observed ratio of the forms in the NMR spectra was explained. Photo- and thermochromic transformations were studied by UV spectroscopy, which revealed positive photochromic properties of the target compound. The observed changes in the absorption spectra with increasing temperature are completely consistent with the results of NMR studies. The nature of the absorption bands observed in the spectra was explained using time-dependent density functional theory (TD-DFT) calculations. The surface-enhanced Raman scattering (SERS) spectra of the synthesized compound on the surface of silver nanoparticles were detected and analyzed before and after UV irradiation to determine prospects for using similar bis(spiropyrans) as SERS markers and probes.

Recently the need for smart materials has been extremely growing, and the development of materials with appropriate characteristics has become one of the main challenges. Heptamethine cyanine dyes are widely used in theranostics and photovoltaics due to their remarkable optical properties. However, they are characterized by "rigid" non-changable properties. The main aim of the current study is to unveil correlation between structure and optical properties in the range of vinyl-3H-indolium substituted spiropyrans, which can be considered as the closest analogs of heptamethine cyanines with the photocontrolable optical and fluorescent properties. The effects of substitution in indoline and 2H-chromene cycles, as well as anion change are under the study. To achieve this goal, a series of spiropyran iodides and perchlorates with methyl, methoxy substituents or fluorine atom in position 6 ', as well as a conjugated vinyl-3H-indolium fragment in position 8 ', were synthesized. The structure of the compounds was carefully studied using SC XRD, NMR, IR and mass spectroscopy. Then, studies on absorption and photoluminescence characteristics, as well as photochromic behavior were carried out. A series of spiropyran iodides and perchlorates with methyl, methoxy and fluorine substituents in position 6 ', as well as a conjugated vinyl-3H-indolium fragment in position 8 ', were synthesized. The structure of the compounds was carefully studied using NMR, IR and mass spectroscopy, as well as SC XRD. Studies on absorption and photoluminescence characteristics, as well as photochromic behavior were carried out. image

Using the reaction of 2,4-di-(tert-butyl)-12-(4-methoxyphenyl)-10-methoxy-12H-quinoxalino[2,3-b]phenoxazine with π-electron acceptors such as tetracyanoquinodimethane and 3,6-di-(tert-butyl)-o-quinone) as an example it was shown that derivatives of this N,O-pentaheterocyclic system are effective electron donors that, under mild conditions, carry out electron transfer reactions with the formation of stable cation and anion radical structures.

A series of new derivatives comprising heteropentacyclic 12 H -quinoxalino[2,3- b ]-phenoxazine (QOPO) system and functionalized with arylamide anchoring groups was synthesized. Their photostability as well as the spectral, luminescent, electrochemical, and optoelectronic properties were studied both in composites prepared by adsorption of QOPO onto the TiO 2 surface and in solution. Attachment of the amide anchoring groups to the QOPO core provides high adsorption of the compounds and the onset of photovoltaic properties that were not observed in the unfunctionalized precursors. However, these groups do not provide efficient injection of excited electrons into the conduction band of the semiconductor. According to B3LYP/6-311++G(d,p) density functional calculations of the model nanoclusters QOPO/(TiO 2 ) 10 , efficient electron injection and, as a consequence, high photovoltaic conversion efficiency of dye-sensitized solar cells require delocalization of the LUMO of the QOPO/TiO 2 system over both structural fragments. Relevant anchoring groups are proposed.

Spiropyrans modified with reactive polyfunctional substituents are of great interest as building blocks for the creation of various smart systems with controllable properties for materials science and biomedicine. In this study, a new highly modified spiropyran of the indoline series, methyl 5′-chloro-8-formyl-5-hydroxy-1′,3′,3′-trimethyl-spiro[chromene-2,2′-indoline]-6-carboxylate, was obtained via the cyclocondensation reaction from 5-chloro-1,2,3,3-tetramethyl-3H-indolium perchlorate and methyl 3,5-diformyl-2,4-dihydroxy-benzoate. The molecular structure of the target compound was confirmed by 1H, 13C NMR, and IR spectroscopy, as well as LC/MS and elemental analysis. Photochemical studies revealed photochromic activity for the obtained spiropyran at room temperature. The photoinduced merocyanine form demonstrated an enhanced lifetime and fluorescent properties in the red region of the spectrum.

The introduction of a switchable function into the structure of a bioactive compound can endow it with unique capabilities for regulating biological activity under the influence of various types of external stimuli, which makes such hybrid compounds promising objects for photopharmacology, targeted drug delivery and bio-imaging. This work is devoted to the synthesis and study of new spirocyclic derivatives of important human hormones—β-estradiol and estrone—possessing a wide range of biological activities. The obtained hybrid compounds represent an indoline spiropyrans family, a widely known class of organic photochromic compounds. The structure of the compounds was confirmed by 1H and 13C NMR, IR, HRMS and single-crystal X-ray analysis. The intermolecular interactions in the crystals of spiropyran (3) were defined by Hirshfeld surfaces and 2D fingerprint plots, which were successfully acquired from CrystalExplorer (v21.5). All target hybrids demonstrated pronounced activity in the visible region of the spectrum. The mechanisms of thermal isomerization processes of spiropyrans and their protonated merocyanine forms were studied by DFT methods, which revealed the energetic advantage of the protonation process with the formation of a β-cisoid CCCH conformer at the first stage and its further isomerization to more stable β-transoid forms. The proposed mechanism of acidochromic transformation was confirmed by the additional NMR study data that allowed for the detecting of the intermediate CCCH isomer. The study of the short-term cytotoxicity of new spirocyclic derivatives of estrogens and their 2-formyl-precursors was performed on the HeLa cell model. The precursors and spiropyrans differed in toxicity, suggesting their variable applicability in novel anti-cancer technologies.

A convenient method for the synthesis of a series of 2-arylamino-3H-phenoxazin-3-ones based on the nucleophilic substitution reaction between sterically crowded 3H-phenoxazin-3-one and arylamines performed by short-term heating of the melted reactants at 230-250 °C is described and the compounds are characterized by means of single-crystal X-ray crystallography, NMR, UV/vis, IR spectroscopy and cyclic voltammetry. Involvement into the reaction of arylamines with o -amino-, o -hydroxy and o -mercapto-substituents widens its scope and provides for an access to derivatives of N,O- and N,S-heteropentacyclic quinoxalinophenoxazine, triphenodioxazine and oxazinophenothiazine systems.

This study focuses on the molecular design and synthesis of salt spiropyrans with near-IR fluorescence. The structure of the obtained compounds was confirmed by NMR, IR and mass spectroscopy. In the course of studying the spectral and photoluminescent characteristics, it was possible to reveal the effect of some substituents in various positions on the properties of spiropyran dyes. Due to the structural similarity of one of the isomers to cyanine dyes, the obtained compounds are of interest as potential fluorescent probes for bioimagimg, in particular, for DNA studies. To reveal their ability of binding to DNA molecules molecular docking was carried out. Toxic effects of compounds demonstrating NIR fluorescence were studied on biofilms, as well as using bacterial lux-biosensors.

This article is devoted to a detailed study of structural features of spiropyrans of the 1,3-benzoxazine-4-one series with various substituents in the 6 ' position of the 2H-chromene moiety using single crystal X-ray diffraction analysis, as well as IR and NMR spectroscopy, including various two-dimensional NMR techniques. Intermolecular interactions and cavities in crystals of compounds were studied using the CrystalExplorer 21.5 software package. Spectral-kinetic studies of the obtained compounds revealed the presence of photochromic properties for nitro-substituted spiropyran. The mechanism of isomerization transformations of target compounds was studied using quantum-chemical calculations based on DFT methods. The calculation results made it possible to determine the most energetically favorable merocyanine conformers of spiropyrans and helped to explain the observed photochromic activity. (c) 2023 Elsevier B.V. All rights reserved.

The reaction between 3,5-di(tert-butyl)-o-benzoquinone 1 and o-phenylenediamine performed under oxidative conditions that is highly sensitive to the reaction conditions (type of solvent, ratio of reactants, and duration of the reaction) gives rise to various derivatives of a new condensed 10H-quinoxalino[3,2,1-kl]phenoxazin-10-one heteropentacyclic system. The reaction of 1 with N-phenyl-o-phenylenediamine results in the formation of three phenazine-like compounds and, unexpectedly, a derivative of a new spiro[1,3]dioxole-2,2'-furanyl-1H-benzo[d]imidazole system. The molecular structures of the prepared compounds were authenticated by NMR, mass spectra and X-ray crystallography data.

New indoline spiropyrans containing chlorine and bromine atoms in position 5 of the indoline moiety of the molecule as a substituent were synthesized and studied. The structures of the synthesized compounds were confirmed by NMR and IR spectroscopy. The molecular structure of the chlorine-substituted derivative was determined by X-ray diffraction analysis, and intermolecular interactions in the crystal were studied using the CrystalExplorer21.5 software package. The spectral kinetic studies revealed photochromic properties of novel spiropyrans in an acetonitrile solution. The photoelectrochemical characteristics of dye-sensitized solar cells (DSSC) made from the synthesized compounds before and after UV irradiation were studied in comparison.