Novel azine-fused [6]helicenes were prepared in five synthetic steps starting from commercially available 2,3-dihaloazines (2,3-dibromopyridine, 2,3-dichloropyrazine and 2,3-dichloroquinoxaline). The X-ray structures, UV-vis absorption and fluorescence spectra of the helicenes were investigated and compared to those of the parent [6]carbohelicene. It was shown that pyrazine-fused [6]helicenes, bearing a pyren-1-yl or 1,8-bis(dimethylamino)naphthalen-4-yl side substituent, contain both helical and axial stereogenic elements and exist as a mixture of stable (P,Sa)-, (M,Ra)-, (P,Ra)- and (M,Sa)-isomers at room temperature. The barriers to R/S- and P/M-isomerizations, as well as the relative stabilities of the isomers, were estimated theoretically.

6-Bromo- and 6,7-dibromo-1,3-dimethyl-1H-perimidin-2(3H)-ones were arylated with arylboronic acids under Suzuki-Miyaura reaction conditions to afford 6-aryl-, 6-bromo-7-aryl- and 6,7-diaryl-1,3-dimethyl-1H-perimidin-2(3H)-ones. A comparison of the X-ray structural parameters of peri-diaryl derivatives of 1,3-dimethyl-1H-perimidin-2(3H)-one, naphthalene and 1,8-bis(dimethylamino)naphthalene (proton sponge) was performed. Based on the data of dynamic 1H NMR spectroscopy and quantum-chemical calculations, barriers to syn/anti-isomerization of 6,7-diaryl-1,3-dimethyl-1H-perimidin-2(3H)-ones were estimated. The optical properties of 6-aryl- and 6,7-diaryl-1,3-dimethyl-1H-perimidin-2(3H)-ones as structural analogs of fluorophoric 6-aryl- and 6,7-diaryl-1,8-naphthalimides were studied.

Nanomaterials based on metal oxides are promising catalysts for photocatalytic water purification. To increase the efficiency of water purification, modifying additives are introduced into the nanomaterials as well as the synthesis conditions are varied. In this work the photocatalytic activity of pristine TiO2 and La-doped TiO2 nanomaterials have been investigated for the methylene blue dye degradation. La-doped TiO2 nanoparticles were obtained by a simple chemical method in solution. The influence of synthesis conditions and La3+ content (0.5–5 mol.

The reaction of 12H-quinoxaline[2,3-b]phenoxazine (QOPO) with lanthanide hexafluoroacetylacetonates is accompanied by protonation of the QOPO and leads to the formation of salts of the general formula [QOPOH]+[Ln(hfac)4]- (Ln = Nd, Dy, Tb, Ho), whose structures have been determined by X-ray diffraction analysis and 1H NMR spectroscopy. The compounds are characterized by long wavelength absorption and fluorescence (lambda fl = 677-740 nm). The study of the magnetic properties of the complexes has revealed that the Tb complex exhibits slow magnetic relaxation under an applied dc field, while the Dy complex behaves as single-ion magnet (SIM) even at zero field. These two compounds are the first examples of anionic complexes based on Dy and Tb ions coordinated by four hexafluoroacetylacetonates that exhibit the SIM properties under zero and applied dc fields, respectively.

Novel double aza- and diaza[4,5]helicenes, the two helical units of which have a common naphthalene core, have been prepared through a five-step synthetic sequence using commercially available 2,3-dihaloazines (2,3-dibromopyridine, 2,3-dichloropyrazine and 2,3-dichloroquinoxaline) as starting materials. The X-ray structures, UV-vis absorption and fluorescence spectra of the helicenes were investigated and compared to those of the parent phenanthrene, single aza[4]- and [5]carbohelicenes, and a double [4,5]carbohelicene.

Chromo-fluorogenic phenomena, well investigated in certain phase states of a substance, become a subject of interest for studying the possibility of their manifestation in several phase states, as well as during the transition from one phase state to another. Synthesis methods have been developed and several derivatives of 6-nitro(formyl)-8-formyl(nitro)spirobenzopyran-indoline have been obtained, which is a molecular platform that makes it possible to realise a number of unique properties, including the barochromic effect in the gas phase, dual-state photochromism, dual-state photochromic cycle and highly efficient fluorescent molecular switches in solution. When studying the barochromic effect, the criteria for a molecular platform that determine the possibility of its manifestation were determined.

Molecular platforms, capable of exhibiting various well-known properties, allow us to observe under certain structural modifications, due to the combination of these properties, the formation of new effects or phenomena, for example, photochromic balance. The 6-bromo-substituted spiro[indoline-pyranoquinolines] were found to exhibit the properties of photochromic balance, exhibiting both positive and negative T-type photochromism. A detailed study was carried out on the thermodynamics and kinetics of processes, the combination of which forms the effect of photochromic scales: the equilibrium of cyclic and merocyanine isomers of spiropyrans, thermal opening of the pyran ring and thermal recyclisation, and photocolouring and photobleaching of spiropyran solutions. Based on experimental data and quantum chemical modelling, directions for structural tuning have been established for the most pronounced manifestation of the effect of photochromic balances based on spiro[indoline-pyranoquinolines], which include enhancing the electron-withdrawing properties of the substituents in the pyridobenzopyran part of spiropyrans and the introduction of strong electron-donating groups into the indoline fragment.

4-Bromo- and 4,5-dibromo-1,8-bis(dimethylamino)naphthalenes were arylated with arylboronic acids under Suzuki reaction conditions to provide 4-aryl- and 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes, respectively. The interaction of 4,5-dibromo-1,8-bis(dimethylamino)naphthalene with pyridin-3-ylboronic acid was accompanied by heterocyclization leading unexpectedly to the formation of N3,N3,N4,N4-tetramethylacenaphtho[1,2-b]pyridine-3,4-diamine. Dynamic 1H NMR experiments showed fast interconversion between syn and anti conformers of 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes in CDCl3 solution at room temperature. The free energy of the rotational isomerization was determined to be ∼14.0 kcal mol-1 for 4,5-di(m-tolyl) and 4,5-di(naphthalen-2-yl) derivatives. X-ray analysis of 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes revealed a high degree of structural deformation due to internal steric repulsions between both peri-dimethylamino and peri-aryl groups. In crystals, 4,5-di(naphthalen-1-yl)-1,8-bis(dimethylamino)naphthalene molecules exist exclusively in the most stable anti-out form, while for 4,5-di(naphthalen-2-yl) and 4,5-di(m-tolyl) counterparts, only the syn-form is realized. The introduction of two peri-aryl substituents in the 1,8-bis(dimethylamino)naphthalene scaffold affected the basic properties, making the 4,5-diphenyl derivative 0.7 pKa units less basic. The protonation of 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes leads to dramatic changes in their structures. Compared to the corresponding bases, the inter-nitrogen distance in these salts noticeably decreases whereas peri-aromatic rings move away from each other demonstrating the so-called "clothespin effect". This lowers the barriers of syn/anti-isomerization; as a result, protonated molecules with peri-m-tolyl and even peri-(naphthalen-2-yl) substituents exist in crystals as mixtures of rotamers.

A promising spiro[pyridobenzopyran–indoline] molecular platform for the development of ionochromic systems with a high potential for metal cation chemosensor applications is developed. Evidence for this conclusion is provided the established characteristics and properties of 6-bromo-substituted spiro[pyridobenzopyran–indoline], including ionochromism accompanied by a chromogenic effect in the form of a red shift that reaches 200 nm. The obtained Zn(II), Ni(II), Cu(II), Co(II), and Cd(II) complexes are characterized by a high stability with constants of 10 5.6 –10 8.6 and 10 5.0 –10 6.9 for the first and second steps, respectively. The possibilities to obtain selective sensors are associated with the fluorescence detected in the Zn(II) and Cd(II) complexes only. The photostability of the studied complexes, on the one hand, and the high spectral contrast of complex formation of the dynamic 6-bromo-substituted spiro[pyridobenzopyran–indoline] systems on the other, open up the possibility of using chemosensors based on these molecular platforms in the naked-eye colorimetric mode.

Nanocrystalline Al-ZnO films were successfully synthesized by thermal decomposition method. The method includes two stages: synthesis from the melt of organic salts and the films production. The effect of the calcination temperature varying from 600 to 800 °C on the crystallite sizes, phase composition and optical properties of the synthesized films was also investigated. X-ray diffraction (XRD) showed the formation of a hexagonal wurtzite crystal structure with a distorted lattice upon the introduction of Al 3+ ions. Based on calculations and scanning electron microscopy (SEM) images, the crystallites size increased from 18 to 28 nm with the calcination temperature increasing. Optical properties of Al-ZnO films were studied by optical transmission spectra. An increase in the calcination temperature leads to a decrease in the ZnO band gap. It was shown that the proposed method makes it possible to obtain optically transparent Al-ZnO films consisting of nanocrystallites. By varying the calcination temperature, the optical properties can be adjusted, which will significantly expand the application range of these materials.

Effect of the anion nature on crystal structure of Zn-complexes of spironaphthopyran and their chromogenic properties in solution were studied. Complexes with zinc chloride and zinc picrate exhibited tertahedral and octahedral coordination environment of the metal ion respectively. The structure of the complex with zinc picrate demonstrates a rare example of the co-crystallization of two types of complexes differing in the number of coordinated picrate anions. The composition, stability, and absorption properties of zinc complexes in acetone essentially depend on the counter anion nature. When the coordinating ability of the counter ion increases in the range BF4- , ClO4- , NO3-, Pic-, I-, Cl-, CH3COO-, (CH3)3CCOO- the complex stability is reduced from logK = 8.7 to 2.96. This is accompanied by the chromogenic effect which is related to the decrease in the spectral shift of the long-wavelength absorption band of the complex relative to the merocyanine ligand from 846 up to 168 cm-1. The complex photo-initiated processes include fluorescence and thermally reversible dissociation. Fluorescence is characterized by band maxima in the 622-637 nm region and normal Stokes shifts of 1087-1454 cm-1 with an efficiency being weakly dependent on the anion nature. In contrast, the negative photochromism of the complexes demonstrates a significant dependence of the photo-bleaching efficiency on the anion nature in the range 0.012-0.17. The presence of a chromogenic photochromic effect along with fluorescence makes it possible to consider the complex as fluorescent switch.

Spiropyranindoline derivatives bearing an ortho-hydroxyphenylbenzimidazole moiety were synthesised. The spiropyran cyclic isomers possessed dual-state emission properties. Fluorescence exhibiting an anomalous Stokes shift, due to proton transfer in an excited state, was characterised by a high efficiency with quantum yields of 0.2–0.4 both in solution and in solid-state samples. In solution, the spiropyrans manifested a thermally and photochemically reversible coloration with quantum yields reaching 0.66. The unusual dual-state photochromic cycle of the spiropyrans involved an irreversible photo-staining in the solid state followed by thermal bleaching in solution. The combination of fluorescence and photochromic properties allow spiropyranindoline derivatives bearing an ortho-hydroxyphenylbenzimidazole moiety to be considered as fluorescent molecular switches.

A novel photochromic system based on an alkylideneisochromanedione core with heterocyclic substituents was synthesized, and its spectral luminescent and photoinduced properties were studied. The obtained iso-chromandiones containing the hexatriene fragment exist in a ring-open E-form, confirmed by the data of H-1, C-13 NMR spectroscopy and X-ray diffraction studies. The observed photoinitiated processes depend fundamentally on the nature of the heterocyclic substituents. Thiophenyl, benzo[b]thiophenyl and 1H-indolyl derivatives 5c-f are non-photochromic in the solid state, and in solutions their transformations are limited by thermally reversible E/Z-photoisomerization. Compound 5a with a furanyl substituent is photochromic in crystalline form due to the light-induced rearrangement of the ring-open hexatriene isomer into the ring-closed cyclohexadiene structure. Upon irradiation with light of 436 nm, the yellow crystals of 5a turn dark blue-green. The reverse reaction of the cycle opening and restoration of the original color of the crystals occurs extremely easily upon irradiation with visible light of 578 nm. In contrast to crystals, solutions of compounds 5a and 5b with furanyl substituents in hexane, 2-propanol, acetonitrile and DMSO are discolored when irradiated with light of 365 nm. The irreversible photorearrangement 5a,b -> 6a,b includes the stages of cyclization, the opening of the furan cycle and the formation of highly fluorescent naphthalic anhydride derivatives 6 (the quantum yield of fluorescence reaches 0.69 in hexane)), which can be used for the production of optical memory media for archive 3D discs.

A compound of the new spirobipyran-quinoline series possesses weakly pronounced photochromic properties at room temperature. Its interaction with Co2+, Ni2+, Zn2+ and Cd2+ ions leads to intensely colored complexes absorbing in the λ> 600 nm region, which is important for the study of biological objects. Up to three merocyanine molecules are capable of binding one metal ion, which is not typical for the previously studied indoline analogs.

Thin TiO2-films were synthesized for the first time by solid-phase low-temperature pyrolysis technique onto quartz glasses or silicon substrates. The obtained films are nanoscale; crystallize in a mixed anatase-rutile modification, which was confirmed by X-ray diffraction, scanning electron and atomic force microscopy (AFM) methods. The three-layer films’ thickness was 140 nm. The TiO2-films consist of crystallites 12–27 nm, depending on the temperature treatment and phase composition. In addition, all of the obtained TiO2-films are optically transparent regardless of synthesis conditions; the calculated band gap was 3.55 eV, which makes it possible to recommend TiO2-films for use in optical filters and gas sensors.

A spiroindolinonaphthopyran of the diphenyloxazole series along with photochromism possesses a number of chromogenic properties such as solvatochromism, ionochromism, solid state phasochromism and fluorescence. The nature of these effects is associated both with the possibility of the spiropyran existence under its two forms (cyclic and merocyanine) and with the peculiarities of the molecular structure, in particular, with the presence of a diphenyloxazole fragment. Photo -chromic properties of the spiroindolinonaphthopyran do not exhibit a drastic dependence on the nature of solvents, including those that are capable of specific intermolecular hydrogen bond interactions. In addition, good resistance to photodegradation in the mode of photochromic balance opens up possibilities for designing polychromogenic molecular systems based on them. The positive solvatochromism of the first type, which is noticeably manifested in the case of mer-ocyanine isomers, allowed establishing the weak polarity of their ground state. Solvatochromism of the second type demonstrates a significant spectral contrast (up to 227 nm) due to the existence of an equilibrium of cyclic and merocyanine isomers. The intensity of the effect increases upon passing from toluene to DMSO due to the shift of the equilibrium towards the merocyanine isomers. The presence of a chelate center formed by the merocyanine oxygen atom and the nitrogen atom of the diphenyloxazole fragment allows observing ionochromic transformations of the spiropyran molecule associated with the formation of coloured complex compounds upon its interaction with Co, Cu, Ni, Zn, Cd, Mn ions. It has been established that solutions of Zn, Cd, and Mn complexes exhibit the negative photochromism properties. The change in the solid state of spirpyran is accompanied by a change in the ability to undergo photochromic transformations. Under standard conditions the spiropyran exhibits photochromic properties in the crystalline state, but not in the amorphous one. The combination of chromogenic properties makes it possible to implement fluorescent molecular switches, bipolar absorption switches, photodynamic chemosensors, and solid-state phase transitions control the chromogenic properties based on spiropyrans of diphenyloxazole series. The possibility of structural modification leading to an enhancement of some properties and/or a weakening of other ones makes it possible to consider a spiroindolinonaphthopyran of a diphenyloxazole series as a molecular platform for creating polychromogenic molecular systems with desired properties.

The reaction of fluorescein-substituted 2-hydroxybenzaldehyde with 3H-indolium perchlorate has led to the formation of 1,3-dihydrospiro[indole-2,2′-chromene] bearing a fluorescein fragment at position 8 of chromene. In a solution, the obtained compound has existed in the cyclic form and has exhibited photochromic properties. Adding transition metal perchlorates to the spiropyran solution has led to intense coloration due to the complex formation. Zinc and cadmium complexes of the spiropyran have exhibited red fluorescence and negative photochromism.

Synthesis and magnetic characterization of a family of cobalt-dioxolene complexes [(Me2TPA)Co(36-DBCat)] (1), [(Me2TPA)Co(36-DBCat)](PF6) (2) and [(Me2TPA)Co(diox-(OMe)3)](BPh4) (3) (Me2TPA = bis(6-methyl-2-pyridyl)methyl-(2-pyridylmethyl)amine; 36-DBCat = dianion of 3,6-di-tert-butylcatechol; diox-(OMe)3 - 2,5-di-tert-butyl-3,3,4-trimethoxy-6-oxocyclohexa-1,4-dienolate) is reported. The neutral complex 1 is found to form hexa- (CoO2N4, 1a) and pentacoordinated (CoO2N3, 1b) isomers. Variable temperature single crystal X-ray diffraction analysis of 1a and 1b clearly indicates the presence of the high-spin divalent metal ion and the dianionic catecholate form of the dioxolene ligand. Oxidation of 1 by ferrocenium hexafluorophosphate results in the formation of the ionic octahedral complex 2, demonstrating thermally induced valence-tautomeric transition (ls-CoIII-36-DBCat ⇄ hs-CoII-36-DBSQ) in the solid state with T1/2 = 175 K (36-DBSQ = radical-anionic semiquinonate form of the redox-ligand). In contrast, aerial oxidation of 1 is accompanied by changes in the structure of dioxolene resulting in oxocyclohexadienolate ligand and the formation of an ionic complex of high-spin divalent cobalt (3). Compounds 1a, 1b, and 3 are found to demonstrate a field-induced single-ion magnet behavior. The analysis of the electronic structures of 1, 2 and 3 with the aid of DFT and SA-CASSCF/NEVPT2 calculations is also given.

Sulfur-containing amino acids play an essential role in the physiological process. Spiropyrans are a class of photochromic substances, which can be used for the determination of sulfur-containing amino acids and oligopeptides, such as cysteine, methionine, glutathione. Herein we used spiropyran 5,6′-dichloro-1,3,3-trimethylspiro[indoline-2,2′-2H-pyrano[3,2-h]quinoline] (DTIQ) for analytes sensing. DTIQ demonstrates a selective response toward glutathione in the presence of cysteine and methionine. It allows us to develop simple, rapid and sensible methods of spectrophotometric and fluorimetric glutathione assay. The developed methods were applied to quantification of glutathione in the dietary supplement and human urine. At the same time, DTIQ was found to bind Cu2+ with the formation of complex, which can be destroyed by glutathione or cysteine. Since that is accompanied by absorption changes, DTIQ application as a glutathione and cysteine “ON–OFF-ON” sensor is possible. The elaborated methods are characterized by low limits of detection, which are quite enough to quantify analytes at the level of their physiological concentration.