A series of previously unknown coumarin-rhodamine derivatives was synthesized. The resulting compounds exhibit long-wavelength absorption in the range of 408–443 nm in acetonitrile. However, the presence of a methyl group in the bridge connecting the coumarin and rhodamine fragments of the molecule leads to a hypsochromic shift to 310 nm due to a steric effect that weakens conjugation. The obtained compounds exist in the cyclic spirolactam form, which is further confirmed by the absence of fluorescence above 520 nm. The ionochromic and sensory properties of coumarin-rhodamines were studied in the presence of d-metal cations in acetonitrile solutions. A highly selective interaction of the obtained compounds with Hg2+ cations was discovered, accompanied by the appearance of a characteristic red color due to the appearance of new absorption maxima in the region of 560 nm, as well as the appearance of intense fluorescence at 580-584 nm. This spectral response is due to the cation-induced opening of the spirolactam ring. Furthermore, the addition of cyanide ions (CN⁻) to the in situ formed Hg2+ complexes initiates a selective reverse isomerization back to the non-fluorescent spirolactam form, effectively restoring the original spectral characteristics. The described transformations can be repeated at least 4-5 times, which ensures effective modulation of the emission properties. To facilitate practical applications, test strips impregnated with the coumarin-rhodamine hybrids were developed, enabling rapid, real time and instrument-free detection of Hg2+ ions. Thus, coumarin-rhodamine derivatives can be used as effective molecular switches of optical properties, as well as in the production of materials for monitoring the composition of the environment. For citation: Dubonosov A.D., Nikolaeva O.G., Popov L.D., Shepelenko Е.N., Dubonosova I.V., Bren V.A. Synthesis, ionochromic properties of coumarin-rhodamine derivatives and their application in test strips. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2026. V. 69. N 8. P. 25-32. DOI: 10.6060/ivkkt.20266908.7005.

New vitamin E hydrazone analogues bearing (2-hydroxyaryl) methylene moieties were obtained from Trolox hydrazide and the corresponding 2-hydroxyarenecarbaldehydes. The compounds demonstrated effective antioxidant activity and selective action against cancer cells, suggesting their potential as supportive pharmacological agents in oncology.

Generally, the intermolecular H-bonding is a powerful type of interactions capable of playing dominating role in the self-assembly of extended molecular networks in the crystalline phase. Herein, we report on the first example of 1D supramolecular polymerization, supported by the intermolecular H-bonding involving the 3,5-dihalogenosalicylideneamine moieties, appended to 1.3-disubstituted calix[4]arene platform, and imposed exclusively by the crystal packing effect, which was elucidated primary by the X-ray diffraction study.

The reaction of 4-nitro-N'-(pyridin-2-ylmethylene)benzohydrazide (HL) with Ln (OAc)(3)4H(2)O in MeOH makes it possible to synthesize mononuclear complexes [Ln(L)(2)(OAc) (MeOH)]center dot 2H(2)O (Ln = Tb-III (1), Eu-III (2) and Gd-III (3)) with chelate acetate and L- anions. Compound 1 can be crystallized in reaction with molar ratio HL:Ln = 1:1, 2:1, 3:1, and we successfully synthesized complex with three chelate L anions [Tb(L)(3)](2)2MeOH center dot H2O (4) by interaction of TbCl3 center dot 6H(2)O with deprotonated HL (HL:Ln = 3:1). Terbium (III) compound 1 starts to decompose at similar to 323 K and becomes stable up to 552 K according to the STA. Compound 1 shows slow magnetic relaxation with parameters Delta(eff)/k(B) = (6.75 +/- 0.02) K, tau(0) = (1.71 x 10(-6)+/- 1 x 10(-8)) s. Complexes 1 and 2 exhibit only fluorescence and phosphorescence of the L-. Ion-centered luminescence of the Tb3+ or Eu3+ ion is not observed. Using the tangent method at the high-energy edge of the phosphorescence spectrum of Gd3+, complex 3 T-1 energy level of L- is estimated to be 19700 cm(-1). Reasons of luminescence quenching are discussed. Structures of 1 and 4 were determined by single crystal X-ray diffraction, and compounds 1-3 were characterized by powder X-ray diffraction (PXRD).

A series of copper(II), nickel(II), and cadmium(II) compounds with pivalate (Piv) or pentafluorobenzoate (Pfb) anions and 2-amino-1-methylbenzimidazole (L) molecules, [Cu2(Piv)4(L)2]·2MeCN (I), [Ni(Piv)2(L)2][Ni(Piv)2(L)2(MeOH)] (II), and [Cd(Pfb)2(L)2] (III), were obtained. In the case of copper compounds, a binuclear complex with a Chinese lantern structure was formed, while nickel and cadmium salts resulted in the formation of mononuclear complexes. In all synthesized compounds, the 2-amino-1-methylbenzimidazole molecule is a monodentate ligand, coordinated to the metal atom via the nitrogen atom of the benzimidazole ring. The compounds were characterized by X-ray diffraction, IR spectroscopy, and CHN analysis.

The structure of representatives of a new heterocyclic system, 12H-benzimidazo[1',2':1,6]pyrido[2,3-b]indole-6-carbonitriles, potential bioactive compounds, is elucidated by X-ray diffraction. The compounds exhibit luminescence in the blue region of the spectrum with quantum yields close to unity, which makes them promising phosphors for application in modern emitting devices.

Eu(III) compounds with pyrazine-2-carboxylic acid and nitrogen- and phosphorus-containing neutral ligands were synthesized. Using the methods of chemical elemental and thermal analysis and IR spectroscopy, the composition of the complexes and the method of coordination of carboxylate ions were established. The most thermally stable compounds have been identified. The luminescent characteristics of complex compounds have been studied. It was found that the maximum luminescence intensity is characteristic of europium(III) pyrazinate with triphenylphosphine oxide. The morphological structure and dispersion of the complexes were determined.

The reaction of the bicyclic polyfunctional electrophilic system – 1-ethoxy-5-methyl-3,8-diphenyl-1H-pyrano[3,4-c]pyran-7-ium perchlorate with heterocyclic and aromatic acid hydrazides leads to the corresponding N-aminopyridinium ylides in one-pot. The reaction conditions have been optimized and a mechanism for the formation of the ylides has been proposed.

Bifunctional hybrids of a new type containing photochromic indolyl(thienyl) diarylethenes with a pyrroldione bridge directly linked by a dimethylene spacer to an ionochromic rhodamine moiety were synthesized. The synthesized hybrids in toluene exhibit absorption at 450-455 nm and fluorescence at 560 nm. Irradiation with UV light leads to the formation of ring-closed non-fluorescent diarylethene isomeric fragments. Under visible light (or gradually in the dark conditions), reverse isomerization to the initial forms occurs. The spectral and kinetic characteristics of the processes have been studied. In the presence of H+ cation, a striking naked eye effect is observed due to the opening of the rhodamine-spirolactam ring and appearance of a characteristic pink-crimson coloration at 561 nm along with intense long-wavelength emission at 586 nm. This process is completely reversible upon exposure to triethylamine. The mechanism of this transformation was confirmed by additional 1H and 13C NMR experiments. The M06-2X/Def2-TZVP method and AIM analysis were successfully used to explain observed light-induced isomerizations as well as proton-induced transformations. Thus, revers-ible switching of the fluorescent properties of hybrid molecules can be operated by light irradiation and proton.

Mononuclear nickel complexes [NiL1(NCS)2]·2DMSO (I), [NiL1(NCS)2]·DMF (II), and [NiL2(NCS)2]·0.5CH3OH·1.5H2O (III) with the distorted octahedral coordination node, where L1 and L2 are the tetradentate ligand systems derived from the products of the condensation of diacetyl with 2-hydrazinoquinoline and 2-hydrazino-4,6-dimethylpyrimidine, respectively, are synthesized. The structures of the compounds are determined by IR spectroscopy and XRD (CIF files ССDС nos. 2219793 (I), 2142035 (II), and 2219794 (III)). The quantum chemical modeling of the axial parameter of magnetic anisotropy in the zero field (D) is performed for the synthesized compounds in the framework of the SA-CASSCF+NEVPT2 method. The complexes are shown to be characterized by three-axis magnetic anisotropy close to the light magnetization plane with positive D. The axial parameter of magnetic anisotropy (Dexp = 8.79 cm−1) determined by the approximation of the magnetometry data on complex [NiL2(NCS)2]·0.5CH3OH·1.5H2O is consistent with the calculated value (Dcalc = 11.5 cm−1).

A simple and accessible method has been developed for the preparation of copper-containing nanocomposites by thermolysis of a copper(II) complex with a Schiff base based on 3-formyl-4-hydroxycoumarin and octadecylamine at 500 degrees C. The resulting nanoparticles with a particle size of up to 85 nm were used as additives to lubricants. It has been established that copper oxide nanoparticles with a concentration of 0.5 % and 1 % increase the anti-wear and anti-friction properties of the lubricant. image

5-(2-Hydroxyphenyl)-3-methyl-1-(quinolin-2-yl)-1H-1,2,4-triazole (L), its O-ethyl derivative, and the L2Be(II) complex have been synthesized. It has been found that the complex with Be(II) fluoresces intensely with φ = 0.37–0.42 in the blue region of the visible spectrum (λflmax 450–456 nm), whereas ligand (L) and its O-ethyl derivative emit light with a low quantum yield because of the ESIPT process and conformational non-rigidity, respectively. The alternative structures of ligand (L), its O-ethyl derivative, L2Be(II) complex, and their most energetically stable conformers and isomers were found by calculation using the CAM-B3LYP/6-311++G(d,p) method.

Reaction of a series of 2,6-diacetylpyridine bis-hydrazones with copper(II) chloride and bromide yielded pentacoordinated complexes exhibiting high cytotoxic activity.

The photochemical and photophysical properties of the new ligand N-[2-(5,6-dihydrobenzimidazo[1,2-c]quinazoline-6-yl)phenyl]-4-methylbenzolsulfamide (1) and its zinc complexes, namely [2-[(E)-[2-(1H-benzimidazol-2-yl)phenyl]iminomethyl]-N-(p-tolylsulfonyl)anilino]chloro-zinc (3) and acetoxy-[2-[(E)-[2-(1H-benzimidazol-2-yl)phenyl]iminomethyl]-N-(p-tolylsulfonyl)anilino]zinc (4) were studied using UV spectroscopy, time-resolved luminescence and stationary photolysis. Compound 1 combines the properties of Schiff bases and benzimidazole derivatives, both known as good luminophores. The structures of compounds in the crystalline state were determined by means of XRD. Ligand 1 demonstrates high photoluminescence quantum yields (PLQY) in solutions, while for the soluble zinc complex 3 it drops in an order of magnitude. PLQY in the solid state for all the compounds are moderate (0.2–0.3). For complex 3 the PLQY in the solid state is ca. 3 times higher than in solutions, demonstrating the effect of aggregation-induced enhancement of luminescence. The approach based on combining properties of the two classes of luminophores seems prospective for further development of luminescent materials.

By the condensation of 4-amino-5-R-2,4-dihydro-3H-1,2,4-triazole-3-thiones with anthracene-9- carbaldehyde, respective 4-[(anthracene-9′-ylmethylene)amine)]-5-R-2,4-dihydro-3H-1,2,4-triazole-3-thiones are prepared and structurally characterized by NMR, UV, IR spectroscopies, high-resolution mass spectrometry, and single crystal XRD. The effect of a substituent at position 5 in triazole moieties of azomethines obtained on their head-to-head or head-to-tail crystal packings is determined.

Конденсацией 4-амино-5-R-2,4-дигидро-3H-1,2,4-триазол-3-тионов с антрацен-9-карбальдегидом были получены соответствующие 4-[(антрацен-9‵-илметилен)амин)]-5-R-2,4-дигидро-3H-1,2,4-триазол-3-тионы, которые структурно охарактеризованы с привлечением методов спектроскопии ЯМР, УФ, ИК, масс спектрометрии высокого разрешения и РСА. Установлено влияние заместителя в положении 5 триазольного фрагмента полученных азометинов на их кристаллическую упаковку «голова к голове» или «голова к хвосту».

Spectral-kinetic and fluorescence properties of hybrid compound, whose molecule includes the photochromic spiropyran fragment and two fluorophores—coumarin and salicylideneimine, were studied in comparison with model compounds—7-hydroxy-4-methylcoumarin, spiropyran of coumarin type and azomethinocoumarin in mixed toluene–acetonitrile solution in the presence of Tb3+ ions. It was shown that the hybrid compound exhibited direct photochromic transformations. Different fluorescence of complexes of the initial spirocycle and UV irradiation-induced merocyanine forms were observed. One green fluorescence emission with a maximum at 570 nm was observed for the initial closed form in mixed solvent solution and the additional red emission of the open merocyanine form in the region of 640 nm appeared after UV irradiation. The merocyanine form fluorescence in the presence of Tb3+ ions extremely increased after irradiation with visible light.

A new bis-benzoxazolylhydrazone of 2,6-diacetylpyridine and mononuclear Cu( ii ) complexes based on it have been synthesized. An in vitro study showed that all Cu( ii ) complexes exhibit high cytotoxic activity against the HepG2 cancer cell line.

In order to study the effect of the dimethylpyrimine fragment nature on the structure and magnetic properties of coordination compounds, new binuclear Cu(II) metallochelates were synthesized. The coordination compounds are [Cu2(HL)2(CH3OH)2](ClO4)2 (1) and [Cu2(HL)2(NO3)2] (2), where HL – the monodeprotonated form of 2-hydrazino-4,6-dimethylpyrimidine and diacetylmonoxime condensation product. The structure and properties of complexes were established using elemental analysis, 1H NMR, IR-spectroscopy, magnetochemistry. It was shown that the coordination compounds are diamagnetic at room temperature due to the strong antiferromagnetic exchange interaction between paramagnetic Cu(II) ions: −2J > 1000 cm−1. The data obtained are in a good agreement with the results of quantum chemical calculations (theory level B3LYP/6 311G(d)).