Novel conjugates of rhodamine B with 2-chloro-, 2-chloro-6-methyl-and 2-chloro-6-methoxyquinoline were synthesized. Their structure and ion-induced switching properties were studied using 1 & Ncy;, COSY, 13 & Scy;, HSQC and HMBC NMR, UV-Vis/fluorescence spectroscopy, X-ray diffraction analysis and DFT quantum chemical calculations. The compounds obtained exist in the spirolactam form, which is characterized by the lack of absorption in the region > 500 nm and the absence of emission properties. However, in the presence of Hg2+ cations, they exhibit a selective and contrasting naked eye effect, as a result of which the colorless acetonitrile solution becomes purple. Simultaneously, the appearance of intense emission at 584-588 nm is observed. These changes are due to the opening of the spirocycle, which was confirmed by an additional 1H NMR experiment. The reverse transformation occurs under the action of CN-anions. The observed ion-controlled off-on-off switching of the fluorescence properties was used to develop the logic circuit. For the first time, using PCM/DFT/M06-2X-D3/ Def2-SVP calculations in acetonitrile and AIM analysis, it was shown that the interaction with mercury(II) cations is a multistage process.

New photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophen-3(2H)-ones containing a terpyridine receptor have been synthesized. They absorb in the visible region of the spectrum at 423-426 nm and exhibit emission at 463-468 nm. Their irradiation in acetonitrile with light of 436 nm leads to a multi-stage rearrangement, including Z/E isomerization about the C--C bond, N -> O migration of the acyl group and the formation of non-emissive O-acylated E-isomers, which were isolated preparatively. Their structure was established unambiguously by IR, 1H, 13C NMR spectroscopy and HR mass spectrometry. The reverse thermal reaction with O -> N migration of the acyl group is catalyzed by acid catalysts. N-Acylated compounds in acetonitrile selectively form non-fluorescent complexes with Fe2+ cations, which is accompanied by the naked-eye effect with changing the color from yellow to maroon. A successful selective interaction with AcO- led to the restoration of the initial absorption and emission properties. Density functional theory (DFT) calculations at the M06-2X/def2TZVP level with the PCM solvation method were used to explain the observed photoisomerizations and ionochromic transformations. The obtained compounds represent multifunctional on-off-on molecular switches of optical and fluorescent properties upon sequential exposure to light and H+ or sequential addition of Fe2+ and AcO- ions. A combinatorial logic gate was designed based on the basis of these switching properties.

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.

New coumarinyl(pyrrolyl)ethenes with a 1,3-thiazole bridge were synthesized. When irradiated at 365 nm, a hexatriene-cyclohexadiene rearrangement of the ring-opened form into a colored non-fluorescent ring-closed isomer occurs. The back reaction takes place when exposed to visible light at 540 nm. Furthermore, the compound with terminal 2,4-di-tert-butyl-6-hydroxybenzylidene receptor group represents a multifunctional sensor exhibiting selective chromogenic activity towards palladium(II) ions and CN- and F- anions. This probe interacts with Pd2+ cations with a noticeable naked eye effect - a change in the solution color from yellow to orange. The complexation stoichiometry is 1:1 and the detection limit was found to be 4.5 x 10(-7) mol L-1. Similarly, CN- and F- anions cause a contrast naked eye effect with a change in the color of the solution from yellow to rose-red. For convenient detection of the above ions, test strips containing 4-(2-(2-(2,4-di-tert-butyl-6-hydroxybenzylidene)hydrazinyl)-5-(2-oxo-2H-chromen-3-yl)thiazol-4-yl)-1,5-dimethyl-1H-pyrrole-2-carbonitrile have been developed. In addition, a combinatorial molecular logic gate was designed based on multi-controllable photoswitching properties of the obtained probe.

The reaction of 3-[(amino-2-naphthyl)amino]-5,5-dimethylcyclohex-2-en-1-one with o-quinones provided previously unknown macrolactones of the oxonine series with naphthopyrazine fragments.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Novel diarylethenes with a 1,3-thiazole bridge connected by a hydrazinomethylene spacer with tetrazolo[1,5- a ]quinoline substituents were synthesized. They exhibit photochromic properties in acetonitrile or in a semiaqueous acetonitrile solution when exposed to the 436 nm light, associated with isomerization into a colored ring-closed form. The reverse reaction occurs under irradiation with visible 540 nm light. The compounds obtained demonstrate ionochromic “naked eye” effects in the presence of fluoride anions or nickel(II) and zinc(II) cations due to a change in the coloration of the solution from yellow to blue or crimson, respectively. Test strips containing diarylethenes were prepared for the easy detection of these ions.

A series of rhodamine 6G derivatives with o-hydroxyarylimine substituents have been synthesized. The obtained compounds in acetonitrile have been found capable of the H+-induced transformation of the spirolactam form into the open one. The process has been accompanied by the formation of a new long-wave absorption maximums at 527–529 nm and fluorescence bands at 557–560 nm. The compound containing 2-hydroxy-4-dimethylaminophenyl substituent has exhibited switching of emission at 429 nm in the presence of Zn2+ cations. This fluorescence has been quenched selectively by the CN− anions. Copper(II) cations have caused the transformation of the spiro structure of rhodamine bearing 2-hydroxy-3-tert-butylbenzofuran group into the open form. The isomerization has been accompanied by chromogenic naked-eye effect: change in the solution color from pale yellow to pink and the appearance of fluorescence at 556 nm. The observed ion-induced spectral transformations can be used in the design of optical and fluorescent chemosensors.

Diarylethenes containing coumarin and thiophene substituents in the thiazole bridge and quinoline receptor fragments have been synthesized. 2-Chloroquinoline diarylethenes have afforded colored cyclic hexadiene forms under UV irradiation, which have undergone reverse isomerization when exposed to visible light. 2-Hydroxyquinoline diarylethenes have been found nonphotochromic. The ionochromic effects of interaction with fluoride anions as well as copper(II) and nickel(II) cations have been studied.

Синтезированы имины 4-формил-3-гидрокси-2-нафтойной кислоты. Исследованы их спектрально-люминесцентные и ионохромные свойства. В спектрах ариламинов в ацетонитриле наблюдается небольшой гипсохромный сдвиг полосы поглощения при добавлении катионов d-металлов без заметного изменения окраски раствора. Спектры испускания близки к исходным спектрам флуоресценции лигандов, лишь в случае иона меди(II) наблюдается практически полное тушение флуоресценции. Бензилимин демонстрирует селективное относительное увеличение интенсивности эмиссии I/I0 в 180 раз в присутствии катионов цинка. Все синтезированные имины проявляют отчетливый «naked-eye» эффект с изменением ярко-желтого цвета раствора на бледно-желтый в случае фторид- и цианид-анионов, тогда как остальные анионы незначительно влияют на характер абсорбции. В случае бензилимина отмечены рекордные значения относительного увеличения интенсивности эмиссии I/I0 – 470 и 575 для цианид- и фторид-анионов соответственно. Таким образом, бензилимин 4-формил-3-гидрокси-2-нафтойной кислоты представляет собой эффективный и селективный полифункциональный флуоресцентный сенсор для детектирования ионов Zn, F и CN.

The reaction of 2,3-diaminonaphthalene with dimedone gave 3-[(3-amino-2-naphthyl)amino]-5,5-dimethylcyclohex-2-en-1-one that reacts with alloxan to afford a product of addition at the enamine moiety. The latter is converted to a spiro derivative on heating in CF3COOH, or undergoes condensation with 2,6-di-tert-butyl-p-benzoquinone to give a benzophenazinone derivative with a sterically hindered phenol substituent.

A rhodamine B derivative containing a terminal (4-hydroxybenzyl)triphenylphosphonium chloride substituent was synthesized. Its structure was determined using IR, 1H NMR, and 13C NMR spectroscopy. The spectral luminescent properties of the compound obtained and its complex formation in solutions with Co2+, Cu2+, Ni2+, and Zn2+ cations were studied. These ions are responsible for a contrasting ionochromic naked-eye effect with the crimson-red coloration of a colorless solution due to the isomerization of the rhodamine spirolactam form into an open form. The process is accompanied by the appearance of fluorescence in the region of 560–600 nm. The complex with zinc(II) cation exhibits particularly intensive emission, which gives the properties of a highly sensitive and effective chemosensor for Zn2+ ions to the obtained rhodamine.

Novel "naked eye" chromofluorogenic chemosensors for biologically important anions F-, CN-, AcO- and H2PO4- based on 5-chloro-2-hydroxy- (1), 3,5-dichloro-2-hydroxy- (2) and 3-bromo-2-hydroxy-5-methoxybenzylidene (3) azomethine imines were synthesized. Their structure and sensing properties were studied using H-1, COSY, C-13, HSQC, HMBC and N-15 NMR, UV-Vis/fluorescence spectroscopy, X-ray diffraction analysis and DFT calculations. Compounds 1-3 exhibit low-intensity emission at 537-574 nm with an anomalous Stokes shift of 7830-8420 cm(-1). In the presence of F-, CN-, AcO- and H2PO4- ions, this emission is completely quenched and a new intense fluorescence appears at 540-590 nm with values of the relative enhancement in fluorescence intensity (I/I-0) 15-79 ((F)-) and 10-137 (CN-). Simultaneously "naked-eye" chromogenic effect is observed with a color change from pale yellow to intense yellow or orange. These spectral responses were attributed to the OH center dot center dot center dot An(-) bonding up to the deprotonation. The association constants found for fluoride anion are 5.5 x 10(8) M-2 (1), 1.3 x 10(3) M-1 (2) and 5.3 x10(8) M-2 (3), and to cyanide anion - 2.8 x 10(3) M-1 (1), 2.0 x 10(3) M-1 (2) and 2.8 x 10(3) M-1 (3). UV-Vis limits of detection for the F- ion are 2.0-6.0 mu M (1), and for the CN- ion - 1.0-2.0 mu M. (c) 2022 Elsevier B.V. All rights reserved.

A series of rhodamine B derivatives containing hydroxyimine receptor fragments was synthesized. The reaction of a 1-hydroxynaphthalene-2-carbaldehyde derivative in acetonitrile proceeds selectively with copper(II) cations and is accompanied by chromogenic naked-eye effect, a change in color from pale yellow to crimson red (λabs 548 nm) due to the cation-induced opening of the spirolactam ring, and the appearance of fluorescence in the region of 578 nm. The subsequent addition of CN– ions to the in situ formed complex leads to its selective anion-induced reverse isomerization into the spiro form, and the original spectral parameters are restored. In ethanol, o-hydroxy(dihydroxy)naphthalenecarbaldehyde derivatives selectively detect Al3+ cations that induce the rhodamine spirolactam ring opening with the attendant chromogenic naked eye effect, a change in the color of the solution from pale yellow to crimson violet, and a burst of strong fluorescence (λfl 584 nm).

Осуществлен синтез серии тиосемикарбазонов замещенных хинолин-3-карбальдегидов. 2-фенилэтинилхинолиновый тиосемикарбазон селективно ионохромен по отношению к ионам Cu и Hg в ацетонитриле. При этом бесцветный раствор окрашивается в желтый цвет, а исходная эмиссия лиганда смещается в длинноволновую область и становится более интенсивной. Тетразол[1,5-a]хинолиновое производное демонстрирует контрастный ионохромный naked-eye эффект в присутствии катионов Cd, Hg и Cu окраска раствора в случае ионов меди меняется на ярко-желтую. 2-оксо-1,2-дигидрохинолиновое производное также проявляет ионохромные свойства по отношению к указанным катионам, однако новые максимумы поглощения находятся в более коротковолновой области спектра. В присутствии ионов кадмия(II) наблюдается селективное увеличение интенсивности эмиссии (I/I) в 90 раз, что превосходит параметры чувствительности большинства известных флуоресцентных сенсоров на Cd2+. Обнаруженные закономерности свидетельствуют о большом потенциале замещенных тиосемикарбазонов в области сенсорики и могут быть использованы при создании ионохромных и флуоресцентных хемосенсоров для экспресс-анализа катионов.

An effective approach to the synthesis of diarylethene-amino acid hybrids DE-Gly, DE-AABA and DE-DAA (5a-d - 7-a-d) was developed via condensation of furan-2,5-dione-based diarylethenes (DE) and ethyl esters of glycine (Gly), alpha-aminobutyric acid (AABA) and D-aspartic acid (DAA) with moderate to good yields. According to X-ray diffraction data, DE-Gly hybrid 5a exists in an antiparallel conformation with a distance of 4.549 angstrom between the reactive carbon atoms C(1)-C(11), potentially capable of forming a single bond, which is suitable for the conrotatory photocyclization reaction allowed by the Woodward-Hoffman rules. The structures of the obtained compounds were proved by H-1, COZY, HSQC, HMBC and C-13 NMR spectroscopy. The hybrids DE-Gly, DE-AABA and DE-DAA absorb at 443-456 nm, which corresponds to their existence in a ring-open form O, and display fluorescence at 531-612 nm. Irradiation with light of 436 nm results in their rearrangement into ring-closed colored nonfluorescent isomers C. Backwards re-opening occurs under the action of visible light (lambda > 500 nm). Spectral kinetic investigation of 5a,c revealed that the efficiency of photocyclization, as well as the emission quantum yield, decreases with the growth of solvent polarity. The ring-closed isomer C of sterically hindered 5a (R-2 = R-3 = Me) is stable at room temperature, whereas for 5c (R-3 = H), ring opening readily occurs with the speed increasing with the polarity of the solvent. The internal emission of sterically hindered hybrids 5a, 6a and 7a (R-2 = R-3 = Me) is reversibly modulated in a binary response with good fatigue resistance under successive irradiation with light of 436 and 540 nm. (C) 2021 Elsevier B.V. All rights reserved.

Here, we report a new photosensitive metal–organic framework (MOF) that was constructed via the modification of UiO-66-NH2 with diarylethene molecules (DAE, 4-(5-Methoxy-1,2-dimethyl-1H-indol-3-yl)-3-(2,5-dimethylthiophen-3-yl)-4-furan-2,5-dione). The material that was obtained was a highly crystalline porous compound. The photoresponse of the modified MOF was observed via UV–Vis and IR spectroscopy. Most of the DAE molecules inside of the UiO-66-pores had an open conformation after synthesis. However, the equilibrium was able to be shifted further toward an open conformation using visible light irradiation with a wavelength of 520 nm. Conversely, UV-light with a wavelength of 450 nm initiated the transformation of the photoresponsive moieties inside of the pores to a closed modification. We have shown that this transformation could be used to stimulate hydrogen adsorption–desorption processes. Specifically, visible light irradiation increased the H2 capacity of modified MOF, while UV-light decreased it. A similar hybrid material with DAE moieties in the UiO-66 scaffold was applied for hydrogen storage for the first time. Additionally, the obtained results are promising for smart H2 storage that is able to be managed via light stimuli.

Synthesis and structure of two novel dyads including two fluorophores - 1,2,4,5-tetraarylimidazole and azomethine fragments of different nature, have been studied targeting compounds with tunable luminescence. The presence of multiple fluorescence in both dyads has been established, and switching in one of the compounds is controlled by the excitation wavelength.