Showing papers on "Xanthene published in 2023"

Catalyst-Free Photochemical Activation of Peroxymonosulfate in Xanthene-Rich Systems for Fenton-Like Synergistic Decontamination: Efficacy of Proton Transfer Process.

Abstract: Catalyst-free visible light assisted Fenton-like catalysis offers opportunities to achieve the sustainable water decontamination, but the synergistic decontamination mechanisms are still unclear, especially the effect of proton transfer process (PTP). The conversion of peroxymonosulfate (PMS) in photosensitive dye-enriched system was detailed. The photo-electron transfer between excited dye and PMS triggered the efficient activation of PMS and enhanced the production of reactive species. Photochemistry behavior analysis and DFT calculations revealed that PTP was the crucial factor to determine the decontamination performance, leading to the transformation of dye molecules. The excitation process inducing activation of whole system was composed of low energy excitations, and the electrons and holes were almost contributed by LUMO and HOMO. This work provided new ideas for the design of catalyst-free sustainable system for efficient decontamination.

Xanthene-Based Nitric Oxide-Responsive Nanosensor for Photoacoustic Imaging in the SWIR Window.

Abstract: Shortwave infrared (SWIR) dyes are characterized by their ability to absorb light from 900 to 1400 nm, which is ideal for deep tissue imaging owing to minimized light scattering and interference from endogenous pigments. An approach to access such molecules is to tune the photophysical properties of known near-infrared dyes. Herein, we report the development of a series of easily accessible (three steps) SWIR xanthene dyes based on a dibenzazepine donor conjugated to thiophene (SCR-1), thienothiophene (SCR-2), or bithiophene (SCR-3). We leverage the fact that SCR-1 undergoes a bathochromic shift when aggregated for in vivo studies by developing a ratiometric nanoparticle for NO (rNP-NO), which we employed to successfully visualize pathological levels of nitric oxide in a drug-induced liver injury model via deep tissue SWIR photoacoustic (PA) imaging. Our work demonstrates how easily this dye series can be utilized as a component in nanosensor designs for imaging studies.

Discovering a Dihydrofluorescein Analogue as a Promising Fluorescence Substrate to HRP

Abstract: Horseradish peroxidase (HRP) combined with its fluorescence substrates is attracting increasing attention for biochemical analysis. Amplex red is the most widely used fluorescence substrate to HRP; however, it suffers from some drawbacks, such as nonspecific responsiveness toward carboxylesterases. Discovering a new small molecular fluorescence substrate with improved sensitivity and selectivity for HRP is thus desired. Herein, three dihydrofluorescein derivatives (DCFHs) are presented to serve as HRP substrates through fluorescence turn-on methods. The most promising one, 2,7-dichloro-9-(2-(hydroxymethyl)phenyl)-9H-xanthene-3,6-diol (DCFH-1), exhibited excellent sensitivity in the detection of HRP. Moreover, DCFH-1 does not respond to carboxylesterase, thus holding advantages over Amplex red. In the further study, the detection reagent in the commercial ELISA kits was replaced with DCFH-1 to establish a new fluorescence ELISA, which works very well in the quantification of inflammatory cytokine biomarkers from in vitro models.

THQ–Xanthene: An Emerging Strategy to Create Next‐Generation NIR‐I/II Fluorophores

Abstract: Near‐infrared fluorescence imaging is vital for exploring the biological world. The short emissions (<650 nm) and small Stokes shifts (<30 nm) of current xanthene dyes obstruct their biological applications since a long time. Recently, a potent and universal THQ structural modification technique that shifts emission to the NIR‐I/II range and enables a substantial Stokes shift (>100 nm) for THQ‐modified xanthene dyes is established. Thus, a timely discussion of THQ–xanthene and its applications is extensive. Hence, the advent, working principles, development trajectory, and biological applications of THQ–xanthene dyes, especially in the fields of fluorescence probe‐based sensing and imaging, cancer theranostics, and super‐resolution imaging, are introduced. It is envisioned that the THQ modification tactic is a simple yet exceptional approach to upgrade the performance of conventional xanthene dyes. THQ–xanthene will advance the strides of xanthene‐based potentials in early fluorescent diagnosis of diseases, cancer theranostics, and imaging‐guided surgery.

Xanthene-based functional dyes: towards new molecules operating in the near-infrared region.

Abstract: Xanthene-based functional dyes have diverse applications in life science and materials science. A current challenge is to develop new dyes with suitable physicochemical properties, including near-infrared (NIR) operation, for advanced biological applications such as medical diagnostics and molecular imaging. In this review, we first present an overview of xanthene-based functional dyes and then focus on synthetic strategies for modulating the absorption and fluorescence of dyes that operate in the NIR wavelength region with bright emission and good photostability. We also introduce our work on aminobenzopyranoxanthenes (ABPXs) and bridged tetra-aryl-p-quinodimethanes (BTAQs) as new xanthene-based far-red (FR)/NIR absorbing/emitting molecules whose absorption/fluorescence wavelengths change in response to external stimuli.

Methyl 5′-Chloro-8-formyl-5-hydroxy-1′,3′,3′-trimethyl-spiro-[chromene-2,2′-indoline]-6-carboxylate

Abstract: 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.

A xanthene-based probe with dual reaction sites enables fluorescence turn-on detection of thiophenol in an aqueous medium

Abstract: A xanthene fluorophore-based probe, Xanth-NO2, has been reported for the detection of thiophenol. Xanth-NO2 exhibited quenched fluorescence in the aqueous buffer due to its aggregate state, which allows the fluorescence...

Assessment of Dye-Absorbed Eggshell Membrane Composites as Solid Polymer Electrolyte of Fuel Cells

Abstract: Recently, polymer electrolytes have been developed for high-performance and eco-friendly fuel cells. Among the candidates, eggshell membrane (ESM) has been promising because of its abundance to assemble various energy devices with low cost and its absorption ability of organic materials. In this work, we investigated fuel cells that included ESM-absorbing xanthene-, triphenylmethane-, and azo-type tar dye, which contained abundant hydrophilic groups, as polymer electrolytes. We found out two points: (1) that the fuel cells that included ESM-absorbing xanthene-type dye generated the highest I–V performance, and (2) the basic molecular structures of the tar dyes determined the correlation of the maximum power and proton conductivities.

Development of ZnO/PANI/Ag nanocomposite for synthesis of bioactive xanthene‐1,8(2 H )‐dione derivatives

Abstract: In this work, we have developed an effective and novel heterogeneous ZnO/polyaniline (PANI)/Ag nanocomposite, which was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDAX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM). ZnO nanoparticles were prepared by coprecipitation method at low temperature. The obtained ZnO nanoparticles were used for its surface functionalization with PANI-supported silver nanoparticles via self-assembly redox polymerization method. Further, the high catalytic activity of ZnO/PANI/Ag nanocatalyst was investigated for the one-pot synthesis of xanthene derivatives via condensation of 5,5-dimethylcyclohexane-1,3-dione and different aromatic aldehydes under neat reaction condition. The advantage of this current work includes short reaction time, easy work-up, solvent free, high product yield, good chemistry metrices values, easily recoverable and reusable catalyst up to six cycles.

Deep Red to NIR Emitting Xanthene Hybrids: Xanthene‐Hemicyanine Hybrids and Xanthene‐Coumarin Hybrids

Abstract: Xanthene dyes exhibit remarkable photophysical properties and photostability. Their ability to switch fluorescence on/off depending on the external environment makes them a promising candidate for imaging/sensing/tracking/labeling probes. However, their emission ≤600 nm and Stokes shift ∼34 nm restrict their use in biological applications. A well-known approach to shifting the emission of xanthene dyes in the deep red to Near infrared (NIR) is by forming xanthene hybrids. This review gives a comprehensive list of the deep red to NIR xanthene-hemicyanine and xanthene-coumarin hybrids. We have outlined general synthetic strategies and a detailed discussion of substituent effect, π-conjugation, and ring effect on the photophysical properties of these dyes. A section on applications of deep red to NIR xanthene hybrids based on fluorophore-linker strategy and spirocyclization is included. This review highlights the structure-spectroscopic relationships, which will be useful in designing new deep red to NIR xanthene analogs.

Ways of light stabilization of natural dyes using fullerene C60

Abstract: Среди технических функциональных продуктов в различных отраслях промышленности особое место занимают красители, количество которых в настоящее время составляет более 10 тыс. индивидуальных веществ различных классов (азокрасители, антрахиноновые, ксантеновые, тиазиновые, акридиновые и др.). Для практических целей в пищевой промышленности востребованы яркие, светостойкие и безвредные красители природного и синтетического происхождения. Имеющееся количество видов таких красителей недостаточно для удовлетворения всех потребностей различных производств. Особенно востребованы красители с повышенной светостойкостью. Поэтому в настоящее время получение новых видов светостойких красителей и разработка технологий их производства являются весьма актуальными. Представлены результаты экспериментов по подбору исходного растительного сырья для выделения природных антоциановых красителей методом водной экстракции из ягодного жмыха водой, которая предварительно настаивалась на шунгитовом щебне, содержащем фуллерен. Установлено интенсифицирующее действие шунгитовой воды на степень извлечения антоцианов методом экстракции. Предложен механизм экстракционного выделения красителей. Для светостабилизации красителей, выделенных при экстракции, проведена их адсорбция на порошковых материалах, состоящих из углеводов и белков. Полученные цветные порошки обладали высокой светостойкостью. Предложены механизм светостабилизации красителей и пути использования светостабилизированных красителей. На основании проведенного аналитического обзора определено наиболее рациональное направление выделения антоциановых красителей из доступного природного сырья в присутствии инновационного наноматериала - фуллерена, обладающего антиоксидантными и антирадикальными свойствами. С целью повышения эффективности водной экстракции проведены исследования по изучению способов предварительной подготовки исходного сырья, необходимых для увеличения степени выделения красных натуральных красителей. Разработан новый способ выделения и длительного сохранения цветности антоциановых красителей методом нанесения их на твердые формы углеводов и белков различного химического строения в присутствии фуллерена. Предложен антирадикальный механизм повышения светостойкости антоциановых и беталаиновых красителей. Among the technical functional products in various industries, a special place is occupied by dyes, the number of which currently amounts to more than 10 thousand individual substances of various classes (azo dyes, anthraquinone, xanthene, thiazine, acridine, etc.). For practical purposes in the food industry, bright, light-resistant and harmless dyes of natural and synthetic origin are in demand. The available number of types of such dyes is not enough to meet all the needs of various industries. Dyes with increased light resistance are especially in demand. Therefore, at present, the production of new types of light-resistant dyes and the development of technologies for their production are very relevant. The results of experiments on the selection of initial plant raw materials for the isolation of natural anthocyanin dyes by water extraction from berry cake with water that was previously infused on shungite crushed stone containing fullerene are presented. The intensifying effect of shungite water on the degree of anthocyanin extraction by extraction has been established. The mechanism of extraction of dyes is proposed. For light stabilization and dyes isolated during extraction, their adsorption was carried out on powdered materials consisting of carbohydrates and proteins. The resulting colored powders had high light resistance. The mechanism of light stabilization of dyes and ways of using light-stabilized dyes are proposed. Based on the conducted analytical review, the most rational direction of isolation of anthocyanin dyes from available natural raw materials in the presence of an innovative nanomaterial - fullerene, which has antioxidant and antiradical properties, has been determined. In order to increase the efficiency of water extraction, studies have been conducted to study the methods of preliminary preparation of raw materials necessary to increase the degree of isolation of red natural dyes. A new method has been developed for the isolation and long-term preservation of anthocyanin dyes by applying them to solid forms of carbohydrates and proteins of various chemical structures in the presence of fullerene. An antiradical mechanism for increasing the light resistance of anthocyanin and betalain dyes is proposed.

Catalyst‐Free Photochemical Activation of Peroxymonosulfate in Xanthene‐Rich Systems for Fenton‐Like Synergistic Decontamination: Efficacy of Proton Transfer Process

Abstract: Catalyst-free visible light assisted Fenton-like catalysis offers opportunities to achieve the sustainable water decontamination, but the synergistic decontamination mechanisms are still unclear, especially the effect of proton transfer process (PTP). The conversion of peroxymonosulfate (PMS) in photosensitive dye-enriched system was detailed. The photo-electron transfer between excited dye and PMS triggered the efficient activation of PMS and enhanced the production of reactive species. Photochemistry behavior analysis and DFT calculations revealed that PTP was the crucial factor to determine the decontamination performance, leading to the transformation of dye molecules. The excitation process inducing activation of whole system was composed of low energy excitations, and the electrons and holes were almost contributed by LUMO and HOMO. This work provided new ideas for the design of catalyst-free sustainable system for efficient decontamination.

Scope and Mechanistic Studies on the Ruthenium-Catalyzed Multicomponent Deaminative C–H Coupling Reaction of Phenols with Aldehydes and Enamines for the Formation of Xanthene and Dioxacyclic Derivatives

Abstract: The in situ generated catalytic system from the tetranuclear Ru–H complex [(PCy3)(CO)RuH]4(O)(OH)2 (1) with 3,4,5,6-tetrachloro-1,2-benzoquinone (L1) has been found to mediate a multicomponent deaminative coupling reaction of phenols with aldehydes and enamines to form xanthene products. The multicomponent C–H coupling reaction of phenols with 2-hydroxybenzaldehydes and cyclic enamines efficiently installed the tricyclic 1,3-dioxacin derivatives, while the analogous coupling reaction of phenols with 2-hydroxybenzaldehydes and triethylamine selectively formed bicyclic 1,5-dioxacyclic derivatives. The density functional theory (DFT) calculations established two energetically viable mechanistic pathways for the formation of xanthene products, in which both pathways identified the C–O bond cleavage step as the turnover limiting step. A Hammett plot from the coupling reaction of 3,5-dimethoxyphenol with an enamine and para-substituted benzaldehydes p-X-C6H4CHO (X = OMe, Me, H, Cl, CF3) showed a negative slope (ρ = −0.98). The calculated energy analysis showed a similar trend (ρ = −0.59) for the mechanism via the C–O cleavage rate-limiting step. The combined experimental and DFT computational results support a mechanistic path that involves the dehydrative C–H coupling of phenol with aldehyde, followed by the deaminative coupling reaction with an enamine in forming the xanthene product.

Ultrasound-assisted synthesis of 9-(4-Hydroxyphenyl)-3,4,5,6,7,9-Hexahydro-1H-Xanthene-1,8(2H)-Dione using lime juice catalyst and its antibacterial activity

Abstract: In the previous study, the 9-(4-hydroxyphenyl)-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione has been successfully synthesized using lime juice as a green catalyst. Condition optimization was still needed to enhance the reaction yield. In this research, the compound has been synthesized using lime juice assisted by ultrasonic irradiation. The use of ultrasonic waves aimed to enhance product yield and reduce reaction time and temperature when lime juice was applied as the catalyst at the reaction. The non-catalyst compound was synthesized using water as a solvent and assisted by ultrasonic irradiation, producing a yield of 45.16%. In contrast, the lime juice catalyst synthesized product brings a higher yield of 89.03%. This study discusses the role of lime juice catalysts in improving yield percentage and decreasing reaction time and temperature. The synthesized compound 1 was in the form of white powder with a melting point of 228-230°C. GC-MS analysis of compound 1 confirms a single peak with a retention time of 15.497 minutes and a peak with an m/z value of 310.1 in.the MS spectrum as molecular ion of the compound. The presence of a phenolic group at the compound induces its antibacterial activity. However, the antibacterial test showed that the compound has weak antibacterial activity against Escherichia coli and no activity against Staphylococcus aureus.

Efforts toward PET-Activatable Red-Shifted Silicon Rhodamines and Silicon Pyronine Dyes

Abstract: Tracers for bimodal optical imaging and positron emission tomography unite multiple advantages in a single molecule. Their tumor-specific uptake can be visualized after their PET activation by radiofluorination via PET/CT or PET/MRI allowing for staging or therapy planning, while their non-radioactive moiety additionally facilitates the visualization of malignant tissue during intraoperative fluorescence-guided surgery or in histological assessments. The silicon-bridged xanthene core offers the opportunity for radiofluorination with SiFA isotope exchange to obtain a small-molecule, PET-activatable NIR dye that can be linked to different target vectors. Herein, we demonstrate for the first time the PET-activation of a fluorinated silicon pyronine, belonging to a class of low-molecular-weight fluorescence dyes with a large Stokes shift (up to 129 nm) and solvent-dependent NIR dye properties, with a successful radiochemical conversion of 70%. The non-fluorinated pyronine precursor is easily accessible by a three-step sequence from commercially starting material with a 12% overall yield. Moreover, a library of seven unusually functionalized (by approximately 15 nm), red-shifted silicon rhodamines were synthesized in three- to four-step sequences and the optical properties of the novel dyes were characterized. It was also shown that the synthesized silicon rhodamine dyes can be easily conjugated by amide bond formation or ‘click-reaction’ approaches.

Acridine yellow G as a photo-induced electron transfer catalyzed radical metal-free synthesis of tetrahydrobenzo[b]pyran scaffolds in an aqueous media

Abstract: We established a green approach for the radical synthesis of tetrahydrobenzo[b]pyran scaffolds by using Knoevenagel-Michael tandem cyclocondensation of aldehyde derivatives, malononitrile, and dimedone. Using visible light as a renewable energy source, a photo-induced electron transfer (PET) photocatalyst was exploited in an aqueous solution. A low-cost, readily available non-metal dye is the goal of this research. The photochemically catalyzed acridine yellow G (AYG) exhibits high yields, energy efficiency, and environmental friendliness, as well as speed-saving characteristics and ease of use. This allows for tracking of environmental and chemical variables over time. In this study, turnover number (TON) and turnover frequency (TOF) of tetrahydrobenzo[b]pyran scaffolds were determined. It is remarkable that gram-scale cyclization is feasible, indicating that it can be applied to industry.

Bio‐Based Hybrid Catalysts for the Synthesis of Pharmacologically Active Xanthenes

Abstract: We synthesized an efficient bio-based nano-catalyst, – Fe3O4@nano linear dextrin/Sb+5 (Fe3O4@NLD/Sb+5) – from nano linear dextrin and antimony pentachloride via straightforward steps. The nano-catalyst was used to synthesize solvent-free 14-aryl-14H- dibenzo[a, j]xanthene derivatives based on 2-aminobenzimide and different aldehydes. The synthesized nano-catalyst bears many critical advantages: nontoxicity, biocompatibility, affordability, easy work-up method, environmentally friendliness, and high yields, as well as being solvent-free and operable under green conditions.

Investigating the Effects of Donors and Alkyne Spacer on the Properties of Donor-Acceptor-Donor Xanthene-Based Dyes

Abstract: NIR dyes have become popular for many applications, including biosensing and imaging. For this reason, the molecular switch mechanism of the xanthene dyes makes them useful for in vivo detection and imaging of bioanalytes. Our group has been designing NIR xanthene-based dyes by the donor-acceptor-donor approach; however, the equilibrium between their opened and closed forms varies depending on the donors and spacer. We synthesized donor-acceptor-donor NIR xanthene-based dyes with an alkyne spacer via the Sonogashira coupling reaction to investigate the effects of the alkyne spacer and the donors on the maximum absorption wavelength and the molecular switching (ring opening) process of the dyes. We evaluated the strength and nature of the donors and the presence and absence of the alkyne spacer on the properties of the dyes. It was shown that the alkyne spacer extended the conjugation of the dyes, leading to absorption wavelengths of longer values compared with the dyes without the alkyne group. In addition, strong charge transfer donors shifted the absorption wavelength towards the NIR region, while donors with strong π-donation resulted in xanthene dyes with a smaller equilibrium constant. DFT/TDDFT calculations corroborated the experimental data in most of the cases. Dye 2 containing the N,N-dimethylaniline group gave contrary results and is being further investigated.

Xanthene‐Based Nitric Oxide‐Responsive Nanosensor for Photoacoustic Imaging in the SWIR Window

Abstract: Shortwave infrared (SWIR) dyes are characterized by their ability to absorb light from 900 to 1400 nm, which is ideal for deep tissue imaging owing to minimized light scattering and interference from endogenous pigments. An approach to access such molecules is to tune the photophysical properties of known near-infrared dyes. Herein, we report the development of a series of easily accessible (three steps) SWIR xanthene dyes based on a dibenzazepine donor conjugated to thiophene (SCR-1), thienothiophene (SCR-2), or bithiophene (SCR-3). We leverage the fact that SCR-1 undergoes a bathochromic shift when aggregated for in vivo studies by developing a ratiometric nanoparticle for NO (rNP-NO), which we employed to successfully visualize pathological levels of nitric oxide in a drug-induced liver injury model via deep tissue SWIR photoacoustic (PA) imaging. Our work demonstrates how easily this dye series can be utilized as a component in nanosensor designs for imaging studies.

Efficient Fe 3 O 4 @TiO 2 Composite Nanoparticles Catalyzed Synthesis of Novel Azo Xanthene Dyes with Promising Antimicrobial Activity

Abstract: A number of novel azo xanthene dyes were prepared via a convenient and rapid cyclocondensation reaction of 3,4-methylenedioxyphenol with pre-synthesized (E)-1,2-diphenyl-1-diazenes in the molar ratio of 2 : 1. The synthesis was carried out in the presence of Fe3O4@TiO2 composite nanoparticles in aqueous ethanol solution at room temperature. This method offers several benefits such as simple experimental work-up procedure, maximum eco-friendly manner, short reaction time, and especially high yields of products. The synthesized dyes were investigated for their antibacterial activity and very good results were obtained.

Chromene-Dihydropyrimidinone and Xanthene-Dihydropyrimidinone hybrids: design, synthesis, and antibacterial and antibiofilm activities.

Abstract: Abstract A series of eleven Chromene-Dihydropyrimidinone and eleven Xanthene-Dihydropyrimidinone hybrid compounds were easily synthesized through a sequential multicomponent reaction followed by the Copper-catalyzed Alkyne-Azide Cycloaddition reaction. The antibiofilm and antibacterial...

Total Biosynthesis of Mutaxanthene Unveils a Flavoprotein Monooxygenase Catalyzing Xanthene Ring Formation.

Abstract: Flavoprotein monooxygenases (FPMOs) play important roles in generating structural complexity and diversity in natural products biosynthesized by type II polyketide synthases (PKSs). In this work, we use genome mining to discover novel mutaxanthene analogs and investigate the biosynthesis of these aromatic polyketides and their unusual xanthene framework. We disclosed the complete biosynthetic pathway of mutaxathene through in vivo gene deletion and in vitro biochemical experiments. We showed a multifunctional FPMO, MtxO4, catalyzes ring rearrangement and generates the required xanthene ring through multi-step transformation. In addition, we have successfully obtained all necessary enzymes for in vitro reconstitution, and total biosynthesize mutaxanthene in a step-wise manner. Our results revealed the formation of a rare xanthene ring in type II polyketide biosynthesis, and demonstrates the potential of using total biosynthesis for the discovery of natural products synthesized by type II PKSs.