Properties Of Dyes Research Articles

Ultrafast Excitonic Transitions in Enantiopure and Racemic Squaraine Thin Films

ABSTRACTWhile chirality is a prevalent character of numerous biological and synthetic organic molecules, its selective absorption of circularly polarized light, known as circular dichroism (CD), is typically small due to intrinsically weak coupling between magnetic and electric dipoles. However, thin films of aggregated, enantiopure prolinol‐derived squaraine molecules (ProSQ‐C16) exhibit an unusually large excitonic CD signal, although the underlying mechanism is not yet known. In this study, we employ steady‐state and ultrafast transient absorption spectroscopy to investigate the nature and dynamics of excitons in aggregates of enantiopure and racemic ProSQ‐C16 thin films. Highly resembling transient responses of enantiopure thin films under excitations at different photon energies strongly indicate that a single type of aggregate dominates the linear optical response, that is, a strong red‐shifted (J‐like) and weak blue‐shifted (H‐like) absorption band. On the other hand, the transient properties of the racemic thin film deviate from this pattern and remain largely ambiguous. The short lifetime of excited states and coherent oscillations present in the dynamics of the transient absorption signal indicate that the early time dynamics are governed by a transition towards a dark intermediate state, which might arise from intermolecular charge transfer with potential contributions from the coupling of excitons to the vibrations. This non‐radiative relaxation pathway explains the unusually weak fluorescence of the predominately J‐like behaving aggregate. Our findings conclusively show that the chiral aggregate structure has a strong impact on the optical and dynamic response of the excitons and underline the significance of non‐Frenkel exciton states for the optical properties of anilino squaraine dyes.

Kinetic Modeling of Brilliant Blue Discoloration by Ozonation

This paper presents the results of investigations on the kinetic modeling of Brilliant Blue FCF (BB) discoloration reactions in aqueous solutions with different ozone concentrations and pH conditions. Kinetic studies involve knowledge of the structure and properties of dye and ozone, as well as of the experimental conditions. In general, scientists admit that the predominant oxidation pathway is direct (by free oxygen atoms) or indirect (by free hydroxyl radicals); this will depend on influencing factors such as the physicochemical properties of the dye, the pH of the aqueous solution, ozone concentration, reaction time, and the contact mode with/without stirring. In this experimental research, two pathways were chosen following CBB = f(t)—1. a constant dye concentration and different ozone concentrations, in the concentration range of 100–250 mg/L, in three pH media (acidic, neutral, and basic), with and without stirring; 2. a constant concentration of ozone and different dyes in the concentration range of 2.5–10 mg/L, under the conditions of point 1. With the obtained experimental data, the curves CBB = f(t) were drawn and processed according to the integral method of classical kinetics, based on first- and second-order equations. Unfortunately, this simple procedure did not give any results for the pH values studied. The rate constants were negative, and/or the reaction order depended on the initial conditions. Due to its structure, the BB dye has several chromophore groups, and thus multiple attack centers, resulting in several oxidation by-products, which is why the 1H-NMR spectrum was recorded for the discoloration of BB with ozone. Since the stoichiometry of the overall oxidation reaction, as well as the relationship between the rate constant and the reaction conditions mentioned above, is not known, a kinetic model based on mass transfer coupled with a chain reaction in the bulk liquid phase was proposed and successfully tested at pH = 7. This research approach also involves the consolidation of the theoretical bases of the ozonation process through the kinetic study carried out, as well as the proposal of a kinetic model. These systematics lead to results that are applicable to other aqueous systems that are impure with dyes, allowing for generalizations and the development of the field, ensuring the sustainability of the research.

Green synthesis of silver nanoparticles on polyamide fabrics using Scrophularia striata Boiss extract: Characterization, dyeing, and antibacterial properties

The green synthesis of silver nanoparticles (Ag NPs) on textiles using natural extracts is emerging as an innovative, eco-friendly approach for enhancing both antibacterial properties and dyeing performance. This study introduces a novel in-situ method for synthesizing Ag NPs directly on polyamide (PA) fabrics, utilizing Scrophularia striata Boiss extract (SBE) as a natural dye and reducing agent. UV–visible spectroscopy and dynamic light scattering (DLS) were used to characterize the synthesis process and determine the average particle size of Ag NPs. The data showed particle sizes of 62.5 nm and 56.1 nm when using flower and stem extracts, respectively. Surface morphology findings from scanning electron microscopy (SEM) and corresponding diffraction peaks in X-ray diffraction (XRD) confirmed the in situ formation of Ag NPs on the surface of PA fabric. Fabrics dyed with SBE and Ag NPs exhibited higher color strength (K/S values of 4.1 and 5.6 for flower and stem, respectively), showing 64 % and 100 % increases compared to samples without silver. Additionally, PA fabrics exhibited 100 % inhibition against E. coli and S. aureus bacteria. After 10 washing cycles, antibacterial activity was maintained at 88 % and 85 % for the stem extract and 83 % and 79 % for the flower extract. This research highlights the novel integration of natural dye and nanoparticle synthesis, providing a sustainable route for multifunctional textile development.

The Extraction of Alcea Rosea Organic Dye and Its Characterization of Optical Properties

In the present study, the optical properties of a natural dye extracted from Alcea rosea flowers were investigated. The color extraction procedure was performed using a nontoxic solvent ethanol to enhance human safety and the ecological framework. Fourier transform infrared spectroscopy was employed to determine the functional groups of the natural dye obtained from Alcea rosea flowers. The optical properties of dye were achieved by the directed thin film using UV-Vis spectroscopy and analyzed absorption spectra, coefficients, refractive indices, extinction coefficients, and optical energy bandgap. A broad absorption band occurs over an extensive waveband with peak at 380 nm. The occurrence of a low indirect bandgap in a thin film was discerned at 3.9 eV, with Urbach energy noticed in a state of 0.23 eV.

Study of Natural Herbal Dyes Photodegradation Effect to Optical Properties for Dye-Sensitized Solar Cells

The stability of natural dyes for use in dye-sensitive solar cells is known from their photodegradation characteristics. Photodegradation effects using artificial light radiation on natural herbal dyes were investigated. Three natural herbal dyes, namely Fagraea acuminatissima, sappanwood, and kulit setong were used in this study. The stability of the natural herbal dyes under artificial light radiation was studied. The optical properties of the natural herbal dyes as indicators of their stability were characterized using FTIR and UV-VIS absorption. Stability testing of natural herbal dyes was conducted in a room with artificial lighting for 5 weeks. Observations of changes in their optical properties were performed weekly. It can be seen that all three natural herbal dyes contained anthocyanin. In addition to anthocyanin, Fagraea acuminatissima and sappanwood also contain chlorophyll. In contrast, the kulit setong contains beta-carotene in addition to anthocyanin. The degradation percentage showed that sappanwood degrade to all of its pigments. While an increase occurred in the chlorophyll peak of Fagraea acuminatissima and the beta-carotene peak of kulit setong. This clearly shows that Fagraea acuminatissima has the highest stability, and potentially increases the efficiency of solar cells.

Electric field modulation of electronic structure, charge transfer, and nonlinear optical properties of crocetin for dye-sensitized solar cells

Natural sensitizing dyes in solar energy applications have gained attention due to their sustainability, cost-effectiveness, and environmental friendliness. However, enhancing their performance, light-harvesting efficiency, and durability requires a deeper understanding of their structural and electronic properties under solar irradiance. Accordingly, this study explores the electronic structure and nonlinear optical properties of crocetin dye (cis and trans conformers) under varying external electric fields using M06-2X/6-311+G(d,p) model chemistry. The absorption characteristics strongly depend on field intensity, with electron injection efficiency expected to decrease as the field increases. Key nonlinear optical (NLO) parameters, such as dipole moment, polarizability, and hyperpolarizabilities, were calculated at solar irradiance peak frequencies. The NLO properties are wavelength-independent in the infrared region but show significant wavelength dependency in the visible region, increasing substantially near the absorption energy.

Sustainable enhancement of wool fibers using Hymenocrater platystegius flower and natural dyes for improved Insect-Repellent and color properties

This study investigates the application of Hymenocrater platystegius flower as a natural mothproofing agent for wool fibers and examines the effects of aluminum mordanting on the dyeing properties of wool treated with various natural dyes. Wool fibers were treated with Hymenocrater platystegius flower powder and aluminum salts, followed by dyeing with Madder, Reseda lutea, Indigo, or Walnut shell dyes using different mordanting methods. FTIR analysis revealed the characteristic absorption bands and confirmed the interactions between the wool fibers and the treatment agents. The insect-repellent properties were assessed by weight loss measurements after exposure to Anthrenus verbasci larvae, showing significant improvements in treated samples, particularly with the combination of Hymenocrater platystegius and aluminum mordanting. GC–MS analysis of the essential oil identified as α-Pinene, Trans-Verbenol, Linalool, and β-Bourbonene as the main constituents, contributing to the insect-repellent effect. The L*a*b* color space analysis demonstrated that aluminum mordanting significantly enhances the color strength and stability of dyed wool, with pre-mordanting generally providing better results. The study further evaluated the washing and light fastness, as well as the mothproofing properties of the dyed wool samples. These results indicate that the weight loss percentages of treated wool fiber after washing are slightly higher than before washing, but the difference is not significant. Overall, the use of aluminum mordant in conjunction with Hymenocrater platystegius flower powder not only improves the color characteristics of wool dyed with natural dyes but also provides effective mothproofing properties, making it a viable and eco-friendly option for textile applications.

A Multimode Dynamic Color-Changing Device for Smart Windows Based on Integrating Thermochromic and Electrochromic Properties.

Electro- and thermochromic materials have been greatly applied in smart windows and displays due to the excellent properties of color variation and solar radiation. However, the mono color and single response to voltage and temperature hinder their application and development. Here, a multimode dynamic color-changing device (T/ECD) was developed by integrating the electrochromic property of synthetic viologen dyes and the thermochromic properties of hydroxypropyl acrylate (HPA). The T/ECD achieves four modes of optical regulation, namely, colorless transparent state, tinted transparent state, colorless opaque state, and tinted opaque state, which can be regulated independently/coordinately using heat and voltage. The optimized T/ECD switched color at 1.2 V with 15 s or adjusted the transparent/opaque state at >34 °C with 46 s. In addition, based on the red viologen (ViO-R), green viologen (ViO-G), and blue viologen (ViO-B) dyes, colorful T/ECDs were successfully designed and fabricated, and T/ECDs have excellent cycling properties, expanding the application requirement. Moreover, we demonstrated their application in smart windows and privacy protection. The design philosophy and successful exploration have great prospects for energy-saving buildings, displays, and information masking/storage systems.

Review of Angular-Selective Windows with Guest–Host Liquid Crystals for Static Window Applications

This review focuses on the development and advancements in angular-selective smart windows, with particular emphasis on static windows utilizing guest–host liquid crystal (GHLC) systems. Angular-selective windows are designed to adjust their transmittance based on the angle of incident light, offering enhanced energy efficiency and visual comfort in both architectural and automotive applications. By leveraging the anisotropic absorption properties of dichroic dyes, GHLC-based windows can selectively block oblique sunlight while preserving clear visibility from normal viewing angles. Various liquid crystal (LC) alignment configurations, including vertically aligned, homogeneously aligned, hybrid aligned, uniformly lying helix, and twisted aligned LC cells, have been investigated to optimize light control for different installation angles, such as for automotive windshields and building windows. These advancements have demonstrated significant improvements in energy conservation and occupant comfort by reducing cooling demands and regulating sunlight penetration. This review summarizes key findings from recent studies, addresses the limitations of current technologies, and outlines potential future directions for further advancements in smart window technology.

Organic-Inorganic Hybridization of Silkworm Cocoon Filaments Using Nano Pastes of Silica-Phosphate-M (M = Cu, Fe, or Al).

Inorganic-organic hybrid biomaterials have recently attracted much attention because of their widespread use. Silkworm cocoon filaments resulting from sericulture as prospective nanobiomaterials need to be improved, and their properties need to be used for broader purposes. This study was aimed at investigating methods for siliconization of silkworm cocoon filaments and characterizing their cocoon filament properties in terms of their yarn quality, natural dyeing, and antibacterial properties. Three methods of hybridization processes were used in this experiment, namely, in situ natural dyeing of silk yarns while silk filaments were spined, feed engineering through spraying the mulberry leaves with natural dyes and silica-phosphate-M (M = Cu, Fe, or Al) nano pastes, and a combination of both methods. The resulting cocoon filaments were characterized by their siliconization of filament fibers by using FTIR, XRD, and SEM-EDS methods. The yarn tensile strength, color quality, color fastness properties affected by the siliconization of silk filament fibers, and antibacterial properties were also investigated. Results showed that the combination method produced better siliconization of silk fibers, and, consequently, the better siliconization of silk fibers produced better natural dyeing as well as antibacterial properties of their resulting silk yarns.

Study of substituents-regulated dyeing properties in non-aqueous media systems based on MD simulation and DFT

To investigate the relationship between N-acetoxyethyl group and dyeing properties of disperse dyes in D5 non-aqueous medium dyeing system, the adsorption and diffusion behaviors of three disperse dyes with different structures were studied by molecular dynamics (MD). The diffusion coefficients, the planar distribution densities of dyes in different directions, and the intermolecular interaction energies were calculated. Molecular dynamics simulation (MD) was used to calculate molecules polarity index (MPI). Meanwhile, the practical dyeing experiments also were investigated to compare with simulated results. The results showed that the adsorption and diffusion behavior of disperse dyes with different structures were significantly different. Compared with dye B257, D-1 and D-2 are more easily adsorbed and diffused into the interior of the fiber because of the introduction of polar acetoxyethyl group. Moreover, the diffusion coefficient of D-2 in the fiber was relatively low, indicating that the combination between dye and polyester fiber was stable. XY plane distribution density and MPI revealed that the introduction of acetoxyethyl was beneficial to increase the adsorption amount of dye on the fiber, which was mainly related to the high binding energy between dye molecule and polyester fiber. The results of dyeing experiments showed that the decreased solubility of disperse dyes in the D5 medium was conducive to improving the dyeing rate of disperse dyes. This was consistent with the simulated interaction between dyes and D5. This study will provide a basis for further rapid and accurate development and selection of disperse dyes with high dyeing rate in non-aqueous medium systems.

Investigation and optimization of Supercritical CO2 dyeing of cotton with Laccaic acid for sustainable textile production with improved fastness

Supercritical carbon dioxide (scCO2) was employed as a sustainable and ecological means for cotton dyeing using Laccaic acid also known as lac dye. Cotton was pre-treated with polyethylene glycol 600 (PEG) and dyed with benzamide which resulted in a considerable increase in colour strength, fastness properties, and dye adsorption. Colour strength was increased by raising dye intensity from 1% to 3% o.w.f (on weight of fibre) which was evaluated using color strength (K/S) measurements. The optimal K/S of cotton was obtained at 110 °C, 20 MPa and 3h with a dye intensity of 3% o.w.f. Dyeing results implied that pretreated cotton had improved K/S and better fastness with benzamide. The breaking force of dyed cotton was studied. The system parameters affecting the dyeing properties, including the effect of dye auxiliaries, dye concentration, temperature, pressure, and dyeing time were also examined.

Unveiling the Ultrafast Excitation Energy Transfer in Tetraarylpyrrolo[3,2-b]pyrrole-BODIPY Dyads.

We have synthesized two dyads (dyad 1 and 2) comprising of tetraarylpyrrolo[3,2-b]pyrrole (TAPP) and BODIPY. In dyad 1, two BODIPYs are directly connected with TAPP moiety whereas in dyad 2, BODIPYs are connected through phenylethynyl linkers. TAPP is a blue energy donor which is easy to synthesize and functionalize as compared to other well-known blue energy donors like pyrene, perylene etc. This is the first report of using TAPP as an energy donor in BODIPY based dyad molecules. Complete quenching of TAPP fluorescence in the dyads suggests fast energy transfer from TAPP to BODIPY unit (ETE ~ 99.9%). Ultrafast fluorescence and transient absorption spectroscopic studies of dyad 1 showed TAPP to BODIPY energy transfer in 125 fs (kET = 8.0 x 1012 s-1) which is one of the fastest energy transfer events in BODIPY based dyad reported so far. Whereas, in dyad 2, energy transfer is almost four times slower (480 fs, kET = 2.1 x 1012 s-1). These results were rationalized by theoretical Förster formulations. This study shows that suitably matched optical properties of TAPP and BODIPY dyes along with their easy syntheses will be the key to develop highly efficient energy transfer systems in future for multiple applications.

Comparison of infrared-, ultrasonic-, and microwave-assisted mordanting methods for the natural dyeing properties of hemp fabrics

Comparison of infrared-, ultrasonic-, and microwave-assisted mordanting methods for the natural dyeing properties of hemp fabrics

Influence of Green Synthesized Silver and Zinc Nanoparticle on Seed Quality Attributes in Red Sander (Pterocarpus santalinus Linn.)

Red Sanders (Pterocarpus santalinus), or Rakta chandana, is an endangered tree native to the Southern Indian Peninsula, valued for its medicinal and dye properties. However, its germination is hindered by a hard seed coat, phenolic compounds and hormonal imbalances. Nanotechnology in forestry enhances product innovation, paper processes and sustainability through plant-based nanoparticle biosynthesis. The experiment used a completely randomized design (CRD) with three replications and evaluated seven presowing treatments: T1 (AgNPs at 1000 ppm for 24 hours), T2 (ZnNPs at 2000 ppm for 24 hours), T3 (Conc. H2SO4 for 12 minutes), T4 (NaDC 500 ppm), T5 (Dewinging), T6 (soaking in hot water at 100°C for 5 minutes) and T7 (control). The results indicated that seeds treated with ZnNPs at 2000 ppm (T2) exhibited highest germination rate (56%), germination speed (1.04), root length (17.05 cm), shoot length (16.33cm) and highest dry weight (6.22 g) and highest seedling vigour Index-I (1869). In comparison H2SO4 treatment (T3) delivered 51.67 per cent germination and a speed of germination (0.95), with root length (15.28 cm), shoot length (16.22 cm), dry weight (5.24 g) and seedling vigour Index (1628) slightly lower but still significant. The control (T7) had the lowest performance with 31 per cent germination, a speed of 0.36, root length (15.28 cm), shoot length (16.22 cm), lower dry weight (1.63 g) and the lowest Seedling Vigour Index (649). Overall, ZnNPs at 2000 ppm (T2) were the most effective in enhancing germination, seedling growth and overall vigour in Red sanders.

Emerging Thermosensitive Probes Based on Triamino-Phenazinium Dyes.

Temperature is an essential physical characteristic that influences all biological processes. Building on previous research on dialkylamino-functionalized rhodamine-based thermo-sensors, we investigate herein the thermosensitive properties of triamino-phenazinium dyes. Through a simple five-step synthetic route, we synthesized amino-phenazinium chromophores 6 and 7, featuring diethylamine substituents at different positions. A comparative analysis of optical properties and thermosensitivity was conducted on these compounds and an isomer, 5, in which butylamine moiety replaced the diethylamine group. The different emissive behaviors of the three fluorophores emphasize that not only the chemical nature but also the specific position of the alkylamine substituent play fundamental roles in the synthesis of highly emissive thermo-probes.

Revolutionizing dye-sensitized solar cells: Chassalia curviflora fruit extract as photosensitizer and charge recombination inhibitor

The utilization of natural dyes from Chassalia curviflora (CCE), which were successfully extracted to provide bioactive chemicals for the development of dye-sensitized solar cells (DSSCs), is the main focus of this work. These CCEs efficiently absorb light and stop charge recombination in solar cells after being extracted using ethanol. The absorption properties of these natural dyes are discovered to be greatly influenced by the kind and concentration of CCE, with an absorption peak observed at 350 nm. The dyes’ improved adsorption properties on TiO2 are indicated by the presence of functional groups, bond stretching, and bending features, as confirmed by FTIR and UV–Visible spectroscopic investigations. In the DSSC design, these dyes have been effectively combined with an FTO substrate covered with TiO2, serving as a photoanode. The resultant solar cells, which comprise a graphite-based counter electrode, I−/I3− electrolyte, and photoanode, have a power conversion efficiency (PCE) of 0.49 %. The measurements for fill factor, Voc, and Jsc are 0.4761, 1.652 mA/cm2, and 0.52 V, in that order. The phytochemical components of the dye are shown to be crucial in trapping electrons and holes, hence reducing charge recombination and promoting enhanced charge transport towards the titanium dioxide transmission group finding is noteworthy. Furthermore, a dipping time analysis reveals that a 15-minute duration is optimal for achieving a 0.146 % photoelectric conversion efficiency in DSSCs utilizing CCE.

Exploring the interaction between derivatives of urea with resorcinol-based acridinedione dyes by employing fluorescence methods and molecular docking approach

Akyl urea derivatives, either symmetrical or unsymmetrical in nature possessing a free N-H or N-alkyl moieties in the molecular framework of urea governs the excited state properties of acridinedione dye (ADR1) which is a resorcinol-based derivative. Fluorescence enhancement (FE) of ADR1 dye is observed on the addition of unsymmetrical urea derivatives, whereas a decrease in the fluorescence intensity resulted upon the addition of symmetrical urea derivatives. The nature of the urea derivatives controls the suppression of photoinduced electron transfer (PET) via space, which is the cause of the FE. FQ results from the donor and acceptor moieties of ADR1 dye promoting the PET process. Urea (U), symmetrical and unsymmetrical urea derivatives (except Tetramethyl urea (TMU)) results no significant shift of the localized excited (LE) state emission of ADR1 dye. Studies of the ADR1 dye’s fluorescence lifetime in the presence of urea compounds show a significant increase in lifetime. This phenomenon is explained by a significant difference in the hydrogen-bonding (HB) pattern, which causes variationin the microenvironment created by thesolute molecules in the aqueous phase. Both the hydrophobic effects of the alkyl group substituents in the urea molecular framework and the HB interactions between the solute and solvent influence the excited state features of ADR1 dye. Further, the role of urea derivatives and ADR1 dye (both are considered as competitive guest molecules) energetics and molecular interactions were studied in the presence of host molecule, Human Serum Albumin (HSA). The binding energy (BE) and several bimolecular interactions driven by urea derivatives in the presence of ADR1-HSA complex in comparison with that of urea derivatives-HSA complex were investigated by molecular docking (Mol.Doc) methodology. Incorporating theoretical research along withsteady state and time-resolved fluorescence investigations proved to be an effective method to evaluate the interactions of competing solutes comprising bothhydrophobic and HB functional groups.

Removal of Dyes from Waste Water Using Low‐Cost Adsorbents

AbstractThe principal objective of this article is a thorough analysis of the usage of inexpensive adsorbents to eliminate dyes from different aquatic environments. Dyes, commonly employed in industries—textiles, pharmaceuticals, and food, pose a significant environmental concern due to their persistence and potential toxicity. In response, researchers have explored the efficacy of low‐cost adsorbents (LCAs) as sustainable and economical alternatives for dye elimination. An overview of the environmental effects of dye contamination and the difficulties in using traditional dye removal techniques is given at the outset of the paper. It then delves into the diverse range of LCAs, including agricultural by‐products, waste materials, and natural substances, that have shown promise in adsorbing and eliminating dye contaminants. Examples of such adsorbents include activated carbon (AC) derived from agricultural residues, bio‐adsorbents from various plant materials, and industrial by‐products with inherent adsorption properties. Key mechanisms involved in the adsorption process, such as surface chemistry, pore structure, and electrostatic interactions, are elucidated to offer a fundamental understanding of the sorption capabilities of these materials. This comprehensive review consolidates the current knowledge on dye removal utilizing LCAs, offering insights into the challenges, advancements, and future directions in this environmentally significant field. The findings underscore the potential of harnessing readily available, sustainable materials as effective sorbents for mitigating the adverse impacts of dye pollutants in aqueous systems. The adsorption capacity is comparable to supplementary adsorbents suggested for the removal of dyes. The widely accessible adsorption properties of basic and acidic dyes do not significantly differ from one another.

Synthesis and investigation of photo-physical properties of fluorescent dyes obtained by the Knoevenagel condensation of mono-, di- or tri-formyl aromatic aldehydes and various CH-acid derivatives

Fluorescent dyes were constructed using the Knoevenagel condensation of the appropriate aldehydes and CH-acid derivatives. Aromatic aldehydes containing one, two or three formyl groups were used as substrates. Cyanoacetamide, ethyl cyanoacetate, benzoylacetonitrile and indan-1,3-dione play the role of CH-acid derivative. The appropriate aldehydes were obtained by the Duff formylation reaction. The dyes synthesis procedure was very simple. The condensation was carried out in water in the presence of NaOH, as the basic catalyst at room temperature, and the dyes were obtained in yields between 58-93%. The work-up procedure was very simple, and the products do not require any further purification. The great advantages of this synthetic procedure are its simplicity, cheapness, compliance with the rules of green chemistry and the fact that it efficiently leads to structurally complex fluorescent dyes. Twenty-three new compounds were obtained, eleven of which exhibited fluorescence in solution and four in the solid state. Taking into account the fluorescence quantum yield and the emission maximum value close to the NIR range, the dye constructed by condensation of indan-1,3-dione and methyl 3,5-diformyl-4-hydroxybenzoate meets the above-mentioned requirements (Φ=16%, λem= 660 nm) best. The dye with the highest value of Φ = 25% in solid is a derivative of cyanoacetamide and 3,4,5-trimethoxybenzaldehyde.