Chemical Structure Of Dyes Research Articles

Plasma catalysis. A study of the influence of oxysulfur, SOx• species through the degradation of sulfonated dyes by non-thermal plasma

This work studied the degradation reaction of sulfonated dyes, indigo carmine, phenol red, and their mixtures by non-thermal plasma (NTP). Interestingly, the degradation rate constant showed a faster process and lower activation energy (Ea) for the dye mixtures than for the degradation reaction of the individual dyes. This unexpected result opened up new opportunities for understanding plasma chemistry and the interaction between reactive species formed by the plasma and the target molecule. As no catalyst or chemical additive was added to the reactor, the decrease in Ea came from a self-synergistic effect (SSE), through the dye molecules fragmentation, which resulted in plasma catalysis. The hypothesis proposed in this work is that oxysulfur (SOx) species are formed by the desulfonation reaction of dyes. The sulfonic groups (SO3) present in the chemical structures of dyes can function as precursors for forming several SOx•– species. Studies based on oxygenated sulfonated species such as SO3•–, SO4•– and SO5•– have been widely applied in advanced oxidative and reductive processes due to their satisfactory efficiency and low cost. Among them, SO4•– is the key reactive species with the best performance in the degradation of pollutants due to its high oxidation potential (E° = 2.60 V). In addition, it is an alternative source of HO• in aqueous media, improving the oxidation reaction. In order to elucidate the SSE, the kinetic process was followed by UV–Vis analysis, and the reactive species, such as alkyl, hydroxyl, and oxy-sulfur radicals were identified by Electron Paramagnetic Resonance. The by-products of the NTP degradation reaction were analyzed by ultrafast liquid chromatography coupled with a mass spectrometer, and a fragmentation route was proposed.

A novel bioflocculant extracted from excess-activated sludge for dye-containing wastewater treatment

Textile dyes are a major environmental concern related to the textile industry field due to their chemical complexity that hampers biodegradability and constraints conventional wastewater treatment. In this context, this work presents a bioflocculant produced from textile industry excess-activated sludge capable of precipitating azo dyes. The alkaline hydrolysis employed on dried activated sludge was optimized and the produced bioflocculant was characterized in terms of chemical composition, SEM-EDX, TEM, XRF, AAS, and TGA. The resulting flocculant presented 27 % protein, 12 % carbohydrate, and 12 % lipid contents, with hydroxyl and aliphatic CH functional groups. The chemical structure of dyes, the pH, and the respective zeta potential of the flocculating medium were taken into consideration during assays to conclude the flocculation mechanism. Flocculation assays resulted in color removal outcomes of 91 and 100 % for reactive and disperse dyes, respectively, at pH 5, and the OECD 301A biodegradability test confirmed the low presence of cellular debris after treatment. The activity of the bioflocculant was evaluated with a commercial naphthalene-based dispersant and the results were compared to color removal promoted by polyaluminum chloride (PAC). This work shows the feasibility of the low-cost activated sludge as a bioflocculant source and its potential in clarifying wastewater with azo dyes.

Photoelectrochemical Hydrogen Production by a Cobalt Tetrapyridyl Catalyst Using Push–Pull Dye‐Sensitized NiO Photocathodes

Herein, the synthesis and optoelectronic properties of a novel push–pull organic dye, pRK1, specifically designed for use in dye‐sensitized photocathodes for hydrogen generation, are reported. The chemical structure of this dye, which incorporates a benzothiadiazole moiety, is inspired by RK1, a dye previously reported as a photosensitizer in n‐type dye‐sensitized solar cells (DSSCs) with power conversion efficiencies above 10% and high stability. The photoelectrochemical activity for hydrogen evolution of pRK1 after grafting onto NiO photocathodes in combination with a cobalt tetrapyridyl catalyst [Co(bapbpy)(OH2)2](BF4)2 in aqueous solution is evaluated and compared with two reference dyes from the literature, RuP2‐bpy and P1. It is shown that among the three photocathodes studied in this work, NiO|pRK1 is the most efficient, producing up to 1.9 μmol cm−2 of hydrogen with a faradaic efficiency of 66%, under visible light irradiation in aqueous electrolyte at pH 4.5. pRK1 shows a turnover number (TONdye) of up to 145 during the 6 h chronoamperometric test, almost twice that of P1. This study demonstrates that the chemical structure of high performance dyes commonly used in DSSCs can be successfully modified to meet the requirements for light‐driven water splitting in dye‐sensitized photoelectrochemical cells.

Photo-Assisted Removal of Rhodamine B and Nile Blue Dyes from Water Using CuO-SiO2 Composite.

Wastewater from the textile industries contaminates the natural water and affects the aquatic environment, soil fertility and biological ecosystem through discharge of different hazardous effluents. Therefore, it is essential to remove such dissolved toxic materials from water by applying more efficient techniques. We performed a comparative study on the removal of rhodamine B (RhB) and Nile blue (NB) from water through a catalytic/photocatalytic approach while using a CuO–SiO2 based nanocomposite. The CuO–SiO2 nanocomposite was synthesized through a sol–gel process using copper nitrate dihydrate and tetraethylorthosilicate as CuO and SiO2 precursors, respectively, with ammonia solution as the precipitating agent. The synthesized nanocomposites were characterized, for their structure, morphology, crystallinity, stability, surface area, pore size and pore volume, by using a scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET) techniques. The CuO–SiO2 nanocomposite was used for potential environmental applications in the terms of its catalytic and photocatalytic activities toward the degradation of rhodamine B (RhB) and Nile blue (NB) dyes, in the presence and absence of light, while monitoring the degradation process of dyes by UV-Visible spectroscopy. The catalytic efficiency of the same composite was studied and discussed in terms of changes in the chemical structures of dyes and other experimental conditions, such as the presence and absence of light. Moreover, the composite showed 85% and 90% efficiency towards the removal of rhodamine B and Nile blue dyes respectively. Thus, the CuO–SiO2 nanocomposite showed better efficiency toward removal of Nile blue as compared to rhodamine B dye while keeping other experimental variables constant. This can be attributed to the structure–property relationships and compatibility of a catalyst with the molecular structures of dyes.

Organelle-selective near-infrared fluorescent probes for intracellular microenvironment labeling

The design, synthesis, and bio-applicability of a series of 8 near-infrared (NIR) molecular probes with tunable hydrophilic/hydrophobic properties are described in this paper. The title dyes comprise of symmetric heptamethine cyanines with various N-quaternary heterocyclic moieties including indole, benzo[e]indol, benzothiazole and naphtho[1,2-d]thiazole, along with an extra positive charge in close proximity to the polymethine backbone. Combined UV–Vis and spectrofluorimetric techniques in both organic and aqueous-buffered solutions were employed to investigate the optical properties of the NIR chromophores. Two of the fluorophores emerged remarkable fluorescence quantum yield (Φ = 0.083), while their brightness was found up to 3-fold that of the FDA approved Indocyanine green – ICG (Φ = 0.027). What is more, two of the dyes appear to outperform the later clinical benchmark fluorophore in terms of photostability. While the ICG was completely faded after 1 h of constant irradiation, nearly 70% of the original emission signal could be observed for one of the novel molecular probes. The log Pow values determined by a combination of HPLC and UV–Vis (partition between 1-octanol/water) cover a relatively large range, from −2.14 up to 7.92. Investigation on the cytotoxicity by means of the MTT assay revealed, that present dyes are suitable for bioanalytical purposes and are safe to use. This paper also includes fluorescence imaging and cellular applications, such as labeling of HeLa cervical cancer cells. The results from the confocal microscopy reveal the superior staining capability of current heptamethines since they show significantly brighter signal than the commercial ICG probe. An organelle-selective fluorescent staining was achieved depending on the dye chemical structure. Co-localization within the intracellular microenvironment (linear or granular - cytosol, mitochondria, lysosome, endoplasmatic reticulum or Golgi apparatus) was confirmed without interference, employing several conventional organelle dye trackers. To the best of our knowledge, heptamethine dyes represent the first example of a series NIR emitting probes, that exhibit rational structural modifications aiming to fine-tune the hydrophilic/hydrophobic properties furnishing organelle-targeted staining.

Impact of fluorescent dyes on the physicochemical parameters of microbubbles stabilized by albumin-dye complex

Gas-filled microbubbles are routinely used as ultrasound contrast agents in the clinic. Recently, microbubbles attracted attention as agents for multimodal imaging and image-guided drug delivery. Hence, we prepared microbubbles based on albumin-dye complexes to achieve optimal bimodal (fluorescent/ultrasound) imaging properties. The fluorescent dyes used for in vitro/in vivo/medical imaging (Fluorescein, and Rhodamine B, Cyanine 5.5, and Cyanine 7, Indocyanine Green) were introduced into the albumin-dye complex structure. Interconnections between dyes parameters (chemical structure, molecular weight, and hydrophobicity), properties of albumin-dye complexes (type of bond and ratio between protein and dye, solution surface tension), and bimodal agent properties (concentration, mean size, storage stability) were evaluated. Bimodal imaging of "colored" microbubbles was assessed using ultrasound with 33, 50 MHz frequencies and fluorescence tomography. We observed that the ratio between the protein molecules and the protein-dye complex in the microbubble shell was approximately equal, highlighting the impact of dye chemical structure on albumin-dye complex properties and resulting microbubble properties in characterization and imaging. These findings shed light on correlations between microbubble interface stabilization with albumin, microbubble structure formed by albumin-dye complexes, physicochemical properties and applications of bimodal (fluorescent/ultrasound) contrast agents.

Synthesis of magnetic Fe3O4/activated carbon prepared from banana peel (BPAC@Fe3O4) and salvia seed (SSAC@Fe3O4) and applications in the adsorption of Basic Blue 41 textile dye from aqueous solutions

Textile industries use large amounts of water and chemicals for finishing and dying processes. The chemical structures of dyes vary enormously, and some have complicated aromatic structures that resist degradation in conventional wastewater treatment processes because of their stability to sunlight, oxidizing agents, and microorganisms. The objective of this research is to compare the adsorption efficiency of two types of magnetic activated carbons derived from Banana peel and Salvia seed for the removal of basic blue 41 dye. The faculty of the produced activated carbons to remove basic blue 41 dye from aqueous solutions via batch adsorption has been examined under several operating conditions such as pH, adsorbent dose, initial adsorbate concentration and contact time. The cheap, non-toxic produced activated carbons (AC) were characterized by scanning electron microscope and Brunauer-Emmett-Teller analyses. The best conditions of dye adsorption with BPAC@ Fe3O4 equal to pH = 9, AC dose 0.5 g/L , dye concentration 50 mg/L and equilibrium contact time 30 min, optimal dye adsorption conditions for SSAC@Fe3O4 equal to pH = 9, adsorbent dose 0.75 mg/L , dye concentration 50 mg/L and equilibrium contact time is 30 min. This study followed the Langmuir isotherm model well with regression coefficient of R2= 0.9886 for BPAC@Fe3O4 and regression coefficient of R2= 0.9764 for SSAC@Fe3O4.

A NOVEL APPROACH FOR OXIDATIVE DEGRADATION OF SOME ANIONIC AZO DYES BY ALKALINE HEXACYANOFERRATE (III) ION

The degradation of anionic azo dye via Hexacyanoferrate (III) ions (oxidant) in the aqueous alkaline medium has been investigated through kinetic–spectrophotometric technique. The efficiency of this treatment strongly depends on the chemical structure of dyes. The effect on the reaction of various parameters (concentration of dyes, oxidant, and pH solution) has been examined. The degradation of acid red 27, acid yellow 23, and azo violet dyes follow the first-order kinetic model concerning [HCF (III)] and [Dye]. The degradation rates of dyes follow the order: acid red 27> acid yellow 23> azo violet. The successive products of the dyes reveal that the dyes are effectively oxidized via HCF (III) in aqueous alkaline medium. Thermodynamic parameters of acid red 27 dyes at four different temperatures ranging between 40 to 55 ºC reveal that the degradation rate of acid red 27 dye is much better from azo violet, acid yellow 23.

Complete separation of colorants from polymeric materials for cost-effective recycling of waste textiles

Currently, only 1% of waste textiles, mainly whites, are recycled because dyes on fibers caused various problems. Unseparated colors might sublime during the fiber regeneration process and pollute the working environment. More seriously, final color quality of regenerated fibers is uncontrollable. Technologies for complete color removal from waste textiles either by dye-destruction or extraction have major challenges impeding their industrialization. Dye-destruction damages polymers, changes dyeability of regenerated textiles, and pollutes the environment. Since the differences in solubility parameters between polymers and dyes are large, and dye extractions focuses on finding solvents with high dye solubility, dye-extraction fails to remove all dyes from textiles. Finding solvents is almost impossible to lower the chemical potential of dyes in solutions than that in fibers where dyes are accessible, and polymers are tightly arranged. Lessening fiber density substantially disrupts physical interactions between dyes and fibers, and thus raises chemical potential of dyes in all parts of fibers higher than that in solutions, although reducing fiber density might increase the chemical potential of dyes in solvents. Here we demonstrate that minimization of fiber density by solvents and temperatures completely removes disperse dyes, acid dyes and direct dyes from polyethylene terephthalate, nylon and cotton fibers, respectively. The chemical structures of dyes and average molecular weight polymers did not change after dye removal.

Effect of mechanical treatments on orientation behavior and spectral properties of azoderivative dyes incorporated in poly(vinyl alcohol) films

AbstractVarious azoderivative dyes were incorporated in uncolored poly(vinyl alcohol) (PVOH). One type of film was obtained by drying the layer of solution cast on glass plate. The other type was obtained by rubbing the PVOH layer before complete drying. Linear birefringence and dichroism of dyed polymer films were investigated as a function of stretching degree. An increase in the linear birefringence was found with increasing stretching degree for both uncolored and colored films. Dichroism of the PVOH films depends on the dye chemical structure and also on the stretching degree of both non‐rubbed and rubbed and dyed PVOH samples. Molecular modeling was used to examine interactions occurring between PVOH and the embedded dye molecule. These stretching degree dependencies were approximated mathematically, which was used to describe the behavior of some components of interference filters.

Molecular and Spectroscopic Characterization of Green and Red Cyanine Fluorophores from the Alexa Fluor and AF Series.

The front cover artwork was provided by Gabriel Moya, a PhD student in the Cordes lab (LMU Biocenter Munich, Germany). The cover image shows an artistic impression of the chemical structures of two fluorophores investigated in the paper. Read the full text of the Article at 10.1002/cphc.202000935.

Biotreatment of sulfonated dyestuffs with energy recovery in microbial fuel cell: Influencing parameters, kinetics, degradation pathways, mechanisms, and phytotoxicity assessment

Removal of recalcitrant sulfonated dyestuff intermediates from wastewater has been an urgent challenge for environmental technologies. In this regard, the biodegradations of monoazo Methyl Orange (MO) and diazo dyes Reactive Black 5 (RB5) towards wastewater treatment and bioelectricity generation in microbial fuel cell were investigated and compared through the studies on azo dye concentration, aeration, sampling points arrays, and electrode spacings. The degradation of diazo RB5 yielded higher chemical oxygen demand removal, decolourization efficiencies, and power generation over monoazo MO. The decolourization efficiency of RB5 (97.62%) increased with an increase of RB5 concentration (50 mg/L), suggesting that the system has the capability of removing higher RB5 concentration. However, contrary results were obtained with MO due to its toxicity. This study also demonstrated that the decolourization rate of diazo RB5 (0.1533 h−1) was ≈ 53% higher than monoazo MO (0.0727 h−1). The findings revealed that the degradation kinetic was remarkably influenced by the chemical structure of dye, where dye with more electron-withdrawing groups at para position are more susceptible to be reduced. Higher output voltage (568.59 mV) and power generation (108.87 mW/m2) were attained with RB5 due to electron donor availability and electron-shuttling characteristics of RB5 decolourized intermediates. Furthermore, detailed degradation pathways of MO and RB5 were presented based on the UV–vis and GC-MS results. The phytotoxicity assessment via Sorghum bicolor seeds had further verified the reduction in toxicity after the treatment of azo dyes.

Evaluation of toxicity and mutagenicity of a synthetic effluent containing azo dye after Advanced Oxidation Process treatment

Approximately 20% industrial water pollution comes from textile dyeing process, with Azo dyes being a major problem in this scenario and requiring new forms of efficient treatment. Effluent treatments using the Advanced Oxidation Processes (AOP) are justified by the potential of application in the dyed effluent treatments once they can change the Azo dye chemical structure. Thus, this study aimed to evaluate the toxicity and mutagenic capacity of a synthetic effluent containing Amido Black 10B (AB10B) azo dye before treatment with AOP, named Gross Synthetic Effluent (GSE), and after the AOP, named Treated Synthetic Effluent (TSE). Daphnia magna and Allium cepa tests were used to evaluate acute toxicity effects and chromosomal mutagenesis, respectively. The Salmonella/microsome assay was performed to evaluate gene mutations. In silico assays were also performed aiming to identify the mutagenic and carcinogenic potential of the degradation byproducts of AB10B. There was 100% immobility to D. magna after 24 h and 48 h of treatments with TSE, showing EC50 values around 5%, whereas GSE did not show acute toxicity. However, GSE induced chromosomal mutations in A. cepa test. Both GSE and TSE were not able to induce gene mutations in S. typhimurium strains. These effects can be associated with two byproducts generated with the cleavage of the azo bonds of AB10B, 4-nitroaniline and -2-7-triamino-8-hydroxy-3-6-naphthalinedisulfate (TAHNDS). In conclusion, AOP is an efficient method to reduce the mutagenicity of synthetic effluent containing AB10B and additional methods should be applied aiming to reduce the toxicity.

Near-infrared pH responsive heptamethine cyanine platforms: Modulating the proton acceptor

In this report, we wish to present the rational design, synthesis, and study of optical characteristics of near-infrared (NIR) molecular probes emitting over 800 nm. The title pH sensing platforms consist of a piperazine moiety serving as a hydronium ion receptor, coupled with a rigidified symmetric heptamethine backbone. The spectrally fine-tuned response of the fluorophores was studied in both organic solvents and aqueous buffer solutions, employing combined UV–Vis and steady state fluorimetric techniques. In parallel, computational approach and optical spectroscopy were employed aiming to ascribe the origin of spectral behavior of the amino-substituted heptamethines. Herein, we also investigated the halochromic effect of the differently substituted piperazines on the spectral properties of the NIR cyanine dyes. Under acidic conditions, the protonation of the piperazine moiety promoted a gradual bathochromic shift in the absorption spectra. The Δλ between the neutral and the protonated forms are indirectly related to the modifications applied to the proton acceptor. The calculated pKa values (5.13–7.06) were found to be dependent on the dye chemical structure. A good linear correlation was established between the pKa of the newly synthesized dyes and that of the reported piperazine moieties. This aspect allows the future expansion of the current facile strategy since sensing chromophores with predicted pH response could readily be designed based on pKa databases for substituted piperazine derivatives. A detailed literature study along with NMR and computational methods were found to be in agreement with our assumption, that both nitrogen atoms of the 1,4-disubstituted amine are involved in the sensing process. The covered pKa range allows us to recommend the title fluorophores as promising potential candidates for qualitative analysis of biological samples. A cytotoxicity study by the MTT assay showed that the NIR dyes are safe and applicable for bioanalytical purposes at dye concentrations up to 10 μM. Fluorescence imaging and cellular applications, including staining and visualization of HeLa cervical cancer cells was successfully demonstrated.

Novel hydrazono-hydrazonoyl chlorides containing pyrazole moiety for concurrent dyeing and practical finishing of cotton fabrics

Four 2-(2-(5-(4-Methoxyphenyl)-1-phenyl-1H-pyrazole-3-carbonyl) hydrazono)-N’-arylpropanehydrazonoyl chlorides were designed outset from 4-methoxyaceteophenone, as raw matter, by interacting of carbohydrazide with four hydrazonoyl chloride derivatives in refluxing ethanol. The synthesized heterocycles stone was depicted and utilized through simple concern finishing as azo dyes for coloring and functionalization of cotton fabric. The outcomes obtained disclosed that the finishing treatments improved the nitrogen percent as well as wrinkle recovery angles along with a modicum decreasing in the tensile strength of treated fabric samples compared with the untreated fabric. The results assured also the perfect color fastness properties of the dyed samples, irrespective of the dye chemical structure. Besides, such dyes improved the treated fabric antibacterial properties as well as protection against the deleterious sun radiation. After 15 washing cycles, the dyed/finished samples exhibited satisfactory color strength and acceptable functional properties confirming stability and the tight binding of such dyes to the fabric chemical structure. Otherwise, both the untreated and treated textiles were recognized by means of scan electron microscope that signalizes hunting of such dyes by the cotton fabric structure.

Non-cytotoxic photostable monomethine cyanine platforms: Combined paradigm of nucleic acid staining and in vivo imaging

Cyanine based chemosensing platforms have successfully been employed over the past couple of decades in various fields of biomolecular sciences. Still a substantial number of recent advances and improvements on this class of compounds are reported in the art. This paper presents our latest work on the improved synthetic approach, study on photophysical properties, and biosensing applicability of monomethine cyanine dyes. The series of mono-, di- and tricationic dyes showed up to 5-fold enhanced resistance against photobleaching compared to the commercially available Thiazole Orange (TO). The title compounds were studied as potential molecular probes for the detection of deoxyribonucleic acid, demonstrating their capacity as excellent fluorescent labeling agents. Depending on the dye chemical structure, current Cl-TO compounds exhibit up to 834-fold enhanced fluorescence emission and form stable complexes with Calf Thymus-DNA. The calculated binding constants were found to be higher than several conventional fluorogenic dyes for nucleic acid detection. All studied derivatives appeared as less cytotoxic than the Thiazole Orange. IC50 concentrations in human fibroblasts MRC5 cell line were calculated up to 50 μM for the synthesized Cl-TO dyes, and 0.5 μM for the parental Thiazole Orange. Two of the dyes were found very competent in post-electrophoretic visualization of DNA. As demonstrated by the agarose gel electrophoresis, the staining efficiency and detection limits of the dyes were comparable to the widely used Ethidium Bromide. The tricationic dye revealed great potential for cell cycle analysis in G1, S and G2 phases. The chlorinated TO derivatives readily stain human cells in vivo, while they can effectively be applied for eukaryotic and microbial cell staining.

Olfactory Atlases with an Array of Porphyrinoids Coated ZnO Nanoparticle

Olfactory Atlases with an Array of Porphyrinoids Coated ZnO Nanoparticle

Sulfenic Acid-Directed Chemical Probes and Workflows for Assessing Protein Oxidation

Cyanine based chemosensing platforms have successfully been employed over the past couple of decades in various fields of biomolecular sciences. Still a substantial number of recent advances and improvements on this class of compounds are reported in the art. This paper presents our latest work on the improved synthetic approach, study on photophysical properties, and biosensing applicability of monomethine cyanine dyes. The series of mono-, di- and tricationic dyes showed up to 5-fold enhanced resistance against photobleaching compared to the commercially available Thiazole Orange (TO). The title compounds were studied as potential molecular probes for the detection of deoxyribonucleic acid, demonstrating their capacity as excellent fluorescent labeling agents. Depending on the dye chemical structure, current Cl-TO compounds exhibit up to 834-fold enhanced fluorescence emission and form stable complexes with Calf Thymus-DNA. The calculated binding constants were found to be higher than several conventional fluorogenic dyes for nucleic acid detection. All studied derivatives appeared as less cytotoxic than the Thiazole Orange. IC50 concentrations in human fibroblasts MRC5 cell line were calculated up to 50 μM for the synthesized Cl-TO dyes, and 0.5 μM for the parental Thiazole Orange. Two of the dyes were found very competent in post-electrophoretic visualization of DNA. As demonstrated by the agarose gel electrophoresis, the staining efficiency and detection limits of the dyes were comparable to the widely used Ethidium Bromide. The tricationic dye revealed great potential for cell cycle analysis in G1, S and G2 phases. The chlorinated TO derivatives readily stain human cells in vivo, while they can effectively be applied for eukaryotic and microbial cell staining.

Toward deposition of organic solid with controlled morphology on selected surfaces

Multilayer organic and inorganic systems of thin solid films are widely used in novel optoelectronic devices. The required properties of the system depend on the morphology of the films and transition zone at interfaces. We studied the formation of deposits of fluorinated azo-dyes, polymethine, merocyanine and sulfur-terminated organic compounds (STOC) by evaporation and condensation in vacuum. The films were deposited on glass, silicon (Si), gold (Au) and polytetrafluoroethylene (PTFE) substrates. The influence of dye chemical structure and substrate on deposit morphology was studied using atomic force microscopy (AFM). Depending on the ratio between thermodynamic and kinetic processes, islands, crystalline aggregates or nano-structures were obtained. A difference in the morphology of the same dye solid, but deposited on various substrates was detected. Changes in the dye end or side groups caused variation in the morphology of the dye solid film. STOC formed a smooth film on the Au surface, while on the glass and PTFE it formed various islands. Thin films of the dyes in PTFE matrix exhibited unique stability to action of external factors. A new type of evaporable dyes with unsaturated reactive bond at the end was synthesized. Using new evaporation–activation–polymerization methods, the films with enhanced hardness and thermal stability were prepared from new dyes. Several dyes formed nano-micro-wires during the self-assembly process, in some cases between two neighboring Au strips. Adjusting the structure of the molecule by changing the end groups allows purposeful control of the deposit morphology on the selected surface.

English

A preliminary study on the chemical structure of dyes from Rothmannia hispidia, Pterocarpus osun and Terminalia superba was made using chemical tests, UV-visible and infrared spectroscopies. R. hispidia dye was found to contain an alkyl amino group (-NHR) and carbon-carbon double bond conjugated with a carbonyl (C = O) group, and also showed maximum absorption at 595 nm in the visible region. P. osun dye contains conjugated systems, hydroxyl (-OH) and amino (NHR) groups and showed maximum absorption at 506 nm in the visible region whereas T. superba dye is made up of conjugated system, nitro (NO2) and hydroxyl (-OH) groups. It showed maximum absorption at 478 nm in the visible region. Key words: Rothmannia hispidia, Pterocarpus osun, Terminalia superba, dyes, characterization.