ELEMENTARY ANALYSIS OF PHTHALOTCYAN PIGMENT CONTAINING COPPER, NITROGEN AND SULFUR

ABSTRACT

In this paper are studied the synthesis of high-intensity phthalocyanine pigments based on copper, nitrogen, and sulfur at a high temperature of 243 °C and the elemental analysis of pigment. According to results, high-content phthalocyanine pigments are included only in plasma and varnish coatings in an amount of 1-3% of the total mass. Phthalocyanine metal complexes have proven themselves to be effective markers for elements of optical devices and electronic systems, stable dyes, sensitizers, and, finally, highly selective catalysts. Such widespread use is associated with the specificity and uniqueness of the properties of compounds of this class, which is determined by their structure.

АННОТАЦИЯ

В статье изучен синтез высокоинтенсивного фталоцианинового пигмента с добавкой меди, азота и серы при высокой температуре 243 °С и элементный анализ полученного пигмента. Полученные фталоцианиновые пигменты с высоким содержанием включаются только в плазменные и лаковые покрытия в количестве 1-3% от общей массы. Фталоцианиновые металлокомплексы зарекомендовали себя как эффективные маркеры элементов оптических приборов и электронных систем, стабильные красители, сенсибилизаторы и, наконец, высокоселективные катализаторы. Столь широкое использование связано со специфичностью и уникальностью свойств соединений этого класса, которые, в свою очередь, определяются их строением.

Keywords: Phthalocyanine pigment, elemental analysis, copper salts, phthalic anhydride, sulfur compounds, intensity.

Ключевые слова: Фталоцианиновый пигмент, элементный анализ, соли меди, фталевый ангидрид, соединения серы, интенсивность.

Introduction

Phthalocyanines are used as traditional pigments and dyes for natural and synthetic fibers, paints, coatings, plastics are a popular class of functional dyes and as catalysts for various chemical reactions, materials for nonlinear optics, components of solar batteries, dyes for liquid crystal displays, photosensitizers for photodynamic therapy of cancer and other diseases [1,2] etc.

The demand for phthalocyanines is explained, on the one hand, by the relative ease of their preparation, and on the other, by a unique combination of physicochemical properties: intense absorption in the visible and near-IR spectral regions, high thermal, chemical, and photostability[3].

Unsubstituted phthalocyanines are insoluble in most solvents, except some polar aprotic solvents at elevated temperatures and concentrated sulfuric acid. Solubility in various media is achieved by introducing substituents into the macrocycle or by using axial ligands bonded to the metal atom.

The introduction of ionogenic groups (carboxy-, sulfo-, phosphonate) as substituents makes it possible to obtain compounds soluble in aqueous media, which is extremely important for use in medicine, in particular in photodynamic and catalytic therapy of oncological diseases.

The presence of carboxyl substituents provides a convenient opportunity for further functionalization of the molecule, including the preparation of conjugates of phthalocyanine complexes with natural or synthetic molecules [4].

Synthetic tetrapyrrole compounds, such as phthalocyanines (Fig. 1), have been proposed as convenient molecular models for studying the physicochemical properties of naturally occurring tetrapyrrole macrocycles, in part due to their structural similarity. However, due to their higher stability, better spectral characteristics, diverse coordination properties, and architectural flexibility, phthalocyanines are superior to porphyrins in several applications, and their enormous potential in various fields makes them one of the most studied macrocyclic and coordination compounds.

Figure 1. Basic phthalocyanine macrocycle

In the 1900s, phthalocyanines were widely used as dyes and pigments in the paint, printing, textile, and paper industries due to their vibrant blue-green color, photostability, insolubility in most solvents, and chemical inertness. For example, copper phthalocyanine is by far the most widely used synthetic dye. Phthalocyanines are also used as catalysts in many chemical reactions [5]. For example, phthalocyanine is the only tetrapyrrole compound used as an industrial catalyst for the oxidation of sulfur compounds in gasoline fractions [6.]. Recently, phthalocyanines have found wide application in such high-tech technologies as photo printing, the production of chemical sensors, electrochromism, molecular metals, liquid crystals, films Langmuir-Blodgett, semiconductors, and also as photosensitizers for photodynamic therapy [7]. The potential for such widespread use of phthalocyanines is due to their high degree of aromaticity, unique chemical structure, and electronic spectra.

It is well known that phthalocyanines are poorly soluble in water, which is due to the hydrophobicity of the aromatic core and the flat structure of the molecule. Solubility in most general organic solvents such as sulfolane, dimethyl sulfoxide (DMSO), and tetrahydrofuran is low, less than 1% by weight. To increase solubility, several functional groups are added to the benzene rings at the periphery of these macrocycles[8]. The physical, chemical, and electronic properties of phthalocyanines can also be adjusted by adding suitable substituents and functional groups to the molecule. One example of creating a soluble form of phthalocyanines is the sulfonation of phthalocyanine, which can be achieved by heating the phthalocyanine macrocycle in oleum (20-30% solution of sulfuric anhydride SO3) [9]..

Novelty of the work

A highly intensive organic phthalocyanine pigment was synthesized based on the chemical reaction of phthalic anhydride, urea, nitrogen, sulfur, and metal salts.

Materials and Methods

Most global manufacturers producers are based on copper phthalocyanine CuPc by heating to 200°C with phthalic anhydride, urea, copper chloride, and a catalyst (usually ammonium molybdate or molybdenum oxide) in a high boiling point (>180°C) solvent (often paraffin, trichlorobenzene or nitrobenzene). The highly exothermic reaction to form the aromatic macrocycle takes from 2 to 8 hours with yields of up to 90%. This process can be carried out without a solvent: “dry cracking” of the same components at a temperature of 200-300 °C, this reaction is faster, environmentally friendly,, and technologically advanced since the resulting pigment is additive (with a high concentration of acids) and requires purification.

Here are the methods of obtaining highly intensive phthalocyanine pigment containing copper, nitrogen, and sulfur. We study the processes of synthesizing copper phthalate pigment with a new composition. To obtain phthalocyanines, the highly purified pathogen is used as phthalonitrile, which also contains enough nitrogen atoms to form a macrocycle. As with phthalic anhydride, the process can be carried out using a homogeneous catalyst in a solvent medium or using the same catalysts using the fusion method. The peculiarity of this method is the formation of partially chlorinated CuPc (when copper chlorides are used as a source of metal ions) along with the main product, but the stable α-form pigment can be resistant to phase transitions. Chlorinated for the presence of ammonia or urea salts. Due to the shortage of phthalonitrile, the industrial production of phthalocyanine pigments is limited. 14 g of copper sulfate, 56 g of ammonium sulfate, 60 g of urea, and 15 g of phthalimide, adding a catalyst in the amount of 1% relative to the mass of phthalimide in a special vessel made of material resistant to the effects of concentrated acid and high temperature with a capacity of 250 ml. Mix in HP-550-S heating oven at high temperature for 40-50 minutes until homogenous (light air color). The homogeneous mixture is heated to 243 °C in a heating oven (SNOL brand) for 3 hours. The reaction lasted for 3 hours. Then the resulting powdery reaction mixture is cooled to 50 °C and dissolved in 85% concentrated sulfuric acid. Boiled water is added to the melted product and mixed. In this, various unreacted intermediate products dissolve. The resulting CuPc pigment precipitates. Precipitated phthalocyanine pigment is filtered in a Buechner funnel and washed several times with distilled water. The washed product is dried in the ShS-8001 ShSU oven. The yield of the obtained product is 86%.

Results and Discussion

In Fig.2 shows the elemental analysis of the obtained sample.

Figure 2. Elemental analysis of the synthesized CuSPc phthalocyanine pigment

Elemental analysis SEM-EDA- Using electron beams (in electron microscopes) or X-rays (in X-ray fluorescence analyzers), the atoms of the sample under study are excited and emit X-rays characteristic of each chemical element. By studying the energy spectrum of such radiation, one can conclude the qualitative and quantitative composition of the sample. Energy-dispersive X-ray spectroscopy can be used to examine objects in a scanning electron microscope or transmission electron microscope, where the object is examined using focused beams of high-energy electrons. A high vacuum (10-7 bar) is created in the microscope chamber to minimize the interaction of electrons with air molecules. The X-ray detector requires cooling, which is usually provided by a liquid nitrogen wall or a Peltier effect device. When an electron microscope operates, an electron beam leaves a source—an electron gun—and is accelerated by high voltage. When hitting an object, some of the electrons are scattered depending on the serial number of the element and its environment in the crystal structure; some excite the atoms of the object’s substance and cause characteristic radiation. Its composition is further studied by analyzing the energy spectrum of X-ray radiation caused by the interaction of electron beams and object atoms using an electron microscope detector (Si crystals with Li impurities). Analysis of individual maxima of the X-ray spectrum by their location (one wavelength of the maximum emission of a certain element) and intensity is also carried out by the appropriate method of wave-dispersive X-ray spectroscopy (WDS). an order of magnitude higher sensitivity and lower spectral resolution.

Based on the results of the analysis, the elemental analysis of the samples was presented in table-1.

Table 1.

The analysis results

Conclusion

it can be said that the methods of synthesizing a complex dye pigment containing nitrogen, sulfur, copper, and phthalic groups have been presented. High temperature is important in the synthesis of organic dyes, the intensity of pigments obtained at high temperature is high, but the yield of the obtained pigment decreases. The newly synthesized pigment allows the domestic market to high-intensity local raw materials and obtain import substitute products. The presence of 7.37% Cu, 17.35% N2,, and 2.9% S elements in the obtained pigment was studied using modern physical and chemical analysis methods.

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