Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes

*Sharad Rohidas Patil and Amol S. Chaudhary*

## **Abstract**

This chapter provides a general overview and information on near-infrared (NIR) absorbing azo dyes. In this work, we have developed an efficient and simple protocol for the synthesis of novel A-π-D-π-A NIR azo dyes. The near-infrared absorbing azo dyes were synthesized by using 2-hydroxy-1,4 naphthoquinone (Lawsone) and different substituted aromatic primary amines. Furthermore, author developed push-pull chromophores of A-π-D-π-A type containing an electron-withdrawing azo core, phenazine moieties, and a hydroxyl group as electron donor. The benzo[a]quinoxalino[2,3-i]phenazin-5-ol moiety was introduced to make the system planer as well as to increase the π-conjugation. The optical properties of these dyes were studied in *N,N*-dimethylformamide (DMF).

**Keywords:** NIR absorbing azo dyes, 2-hydroxy-1,4-naphthoquinone, Lawsone, optical properties, phenazine core

## **1. Introduction**

In 1856, William Henry Perkin accidentally discovered the world's first commercially successful synthetic dye. Dyes are defined as colored organic or inorganic compounds, mixtures, complexes, or substances that once applied to the fibers/ substrate, it imparts a permanent color to the fibers/substrate. This is able to resist fading upon exposure to sweat, light, water, and many chemicals, including oxidizing agents and microbial attack. Over 10,000 synthetic dyes were developed and used in manufacturing by the end of the nineteenth century. Azo dyes are a class of compounds containing a *N=N* double bond and, due to their ability to absorb visible to near-infrared (NIR) light and ease of synthesis, they have been extensively used in the textile, fiber, leather, paint, and printing industries for more than a century. The azo group is substituted with benzene or naphthalene groups, which can contain many different substituents, such as chloro (–Cl), methyl (–CH3), nitro (–NO2), amino (–NH2), and hydroxyl (–OH), carboxyl (–COOH), which give different types of azo dyes. Azo dyes account for the majority (more than 3000 different varieties) of all textile dyestuffs produced because of the ease and cost-effectiveness of their synthesis, their stability, and the variety of colors available compared to natural dyes. They are extensively used in the textile, paper, food, leather, cosmetics, and pharmaceutical industries [1–3].

Azo colorant represents the greatest production volume in dyestuff chemistry due to simplicity of coupling reaction, adaption to the needs of most diverse applications such as textile dying, coloring of plastics and polymer, in liquid crystal displays (LCD), optical data storage, nonlinear optics, biological and medical field, and advanced application in organic synthesis [4–6]. Azo chromophores have versatile applicability ranging from textile dyeing [7], leather dyeing [8], coloring of plastics, and polymer [9] to advanced applications such as liquid crystal displays [10], biological and medical studies, and advanced application in the organic synthesis [11]. Also, they contribute greatest production volume of the dyestuff industry due to simplistic mode of their synthesis with high yield.

The infrared wavelength ranges of the electromagnetic spectrum cover the area between the visible region and the microwave region. The infrared radiation spectrum is generally accepted and can be subclassified into the near-, medium-, and far-infrared regions. An important challenge in creating molecules with desired optical properties lies in achieving a well-defined architecture while maintaining adequate electron density throughout the whole molecule [12]. Organic materials with intense absorptions in the near-IR region (i.e., 750–1300 nm) are particularly important in number of applications including thermal imaging, optical data storage, automatic identification, etc. NIR absorbing dyes have been attracting increasing interest due to the rapid progress achieved in their high technology applications.

In this region, infrared radiation provides sufficient energy to the NIR dyes, which impart a *π* → *π*\* transition of electrons within dye chromophore molecules. Despite the enormous synthetic versatility of azo dyes, which accounts for representing 50–70% of all commercially available dyes, little effort has been devoted to bring their absorption into the long wavelength region, and only a few examples of NIR absorbing azo dyes have till now been disclosed [13, 14]. Near-infrared absorbing dyes have attracted significant interest for their uses in the development of functional materials for high-technology end uses. Considerable interest is evinced in recent years in the design of near-infrared absorbing organic azo dyes. They find manifold applications in the high technology areas such as dye sensitized solar cells (DSSCs) [15], laser optical storage systems [16], clear coatings [17], organic

**249**

**Figure 3.**

*Structures of the dyes* **9–11***.*

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes*

photovoltaics [18], greenhouse claddings [19], molecular switches [20], NIR-active materials [21], colorimetric sensors [22], mesomorphic [23], solvatochromic [24–26], and electrochemical materials [27] and surface relief grating (SRG)-forming azo polymer films [28], laser-printing systems, laser filters, photography, photonics, and in telecommunication devices operating at wavelengths in the NIR region [29].

The planar structure of phenazine with a heterocyclic pyrazine nucleus and a fully conjugated aromatic π-system imparts to that special optical and redox properties. The optical properties give it functional for applications in molecular imaging as fluorescent tracers and stains for subcellular components and biological events. Highly electron-rich and redox-active molecules like phenazines might be functional for preparation of organic materials that includes donor-π-acceptor design. Pyrazine compounds are electron-deficient species. Hence, they are used in the design of n-type organic semiconductors; examples

*DOI: http://dx.doi.org/10.5772/intechopen.81229*

*Reported azo derivatives of lawsone (***6–8***).*

**Figure 2.**

**Figure 1.** *Chemical structure of pyrazinacenes for organic thin film transistors.*

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes DOI: http://dx.doi.org/10.5772/intechopen.81229*

**Figure 2.** *Reported azo derivatives of lawsone (***6–8***).*

*Chemistry and Technology of Natural and Synthetic Dyes and Pigments*

industry due to simplistic mode of their synthesis with high yield.

Azo colorant represents the greatest production volume in dyestuff chemistry

The infrared wavelength ranges of the electromagnetic spectrum cover the area between the visible region and the microwave region. The infrared radiation spectrum is generally accepted and can be subclassified into the near-, medium-, and far-infrared regions. An important challenge in creating molecules with desired optical properties lies in achieving a well-defined architecture while maintaining adequate electron density throughout the whole molecule [12]. Organic materials with intense absorptions in the near-IR region (i.e., 750–1300 nm) are particularly important in number of applications including thermal imaging, optical data storage, automatic identification, etc. NIR absorbing dyes have been attracting increasing interest due to the rapid progress achieved in their high technology applications. In this region, infrared radiation provides sufficient energy to the NIR dyes, which impart a *π* → *π*\* transition of electrons within dye chromophore molecules. Despite the enormous synthetic versatility of azo dyes, which accounts for representing 50–70% of all commercially available dyes, little effort has been devoted to bring their absorption into the long wavelength region, and only a few examples of NIR absorbing azo dyes have till now been disclosed [13, 14]. Near-infrared absorbing dyes have attracted significant interest for their uses in the development of functional materials for high-technology end uses. Considerable interest is evinced in recent years in the design of near-infrared absorbing organic azo dyes. They find manifold applications in the high technology areas such as dye sensitized solar cells (DSSCs) [15], laser optical storage systems [16], clear coatings [17], organic

due to simplicity of coupling reaction, adaption to the needs of most diverse applications such as textile dying, coloring of plastics and polymer, in liquid crystal displays (LCD), optical data storage, nonlinear optics, biological and medical field, and advanced application in organic synthesis [4–6]. Azo chromophores have versatile applicability ranging from textile dyeing [7], leather dyeing [8], coloring of plastics, and polymer [9] to advanced applications such as liquid crystal displays [10], biological and medical studies, and advanced application in the organic synthesis [11]. Also, they contribute greatest production volume of the dyestuff

**248**

**Figure 1.**

*Chemical structure of pyrazinacenes for organic thin film transistors.*

photovoltaics [18], greenhouse claddings [19], molecular switches [20], NIR-active materials [21], colorimetric sensors [22], mesomorphic [23], solvatochromic [24–26], and electrochemical materials [27] and surface relief grating (SRG)-forming azo polymer films [28], laser-printing systems, laser filters, photography, photonics, and in telecommunication devices operating at wavelengths in the NIR region [29].

The planar structure of phenazine with a heterocyclic pyrazine nucleus and a fully conjugated aromatic π-system imparts to that special optical and redox properties. The optical properties give it functional for applications in molecular imaging as fluorescent tracers and stains for subcellular components and biological events. Highly electron-rich and redox-active molecules like phenazines might be functional for preparation of organic materials that includes donor-π-acceptor design. Pyrazine compounds are electron-deficient species. Hence, they are used in the design of n-type organic semiconductors; examples

**Figure 3.** *Structures of the dyes* **9–11***.*

are pyrazinoquinoxaline derivatives, hexaazatriphenylenes, diquinoxalino, phenazine, and quinoxalinophenanthro phenazine [30]. Richards et al. have shown that pyrazinacenes are good candidates as materials for organic thin film transistors as shown in the **Figure 1** [31]. The existence of a donor-π-acceptor (D-π-A) alternating structure has been proved to be an efficient way to reduce band gap energies of conjugated molecules. The phenazine core consists of the electron-withdrawing pyrazine ring which might be an excellent charge acceptor.

Romanyuk et al. has reported azo derivatives of 2-hydroxy-1,4 naphthoquinones **5** as shown in **Figure 2** [32].

There are no further reports in the use of 2-hydroxy-1,4-naphthoquinone in the synthesis of azo colorants. It is known that the molecule with a quinoid fragment shows keto-enol tautomerism when a hydroxyl group is presenting adjacent to one of the quinoid carbonyl groups: the p-quinoid structure can transform into an *o*-quinoid or dihydro structure.

The reactions of 2-hydroxy-1,4-naphthoquinone in the synthesis of azo colorants for NIR-absorbing dyes have been explored in our previous work. Three different kinds of near-infrared (NIR) absorbing pull-push acceptor-π-donor-π-acceptor (A-π-D-π-A) V-shaped chromophoric dyes have been synthesized. These dyes are architect by doing substitution with 5-hydroxy and 6-arylazonium on the benzo[a] naphtho[2,3-h] phenazine dione core. Phenazine and anthraquinone moieties were envisaged in a single molecule with a view to enhance the photophysical properties in NIR region as shown in **Figure 3** [33].

This work is aimed at synthesizing novel molecules containing both phenazine and azo cores that were envisaged in a single molecule with a view to enhance the photophysical properties in the NIR region. In this study, we have extended our contribution to synthesis NIR absorbing dyes (**12–14**) as shown in **Figure 4**.

**251**

**Figure 5.**

*Schematic representation of NIR azo dyes (***12–14***).*

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes*

(**18–20)** and 2,3-diaminophenazine core (**21**) (**Figure 5**).

In the present study, the use of 2-hydroxy-1,4-naphthoquinone (Lawsone) **5** coupling components and diazo components in the synthesis of azo disperse dyes followed by condensation with *o*–phenylenediamine OPDA to obtain the desired

In this context, authors have extended our contribution to synthesis of three different kinds of near infrared (NIR) absorbing pull-push acceptor–π–donor–π acceptor (A–π–D–π–A) chromophoric dyes. The NIR absorbing dyes (**12–14**) were synthesized from derivatives of 2-hydroxy-3-(phenyldiazenyl)naphthalene-1,4-dione

The scaffold of phenazine, *N,N*-dimethylaniline, and anthraquinone moieties was envisaged in a single molecule with a view to enhance the photophysical properties in NIR region. The UV-Vis absorption spectra of synthesized azo-azine dyes have been studied. The intermolecular interaction occurring in solvents of differing polarities as well in solution of different pH have been studied. The structures of the dyes are given in **Figure 4**. Synthetic route for the dyes **44–46** and their intermedi-

*DOI: http://dx.doi.org/10.5772/intechopen.81229*

**2. Result and discussion**

NIR absorbing azo dyes (**12–14**).

ates are depicted in **Figure 5**.

**2.1 Synthesis strategy**

**Figure 4.** *Structures of the near-IR absorbing dyes (***12–14***).*

## **2. Result and discussion**

## **2.1 Synthesis strategy**

*Chemistry and Technology of Natural and Synthetic Dyes and Pigments*

are pyrazinoquinoxaline derivatives, hexaazatriphenylenes, diquinoxalino, phenazine, and quinoxalinophenanthro phenazine [30]. Richards et al. have shown that pyrazinacenes are good candidates as materials for organic thin film transistors as shown in the **Figure 1** [31]. The existence of a donor-π-acceptor (D-π-A) alternating structure has been proved to be an efficient way to reduce band gap energies of conjugated molecules. The phenazine core consists of the electron-withdrawing pyrazine ring which might be an excellent charge

Romanyuk et al. has reported azo derivatives of 2-hydroxy-1,4 naphthoquinones

There are no further reports in the use of 2-hydroxy-1,4-naphthoquinone in the synthesis of azo colorants. It is known that the molecule with a quinoid fragment shows keto-enol tautomerism when a hydroxyl group is presenting adjacent to one of the quinoid carbonyl groups: the p-quinoid structure can transform into an

The reactions of 2-hydroxy-1,4-naphthoquinone in the synthesis of azo colorants for NIR-absorbing dyes have been explored in our previous work. Three different kinds of near-infrared (NIR) absorbing pull-push acceptor-π-donor-π-acceptor (A-π-D-π-A) V-shaped chromophoric dyes have been synthesized. These dyes are architect by doing substitution with 5-hydroxy and 6-arylazonium on the benzo[a] naphtho[2,3-h] phenazine dione core. Phenazine and anthraquinone moieties were envisaged in a single molecule with a view to enhance the photophysical properties

This work is aimed at synthesizing novel molecules containing both phenazine and azo cores that were envisaged in a single molecule with a view to enhance the photophysical properties in the NIR region. In this study, we have extended our contribution to synthesis NIR absorbing dyes (**12–14**) as shown in

**250**

**Figure 4.**

*Structures of the near-IR absorbing dyes (***12–14***).*

acceptor.

**Figure 4**.

**5** as shown in **Figure 2** [32].

*o*-quinoid or dihydro structure.

in NIR region as shown in **Figure 3** [33].

In the present study, the use of 2-hydroxy-1,4-naphthoquinone (Lawsone) **5** coupling components and diazo components in the synthesis of azo disperse dyes followed by condensation with *o*–phenylenediamine OPDA to obtain the desired NIR absorbing azo dyes (**12–14**).

In this context, authors have extended our contribution to synthesis of three different kinds of near infrared (NIR) absorbing pull-push acceptor–π–donor–π acceptor (A–π–D–π–A) chromophoric dyes. The NIR absorbing dyes (**12–14**) were synthesized from derivatives of 2-hydroxy-3-(phenyldiazenyl)naphthalene-1,4-dione (**18–20)** and 2,3-diaminophenazine core (**21**) (**Figure 5**).

The scaffold of phenazine, *N,N*-dimethylaniline, and anthraquinone moieties was envisaged in a single molecule with a view to enhance the photophysical properties in NIR region. The UV-Vis absorption spectra of synthesized azo-azine dyes have been studied. The intermolecular interaction occurring in solvents of differing polarities as well in solution of different pH have been studied. The structures of the dyes are given in **Figure 4**. Synthetic route for the dyes **44–46** and their intermediates are depicted in **Figure 5**.

**Figure 5.** *Schematic representation of NIR azo dyes (***12–14***).*

#### **Figure 6.** *Visible absorption of the dyes (***18–20***) in DMF solvent.*


#### **Table 1.**

*Visible absorption of the dyes (***18–20** *and* **12–14***) in DMF solvent.*

**Figure 7.** *Visible absorption of the dyes (***12–14***) in DMF solvent.*

## **2.2 Optical properties**

The UV-visible absorption spectra of the dyes **(18–20 & 12–14)** were measured in *N,N-*dimethylformamide (DMF). These dyes do not show solvatochromism significantly. The dyes (**18–20**) showed absorption at 439–490 nm (**Figure 6** and **Table 1**).

**253**

**3.4 Characterization**

FT-IR (KBr, cm<sup>−</sup><sup>1</sup>

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes*

**3.1 General experimental procedure of the azo dyes (18–20)**

washed with water and then with aqueous EtOH, and was dried.

**3.2 General experimental procedure of the azo-phenazine dyes (12–14)**

**3.3 General experimental procedure of 2,3-diaminophenazine (21)**

at 100–110°C. The crude products were used without further purification.

*3.4.1 6-(Phenyldiazenyl)benzo[a]quinoxalino[2,3-i]phenazin-5-ol (***12***)*

Yield 72%; melting point (measured) >300°C.

The red-shifted absorptions owing to the π-conjugation framework are present in these dyes. The dyes (12–14) showed absorption at 620–710 nm due to the intramolecular charge transfer transition (ICT) between donor-acceptor pair (**Figure 7** and **Table 1**).

The aromatic primary amines (5 g) was partially dissolved in conc. HCl (5 mL)

Diketo-azo derivatives (**18–20**) and diaminophenazine (**21**) were mixed together then refluxed in acetic acid for 4 h. The AcOH was removed under reduced pressure in a rotary evaporator, and water was added to the residue. The precipitate was let out and filtered, washed with water and then with aqueous ethanol, and dried.

Finally powdered *o-*phenylenediamine (54.0 g, 0.5 mol) was dissolved in conc. hydrochloric acid (83.3 ml) and distilled water (2.5 L). A filtered solution of ferric chloride (400 g) in (750 ml) water was added slowly, and the mixture was stirred mechanically. After standing overnight at room temperature, the red-brown colored crystalline product was filtered off, washed with cold dilute 0.3 N HCl until free from ferric ions, then dissolved in hot water (2.5 L), and 2,3-diaminophenazine was precipitated by the addition of a concentrated solution of potassium hydroxide. The product was filtered off, washed with water, and dried at 100–110°C. The strongly alkaline filtrate was heated and acidified (pH 4.5) with glacial acetic acid. After cooling, 2-amino-3-hydroxy phenazine was collected, washed with water, and dried

) = 3057 (O–H), 1630 (C=N), 1589 (arom.), 1534 (arom. ring).

in 80 mL water and cooled to 0–5°C [34]. The solution of NaNO2 (2 g) in 5 mL water was added slowly to the reaction mixture, and the reaction temperature was kept below 5°C. The resulting aryl diazonium salt was added to the alkaline solution of Lawson (5 g) and NaOH (1.15 g) in 60 mL of water, and reaction temperature was maintained at 0–5°C. The reaction mass was stirred for 2.0–2.5 h, after which mixture was acidified with dil. HCl. The precipitate was settled down and filtered,

*DOI: http://dx.doi.org/10.5772/intechopen.81229*

**3. Experimental sections**

The red-shifted absorptions owing to the π-conjugation framework are present in these dyes. The dyes (12–14) showed absorption at 620–710 nm due to the intramolecular charge transfer transition (ICT) between donor-acceptor pair (**Figure 7** and **Table 1**).

## **3. Experimental sections**

*Chemistry and Technology of Natural and Synthetic Dyes and Pigments*

**Dye λmax (nm) (log Ɛ) Ɛmax (dm3**

*Visible absorption of the dyes (***18–20** *and* **12–14***) in DMF solvent.*

*Visible absorption of the dyes (***18–20***) in DMF solvent.*

 487 4.93 84,830 490 4.91 81,275 439 4.72 52,260 620 4.60 40,000 710 4.63 43,000 680 4.69 49,000

 **mol<sup>−</sup><sup>1</sup>**

 **cm<sup>−</sup><sup>1</sup> )**

**252**

**Figure 7.**

**Table 1.**

**Figure 6.**

**2.2 Optical properties**

*Visible absorption of the dyes (***12–14***) in DMF solvent.*

The UV-visible absorption spectra of the dyes **(18–20 & 12–14)** were measured in *N,N-*dimethylformamide (DMF). These dyes do not show solvatochromism significantly. The dyes (**18–20**) showed absorption at 439–490 nm (**Figure 6** and **Table 1**).

## **3.1 General experimental procedure of the azo dyes (18–20)**

The aromatic primary amines (5 g) was partially dissolved in conc. HCl (5 mL) in 80 mL water and cooled to 0–5°C [34]. The solution of NaNO2 (2 g) in 5 mL water was added slowly to the reaction mixture, and the reaction temperature was kept below 5°C. The resulting aryl diazonium salt was added to the alkaline solution of Lawson (5 g) and NaOH (1.15 g) in 60 mL of water, and reaction temperature was maintained at 0–5°C. The reaction mass was stirred for 2.0–2.5 h, after which mixture was acidified with dil. HCl. The precipitate was settled down and filtered, washed with water and then with aqueous EtOH, and was dried.

## **3.2 General experimental procedure of the azo-phenazine dyes (12–14)**

Diketo-azo derivatives (**18–20**) and diaminophenazine (**21**) were mixed together then refluxed in acetic acid for 4 h. The AcOH was removed under reduced pressure in a rotary evaporator, and water was added to the residue. The precipitate was let out and filtered, washed with water and then with aqueous ethanol, and dried.

## **3.3 General experimental procedure of 2,3-diaminophenazine (21)**

Finally powdered *o-*phenylenediamine (54.0 g, 0.5 mol) was dissolved in conc. hydrochloric acid (83.3 ml) and distilled water (2.5 L). A filtered solution of ferric chloride (400 g) in (750 ml) water was added slowly, and the mixture was stirred mechanically. After standing overnight at room temperature, the red-brown colored crystalline product was filtered off, washed with cold dilute 0.3 N HCl until free from ferric ions, then dissolved in hot water (2.5 L), and 2,3-diaminophenazine was precipitated by the addition of a concentrated solution of potassium hydroxide. The product was filtered off, washed with water, and dried at 100–110°C. The strongly alkaline filtrate was heated and acidified (pH 4.5) with glacial acetic acid. After cooling, 2-amino-3-hydroxy phenazine was collected, washed with water, and dried at 100–110°C. The crude products were used without further purification.

## **3.4 Characterization**

*3.4.1 6-(Phenyldiazenyl)benzo[a]quinoxalino[2,3-i]phenazin-5-ol (***12***)*

Yield 72%; melting point (measured) >300°C. FT-IR (KBr, cm<sup>−</sup><sup>1</sup> ) = 3057 (O–H), 1630 (C=N), 1589 (arom.), 1534 (arom. ring).

1 H-NMR (DMSO, 500 MHz) = δ 8.30–8.24 (m, 4H, aromatic), 8.26–8.16 (m, 3H, aromatic), 7.92–7.76 (m, 8H, aromatic), 5.2 (1H, s, OH).

*3.4.2 6-((4-(Dimethylamino)phenyl)diazenyl)benzo[a]quinoxalino[2,3-i] phenazin-5-ol (***45***)*

Yield 80%, melting point (measured) >300°C. FT-IR (KBr, cm<sup>−</sup><sup>1</sup> ) = 3169 (O–H), 1674 (C=N), 1633 (arom.), 1514 (arom. ring). <sup>1</sup> H-NMR (DMSO, 500 MHz) = δ 8.25 (s, 2H, aromatic), 8.23–7.78 (m, 12H, aromatic), 3.86 (s, 6H, CH3–N–CH3), 6.18 (1H, s, OH).

*3.4.3 2-((5-Hydroxybenzo [a]quinoxalino[2,3-i]phenazin-6 yl)diazenyl) anthracene-9,10-dione (***46***)*

Yield 67%, melting point (measured) >300°C. FT-IR (KBr, cm<sup>−</sup><sup>1</sup> ) = 3059 (O–H), 1629 (C=N), 1590 (arom.), 1529 (arom. ring). 1 H-NMR (DMSO, 500 MHz) = δ 8.304 (s, 2H, aromatic), 8.292 (m, 12H, aromatic), 7.77–7.76 (m, 3H, aromatic), 5.2 (1H, s, OH).

## **4. Conclusions**

Azo colorants represent the greatest production volume in dyestuff chemistry due to simplicity of coupling reaction, adaption to the needs of most diverse applications such as textile dying, coloring of plastics and polymer, in liquid crystal displays (LCD), optical data storage, nonlinear optics, biological and medical field, and advanced application in organic synthesis. In this context, authors have designed and developed push-pull chromophores of A-π-D-π-A type containing an electronwithdrawing azo core, phenazine moieties, and a hydroxyl group as electron donor. The benzo[a]quinoxalino[2,3-i]phenazin-5-ol moiety was introduced to make the system planer as well as to increase the п-conjugation. These synthesized chromophores were confirmed by FT-IR, 1 H-NMR, 13C-NMR, and MS spectral analysis. The optical properties of these dyes were studied in DMF. NIR absorbing dyes have been considered in numerous recent hi-tech applications like optical device, optical recordings, laser printings, laser thermal writing displays, infrared photography, and biological/medical applications. In optoelectronic application areas, especially,

**255**

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes*

NIR azo dyes may probably prove to be a solution to this problem.

NIR absorbing dyes are being developed and new structural designs of the dye chromophore molecules are being studied. Azo dyes are the most important class of organic dyes, but many of azo dyes suspect to be carcinogenic in nature. Therefore, the research of the dyes is aimed at development of new type of chromophores. The

There is an excellent range of organic compounds that absorb intensively higher than 700–1300 nm owing to electronic excitation. The basic acyclic NIR chromophores (polymethine dyes) as well as the basic cyclic NIR chromophores (annulenes, porphyrines, and tetraazaporphyrins) are well recognized. Structurally, more advanced NIR dyes with some meropolymethinic, quinonoid, and/or indigoid character will eventually be found. Color structure relationships are at present better well-known and more reliably predictable for closed shell than for open shell systems. On account of their special optical properties, there exists scope for further research into designing small molecules bearing donor and acceptor functional groups directly attached to the phenazine nucleus that could possess NIR optical spectra, which would be sensitive to presence of solution analytes such as cations/anions as well as to pollutants such as polycyclic aromatic hydrocarbons and nitroaromatics. Additionally, preparation of more examples of phenazine-based low-band gapcontaining molecules will also enhance its use in the field of organic photovoltaics.

Author is grateful to IntechOpen Publishers for being given the chance for contributory to the present book. This work was supported by Institute of Chemical

The authors declare no competing financial interest.

*DOI: http://dx.doi.org/10.5772/intechopen.81229*

**5. Future trends**

**Acknowledgements**

**Notes**

Technology, Mumbai, India.

NIR absorbing dyes are being developed and new structural designs of the dye chromophore molecules are being studied. Azo dyes are the most important class of organic dyes, but many of azo dyes suspect to be carcinogenic in nature. Therefore, the research of the dyes is aimed at development of new type of chromophores. The NIR azo dyes may probably prove to be a solution to this problem.

## **5. Future trends**

*Chemistry and Technology of Natural and Synthetic Dyes and Pigments*

aromatic), 7.92–7.76 (m, 8H, aromatic), 5.2 (1H, s, OH).

*3.4.2 6-((4-(Dimethylamino)phenyl)diazenyl)benzo[a]quinoxalino[2,3-i]*

Yield 80%, melting point (measured) >300°C. FT-IR (KBr, cm<sup>−</sup><sup>1</sup>

*3.4.3 2-((5-Hydroxybenzo [a]quinoxalino[2,3-i]phenazin-6 yl)diazenyl)*

Yield 67%, melting point (measured) >300°C. FT-IR (KBr, cm<sup>−</sup><sup>1</sup>

2H, aromatic), 8.292 (m, 12H, aromatic), 7.77–7.76 (m, 3H, aromatic), 5.2 (1H, s, OH).

Azo colorants represent the greatest production volume in dyestuff chemistry due to simplicity of coupling reaction, adaption to the needs of most diverse applications such as textile dying, coloring of plastics and polymer, in liquid crystal displays (LCD), optical data storage, nonlinear optics, biological and medical field, and advanced application in organic synthesis. In this context, authors have designed and developed push-pull chromophores of A-π-D-π-A type containing an electronwithdrawing azo core, phenazine moieties, and a hydroxyl group as electron donor. The benzo[a]quinoxalino[2,3-i]phenazin-5-ol moiety was introduced to make the system planer as well as to increase the п-conjugation. These synthesized chromo-

The optical properties of these dyes were studied in DMF. NIR absorbing dyes have been considered in numerous recent hi-tech applications like optical device, optical recordings, laser printings, laser thermal writing displays, infrared photography, and biological/medical applications. In optoelectronic application areas, especially,

(s, 2H, aromatic), 8.23–7.78 (m, 12H, aromatic), 3.86 (s, 6H, CH3–N–CH3), 6.18

1674 (C=N), 1633 (arom.), 1514 (arom. ring). <sup>1</sup>

*anthracene-9,10-dione (***46***)*

1629 (C=N), 1590 (arom.), 1529 (arom. ring). 1

phores were confirmed by FT-IR, 1

H-NMR (DMSO, 500 MHz) = δ 8.30–8.24 (m, 4H, aromatic), 8.26–8.16 (m, 3H,

) = 3169 (O–H),

) = 3059 (O–H),

H-NMR (DMSO, 500 MHz) = δ 8.304 (s,

H-NMR, 13C-NMR, and MS spectral analysis.

H-NMR (DMSO, 500 MHz) = δ 8.25

1

(1H, s, OH).

**4. Conclusions**

*phenazin-5-ol (***45***)*

**254**

There is an excellent range of organic compounds that absorb intensively higher than 700–1300 nm owing to electronic excitation. The basic acyclic NIR chromophores (polymethine dyes) as well as the basic cyclic NIR chromophores (annulenes, porphyrines, and tetraazaporphyrins) are well recognized. Structurally, more advanced NIR dyes with some meropolymethinic, quinonoid, and/or indigoid character will eventually be found. Color structure relationships are at present better well-known and more reliably predictable for closed shell than for open shell systems.

On account of their special optical properties, there exists scope for further research into designing small molecules bearing donor and acceptor functional groups directly attached to the phenazine nucleus that could possess NIR optical spectra, which would be sensitive to presence of solution analytes such as cations/anions as well as to pollutants such as polycyclic aromatic hydrocarbons and nitroaromatics. Additionally, preparation of more examples of phenazine-based low-band gapcontaining molecules will also enhance its use in the field of organic photovoltaics.

## **Acknowledgements**

Author is grateful to IntechOpen Publishers for being given the chance for contributory to the present book. This work was supported by Institute of Chemical Technology, Mumbai, India.

## **Notes**

The authors declare no competing financial interest.

## **Author details**

Sharad Rohidas Patil1,2\* and Amol S. Chaudhary3

1 Department of Chemistry, SPDM Arts, SBB and SHD Commerce and SMA Science College, Dhule, Maharashtra, India

2 Department of Chemistry, Uka Tarsadia University, Gopal-Vidyanagar, Maliba campus, Bardoli, Gujarat, India

3 R&D Division, Rextone Dyes Ltd, Vadodara, Gujarat, India

\*Address all correspondence to: sharad.omd.patil@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**257**

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes*

2001;**50**:117-126. DOI: 10.1016/ S0143-7208(01)00028-6

[9] Vijayaraghavan R, Vedaraman N, Surianarayanan M, MacFarlane DR. Extraction and recovery of azo dyes into an ionic liquid. Talanta. 2006;**69**:1059- 1062. DOI: 10.1016/j.talanta.2005.12.042

[10] Fleischmann C, Lievenbrück M, Ritter H. Polymers and dyes: Developments and applications. Polymer. 2015;**7**:717-746.

[11] Gouda MA, Eldien HF, Girges MM, Berghot MA. Synthesis and antitumor evaluation of thiophene based azo dyes incorporating pyrazolone moiety. Journal of Saudi Chemical Society. 2016;**20**:151-157. DOI: 10.1016/j.

[12] Nejati K, Rezvani Z, Seyedahmadian M, Seyedahmadian M. The synthesis, characterization, thermal and optical properties of copper, nickel, and vanadyl complexes derived from azo dyes. Dyes and Pigments. 2009;**83**:304- 311. DOI: 10.1016/j.dyepig.2009.05.007

[13] Dong M, Babalhavaeji A, Hansen MJ, Kalman L, Woolley GA. Red, farred, and near infrared photoswitches based on azonium ions. Chemical Communications. 2015;**51**:12981-12984.

[14] Salvador MA, Reis LV, Almeida P, Santos PF. Delocalized cationic azo dyes containing a thiazole moiety. Tetrahedron. 2008;**64**:299-303. DOI:

[15] Mikroyannidi J, Tsagkournos D, Sharma S, Kumar A, Vijay Y, Sharma G. Efficient bulk heterojunction solar cells based on low band gap bisazo dyes containing anthracene and/or pyrrole units. Solar Energy Materials and Solar Cells. 2010;**94**:2318-2327. DOI: 10.1016/j.

DOI: 10.1039/C5CC02804C

10.1016/j.tet.2007.11.004

solmat.2010.08.001

DOI: 10.3390/polym7040717

jscs.2012.06.004

*DOI: http://dx.doi.org/10.5772/intechopen.81229*

[1] Li Y, Patrick BO, Dolphin D. Nearinfrared absorbing azo dyes: Synthesis and X-ray crystallographic and spectral characterization of monoazopyrroles, bisazopyrroles, and a boron–azopyrrole complex. The Journal of Organic Chemistry. 2009;**74**:5237-5243. DOI:

[2] Singh RP, Singh PK, Singh RL. Role of azoreductases in bacterial decolorization of azo dyes. Current Trends in Biomedical Engineering & Biosciences. 2017;**9**:1-3. DOI: 10.19080/

[3] Telke A, Kalyani D, Jadhav J, Govindwar. Kinetics and mechanism of reactive red 141 degradation by a bacterial isolate *Rhizobium radiobacter* MTCC 8161. Acta Chimica Slovenica.

[4] Arslanoglu Y, Sevim AM, Hamuryudan E, Gul A. Near-IR absorbing phthalocyanines. Dyes and Pigments. 2006;**68**:129-132. DOI: 10.1016/j.dyepig.2005.01.019

[5] Saratale RG, Saratale GD, Chang JS, Govindwar SP. Bacterial decolorization and degradation of azo dyes: A review. Journal of the Taiwan Institute of Chemical Engineers. 2011;**42**:138-157. DOI: 10.1016/j.jtice.2010.06.006

[6] Gregory P. In: Hunger K, editor. Industrial Dyes: Chemistry, Properties and Applications. Weinheim: Wiley-

VCH; 2002. pp. 543-585

[7] Bamfield P, Hutchings MG. Chromic Phenomena: Technological Applications of Colour Chemistry. 2nd

[8] Koh J, Greaves AJ. Synthesis and application of an alkali-clearable azo disperse dye containing a fluorosulfonyl

hydrolysis kinetics. Dyes and Pigments.

group and analysis of its alkali-

ed. Cambridge: RSC; 2010

10.1021/jo9003019

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CTBEB.2017.09.555764

2008;**55**:320-329

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes DOI: http://dx.doi.org/10.5772/intechopen.81229*

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*Chemistry and Technology of Natural and Synthetic Dyes and Pigments*

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

1 Department of Chemistry, SPDM Arts, SBB and SHD Commerce and SMA

2 Department of Chemistry, Uka Tarsadia University, Gopal-Vidyanagar,

3 R&D Division, Rextone Dyes Ltd, Vadodara, Gujarat, India

\*Address all correspondence to: sharad.omd.patil@gmail.com

**256**

**Author details**

provided the original work is properly cited.

Sharad Rohidas Patil1,2\* and Amol S. Chaudhary3

Science College, Dhule, Maharashtra, India

Maliba campus, Bardoli, Gujarat, India

[1] Li Y, Patrick BO, Dolphin D. Nearinfrared absorbing azo dyes: Synthesis and X-ray crystallographic and spectral characterization of monoazopyrroles, bisazopyrroles, and a boron–azopyrrole complex. The Journal of Organic Chemistry. 2009;**74**:5237-5243. DOI: 10.1021/jo9003019

[2] Singh RP, Singh PK, Singh RL. Role of azoreductases in bacterial decolorization of azo dyes. Current Trends in Biomedical Engineering & Biosciences. 2017;**9**:1-3. DOI: 10.19080/ CTBEB.2017.09.555764

[3] Telke A, Kalyani D, Jadhav J, Govindwar. Kinetics and mechanism of reactive red 141 degradation by a bacterial isolate *Rhizobium radiobacter* MTCC 8161. Acta Chimica Slovenica. 2008;**55**:320-329

[4] Arslanoglu Y, Sevim AM, Hamuryudan E, Gul A. Near-IR absorbing phthalocyanines. Dyes and Pigments. 2006;**68**:129-132. DOI: 10.1016/j.dyepig.2005.01.019

[5] Saratale RG, Saratale GD, Chang JS, Govindwar SP. Bacterial decolorization and degradation of azo dyes: A review. Journal of the Taiwan Institute of Chemical Engineers. 2011;**42**:138-157. DOI: 10.1016/j.jtice.2010.06.006

[6] Gregory P. In: Hunger K, editor. Industrial Dyes: Chemistry, Properties and Applications. Weinheim: Wiley-VCH; 2002. pp. 543-585

[7] Bamfield P, Hutchings MG. Chromic Phenomena: Technological Applications of Colour Chemistry. 2nd ed. Cambridge: RSC; 2010

[8] Koh J, Greaves AJ. Synthesis and application of an alkali-clearable azo disperse dye containing a fluorosulfonyl group and analysis of its alkalihydrolysis kinetics. Dyes and Pigments.

2001;**50**:117-126. DOI: 10.1016/ S0143-7208(01)00028-6

[9] Vijayaraghavan R, Vedaraman N, Surianarayanan M, MacFarlane DR. Extraction and recovery of azo dyes into an ionic liquid. Talanta. 2006;**69**:1059- 1062. DOI: 10.1016/j.talanta.2005.12.042

[10] Fleischmann C, Lievenbrück M, Ritter H. Polymers and dyes: Developments and applications. Polymer. 2015;**7**:717-746. DOI: 10.3390/polym7040717

[11] Gouda MA, Eldien HF, Girges MM, Berghot MA. Synthesis and antitumor evaluation of thiophene based azo dyes incorporating pyrazolone moiety. Journal of Saudi Chemical Society. 2016;**20**:151-157. DOI: 10.1016/j. jscs.2012.06.004

[12] Nejati K, Rezvani Z, Seyedahmadian M, Seyedahmadian M. The synthesis, characterization, thermal and optical properties of copper, nickel, and vanadyl complexes derived from azo dyes. Dyes and Pigments. 2009;**83**:304- 311. DOI: 10.1016/j.dyepig.2009.05.007

[13] Dong M, Babalhavaeji A, Hansen MJ, Kalman L, Woolley GA. Red, farred, and near infrared photoswitches based on azonium ions. Chemical Communications. 2015;**51**:12981-12984. DOI: 10.1039/C5CC02804C

[14] Salvador MA, Reis LV, Almeida P, Santos PF. Delocalized cationic azo dyes containing a thiazole moiety. Tetrahedron. 2008;**64**:299-303. DOI: 10.1016/j.tet.2007.11.004

[15] Mikroyannidi J, Tsagkournos D, Sharma S, Kumar A, Vijay Y, Sharma G. Efficient bulk heterojunction solar cells based on low band gap bisazo dyes containing anthracene and/or pyrrole units. Solar Energy Materials and Solar Cells. 2010;**94**:2318-2327. DOI: 10.1016/j. solmat.2010.08.001

[16] Fuxin H, Yiqun W, Donghong G, Fuxi G. Synthesis, spectroscopic and thermal properties of nickel (II) eazo complexes with blue-violet light wavelength. Dyes and Pigments. 2005;**66**:77-82. DOI: 10.1016/j. dyepig.2004.08.013

[17] Knischka R, Lehmann U, Stadler U, Mamak M, Benkhoff J. Novel approaches in NIR curing technology. Progress in Organic Coating. 2009;**64**:171-174. DOI: 10.1016/j. porgcoat.2008.09.015

[18] Sekar N, Raut R, Umape P. Near infrared absorbing iron-complexed colorants for photovoltaic applications. Materials Science and Engineering B. 2010;**168**:259-262. DOI: 10.1016/j. mseb.2010.01.018

[19] Lamnatou C, Chemisana D. Solar radiation manipulations and their role in greenhouse claddings: Fresnel lenses, NIR- and UV-blocking materials. Renewable and Sustainable Energy Reviews. 2013;**18**:271-287. DOI: 10.1016/j.rser.2012.09.041

[20] Li N, J L, Li H, Kang E. Nonlinear optical properties and memory effects of the azo polymers carrying different substituents. Dyes and Pigments. 2011;**88**:18-24. DOI: 10.1016/j. dyepig.2010.04.010

[21] Salvador M, Almeida P, Reis L, Santos P. Near-infrared absorbing delocalized cationic azo dyes. Dyes and Pigments. 2009;**82**:118-123. DOI: 10.1016/j.dyepig.2008.12.003

[22] Kaur P, Sareen D. The synthesis and development of a dual-analyte colorimetric sensor: Simultaneous estimation of Hg2+ and Fe3+. Dyes and Pigments. 2011;**88**:296-300. DOI: 10.1016/j.dyepig.2010.07.012

[23] So B, Kim H, Lee S, Song H, Park J. Novel bent-shaped liquid crystalline compounds: IV. Dimesogenic compounds containing 2-hydroxy-1,3-dioxypropylene and azobenzene mesogens. Dyes and Pigments. 2006;**70**:38-42. DOI: 10.1016/j.dyepig.2005.04.006

[24] Tsai P, Wang I. A facile synthesis of some new pyrazolo[1,5-a]pyrimidine heterocyclic disazo dyes and an evaluation of their solvatochromic behavior. Dyes and Pigments. 2007;**74**:578-584. DOI: 10.1016/j. dyepig.2006.03.022

[25] Karcı F, Karcı F. The synthesis and solvatochromic properties of some novel heterocyclic disazo dyes derived from barbituric acid. Dyes and Pigments. 2008;**77**:451-456. DOI: 10.1016/j. dyepig.2007.07.009

[26] Yazdanbakhsh R, Mohammadi A, Abbasnia M. Some heterocyclic azo dyes derived from thiazolyl derivatives; synthesis; substituent effects and solvatochromic studies. Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy. 2010;**77**:1084-1087. DOI: 10.1016/j. saa.2010.08.079

[27] Ucar M, Polat K, Solak A, Toyc M, Aksu M. The electrochemical behaviour of 20-halogenated derivatives of 4-methoxyazobenzene at a mercury electrode. Dyes and Pigments. 2010;**87**:55-61. DOI: 10.1016/j. dyepig.2010.02.004

[28] Wang D, He Y, Deng W, Wang X. The photoinduced surface-relief-grating formation behavior of side-chain azo polymers with narrow Mr distribution. Dyes and Pigments. 2009;**82**:286-292. DOI: 10.1016/j.dyepig.2009.01.012

[29] Zollinger H. Color chemistry. In: Syntheses, Properties, and Applications of Organic Dyes and Pigments. 3rd ed. Zurich: Verlag Helvetica Chimia Acta, Wiley VCH; 2003

[30] Banerjee S. Phenazines as chemosensors of solution analytes and as sensitizers in organic photovoltaics.

**259**

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes*

*DOI: http://dx.doi.org/10.5772/intechopen.81229*

ARKIVOC. 2016;**i**:82-110. DOI: 10.3998/

[31] Richards G, Hill JP, Subbaiyan N, D'Souza F, Paul A, Mark K, et al.

[32] Romanyuk AL, Polishchuk OP, Litvin BL, Ganushchak N, Russ I. Synthesis and transformations of 2-hydroxy-3-arylazo-1,4-

naphthoquinones. Journal of General Chemistry. 2002;**72**:251-254. DOI:

[33] Choudhary A, Patil S, Sekar N. Solvatochromism, halochromism, and azo-hydrazone tautomerism in novel V-shaped azo-azine colorants— Consolidated experimental and computational approach. Coloration Technology. 2016;**132**:1-12. DOI:

[34] Mei L, Tai LS, Tao FH, Jie S, Rong QL. A novel synthesis of 2,3-diaminophenazine. Research on Chemical Intermediates. 2012;**38**:499- 505. DOI: 10.1007/s11164-011-0366-z

10.1023/A:1015429803432

10.1111/cote.12226

Pyrazinacenes: Aza analogues of acenes. The Journal of Organic Chemistry. 2009;**74**:8914-8923. DOI: 10.1021/

ark.5550190.p009.347

jo901832n

*Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes DOI: http://dx.doi.org/10.5772/intechopen.81229*

ARKIVOC. 2016;**i**:82-110. DOI: 10.3998/ ark.5550190.p009.347

*Chemistry and Technology of Natural and Synthetic Dyes and Pigments*

2-hydroxy-1,3-dioxypropylene and azobenzene mesogens. Dyes and Pigments. 2006;**70**:38-42. DOI: 10.1016/j.dyepig.2005.04.006

[24] Tsai P, Wang I. A facile synthesis of some new pyrazolo[1,5-a]pyrimidine heterocyclic disazo dyes and an evaluation of their solvatochromic behavior. Dyes and Pigments. 2007;**74**:578-584. DOI: 10.1016/j.

[25] Karcı F, Karcı F. The synthesis and solvatochromic properties of some novel heterocyclic disazo dyes derived from barbituric acid. Dyes and Pigments. 2008;**77**:451-456. DOI: 10.1016/j.

[26] Yazdanbakhsh R, Mohammadi A, Abbasnia M. Some heterocyclic azo dyes derived from thiazolyl derivatives; synthesis; substituent effects and solvatochromic studies. Spectrochimica Acta. Part A, Molecular

and Biomolecular Spectroscopy. 2010;**77**:1084-1087. DOI: 10.1016/j.

of 20-halogenated derivatives of 4-methoxyazobenzene at a mercury electrode. Dyes and Pigments. 2010;**87**:55-61. DOI: 10.1016/j.

[27] Ucar M, Polat K, Solak A, Toyc M, Aksu M. The electrochemical behaviour

[28] Wang D, He Y, Deng W, Wang X. The photoinduced surface-relief-grating formation behavior of side-chain azo polymers with narrow Mr distribution. Dyes and Pigments. 2009;**82**:286-292. DOI: 10.1016/j.dyepig.2009.01.012

[29] Zollinger H. Color chemistry. In: Syntheses, Properties, and Applications of Organic Dyes and Pigments. 3rd ed. Zurich: Verlag Helvetica Chimia Acta,

chemosensors of solution analytes and as sensitizers in organic photovoltaics.

[30] Banerjee S. Phenazines as

dyepig.2006.03.022

dyepig.2007.07.009

saa.2010.08.079

dyepig.2010.02.004

Wiley VCH; 2003

[16] Fuxin H, Yiqun W, Donghong G, Fuxi G. Synthesis, spectroscopic and thermal properties of nickel (II) eazo complexes with blue-violet light wavelength. Dyes and Pigments. 2005;**66**:77-82. DOI: 10.1016/j.

[17] Knischka R, Lehmann U, Stadler U, Mamak M, Benkhoff J. Novel approaches in NIR curing technology.

[18] Sekar N, Raut R, Umape P. Near infrared absorbing iron-complexed colorants for photovoltaic applications. Materials Science and Engineering B. 2010;**168**:259-262. DOI: 10.1016/j.

[19] Lamnatou C, Chemisana D. Solar radiation manipulations and their role in greenhouse claddings: Fresnel lenses, NIR- and UV-blocking materials. Renewable and Sustainable Energy Reviews. 2013;**18**:271-287. DOI:

10.1016/j.rser.2012.09.041

dyepig.2010.04.010

[20] Li N, J L, Li H, Kang E. Nonlinear optical properties and memory effects of the azo polymers carrying different substituents. Dyes and Pigments. 2011;**88**:18-24. DOI: 10.1016/j.

[21] Salvador M, Almeida P, Reis L, Santos P. Near-infrared absorbing delocalized cationic azo dyes. Dyes and Pigments. 2009;**82**:118-123. DOI:

[22] Kaur P, Sareen D. The synthesis and development of a dual-analyte colorimetric sensor: Simultaneous estimation of Hg2+ and Fe3+. Dyes and Pigments. 2011;**88**:296-300. DOI:

10.1016/j.dyepig.2008.12.003

10.1016/j.dyepig.2010.07.012

[23] So B, Kim H, Lee S, Song H, Park J. Novel bent-shaped liquid crystalline compounds: IV.

Dimesogenic compounds containing

Progress in Organic Coating. 2009;**64**:171-174. DOI: 10.1016/j.

porgcoat.2008.09.015

mseb.2010.01.018

dyepig.2004.08.013

**258**

[31] Richards G, Hill JP, Subbaiyan N, D'Souza F, Paul A, Mark K, et al. Pyrazinacenes: Aza analogues of acenes. The Journal of Organic Chemistry. 2009;**74**:8914-8923. DOI: 10.1021/ jo901832n

[32] Romanyuk AL, Polishchuk OP, Litvin BL, Ganushchak N, Russ I. Synthesis and transformations of 2-hydroxy-3-arylazo-1,4 naphthoquinones. Journal of General Chemistry. 2002;**72**:251-254. DOI: 10.1023/A:1015429803432

[33] Choudhary A, Patil S, Sekar N. Solvatochromism, halochromism, and azo-hydrazone tautomerism in novel V-shaped azo-azine colorants— Consolidated experimental and computational approach. Coloration Technology. 2016;**132**:1-12. DOI: 10.1111/cote.12226

[34] Mei L, Tai LS, Tao FH, Jie S, Rong QL. A novel synthesis of 2,3-diaminophenazine. Research on Chemical Intermediates. 2012;**38**:499- 505. DOI: 10.1007/s11164-011-0366-z

**Chapter 12**

Resins

**Abstract**

and R3.

**261**

environmental purification

**1. Introduction**

Removal of Methylene Blue Dyes

Removal of cationic dyes from industrial effluents is still a big and challenging subject in the field of environmental purification. Millions of tons of cationic dyes are consumed by the textile, rubber, paper, and plastic industries. These dyes have thousands of different chemical structures. Most of them have special properties, such as high hydrophilicity and stability to light or heat. Adsorption is commonly used as a technique for removing dyes. Removal of cationic dyes by adsorption is a promising approach because of its low performance cost and easy technical access. The amount adsorbed of the dye onto the polymeric resin is studied with time for estimating the adsorption mechanism. The adsorption of dye with time shows that mixing period of 10 min is optimum for attaining equilibrium with respect to R1 and R2, while attaining equilibrium with R3 takes 60 min. This findings represent a

rapid kinetic for adsorption of MB, particularly R1, on the prepared resins. Different kinetic models were applied on the obtained results and the kinetic parameters were determined. The kinetic models correlate the amount adsorbed of dye with time. The values of calculated adsorption capacity qe and the linear regression coefficient clarify that the studied kinetic model could not fit with the experimental results for adsorption of MB onto R1, R2, and R3. The results of the studied kinetic model clarify that the experimental results for adsorption of MB onto R1, R2, and R3 could be described by kinetic model supporting chemical adsorption. The sorption of MB could be favorably described by the pseudo-secondorder kinetic model onto the composite resins. This finding refers to the participation of chemical adsorption within the adsorption mechanism for MB onto R1, R2,

**Keywords:** blue dyes, composite polymeric-apatite resins, cationic dyes,

The environmental issues associated with residual dye content or residual color

in treated textile effluents are always a concern for each textile operator that

from Aqueous System Using

*Nasser S. Awwad, Adel A. El-Zahhar*

*and Jamila A.M. Alasmary*

Composite Polymeric-Apatite

## **Chapter 12**
