Design and Synthesis of Novel Antimicrobial Acyclic and Heterocyclic Dyes and Their Precursors for Dyeing and/or Textile Finishing Based on 2-N-Acylamino-4,5,6,7-tetrahydro-benzo[b]thiophene Systems

A series of novel polyfunctionalized acyclic and heterocyclic dye precursors and their respective azo (hydrazone) counterpart dyes and dye precursors based on conjugate enaminones and/or enaminonitrile moieties were synthesized. The dyes and their precursors are based on 2-cyano-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-acetamide, 2-ethoxycarbonyl-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-acetamide or 2-phenylcarbamoyl-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-acetamide systems as precursors. The latter compounds were used to synthesize polyfunctional thiophene-, thiazole-, pyrazole, pyridine-, pyrimidine-, oxazine-, as well as acyclic moieties. The dyes and dye precursors were characterized by elemental analysis and spectral methods. All dyes and their precursors were screened in vitro and evaluated for both their antibacterial and antifungal activities. MIC data of the novel dye systems and their respective precursors showed significant antimicrobial activity against most tested organisms. Some compounds exhibited comparable or even higher efficiency than selected standards. Dyes were applied at 5% depth for disperse dyeing of nylon, acetate and polyester fabrics. Their spectral characteristics and fastness properties were measured and evaluated.

Many researchers have explored in the field of simultaneous dyeing and functional finishing of textiles, such as the simultaneous dyeing and durable press finishing of cotton [25][26][27], the combination of dyeing and durable press finishing of silk [28,29], the simultaneous dyeing and finishing of wool [30], as well as the simultaneous dyeing and antimicrobial finishing of acrylic fabrics [31]. Other reports concerning antimicrobial functional finishing of synthetic fabrics via treatment with either N-haloamine moieties or by quaternary ammonium salts (QAS) has been discussed [32,33]. Both treatments may limit or affect the dyeing of the finished fabric. Chlorine bleach is needed in N-haloamine treatments, while the use of QAS may occupy some available dye sites within the fabrics, thus interfering with the dyeing behavior of the resultant fabric.
At the other extreme enaminone systems have been reported as important building blocks in heterocyclic synthesis [34,35]. Azo dyes based on the conjugate enaminones or enaminonitriles containing the respective conjugate systems O=C-(C=C) n -N-and N≡C-(C=C) n -N-have attracted ongoing attention. Besides having important dyeing capabilities, they provide the basis for the expanding field of structural studies [36][37][38]. Their importance as azo dyes and azo pigments depends on their donating-attracting effects which leads to their existence in several tautomeric forms connected with different types of hydrogen bonds. The existence of azo-hydrazone tautomerism affects the basic characteristics (colour tone, photostability) of azo dyes which can be used for the design of compounds having required colour properties.
Based upon the above considerations and in a continuation of our program directed toward the synthesis of bioactive heterocyclic systems [39][40][41][42], we therefore consider it worthwhile to design and synthesize heterocyclic functional azo dyes that combine the favorable properties of conjugate enaminone, enaminonitrile and azo systems with the hope that both dyeing and antimicrobial capabilities for textile finish may be achieved.
The synthetic strategy of the investigated dyes and their precursors depended on the competition of the reaction pathways which followed nucleophilic displacement, β-attack, Gewald type reaction, dinucleophilic bielectrophilic attack, dipolar cyclization and condensation reactions. This led to the diversity of the reaction products.
The novel compounds could be leads for the development of new functional materials with special finish properties for textile fabrics. Moreover, the results of the present study may point that the novel products could be useful as synthetic precursors for azo-and azomethine ligands or polymethine dyes which may be suitable for both electronic and optical applications.

A B
Aiming to produce novel azo dyes and dye precursors with biological activities for dyeing and/or finishing of textile fibers, we considered the regioselectivity for attack on the key precursors 2, 3 and 4 by different reagents. Thus, subjecting the title precursors to electrophilic or nucleophilic attack on their respective cyano-, ethoxycarbonyl-, and phenylcarbamoyl acetamido moieties, a variety of highly functionalized acyclic or heterocyclic molecules were obtained. When the intermediates 2, 3 and 4 were subjected to coupling with diazotized aryl (heteraryl) amines, the corresponding cyano-, ethoxycarbonyl-, or phenylcarbamoyl azo (hydrazone) dyes 8a-d, 9a-e and 10 were produced (Scheme 3). The dyes may exist in two possible tautomeric forms, namely, the azo-enol form (A) and the hydrazo-keto form (B). The dyes revealed common features indicating their existence in the azo-hydrazone form, whereby they exhibited intense amidic C=O absorptions around 1640 cm −1 (IR), δ-1 H singlets about 12.80 ppm corresponding to a tautomeric hydrazone NH, along with singlets at δ ~ 10.88-15.70 ppm assigned to an enolic OH ( 1 H-NMR). Other ν max values due to CN, ethoxycarbonyl C=O, phenyl-carbamoyl C=O (IR) in addition to δ-1 H signals exhibited for four cyclohexene CH 2 s, amidic NH, ester CH 3 and CH 2 as well as phenyl aromatic protons ( 1 H-NMR) were detected in the respective spectral regions. The mass spectra of the dyes revealed molecular ion peaks [M + ] in agreement with their molecular formulae.
Treatment of the key precursors 2, 3 and 4 with active methylene reagents (XCH 2 Y; X=Y=CN; X=CN, Y=CO 2 Et; X=Y=COCH 3 ; X=COCH 3 , Y=CO 2 Et) afforded the respective 2-oxopyridine derivatives 11a-d, 12a-b, 13a-b (Scheme 4). The reaction took place via 1,3-dinucleophilic attack by the active methylene reagent on the acetamido 1,3-bielectrophilic moiety of the starting materials. The synthesis of compounds 11a-d and their analytical data were previously described by our group [42].  All data for compounds 12a-b, 13a-b were consistent with the proposed cyclization mechanism. The absence of the cited δ-1 H CH 2 singlets for the acetamido methylene protons observed with the respective precursors 3, 4 at δ~ 3.84 ppm and the appearance of the pyridine C5-H protons at δ 7.92, 6.90, 6.92, 6.90 ppm in their respective 1 H-NMR spectra confirmed the proposed structures. Moreover, δ-1 H signals for OH were integrated at δ 11.76, 11.75 ppm ( 1 H-NMR) for compounds 12b, 13b. Compounds 12a, 12b revealed δ-1 H triplets about δ 1.13 ppm and δ-1 H quartets about δ 3.56 ppm due to the ester CH 3 and CH 2 protons, respectively.
Studying the absorption spectra of the resulting dyes, it is worthy of mention that, upon introduction of an aryl diazenyl group into the enaminone dye precursors 11a-d, 12a-b, the structural potential increases even more as the azo coupling products were found to exist in various tautomeric forms. The resulting dyes may exist as azo-keto; azo-enamino, hydrazone-keto, hydrazone imino, and azo-enol form species. Thus, the IR spectra of the dyes 14a-d, 15a-b, 16a-b exhibited a common ring carbonyl absorption shifted to a low frequency domain around 1675 cm −1 due to conjugation of the C=O with the -C=C-in the enaminone system and/or the possibility of hydrogen bond formation (compounds 16a-b, Scheme 11). Additionally, the azo-hydrazone tautomer is evident in the 1 H-NMR spectra of the dyes, where the H peak of the hydrazone imine characteristically appearing at 12.35 ppm. The mass spectra of the dyes revealed [M + ] ion peaks which corresponded to their expected molecular formulae.
Other 2-oxopyridine systems 17a-b, were produced via treatment of the start precursor 3 with benzylidene carbonitrile reagents [51] (PhCH=C(CN)X; X=CN; X=CO 2 Et) (Scheme 6).  The reaction took place through β-attack followed by 1,6-dipolar intramolecular cyclization with concomitant aromatization.  At the other extreme, the reaction of the start precursor 4 with phenyl isothiocyanate in basic dimethylformamide followed by heterocyclization using α-halo carbonyl reagents (XCH 2 -C(=O)R; X=Cl, R=CO 2 Et; X=Br, R=Ph; X=Cl, R=CH 3 ) afforded the polyfunctional thiophene or thiazole derivatives 18a-b, 19, respectively (Scheme 7). The reaction product depended on the nature of the α-halocarbonyl reagent [44]. The mechanism of reaction involved the intermediate formation of the potassium sulphide salt A. The disappearance of δ-1 H acetamido CH 2 singlet observed with the precursor 4 as revealed from the 1 H-NMR spectra of 18a-b, 19 and the appearance of ester CH 3 triplets at δ 1.16 ppm and a CH 2 quartet at δ 4.08 ppm for compound 18a, along with the existence of a δ-1 H singlet at 6.62 ppm assigned to the thiazole C5-H proton in compound 19 were sufficient proof for the proposed structures. Moreover the mass spectra of 18a-b displayed molecular ion peaks [ At the other extreme, polyfunctional thiophene derivative 20 was designed via a reaction of the key precursor 3 with elemental sulfur and malononitrile (Gewald Pathway). The reaction took place through the intermediate formation of A and B. The latter suffered intramolecular 1,5-dipolar cyclization to afford the desired thiophene derivative 20 (Scheme 7). The 1 H-NMR spectrum of 20 revealed the existence of a D 2 O exchangeable NH 2 singlet at δ 3.82 ppm, as well as the appearance of δ-1 H singlet at 11.79 ppm assigned to an OH proton. Moreover, in the mass spectrum of 20 the [M + ] ion at m/z 344 confirmed the molecular formula C 15 H 12 N 4 O 2 S 2 .
On the other hand, when 3 was reacted with either hydrazine hydrate or phenyl hydrazine, the corresponding 3-oxopyrazole systems 21a-b were produced (Scheme 8). The reaction involved 1,2-dinucleophilic cyclization by the hydrazine reagents on malonamic ester bielectrophilic moiety in 3. Similarly when 9a was subjected to the same reaction, the corresponding 5-oxopyrazole azo dyes 22a-b were formed according to the same aforementioned mechanism (Scheme 8). Microanalysis and spectral data of the pyrazole systems 21a-b, 22a-b were fully consistent with the proposed structures. The existence of a common carbonyl absorption around 1672 cm −1 corresponding to the 3-oxopyrazole function (IR), the disappearance of the δ-1 H ester CH 3 and CH 2 signals detected with the starting acyclic precursor 9a ( 1 H-NMR of 22a) and the appearance of the-2-pyrazole phenyl multiplet (along with the phenyl hydrazone multiplet) at δ 6.22-7.65 ppm ( 1 H NMR of 22b) were considered as a definite proof for the proposed pyrazole systems. The mass spectra of the synthesized pyrazole systems displayed molecular ion peaks [ In continuation of our aim for tailoring new functional heterocyclic targets with biological activity, we focused our study to a cyclization reaction of the acyclic hydrazone dye 10 with methylene carbonitrile reagents (XCH 2 CN; X=CN; X=CO 2 Et) in the presence of a catalytic amount of triethylamine. The reaction afforded the functionalized 1,3-oxazine azo dyes 23a-b, respectively (Scheme 9). Scheme 9. Synthesis of functionalized oxazinylidene azo dyes 23a-b. The proposed mechanism involves nucleophilic attack by the enolic tautomer of 10 (azo-enol form) followed by 1,6-dipolar cyclization. The reaction took place through the non-isolable intermediate A.
The data obtained from the IR, 1 H-NMR, and MS spectra for the oxazine systems 23a-b confirmed the proposed cyclization mechanism. Both dye systems displayed, in their respective 1 H-NMR spectra oxazine C5-H protons, both at δ 6.92 ppm, as well as two D 2 O exchangeable NH 2 singlets, both at δ 3.64. Compound 23a exhibited a δ-1 H singlet at 8.27 ppm due to the oxazine C4-imino function, while 23b showed ν max at 1662 cm −1 due to the oxazine C4-oxo absorption. The mass spectra of 23a-b exhibited [M + ] ion peaks at m/z 509 and [M + +1] at 511, respectively, indicating their corresponding molecular formulae C 27 H 23 N 7 O 2 S and C 27 H 22 N 6 O 3 S.
Next, we moved to study the reaction of the acyclic hydrazone dyes 9a and 10 with phenyl isothiocyanate in 1,4-dioxane containing a catalytic amount of triethylamine. The reaction involved a nucleophilic attack by the amidic NH function in 9a and 10 on the C=S terminal of the isocyanate reagent to produce the acyclic intermediate A. the latter then underwent 1,6-dipolar cyclization through elimination of EtOH or H-OH to afford the functionalized pyrimidine azo (hydrazone) dye systems 24a and 24b, respectively (Scheme 10).
The analytical and spectral data of the dyes 24a-b were in agreement with the proposed structures. Dye 24a revealed two C=O absorptions at 1665, 1620 cm −1 corresponding to the 4,6-pyrimidinedioxo functions, while 24b exhibited a 6-oxopyrimidine carbonyl absorption at 1664 cm −1 . Both dyes showed, in their 1 H-NMR spectra a singlet at δ~ 11.80 ppm due to the tautomeric hydrazone NH. The present discussion will describe the effect of the structural configuration of these dyes on the shifts of ultraviolet-visible absorption maxima and the intensity of colour and fastness properties. Data of UV/vis absorption maxima, fastness and optical properties, as well as the colour shades on tested fabrics (nylon 66, acetate and polyester) are listed in Table 1.

Spectral Characterization
The target dyes revealed analytical and spectral data in accordance to their molecular structures. Most dyes exist in the azo-hydrazone tautomeric structure, as revealed by spectral data. The possibility of H bond formation between the imine-H of the hydrazone tautomer and the carbonyl bond (Scheme 11) as well as presence of a C=O moiety in an enaminone conjugate system would shift the carbonyl absorption band to a low frequency domain (ν max 1610-1600 cm −1 ). Additionally, the azo-hydrazone tautomer is evident in the 1 H-NMR spectra where the H peak of the imine group characteristically appears at δ ~12.00 ppm. The UV/vis absorption maxima of the synthesized dyes were tested in the aqueous solution [after adding dimethyl sulphoxide (1.00/20.00 mL) to improve the water solubility]. From the analysis of the UV/vis absorption data, it was found that, for each inter-related system, none of the dyes changed significantly with respect to each other.
The bathochromic shift observed for λ max values of some dyes could be attributed to more extensive delocalization within each system configuration which in turn, is dependent on the presence of electron donating substituents. Suitable electronic absorptions were found in the blue violet region of 390-420 nm. An absorption band below 250 nm was detected for most dye systems which could be relatable to electron transition through a possible azo ligand resulting from intramolecular chelation by H-bond (Scheme 11). A common absorption band appearing around 740 nm was observed in the UV/vis spectra of nearly all synthesized dyes which could arise from a transition involving electron migration along the entire conjugate enaminone and/or enaminonitrile configuration. The UV/vis absorption data showed no significant bathochromic or hypsochromic shifts when measured in ethanol as a solvent.

Colour Assessment and Dyeing Properties
The novel dyes were applied to nylon 66, acetate and polyester fabrics at 5% depth by the high-temperature-pressure technique and gave generally bright, intense golden yellow, mustard yellow, orange, dark orange, brick red, brick brown, pale green and bright green hues. Due to the good migration properties of these disperse dyes, leveling agents were not required. The dyed fabrics were analyzed on qualitative tests by estimation fastness shades with grey scale, the results were expressed in terms of colour ratings 1-5 (Table 1).
In general, the data revealed that wash fastness rating for change in colour as well as staining of adjacent fabrics are very good (4)(5). Rubbing fastness of the samples, assessed in terms of dry and wet rubbing indicated good fastness to rubbing for both dry and wet (3)(4)(5). Perspiration fastness properties (acidic and alkaline) of the dyed samples in terms of ratings for staining of adjacent fabrics and change are very good (4)(5). The high ratings for change in colour at both acidic and alkaline conditions indicate that the sensitivity of the dyed samples are not related to PH. This may be due to the stability of the dyes towards degradation under either acidic or basic conditions. Light fastness of the dyeing was of a generally of good order (3)(4)(5). The lightness ratings were primarily influenced by the depth of the hue. The data for colour yield expressed as K/S indicated higher values on nylon in comparison to other fabrics. This is probably due to the high substantivity of the dyes on nylon.
From the aforementioned data, it is noteworthy that the fastness properties for the dyes under investigation are inter-related since they depend, among other factors, on the rate of diffusion of the dye in the fabric. This rate is a function of the geometry of the dye molecule. Fastness to rubbing depends on the presence of loose dye particles on the fabric surface. The washing and perspiration fastness is, to a certain extent, dependent on the substantivity of the dye for the fabric which determines its tendency to partition in favour of the fabric.

Antimicrobial Evaluation of the Newly Synthesized Compounds
The newly synthesized dyes and dye precursor were screened in vitro for their antibacterial and antifungal activities against selected microbial strains, namely Escherichia coli ECT 101 (Gram-negative bacteria), Bacillus subtilis CECT 498 and Bacillus cereus CECT 148 (Gram-positive bacteria) and Candida albicans 1394 (a representative fungal species).
The minimal inhibitory concentration (MIC) in μg/mL was determined using an adapted agar streak dilution method based on radial diffusion [45,46]. Under the same conditions, solutions of control antibiotics ampicillin (antibacterial) and cycloheximide (antifungal) were used as standards.
The antimicrobial screening results of the synthesized compounds and standard antibiotics are given in Table 2. Structure-antimicrobial (biological) activity relationship for the newly synthesized compounds were studied and determined against the selected test bacterial and fungal strains.  According to this study it was observed that the MIC values of the dyes and dye precursors are generally within the 0.04-30.00 μg/mL range against all tested microbial organisms, which reveals significant and potent antimicrobial activity (Table 2). However, a number of the synthesized compounds (dyes 8a-d, 9a-e, 15b, 16a-b, 22b, 23a and dye precursors 3, 13b, 17a, 21a) were found to be totally inactive towards the Gram-negative bacterial species E. coli. This could be related to the presence of electron withdrawing functions (CN, CO 2 Et, CONHPh, N=N-) conjugated with electron donating groups (NH 2 , OH, =N-NH). The increase in electron attracting character of these compounds cause a relative decrease in their biological activity. Furthermore, the intricate nature of the cell wall of this Gram-negative bacterial strain compared with Gram-positive test bacteria B. subtilis and B.cereus may inhibit the adsorption of most compounds onto the surface and consequently revealed weaker susceptibility for these compounds.
On the other hand, as an impressive result, the active concentration of almost all synthesized dyes and dye precursors against tested Gram-positive bacteria was found to be similar or even lower values compared with control antibiotics against these strains ( Table 2). This may be attributed to the presence of an oxo function in the main structure of the dyes and dye precursors which could be responsible to bind or complex with nucleophilic amino acids in proteins leading to inactivation of the microorganisms and loss of function. Additionally, the presence of an oxo function in the synthesized compounds may lead to the formation of H-bonds with water molecules which enable these compounds to more readily form positive ions in aqueous solution thereby inhibiting microbial growth by adsorption onto the bacterial surface [47]. Also, it is worth of mentioning that a high level of antifungal activities was observed for all tested compounds against the selected yeast C. albicans ( Table 2). The dyes 8a, 8c, 9a, 9a-d, 10, 14a-b, 14d, 15a, 16a-b, 22b, 23a-b, 24b and dye precursors  3, 4, 5, 6, 7, 12a-b, 13a-b, 17a-b, 18a-b, 20, 21a-b all exhibited superior antifungal activity than cycloheximide against this fungal strain.

Equipment
All melting points were determined on an Electrothermal digital melting point apparatus and are uncorrected. IR spectra (KBr discs) were recorded on a FTIR plus 460 or Pye Unicam SP-1000 spectrophotometer. 1 H-NMR spectra were recorded with Varian Gemini-200 (200 MHz) and Jeol AS 500 MHz instruments, 13 C-NMR spectra were measured with the Jeol AS 500 MHz instrument. Both spectra were performed in DMSO-d 6 as solvent using TMS as internal standard and chemical shifts are expressed as δ ppm. MS (EI) spectra were recorded with Hewlett Packard 5988 A GC/MS system and GCMS-QP 1000 Ex Shimadzu instruments. UV/vis absorption maxima (λ max ) were recorded on UV-16600 Series. Analytical data were obtained from the Micro-analytical Data Unit at Cairo University and were performed on Vario EL III Elemental analyzer. The dyeing operation was carried out using Wemer Mathis AG Textimaschine-Laborapparate CH-8155 Niederhasli/Zürich apparatus. Colour strength (K/S) of the dyed samples was measured by using OPTIMATCH 3100. The colour fastness to washing was determined using Launder-ometer. Colour fastness to rubbing was determined using Crock-Meter Type FD II and colour fastness to perspiration was determined using Prespiration Tester. The light fastness test was measured by using Mercury-Tungsten lamp.

Colour Strength
Colour strength of the dyed samples expressed as (K/S) was measured at λ max = 400 nm (Table 1).

Fastness Properties
The colour fastness to washing, rubbing (dry and wet crocking) and perspiration was determined according to the standard method [49]. Data are indicated in Table 1.

Colour Fastness to Washing
The composite specimens were sewed between two pieces of bleached cotton fabric and then immersed into an aqueous solution containing 5g/L soap non-ionic detergents at liquor ratio 50:1 and 2g/L sodium carbonate. The bath was thermostatically adjusted to 90 °C for 30 min; then samples were removed, rinsed twice with occasional hand squeezing, then dried. Evaluation of the wash fastness was established using the Grey-scale for colour change (Table 1).

Colour Fastness to Rubbing
The test is designed for determining the degree of colour, which may transfer from the surface of the coloured fabric to another surface, by rubbing.
Dry crocking test: The test specimen was placed flat on the base of the crock-meter. A white testing cloth was mounted. The covered finger was lowered on to the test specimen and caused to slide 20 times back and forth by making ten complete turns at a rate of one turn/sec. The white test sample was then removed for evaluation using the Grey-scale for staining.
Wet crocking test: The white test sample was thoroughly wetted out in water to a 65% and then picked up. The procedure was run as above. The white test samples were air dried before evaluation.

Colour Fastness to Perspiration
Two artificial perspiration solutions were prepared according to the following: Acidic solution: L-Histidine monohydrochloride monohydrate (0.5 g), sodium chloride (5 g) and sodium dihydrogen phosphate-1-hydrate (2.2 g) were dissolved in one liter distilled water. The pH was adjusted to 5.5 by 0.1N sodium hydroxide solution.
Alkaline solution: L-Histidine monohydrochloride monohydrate (0.5 g), sodium chloride (5 g) and di-sodium hydrogen phosphate-2-hydrate (2.5 g) were dissolved in one liter distilled water. The pH was adjusted to 8 by 0.1N sodium hydroxide solution.
The coloured specimen was sewed between two pieces of bleached cotton specimen. The composite sample was then immersed for 30 min. in the acidic perspiration solution at 37 °C (±2) with occasional agitation and squeezing to insure complete wetting. The test specimen was placed between two plastic plates under a force of about 5 Kg. The plates containing the composite specimens were left for about 6-8 hours. The same experiment was followed with another composite sample using the alkaline perspiration solution. The effect on the colour of the test specimen was expressed and defined by reference to Grey-scale for color change.

Colour Fastness to Light
The light fastness test was assessed in accordance with test method (ISO 105-A03). Using Mercury-Tungsten lamp, (continuous light) for 40 hours. The effect on the colour of the test samples was expressed and defined by reference to Grey-scale for colour change.

Antimicrobial Activity of the Synthesized Dyed and Dye Intermediate
Microorganisms used were obtained from Microbial Chemistry Department, National Research Center, Cairo, Egypt. For the in vitro antimicrobial activity evaluation, microorganism suspensions were prepared to contain approximately 108 cuf/mL and the plates were inoculated. A stock solution of each of the synthesized compounds (1.0 mg/mL) in DMSO was prepared and graded dilutions of the tested compounds were incorporated in a cavity (depth 3 mm, diameter 4 mm) made in the center of the Petri dish (nutrient agar for bacteria and Sabouraud vs. dextrose agar medium for fungi). The plates were incubated in duplicates for 24 h at 37 °C (for bacteria) and at 30 °C (for fungi). A positive control using only inoculation and a negative control using only DMSO in the cavity were carried out. The results of antimicrobial screening of the synthesized and standard antibiotics are given in Table 2

Antimicrobial Activity Test
Disc diffusion method with some modifications was used for screening the nylon 66, acetate and polyester fabric samples for antimicrobial activity [52]. Nutrient agar (for bacteria) or malt agar (for yeast) plates were inoculated with 0.1 mL of an appropriate dilution of the tested culture. Test fabric samples (1 cm diameter) were placed on the surface of the inoculated plates. The plates were incubated at the appropriate temperature for 24 h. Diameter of inhibition zone (mm) including the disc diameter was measured for each treatment. The result of antimicrobial activity of the tested dyed fabric are given in Table 3.

Conclusions
Our synthetic strategy provides a simple protocol for producing dyes and dye precursors based on conjugate enaminones and/or enaminonitriles with potent dyeing and/or antimicrobial finishing capabilities. The novel compounds could be lead for the development of new functional materials with special finish properties for textile fabrics. Moreover, the results of the present study may point that the novel products could be useful as synthetic precursors for azo-and azomethine ligands or polymethine dyes which may be suitable for both electronic and optical applications. It is clear that fabrics dyed or treated with the synthesized novel systems exhibit significant antimicrobial activity. This is due to the inherent antimicrobial character of the dyes or dye precursors. The presence of an oxo moiety which could be responsible to complex or bind with nucleophilic amino acids in proteins leads to inactivation of the protein and loss of function. Moreover, formation of H-bonds with water molecules enable these compounds to more readily form positive ions, thereby inhibition of microbial growth by adsorption onto bacterial surface. As a consequence, we can conclude that the newly synthesized systems could be accepted as promising to develop new antibacterial compounds.