Synthesis, spectroscopic, and molecular structure characterizations of some azo derivatives of 2-hydroxyacetophenone

Journal of Molecular Structure 932 (2009) 43–54

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Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc

Synthesis, spectroscopic, and molecular structure characterizations of some azo derivatives of 2-hydroxyacetophenone d _ _ Çig˘dem Albayrak a,*, Ismail E. Gümrükçüog˘lu b, Mustafa Odabasßog˘lu c, Nazan Ocak Iskeleli , Erbil Ag˘ar b a

Faculty of Education, Sinop University, 57000 Sinop, Turkey Department of Chemistry, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Kurupelit-Samsun, Turkey c Chemistry Program., Pamukkale University, 20159 Kınıklı-Denizli, Turkey d Department of Science Education, Ondokuz Mayıs University, 55200 Samsun, Turkey b

a r t i c l e

i n f o

Article history: Received 11 March 2009 Received in revised form 21 May 2009 Accepted 21 May 2009 Available online 31 May 2009 Keywords: Azobenzene Azo dyes X-ray analysis Spectral characterization 2-Hydroxyacetophenone

a b s t r a c t Some novel azo compounds were prepared by the reaction of 2-hydroxyacetophenone with aniline and its substituted derivatives. The structures of synthesized azo compounds were determined by IR, UV–Vis, 1 H NMR and 13C NMR spectroscopic techniques and the structures of some of these compounds were also determined by X-ray diffraction studies. Structural analysis using IR in solid state shows that the azo form is favoured in the azo compounds whereas UV–Vis analysis of the azo compounds in solution has shown that there is a azo and ionic form. The azo compounds in the basic solvents dimethylformamide (DMF) and dimethylsulfoxide (DMSO) are both azo and ionic form while these compounds in ethyl alcohol (EtOH) and chloroform (CHCl3) are only azo form. Ó 2009 Elsevier B.V. All rights reserved.

1. Introduction

2. Experimental

Azo compounds are the oldest and largest class of industrially synthesized organic dyes due to their versatile application in various fields, such as dyeing textile fiber, biomedical studies, advanced application in organic synthesis and high technology areas as laser, liquid crystalline displays, electro-optical devices and ink-jet printers [1–3]. There are about three thousand azo dyes currently in use all over the world. The great majority of them are monoazo compounds, which have the common structure unit of the azo chromophore, –N@N–, linking two aromatic systems. The textile industry is the largest consumer of dyestuffs. Although some azo dyes have been reported to be toxic, dozens of additional monoazo dyes are permitted in drugs and cosmetics [4]. The pharmaceutical importance of the compounds including an arylazo group has been extensively reported in the literature [5,6]. The oxidation–reduction behaviors of these compounds play an important role in its biological activity [7]. Our interest has been focused on preparation of some azo compounds and investigation of their spectroscopic properties, molecular structure.

2.1. Synthesis

* Corresponding author. Fax: +90 368 271 55 30. E-mail address: [email protected] (Ç. Albayrak). 0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2009.05.043

Azo derivatives of (E)-2-acetyl-4-(phenyldiazenyl)phenol 4 were synthesized by the azo-coupling reactions of substituted benzenediazonium salts 2 with 2-hydroxyacetophenone 3 shown in Scheme 1 and Table 1. Substituted anilines 1 were diazotized using sodium nitrite in the presence of hydrochloric acid followed by coupling with 2-hydroxyacetophenone 3 to give (E)-2-acetyl-4(phenyldiazenyl)phenol dyes 4 in good yield. The (E)-2-acetyl-4(phenyldiazenyl)phenol 4 were purified by recrystallization from suitable solvents as mentioned below. A mixture of aniline (4 g, 42.9 mmol), water (20 ml) and concentrated hydrochloric acid (10.7 ml, 128 mmol) was stirred until a clear solution was obtained. This solution was cooled down to 0–5 °C and a solution of sodium nitrite (2.96 g, 60.06 mmol) in water was added dropwise while the temperature was maintained below 5 °C. The resulting mixture was stirred for 30 min in an ice bath. 2-hydroxyacetophenone (5.8 g, 42.9 mmol) solution (pH 9) was gradually added to a cooled solution of benzenediazonium chloride, prepared as described above, and the resulting mixture was stirred at 0–5 °C for 60 min in ice bath. The product was recrystallized from ethyl alcohol to obtain solid (E)-2-Acetyl-4(phenyldiazenyl)phenol. Crystals of (E)-2-Acetyl-4-(phenyldiazenyl)phenol were obtained after one day by slow evaporation from acetic acid (yield 78%, m.p. 114–115 °C).

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Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

Schmadzu spectrometer. Absorbtion spectra were determined on Unicam UV–Vis spectrometer. The 1H NMR and 13C NMR spectra were taken on Bruker AC 200 MHz spectrometer. Crystal structure results were taken with STOE IPDS II diffractometer. Elemental analysis was recorded by TUBITAK Ankara test and analysis laboratory. 3. Results and discussion 3.1. UV–Vis absorption spectra Scheme 1. Some azo compounds synthesized from 2-hydroxyacetophenone.

2.2. Instrumentation All melting points were taken with an electrothermal melting point apparatus. FT-IR spectra were recorded on FTIR-8900

The UV–Vis electronic spectra of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4 in various organic solvents (DMSO, DMF, EtOH and CHCl3) were recorded in the wavelength range 200–600 nm. Typical characteristic UV–Vis absorption bands of (E)-2-acetyl-4(phenyldiazenyl)phenols 4 in DMSO, DMF, EtOH and CHCl3 are given in Table 2. Representative spectra are shown in Figs. 1 and 2. Examination of the results indicates that the UV–Vis electronic

Table 1 Properties of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4. Compound

4a 4b 4c 4d 4e 4f 4g 4h 4i 4j 4k 4l 4m 4n 4o 4p 4r 4s 4t 4u

Yield (%)

78 84 86 80 79 84 52 55 78 74 45 83 56 45 40 58 63 67 56 88

Mp (°C)

%C

114–115 141–143 148–150 151–153 112–114 172–174 150–152 116–118 185–187 195–197 104–106 137–139 88–90 77–79 82–83 148–150 102–104 127–128 135–137 179–181

%H

%N

Found

Calculated

Found

Calculated

Found

Calculated

69.62 64.38 64.82 60.84 60.84 60.66 52.43 52.36 52.24 46.12 70.64 70.15 70.83 72.78 72.64 66.65 66.22 66.54 66.98 59.25

(69.99) (65.11) (65.11) (61.21) (61.21) (61.21) (52.69) (52.69) (52.69) (45.92) (70.85) (70.85) (71.62) (72.32) (72.95) (66.66) (66.66) (66.66) (67.59) (58.95)

5.661 4.004 3.738 3.929 3.684 3.480 3.142 3.230 2.873 2.952 5.140 4.680 6.59 6.44 6.94 5.140 4.443 5.381 6.140 4.16

(5.03) (4.29) (4.29) (4.04) (4.04) (4.04) (3.47) (3.47) (3.47) (3.03) (5.55) (5.55) (6.01) (6.43) (6.80) (5.22) (5.22) (5.22) (5.67) (3.89)

11.53 10.74 10.82 10.12 10.04 10.12 8.72 8.70 8.696 7.12 10.84 10.86 10.13 9.56 9.39 10.12 10.34 10.31 9.842 14.47

(11.66) (10.85) (10.85) (10.20) (10.20) (10.20) (8.78) (8.78) (8.78) (7.65) (11.02) (11.02) (10.44) (9.92) (9.45) (10.36) (10.36) (10.36) (9.85) (14.73)

Table 2 UV–Vis absorption bands of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4. Compounds

4a 4b 4c 4d 4e 4f 4g 4h 4i 4j 4k 4l 4m 4n 4o 4p 4r 4s 4t 4u

EtOH

CHCl3

DMSO

DMF

Azo

Anion

Azo

Anion

Azo

Anion

Azo

Anion

335(38600) 341(39200) 336(41000) 341(32600) 340(47200) 341(41200) 344(33600) 342(36100) 342(52000) 350(55200) 339(41700) 339(35000) 341(50100) 342(59800) 342(63900) 356(37500) 337(35800) 352(52900) 353(47100) 365(37900)

– – – – – – – – – – – – – – – – – – – –

337(27700) 343(31200) 338(30300) 343(29900) 340(28300) 345(30800) 344(35600) 344(34000) 347(32400) 350(44800) 338(33700) 341(34300) 344(37800) 342(38000) 342(38100) 354(30000) 340(24700) 354(63900) 357(30800) 366(37000)

– – – – – – – – – – – – – – – – – – – –

346(37000) 353(37400) 351(16800) 364(36400) 352(25400) 352(36500) 374(20100) 353(40200) 356(36100) 358(42000) 344(44200) 374(30200) 351(30600) 350(38100) 349(38400) 368(26900) 345(45400) 360(50500) 364(34100) 373(28600)

463(35400) 473(19000) 464(19900) 477(22500) 477(17100) 473(12800) 480(33200) 474(16800) 477(25000) 467(9600) 443(5200) 462(39700) 452(6000) 445(6500) 453(5400) 453(7600) 464(16300) 444(6200) 461(13400) 553(19300)

344(16600) 400(20600) 400(27400) 368(18400) 396(19400) 369(19100) 382(18100) 392(16100) 355(28300) 361(25200) 342(24000) 348(28300) 355(19300) 360(19100) 352(21800) 391(22700) 358(19300) 359(37500) 363(30300) 380(14900)

464(17200) 476(54400) 464(55400) 480(32900) 479(59000) 476(37800) 479(33200) 480(43000) 477(26100) 478(26900) 460(13300) 461(24200) 464(25100) 463(30000) 463(26200) 466(30200) 466(20000) 448(11000) 459(17300) 557(70200)

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

Fig. 1. The electronic spectra of 4a in (- - -) DMSO, (    ) DMF, (– –) CHCl3, (—) EtOH.

45

Fig. 3. The electronic spectra of 4a in DMF (—) and DMF + N-methylpiperazine (– –) for 6  105 M.

Fig. 2. The electronic spectra of 4a in DMF. (—) 6  105 M, (- - -) 4  105 M, (– –) 2  105 M, (–  –) 1  105 M. Fig. 4. The electronic spectra of 4u in (- - -) DMSO, (    ) DMF, (– –) CHCl3, (—) EtOH.

Scheme 2. Two different forms of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4 in solution.

spectra of (E)-2-acetyl-4-(phenyldiazenyl)phenol 4a are largely dependent on both the nature of the solvent employed and the concentration of solute dye. In the UV–Vis spectra of these compounds two absorbtion bands are noteworthy in DMF and DMSO whereas in ethanol and chloroform only one absorption band were observed (Fig. 1). The first band is at 330–400 nm and the second band is between 400 and 500 nm. The UV–Vis spectra of (E)-2-acetyl-4-(phenyldiazenyl)phenol 4a in the basic solvents DMF showed an increase the absorbtion band at 400–500 nm with decreasing concentration of (E)-2-acetyl-4-(phenyldiazenyl)phenol 4a whereas a diminution

the absorbtion band at 300–400 nm with decreasing concentration of (E)-2-acetyl-4-(phenyldiazenyl)phenol 4a (Fig. 2). The additional absorbtion band appearing in DMF and DMSO could be assigned to absorbtion by the ionized form of the compound (Scheme 2). This is substantiated by the fact that the band due to anion increases with decreasing concentration of 4a. The appearance of this band only in DMF and DMSO is due to the high basicity of these solvents [8,9]. Evidence for effect of the basicity of DMF is recorded the spectrum by dropping N-methylpiperazine in DMF where the band at 400–500 nm is observed while the absorbtion band at 300– 400 nm almost disappears (Fig. 3). Accordingly, the longer wavelength absorbtion band at 400–500 nm appearing in DMF and DMSO solutions is due to absorbtion by ionic form of these compounds. (E)-2-Acetyl-4-(4-nitrophenyldiazenyl)phenol 4u including electron-withdrawing substituent –NO2 group stabilize ionic form by delocalizing the negative charge, thus making the azo molecule more

46

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

acidic. For this reason, (E)-2-acetyl-4-(4-nitrophenyldiazenyl) phenol 4u is more ionic form than the other azo compounds (Fig. 4). (E)-2-Acetyl-4-(4-methoxyphenyldiazenyl)phenol 4s with electron-donating substituent –OCH3 group are less acidic because this substituent destabilize the ionic form and (E)-2-acetyl-4-(4-methoxyphenyldiazenyl)phenol 4s is less ionic form than the other azo compounds (Fig. 5). 3.2. IR absorption spectra The characteristic IR absorption bands of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4 were determined in KBr disk. In the IR spectra (Table 3) of these compounds two bands are noteworthy, one in the region 1630–1650 cm1 attributed to m(C@O) and the other in the region 1409–1433 cm1 attributed to the m(N@N) stretching frequencies. In the IR spectra of the parent acetophenone showed the presence of m(C@O) at 1686 cm1 which shifted to lower frequencies 1630–1650 cm1 in the noval azo compounds due to the formation of strong intramolecular hydrogen bonding O– H  O in the structure. The IR spectra of these compounds showed

Fig. 5. The electronic spectra of 4s in (- - -) DMSO, (    ) DMF, (– –) CHCl3, (—) EtOH.

Table 3 Characteristic IR absorption bands of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4. Compound R

mO–H (stretching) cm1

mO–H (bending) cm1

mC@O (stretching) cm1

mC–O (stretching) cm1

mN@N (stretching) cm1

H (4a) 2-F (4b) 4-F (4c) 2-Cl (4d) 3-Cl (4e) 4-Cl (4f) 2-Br (4g) 3-Br (4h) 4-Br (4i) 4-I (4j) 3-Me (4k) 4-Me (4l) 4-Et (4m) 4-Prn (4n) 4-Bun (4o) 2-OCH3 (4p) 3-OCH3 (4r) 4-OCH3 (4s) 4-OEt (4t) 4-NO2 (4u)

2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000 2000–3000

1326 1324 1330 1330 1326 1329 1330 1326 1328 1327 1322 1327 1327 1317 1317 1327 1330 1322 1326 1318

1637 1640 1647 1638 1638 1641 1639 1641 1639 1642 1638 1637 1646 1645 1646 1636 1638 1639 1640 1647

1216 1215 1221 1217 1213 1218 1217 1212 1216 1212 1210 1221 1223 1202 1202 1219 1218 1207 1213 1206

1418 1414 1422 1417 1409 1418 1417 1424 1417 1420 1423 1423 1429 1424 1425 1430 1433 1429 1420 1424

Fig. 6. The IR spectrum of 4c.

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

Fig. 7. The 1H NMR spectrum of 4c.

Fig. 8. The 1H NMR spectrum of 4c.

47

48

Table 4 1 H NMR signals of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4.

3

2

4 R

1 5

12

N

6

N

11

7

10 9

O 13

R

H2

H3

H4

H5

H6

H8

H11

H12

H13

H14

CH2

CH2

CH2

CH3

H (4a)

7.816(dd) J23 = 8.754 J24 = 1.644

7.541(t) J32 = 8.754 J34 = 8.754

7.507(tt) J43 = 8.754 J45 = 8.754 J42 = 1.644 J46 = 1.644

7.541(t) J56 = 8.754 J54 = 8.754

7.816(dd) J65 = 8.754 J64 = 1.754

8.327 (d) J812 = 2.378

7.089 (d) J1112 = 8.906

7.984(dd) J1211 = 8.906 J128 = 2.378

2.68

12.287

–

–

–

–

2-F (4b)

–

7.715(td) J34 = 7.966 JHF = 7.966 J35 = 1.734

7.473(tdd) J43 = 7.966 J45= 7.966 JHF = 1.734 J46= 1.502

7.334(td) J56 = 7.966 J54 = 7.966 JHF = 1.734

7.589(ddd) J65 = 7.966 JHF = 3.06 J64 = 7.966

8.409(d) J812 = 2.452

7.160 (d) J1112 = 8.938

8.042(dd) J1211 = 8.938 J128 = 2.452

2.727

12.327

–

–

–

–

4-F (4c)

7.924(dd) J23 = 8.84 JHF = 5.358

7.406(t) J32 = 8.84 JHF = 8.84

–

7.406(t) J56 = 8.84 JHF = 8.84

7.924(dd) J65 = 8.84 JHF = 5.358

8.373 (d) J812 = 2.372

7.140(d) J1112 = 8.910

8.027 (dd) J1211 = 8.910 J128 = 2.372

2.719

12.243

–

–

–

–

2-Cl (4d)

–

7.626(dd) J34 = 7.334 J35 = 1.96

7.509(td) J43 = 7.334 J45 = 7.334 J46 = 1.96

7.437(td) J56 = 7.334 J54 = 7.334 J53 = 1.96

7.662(dd) J65 = 7.334 J64 = 1.96

8.390(d) J812 = 2.148

7.138(d) J1112 = 8.924

8.01(dd) J1211 = 8.924 J128 = 2.148

2.702

12.319

–

–

–

–

3-Cl (4e)

7.821(t) J26 = 2.348 J24 = 2.348

–

7.792(dt) J45 = 7.890 J42 = 2.348 J46 = 2.348

7.583(t) J56 = 7.890 J54 = 7.890

7.567(dt) J65 = 7.890 J64 = 2.348 J62 = 2.348

8.367(d) J812 = 2.420

7.110 (d) J1112 = 8.93

7.997(dd) J1211 = 8.93 J128 = 2.420

2.694

12.319

–

–

–

–

4-Cl (4f)

7.622 (d) J23 = 8.696

7.861(d) J32 = 8.696

–

7.861(d) J56 = 8.696

7.622 (d) J65 = 8.696

8.377 (d) J812 = 2.402

7.138 (d) J1112 = 8.926

8.032 (dd) J1211 = 8.926 J128 = 2.402

2.713

12.294

–

–

–

–

2-Br (4g)

–

7.6065(d) J34 = 7.8

7.431(t) J43 = 7.8 J45 = 7.8

7.494(t) J56 = 7.8 J54 = 7.8

7.8335(d) J6 5 = 7.8

8.412 (d) J812 = 2.4

7.156 (d) J1112 = 8.8

8.022 (dd) J1211 = 8.8 J128 = 2.4

2.71

12.32

–

–

–

–

3-Br (4h)

7.959(s)

–

7.717(d) J45 = 8.0

7.546(t) J54 = 8.0 J56 = 8.0

7.887(d) J65 = 8.0

8.422(s)

7.146(d) J1112 = 8.8

8.044(d) J1211 = 8.8

2.72

12.32

–

–

–

–

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

8

OH14

7.798(s)

7.798(s)

–

7.798(s)

7.798(s)

8.410(d) J812 = 2.39

7.158(d) J1112 = 8.98

8.062 (dd) J1211 = 8.98 J128 = 2.39

2.728

12.31

–

–

–

–

4-I (4j)

7.633(d) J23 = 8.4

7.936(d) J32 = 8.4

–

7.936(d) J56 = 8.4

7.633(d) J65 = 8.4

8.391(d) J812 = 2.4

7.144(d) J1112 = 8.8

8.044 (dd) J1211 = 8.8 J128 = 2.4

2.72

12.29

–

–

–

-

3-Me (4k)

7.617 (s)

–

7.305 (d) J43 = 8.0

7.415(t) J54 = 8.0 J56 = 8.0

7.625(d) J65 = 8.0

8.332(d) J812 = 2.0

7.096(d) J1112 = 8.8

7.983 (dd) J1211 = 8.8 J128 = 2.0

2.69

12.27

–

–

–

2.37

4-Me (4l)

7.769(d) J23 = 7.774

7.374(d) J32 = 7.774

–

7.374(d) J56 = 7.774

7.769(d) J65 = 7.774

8.363 (d) J812 = 2.42

7.134 (d) J1112 = 8.90

8.029(dd) J1211 = 8.90 J128 = 2.42

2.7241

12.241

–

–

–

2.383

4-Et (4m)

7.765(d) J23 = 8.4

7.372(d) J32 = 8.4

–

7.372(d) J56 = 8.4

7.765(d) J65 = 8.4

8.338 (d) J812 = 2.4

7.111 (d) J1112 = 8.8

8.001(dd) J1211 = 8.8 J128 = 2.4

2.69

12.252

–

–

2.66 (q) J = 7.6

1.195 (t) J = 7.6

4-Prn (4n)

7.773(d) J23 = 8.0

7.366(d) J32 = 8.0

–

7.366(d) J56 = 8.0

7.773(d) J65 = 8.0

8.353 (d) J812 = 2.0

7.127 (d) J1112 = 8.8

8.016(dd) J1211 = 8.8 J128 = 2.0

2.717

12.242

–

2.616(t) J = 7.2

1.612 (h) J = 7.2

0.892 (t) J = 7.2

4-Bun (4o)

7.749(d) J23 = 8.4

7.337(d) J32 = 8.8

–

7.337(d) J56 = 8.8

7.749(d) J65 = 8.4

8.332(d) J812 = 2.0

7.109 (d) J1112 = 8.8

7.995(dd) J1211 = 8.8 J128 = 2.0

2.701

12.245

2.613 (t) J = 7.8

1.548 (p) J = 7.8

1.285 (h) J = 7.8

0.869 (t) J = 7.8

2-OMe (4p)

–

7.219(d) J34 = 7.2

7.463(t) J43 = 7.2 J45 = 7.2

7.000(t) J54 = 7.2 J56 = 7.2

7.497(d) J65 = 7.2

8.313

7.109(d) J1112 = 8.8

7.956(d) J1211 = 8.8

2.696

–

–

–

–

3.925

3-OMe (4r)

7.360(t) J24 = 1.322 J26 = 1.322

–

7.098 (dt) J45= 7.762 J42 = 1.322 J46 = 1.322

7.47641 (t) J56 = 7.762 J54 = 7.762

7.460dt) J65 = 7.762 J62 = 1.322 J64 = 1.322

8.368 (d) J812 = 2.414

7.117 (d) J1112 = 8.952

8.015 (dd) J1211 = 8.952 J128 = 2.414

2.709

12.29

–

–

–

3.821

4-OMe (4s)

7.852(d) J23 = 8.8

7.104(d) J32 = 8.8

–

7.104(d) J5 6 = 8.8

7.852(d) J65 = 8.8

8.322(d) J812 = 1.6

7.115 (d) J1112 = 8.8

7.998 (dd) J1211 = 8.8 J128 = 1.6

2.717

12.207

–

–

–

3.841

4-OEt (4t)

7.083(d) J23 = 8.826

7.839(d) J32 = 8.826

–

7.839(d) J56 = 8.826

7.083(d) J65 = 8.826

8.320 (d) J812 = 2.34

7.118 (d) J1112 = 8.88

8.001(dd) J1211 = 8.88 J128 = 2.34

2.713

11.976

–

–

4.107 J1516 = 6.88

1.343 J1615 = 6.88

4-NO2 (4u) J23 = 8.8

8.011(d) J32 = 8.8

8.386(d)

– J56 = 8.8

8.386(d) J65 = 8.8

8.011(d) J812 = 2.4

8.432 (d) J1112 = 8.8

7.158(d) J1211 = 8.8 J128 = 2.4

8.069(dd)

2.719

12.378

–

–

–

–

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

4-Br (4i)

49

50

Table 5 13 C NMR signals of (E)-2-acetyl-4-(phenyldiazenyl)phenols 4.

3

2

4 5

6

12

N N

11

7

10

OH

9

8

14

O

13 R

C1

C2

C3

C4

C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

CH2

CH2

CH2

CH3

H (4a) 4-F (4c)

151.82 148.61

131.10 163.63 JC4F = 252 132.44 131.28 135.69 134.17 133.90 124.57 98.80 132.15 141.41 144.91 144.96 144.93 133.00 117.46 162.90 161.16 148.57

129.39 116.287 JC5F = 22.9 129.27 130.66 124.16 127.97 131.97 132.62 138.83 129.57 130.01 129.14 129.75 129.64 116.71 130.32 115.02 115.10 123.70

122.36 124.540 JC6F = 9.1 117.67 120.70 129.71 124.79 122.98 124.35 124.66 115.09 122.45 122.91 122.82 122.83 120.93 116.21 124.76 124.46 125.50

128.08 127.92

121.07 121.28

163.01 162.98

118.80 118.87

127.85 127.92

28.30 28.42

174.94 174.99

–

–

–

–

147.91 152.85 150.22 149.16 153.35 150.86 151.60 152.30 149.94 150.51 150.57 150.50 141.70 150.10 146.47 146.02 155.57

129.39 116.43 JC3F = 22.9 130.86 134.24 124.16 132.93 123.47 132.62 138.83 139.27 130.01 129.14 129.75 129.64 113.77 160.10 115.02 115.10 123.70

144.45 144.38

2-Cl (4d) 3-Cl (4e) 4-Cl (4f) 2-Br (4g) 3-Br (4h) 4-Br (4i) 4-I (4j) 3-Me (4k) 4-Me (4l) 4-Et (4m) 4-Prn (4n) 4-Bun (4o) 2-OCH3 (4p) 3-OCH3 (4r) 4-OCH3 (4s) 4-OEt (4t) 4-NO2 (4u)

122.36 124.67 JC2F = 9.1 133.65 122.60 129.71 118.14 123.79 124.35 124.66 122.83 122.45 122.91 122.82 122.83 156.89 105.79 124.76 124.46 125.50

144.87 144.28 144.47 145.06 144.68 144.45 144.82 144.88 144.51 147.85 146.31 146.48 145.42 144.38 144.98 144.58 144.97

128.23 128.88 128.07 129.69 129.17 128.43 128.73 128.51 127.88 128.30 128.25 128.29 128.65 128.28 128.22 127.94 129.60

121.61 121.23 121.45 121.82 121.73 121.44 121.75 121.33 121.15 121.43 121.54 121.45 121.47 127.85 121.45 121.13 122.03

163.49 163.54 160.62 163.85 163.83 163.26 163.61 163.43 162.83 163.25 163.22 163.25 163.23 163.10 162.16 162.54 164.31

119.16 119.00 119.02 119.47 119.36 119.04 119.35 119.20 118.85 119.20 119.22 119.19 119.20 118.86 119.17 118.86 119.50

127.71 127.94 125.76 129.09 128.32 127.99 128.38 128.19 127.88 128.22 128.25 128.19 128.05 127.85 127.82 127.43 128.52

28.63 28.46 28.39 28.87 28.85 28.60 28.87 28.60 28.42 28.49 28.75 28.70 28.74 28.37 28.70 28.34 29.01

175.27 203.51 175.75 203.64 203.85 174.56 203.86 204.03 174.88 204.02 204.01 203.98 203.91 174.98 204.15 174.76 203.50

– – – – – – – – – – – 35.11 – – – – –

– – – – – – – – – – 37.47 33.32 – – – – –

– – – – – – – – – 28.70 24.29 22.21 – – – 63.77 –

– – – – – – – 21.32 21.08 15.72 14.04 14.19 56.38 55.37 56.06 14.68 –

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

R

1

51

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

Fig. 9.

13

C NMR spectrum of 4c. Table 6 Crystal data of 4c. Empirical formula Formula mass Crystal system Space group a (A) b (A) c (A) P (°) v (Å3) Z Pcalc. (g cm1) l (mm1) R1/wR2 (obsd data:2r(I)] R1/wR2 (all data) Goodness of fit

C14H11FN2O2 258.25 Orthorhombic Pna21 12.6706(9) 3.8698(2) 25.230(2) 90.00 1237.08(15) 4 1.39 0.105 0.039/0.080 0.062/0.087 0.888

Table 7 Fractional atomic coordinates and equivalent isotropic displacement parameters (Å2) ij U eq ¼ ð1=3RiRjU ai aj ai aj Þ.

Fig. 10.

13

C NMR spectrum of 4c.

also the presence of m(C–O) stretching in the region 1206– 1223 cm1 and also gave a band located at about 2000– 3000 cm1 assigned to m(O–H) frequency. All this values are in accordance with the literature [10,11]. Fig. 6 shows the IR spectrum of compound 4c. 3.3. NMR investigations The 1H NMR spectra of the azo compounds were recorded in DMSO-d6. The typical 1H NMR spectrum of the compound 4c is

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 N1 N2 O1 O2 F1

x

y

0.11688 (18) 0.1349 (2) 0.0588 (2) 0.0340 (2) 0.0543 (2) 0.02165 (17) 0.26150 (17) 0.24498 (17) 0.32210 (16) 0.41826 (16) 0.43418 (17) 0.35718 (16) 0.30541 (19) 0.2035 (2) 0.19983 (15) 0.17785 (14) 0.49717 (13) 0.37695 (16) 0.10834 (15)

0.5419 0.4495 0.5055 0.6558 0.7515 0.6957 0.4605 0.5539 0.5057 0.3545 0.2545 0.3048 0.6062 0.7571 0.4693 0.5296 0.2972 0.5621 0.7155

z (6) (7) (7) (7) (7) (6) (6) (5) (5) (6) (6) (6) (6) (7) (4) (5) (5) (5) (5)

0.35815 0.41036 0.44874 0.43300 0.38212 0.34454 0.23840 0.18664 0.14796 0.16382 0.21583 0.25278 0.09251 0.07490 0.32207 0.27431 0.12904 0.05974 0.47095

Ueq (9) (9) (10) (11) (10) (10) (9) (9) (9) (9) (9) (9) (9) (11) (8) (8) (9) (7) (7)

0.0480 0.0611 0.0712 0.0686 0.0621 0.0527 0.0457 0.0468 0.0484 0.0534 0.0548 0.0522 0.0573 0.0686 0.0511 0.0501 0.0787 0.0889 0.1083

(5) (7) (8) (7) (6) (6) (5) (5) (5) (6) (6) (6) (6) (6) (5) (5) (6) (6) (6)

52

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

Table 8 Selected geometric parameters for 4c (Å, °).

Table 9 Some X-ray derivatives.

4c O1—C10 O2—C13 N1—N2 N2—C7 N1—C1 O1—C10—C11 O1—C10—C9 C8—C7—N2 C12—C7—N2 O2—C13—C9 C6—C1—N1 C2—C1—N1 C7—N2—N1—C1

1.349 (3) 1.239 (3) 1.259 (2) 1.420 (3) 1.418 (3) 117.6 (2) 121.6 (2) 116.38 (17) 124.2 (2) 119.6 (2) 124.8 (2) 115.9 (2) 179.29 (19)

Compound

parameters

of

Dihedral angle (°)

some

(E)-2-acetyl-4-(phenyldiazenyl)phenols

Intramolecular hydrogen bond

4

Ref.

0

4a 4c 4d 4e 4t

3.48(15) 1.26(8) 3.73(9) 0.73(16) 10.14(4)

Length (Å A)

Angle (°)

2.550(3) 2.535(3) 2.5327(19) 2.547(2) 2.555(4)

146 151(3) 146 146 146

[14] This paper [15] [16] [17]

shown in Fig. 7. In the 1H NMR spectra, all azo compounds 4 show one peak at 2.67–2.73 ppm which belongs to methyl protons of acetyl group. 1H NMR spectra of azo compounds show d peaks at 8.30–8.44 ppm, d at 7.09–7.17 ppm and dd at 7.95–8.1 ppm, which

Fig. 11. A view of 4c, with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Fig. 12. A partial diagram for 4c, with O–H  O, C–H  O and C–H  N hydrogen bonds and shown as dashed lines. The atom numbering scheme. H atom not involved in these interactions have been omitted. [symmetry codes: (i) 1/2  x, 1/2  y, z + 1/2; (ii) x + 1/2, y  1/2, z + 1/2; (iii) 1  x, 1  y, z + 1/2; (iv) 1/2  x, 3/2  y, z].

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

53

Fig. 13. A partial packing diagram for 4c, with O–H  O, C–H  O and C–H  N hydrogen bonds shown as dashed lines. The atom numbering scheme. H atom not involved in these interactions have been omitted. [symmetry codes: (i) 1/2  x, 1/2  y, z + 1/2; (ii) x + 1/2, 3/2  y, z; (iii) x + 1/2, 1/2  y, z].

Table 10 0 Hydrogen-bonding geometry (Å A, °) for 4c.

4c

a b c

D–H  A

D–H

H  A

D  A

D–H  A

O1–H1  O2 C3–H3  O2a C5–H5  N1b C11–H11  N2c

0.96(4) 0.93 0.93 0.93

1.65(4) 2.51 2.73 2.69

2.535(3) 3.384(3) 3.628(3) 3.594(3)

151(3) 157.1 163.7 165.6

1/2  x, y  1/2, 1/2 + z. x  1/2, 3/2y, z. 1/2 + x, 1/2  y, z.

are attributed to the phenyl group bearing acetyl group. The resonance of hydroxyl proton is at 11–12 ppm which is typical for intramolecular hydrogen bonding (O–H  O) proton. In contrast to the other p-substituted azo compounds, in 1H NMR spectra of 4c, since the F nucleus couples to H2, H6 and H3, H5 protons, they, respectively, give a quartet and a triplet (Fig. 8). Coupling constants for proton-fluorine are different because the fluorine atom couples differently to the ortho-, metaand para-protons. The triplet can be shown as a result of consecutive splitting of the H3, H5 absorbtion by the H2, H6 and F nucleus. The peaks overlap since the coupling constants are identical (JHF = J3,2 = 8.84 Hz). The H2, H6 protons are coupled to both the H3, H5 protons and F nucleus and show doublet of doublets (J2,3 = 8.84 Hz, JHF = 5.36 Hz). This result is in accordance with the literature [10,11]. The chemical shift values are shown in Table 4. In the 13C NMR spectra of azo compounds were recorded in DMSO carbonyl carbons (C14) in the azo compounds observed in the range 174–204 ppm, and phenolic carbons (C10) appear at 162–164 ppm. The chemical shifts of carbons for azo compounds

are shown in Table 5. The 13C NMR spectra of azo compounds show peaks at 127.7–128.9 ppm (C8), at 118.7–119.2 ppm (C11) and at 125.7–128 ppm (C12), which are attributed to phenyl group bearing acetyl functionality. The 13C NMR spectrum of 4c is shown in Fig. 9. As in the 1H NMR spectra of 4c, the F nucleus couples to carbons of fluorine-containing aromatic ring and C4 and C2,C6 and C3,C5 carbons give a doublet in the 13C NMR spectra (Fig. 10). Coupling constants for carbon–fluorine are different as the fluorine atom couples differently to the ipso-, ortho-, meta- and para-carbons. Coupling constants for carbon–fluorine are given in Table 5. This result is in accordance with the literature [10,11]. The chemical shift values of 4 compounds are summarized in Table 5. 3.4. Description of the crystal structures A summary of crystallographic data, experimental details, and refinement results for 4c are given in Table 6. The atomic coordinates with their isotropic displacement parameters of non-hydrogen atoms are listed in Table 7. Table 8 shows the selected bond distances and bond angles for 4c. SHELXS-97 [12] and SHELXL-97 [13] were used for the structure solution and refinement. The molecular structure of compound 4c is shown in Fig. 11 with the atom numbering scheme. The compound consists of two aromatic rings (C1–C6 and C7–C12), and an azo frame (C1– N1–N2–C7). In 4c, the aromatic rings, which adopt a trans configuration about the N@N double bond, are nearly coplanar, with a dihedral angle of 1.26(8)° between them. In our previous X-ray investigation, it has also been shown that, the other (E)-2-acetyl4-(phenyldiazenyl)phenols are nearly coplanar and the dihedral angles of these compounds are as in Table 9 [14–17].

54

Ç. Albayrak et al. / Journal of Molecular Structure 932 (2009) 43–54

The (E)-2-acetyl-4-(4-fluorophenyldiazenyl)phenol molecules are linked into [S(6)R44 (34)] motifs [18] (Fig. 12). A significant intramolecular interaction is noted, involving phenolic atom H and carbonyl atom O1, such that a six-membered ring is formed S(6) and the weak intermolecular C–H  O and C–H  N hydrogen bonds result in the formation R44 (34) ring motif (Fig. 12 and 13, Table 10). The C13–O1 double bond distance in 4c is also consistent with the value of the C@O double bond in carbonyl compounds [19]. The C10–O1, –N1@N2–, C1–N1 and C7–N2 bond lengths are consistent with values observed in related compounds [14–17,20–24]. 4. Conclusion In the present work, we report the synthesis and characterization of some substituted azo compounds using microanalyses (C,H,N), IR, UV–Vis, 1H and 13C NMR spectroscopic techniques. The structures of some of these compounds were determined by X-ray diffraction studies. In the IR spectra of substituted azo compounds, the m(C@O) and m(N@N) bands are observed at 1630– 1650 cm1 and 1409–1433 cm1, respectively. In the 13C NMR spectra of these azo compounds the carbonyl carbon (C14) resonates at 174–204 ppm. Furter data are presented in Table 5. In the 1H NMR spectra, the resonance of hydroxyl proton at 11–12 ppm is due to the presence of intramolecular hydrogen bonding m(O–H  O) frequencies in the structure. X-ray investigations show that the (E)-2-acetyl-4-(phenyldiazenyl)phenols the aromatic rings, which adopt a trans configuration about the N@N double bond are nearly coplanar. The (E)-2-acetyl-4-(4-fluorophenyldiazenyl)phenol molecules are linked into [S(6)R44 (34)] motifs. A significant intramolecular interaction is noted, involving phenolic atom H and carbonyl atom O, such that a six-membered ring is formed. Appendix Supplementary. material Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as the supplementary publication

no. CCDC 712626. Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44-1223-336033 or e-mail: [email protected]. ac.uk). Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.molstruc. 2009.05.043.

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