Synthesis, characterization and DFT computational studies of new heterocyclic azo compounds European Journal of Chemistry 9 (2) (2018) 84-88 European Journal of Chemistry View Journal Online View Article Online Synthesis, characterization and DFT computational studies of new heterocyclic azo compounds Faeza Almashal *, Abeer Mohamed Jabar and Adil Muala Dhumad ** College of Education for Pure Science, Basrah University, Basrah, 61004, Iraq fae71za@yahoo.com (F.A.), abmohammed2341992@gmail.com (A.M.J.), adilmuala2013@yahoo.com (A.M.D.) * Corresponding author at: College of Education for Pure Science, Basrah University, Basrah, 61004, Iraq. Tel: +964.771.7563147 Fax: +964.771.7563147 e-mail: fae71za@yahoo.com (F. Almashal) e-mail: adilmuala2013@yahoo.com (A.M. Dhumad) 10.5155/eurjchem.9.2.84-88.1683 Received: 26 January 2018 Received in revised form: 23 March 2018 Accepted: 04 April 2018 Published online: 30 June 2018 Printed: 30 June 2018 New heterocyclic azo compounds were prepared by coupling the diazonium salts with N-(4- methylphenyl)maleimide with various different sulfa compounds. The structure of heterocyclic azo compounds was determined by MS, FT-IR and 1H NMR techniques. The density function theory calculation at the B3LYP method with 6-311G(d,p) basis set is used to investigate the electronic structures of the prepared heterocyclic azo compounds. Mulliken charge distributions and HOMO-LUMO energies of the mentioned compounds have been also computed by same method and basis set. B3LYP Mulliken charge Azo sulfonamides Electronic structures Density function theory Heterocyclic azo compound Cite this: Eur. J. Chem. 2018, 9(2), 84-88 Journal website: www.eurjchem.com 1. Introduction Azo compounds acquired wide interest in application to biological system [1]. In pharmaceuticals, azo linkage was used to protect drug from undesirable reaction, such as prontosil was found to protect against, and cure streptococcal infections in mice. Interestingly prontosil was inactive on bacterial cultures. Prontosil is totally in active in vitro but possesses excellent activity in vivo [2,3]. The azo compounds are applicable in biocidal treatment of textile materials because they exhibit biological activity [4]. Azo compounds are well known for their medicinal importance and are recognized for their applications as antiseptics, antidiabetics, antibacterial, and antitumor [5-10]. Azo compounds are also involved in a many biological reactions such as carcinogenesis, protein synthesis and inhibition of DNA [11-15]. In the chemical industry, aromatic azo compounds are widely used as pigments [16], food additives, indicators, [17] radical reaction initiators [18] and therapeutic agents [19]. Moreover, azo compounds considered promise in electronics [20] and drug delivery [21]. The first effective antibacterial drugs that could be used systemically for the cure of bacterial infection in humans were containing the azo sulfonamides compounds [22]. The present paper reports on the synthesis of a series of heterocyclic azo compounds containing the sulfonamide functional group. The chemical structures of the heterocyclic azo compounds were studied using spectral methods and theoretical calculations. 2. Experimental 2.1. Instrumentation All the chemicals were used as received without further purification except for aniline, was distilled before use. FT-IR spectra were measured at room temperature using a Perkin- Elmer 2000 FT-IR equipped with a high-purity dried potassium bromide (KBr) beam splitter. The 1H NMR spectra were obtained using a Bruker 400 MHz NMR spectrometer with tetramethylsilane as the internal reference. The mass spectra were recorded on a Perkin Elmer Clarus 500 Gas Chromatography-Mass Spectrometry system (GC-MS). 2.2. Synthesis 2.2.1. Preparation of N-(4-methylphenyl)maleimide (I) ABSTRACT RESEARCH ARTICLE KEYWORDS European Journal of Chemistry ISSN 2153-2249 (Print) / ISSN 2153-2257 (Online) – Copyright © 2018 The Authors – Atlanta Publishing House LLC – Printed in the USA. This work is published and licensed by Atlanta Publishing House LLC – CC BY NC – Some Rights Reserved. http://dx.doi.org/10.5155/eurjchem.9.2.84-88.1683 http://dx.doi.org/10.5155/eurjchem.9.2.84-88.1683 https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.9.2.84-88.1683&domain=pdf&date_stamp=2018-06-30 http://www.eurjchem.com/ http://dx.doi.org/10.5155/eurjchem.9.2.84-88.1683 mailto:fae71za@yahoo.com mailto:abmohammed2341992@gmail.com mailto:adilmuala2013@yahoo.com mailto:fae71za@yahoo.com mailto:adilmuala2013@yahoo.com http://www.eurjchem.com/ https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.9.2.84-88.1683&domain=pdf&date_stamp=2018-06-30� Almashal et al. / European Journal of Chemistry 9 (2) (2018) 84-88 85 O O O + NH2 H3C N O O H3C H2N S + NaNO2 HCl / 5 °C NCl +N O O NH R S O O NH R NCl +N S O O NH R N O O CH3 NaOH / 5°C N O O CH3 NN S O O NH R R= C O H3C N N H3C CH3 H2N NH2 N N N N OCH3 N N H3C H N S N (I) (II) + H T1 T2 T3 T4 T5 T6 T7 T8 T9 Scheme 1 4-Methyaniline (0.15 mol) and maleic anhydride (0.15 mol) were dissolved separately in DMF (50 mL) to yield solutions A and B, respectively (Scheme 1). Solution B was added dropwise into solution A to give solution C. Solution C was stirred for 2 hours at 20 °C in a water bath. P2O5 (12 g) was dissolved in H2SO4 (10 mL) and DMF (70 mL). This mixture was added dropwise into solution C and was stirred for 2 hours at 70 °C. The mixture was kept chilled in the ice bath and poured into cold water. A precipitate formed that was filtered, washed with distilled water and finally recrystallized from 2-propanol and dried in a vacuum oven at 65 °C for 24 hours. M.p.: 151-153 °C [23]. 2.2.2. General procedure for preparation of the heterocyclic azo compounds (T1-T9) Solution A was prepared by mixing sulfa compounds (0.01 mol) with concentrated HCl (0.3 mL) and water (2 mL) and cooling at 5 °C in an ice bath. NaNO2 (0.69 g, 0.01 mol) was dissolved in water (2 mL) at 5 °C to obtain solution B. Then solution A was added dropwise to solution B at 5 °C with stirring. The mixture was then slowly added into the solution of N-(4-methylphenyl)maleimide (0.01 mol), which was dissolved in 10% NaOH (2 mL) at 5 °C. The mixture was keep chilled in the ice bath and stirred continuously for 10 min. The precipitate formed was filtered and recrystallized from ethanol and hexane in ratio (4:6). The procedure was repeated by substituted different sulfa compounds (Scheme 1). 4-((5-(2, 5-Dioxo-2, 5-dihydro-1H-pyrrol-1-yl)-2-methylphen yl)diazenyl)benzenesulfonamide (T1): Color: Light brown. Yield: 70%. M.p.: 176-178 °C. FT-IR (KBr, ν, cm-1): 3275 (N-H), 3095 (C-H Arom.), 2924 (C-H Aliph.), 1705 (C=O), 1635 (C=C), 1533 (N=N), 1161, 1327 (SO2), 1288 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.31 (s, 3H, CH3-Ph), 4.45 (s, 2H, CH=CH), 6.29 (s, 2H, Ar-H), 6.48 (s, 2H, Ar-H), 7.13 (d, J = 7.5 Hz, 1H, Ar-H), 7.50 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 7.52 (s, 1H, Ar-H), 10.41 (s, 2H, NH2). MS (EI, m/z (%)): 370 (M+, 100). N-((4-((5-(2, 5-Dioxo-2, 5-dihydro-1H-pyrrol-1-yl)-2-methyl phenyl)diazenyl)phenyl)sulfonyl)acetamide (T2): Color: Brown. Yield: 65%. M.p.: 178-179 °C. FT-IR (KBr, ν, cm-1): 3285 (N-H), 3094 (C-H Arom.), 2924 (C-H Aliph.), 1701 (C=O), 1636 (C=C), 1528 (N=N), 1153, 1329 (SO2), 1265 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 1.93 (s, 3H, CH3-CO-N), 2.26 (s, 3H, CH3-Ph), 6.29 (d, J = 7.5 Hz, 1H, CH-CH), 6.47 (d, J = 7.5 Hz, 1H, CH-CH), 7.15 (dd, J = 7.5, 1.5 Hz, 2H, Ar-H), 7.53 (d, J = 7.5 Hz, 2H, Ar-H), 7.95-7.51 (m, 3H, Ar-H), 10.32 (s, 1H, NH). MS (EI, m/z (%)): 412 (M+, 100). N-(4, 6-Dimethylpyrimidin-2-yl)-4-((5-(2, 5-dioxo-2, 5-dihyd ro-1H-pyrrol-1-yl)-2-methyl-phenyl)diazenyl)benzenesulfonami- de (T3): Color: Yellow. Yield: 67%. M.p.: 188-190 °C. FT-IR (KBr, ν, cm-1): 3275 (N-H), 3091 (C-H Arom.), 2918 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1531 (N=N), 1182, 1327 (SO2), 1267 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.25 (s, 6H, Pyr-2CH3), 2.31 (s, 3H, CH3-Ph), 7.04 (s, 1H, Pyr-H), 7.46 (d, J = 7.5 Hz, 1H, Ar-H), 7.65 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 7.86 (s, 2H, Ar-H), 8.18-8.09 (m, 5H, Ar-H), 9.00 (s, 1H, NH). MS (EI, m/z (%)): 476 (M+, 100). N-(Diaminomethylene)-4-((5-(2, 5-dioxo-2, 5-dihydro-1H- pyrrol-1-yl)-2-methylphenyl)di-azenyl)benzenesulfonamide (T4): Color: Light yellow. Yield: 58%. M.p.: 184-185 °C. FT-IR (KBr, ν, cm-1): 3284 (N-H), 3093 (C-H Arom.), 2915 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1523 (N=N), 1183, 1328 (SO2), 1269 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.31 (s, 3H, CH3-Ph), 7.32 (s, 2H, CH=CH), 7.46 (s, 4H, 2×NH2), 8.18 (m, 2H, Ar-H), 8.20 (m, 3H, Ar-H), 8.27 (dd, J = 7.5, 1.5 Hz, 1H, Ar- H), 8.61 (d, J = 7.5, 1.5 Hz, 1H, Ar-H). MS (EI, m/z (%)): 412 (M+, 100). 4-((5-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)-2-methylphen- yl)diazenyl)-N-(pyrimidin-2-yl)benzenesulfonamide (T5): Color: 2018 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.9.2.84-88.1683 86 Almashal et al. / European Journal of Chemistry 9 (2) (2018) 84-88 Light yellow. Yield: 58%. M.p.: 184-185 °C. FT-IR (KBr, ν, cm-1): 3284 (N-H), 3093 (C-H Arom.), 2924 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1527 (N=N), 1182, 1329 (SO2), 1267 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.31 (s, 3H, CH3-Ph), 7.06 (t, J = 7.5 Hz, 1H, Pyr-H), 7.46 (d, J = 7.6 Hz, 1H, Ar-H), 7.65 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 7.86 (s, 2H, CH=CH), 8.18-8.09 (m, 5H, Ar-H), 8.58 (d, J = 7.5 Hz, 2H, Pyr-H), 9.00 (s, 1H, NH). MS (EI, m/z (%)): 448 (M+, 100). 4-((5-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)-2-methylphen- yl)diazenyl)-N-(6-methoxy-pyridazin-3-yl) benzenesulfonamide (T6): Color: Orange. Yield: 60%. M.p.: 181-183 °C. FT-IR (KBr, ν, cm-1): 3284 (N-H), 3080 (C-H Arom.), 2924 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1529 (N=N), 1182, 1330 (SO2), 1264 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.31 (s, 3H, CH3-Ph), 3.84 (s, 3H, O-CH3), 7.16-7.06 (m, 2H, Ar-H), 7.46 (d, J = 7.6 Hz, 1H, Ar-H), 7.65 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 7.86 (s, 2H, CH=CH), 8.18-8.09 (m, 3H, Ar-H), 8.58 (d, J = 7.5 Hz, 2H, Pyr- H), 9.00 (s, 1H, NH). MS (EI, m/z (%)): 478 (M+, 100). 4-((5-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)-2-methylphen- yl)diazenyl)-N-(4-methylpyrimidin-2-yl)benzenesulfonamide (T7): Color: Yellow. Yield: 38%. M.p.: 191-192 °C. FT-IR (KBr, ν, cm-1): 3284 (N-H), 3091 (C-H Arom.), 2960 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1531 (N=N), 1180, 1327 (SO2), 1267 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.37 (s, 3H, CH3-Ph), 2.57 (s, 3H, Pyr-CH3), 7.20 (d, J = 7.5 Hz, 1H, Ar-H), 7.46 (d, J = 7.6 Hz, 1H, Ar-H), 7.65 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 7.86 (s, 2H, CH=CH), 8.18-8.09 (m, 4H, Ar-H), 8.88 (d, J = 7.5 Hz, 2H, Pyr-H), 9.00 (s, 1H, NH). MS (EI, m/z (%)): 462 (M+, 100). 4-((E)-(5-(2, 5-dioxo-2, 5-dihydro-1H-pyrrol-1-yl)-2-methyl phenyl)diazenyl)-N-((E)-thiazol-2(3H)-ylidene) benzenesulfon- amide (T8): Color: Light gray. Yield: 55%. M.p.: 180-182 °C. FT-IR (KBr, ν, cm-1): 3284 (N-H), 3091 (C-H Arom.), 2922 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1527 (N=N), 1143, 1327 (SO2), 1267 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.38 (s, 3H, CH3-Ph), 6.10 (d, J = 11.0 Hz, 1H, NH-CH=C), 6.86 (d, J = 11.0 Hz, 1H, S-CH=C), 7.03 (d, J = 10.8 Hz, 1H, Ar-H), 7.18 (d, J = 10.8 Hz, 1H, Ar-H), 7.33 (d, J = 7.5 Hz, 2H, Ar-H), 7.86 (s, 2H, CH=CH), 8.13-8.08 (m, 2H, Ar-H), 8.21 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 10.90 (s, 1H, NH). MS (EI, m/z (%)): 453 (M+, 100). 4-((5-(2,5-Dioxo-2, 5-dihydro-1H-pyrrol-1-yl)-2-methylphen- yl)diazenyl)-N-(pyridin-2-yl)benzenesulfonamide (T9): Color: Yellow. Yield: 60%. M.p.: 186-189 °C. FT-IR (KBr, ν, cm-1): 3284 (N-H), 3089 (C-H Arom.), 2924 (C-H Aliph.), 1701 (C=O), 1635 (C=C), 1527 (N=N), 1182, 1328 (SO2), 1267 (C-N). 1H NMR (400 MHz, CDCl3, δ, ppm): 2.34 (s, 3H, CH3-Ph), 7.06-6.96 (m, 2H, Ar-H), 7.17 (d, J = 11.0 Hz, 1H, Ar-H), 7.32 (d, J = 7.5 Hz, 1H, Ar-H), 7.41 (ddd, J = 7.5 Hz, 1H, Ar-H), 7.73 (td, J = 8.0, 1.3 Hz, 1H, Ar-H), 7.94-8.02 (m, 4H, Ar-H), 8.05 (dd, J = 7.5, 1.5 Hz, 1H, Ar-H), 8.41 (dd, J = 5.1, 1.2 Hz, 1H, Ar-H), 8.70 (d, J = 1.5 Hz, 1H, Ar-H), 9.10 (s, 1H, NH). MS (EI, m/z (%)): 447 (M+, 100). 2.3. Computational details All computations were performed using the Gaussian09 [24] software package. Full geometry optimizations were carried out using the Density Function Theory at B3LYP level for studied compounds [25,26]. Properties and HOMO-LUMO energies of the studied compounds was calculated by the 6- 311+G(d,p) higher basis set level. Mulliken charge distribu- tions of the investigated compounds were also computed at same level of method. 3. Results and discussion 3.1. Synthesis and characterization The preparation of compounds T1-T9 is shown in Scheme 1. The structure of these compounds was confirmed by FT-IR, 1H NMR, and Mass spectrum. The most important charac- teristic band of the IR spectra of the prepared compounds T1- T9 is the appearance of the N-N group at 1523-1533 cm−1. This is a sign of the coupling reaction of the reactive coupling bands at 3022-3095 cm-1 are attributed to the stretching vibration of the aromatic C-H, as shown in the bands at 2887-2960 cm -1 is attributed to aliphatic C-H, as well as the appearance of bands at 1701-1705 cm-1 attributed to two groups C=O, and there is a band at 1143-1327 cm-1 due to symmetric and asymmetric stretching vibration of the SO2 group. The FT-IR data for compounds T1-T9 showed the same characteristic bands of the coupling agents I and II, namely imide, methyl, group, alkene, and p-substituted band while the presence of the azo (N=N) group band in 1533-1523 cm−1 range confirmed the success of the synthesis. The 1H NMR for azo compounds T2 has been chosen as typical example. In the 1H NMR spectrum of compound T2, the protons of the alkene group (HC=CH) and the protons of aromatic ring appeared at δ 6.48-6.29 ppm and δ 7.13-7.52 ppm, respectively. 3.2. Computational results 3.2.1. Geometrical optimization The visualization of the optimized geometrical structure and atomic labeling of compound T1 calculated by the B3LYP method with 6-311+G(d,p) basis set are given in Figure 1. Figure 1. Optimized structures of compound T1 calculated by the B3LYP method with 6-311+G(d,p) basis set with atom numbering. 3.2.2. Mulliken population analysis Dipole moment, molecular polarizability and bond properties are affected by atomic charges, therefore, the Mulliken atomic charge calculation has an important role in quantum chemistry [27]. Mulliken population analysis was performed using DFT/B3LYP calculation method with 6- 311+G(d,p) basis set for studied compounds. Graphical reorientations of Mulliken charge distributions of studied compounds T1-T9 is shown in Figure 2. As can be seen in Table 1, all the carbon atoms have a net positive charge. The obtained atomic charge shows that the N26 atom (which bonded with different substituted) has lower negative atomic charge (-0.2928) in compounds T1 and T2 than the other studied T3-T9 compounds which obtained -0.3133, -0.5415, - 0.2958, -0.3140, -0.3055, -0.5182 and -0.2932, respectively. The highest negative atomic charge was -0.5415 in compound T4, also compound T4 has higher negative oxygen atom charge, which obtained -0.5695. 3.2.3. Total energies, dipole moments and molecular orbitals analysis The HOMO energy represents the ability to donate an electron, LUMO energy as an electron acceptor represents the ability to obtain an electron [27]. The HOMO-LUMO energy calculations of the title compounds were performed using DFT/B3LYP method with 6-311+G(d,p) basis set for the studied compounds T1-T9. 2018 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.9.2.84-88.1683 Almashal et al. / European Journal of Chemistry 9 (2) (2018) 84-88 87 Table 1. The Mulliken atomic charge distribution of compounds T1-T9. Atoms Mulliken atomic charges (Q/e) Compounds T1 T2 T3 T4 T5 T6 T7 T8 T9 1 C 0.0186 0.0186 0.0162 0.0149 0.0163 0.0174 0.0162 0.0153 0.0170 2 C 0.0189 0.0189 0.0162 0.0161 0.0167 0.0183 0.0165 0.0160 0.0174 3 C 0.4011 0.4011 0.4003 0.4004 0.4004 0.4012 0.4003 0.4004 0.4006 4 N -0.5172 -0.5172 -0.5158 -0.5154 -0.5159 -0.5168 -0.5159 -0.5154 -0.5164 5 C 0.4003 0.4003 0.3996 0.3993 0.3995 0.3999 0.3997 0.3994 0.3998 6 O -0.3008 -0.3008 -0.3015 -0.3022 -0.3015 -0.3012 -0.3016 -0.3019 -0.3013 7 O -0.2973 -0.2973 -0.2972 -0.2967 -0.2970 -0.2972 -0.2969 -0.2970 -0.2969 8 C 0.1547 0.1547 0.1521 0.1517 0.1527 0.1543 0.1526 0.1516 0.1536 9 C 0.0941 0.0941 0.0904 0.0884 0.0909 0.0929 0.0904 0.0889 0.0917 10 C 0.0127 0.0127 0.0104 0.0088 0.0107 0.0120 0.0104 0.0092 0.0114 11 C -0.0760 -0.0760 -0.0775 -0.0780 -0.0772 -0.0763 -0.0776 -0.0778 -0.0769 12 C 0.0231 0.0231 0.0246 0.0249 0.0245 0.0238 0.0247 0.0248 0.0243 13 C 0.1719 0.1719 0.1701 0.1692 0.1703 0.1706 0.1703 0.1692 0.1706 14 C 0.1456 0.1456 0.1437 0.1409 0.1439 0.1453 0.1436 0.1419 0.1447 15 N -0.2059 -0.2059 -0.2079 -0.2096 -0.2077 -0.2071 -0.2081 -0.2088 -0.2078 16 N -0.2045 -0.2045 -0.2043 -0.2038 -0.2043 -0.2046 -0.2039 -0.2038 -0.2042 17 C 0.0506 0.0506 0.0491 0.0450 0.0493 0.0495 0.0487 0.0454 0.0481 18 C 0.0770 0.0770 0.0581 0.0650 0.0624 0.0755 0.0622 0.0660 0.0741 19 C 0.1167 0.1167 0.1074 0.1071 0.1086 0.1116 0.1078 0.1079 0.1141 20 C 0.1074 0.1074 0.1130 0.0905 0.1132 0.1343 0.1119 0.0987 0.1047 21 C -0.3940 -0.3940 -0.3169 -0.2934 -0.3201 -0.3003 -0.3192 -0.3004 -0.3232 22 C 0.1402 0.1402 0.1570 0.1301 0.1564 0.0950 0.1581 0.1267 0.1239 23 S 1.1434 1.1434 1.1065 1.0763 1.1120 1.0879 1.1087 1.0816 1.1125 24 O -0.4609 -0.4609 -0.4703 -0.4777 -0.4674 -0.4880 -0.4681 -0.4739 -0.4961 25 O -0.4737 -0.4737 -0.5005 -0.5695 -0.4986 -0.4795 -0.5000 -0.5311 -0.4828 26 N -0.2928 -0.2928 -0.3133 -0.5415 -0.2958 -0.3140 -0.3055 -0.5182 -0.2932 Table 2. Calculated energies, dipole moment and frontier molecular orbital energies of compounds T1-T9 from the B3LYP/6-311+G(d,p) basis set calculations. Compounds HOMO (eV) LUMO (eV) ΔEH-L (eV) Dipole (Debye) E [B3LYP] (a.u.) T1 -0.2439 -0.1118 -0.1321 4.879 -1574.555 T2 -0.2513 -0.1163 -0.1350 9.484 -1727.239 T3 -0.2424 -0.1114 -0.1310 6.676 -1916.415 T4 -0.2374 -0.1088 -0.1286 6.057 -1723.427 T5 -0.2432 -0.1118 -0.1314 6.5614 -1837.749 T6 -0.2430 -0.1144 -0.1286 7.129 -1952.270 T7 -0.2429 -0.1112 -0.1317 6.440 -1877.082 T8 -0.2294 -0.1095 -0.1199 7.1553 -2142.466 T9 -0.2445 -0.1131 -0.1314 6.8231 -1821.703 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1 C 2 C 3 C 4 N 5 C 6 O 7 O 8 C 9 C 10 C 11 C 12 C 13 C 14 C 15 N 16 N 17 C 18 C 19 C 20 C 21 C 22 C 23 S 24 O 25 O 26 N C ha rg e (Q /e ) Atoms T1 T2 T3 T4 T5 T6 T7 T8 T9 Figure 2. Graphical reorientations of Mulliken charge distributions of compounds T1-T9. Furthermore, the orbital shapes (HOMO-LUMO) and the energy gap between the HOMO-LUMO which is a critical parameter to determine molecular electrical transport properties [27,28] were plotted in 3-dimensional (3D) by using at B3LYP/6-311+G(d,p) levels, respectively, are given in Figure 3. The values of the calculated energies, dipole moment and frontier molecular orbital energies of studied compounds (T1-T9) from the B3LYP/6-311+G(d,p) basis set calculations are given in Table 2. The lower value of dipole moment found 4.879 of compound T1 and highest value 9.484 of compound T2. The higher values for HOMO energy level was -0.2513 of compound T2, also the lower values for LUMO energy level was -0.1088 of compound T4. 2018 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.9.2.84-88.1683 88 Almashal et al. / European Journal of Chemistry 9 (2) (2018) 84-88 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0 1 2 3 4 5 6 7 8 9 10 En er gy (e V) Compounds HOMO (eV) LUMO (eV) Figure 3. Frontier molecular orbitals and the energy gap between the HOMO-LUMO of compounds T1-T9 by using at B3LYP/6-311+G(d,p) basis set calculations. 4. Conclusions Nine new heterocyclic azo compounds were prepared by coupling the diazonium salts with N-(4-methylpheneyl) maleimide and different sulfa compounds and characterized. Density function theory at B3LYP level calculation was performed. HOMO-LUMO energies of the studied compounds was calculated by the 6-311+G(d,p) higher basis set level. Mulliken charge distributions of the investigated compounds were also computed at same level of method. Acknowledgements The authors thank the Department of Chemistry at the College of Education for Pure Sciences, Basrah University for the support provided to conduct research in its laboratories. Disclosure statement Conflict of interests: The authors declare that they have no conflict of interest. Author contributions: All authors contributed equally to this work. Ethical approval: All ethical guidelines have been adhered. Sample availability: Samples of the compounds are available from the author. Funding University of Basrah http://dx.doi.org/10.13039/100012026 ORCID Faeza Almashal http://orcid.org/0000-0002-2398-663X Abeer Mohamed Jabar http://orcid.org/0000-0001-7649-7226 Adil Muala Dhumad http://orcid.org/0000-0003-4565-7500 References [1]. Heinrich, Z. Color Chemistry, Syntheses, properties and applications of organic dyes and pigments, VCH, 1991. [2]. Paraneswari, N.; Muthakrishnan, J.; Guanasekaran, P. Indian J Exp Biol. 2006, 44(8), 618-626. [3]. Brown, D.; Laboureur, P. Chemosphere 1983, 12(3), 405-414. [4]. Simu, G. M.; Dragomirescu, A.; Grad, M. E.; Savoiubalint, G.; Andoni, M.; Bals, G. Azo compounds with antimicrobial activity, 14th, Int. Electron. Conf. Syn. Org. Chem. ECSOC-14, 2010. [5]. Garg, H. G.; Prakash, C. J. Med. Chem. 1972, 15(4), 435-436. [6]. Browing, C. H.; Cohen, B.; Ellingworth, S; Gulbransen, R. J. 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Permissions for commercial use of this work beyond the scope of the License (http://www.eurjchem.com/index.php/eurjchem/pages/view/terms) are administered by Atlanta Publishing House LLC (European Journal of Chemistry). 2018 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.9.2.84-88.1683 http://dx.doi.org/10.13039/100012026 http://orcid.org/0000-0002-2398-663X http://orcid.org/0000-0001-7649-7226 http://orcid.org/0000-0003-4565-7500 http://www.eurjchem.com/index.php/eurjchem/pages/view/terms http://creativecommons.org/licenses/by-nc/4.0 http://www.eurjchem.com/index.php/eurjchem/pages/view/terms 1. Introduction 2. Experimental 2.1. Instrumentation 2.2. Synthesis 2.2.1. Preparation of N-(4-methylphenyl)maleimide (I) 2.2.2. General procedure for preparation of the heterocyclic azo compounds (T1-T9) 2.3. Computational details 3. Results and discussion 3.1. Synthesis and characterization 3.2. Computational results 3.2.1. Geometrical optimization 3.2.2. Mulliken population analysis 3.2.3. Total energies, dipole moments and molecular orbitals analysis 4. Conclusions Acknowledgements Disclosure statement Funding ORCID References PrintField10: PrintField11: PrintField12: PrintField13: PrintField14: PrintField20: PrintField21: PrintField22: PrintField23: PrintField24: