Semiempirical AM1-TDHF calculations of the static first hyperpolarizabilities, β(0), of 1,3-thiazolium-5-thiolate mesoionic derivatives were performed. Guided by these results, two new mesoionic compounds - 2-(4-nitrophenyl)-3-methyl-4-(methylphenyl)-1,3-thiazolium-5-thiolate and 2-(4-nitrophenyl)-3-methyl-4-(methoxyphenyl)-1,3-thiazolium-5-thiolate - were synthesized and characterized by analytical and spectroscopic means.
The 13C NMR (APT, 50 MHz, DMSO-d6) study of the compound MIC-14 showed thirteen chemical shifts. Of these, seven were assigned to the quaternary carbons, two to the primary aliphatic carbons and four to the aromatic tertiary carbons. The carbons of the mesoionic ring of MIC-14 have chemical shifts in 152.1; 141.4 and 161.9 ppm assigned, respectively, to C2, C4 e C5 (see Figure 5a). The carbons C10 and C15 have chemical shifts of 40.6 and 21.4 ppm, while the aromatic carbons have chemical shifts of 132.7 (C6); 129.4 (C7, 7'); 123.8 (C8, 8'); 148.5(C9); 129.6 (C11); 129.8 (C12, 12'); 128.2 (C13, 13') and 139.1 (C14).
The 1H NMR (200 MHz, DMSO-d6) spectrum of MIC-14 shows six hydrogen signals. Of these, two intense singlets were observed in the aliphatic region with an integral of 6H for the hydrogens H10 and H15 of the methyl groups, respectively in 3.64 and 2.38 ppm. There was also a signal between 8.27 and 7.23 assigned to the eight aromatic hydrogens.
For compound MIC-16 we observed a similar chemical behavior. The 13C NMR (APT, 50 MHz, DMSO-d6) spectrum showed thirteen signals. The carbons of the mesoionic ring showed chemical shifts of 148.7; 142.5 and 162.5 for C2, C4 and C5, respectively (see Figure 5b). Carbons C10 and C15 show values of chemical shifts that are compatible with the N-methyl group in 40.8 and the methoxy group in 55.2. The aromatic carbons have chemical shifts of 132.6 (C6); 130.4 (C7, 7'); 124.6 (C8, 8'); 148.5 (C9); 121.3 (C11); 132.6 (C12, 12'); 114.3 (C13, 13') and 160.4 (C14).
The 1H NMR (200 MHz, DMSO-d6) spectrum of MIC-16 has six hydrogen signals. Of these, two intense singlets were observed in the aliphatic region with an integral of six hydrogens, three hydrogens were assigned to the N-methyl group of the heterocyclic ring in 3.69 ppm and three were assigned to the methoxy group in 3.90 ppm. In the region between 8.34 and 7.07 ppm we observed corresponding signals the eight aromatic hydrogens.
The results above are in agreement with the results observed by Athayde-Filho et al.14
0.19 g, (0.51 mmol); IR (KBr) ν max/cm-1: 3117, 3062, 2994, 1607, 1542, 1495, 1429, 1351, 1294; 1H NMR (300 MHz, CDCl3): δ 2.38 (s, 3H), 3.64 (s, 3H), 7.23 (d, J 8.2 Hz, 2H), 7.28 (d, J 8.2 Hz, 2H), 7.64 (d, J 8.8 Hz, 2H), 8.27 (d, J 8.8 Hz, 2H); 13C NMR (75 MHz, CDCl3): δ 161.9, 152.1, 141.4. 139.1, 148.5, 132.7, 129.8, 129.6, 129.4, 128.2, 123.8, 40.6, 21.4; MS (EI, 70 eV): m/z (%) = 343 [M+1] (17.74), 342 [M] (100), 327 (8.07), 296 (19.94), 281 (15.43), 179 (20.14), 166 (2.99), 135 (9.43), 119 (4.41), 91 (4.23), 75 (2.08); Anal. Calc. for C17H14N2O2S2: C, 59.63; H, 4.12; N, 8.18; S, 18.73. Found: C, 60.04; H, 4.71; N, 8.27; S, 19.03; yield 37%, mp 183-185 °C (recryst. EtOH:H2O (1:1, v/v)).
0.29 g, (0.78 mmol); IR (KBr) ν max/cm-1: 3009, 2967, 2897,1590, 1489, 1513, 1426, 1334, 1282; 1H NMR (300 MHz, CDCl3): δ 3.90 (s, 3H), 3.69 (s; 3H), 7.07 (d, J 8.8 Hz, 2H), 7.48 (d, J 8.8 Hz, 2H), 7.88 (d, J 8.4 Hz, 2H), 8.34 (d, J 8.4 Hz, 2H); 13C NMR (75 MHz, CDCl3): δ 162.5, 160.4, 148.7, 148.5, 142.5, 132.6, 130.4, 124.6, 121.3, 114.3, 55.2, 40.8; MS (EI, 70 eV): m/z (%) = 359 [M+1]+ (17), 358 [M] (94.62), 343 (9.58), 312 (47.77), 297 (32.37), 282 (11.51), 210 (9.95), 195 (100), 166 (6.64), 163 (18.62), 151 (29.44), 135 (40.27), 63 (17.59); Anal. Calc. for C17H14N2O3S2, C, 56.96; H, 3.94; N, 7.82; S 17.89. Found: C, 57.13; H, 3.87; N, 8.03; S, 18.03; 56%, mp 215-217 °C (recryst. EtOH:H2O (1:1, v/v)).
Print version ISSN 0103-5053
J. Braz. Chem. Soc. vol.21 no.5 São Paulo 2010
1,3-thiazolium-5-thiolates mesoionic compounds: semiempirical evaluation of their first static hyperpolarizabilities and synthesis of new examples
Bruno F. LyraI,II; Soraya A. de MoraisI; Gerd B. Rocha*,I; Joseph MillerII,III,; Gustavo L. C. MouraIII; Alfredo M. SimasIII; Clovis PeppeIV; Petrônio F. de Athayde-FilhoI,II
IDepartamento de Química, Universidade Federal da Paraíba, 58059-900 João Pessoa-PB, Brazil
IILaboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, CP 5009, 58051-970 João Pessoa-PB, Brazil
IIIDepartamento de Química Fundamental, Universidade Federal de Pernambuco, 50670-901 Recife-PE, Brazil
IVDepartamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria-RS, Brazil
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