372
Q. Liu et al. / Dyes and Pigments 91 (2011) 370e377
in EtOH for 2e3 h. The details of reaction conditions and yields are
provided in Table 1.
13.49; Found: C, 65.00; H, 5.50; N, 12.79. UVeVis (MeOH) lmax:
378 nm.
3
: 2.76 ꢂ 104 L molꢀ1 cmꢀ1
.
2.3.5. 5-[(5-Methoxy-1H-Indol-3-yl)methylene]-2-(1-piperidinyl)
2.3. Structural confirmation
rhodanine(5b)
Yellow rod-like crystal, m.p.: 289e290 ꢁC. 1H NMR (DMSO-d6,
2.3.1. 5-(3-Methyl-2-benzothiazolinylidene)rhodanine (1a)
Yellow powder, m.p.: 254e255 ꢁC. 1H NMR (DMSO-d6,
400 MHz) d(ppm): 11.87 (s, 1H, NH), 7.88 (s, 1H, pyrrole-H), 7.68
(d, J ¼ 2.8 Hz, ArH), 7.33e7.37 (m, 1H, ArH), 7.35 (s, 1H, eCH]),
400 MHz)
7.60 (d, J ¼ 8.4 Hz, 1H, ArH), 7.46e7.50(m, 1H, ArH), 7.29e7.33(m,
1H, ArH), 3.90 (s, 3H, NCH3); IR (KBr) : 3446 (m. b, yNeH), 3086
(s, ]CeH), 2928, 2834 (m, yCeH), 1622 (s, yC]C yC]O), 1492, 1304
(m, dNeH yCeN), 1442 (m, dCeH), 1254 (s, yC]S), 741 (w,
]CeH)cmꢀ1
d(ppm): 13.25 (s, 1H, NH), 7.88 (d, J ¼ 8.4 Hz, 1H, ArH),
6.81e6.85 (m, 1H, ArH), 3.88 (b, 2H, NCH2), 3.82 (s, 3H,eOCH3), 3.61
(b, 2H, NCH2), 1.68 (b, 4H, 2eCH2e), 1.62 (b, 2H, eCH2e); IR(KBr)
3445 (m. b, yNeH), 3093 (s, ]CH), 2939, 2855 (m, yCeH), 1663
(m, yC]C), 1602(s, yC]O), 1548 (s, yC]N), 1442, 1383 (m, dCeH), 1263
(s, yCeOeC), 1062 (w, yCeOeC), 915, 877 (w,
]CH), 709 (m, dNeH)cmꢀ1
y:
y
y
y
,
,
d
.
d
.
MS (70 eV) m/z (%): 280 (51), 221 (12), 192 (100), 178 (12), 102 (26),
69 (8), 45 (8), 32 (3). Anal. Calcd. for C11H8N2OS3 ¼ 279.98: C, 47.12;
H, 2.88; N, 9.99; Found: C, 47.06; H, 2.48; N, 9.85. UVeVis (MeOH)
MS (70 eV) m/z (%): 341 (38), 231 (2), 203 (100), 188 (11), 169 (7),
147 (5), 97 (6), 44 (13). Anal. Calcd. for C18H19N3O2S ¼ 341.12: C,
63.32; H, 5.61;N, 12.31; Found: C, 63.08; H, 5.32; N, 12.26. UVeVis
lmax: 426 nm.
3
: 1.69 ꢂ 104 L molꢀ1 cmꢀ1
.
(MeOH) lmax: 380 nm.
3
: 2.96 ꢂ 104 L molꢀ1 cmꢀ1
.
2.3.2. 5-(1-Methyl-2-quinolylidene)rhodanine (2a)
Brownish yellow power, m.p.: 248e249 ꢁC. 1H NMR (DMSO-d6,
2.3.6. 5-[(5-Benzyloxy-1H-Indol-3-yl)methylene]-2-(1-piperidinyl)
rhodanine (5c)
400 MHz)
7.76 (d, J ¼ 8.4 Hz, 1H, eCH]), 7.71e7.73 (m, 2H, ArH), 7.41e7.44
(m, 2H, ArH), 3.97 (s, 3H, NCH3); IR (KBr) : 3445 (m. b, yNeH), 3100
(m, ]CeH), 2968, 2849 (m, yCeH), 1639 (m, yC]C), 1598 (s, yC]O),
1558, 1313 (m, dNeH
d(ppm): 12.85 (s, 1H, NH), 7.88 (d, J ¼ 8.4 Hz, 1H, eCH]),
Yellow needle-like crystal, m.p.: >300 ꢁC. 1H NMR (DMSO-d6,
400 MHz) d(ppm): 11.87 (s, 1H, NH), 7.88 (s, 1H, pyrrole-H), 7.69
y
(s, 1H, ArH), 7.40e7.43 (m, 6H, ArH, eCH]), 7.34 (d, J ¼ 6.8 Hz,
1H, eCH]), 6.93 (d, J ¼ 6.8 Hz,1H, ArH), 5.19 (s, 2H, eOCH2Ph), 3.89
(b, 2H, NCH2), 3.62 (b, 2H, NCH2), 1.69 (b, 4H, 2eCH2e), 1.63
y
,
yCeN), 1439 (m, dCeH), 1221 (s, yC]S), 743 (w, d]
CeH) cmꢀ1. MS (70 eV) m/z (%): 274 (34), 215 (10), 186 (100), 172 (2),
116 (9), 93 (16), 77 (5), 69 (4), 59 (4), 45 (13). Anal. Calcd. for
C13H10N2OS2 ¼ 274.02: C, 56.91; H, 3.67; N, 10.91. Found: C, 56.37;
(b, 2H, eCH2e); IR (KBr) y: 3454 (m. b, yNeH), 3097 (m, y]CH), 2921,
2853 (m, yCeH), 1650 (m, yC]C), 1595 (s, yC]O), 1542 (s, yC]N), 1443,
1375 (m, dCeH), 1262 (s, yCeOeC), 1056 (w, yCeOeC), 901, 836 (m, d]
CeH), 746 (m, dNeH) cmꢀ1; MS (70 eV) m/z (%): 417 (12), 334 (90),
206 (30), 169 (100), 147 (72), 119 (28), 77 (30), 69 (66), 44 (83). Anal.
Calcd. for C24H23N3O2S ¼ 417.15: C, 69.04; H, 5.55;N, 10.06; Found:
H, 3.19; N, 10.97. UVeVis (MeOH) lmax: 478 nm.
3
: 1.21 ꢂ104 L
molꢀ1 cmꢀ1
.
2.3.3. 5-(1-Methyl-2- pyridinylidene)rhodanine (3a)
Brown massive solid, m.p.: >300 ꢁC. 1H NMR(DMSO-d6,
400 MHz)
(ppm): 12.55 (s, 1H, NH), 8.56 (d, J ¼ 8.8 Hz, 1H, ArH),
7.99 (d, J ¼ 8.8 Hz, 1H, ArH), 7.60e7.64 (m, 1H, ArH), 6.81e6.84 (m,
1H, ArH), 3.97 (s, 3H, NCH3); IR(KBr) : 3445 (m. b, yNeH), 3057(m,
]CeH), 2979, 2851 (m, yCeH), 1679 (m, yC]C), 1639 (s, yC]O), 1565,
C, 68.64; H, 5.39; N, 9.31.UVeVis (MeOH) lmax: 397 nm.
3:
2.17 ꢂ 104 L molꢀ1 cmꢀ1
.
d
2.4. Crystal data
y
y
yCeN),1430 (w, dCeH), 1238 (s, yC]S) cmꢀ1. MS (70 eV)
Crystals suitable for X-ray analysis were obtained by slow
evaporation of a solution of the dyes in ethanol. All the measure-
ments were made on a Bruker SMART APEX II CCD X-ray crystal-
1330 (m, dNeH
,
m/z (%): 224 (20), 165 (100), 137 (2), 122 (4), 95 (7), 77 (17), 69 (55),
55 (41). Anal. Calcd. for C9H8N2OS2 ¼ 224.01: C, 48.19; H, 3.59; N,
lography equipped with
a
graphite monochromated Mo
Ka
12.49; Found: C, 47.73; H, 3.81; N, 12.68. UVeVis (MeOH) lmax
:
: 1.53 ꢂ 104 L molꢀ1 cmꢀ1
.
radiation (
l
¼ 0.071073 nm) by using
u
scan technique at room
435 nm.
3
temperature. The structures were solved by direct methods with
SHELXL-97 [20], and refined using the full-matrix least-squares
procedures on F2 with anisotropic thermal parameters for all non-
hydrogen atoms using SHELXL-97 [21]. Hydrogen atoms were
generated geometrically. Figs. 1 and 2 show the molecular struc-
tures with numbering systems of dye 5a and 5b, respectively. The
crystal data, details concerning data collection and structure
refinement for dye 5a and 5b are summarized in Table 2.
2.3.4. 5-[(1H-Indol-3-yl)methylene]-2-(1-piperidinyl)
rhodanine (5a)
Yellow granular crystal, m.p.: 245e246 ꢁC. 1H NMR (DMSO-d6,
400 MHz) d(ppm): 12.01 (s, 1H, NH), 7.87 (s, 1H, pyrrole-H), 7.84
(d, J ¼ 8.0 Hz, 1H, ArH), 7.75 (s, 1H, eCH]), 7.48 (d, J ¼ 8.0 Hz, 1H,
ArH), 7.16e7.25 (m, 2H, ArH), 3.89 (b, 2H, NCH2), 3.62 (b, 2H, NCH2),
1.69 (b, 4H, 2eCH2e), 1.63 (b, 2H, eCH2e); IR(KBr)
yNeH), 3089 (m, ]CH), 2928, 2854 (m, yCeH), 1659 (m, yC]C), 1602(s,
dNeH
y: 3424 (m. b,
y
3. Results and discussion
yC]O), 1543 (s, yC]N), 1443, 1383 (m, dCeH), 744 (s, d]CeH
,
)
cmꢀ1. MS (70 eV) m/z (%): 311 (52), 201 (3), 173 (100), 146 (5), 129
(13), 41 (3). Anal. Calcd. for C17H17N3OS ¼ 311.11:C, 65.57; H, 5.50; N,
3.1. Synthesis
In all cases investigated, we found that the rhodanine mer-
ocyanine dye formation reactions proceeded efficiently with high to
excellent yields in short reaction times. A series of rhodanine mer-
ocyanine dyes were successfully synthesized with high yields
66e86% within 2e3 min by using microwave method. The products
were purified by recrystallized from ethanol or acetone. In order to
get effective results, we examined the difference between two
different methods (Table 1). There was no doubt that microwave
method was more effective and novel, for its high yields, shorter
reaction times and environmental protection. From irradiation
power it could be found that the sequence of the reaction activity for
Table 1
The reaction conditions and yields for the dyes.
Dye
Solvent method
Microwave method
Time/h
Yield/%
Power/W
Time/min
Yield/%
1a
2a
3a
5a
5b
5c
2e3
2e3
2e3
2e3
2e3
2e3
57
53
64
83
80
76
567
406
406
252
252
252
3
2
3
3
3
3
66
69
68
86
83
81