64
P.J. Coelho et al. / Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 59–65
Mp 123–125 ◦C. 1H NMR (DMSO-d6) ı 2,89 (s, 6H, 2×CH3), 6.15 (t,
1H, J = 2.8 Hz, 4ꢀ-H), 6.58 (dd, 1H, J = 4.8 and J = 1.2 Hz, 3ꢀ-H), 6.72
(d, 2H, J = 9.0 Hz, 3-H and 5-H), 6.93–6.95 (m, 1H, 5ꢀ-H), 7.12 (d,
2H, J = 9.0 Hz, 2-H and 6-H), 8.30 (s, 1H, CH N), 11.56 (br s, 1H,
NH). 13C NMR (DMSO-d6) ı 40.4, 109.4, 112.9, 114.8, 121.6, 122.8,
131.0, 141.0, 146.6, 148.6. IR (Nujol): 3462, 2726, 2669, 1619,
1558, 1515, 1223, 1164, 1125, 1083, 1093,1060, 1033 cm−1. MS
(EI) m/z (%) = 213 ([M]+, 100), 212 (77), 199 (11), 198 (24), 197 (19),
196 (41), 169 (14), 168 (11), 164 (11), 146 (11), 135 (13), 120 (16),
119 (11). HMRS: m/z (EI) for C13H15N3; calcd 213.1266; found:
213.1273.
lamp. The light from the UV lamp was filtered using a water filter
and then carried to the spectrophotometer holder perpendicu-
larly to the monitoring beam using an optical fibre system. The
light flux power, 40 W/m2, was measured with a Photometer with
UV-A probe. A temperature controlled (20 ◦C) 10 mm quartz cell
(3.5 mL) equipped with magnetic stirring was used. The maximum
absorption wavelength of the stable trans-isomer of the imines was
determined and then the absorbance was measured at ꢀmax while
performing UV–vis light irradiation/dark cycles.
Acknowledgments
2-((1H-pyrrol-2-yl)methyleneamino)phenol (6a) (reaction
time 5 h). Brown solid (78%). Mp 133–136 ◦C. 1H NMR (CDCl3) ı
6.35–6.37 (m, 1H, 4ꢀ-H), 6.83 (dd, 1H, J = 3.6 and J = 1.2 Hz, 3ꢀ-H),
6.90 (dt, 1H, J = 7.2 and J = 1.2 Hz, 4-H), 7.01 (dd, 1H, J = 7.8 and
J = 1.4 Hz, 3-H), 7.12–7.17 (m, 2H, 5ꢀ- and 5-H), 7.25 (dd, 1H, J = 7.8
and J = 1.4 Hz, 6-H), 8.44 (s, 1H, CH N), 9.53 (s, 1H, OH), 10.13 (br s,
1H, NH). 13C NMR (CDCl3) ı 111.7, 115.6, 116.6, 119.6, 120.4, 125.7,
128.1, 129.6, 146.9, 151.2, 179.3. IR (Nujol): 3337, 3274, 3116,
1928, 1692, 1623, 1596, 1586, 1533, 1300, 1282, 1247, 1215, 1173,
1247, 1173, 1118, 1090, 1028 cm−1. MS (EI) m/z (%) = 186 ([M]+,
38), 185 (34), 184 (100), 170 (21), 169 (72), 157 (14), 156 (13), 155
(15), 144 (39), 92 (12), 91 (15), 64 (17), 63 (23). HMRS: m/z (EI) for
Thanks are due to the Fundac¸ ão para a Ciência e Tecnolo-
gia (Portugal) and FEDER-COMPETE for financial support through
the research units Centro de Química - Universidade do Minho
and Centro de Química–Vila Real, Projects PTDC/QUI/66251/2006
(FCOMP-01-0124-FEDER-007429), PEst-C/QUI/UI0686/2011 (F-
COMP-01-0124-FEDER-022716) and a PhD grant to M. C. R. Castro
(SFRH/BD/78037/2011). The NMR spectrometer Bruker Avance III
400 is part of the National NMR Network and was purchased
within the framework of the National program for Scientific Re-
equipment, contract REDE/1517/RMN/2005 with funds from POCI
2010 (FEDER) and FCT.
C11H10N2O; calcd 186.0793; found: 186.0797.
2-((1H-pyrrol-2-yl)methyleneamino)-5-methylphenol (6b)
Appendix A. Supplementary data
(reaction time 4 h). Light brown solid (86%). Mp 165–167 ◦C. 1H
NMR (CDCl3) ı 2,32 (s, 3H, CH3) 6.33–6.35 (m, 1H, 4ꢀ-H), 6.71 (ddd,
1H, J = 8.0 Hz, J = 2.4 Hz and J = 0.8 Hz, 4-H), 6.77 (dd, 1H, J = 3.6 Hz
and J = 1.2 Hz, 3ꢀ-H), 6.83 (br d, 1H, J = 1.2 Hz, 6-H), 7.08–7.10 (m,
1H, 5ꢀ-H), 7.14 (d, 1H, J = 8.0 Hz, 3-H), 8.42 (s, 1H, CH N), 9.54 (s,
1H, OH), 10.34 (br s, 1H, NH). 13C NMR (CDCl3) ı 21.3, 111.3, 115.9,
116.0, 118.5, 121.0, 124.8, 123.0, 138.4, 146.0, 151.1, 179.4. IR
(Nujol): 3338, 3249, 3106, 1873, 1717, 1704, 1628, 1604, 1580,
Supplementary data associated with this article can be
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1555, 1500, 1288, 1264, 1243, 1200, 1179, 1154, 1119, 1090 cm−1
.
MS (EI) m/z (%) = 200 ([M]+, 30), 199 (24), 198 (93), 197 (43), 184
(13), 183 (100), 169 (16), 78 (11). HMRS: m/z (EI) for C12H12N2O;
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2-((1-Methyl-1H-pyrrol-2-yl)methyleneamino)-5-
methylphenol (6c) (reaction time 5 h). Brown solid (59%).
Mp 123–124 ◦C. 1H NMR (DMSO-d6) ı 2.27 (s, 3H, CH3), 3.96 (s, 3H,
NCH3) 6.13–6.15 (m, 1H, 4ꢀ-H), 6.59–6.63 (m, 1H, 4-H), 6.67 (br
d, 1H, J = 1.2 Hz, 6-H), 6.73 (dd, 1H, J = 4.0 Hz and J = 1.2 Hz, 3ꢀ-H),
6.98 (d, 1H, J = 8.0 Hz, 3ꢀꢀ-H), 7.02 (t, 1H, J = 2.4 Hz, 5ꢀ-H), 8.44 (s, 1H,
CH N), 9.51 (s, 1H, OH). 13C NMR (DMSO-d6) ı 20.7, 36.1, 108.4,
116.1, 117.4, 118.1, 120.1, 129.1, 130.3, 135.6, 136.5, 149.2, 179.5.
IR (Nujol): 3111, 2727, 1864, 1741, 1694, 1603, 1570, 1528, 1341,
1315, 1296, 1268, 1245, 1194, 1158, 1114, 1093, 1057 1012 cm−1
.
MS (EI) m/z (%) = 213 ([M−H]+, 12), (12), 212 (62), 211 (100). HMRS:
m/z (EI) for C13H13N2O; calcd 213.1028; found: 213.1026.
1-((1H-pyrrol-2-yl)methyleneamino)naphthalen-2-ol
(7)
(reaction time 24 h). Green solid (102 mg, 59%). Mp 230–232 ◦C.
1H NMR (DMSO-d6) 6.56 (t, 1H, J = 2.0 Hz, 4ꢀ-H), 6.96 (br d, 1H,
J = 8.8 Hz, naphthyl-H), 7.06 (br d, 1H, J = 8.8 Hz, 1H, naphthyl-
H),7.22–7.25 (m, 1H, 3ꢀ-H), 7.40 (br t, 1H, J = 7.6 Hz, naphthyl-H),
7.51–7.60 (m, 2H, 5ꢀ-H and naphthyl-H), 7.66 (br s, 1H, naphthyl-
H), 7.95 (br d, 1H, J = 8.4 Hz, naphthyl-H), 8.13 (s, 1H, CH N), 13.5
(br s, 2H, NH and OH). IR (Nujol): 2726, 1656, 1631, 1513, 1603,
1322, 1285, 1268, 1254, 1211, 1114, 1089, 1077, 1045, 1000 cm−1
.
MS (EI) m/z (%) = 236 ([M]+, 16), 235 (16), 234 (100), 219 (22), 206
(16), 205 (28), 194 (30), 178 (12), 114 (18), 113 (11). HMRS: m/z
(ESI) for C15H12N2O; calcd 236.0950; found: 236.0948.
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4.4. Photochromic measurements
UV irradiation experiments were made using a UV–vis Cary
50 Varian spectrometer coupled to a 150 W ozone free Xenon