Paper
NJC
4
4J = 1.6 Hz), 8.28 (d, 3J = 8.0 Hz), 8.40 (d, J = 1.6 Hz); 13C-NMR 0.12 g (27.5%); orange solid; mp: 79 1C; 1H-NMR (500 MHz,
3
(125 MHz, CDCl3): 87.3, 89.4, 121.4, 125.3, 125.8, 127.4, 128.2, CDCl3): 4.01 (s), 4.09 (s), 7.34 (m), 7.52 (t, J = 4.0 Hz, 3J = 3.0 Hz),
129.0, 129.8, 130.3, 132.1, 133.5, 136.3, 181.9; IR (KBr) 7.54 (t, 3J = 3.6 Hz), 7.62 (m), 7.81 (dd, 3J = 7.0 Hz, 4J = 1.0 Hz), 8.26
3202, 2205, 1663, 1572, 898, 786; LCMS for C26H12O2S2 cal. (m), 8.30 (dd, 3J = 7.05 Hz, 4J = 1.0 Hz), 8.32 (m); 13C-NMR (125 MHz,
420.03 g molÀ1, found 420 [M]+.
CDCl3): 63.9, 64.3, 87.1, 91.1, 116.4, 122.3, 123.3, 124.6, 124.9, 125.3,
126.1, 126.2, 128.1, 129.9, 132.8, 148.6, 148.9; IR (KBr) 3104, 3060,
2999, 2939, 2838, 2350, 1619, 1609, 1062, 808, 758, 625; GC-MS for
C22H16O2S cal. 344.09 g molÀ1, found 345 [M]+.
1-(Thiophene-3-ylethynyl)-9,10-anthraquinone (4). 1-Bromo-
9,10-anthraquinone (14) (1.0 g, 3.5 mmol) was used to yield
0.77 g (70%); brown solid; mp: 143 1C; 1H-NMR (500 MHz,
CDCl3): 7.14 (m), 7.25 (m), 7.56 (m), 7.76 (dd, 3J = 5.8 Hz, 4J = 3.3 Hz),
8.28 (dd, 3J = 7.6 Hz, 4J = 3.4 Hz); 13C-NMR (125 MHz, CDCl3): 73.5,
76.5, 120.9, 125.6, 126.3, 126.7, 127.2, 127.4, 128.5, 130.1, 131.2,
132.0, 133.4, 133.5, 133.7, 134.1, 137.3, 138.9, 181.7, 181.8; IR (KBr)
3101, 2914, 2847, 2138, 1670, 783; GC-MS for C20H10O2S cal.
314.04 g molÀ1, found 315 [M]+.
2-(Thiophene-3-ylethynyl)-9,10-dimethoxyanthracene (10). 2-Bromo-
9,10-dimethoxyanthracene (20) (0.4 g, 1.26 mmol) was used to yield
0.15 g (34.7%); brown solid; mp: 141 1C; 1H-NMR (500 MHz, CDCl3):
4.01 (s), 4.05 (s), 7.27 (t, 3J = 7.27 Hz), 7.34 (t, 3J = 7.34 Hz), 7.50 (m),
7.61 (dd, 3J = 7.61 Hz, 4J = 1.0 Hz), 7.81 (m), 7.88 (m), 8.25 (m), 8.41
(s); 13C-NMR (125 MHz, CDCl3): 63.2, 64.0, 87.2, 91.1, 117.9, 122.4,
123.1, 123.2, 124.4, 125.4, 125.8, 127.2, 128.2, 129.9, 133.5, 134.1,
148.4, 149.1; IR (KBr) 3104, 3066, 2936, 2844, 2208, 1673, 1065, 872,
827, 786, 726, 625; GC-MS for C22H16O2S cal. 344.09 g molÀ1, found
345 [M]+.
2-(Thiophene-3-ylethynyl)-9,10-anthraquinone (5). 2-Bromo-
9,10-anthraquinone (15) (1.0 g, 3.5 mmol) was used to yield
0.88 g (80%); orange solid; mp: 168 1C; 1H-NMR (500 MHz,
3
CDCl3): 7.23 (d, J = 4.8 Hz), 7.34 (m), 7.61 (m), 7.78 (m), 7.82
(m), 8.25 (m), 8.35 (m); 13C-NMR (125 MHz, CDCl3): 87.7, 89.5,
121.3, 125.7, 127.2, 127.3, 129.5, 129.8, 130.0, 132.1, 133.3,
133.4, 133.5, 134.1, 136.2, 182.4, 182.5; IR (KBr) 3098, 3066,
2961, 2923, 2208, 1679, 1587, 875, 787, 745; GC-MS for
Crystallography
Crystals suitable for single-crystal X-ray diffraction studies were
obtained by slow evaporation of solution of 5 (acetone) and 19
(toluene). Information concerning the crystallographic data
and the structure refinement calculations of the three
compounds is summarized in Table 2. The intensity data were
collected on a Kappa/APEX II (Bruker AXS) diffractometer, with
Mo Ka radiation (l = 7.1073 nm) using o and j scans.
Reflections were corrected for background, Lorentz, and polar-
ization effects. Preliminary structure models were derived by
application of direct methods37 and were refined by full-matrix
least squares calculations on the basis of F2 for all reflections.38
The hydrogen atoms were included in the models in the
calculated positions and were refined as constrained to
bonding atoms.
C
20H10O2S cal. 314.04 g molÀ1, found 315 [M]+.
1,4-Bis(thiophene-3-ylethynyl)-9,10-dimethoxyanthracene (6).
1,4-Dibromo-9,10-dimethoxyanthracene (16) (0.5 g, 1.26 mmol)
was used to yield 0.16 g (28%); yellow solid; mp: 98.2 1C;
3
1H-NMR (500 MHz, CDCl3): 4.01 (s), 7.06 (d, J = 5.0 Hz), 7.15
(m), 7.39 (m), 7.40 (s), 7.48 (m), 8.19 (dd, 3J = 7.5 Hz, 4J = 1.0 Hz);
13C-NMR (125 MHz, CDCl3): 63.1, 73.6, 76.6, 120.9, 122.6, 124.9,
125.3, 125.6, 127.2, 130.1, 131.2, 133.5, 134.1, 148.4; IR (KBr)
3104, 2993, 2936, 2838, 2208, 1676, 1068, 818, 780, 622; LCMS
for C28H18O2S2 cal. 450.07 g molÀ1, found 449.2 [M]+.
1,5-Bis(thiophene-3-ylethynyl)-9,10-dimethoxyanthracene (7).
1,5-Dibromo-9,10-dimethoxyanthracene (17) (0.5 g, 1.26 mmol) Electronic structure calculations
was used to yield 0.24 g (42%); yellow solid; mp: 104.8 1C;
The DFT calculations on individual, free molecules were carried
3
1H-NMR (500 MHz, CDCl3): 4.14 (s), 7.28 (t, J = 7.2 Hz), 7.33
out by using the Naval Research Laboratory Molecular Orbital
Library (NRLMOL) program,39–45 which is an all-electron imple-
mentation of DFT. NRLMOL combines large Gaussian orbital
basis sets, numerically precise variational integration and an
analytic solution of Poisson’s equation in order to accurately
determine the self-consistent potentials, secular matrix, total
energies, and Hellmann–Feynman–Pulay forces.46 The GGA/
PBE47 functional was used to describe the exchange–correlation
effects of the electrons. Because no structure data were available
(except for compound 5), we generated starting geometries by
AVOGADRO,48,49 and geometry optimization was performed
using the NRLMOL package. All results are based on these
geometries. The transport calculations are based on the
non-equilibrium Greens-functions (NEGF) approach as imple-
mented in QuantumWise.50–52 QuantumWise is a commercial
implementation of the TranSIESTA-code. It allows one to calcu-
3
4
(m), 7.54 (dd, J = 7.5 Hz, J = 1.4 Hz), 7.61 (m), 8.32 (m), 8.44
(dd, J = 8.0 Hz, J = 0.6 Hz); 13C-NMR (125 MHz, CDCl3): 63.6,
85.9, 89.7, 120.4, 122.7, 123.5, 124.8, 125.5, 127.4, 129.0, 130.1,
133.3, 148.4; IR (KBr) 3107, 2920, 2847, 2208, 1676, 1059, 783,
622; LCMS for C28H18O2S2 cal. 450.07 g molÀ1, found 449.3 [M]+.
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4
2,6-Bis(thiophene-3-ylethynyl)-9,10-dimethoxyanthracene (8).
2,6-Dibromo-9,10-dimethoxyanthracene (18) (0.5 g, 1.26 mmol)
was used to yield 0.27 g (47%); yellow solid; mp: 127.2 1C;
1H-NMR (500 MHz, CDCl3): 4.00 (s), 7.24 (dd, 3J = 7.41 Hz,
4J = 1.0 Hz), 7.51 (m), 8.10 (m), 8.36 (m), 8.49 (d, J = 2.8 Hz);
4
13C-NMR (125 MHz, CDCl3): 54.3, 85.3, 88.3, 101.9, 120.8, 121.9,
122.8, 123.7, 125.8, 129.0, 129.6, 129.8, 130.7, 138.4; IR (KBr)
3101, 2987, 2933, 2838, 2208, 1673, 1071, 872, 827, 818, 625;
LCMS for C28H18O2S2 cal. 450.07 g molÀ1, found 453.3 [M]À.
1-(Thiophene-3-ylethynyl)-9,10-dimethoxyanthracene (9). 1-Bromo- late exactly the electronic properties of molecular junctions by
9,10-dimethoxyanthracene (19) (0.4 g, 1.26 mmol) was used to yield using a localised basis set combined with the pseudopotential
c
608 New J. Chem., 2013, 37, 601--610
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013