8038 J. Am. Chem. Soc., Vol. 123, No. 33, 2001
Dudek et al.
stored because thioacetate-protected oligomers are more stable than their
corresponding thiols. As needed to form self-assembled monolayers,
the thioacetates are deprotected in small quantities with LiAlH4 as
described in the Supporting Information and deposited onto gold
substrates immediately.
4-((E)-2-Ferrocenylvinyl)benzyl thioacetate (thioacetate of 1a):
1H NMR (400 MHz, CDCl3, ppm) δ 2.36 (s, SCOCH3, 3 H), 4.11 (s,
benzyl, 2 H), 4.13 (s, Fc, 5 H), 4.28 (d, Fc, J ) 1.68 Hz, 2 H), 4.45 (d,
Fc, J ) 1.68 Hz, 2 H), 6.67 (d, vinyl, J ) 16.0 Hz, 1 H), 6.86 (d,
vinyl, J ) 16.1 Hz, 1 H), 7.25 (d, aromatic, J ) 8.5 Hz, 2 H), 7.37 (d,
aromatic, J ) 8.1 Hz, 2 H); ES-MS m/e 376. Anal. Calcd for C21H20-
OFeS: C, 66.85; H, 5.61. Found: C, 67.08; H, 5.53.
4-((E)-2-Ferrocenylvinyl)-3,5-diethoxybenzyl thioacetate (thio-
acetate of 1b): 1H NMR (400 MHz, CDCl3, ppm) δ 1.48 (t, OCH2CH3,
J ) 6.8 Hz, 6 H), 2.35 (s, SCOCH3, 3 H), 4.05 (s, benzyl, 2 H), 4.07
(q, OCH2CH3, J ) 6.8 Hz, 4 H), 4.12 (s, Fc, 5 H), 4.23 (t, Fc, J ) 1.8
Hz, 2 H), 4.44 (t, Fc, J ) 1.8 Hz, 2 H), 6.47 (s, aromatic, 2 H), 6.99
(d, vinyl, J ) 16.5 Hz, 1 H), 7.29 (d, vinyl, J ) 16.5 Hz, 1 H); ES-MS
m/e 464. Anal. Calcd for C25H28O3FeS: C, 64.66; H, 6.08. Found: C,
64.89; H, 6.02.
4-[(E)-2-(4-((E)-2-[4-((E)-2-(4-((E)-2-Ferrocenylvinyl)phenyl)-
vinyl]-3,5-diethoxyphenyl)vinyl)phenyl)vinyl]-3,5-diethoxybenzyl thio-
1
acetate (thioacetate of 4): H NMR (400 MHz, CDCl3, ppm) δ 1.51
(t, OCH2CH3, J ) 7.0 Hz, 6 H), 1.55 (t, OCH2CH3, J ) 7.0 Hz, 6 H),
2.37 (s, SCOCH3, 3 H), 4.08 (s, benzyl, 2 H), 4.11 (q, OCH2CH3, J )
7.0 Hz, 4 H), 4.15 (s, Fc, 5 H), 4.20 (q, OCH2CH3, J ) 7.0 Hz, 4 H),
4.29 (s, Fc, 2 H), 4.48 (s, Fc, 2 H), 6.50 (s, aromatic, 2 H), 6.70 (d,
vinyl, J ) 16.2 Hz, 1 H), 6.73 (s, aromatic, 2 H), 6.88 (d, vinyl, J )
16.0 Hz, 1 H), 7.06 (d, vinyl, J ) 16.2 Hz, 1 H), 7.08 (d, vinyl, J )
16.2 Hz, 1 H), 7.41 (d, aromatic, J ) 8.2 Hz, 2 H), 7.50 (m, vinyl and
aromatic, 7 H), 7.56 (d, vinyl, J ) 16.5 Hz, 1 H), 7.68 (d, vinyl, J )
16.7 Hz, 1 H), 7.73 (d, vinyl, J ) 16.5 Hz, 1 H); MALDI-MS m/e
859. Anal. Calcd for C53H54O5SFe: C, 74.12; H, 6.34. Found: C, 73.91;
H, 6.50.
4-((E)-2-[4-((E)-2-[4-((E)-2-[4-((E)-2-[4-((E)-2-Ferrocenylvinyl)-
3,5-diethoxyphenyl]vinyl)phenyl]vinyl)-3,5-diethoxyphenyl]vinyl)-
phenyl]vinyl)-3,5-diethoxybenzyl thioacetate (thioacetate of 5): 1H
NMR (400 MHz, CDCl3, ppm) δ 1.51 (t, OCH2CH3, J ) 6.9 Hz, 6 H),
1.54 (t, OCH2CH3, J ) 7.1 Hz, 6 H), 1.56 (t, OCH2CH3, J ) 7.0 Hz,
6 H), 2.37 (s, SCOCH3, 3 H), 4.08 (s, benzyl, 2 H), 4.11 (q, OCH2-
CH3, J ) 7.0 Hz, 4 H), 4.15 (s, fc, 5 H), 4.18 (q, OCH2CH3, J ) 6.9
Hz, 4 H), 4.20 (q, OCH2CH3, J ) 7.0 Hz, 4 H), 4.26 (s, fc, 2 H), 4.48
(s, fc, 2 H), 6.50 (s, vinyl, 2H), 6.73 (s, aromatic, 2 H), 6.74 (s, aromatic,
2 H), 7.06 (m, aromatic & vinyl, 5 H), 7.45 (d, vinyl, J ) 16.3 Hz, 1
H), 7.51 (m, aromatic and vinyl, 9 H), 7.58 (d, vinyl, J ) 16.7 Hz, 1
H), 7.68 (d, vinyl, J ) 16.6 Hz, 1 H), 7.75 (d, vinyl, J ) 16.5 Hz,
1H); MALDI-MS m/e 1047. Anal. Calcd for C65H68O7SFe: C, 74.41;
H, 6.53. Found: C, 74.61; H, 6.43.
Monolayer Preparation.18 A 200-Å-thick adhesion layer of titanium
and a 2000-Å-thick layer of gold were evaporated on a clean silicon
wafer. After a 5-s dip in a “piranha” solution (1 volume of H2SO4/1
volume of 30% H2O2), the gold substrates were rinsed with water,
ethanol, and chloroform. The cleaned substrates were soaked in
chloroform solutions containing a total concentration of 0.3 mM thiol
composed of the desired ferrocene OPV thiol and the diluent thiol.
The samples were removed from the deposition solution after 2 h and
rinsed sequentially with chloroform, ethanol, water, ethanol, and
chloroform and dried under argon.
4-[(E)-2-(4-((E)-2-Ferrocenylvinyl)phenyl)vinyl]benzyl thioacetate
(thioacetate of 2a): 1H NMR (400 MHz, CDCl3, ppm) δ 2.36 (s,
SCOCH3, 3 H), 4.13 (s, benzyl, 2 H), 4.14 (s, Fc, 5 H), 4.30 (s, Fc, 2
H), 4.47 (s, Fc, 2 H), 6.69 (d, vinyl, J ) 16.2 Hz, 1 H), 6.89 (d, vinyl,
J ) 16.2 Hz, 1 H), 7.27 (d, aromatic, J ) 8.2 Hz, 2 H), 7.41 (d,
aromatic, J ) 8.2 Hz, 2 H), 7.45 (d, aromatic, J ) 7.9 Hz, 2 H), 7.47
(d, aromatic, J ) 7.9, 2 H); MALDI-MS m/e 478. Anal. Calcd for
C29H26OSFe: C, 72.80; H, 5.48. Found: C, 72.61; H, 5.36.
4-[(E)-2-(4-((E)-2-Ferrocenylvinyl)phenyl)vinyl]-3,5-diethoxy-
1
benzyl thioacetate (thioacetate of 2b): H NMR (400 MHz, CDCl3,
ppm) δ 1.50 (t, OCH2CH3, J ) 7.0 Hz, 6 H), 2.36 (s, SCOCH3, 3 H),
4.10 (q, OCH2CH3, J ) 7.0 Hz, 4 H), 4.11 (s, benzyl, 2 H), 4.14 (s,
Fc, 5 H), 4.28 (t, Fc, J ) 1.8 Hz, 2 H), 4.47 (t, Fc, J ) 1.8 Hz, 2 H),
6.49 (s, aromatic, 2 H), 6.69 (d, vinyl, J ) 16.2 Hz, 1 H), 6.86 (d,
vinyl, J ) 16.0 Hz, 1 H), 7.40 (d, aromatic, J ) 8.3 Hz, 2 H), 7.46 (d,
aromatic, J ) 7.9 Hz, 2 H), 7.48 (d, vinyl, J ) 16.8 Hz, 1 H), 7.65 (d,
vinyl, J ) 16.6, 1 H); ES-MS m/e 566. Anal. Calcd for C33H34O3FeS:
C, 69.96; H, 6.05. Found: C, 70.32; H, 5.85.
4-[(E)-2-(4-((E)-2-Ferrocenylvinyl)-3,5-diethoxyphenyl)vinyl]-
1
benzyl thioacetate (thioacetate of 2c): H NMR (400 MHz, CDCl3,
Ellipsometry. Ellipsometry measurements were performed on a
ppm) δ 1.53 (t, OCH2CH3, J ) 7.0 Hz, 6 H), 2.37 (s, SCOCH3, 3 H),
4.13 (s, benzyl, 2 H), 4.15 (s, Fc, 5 H), 4.17 (q, OCH2CH3, J ) 7.0
Hz, 4 H), 4.26 (t, Fc, J ) 1.8 Hz, 2 H), 4.47 (t, Fc, J ) 1.7 Hz, 2 H),
6.70 (s, aromatic, 2 H), 7.02 (s, vinyl, 1 H), 7.03 (s, vinyl, 1 H), 7.06
(d, vinyl, J ) 16.2 Hz, 1 H), 7.28 (d, aromatic, J ) 8.1 Hz, 2 H), 7.37
(d, vinyl, J ) 16.5 Hz, 1 H), 7.45 (d, aromatic, J ) 8.2 Hz, 2 H);
MALDI-MS m/e 566. Anal. Calcd for C33H34O3SFe: C, 69.96; H, 6.05.
Found: C, 69.81; H, 6.03.
Gaertner Auto-Gain L116B ellipsometer.
Electrochemical Measurements.18 Electrochemical measurements
were made in a cell in which a bored-out cone of poly(tetrafluor-
ethylene) was pressed down against the sample. The electrolyte (1 M
HClO4), the counter electrode (platinum wire), and the reference
electrode (Ag/AgClO4) were then placed in the bore. A PAR 273
potentiostat, interfaced to a personal computer and modified to provide
smooth potential ramps, was used to record cyclic voltammograms and
perform chronoamperometry.
4-[(E)-2-(4-((E)-2-[4-((E)-2-Ferrocenylvinyl)-3,5-diethoxyphenyl]-
1
vinyl)phenyl)vinyl]benzyl thioacetate (thioacetate of 3a): H NMR
(400 MHz, CDCl3, ppm) δ 1.54 (t, OCH2CH3, J ) 7.1 Hz, 6 H), 2.37
(s, SCOCH3, 3 H), 4.13 (s, benzyl, 2 H), 4.15 (q, OCH2CH3, J ) 7.0
Hz, 4 H), 4.16 (s, Fc, 5 H), 4.27 (s, Fc, 2 H), 4.48 (s, Fc, 2 H), 6.72
(s, aromatic, 2 H), 7.06 (s, vinyl, 2 H), 7.07 (d, vinyl, J ) 17.2 Hz, 1
H), 7.09 (s, vinyl, 2 H), 7.29 (d, aromatic, J ) 8.0 Hz, 2 H), 7.38 (d,
vinyl, J ) 16.5 Hz, 1 H), 7.45 (d, aromatic, J ) 8.2 Hz), 7.51 (s,
aromatic, 4 H); ES-MS m/e 668. Anal. Calcd for C41H40O3SFe: C,
73.65; H, 6.03. Found: C, 73.43; H, 5.91.
Acknowledgment. We acknowledge valuable discussions
with John Smalley, Steve Feldberg, and Marshall Newton of
Brookhaven National Laboratory. This work was supported by
the National Science Foundation and the Office of Technology
Licensing at Stanford University. S.P.D. acknowledges sup-
port from a NIH Biotechnology Training Grant and H.D.S.
acknowledges support from a NSF Graduate Fellowship. S.P.D.
thanks Dr. Gerald Dudek at the Mass Spectrometry Facility,
Department of Chemistry, Harvard University, for mass spec-
trometric analyses.
4-[(E)-2-(4-((E)-2-[4-((E)-2-Ferrocenylvinyl)-3,5-diethoxyphenyl]-
vinyl)phenyl)vinyl]-3,5-diethoxybenzyl thioacetate (thioacetate of
1
3b): H NMR (400 MHz, CDCl3, ppm) δ 1.51 (t, OCH2CH3, J ) 7.0
Hz, 6 H), 1.54 (t, OCH2CH3, J ) 7.0 Hz, 6 H), 2.37 (s, SCOCH3, 3
H), 4.08 (s, benzyl, 2 H), 4.11 (q, OCH2CH3, J ) 7.0 Hz, 4 H), 4.15
(s, Fc, 5 H), 4.17 (q, OCH2CH3, J ) 7.0 Hz, 4 H), 4.26 (s, Fc, 2 H),
4.48 (s, Fc, 2 H), 6.50 (s, aromatic, 2 H), 6.72 (s, aromatic, 2 H), 7.06
(s, vinyl, 2 H), 7.07 (d, vinyl, J ) 16.6 Hz, 1 H), 7.38 (d, vinyl, J )
16.5 Hz, 1 H), 7.50 (s, aromatic, 4 H), 7.51 (d, vinyl, J ) 16.5 Hz, 1
H), 7.68 (d, vinyl, J ) 16.5 Hz, 1 H); MALDI-MS m/e 755. Anal.
Calcd for C45H48O5SFe: C, 71.42; H, 6.39. Found: C, 71.57; H, 6.41.
Supporting Information Available: Synthesis of ferrocene-
terminated OPV methyl thiols and their monomer components.
This material is available free of charge via the Internet at
JA0043340