A R T I C L E S
Sullivan et al.
mL). HCl (1 N, 0.5 mL) was then added. The reaction was allowed to
proceed for 2.5 h. The mixture was then neutralized with NaHCO3,
and the product was collected by filtration. The blue solid was obtained
The dendritic chromophores, relative to undressed chro-
mophores dispersed in polymer, have a larger r33 coefficient
because of the stability of the material under poling. The design
paradigm of chromophores covalently attached in a local
network appears to overcome the frustration commonly observed
in dipolar glasses that has previously limited the maximum
achievable chromophore density and resultant electro-optic
activity. However the degree of order observed in these systems
is still well below that of the theoretical maximum predicted
by analytic theory. Subtle changes in molecular architecture may
be able to minimize the inter- and intramolecular electrostatic
interactions that attenuate order, leading to materials with
previously unrealized electro-optic activity. The framework of
the MC calculations presented herein provide a tool for quickly
assessing the influence of changes in molecular architecture on
the overall structure of bulk ONLO materials. It is our hope
that the work presented will accelerate the development of new
optical materials and devices through the careful integration of
theory, experiment, and rational design.
1
in quantitative yield and used without further purification. H NMR
(300 MHz, CDCl3): δ 7.91 (d, J ) 15 Hz, 3H), 7.58-7.52 (m, 15H),
7.37 (d, J ) 8.7 Hz, 6H), 7.08 (d, J ) 15.6 Hz, 3H), 7.01 (s, 3H), 6.96
(d, J ) 8.7 Hz, 6H) 6.93 (d, J ) 15.3 Hz, 3H), 6.77-6.74 (m, 12H),
6.60 (d, J ) 15.3 Hz, 3H), 4.91 (s, 6H), 3.95 (t, J ) 6.3 Hz, 6H), 3.86
(t, J ) 5.4 Hz, 6H), 3.6 (t, J ) 5.4 Hz, 6H), 3.09 (s, 9H), 2.35 (t, J )
7.5 Hz, 6H), 2.08 (s, 3H), 1.83-1.74 (m, 6H), 1.72-1.64 (m, 6H), 1.54-
1.45 (m, 6H) ppm. MALDI-TOF: m/z calcd 2437.78; found, [M +
H], 2438.1, [M+Na], 2461.040 (m/z).
Dendrimer PSLD_41. An oven dried, magnetically stirred, 100 mL
two-neck round-bottomed flask was charged with 3 (0.10 g, 0.041
mmol), dendron 1 (FD) (0.084 g, 0.164 mmol), 1,3-dicyclohexylcar-
bodiimide (0.038 g, 0.184 mmol), and DPTS (0.030 g, 0.20 mmol).
After 1 h of drying under a high vacuum, the mixture was dissolved in
freshly distilled THF (10 mL) and DCM (15 mL). The reaction was
stirred for 48 h and washed with NaCl (saturated), and the organic
layer was collected. The aqueous layer was extracted with DCM, and
the combined organics were washed with water, dried over MgSO4,
and condensed in vacuo. The dark-blue crude solid was purified by
silica gel column chromatography (2.5% THF/DCM) to yield 0.1 g
(0.025 mmol, 62%), of a deep-blue solid. 1H NMR (500 MHz,
CDCl3): δ 7.93, (d, J ) 15.5, 3H), 7.58-7.54 (m, 15H), 7.39 (d, J )
9 Hz, 6H), 7.21 (d, J ) 2.5 Hz, 6H), 6.99 (s, 3H), 6.98 (d, J ) 7 Hz,
6H), 6.96 (d, J ) 15.5 Hz, 3H), 6.87 (d, J ) 15.5 Hz, 3H), 6.83 (d, J
) 9 Hz, 6H), 6.77 (d, J ) 9 Hz, 6H), 6.71 (t, J ) 2.5 Hz, 3H), 6.66
(d, J ) 15.5 Hz, 3H), 4.99 (s, 12H), 9.86 (dd, J1 ) 13 Hz, J2 ) 6.5
Hz, 6H), 4.54 (t, J ) 5.5 Hz, 6H), 3.93 (t, J ) 6.5 Hz, 6H), 3.86 (t, J
) 5.5 Hz, 6H), 3.13 (s, 9H), 2.36 (t, J ) 7.5 Hz, 6H), 2.09 (br-s, 3H),
1.82-1.76 (m, 6H), 1.73-1.67 (m, 6H), 1.53-1.47 (m, 6H), ppm. MALDI-
TOF: m/z calcd 3926.83; found, [M + H], 3927.26, [M + Na], 3950.25
(m/z). Anal. Calcd for C200H135F39N12O24S3: C, 61.16; H, 3.46; N,
4.28%. Found: C, 60.86; H, 3.25; N, 4.46%. UV-vis: λmax (CHCl3)
) 726 nm; λmax (film) ) 720 nm. DSC: Tg) 103 °C
Thin Film Fabrication Techniques and EO Measurements. Real
time pole and probe r33 measurement details have been reported
previously.19 Samples of each material were prepared by solution spin-
casting onto ITO-coated glass slides gold electrodes (d ≈ 200 nm) were
then deposited atop the films. EO measurements were performed at λ
) 1300 nm, and r33 measurements were recorded after cooling and
removal of the poling field. Values were calculated by sine-wave fitting
of lock-in-amplifier and direct current detector response curves as a
function of the relative phase angle (Ψsp) between TE and TM. Values
for r33 were then calculated from Ic and Im values using
Experimental Section
General Synthesis. All solvents were purified by distillation prior
to use unless otherwise stated. Commercially available chemicals were
used as received unless otherwise stated. All alkylithium reagents were
titrated prior to use. Glassware was base treated and oven or flame
dried. All reactions were performed under inert atmosphere. Amorphous
polycarbonate, APC (poly[bisphenol A carbonate-co-4,4′-(3,3,5-tri-
methylcyclohexyl-idene)diphenol carbonate]), was purchased from
Sigma Aldrich and purified by repeated precipitaion from a THF
solution into methanol followed by filtration and vacuum drying before
use.
2-[4-(2-{5-[2-(4-{[2-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-meth-
yl-amino}-phenyl)-vinyl]-3-hydroxymethyl-thiophen-2-yl}-vinyl)-3-
cyano-5-phenyl-5-trifluoromethyl-5H-furan-2-ylidene]-malononi-
trile (Chromophore 1). This compound was prepared following
literature procedures that were slightly modified to include a single
hydroxy-ethyl donor functionality for attachment of the outer dendron
in PSLD_41. Complete synthetic details are available online in the
Supporting Information.19,20
1,1,1-Tris-(6-hexanoic acid-4-phenyl) Ethane (2). The triacid
dendrimer core was synthesized according to literature procedure.19
Dendrimer PSLD_33. An oven dried, magnetically stirred, 100 mL
two-neck round-bottomed flask was charged with 1,1,1-Tris-(6-hexanoic
acid-4-phenyl) ethane (2) (0.221 g, 0.341 mmol), chromophore (1)
(0.820 g, 1.13 mmol), 1,3-dicyclohexylcarbodiimide (0.260 g, 1.26
mmol), and DPTS (0.10 g, 0.341mmol). After 1 h of drying under a
high vacuum, the mixture was dissolved in freshly distilled THF (10
mL) and DCM (15 mL). The reaction was stirred for 48 h and washed
with NaCl (saturated), and the organic layer was collected. The aqueous
layer was extracted with DCM, and the combined organics were washed
with water, dried over MgSO4, and condensed in vacuo. The dark-
blue crude solid was purified by silica gel column chromatography
(5% THF/ DCM) to yield 0.477 g (50%) of a deep blue solid. 1H NMR
(300 MHz, CDCl3): δ 7.89 (J ) 15.3 Hz), 7.58-7.54 (m, 15H), 7.39
(d, J ) 9 Hz, 6H), 7.13 (d, J ) 15.9 Hz, 3H), 7.03 (s, 3H), 6.98, (d,
J ) 8.7 Hz, 6H), 6.96 (d, J ) 15.9 Hz, 3H), 6.77 (d, J ) 8.7 Hz, 6H),
6.68 (d, J ) 8.7 Hz, 6H), 6.64 (d, J ) 15.3 Hz, 3H), 4.92 (d, J ) 3
Hz, 6H), 3.94 (t, J ) 6.3 Hz, 6H), 3.81 (t, J ) 6 Hz, 6H), 3.56 (t, J )
6 Hz, 6H), 3.10 (s, 9H), 2.35 (t, J ) 7.2 Hz, 6H), 2.09 (br-s, 3H),
1.87-1.79 (m, 6H), 1.72-1.67(m, 6H), 1.55-1.49 (m, 6H), 0.89 (s, 27H),
0.03 (s, 18H), ppm. MALDI-TOF: m/z calcd 2780.04; found, [M +
Na], 2804.476 (m/z). Anal. Calcd for C155H159F9N12O15S3Si3: C, 66.93;
H, 5.76; N, 6.04%. Found: C, 67.92; H, 5.96; N, 5.89%. UV-vis:
λmax (CHCl3) ) 759 nm; λmax (film) ) 734 nm. DSC: Tg ) 96 °C
Deprotection of PSLD_33 (3). A 50 mL round-bottomed flask is
charged with PSLD_33 (0.19 g) and acetone was added to dissolve (4
(n2 - sin2 θ)1/2
3λIm
r33
)
Im/Ic
4πVmIcn2
sin2 θ
where Vm is measured directly at the sample electrodes during poling.20
Acknowledgment. The authors acknowledge the support of
the STC-MDITR Program of the National Science Foundation
(Grant DMR0120967) and NSF (Grant DMR-0092380). Support
from the Air Force Office of Scientific Research under AFOSR-
(F49620-03-1-0110-P000), as well as from the DARPA MOR-
PH program Phase I ((N) 14-04-10094), is also gratefully
acknowledged.
Supporting Information Available: Complete synthetic and
characterization details for chromophore 1 as well as representa-
tive thermal and refractive index analyses. This material is
JA068322B
9
7530 J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007