(NHC)Pd(triethylamine)Cl2 (NHC= N-Heterocyclic Carbene) as Precatalyst
for the Synthesis of Poly(triarylamine)s
Reiner Sebastian Sprick,1 Mario Hoyos,2 Ming-Tsz Chen,2 Michael Lewis Turner,*1 Oscar Navarro*2,3
1
Organic Materials Innovation Centre, School of Chemistry, The University of Manchester, Manchester, M13 9PL, UK.
2
Department of Chemistry, University of Hawaii at Manoa, Honolulu HI 96822-2275, USA.
4
Current address: Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, 28006, Madrid, Spain.
3
Current address: Department of Chemistry, University of Sussex, Brighton, BN1 9QJ, UK.
Correspondence to: O. Navarro (o.navarro@sussex.ac.uk) and M.L. Turner (michael.turner@manchester.ac.uk)
SUPPORTING INFORMATION
Table of Contents
Experimental Procedures
SI1
References
SI2
Polymer Characterization: 1H NMR, MALDI-TOF, GPC, UV-Vis and Photoluminescence
SI3
FETs Results
SI11
EXPERIMENTAL PROCEDURES
Procedure for the synthesis of 4,4’-dichlorobiphenyl:1,2 Inside a glove box, 1-chloro-4-iodobenzene (7.90 g,
33.1 mmol), 4-chlorophenylboronic acid (4.94 g, 31.6 mmol), Pd(PPh3)4 (0.69 g, 0.6 mmol), NaOtBu (9.11 g,
0.094 mol) and toluene (200 mL) were added to an oven-dried 500 mL Schlenk flask, containing a magnetic
stir bar. The flask was capped with a glass stopper, removed from the glove-box and placed in an oil bath at
85 ˚C for 24 h. When GC analysis showed total conversion of the boronic acid, the toluene was removed
under reduced pressure and the product was purified by flash chromatography (silica gel, petroleum ether
40-60 °C) to give 4,4’-dichlorobiphenyl as a crystalline white solid (6.41 g, 91 %). Rf = 0.9 (petroleum ether
40-60 °C, UV). 1H NMR (300 MHz, CDCl3) δ 7.48 (d, 4H, ArH), 7.40 (d, 4H, ArH).
Device fabrication: Highly doped n++ silicon on which a 300 nm thick oxide layer had been thermally grown,
were cut into ca 1 × 1 cm pieces and cleaned by washing and ultrasonication for 5 minutes with deionized
water, acetone, methanol and 2-propanol. Substrates were cleaned by UV/Ozone surface treatment for 20
minutes then 75 µL of n-octadecyltrichlorosilane in 1,1,2-trichloroethene (3 mM solution) was spin-coated
at 3000 rpm for 10 seconds on the cleaned substrates. This was repeated twice before the substrates were
heated for 20 minutes on a hotplate at 105 °C in air. Substrates were cleaned by wiping off any excess n-
SI1
octadecyltrichlorosilane with a methanol soaked tissue and this cleaning was followed by rinsing and
ultrasonication with 2-propanol and acetone. The contact angle was checked using a drop of deionized
water before spin-coating 100 µL of the polymer solution (10 mg mL-1 solution in 1,1,2-trichloroethene,
filtered using a 0.45 µm syringe filter) at 3000 rpm for 60 seconds under ambient conditions. Substrates
were then dried at 80 ˚C for 2 hours before gold source and drain electrodes (50 nm) were thermally
evaporated under high vacuum conditions (<10-6 Torr) on the organic semiconductor layer through a
shadow mask with multiple devices of channel width (W = 2000 µm) and channel length (L = 60 µm).
FET characterisation: FET properties were measured using an Agilent E5270B precision measurement
E5270B 8 Slot precision measurement mainframe coupled to an Agilent E5287A atto level High Resolution
Module. Contacts were made using Karl Süss PH100 manual microprobes. Output characteristics were
obtained at a constant gate voltage VG between 0 V and -60 V; Transfer characteristics at a constant drain
voltage VSD = -60 V, varying the gate voltage (VG) from -60 to +20 V. The saturated hole mobility and the
threshold voltage were calculated from a plot of the square root of the drain current versus gate voltage
according to the following equation:
𝐼𝐷 =
𝜇𝐹𝐸𝑇 𝑊Ci
2𝐿
(𝑉𝐺 − 𝑉𝑇ℎ )2
(1)
Where W is the width of the channel (2 mm), L the length of the channel, Ci the equivalent capacitance of
the dielectric and VTh the threshold voltage. Measurements were performed at room temperature in air
and in the dark. Capacitance was determined by measuring representative MIM (metal-insulator-metal)
capacitors on an Agilent E4981A capacitance analyser for OTS treated SiO2 with gold (50 nm) evaporated as
top contact.
REFERENCES
1.
H.-J. Lehmler, L. W. Robertson, Chemosphere 2001, 45, 137-143.
2.
M. Yanagisawa, K. Hayamizu, O. Yamamoto, Magn. Reson. Chem. 1987, 25, 184-186.
SI2
CHARACTERIZATION
Figure S1. 1H NMR spectrum of 4,4’-dichlorobiphenyl.
SI3
GPC Traces
Figure S2. GPC traces of polymerization of 2,4-dimethylaniline and 4,4’-dibromobiphenyl carried out using 4
mol% of (IPr)Pd(TEA)Cl2.
Figure S3. GPC trace of polymerization of 2,4-dimethylaniline and 4,4’-dibromobiphenyl carried out using
1 mol% (IPr)Pd(TEA)Cl2. Conditions: 2,4-dimethylaniline (1 mmol), 4,4’-dibromobiphenyl (1 mmol), NaOtBu
(3 mmol), (IPr)Pd(TEA)Cl2 (1 mol%), toluene (3 mL), 100 ˚C.
SI4
1
H NMR, MALDI-TOF MS
Figure S4. 1H NMR spectrum of polymer P1 (Table 1, entry 7).
Figure S5. 1H NMR spectrum of polymer P1 (Table 1, entry 11).
SI5
Figure S6. MALDI-TOF MS spectrum of P1 (Table 1, entry 11), showing -H/2,4-dimethylaniline end-groups as
the main series (*) and -H/-H end-groups (#).
Figure S7. 1H NMR spectrum of polymer P2.
SI6
Figure S8. MALDI-TOF MS spectrum of polymer P2. Polymer showing –H / 2,4-dimethylaniline end-groups
(*),-H / -H end-groups (#), -2,4-dimethylaniline / anisole end-groups (v) and -2,4-dimethylaniline / 2 ×
anisole end-groups (x).
Figure S9. 1H NMR spectrum of polymer P3.
SI7
Figure S10. MALDI-TOF MS spectrum of polymer P3. Polymer showing –H / -4-methoxy-2-methylaniline
end-groups (*),-H / -H end-groups (#), -H/ anisole end-groups ($) and -4-methoxy-2-methylaniline / anisole
end-groups (v).
Figure S11. 1H NMR spectrum of polymer P4.
SI8
Figure S12. MALDI-TOF MS spectrum of polymer P4. Polymer showing –H / -4-methoxy-2-methylaniline
end-groups (*),-H / -H end-groups (#), -H/ anisole end-groups ($) and -4-methoxy-2-methylaniline / anisole
end-groups (v).
SI9
UV-Vis and Photoluminescence
a)
b)
Figure S13. UV/Vis and PL spectra of P1 a) synthesized with (IPr)Pd(allyl)Cl (orange) and (IPr)Pd(TEA)Cl2
(black) in dichloromethane solution. P1 synthesized with b) dibromobiphenyl (orange) and dichlorobiphenyl
(black).
SI10
FETs Results
Figure S14. Transfer characteristics (left) and output characteristics (right) in top-gate / bottom-contact
devices of P1 synthesized from dibromobiphenyl (Table 1, entry 7).
SI11