J. Phys. Chem. 1996, 100, 17079-17082
17079
Organic Mixed Valence Systems. II. Two-Centers and Three-Centers Compounds with
Meta Connections around a Central Phenylene Ring
Jacques Bonvoisin* and Jean-Pierre Launay
Groupe Electronique Mol e´ culaire, CEMES, CNRS, 29 rue Jeanne MarVig, F-31055 Toulouse Cedex, France
Wouter Verbouwe, Mark Van der Auweraer, and Frans Carl De Schryver
Chemistry Department, Celestijnenlaan 200F, 3001 HeVerlee, Belgium
X
ReceiVed: April 12, 1996; In Final Form: August 7, 1996
This paper is devoted to two new aromatic polyamines derived from p-EFTP (5′-(4-(bis(4-ethylphenyl)-
amino)phenyl)-N,N,N′,N′-tetrakis(4-ethylphenyl)-1,1′:3′,1′′-terphenyl-4,4′′-diamine) and exhibiting meta con-
nections around a central phenylene ring. In p-EFDP (5′-phenyl-(N,N,N′,N′-tetrakis(4-ethylphenyl)-1,1′:3′,1′′-
terphenyl-4,4′′-diamine) there are only two redox sites instead of three. Upon partial oxidation, an intervalence
transition is observed from which an electronic coupling very similar to the one of p-EFTP is obtained. In
p-FADP (N,N,N′,N′,N′′,N′′-hexakis(4-ethylphenyl)-1,1′:3′,1′′-terphenyl-4,4′′,5′ triamine) one finds two redox
sites of the N,N′-bis(4-ethylphenyl)-4-aminobiphenyl type, and one redox site of the triphenylamine type.
The analysis of the electrochemical behavior and of the intervalence transitions in the mono- and dioxidized
species allows the distinction among the different types of electron transfer.
Introduction
temperature of the mixture had fallen to 0 °C, a solution of
0
.098 g (1.42 mmol) of sodium nitrite in 1 mL of water was
In a previous paper, we described intervalence transitions in
partly oxidized aromatic polyamines of the p-EFTP type
added from a dropping funnel in the course of 15 min. After
treatment with hypophosphorus acid, as described in ref 3, the
desired disubstituted amino triphenylbenzene (5′-phenyl-1,1′:
[
p-EFTP ) 5′-(4-(bis(4-ethylphenyl)amino)phenyl)-N,N,N′,N′-
1
tetrakis(4-ethylphenyl)-1,1′:3′,1′′-terphenyl-4,4′′-diamine]. This
study allowed in particular the determination of the effective
coupling parameter (Vab) between redox sites, using the char-
acteristics (position, intensity, width) of the intervalence transi-
tion.
3
′,1′′-terphenyl-4,4′′-diamine) could be separated from the
mixture of mono-, di-, and triamino substituted triphenylbenzene
and triphenylbenzene by chromatography through a silica gel
column with 1:2 ethyl acetate:hexane as the eluting solvent. In
a second step, 5′-phenyl-1,1′:3′,1′′-terphenyl-4,4′′-diamine was
reacted with 4-ethylphenyl iodide in the presence of Cu-bronze,
K2CO3, and tris(dioxa-3,6-heptyl)amine (TDA) in boiling o-
p-EFTP 3 is a three-site system with 3-fold symmetry (cf.
Scheme 1). Since then, new compounds of the same general
type have been synthesized, which allow interesting compari-
sons. One is a two-redox-sites system, i.e., p-EFDP 1, so that
we can now compare in a detailed way the cases of two sites
and three sites and test the theory of the three-site system. The
other is a asymmetrical molecule with three redox sites, i.e.,
p-FADP 2 in which the 3-fold symmetry is lost (see Scheme
2
dichlorobenzene as described previously. The crude product
was purified by column chromatography using silica and 1:2
dichloromethane:hexane as the eluting solvent. This provided
a white crystalline product. Melting point: 216 °C. Mass
+
1
spectrum m/z (%): 244 (M , 53), 210 (100), 171 (15). H NMR
(
(
7
400 MHz, CDCl3): δ 1.25 (t, J ) 7.6 Hz, 12 H, CH3), δ 2.63
q, J ) 7.8 Hz, 8 H, CH2), δ 7.07 (d, J ) 9 Hz, 8 H, ArH), δ
1
). As will be shown below, such a system allows the
discrimination between two kinds of electron transfer.
.11 (d, J ) 9 Hz, 8 H, ArH), δ 7.12 (d, J ) 9 Hz, 4 H, ArH),
δ 7.37 (t, J ) 7 Hz, 1 H, ArH), δ 7.46 (t, J ) 7 Hz, 2 H, ArH),
δ 7.53 (d, J ) 9 Hz, 4 H, ArH), δ 7.68-7.72 (m, 5 H, ArH).
Experimental Section
13
C NMR (400 MHz, CDCl3): δ 15.5 (CH3), 28.2 (CH2), 122.8,
24.1, 124.7, 127.3, 127.4, 127.8, 128.6, 128.8 (CH, Ar), 134.2,
39.0, 141.4, 141.8, 142.1, 145.4, 147.8 (C, Ar).
p-EFDP (5′-phenyl-(N,N,N′,N′-tetrakis(4-ethylphenyl)-1,1′:
1
1
3
1
′,1′′-terphenyl-4,4′′-diamine) was synthesized starting from
,3,5-tris(4-aminophenyl)benzene, which was prepared previ-
2
p-FADP (N,N,N′,N′,N′′,N′′-hexakis(4-ethylphenyl)-1,1′:3′,1′′-
ously. The first step implies the decomposition of an amino
group by the formation of a diazonium salt with sodium nitrite
terphenyl-4,4′′,5′ triamine) was obtained by courtesy of Agfa-
Gevaert. The preparation of p-EFTP (5′-(4-(bis(4-ethylphenyl)-
amino)phenyl)-N,N,N′,N′-tetrakis(4-ethylphenyl)-1,1′:3′,1′′-
terphenyl-4,4′′-diamine) has been reported earlier.2
UV-vis-near-IR spectra were recorded with a Shimadzu
UV-3101 PC spectrophotometer. Cyclic voltammetry curves
were recorded with an Electrokemat 2000 system from ISMP
Technologie using a platinum wire as the working electrode,
CH2Cl2 (HPLC grade) as the solvent, and tetrabutylammonium
hexafluorophosphate (0.1 M) as the supporting electrolyte.
Oxidation experiments necessary to generate the mixed-
valence forms of 1 and 2 were performed by electrolysis with
coulometry.
followed by the substitution of the diazonium group by a
hydrogen using hypophosphorus acid.3 In a 50 mL beaker were
placed 6.7 mL of water and 0.5 mL of concentrated hydrochloric
acid. This solution was heated on a oil bath to boiling. When
the desired temperature was reached, the heating source was
removed and 0.5 g (1.42 mmol) of 1,3,5-tris(4-aminophenyl)-
benzene was added. The beaker was then placed in an ice-
salt mixture, and its content was stirred mechanically until the
temperature has dropped to about 15 °C. At this point 0.5 mL
more of concentrated hydrochloric acid was added. When the
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Abstract published in AdVance ACS Abstracts, October 1, 1996.
S0022-3654(96)01093-3 CCC: $12.00 © 1996 American Chemical Society