Symmetrical and unsymmetrical ferrocenyl perylenediimides: Design, synthesis and properties

Article abstract of DOI:10.1016/j.dyepig.2016.07.006

Symmetrical and unsymmetrical ferrocenyl perylenediimides (PDIs) 1–6 were designed and synthesized by the Sonogashira cross-coupling and nucleophilic aromatic substitution (S_NAr) reactions. The PDIs were functionalized with ferrocenyl moiety through varying spacers to study the effect of one and two ferrocenyl units on their photophysical and electrochemical properties. The ferrocenyl unit and PDI were coupled through 3-phenylacetylene, 4-phenylacetylene and 4-phenoxy linkages to tune the electronic properties. The ferrocenyl PDIs show red shift in the absorption with the increasing conjugation. The efficient electronic communication between the ferrocenyl unit and PDI leads to the strong charge-transfer from donor ferrocene to the acceptor PDI core and quenching of fluorescence. The electrochemical studies reveal the effect of spacers on the Donor-Acceptor (D-A) interactions and electronic energy levels. The oxidation of ferrocenyl PDIs 1–6 are harder than free ferrocene indicating the considerable delocalization of ferrocenyl electrons on the PDI moiety. The experimental observations were adequately supported by theoretical calculations.

Full text of DOI:10.1016/j.dyepig.2016.07.006

Dyes and Pigments 134 (2016) 164e170
Contents lists available at ScienceDirect
Dyes and Pigments
journal homepage: www.elsevier.com/locate/dyepig
Symmetrical and unsymmetrical ferrocenyl perylenediimides: Design,
synthesis and properties
Bhausaheb Dhokale, Thaksen Jadhav, Yuvraj Patil, Rajneesh Misra*
Department of Chemistry, Indian Institute of Technology Indore, 452 020, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Symmetrical and unsymmetrical ferrocenyl perylenediimides (PDIs) 1e6 were designed and synthesized
by the Sonogashira cross-coupling and nucleophilic aromatic substitution (SNAr) reactions. The PDIs
were functionalized with ferrocenyl moiety through varying spacers to study the effect of one and two
ferrocenyl units on their photophysical and electrochemical properties. The ferrocenyl unit and PDI were
coupled through 3-phenylacetylene, 4-phenylacetylene and 4-phenoxy linkages to tune the electronic
properties. The ferrocenyl PDIs show red shift in the absorption with the increasing conjugation. The
efficient electronic communication between the ferrocenyl unit and PDI leads to the strong charge-
transfer from donor ferrocene to the acceptor PDI core and quenching of fluorescence. The electro-
chemical studies reveal the effect of spacers on the Donor-Acceptor (D-A) interactions and electronic
energy levels. The oxidation of ferrocenyl PDIs 1e6 are harder than free ferrocene indicating the
considerable delocalization of ferrocenyl electrons on the PDI moiety. The experimental observations
were adequately supported by theoretical calculations.
Received 17 May 2016
Received in revised form
28 June 2016
Accepted 4 July 2016
Available online 5 July 2016
Keywords:
Perylenediimide
Ferrocene
Donor-Acceptor
Charge transfer
Photophysics
Electrochemistry
© 2016 Elsevier Ltd. All rights reserved.
1. Introduction
variety of photonic applications [7].
The PDIs can be functionalized at imide as well as at the bay
The Perylene dyes are one of the promising candidate for
organic electronics [1]. Perylene dyes belong to the class of rylene
family, a well-known industrial colorant [2]. The perylenediimide
(PDI) and its derivatives exhibit spectacular photonic and electro-
chemical properties, and high n-channel mobility [3]. The well
position. The node on the nitrogen atom of imide position obstructs
the electronic communication between the substituent and the PDI
core. Therefore the imide substituents have negligible effect on the
optical properties of the PDI. On the other hand, the bay position
can be substituted through wide range of spacers to tune the
properties of PDIs substantially [8].
communicating and highly planar
p-aromatic framework of PDI
gives them high electron mobility. The high electron affinity of two
The major problem associated with the perylene dye is the poor
imide groups leads to low lying LUMOs, which makes PDI a strong
solubility due to extensive
be overcome by introducing the long, branched alkyl chains at
imide position which eliminates the staking and improves the
p-p staking interactions. This hurdle can
electron acceptor for Donor-Acceptor (D-A) systems [4]. The
p-
conjugated Donor-Acceptor (D-A) molecular systems exhibit strong
photovoltaic performance, information storage, charge separation,
lower HOMO-LUMO gap, red shifted absorption and strong Non-
linear Optical (NLO) response [5].
Another important component of D-A system is the donor.
Ferrocene is a promising donor among the wide range of electron
rich moieties. It is highly reversible redox active centre with the
well-established optical and electrochemical properties [6]. The
strong NLO response of ferrocene leads to extensive use in wide
p-p
solubility without affecting the electronic properties of PDIs.
Neil Champness group have explored the di-substituted ferro-
cenyl PDI as multistate redox architectures for promising 3-D
memory storage applications [9]. The PDIs were decorated with
ferrocenyl moiety at the imide positions and studied for redox or
photoinduced electron transfer molecular fluorescent switches
[10]. The non-fluorescent neutral ferrocenyl PDIs were reversibly
switched to highly fluorescent entity by ferric perchlorate chemi-
cally or by electrochemical oxidation. In our previous report we
have explored the optical and electrochemical properties of un-
symmetrical mono-substituted ferrocenyl PDIs [11]. We were
further interested to explore the effect of substituting one and two
* Corresponding author.
E-mail address: rajneeshmisra@iiti.ac.in (R. Misra).
http://dx.doi.org/10.1016/j.dyepig.2016.07.006
0143-7208/© 2016 Elsevier Ltd. All rights reserved.

B. Dhokale et al. / Dyes and Pigments 134 (2016) 164e170
165
ferrocenyl unit on the PDI core through different spacers. Herein we
2. Results and discussion
have designed and synthesized unsymmetrical (1e3) and sym-
metrical (4e6) ferrocenyl PDIs by incorporating one and two fer-
rocenyl units on PDI respectively (Scheme 1). We chose the spacers
3-phenylacetylene, 4-phenylacetylene and 4-phenoxy linkage
which can offer the systematic tuning of the electronic communi-
cation between the ferrocenyl units and the PDI core.
The ferrocenyl PDIs 1e6 were synthesized by the Sonogashira
cross-coupling and nucleophilic aromatic substitution (SNAr) re-
action of bromo PDIs with respective ferrocenyl counterparts. The
mono and di-bromo PDIs 7e8 were obtained by the bromination
reaction of perylenediimide 9, which in turn was obtained from the
O
O
O
O
N
O
NH2
Molten Imidazole
Cu(OAc)2
O
O
O
O
N
O
10
9
Br2
CHCl3
O
N
O
O
N
O
O
N
O
O
N
O
Ar
Ar
Ar
Br
Br
+
Br
PdCl2(PPh3)2,
CuI,
PdCl2(PPh3)2,
CuI,
Ar
Ar
Toluene, TEA,
80 oC, 8 h
Toluene, TEA,
80 oC, 8 h
O
N
O
O
N
O
O
N
O
O
N
O
8
4 - 5
1 - 2
7
K2CO3
K2CO3
18-crown-6-ether
Toluene,
100 oC, 2 h
18-crown-6-ether
Toluene,
100 oC, 2 h
Fe
Fe
Ar =
Ar =
Fe
Fe
1
2
4
5
O
N
O
O
N
O
Fe
Fe
O
O
O
Fe
O
N
O
O
N
O
3
6
Scheme 1. Synthesis of symmetrical and unsymmetrical ferrocenyl PDIs 1e6.

166
B. Dhokale et al. / Dyes and Pigments 134 (2016) 164e170
imidation reaction of perylenedianhydride 10 in molten imidazole
as solvent (Scheme 1). The bromination reaction of imidated PDI 9
with bromine in chloroform yielded the mixture of mono-bromo
and di-bromo PDIs (7 and 8). The mono-bromo and di-bromo
PDIs were separated by column chromatography. The di-bromo
PDI was mixture of 1,6- and 1,7-isomers and used as mixture
throughout the studies.
The Pd-catalyzed Sonogashira cross-coupling reaction of mono-
bromo PDI 7 with respective ferrocenyl alkyne resulted ferrocenyl
PDIs 1 and 2 in 65 and 61% yields respectively. Similarly, the
Sonogashira coupling reaction of di-bromo PDI 8 with respective
ferrocenyl alkynes resulted the ferrocenyl PDIs 4 and 5 in 59 and
62% yields respectively.
incorporation of ferrocenyl unit on the PDI, red shifts the absorp-
tion band with increasing -conjugation. The characteristic
p
vibronic pattern of PDI was weakened in the ferrocenyl PDIs to a
shoulder in higher energy region due to the extended conjugation
and substituent induced non-planarity of the PDI core [12]. The
unsymmetrical mono-substituted ferrocenyl PDIs absorb in
530e545 nm region whereas the symmetrical di-substituted fer-
rocenyl PDIs absorb in 538e570 nm region. The redshift in the
absorption spectra of symmetrical di-substituted ferrocenyl PDIs
compared to the unsymmetrical mono-substituted ferrocenyl PDIs
can be assigned to enhanced conjugation. The phenoxy linked
ferrocenyl PDIs 3 and 6 show absorption at 530 and 538 nm
respectively, which is blue shifted than the alkynylated ferrocenyl
PDIs.
The 4-phenylacetylene linked symmetrical mono-substituted
ferrocenyl PDI 2 and unsymmetrical di-substituted ferrocenyl PDI
5 show CT band as a shoulder at lower energy region indicating the
presence of charge transfer interaction (Fig. 1(B)). Such charge
transfer band was not observed in ferrocenyl PDIs 1, 3, 4 and 6
indicating that, the 4-phenylacetylene show superior electronic
communication compared to the 3-phenylacetylene and 4-
phenoxy linkage. The solvatochromism studies were performed
on the PDIs 2 and 5 (Fig. S6). The 3-phenylacetylene linked sym-
metrical and unsymmetrical ferrocenyl PDIs show red shifted ab-
sorption than the 4-phenylacetylene linked ferrocenyl PDIs.
To understand the trend in the electronic absorption spectra and
The nucleophilic aromatic substitution reaction of 4-ferrocenyl
phenol with mono-bromo and di-bromo PDIs (7 and 8) in the
presence of K2CO3 resulted ferrocenyl PDIs 3 and 6 in 68 and 70%
yields respectively. All the ferrocenyl PDIs were well characterized
by 1H, 13C NMR and HRMS techniques.
2.1. Photophysical properties
The photophysical properties of ferrocenyl PDIs 1e6 and PDI 9
were recorded in dichloromethane (Fig. 1) and the corresponding
data are shown in Table 1. The PDI 9 show intense absorption band
at 524 nm with distinct bands in higher energy region corre-
sponding to the characteristic vibronic pattern of PDI. The
1.5
2.0
B
A
9
2
5
1.5
9
1
1.0
4
1.0
0.5
0.0
0.5
0.0
300
400
500
600
700
800
300
400
500
600
700
800
Wavelength (nm)
Wavelength (nm)
1.0
0.5
0.0
D
C
9
1
2
3
4
5
6
9
3
6
300
400
500
600
700
800
500
550
600
650
700
750
Wavelength (nm)
Wavelength (nm)
Fig. 1. Comparison of normalized electronic absorption spectra of parent PDI 9 with symmetrical and unsymmetrical ferrocenyl PDIs 1 and 4 (A); 2 and 5 (B); 3 and 6 (C) and their
emission spectra at 0.1 absorption, exited at 487 nm in dichloromethane (D).

B. Dhokale et al. / Dyes and Pigments 134 (2016) 164e170
167
Table 1
Photophysical properties of ferrocenyl PDIs 1e6 and parent PDI 9.a
b
PDI
lmax (nm)
3
)
lem (nm)c
4d
HOMO-LUMO gap (eV)e
9
1
2
3
4
5
6
524
546
541
529
571
563
540
4.4
4.9
4.6
4.5
4.2
4.7
4.9
532, 573
536, 573
533, 577
554, 596
e
0.89
0.05
0.05
0.12
e
2.53
2.11
2.14
2.26
2.16
2.04
2.34
e
e
e
e
a
Recorded in DCM.
b
c
Determined at lmax
Excited at lmax
.
.
d
e
Determined using Rhodamine 6G as standard.
From DFT calculation.
charge transfer interaction the representative TD-DFT calculations
were performed on unsymmetrical ferrocenyl PDIs 1e3 (ESI and
Fig. S7). The simulated absorption spectra resemble with the
experimental absorption with deviation by only 10e15 nm, and the
trend in lmax matches well with experimental data (Table 1). The
both simulated and experimental lmax values of the unsymmetrical
ferrocenyl PDIs follow the order 1 > 2 > 3. The TD-DFT calculations
also support the strength of charge transfer band. The oscillator
strengths of the first electronic transition from HOMO to LUMO are
predicted to be 0.0080, 0.1619 and 0.0265 for PDIs 1, 2 and 3
respectively, which indicates that the charge transfer interaction in
PDI 2 is most prominent, in 3 it is minor, whereas in 1 it’s almost
absent. This is in good agreement with the existence or absence of
the CT band observed in the absorption spectra, which show charge
transfer band in PDI 2 and not in PDI 3.
prominently decreases the fluorescence quantum yield compared
to the weakly communicating 4-phenoxy spacer (in ferrocenyl
PDI 3).
The absorption spectra of ferrocenyl PDIs 1e6 in solid state was
recorded (Fig. S5). The absorption spectra suggest the different
packing behaviour depending on the nature of linkage. The effect of
symmetrical and unsymmetrical substitution on the solid state
absorption of the PDIs 1e6 is minor.
2.2. Electrochemical properties
The electrochemical properties of ferrocenyl PDIs 1e6 and PDI 9
were recorded in dichloromethane using Glassy carbon as working
electrode, Platinum wire as counter electrode and Ag/AgCl as
reference electrode in 0.1
M
tetrabutylammoniumhexa-
The emission behaviour of ferrocenyl PDIs 1e6 and PDI 9 was
recorded in dichloromethane (Fig. 1)(D). The incorporation of one
ferrocenyl unit decreases the fluorescence quantum yield of PDI,
whereas the incorporation of two ferrocenyl units completely
quenches the fluorescence of PDIs. The quenching of fluorescence is
attributed to the fast non-radiative deactivation of the excited state
through the charge transfer from donor ferrocene to the acceptor
PDI [13]. The nature of spacers plays an important role in tuning the
electronic communication between the ferrocene and PDI. The
superior electronic communication shows stronger charge transfer
interaction, and leads to quenching of fluorescence, whereas the
weak electronic communication hinders the charge transfer inter-
action and retains the fluorescence quantum yield. The strongly
communicating phenylacetylene spacer (in ferrocenyl PDI 1 and 2)
fluorophosphate as supporting electrolyte (Figs. 2 and S1eS4). The
potentials were referenced against the Fc/Fcþ couple. The electro-
chemical potentials are displayed in Table 2. The parent PDI show
two reduction waves and the free ferrocene shows one oxidation
wave only. The ferrocenyl PDIs 1e6 show two reduction waves and
one oxidation wave, which indicates that the reduction waves
correspond to the reduction of PDI unit whereas the oxidation wave
corresponds to the oxidation of ferrocenyl moiety. The higher
oxidation potential of ferrocenyl PDIs compared to free ferrocene,
indicates the considerable delocalization of donor ferrocenyl elec-
trons to the acceptor PDI moiety. This reveals the strong D-A
interaction between ferrocene and the PDI moiety.
There is slight variation in the oxidation and reduction poten-
tials of 3-phenylacetylene and 4-phenylacetylene linked ferrocenyl
16.0μ
14.0μ
12.0μ
16.0μ
14.0μ
12.0μ
Ferrocenyl PDI 1
10.0μ
Ferrocenyl PDI 4
10.0μ
CV
DPV
CV
DPV
8.0μ
8.0μ
6.0μ
4.0μ
2.0μ
0.0
6.0μ
4.0μ
2.0μ
0.0
-2.0μ
-4.0μ
-2.0μ
-4.0μ
-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8
-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8
Potential Vs Fc/Fc+ (V)
Potential Vs Fc/Fc+ (V)
Fig. 2. Comparison of electrochemical behaviour of ferrocenyl PDIs 1 and 4.

168
B. Dhokale et al. / Dyes and Pigments 134 (2016) 164e170
Table 2
(the B3 exchange functional [14] and LYP correlation functional
[15]). The calculated electronic energy levels and the frontier mo-
lecular orbitals are shown in Fig. 3. The energy level diagram shows
that the HOMO-LUMO gap steadily decreases with the increasing
conjugation and is in agreement with the observed absorption
spectrum. The frontier molecular orbital plots reveal that the
LUMOs are localized on the PDI core indicating the strong electron
acceptor nature of PDI. In ferrocenyl PDIs 1, 3, 4 and 6 the HOMO is
localized on donor ferrocenyl moiety whereas in 4-phenylacetylene
linked ferrocenyl PDIs 2 and 5 the HOMO is distributed over the
ferrocene unit and PDI moiety indicating efficient distribution of
electron density. The HOMO-LUMO distribution reveals the strong
D-A interaction in ferrocenyl PDIs.
Electrochemical properties of parent PDI 9 and ferrocenyl PDI 1e6.a
PDI
Eoxid (V)
E1 (V)
E2 (V)
red
red
9
1
2
3
4
5
6
e
ꢀ1.07
ꢀ1.02
ꢀ1.02
ꢀ1.10
ꢀ0.97
ꢀ0.98
ꢀ1.14
ꢀ1.28
ꢀ1.22
ꢀ1.22
ꢀ1.30
ꢀ1.16
ꢀ1.17
ꢀ1.32
0.06
0.06
0.01
0.07
0.05
0.01
a
Determined by electrochemical analysis in 0.1 M solution of Bu4NPF6 in CH2Cl2.
(1.0 ꢁ 10ꢀ4 M) at 100 mV Sꢀ1 Scan rate, Vs Fc/Fcþ
.
PDIs, which suggest the minor effect of meta or para linkage on the
HOMO and LUMO energy levels of PDI but, slightly easier oxidation
of 4-phenylacetylene linked ferrocenyl PDIs 2 and 5 than 3-
phenylacetylene linked ferrocenyl PDIs supports the observed
charge transfer band in absorption studies and TD-DFT calculations.
There is much difference in the oxidation and reduction potentials
of phenylacetylene and phenoxy linked ferrocenyl PDIs indicating
the poor electronic communication of phenoxy linkage than phe-
nylacetylene linkages.
The comparison of voltammetric analysis of mono and di-
substituted ferrocenyl PDIs show that ferrocenyl oxidation cur-
rent in symmetrical di-substituted ferrocenyl PDIs is much higher
than in unsymmetrical mono-substituted ferrocenyl PDIs. This in-
dicates the simultaneous two electron oxidation of two ferrocenyl
units in symmetrical ferrocenyl PDIs 4e6 and single electron
oxidation of single ferrocenyl unit in unsymmetrical ferrocenyl PDIs
1e3.
3. Conclusions
The symmetrical and unsymmetrical ferrocenyl PDIs were
designed and synthesized by Sonogashira cross coupling and
nucleophilic aromatic substitution (SNAr) reactions. The ferrocenyl
PDIs show strong D-A interactions and the strength of D-A inter-
action depend on the nature of the spacer. The symmetrical di-
substituted ferrocenyl PDIs show red shifted absorption than the
unsymmetrical mono substituted ferrocenyl PDIs due to the
extended
p-conjugation. The 4-phenylacetylene linked ferrocenyl
PDIs 2 and 5 show charge transfer band as a shoulder at lower
energy region indicating the presence of strong charge transfer
interaction. The strong D-A interactions were also evident from the
electrochemical studies. The higher ferrocenyl oxidation potential
in ferrocenyl PDIs than free ferrocene reveals the considerable
delocalization of donor ferrocenyl electrons to the acceptor PDI
moiety. The frontier molecular orbital distribution indicates the
2.3. DFT calculations
strong D-A interaction and efficient p-electron delocalization.
The broad absorption in visible region, low HOMO-LUMO gap
and strong D-A interaction in ferrocenyl PDIs 1e6 make them a
potential candidate for photovoltaic and NLO applications. The re-
sults presented here will be useful in the design and synthesis of
new molecular systems for efficient optoelectronic applications.
The density functional theory (DFT) calculations on the ferro-
cenyl PDIs 1e6 were performed to understand the electronic en-
ergy levels and orbital distribution using Gaussian 09 programme
at B3LYP/6-31G(d) level for C, H, N, O and the Lanl2DZ level for Fe
-1
-2
-3
-4
-5
-6
PDI 1
2
3
4
5
6
-7
Fig. 3. The frontier molecular orbital distribution and electronic energy levels in ferrocenyl PDIs 1e6.

B. Dhokale et al. / Dyes and Pigments 134 (2016) 164e170
169
4. Experimental section
CuI (7.4 mg, 0.039 mmol), and ferrocenyl alkyne (0.97 mmol) were
added, and the reaction mixture was stirred at 70 ꢂC for 8 h.
Following cooling to room temperature, the reaction mixture was
evaporated to dryness on rotary evaporator and dissolved in CH2Cl2
and filtered through a small pad of silica. The crude product was
purified by Column chromatography on 230e400 mesh size silica
in 5:1 mixture of chloroform: hexane, and recrystallized in chlo-
roform methanol mixture to yield desired product.
4.1. General methods
Chemicals were used as received unless otherwise indicated. All
oxygen or moisture sensitive reactions were performed under ni-
trogen/argon atmosphere using standard schlenk method. Trie-
thylamine (TEA) was received from commercial source and distilled
on KOH prior to use. 1H NMR (400 MHz), and 13C NMR (100 MHz)
spectra were recorded on the Bruker Avance (III) 400 by using
CDCl3 as solvent. 1H NMR chemical shifts are reported in parts per
million (ppm) relative to the solvent residual peak (CDCl3, 7.26 ppm
and Acetone-d6 2.05 ppm). Multiplicities are given as: s (singlet),
d (doublet), t (triplet), q (quartet), dd (doublet of doublets), m
(multiplet), and the coupling constants, J, are given in Hz. 13C NMR
chemical shifts are reported relative to the solvent residual peak
(CDCl3, 77.36 ppm). UVevisible absorption spectra of all com-
pounds were recorded on a PerkinElmer’s LAMBDA 35 UV/Vis
Spectrophotometer. Fluorescence spectra of all the compounds
were recorded on a Horiba Jobin Yvon Floromax 4P spectropho-
tometer. HRMS were recorded on Brucker-Daltonics, micrOTOF-Q II
mass spectrometer. The voltammograms were recorded on
CHI620D electrochemical analyzer in dichloromethane solvent and
0.1 M TBAF6 as supporting electrolyte. The electrodes used were
glassy carbon as working electrode, Pt wire as counter electrode
and the saturated calomel electrode as reference electrode. The
potentials were referenced against Fc/Fcþ as per IUPAC guidelines
[16].
4.2.2.1. Ferrocenyl PDI 4. Red-purple solid. Yield: 59% (271 mg); 1H
NMR (CDCl3, 400 MHz, ppm):
d
10.12 (d, J ¼ 8 Hz, 2H), 8.87e8.70 (m,
4H), 7.72 (s, 8H), 4.57e7.35 (m, 8H), 4.73 (s, 4H), 4.40 (s, 4H),
4.19e4.10 (m, 14H), 1.98 (m, 2H), 1.42e1.32 (m, 16H), 0.99e0.90 (m,
12H). 13C NMR (CDCl3, 100 MHz, ppm): 163.4, 163.1, 140.6, 137.7,
135.5,133.8,130.2,129.3,129.1, 128.9,127.5, 127.4, 127.2, 127.1,126.8,
123.0, 122.2, 121.9, 120.0, 99.8, 90.8, 83.8, 69.9, 69.6, 66.8, 44.4, 38.1,
31.0, 28.9, 24.3, 23.3, 14.3, 10.8. TOF HRMS m/z ¼ 1182.3993
(calculated for C76H66Fe2N2O4 ¼ 1182.3721). UVeVis (in CH2Cl2):
lmax (ε [Mꢀ1 cmꢀ1]): 571 nm (42000).
4.2.2.2. Ferrocenyl PDI 5. Red-purple solid. Yield: 62% (285 mg); 1H
NMR (CDCl3, 400 MHz, ppm):
d
10.12 (d, J ¼ 8 Hz, 2H), 8.84e8.70
(m, 4H), 7.54 (s, 8H), 4.73 (s, 4H), 4.42 (s, 4H), 4.21e4.09 (m, 14H),
1.98 (m, 2H), 1.43e1.34 (m, 16H), 0.99e0.91 (m, 12H). 13C NMR
(CDCl3, 100 MHz, ppm): 163.9, 163.5, 153.1, 152.9, 142.2, 140.7, 137.7,
132.1, 130.5, 128.1, 127.8, 126.4, 123.1, 122.0, 120.8, 119.3, 91.4, 85.8,
84.1, 83.8, 70.0, 69.9, 66.9, 38.2, 31.0, 29.9, 28.9, 24.3, 23.3, 14.3, 10.8.
TOF
HRMS
m/z
¼
1182.3706
(calculated
for
C76H66Fe2N2O4
¼
1182.3721). UVeVis (in CH2Cl2): lmax (ε
4.2. Synthetic procedures
[Mꢀ1 cmꢀ1]): 563 nm (47).
4.2.1. Generalized procedure for the Sonogashira reaction of 1-
bromo-perylenediimide and ferrocenyl alkynes
4.2.3. Procedure for the nucleophilic aromatic substitution reaction
of 1-bromo-perylenediimide (7) and 4-ferrocenylphenol
N,N0-Di-(2-ethyl-1-hexyl)-1-bromoperylene-3,4:9,10-
N,N0-Di-(2-ethyl-1-hexyl)-1-bromoperylene-3,4:9,10-
tetracarboxylic acid bisimide (7) (100 mg, 0.14 mmol) was dissolved
in a mixture of dry toluene (13 mL) and dry triethylamine (6.5 mL)
in an Ar atmosphere. PdCl2-(PPh3)2 (10 mg, 0.014 mmol), CuI (3 mg,
0.015 mmol), and ferrocenyl alkyne (0.1582 mmol) were added, and
the reaction mixture was stirred at 70 ꢂC for 8 h. Following cooling
to room temperature, the reaction mixture was evaporated to
dryness on rotary evaporator and dissolved in CH2Cl2 and filtered
through a small pad of silica. The crude product was purified by
column chromatography on 230e400 mesh size silica in 4:1
mixture of chloroform: hexane, and recrystallized in chloroform
methanol mixture to yield desired product.
tetracarboxylic acid bisimide (7) (100 mg, 0.14 mmol) was dissolved
in a mixture of dry toluene (10 mL) in an Ar atmosphere. To this, 4-
ferrocenyl phenol (44.2 mg, 0.16 mmol), 18-crown-6 ether
(152.6 mg, 0.58 mmol), and K2CO3 (39.88 mg, 0.29 mmol), was
added and the reaction mixture was heated at 100 ꢂC for two hours.
After completion of the reaction the reaction mixture was cooled to
room temperature and washed with water. The organic layer was
concentrated on rotary evaporator and the crude product was pu-
rified by column chromatography on silica gel in chloroform:hex-
ane (1:1) mixture followed by precipitation in chloroform diethyl
ether mixture to yield desired product.
4.2.1.1. Ferrocenyl PDI 1. Red-purple solid. Yield: 65% (84 mg); 1H
4.2.3.1. Ferrocenyl PDI 3. Red-purple solid. Yield: 68% (87 mg); 1H
NMR (CDCl3, 400 MHz, ppm):
d
10.19 (d, J ¼ 8 Hz), 8.67e8.52 (m,
NMR (CDCl3, 400 MHz, ppm):
d
9.39 (d, J ¼ 8 Hz, 1H), 8.55e8.41 (m,
6H), 7.57e7.52 (m, 4H), 4.75 (s, 2H), 4.44 (s, 2H), 4.2e4.14 (m, 9H),
1.94 (m, 2H), 1.42e1.33 (m, 16H), 0.97e0.88 (m, 12H). 13C NMR
(CDCl3, 100 MHz, ppm): 163.2,163.0,162.9,162.5,140.8,137.8, 133.3,
132.8, 132.5, 130.2, 129.0, 128.94, 128.86, 128.3, 127.6, 127.5, 162.2,
162.1, 125.6, 123.0, 122.93, 122.86, 122.5, 122.4, 121.8, 121.6, 119.6,
101.4, 90.7, 83.7, 69.8, 69.6, 66.7, 44.25, 44.22, 38.0, 30.8, 28.7, 26.9,
24.1, 23.18, 23.16, 14.2, 10.61, 10.57. TOF HRMS m/z ¼ 898.3452
(calculated for C58H54FeN2O4 ¼ 898.3433). UVeVis (in CH2Cl2):
lmax (ε [Mꢀ1 cmꢀ1]): 546 nm (49000). Fluorescence (in CH2Cl2,
lex ¼ 487 nm): 573 nm 4F: 0.0119.
6H), 8.21 (s, 1H), 7.56 (d, J ¼ 8 Hz, 2H), 7.10 (d, J ¼ 8 Hz, 2H), 4.62 (s,
2H), 4.34 (s, 2H), 4.11e4.02 (m, 9H), 1.91 (m, 2H), 1.39e1.29 (m,
16H), 0.94e0.86 (m, 12H). 13C NMR (CDCl3, 100 MHz, ppm): 163.8,
163.6, 163.5, 163.0, 156.1, 152.7, 137.2, 134.0, 133.9, 133.4, 131.8,
130.6, 129.5, 128.8, 128.5, 128.2, 126.5, 125.4, 124.2, 124.1, 123.4,
123.0, 122.9, 122.8, 122.3, 122.1, 119.9, 84.8, 69.8, 69.2, 66.8, 44.5,
44.3, 38.1, 38.0, 30.9, 28.8, 24.2, 23.23, 23.22, 14.3, 10.8, 10.7. TOF
HRMS m/z ¼ 890.3408 (calculated for C56H54FeN2O5 ¼ 890.3378).
UVeVis (in CH2Cl2): lmax (ε [Mꢀ1 cmꢀ1]): 529 nm (45000). Fluo-
rescence (in CH2Cl2, lex ¼ 538 nm): 554 nm 4F: 0.12.
4.2.2. Generalized procedure for the Sonogashira reaction of 1, 7-di-
bromo-perylenediimide and ferrocenyl alkynes
4.2.4. Procedure for the nucleophilic aromatic substitution reaction
of 1-bromo-perylenediimide (7) and 4-ferrocenylphenol
N,N0-Di-(2-ethyl-1-hexyl)-1,
7-di-bromoperylene-3,4:9,10-
N,N0-Di-(2-ethyl-1-hexyl)-1,
7-di-bromoperylene-3,4:9,10-
tetracarboxylic acid bisimide (8) (300 mg, 0.39 mmol) was dis-
solved in a mixture of dry toluene (13 mL) and dry triethylamine
(6.5 mL) in an Ar atmosphere. PdCl2-(PPh3)2 (27.3 mg, 0.039 mmol),
tetracarboxylic acid bisimide (8) (100 mg, 0.13 mmol) was dis-
solved in a mixture of dry toluene (10 mL) in an Ar atmosphere. To
this, 4-ferrocenyl phenol (79.4 mg, 0.28 mmol), 18-crown-6 ether

170
B. Dhokale et al. / Dyes and Pigments 134 (2016) 164e170
J Appl Phys 1997;81:6804e8.
(118.8 mg, 0.78 mmol), and K2CO3 (71.8 mg, 0.52 mmol), was added
and the reaction mixture was heated at 100 ꢂC for two hours. After
completion of the reaction the reaction mixture was cooled to room
temperature and washed with water. The organic layer was
concentrated on rotary evaporator and the crude product was pu-
rified by column chromatography on silica gel in chloroform:hex-
ane (1:1) mixture followed by precipitation in chloroform diethyl
ether mixture to yield desired product.
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NMR (CDCl3, 400 MHz, ppm):
d
9.58 (d, J ¼ 8 Hz, 2H), 8.62 (d, J ¼ 8 Hz,
2H), 8.38 (s, 2H), 7.51 (d, J ¼ 8 Hz, 4H), 7.09 (d, J ¼ 8 Hz, 4H), 4.65
(s, 4H), 4.36 (s, 4H), 4.13e4.06 (m, 14H), 1.91 (m, 2H), 1.35e1.34 (m,
16H), 0.90e0.85 (m, 12H). 13C NMR(CDCl3, 100 MHz, ppm): 163.9,
163.5, 155.4, 154.5, 153.3, 148.1, 136.8, 133.6, 132.2, 130.5, 129.5,
129.0, 128.4, 127.6, 125.3, 124.2, 124.05, 123.99, 122.4, 119.7, 69.9,
69.3, 69.2, 66.9, 53.6, 44.5, 38.1, 30.9, 28.9, 24.2, 23.2, 14.2, 10.8. TOF
HRMS m/z ¼ 1166.3625 (calculated for C72H66Fe2N2O6 ¼ 1166.3619).
UVeVis (in CH2Cl2): lmax (ε [Mꢀ1 cmꢀ1]): 540 nm (49000).
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Acknowledgments
R. M. thanks DST EMR/2014/001257, New Delhi for financial
support. B. D. and T. J. thank CSIR project no 01(2795)/14/EMR-II
and UGC, Y. P. thanks Ministry of Human Resource Development
(MHRD), New Delhi for their fellowships.
Appendix A. Supplementary data
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Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.dyepig.2016.07.006.
(c) Misra R, Gautam P, Sharma R, Mobin SM. Tetrahedron Lett 2013;54:381e3.
(d) Jadhav T, Maragani R, Misra R, Sreeramulu V, Rao DN, Mobin SM. Dalton
Trans 2013;42:4340e2.
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