Synthesis and characterization of some octaalkyl substituted lead phthalocyanines and unexpected variations in lead lability arising from the position of substituents and their chain length

Article abstract of DOI:10.1142/S108842461350020X

The preparation of some peripherally substituted (2,3,9,10,16,17,23,24) and non-peripherally substituted (1,4,8,11,15,18,22,25) octaalkyl lead(II) phthalocyanines with different alkyl chain lengths (6, 7, 8 or 9 carbons) is described and a comparison of some of their properties reported. X-ray structure analyses of the isomeric peripheral and non-peripheral octakis(octyl) phthalocyaninato lead(II) compounds reveal a greater degree of distortion of the ligand ring system from planarity in the former derivative. The series of peripherally substituted octaalkyl lead(II) phthalocyanines exhibit columnar liquid crystal behavior whereas the non-peripherally substituted isomers do not. The lability of the lead ion was investigated using ¹H NMR spectrometry under a specific set of conditions (8.8 × 10^-4 M solutions of the phthalocyanine in d₈-toluene containing d ₄-acetic acid 2.06 × 10^-5 M). All the compounds underwent acid catalyzed demetalation at rates dependent upon the location of the substituents and, more surprisingly, the chain length of the alkyl groups. Under these conditions the lead ion within each of the peripherally substituted octaalkyl lead phthalocyanines was more labile than that in the non-peripherally substituted isomer.

Full text of DOI:10.1142/S108842461350020X

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2013; 17: 511–521
DOI: 10.1142/S108842461350020X
Published at http://www.worldscinet.com/jpp/
Synthesis and characterization of some octaalkyl substituted
lead phthalocyanines and unexpected variations in lead
lability arising from the position of substituents and their
chain length
Lydia X. Sosa-Vargasa,b, Isabelle Chambriera, Colin J. MacDonalda, Simon J. Colesc,
Graham J.Tizzardc, Andrew N. Cammidge*a and Michael J. Cook*a◊
a School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
b Centre for Research on Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and
Technology-Kansai, Osaka, Japan
c EPSRC National Crystallography Service, School of Chemistry, University of Southampton, Southampton SO17
1BJ, United Kingdom
Dedicated to Professor Özer Bekaroğlu on the occasion of his 80th birthday
Received 28 January 2013
Accepted 15 February 2013
ABSTRACT: The preparation of some peripherally substituted (2,3,9,10,16,17,23,24) and non-
peripherally substituted (1,4,8,11,15,18,22,25) octaalkyl lead(II) phthalocyanines with different alkyl
chain lengths (6, 7, 8 or 9 carbons) is described and a comparison of some of their properties reported.
X-ray structure analyses of the isomeric peripheral and non-peripheral octakis(octyl)phthalocyaninato
lead(II) compounds reveal a greater degree of distortion of the ligand ring system from planarity in
the former derivative. The series of peripherally substituted octaalkyl lead(II) phthalocyanines exhibit
columnar liquid crystal behavior whereas the non-peripherally substituted isomers do not. The lability of
the lead ion was investigated using 1H NMR spectrometry under a specific set of conditions (8.8 × 10-4 M
solutions of the phthalocyanine in d8-toluene containing d4-acetic acid 2.06 × 10-5 M). All the compounds
underwent acid catalyzed demetalation at rates dependent upon the location of the substituents and, more
surprisingly, the chain length of the alkyl groups. Under these conditions the lead ion within each of the
peripherally substituted octaalkyl lead phthalocyanines was more labile than that in the non-peripherally
substituted isomer.
KEYWORDS: liquid crystalline phthalocyanines, lead lability, X-ray structures of phthalocyanines.
sensors [1–6] and more recently have been investigated
INTRODUCTION
for use in photovoltaic [7–9] and semiconducting
Lead(II) metalated phthalocyanine derivatives
devices [10–13], as well as for optical limiting [14,15].
(PbPcs), unsubstituted and substituted, are materials that
In addition, during early work on the development
have been of interest for a number of applications. They
of phthalocyanine columnar liquid crystals, Skoulios
showed early promise as the active component in gas
et al. demonstrated that 2,3,9,10,16,17,23,24- (the sites
referred to hereafter as peripheral) octa-alkoxymethyl
substituted PbPc derivatives exhibited mesophase behavior
SPP full member in good standing
[16,17].From a structural viewpoint,PbPcs are interesting
because the size of the lead ion is such that it is not fully
accommodated within the central cavity of the normally
*Correspondence to: Andrew N. Cammidge, email:
a.cammidge@uea.ac.uk or Michael J. Cook, email m.cook@
uea.ac.uk
Copyright © 2013 World Scientific Publishing Company

512
L.X. SOSA-VARGAS ET AL.
planar ligand. Thus it lies partially above (or below) the
plane of the four isoindolene nitrogen atoms and this in
turn can lead to distortion of the ligand. The unsubstituted
derivative occurs in two polymorphic forms [18,19]; both
molecules adopt saucer shaped conformations but with
different degrees of displacements of the Pb ion from the
convex side of the ligand. The two forms have markedly
different molecular packing. In contrast, examples of
non-peripheral (1,4,8,11,15,18,22,25-) octa-substituted
derivatives tend to adopt saddle-shaped conformations
with varying degrees of ring distortion and displacement
of the lead atom from the inner N4 plane. Thus, the lead
atom of the n-hexyl, isopentyl [20] and n-hexylsulfanyl
[21] substituted PbPcs are displaced from the N4 plane
by 1.286, 1.272 and 1.303 Å respectively. Particularly
distorted PbPcs bearing aryl substituents have been
reported by Kobayashi et al. [22].
During earlier work at UEA on synthesising non-
peripherally substituted PbPcs for optical limiting studies[15,
20,21]wenotedvaryingdegreesoflabilityofthePbionduring
chromatographic purification. This was particularly apparent
for octa-alkyl substituted compounds but not for an octa-
alkylsulfanyl derivative [21]. The literature on lead lability
in PbPcs is somewhat limited which is surprising in view
of the number of their applications that have been explored.
Barrett et al. first reported the loss of lead from unsubstituted
PbPc under treatment with concentrated sulfuric acid [23] as
early as 1936 but subsequent work by Collins et al. [24] did
not support these findings. More recently, Moham Kumar
and Achar carried out a UV-vis spectroscopic study of the
demetalation of unsubstituted PbPc and its tetra-nitro and
tetra-amino derivatives in 36N, 30N and 28N sulfuric acid.
The compounds have greater stability in 36N sulfuric acid but
were all demetalated within 7 days [25]. In passing, we note
that the demetalation of a single phthalocyanine molecule
has recently been achieved using a tunnelling microscope tip
applied to an ultrathin film of PbPc deposited on Ag [26].
In the present paper we explore in greater depth
the lability of the Pb ion in two homologous series of
octaalkyl substituted PbPcs viz peripheral (p) substituted
compounds and their non-peripheral (np) substituted
isomers using d4-acetic acid as catalyst. Demetalation
was followed by 1H NMR spectrometry.
RESULTS AND DISCUSSION
Preparation and characterization of the compounds
Non-peripherally (1,4,8,11,15,18,22,25) substituted
octa-n-alkylleadphthalocyaninesderivatives.Earlierthe
UEA group prepared two examples of these compounds,
the octahexyl and octaoctyl derivatives [20], denoted here
as np-6PbPc and np-8PbPc (see Scheme 1). The route to
these,andthatusedinthepresentworktoextendtheseries,
commences with the known 1,4-dialkylphthalonitriles
and their conversion to the previously reported octaalkyl
substituted metal-free phthalocyanine derivatives [27]
followed by metalation using lead acetate. The four
lead metalated phthalocyanines so obtained, np-6PbPc,
np-7PbPc, np-8PbPc and np-9PbPc, were purified by
chromatographic separation over neutral alumina as the
stationary phase due to the decomposition/loss of lead
that occurs upon use of silica-gel [21].
Peripherally
(2,3,9,10,16,17,23,24)
substituted
octa-n-alkyl lead phthalocyanines derivatives. Four
compounds, isomeric with those above and denoted as
p-6PbPc, p-7PbPc, p-8PbPc and p-9PbPc (Scheme 2)
have not apparently been reported elsewhere although
examples of the corresponding metal-free derivatives
have been synthesized by other groups from the
corresponding 4,5-dialkylphthalonitriles. Several routes
to these precursors have been reported in the literature
based on Diels–Alder cycloadditions and various cross-
coupling reactions [28–34]. However, the synthesis of the
desired range of the 4,5-dialkyl phthalonitriles proved to
be unexpectedly challenging using these known routes,
especially when reactions were carried out on larger
scales (>10 g). The synthetic route developed in this
research has the advantages of using inexpensive starting
R
R
R
R
N
N
N
R
R
R
R
R
R
R
R
NH
N
N
N
CN
CN
i
iii
N
N
N
N
Pb
ii
N
HN
N
N
R
R
N
R
R
R
R
R
hexyl
heptyl
octyl
nonyl
np-6H2Pc
np-7H2Pc
np-8H2Pc
np-9H2Pc
np-6PbPc
np-7PbPc
np-8PbPc
np-9PbPc
Scheme 1. (i) Li metal, pentan-1-ol, reflux; (ii) Glacial acetic acid, rt; (iii) Pb(OAc)2·3H2O, pentan-1-ol, reflux
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 512–521

SYNTHESIS AND CHARACTERIZATION OF SOME OCTAALKYL SUBSTITUTED LEAD
513
Br
Br
R
R
R
R
OMe
OMe
OMe
OMe
OH
OH
final step utilized a minor adaptation of Hanack’s
employment of a cross-coupling reaction to
replace the triflate groups by nitrile groups [30].
In our hands, we found that care must be taken
to follow closely these reaction conditions, as
even slight divergences resulted in a low yield of
the phthalonitrile. Fortunately if the conversion
to nitrile is low, the precursor material can be
recovered easily and re-used. Conversion of the
4,5-dialkyl phthalonitriles into the corresponding
metal-free phthalocyanines and thence to the lead
metalated derivatives was straightforward.
i
ii
iii
R = hexyl, heptyl, octyl or nonyl throughout
R
R
R
R
CN
CN
OTf
OTf
iv
v
vi
R
R
R
R
Characterization. The metal-free Pcs and
PbPc derivatives shown in Schemes 1 and 2
were all satisfactorily characterized by H NMR
spectrometry, UV-visible and IR spectroscopy,
CHN elemental analysis, and MALDI-ToF mass
spectrometry. In addition two derivatives were
further characterized by single crystal X-ray
diffraction, vide infra.
R
R
R
R
R
N
N
N
Pb
N
1
NH
N
N
N
N
N
vii
N
N
N
N
HN
N
R
R
R
R
R
R
R
The investigation of liquid crystal behavior
exhibited by these compounds above was
undertaken using a combination of differential
scanning calorimetry (DSC) and polarized light
optical microscopy (POM). In summary, all
the metal-free derivatives exhibited mesophase
behavior, confirming previous results where
available [35]. A comparison of the mesophase
temperature ranges, i.e. from the crystal phase
(Cr) to the isotropic liquid (I), exhibited by the
p- and np-series of metal-free compounds is presented in
Fig. 1.Among the PbPc derivatives only the p-substituted
compounds exhibited liquid crystal behavior. Data in
Fig. 2 summarizes their mesophase ranges.
p-6H2Pc
p-7H2Pc
p-8H2Pc
p-9H2Pc
p-6PbPc
p-7PbPc
p-8PbPc
p-9PbPc
Scheme 2. (i) Pd(dppf)2Cl2, RMgBr, Et2O; (ii) HBr/acetic acid, reflux;
(iii) Tf2O in lutidine, DCM, -78 °C; (iv) Pd2(dba)3, dppf, Zn(CN)2 in
DMF, 70 °C; (v) Li metal, pentan-1-ol, reflux; (vi) Glacial acetic acid,
rt; (vii) Pb(OAc)2·3H2O, pentan-1-ol, reflux
materials such as veratrole, and the first three synthetic
steps employ simple functional group transformations.
Yields of these reactions are almost quantitative. The
Fig. 1. Plots comparing the temperatures for the crystal (Cr) to mesophase and the mesophase to isotropic liquid (I) transitions for
the peripherally substituted (p) and non-peripherally substituted (np) series of metal-free derivatives. All temperatures, measured by
DSC, refer to the third cooling cycle
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 513–521

514
L.X. SOSA-VARGAS ET AL.
Fig. 2. Plots showing the temperatures for the crystal (Cr) to mesophase (red line) and the mesophase to isotropic liquid (I) transitions
(blue line) for the p-series of lead phthalocyanine derivatives. All temperatures were obtained by DSC and refer to the third cooling
cycle. The inset shows examples of the columnar mesophase (Col) textures observed using POM upon cooling from the isotropic
liquid. Colh refers to hexagonal packing. Melting point data for the non liquid-crystalline np-series of compounds can be found in
the Experimental section
POM analysis of the birefringence textures
indicated that the principal mesophase exhibited by the
compounds was columnar hexagonal (colh) although the
C9 derivatives also developed a columnar rectangular
structure (colr). Two of the lead derivatives p-8PbPc and
p-9PbPc appear to exhibit a glass phase which induces
unusually low crystallizing temperatures and a wide
mesophase range (Fig. 2).
Single crystal X-ray diffraction studies of p-8PbPc and
np-8PbPc show significant differences in the distortion
of the phthalocyanine core (Fig. 3). Thus the former is
slightly saddle shaped with the lead atom projecting at
1.034 Å out of the mean N4 plane with a mean Pb–N
distance of 2.37(5) Å. In contrast the ligand of np-8PbPc
is essentially planar with the Pb ion 1.231 Å out of the
N4 plane with a mean Pb–N distance of 2.34(8) Å. This
Fig. 3. X-ray structure determinations for p-8PbPc and np-8PbPc
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 514–521

SYNTHESIS AND CHARACTERIZATION OF SOME OCTAALKYL SUBSTITUTED LEAD
515
latter geometry differs significantly from that of the lower
homolog np-6PbPc reported earlier wherein the ligand is
distinctly saddle shaped [20].
21 spectral scans of a single compound over a period of
time. In the case of the series of np-PbPc compounds the
signals for the diasterotopic benzylic signals show well
separated multiplets, one of which is slowly overlapped
by the triplet arising from the newly generated np-H2Pc.
For analytical purposes, integration of the signals
arising from the aromatic protons was chosen for
monitoring the conversion of each PbPc into the
corresponding H2Pc. These data were then expressed
as a function of the decreasing concentration of PbPc,
measured from the ratio of the aromatic proton signals
for the PbPc and the H2Pc, with time; sample preparation,
loading and spectra processing times were taken into
account for the analysis.
Figure 5 shows the plot of ln[PbPc] against time over
four to six hours for the series of np-PbPcs, the straight
lines indicative of pseudo-first order kinetics with regard
to PbPc concentration. The rates of demetalation clearly
vary from one compound to another with no obvious
trend. However, these are not random results because the
same sequence of ease of demetalation was observed in
the preliminary experiments referred to above.
Demetalation studies using 1H NMR spectrometry
Following a number of trial experiments, a set of
conditions was chosen to enable monitoring of the
conversion of each PbPc into its H2Pc analog over
time using 1H NMR spectrometry. Solutions of the
octaalkyl lead phthalocyanines were prepared in NMR
tubes immediately prior to NMR monitoring. This
entailed adding a stock solution of d8-toluene containing
d4-acetic acid to a pre-weighed amount of a PbPc to
provide solutions of the phthalocyanines at a standard
concentration (8.8 × 10-4 M). A ratio of 290:1 acetic
acid to PbPc was used. The molarity of phthalocyanine
employed was to limit aggregation as far as possible
yet allow a satisfactory NMR signal to be accumulated
within a short time. Two regions of the 1H NMR spectra
were then monitored over time, viz 7–8 ppm and 4–5
ppm which contain the aromatic and benzylic signals
respectively. Figure 4 shows a representative series of
Figure 6 shows the corresponding output from
experiments with the peripherally substituted lead
phthalocyanines. Also included is a plot obtained for
lead tetraphenylporphyrin (PbTPP) which was measured
for comparative purposes. The plots are broadly linear
but the clearest difference from those shown in Fig. 5
is that demetalation is occurring much faster. Indeed, a
satisfactory range of measurements was obtained within
30 min. We attribute the minor divergences of some data
points from linearity to the quality of the NMR signal
intensity measurements, particularly for the metal-free
derivative. The aromatic proton signals for the latter were
often broadened indicating that the metal-free derivatives
were showing some degree of aggregation even at the
low concentrations of the solutions. This proved to be a
particular problem for the p-6PbPc derivative and indeed
just three data points were measured, not included in the
graph because they are considered to have a significant
error margin.
The calculated rate constants and t values are
½
presented in Table 1 for all the compounds bar p-6PbPc.
The lability of the lead ion in the PbPc compounds
induced by the presence of dilute acid, and more
particularly the variation in this property from one
compound to another, is both unexpected and surprising.
At the level of the present experiments it is difficult to fully
rationalize the results. The data for the np-PbPcs suggest
that there is an “odd-even” effect with regard to chain
length. In earlier studies on the solubility and aggregation
of a series of np-ZnPcs “odd-even” effects were noted. In
particular the np-6ZnPc and np-8ZnPc were a little more
prone to aggregation than the np-7ZnPc and np-9ZnPc
compounds [36]. Thus we may postulate that different
levels of limited aggregation from one PbPc compound
to another may be an external factor that affects lead
Fig. 4. Twenty-one successive scans of 1H NMR spectra
collected over time revealing the conversion of np-8PbPc into
np-8H2Pc. Top shows signals for the aromatic protons with the
benzylic proton signals below
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 515–521

516
L.X. SOSA-VARGAS ET AL.
Fig. 5. Plots of ln[PbPc] concentration vs. time for the np-PbPc compounds
Fig. 6. Plot of ln[PbPc] vs. time of the p-PbPc compounds and tetraphenylporphyrin (TPP)
lability. We have reported elsewhere a comparison of a
conformations in the solution phase, it is evident that
there is no set specific displacement of the Pb ion from
the N4 plane of the ligand ring and variations of this
parameter within the series may also be reflected in the
solution phase and may also be a factor with regard to
lead ion lability. Studies of the lability of the lead ion in
examples of these compounds in the solid state, e.g. as
thin films, may shed light on this matter. For the present,
we can note that the present results have implications for
the handling of these compounds and in particular for the
choice of the chromatographic stationary phase used for
the purification processes.
non-peripherally and peripherally substituted octa-alkyl
Pcs which showed that the latter is less soluble and more
prone to aggregation in a hydrocarbon solvent [37].
This may well extend to the present series of np-PbPc
and p-PbPc compounds and would thus suggest that
the probably greater propensity for aggregation among
the p-PbPc series is a potential destabilizing factor with
regard to lead ion retention. There may of course be
internal structural features that come into play as well.
Although solid state structures, of which two are reported
in the paper, are not strictly relevant to the molecular
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 516–521

SYNTHESIS AND CHARACTERIZATION OF SOME OCTAALKYL SUBSTITUTED LEAD
517
Table 1. Comparative data for the demetalation of p- and
np-octaalkyl lead Pc derivatives and tetraphenyl porphyrin in
acidic media (CD3COOD in d8-toluene)
“periodical experiment” set up. For the non-peripheral
series, an array of 10 spectra was collected at intervals
of approximately 30 min time. On the other hand,
spectra from the peripheral series were collected at
approximately 2 min intervals. The length of each interval
was determined from previous preliminary studies using
NMR and UV-visible spectroscopy to determine average
demetalation times for each series. Sample loading and
acquisition times are included in the intervals.
Rate constant
Compound
R2
k (1/s)
t , h
½
np-6PbPc
np-7PbPc
np-8PbPc
np-9PbPc
p-6PbPc
p-7PbPc
p-8PbPc
p-9PbPc
TPP
0.9990
0.9947
0.9992
0.9989
—
0.096
0.066
0.132
0.042
—
7.22
10.50
5.25
16.50
(0.2)*
0.07
General procedure for the preparation of
4,5-dialkylveratroles
0.9907
0.9912
0.9458
0.9403
10.55
8.18
4,5-Dioctylveratrole. 4,5-dibromoveratrole (10.0 g,
0.338 mol) and 1,1’-bis(diphenylphosphino)ferrocene
palladium(II) dichloride (1.38 g, 1.69 mmol, 5%) were
added to dry diethyl ether (5.0 mL) in a RBF under an
inert atmosphere. A solution of n-octylmagnesium iodide
in diethyl ether (70.0 mL, 3.44 M, 0.169 mol) was added
to the solid mixture via syringe at rt. Upon addition the
solution changes color to dark green, and then to mustard
yellow. This was then left to stir for a further 30 min and
the solution became viscous. The crude mixture was
quenched in water and the spent catalyst filtered off under
vacuum. The recovered filtrate was washed with dilute
HCl (2 × 50 mL), brine, and extracted with petroleum
ether. The organic solutions were then dried (Na2SO4) and
the solvent removed under reduced pressure. The resulting
title compound was purified by column chromatography
over silica gel (petroleum ether as eluent) to give the pure
product as a light orange oil (9.2 g, 75%). IR (neat): n,
0.08
5.74
0.12
3.17
0.22
* Estimated.
EXPERIMENTAL
General methods
1H NMR spectra were recorded on a Bruker 400
MHz spectrometer. 13C NMR spectra were recorded on
a Varian 300 Lambda spectrometer. Signals are quoted
in ppm as d downfield from tetramethylsilane (d = 0.00).
Ultra-violet spectra of the phthalocyanine derivatives
were recorded on a Hitachi U-3000 spectrophotometer
using toluene as solvent. IR spectra were recorded on
FTIR Nicolet AVATAR 360 spectrometer. MALDI-ToF
mass analysis was carried out using a Shimadzu MALDI-
ToF spectrometer with a TA1586Ade plate and DCTB
as matrix. The spectrometer was calibrated using non-
peripheral (C8H17)8 metal-free phthalocyanine. Elemental
analyses were submitted for novel compounds to the
service of Stephen Boyer at the London Metropolitan
University and results provided were within acceptable
error margins. Column chromatography was performed at
room temperature using Aldrich® neutral alumina, using
reagent grade solvents as eluents. Recrystallization of the
materials was carried out using HPLC grade methanol
and distilled dichloromethane. Grignard reagents were
prepared immediately prior to use following conventional
protocols. Experimental procedures for the synthesis of
the previously published np-H2Pcs [27] are not included.
X-ray diffraction was performed by the UK National
Crystallography Service at 119 beamline, Diamond Light
Source, according to a previously published procedure
[38]. Cell determination, data collection and treatment
were undertaken using CrystalClear-SM Expert 2.0 r7
(Rigaku, 2011). Structure solution was achieved using
SUPERFLIP and refined using SHELXL97.
1
cm-1 1465 (s, CO-Ar). H NMR (400 MHz, CDCl3): d,
ppm 6.65 (2H, s), 3.82 (6H, s), 2.53 (4H, t, J = 7.9), 1.57
(4H, m), 1.30 (20H, m), 0.90 (6H, t, J = 6.8). 13C NMR
(75 MHz, CDCl3): d, ppm 140.6, 132.8, 115.9, 113.9,
32.0, 31.5, 29.7, 29.4, 29.3, 22.9, 14.2.
4,5-Dihexylveratrole. Following the general
procedure the desired product was recovered as an amber
1
oil (4.03 g, 71%). H NMR (400 MHz, CDCl3): d, ppm
6.62 (2H, s), 3.80 (6H, s), 2.51 (4H, t, J = 7.8), 1.57 (4H,
m), 1.30 (12H, m), 0.90 (6H, t, J = 6.8).
4,5-Diheptylveratrole. Following the general
procedure the title compound was recovered as an amber
oil (3.67 g, 71%). IR (neat): n, cm-1 1464 (s, CO-Ar).
1H NMR (400 MHz, CDCl3): d, ppm 6.63 (2H, s), 3.80
(6H, s), 2.51 (4H, t, J = 7.9), 1.57 (4H, m), 1.32 (16H,
m), 0.89 (6H, t, J = 6.8). 13C NMR (75 MHz, CDCl3): d,
ppm 141.6, 132.6, 115.9, 114.0, 32.2, 29.7, 29.4, 29.4,
22.9, 14.1.
4,5-Dinonylveratrole. Following the general
procedure the title compound was recovered as an amber
oil (6.56 g, 70%). IR (neat): n, cm-1 1464 (s, CO-Ar). 1H
NMR (400 MHz, CDCl3): d, ppm 6.65 (2H, s), 3.82 (6H,
s), 2.53 (4H, t, J = 7.9), 1.57 (4H, m), 1.30 (24H, m),
0.89 (6H, t, J = 6.8). 13C NMR (75 MHz, CDCl3): d, ppm
140.6, 132.8, 115.8, 113.9, 32.0, 31.5, 29.7, 29.4–20.5
(≈ 4 signals), 14.1.
1
The H NMR spectral arrays were recorded on a
Bruker 500 MHz spectrometer using Bruker software’s
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 517–521

518
L.X. SOSA-VARGAS ET AL.
General procedure for the preparation of
4,5-dialkyldihydroxybenzenes
(neat): n, cm-1 837 (s, CF). 1H NMR (400 MHz, CDCl3):
d, ppm 7.18 (2H, s), 2.58 (4H, t, J = 7.9), 1.57 (4H, m),
1.30 (20H, m), 0.90 (6H, t, J = 7.3). 13C NMR (75 MHz,
CDCl3): d, ppm 140.7, 129.6, 117.9, 115.2, 31.9, 31.6,
30.1, 29.4, 29.4, 22.8.
4,5-Dihexyl-1,2-ditrifluoromethanesulfonyloxy-
benzene. Following the general procedure, the title
compound was obtained as a clear oil (4.73 g, 60%). IR
(neat): n, cm-1 835 (s, CF). 1H NMR (400 MHz, CDCl3):
d, ppm 7.18 (2H, s), 2.57 (4H, t, J = 7.9), 1.57 (4H, m),
1.31 (12H, m), 0.90 (6H, t, J = 7.3). 13C NMR (75 MHz,
CDCl3): d, ppm 143.3, 137.9, 123.7, 117.2, 32.5, 31.8,
30.7, 29.3, 22.7, 14.2.
4,5-Diheptyl-1,2-ditrifluoromethanesulfonyloxy-
benzene. Following the general procedure, the title
compound was obtained as a clear oil (6.05 g, 60%). IR
(neat): n, cm-1 835 (s, CF). 1H NMR (400 MHz, CDCl3):
d, ppm 7.18 (2H, s), 2.57 (4H, t, J = 7.9), 1.57 (4H, m),
1.30 (16H, m), 0.90 (6H, t, J = 7.3). 13C NMR (75 MHz,
CDCl3): d, ppm 143.2, 138.1, 123.7, 117.3, 32.44, 32.2,
30.0, 29.9, 29.6, 29.2, 22.8, 14.1.
4,5-Dinonyl-1,2-ditrifluoromethanesulfonyloxy-
benzene. Following the general procedure, the title
compound was obtained as a clear oil (7.68 g, 77%). IR
(neat): n, cm-1 834 (s, CF). 1H NMR (400 MHz, CDCl3):
d, ppm 7.18 (2H, s), 2.57 (4H, t, J = 7.9), 1.57 (4H, m),
1.32 (24H, m), 0.90 (6H, t, J = 7.3). 13C NMR (75 MHz,
CDCl3): d, ppm 143.2, 138.1, 123.6, 117.3, 32.9, 32.2,
31.4, 30.3, 29.9, 29.4, 29.1, 22.8, 14.0.
4,5-Dioctyl-1,2-dihydroxybenzene. 4,5-dioctyl-1,2-
dimethoxybenzene (12.0 g, 0.331 mol) was added to a
stirred mixture of hydrobromic and glacial acetic acid
(200.0 mL, 1:1) to give an emulsion. The light orange
emulsion was heated to reflux for 18 h under normal
atmosphere. The mixture turned dark brown in color
and was left to cool to room temperature. After cooling,
the product was washed with water (3 × 50 mL), brine
and extracted with dichloromethane. The organics were
dried (Na2SO4) and the solvent removed under reduced
pressure to give the pure product as a dark red oil (11.1
1
g, 83%) H NMR (400 MHz, CDCl3): d, ppm 6.63 (2H,
s), 5.20 (2H, s), 2.42 (4H, t, J = 7.8), 1.53 (4H, m), 1.31
(20H, m), 0.90 (6H, t, J = 6.9).
4,5-Dihexyl-1,2-dihydroxybenzene. Following the
general procedure, the product was recovered as a brown
1
oil (3.14 g, 95%). H NMR (400 MHz, CDCl3): d, ppm
6.62 (2H, s), 5.23 (2H, s), 2.42 (4H, t, J = 7.8), 1.55 (4H,
m), 1.31 (12H, m), 0.90 (6H, t, J = 6.9).
4,5-Diheptyl-1,2-dihydroxybenzene. Following the
general procedure, the title compound was recovered as
a dark brown oil (9.26 g, 78%). IR (neat): n, cm-1 2822
(sb, OH). 1H NMR (400 MHz, CDCl3): d, ppm 6.61 (2H,
s), 5.20 (2H, s), 2.43 (4H, t, J = 7.8), 1.55 (4H, m), 1.33
(16H, m), 0.91 (6H, t, J = 6.9). 13C NMR (75 MHz,
CDCl3): d, ppm 141.2, 133.8, 116.7, 32.3, 32.1, 31.4,
29.9, 29.7, 29.5, 22.9.
4,5-Dinonyl-1,2-dihydroxybenzene. Following the
general procedure, the title compound was recovered as
a dark brown oil (8.75 g, 79%). IR (neat): n, cm-1 2975
(sb, OH). 1H NMR (400 MHz, CDCl3): d, ppm 6.62 (2H,
s), 5.22 (2H, s), 2.43 (4H, t, J = 7.8), 1.56 (4H, m), 1.33
(24H, m), 0.90 (6H, t, J = 6.9). 13C NMR (75 MHz,
CDCl3): d, ppm 140.3, 134.2, 116.8, 32.3, 32.0, 31.6,
30.4, 30.0, 29.9, 29.8, 29.5, 23.1.
General procedure for the preparation of 4,5-
dialkylphthalonitriles
4,5-Dioctylphthalonitrile. To
bis(dibenzylideneacetone)palladium (0.341 g, 0.37
mmol, mol.%) and 1,1′-bis(diphenylphosphino)
a
solution of
4
ferrocene (0.827 g, 1.49 mmol, 16 mol.%) in anhydrous
DMF (18 mL) at room temperature, 4,5-dioctyl-1,2-
ditrifluoromethanesulfonyloxy)benzene (5.58 g, 9.32
mmol) was added under argon atmosphere via syringe.
The reaction mixture was stirred and heated until
the temperature stabilized at 62 °C. Once the desired
temperature was obtained, zinc cyanide (1.31 g, 11.2
mmol) was added in 16 equal portions over a period of
2 h whilst maintaining the temperature at 62–63 °C. After
addition, reaction was left stirring and heating at 62 °C for
a further 4 h. The resulting mixture was quenched in water
and the excess cyanide and spent catalyst filtered off using
vacuum filtration. The filtrate was washed with brine,
water and extracted with petroleum ether. The organics
were dried (Na2SO4), filtered and the solvent removed
under reduced pressure to give an orange oil. Addition
of ethanol caused excess dppf ligand to precipitate out
as an orange powder which was then filtered off. The
filtrate was evaporated to give a bright yellow oil. The oil
was purified by column chromatography over silica gel
(petroleum ether/ethyl acetate, 24: 1) to give the product
General procedure for the preparation of 4,5-dialkyl-
1,2-ditrifluoromethanesulfonyloxybenzenes
4,5-Dioctyl-1,2-ditrifluoromethanesulfonyloxy-
benzene. 4,5-Dioctyl-1,2-dihydroxybenzene (8.0 g, 20.9
mmol) and lutidine (8.36 mL, 7.69 g, 71.8 mmol) were
dissolved in 200 mL of distilled dichloromethane. The
mixture was cooled to -78 °C and trifluoromethanesul-
fonic anhydride (20.24 mL, 33.73 g, 119.5 mmol) was
added dropwise via syringe under an inert atmosphere.
After addition the light brown solution was left to warm
to room temperature and stirred overnight. The crude
product was washed with water (2 × 50 mL), brine,
extracted with dichloromethane, dried (Na2SO4) and
filtered. The solvent was removed under reduced pressure
and loaded onto a short silica gel column. The column
was eluted using petroleum ether and a single fluorescent
band was isolated from a brown/black baseline. The title
compound was recovered as a clear oil (10.2 g, 70%). IR
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 518–521

SYNTHESIS AND CHARACTERIZATION OF SOME OCTAALKYL SUBSTITUTED LEAD
519
as a yellow oil (3.1 g, 93%). IR (neat): n, cm-1 2233 (m,
Metal-free
2,3,9,10,16,17,23,24-octakis(hexyl)-
1
CN). H NMR (400 MHz, CDCl3): d, ppm 7.55 (2H,
phthalocyanine, p-6H2Pc. Following the general
procedure, the product was obtained as a blue solid (0.68
g, 35%). mp 246 °C (lit. 248–249 °C) [30, 39]. IR(neat): n,
cm-1 3277 (w, NH). MS (MALDI): isotopic cluster at m/z
1187.67 ([M]+, 100%). 1H NMR (400 MHz, d8-toluene):
d, ppm 9.35 (8H, s), 3.2–3.18 (16H, m) 2.2–2.15 (32H,
m), 1.65–1.63 (32H, m), 1.42–1.4 (24H, m), 0.35 (2H, s).
Anal. calcd. for C80H114N8: C, 80.89; H, 9.67; N, 9.38%.
Found C, 80.94; H, 9.71; N, 9.42%. UV-vis (toluene): l,
nm (log e) 703 (5.41).
s), 2.67 (4H, t, J = 7.9), 1.57 (4H, m), 1.27 (20H, m),
0.88 (6H, t, J = 6.9). 13C NMR (75 MHz, CDCl3): d, ppm
147.5, 134.1, 115.9, 112.9, 32.7, 31.9, 30.5, 29.6, 29.5,
29.3, 22.8, 21.2.
4,5-Dihexylphthalonitrile. Following the general
procedure, the product was recovered as a yellow oil
(1.53 g, 70%). IR (neat): n, cm-1 2232 (m, CN). 1H NMR
(400 MHz, CDCl3): d, ppm 7.52 (2H, s), 2.64 (4H, t, J =
7.9), 1.54 (4H, m), 1.21 (12H, m), 0.86 (6H, t, J = 6.8).
13C NMR (75 MHz, CDCl3): d, ppm 147.6, 134.2, 116.1,
113.0, 32.8, 31.8, 30.6, 29.4, 22.7, 14.2.
Metal-free
2,3,9,10,16,17,23,24-octakis(heptyl)-
phthalocyanine, p-7H2Pc. Following procedure, the title
compound was obtained as a blue solid (0.72 g, 37%). mp
267 °C. IR (neat): n, cm-1 3392 (w, NH). MS (MALDI):
4,5-Diheptylphthalonitrile. Following the general
procedure, the title compound was recovered as a yellow
1
1
oil (2.45 g, 71%). IR (neat): n, cm-1 2232 (m, CN). H
isotopic cluster at m/z 1300.07 ([M]+, 100%). H NMR
NMR (400 MHz, CDCl3): d, ppm 7.54 (2H, s), 2.64 (4H,
t, J = 7.9), 1.57 (4H, m), 1.28 (16H, m), 0.87 (6H, t, J
= 6.8). 13C NMR (75 MHz, CDCl3): d, ppm 147.6, 13.2,
116.0, 113.0, 32.8, 31.9, 30.6, 29.6, 29.2, 22.8, 14.3.
Anal. calcd. for C22H32N2: C, 81.43; H, 9.94; N, 8.63%.
Found C, 81.35; H, 9.83; N, 8.47%.
(400 MHz, d8-toluene): d, ppm 9.38 (8H, s), 3.31–3.28
(16H, m) 2.31–2.25 (32H, m), 1.66–1.63 (48H, m), 1.43–
1.4 (24H, m), 0.32 (2H, s). Anal. calcd. for C88H130N8: C,
81.30; H, 10.08; N, 8.62%. Found C, 81.40; H, 10.08; N,
8.55%. UV-vis (toluene): l, nm (log e) 703 (5.40).
Metal-free
2,3,9,10,16,17,23,24-octakis(nonyl)-
4,5-Dinonylphthalonitrile. Following the general
procedure, the title compound was recovered as a yellow
phthalocyanine, p-9H2Pc. Following procedure, the title
compound was obtained as a blue solid (0.60 g, 31%). mp
293 °C. IR (neat): n, cm-1 3289 (w, NH). MS (MALDI):
1
oil (2.45 g, 71%). IR (neat): n, cm-1 2231 (m, CN). H
1
NMR (400 MHz, CDCl3): d, ppm 7.53 (2H, s), 2.64 (4H,
t, J = 7.9), 1.54 (4H, m), 1.22 (24H, m), 0.85 (6H, t, J =
6.8). 13C NMR (75 MHz, CDCl3): d, ppm 147.5, 134.1,
116.0, 113.0, 32.8, 32.1, 30.6, 29.9, 29.7, 29.6, 29.5,
22.9, 14.3. Anal. calcd. for C26H40N2: C, 82.05; H, 10.59;
N, 7.36%. Found C, 81.83; H, 10.39; N, 7.22%.
isotopic cluster at m/z 1524.41 ([M]+, 100%). H NMR
(400 MHz, d8-toluene): d, ppm 9.4 (8H, s), 3.3–3.25
(16H, m) 2.3–2.25 (48H, m), 1.63–1.58 (64H, m), 1.4–
1.35 (24H, m), 0.32 (2H, s). Anal. calcd. for C104H162N8:
C, 81.94; H, 10.71; N, 7.35%. Found C, 81.89; H, 10.66;
N, 7.25%. UV-vis (toluene): l, nm (log e) 703 (5.38).
General procedure for the preparation of peripherally
substituted metal-free phthalocyanines
General procedure for the preparation of the lead
metalated derivatives
Metal-free 2,3,9,10,16,17,23,24-octakis(octyl)phth-
alocyanine, p-8H2Pc. 4,5-Dioctylphthalonitrile (1.0 g,
2.84 mmol) was dissolved in 1-pentanol (15.0 mL) with
stirring. The solution was set to reflux for 10 min at normal
atmosphere after which a small piece of lithium metal
(~10 mg) was added. The reaction mixture immediately
started turning dark green and was left refluxing for 1 h.
The resulting mixture was then left to cool and glacial
acetic acid (20.0 mL) was added after which the reaction
was reheated to reflux for a further 30 min. The metal-
free phthalocyanine precipitated from the solvent mixture
and was added to water (100 mL). The solid was filtered
using vacuum filtration and washed repeatedly with
methanol. A blue amorphous solid was recovered (0.62 g,
32%). mp 187 °C (lit. 185–187 °C) [30, 39]. IR (neat): n,
cm-1 3290 (w, NH). MS (MALDI): isotopic cluster at m/z
1412.21 ([M]+, 100%). 1H NMR (400 MHz, d8-toluene):
d, ppm 9.41 (8H, s), 3.26–3.2 (16H, m), 2.3–2.26 (40H,
m), 1.64–1.6 (56H, m), 1.42–1.38 (24H, m), 0.32 (2H, s).
Anal. calcd. for C96H146N8: C, 81.65; H, 10.42; N, 7.93%.
Found C, 81.69; H, 10.49; N, 7.94%. UV-vis (toluene): l,
nm (log e) 703 (5.34).
2,3,9,10,16,17,23,24-Octakis(octyl)phthalocyani-
nato lead, p-8PbPc. Metal-free 2,3,9,10,16,17,23,24-oct
akis(octyl) phthalocyanine (0.5 g, 0.35 mmol) was
dissolved together with lead(II) acetate trihydrate (0.20
g, 0.53 mmol) in 1-pentanol (20.0 mL). The reaction
was stirred and heated to reflux for 45 min after which
the color changed from blue/green to bright green. The
solution was poured onto methanol (~250 mL) and the
precipitate filtered. The recovered product was purified
using neutral alumina and diethyl ether as eluent.
Recrystallization of the main green fraction from DCM/
MeOH gave the title compound as a green amorphous
1
solid (0.42 g, 80%). mp 239 °C. H NMR (400 MHz,
d8-toluene): d, ppm 9.30 (8H, s), 2.70–2.95 (20H, m)
1.58–1.70 (20H, m), 1.20–1.37 (20H, m), 0.98 (52H,
m), 0.76 (24H, bt). MS (MALDI): isotopic cluster at m/z
1392.63 ([M]+, 100%). Anal. calcd. for C80H112N8Pb: C,
68.98; H, 8.10; N, 8.04%. Found C, 69.02; H, 8.18; N,
7.98%. UV-vis (toluene): l, nm (log e) 722 (5.46).
2,3,9,10,16,17,23,24-Octakis(hexyl)phthalocyaninato
lead, p-6PbPc. Following the general procedure, the
product was obtained as a fine green powder (0.40 g,
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 519–521

520
L.X. SOSA-VARGAS ET AL.
1
68%). mp 214 °C. H NMR (400 MHz, d8-toluene): d,
6.93%. Found C, 71.36; H, 9.07; N, 6.93%. UV-vis
(toluene): l, nm (log e) 748 (5.34).
ppm 8.83 (8H, s), 2.52–2.75 (20H, m) 1.37–1.49 (20H,
m), 1.13–1.18 (20H, m), 0.92–98 (20H, m), 0.58 (24H,
bt). MS (MALDI): isotopic cluster at m/z 1392.63 ([M]+,
100%). Anal. calcd. for C80H112N8Pb: C, 68.98; H, 8.10;
N, 8.04%. Found C, 69.02; H, 8.18; N, 7.98%. UV-vis
(toluene): l, nm (log e) 722 (5.45).
2,3,9,10,16,17,23,24-Octakis(heptyl)phthalocyani-
nato lead, p-7PbPc. Following the general procedure,
the title compound was obtained as a bright-green
1,4,8,11,15,18,22,25-Octakis(nonyl)phthalocyani-
nato lead, np-9PbPc. Following the general procedure
the title compound was obtained as a green solid (0.39 g,
67%). mp 34 °C. MS (MALDI): isotopic cluster at m/z
1728.97 ([M]+, 100%). 1H NMR (400 MHz, d8-toluene):
d, ppm 7.62 (8H, s), 4.55–4.80 (8H, m), 4.30–4.55 (8H,
m), 2.00–2.20 (16H, m), 1.40–1.60 (16H, m), 1.12–1.23
(16H, m), 0.76–1.12 (66H, m), 0.57 (24H, t). Anal. calcd.
for C104H162N8Pb: C, 72.22; H, 9.32; N, 6.48%. Found C,
72.39; H, 9.24; N, 6.39%. UV-vis (toluene): l, nm (log
e) 748 (5.35).
1
solid (0.40g, 72%). mp 239 °C. H NMR (400 MHz,
d8-toluene): d, ppm 9.18 (8H, s), 2.62–2.80 (20H, m)
1.37–1.49 (20H, m), 1.13–1.18 (20H, m), 0.98 (36H,
m), 0.76 (24H, bt). MS (MALDI): isotopic cluster at m/z
1504.78 ([M]+, 100%). Anal. calcd. for C88H128N8Pb: C,
70.22; H, 8.57; N, 7.44%. Found C, 70.21; H, 8.63; N,
7.34%. UV-vis (toluene): l, nm (log e) 722 (5.40).
2,3,9,10,16,17,23,24-Octakis(nonyl)phthalocyani-
nato lead, p-9PbPc. Following the general procedure, the
title compound was obtained as a bright green solid (0.42
g, 71%). mp 239 °C. 1H NMR (400 MHz, d8-toluene): d,
ppm 9.28 (8H, s), 2.78–2.95 (20H, m) 1.60–1.76 (20H,
m), 1.20–1.38 (20H, m), 0.92–1.20 (68H, m), 0.60 (24H,
bt). MS (MALDI): isotopic cluster at m/z 1729.30 ([M]+,
100%). Anal. calcd. for C104H160N8Pb: C, 72.22; H, 9.32;
N, 6.48%. Found C, 72.23; H, 9.28; N, 6.44%. UV-vis
(toluene): l, nm (log e) 722 (5.44).
CONCLUSION
A
series of peripherally and non-peripherally
octaalkyl substituted lead phthalocyanines have
been prepared and characterized with a view to the
investigation of the lability of the lead ion in an acidic
environment. The conversion of the lead metallated
derivatives into their metal-free analogs as solutions in
d8-toluene containing d4-acetic acid has been monitored
1
using H NMR spectrometry. From the data obtained
using a specific set of conditions, we can assert that the
position of the substituents on the ligand has a marked
effect on the rate of demetalation with the peripherally
substituted derivatives showing greater lability of the
lead ion compared to the non-peripherally substituted
compounds. Half-lives of the non-peripheral series
show demetalation occurs within 5–17 h, in contrast
with those of the peripherally substituted compounds
for which the half-lives were less than one hour. Lead
tetraphenyl porphyrin shows a demetalation rate broadly
comparable to that exhibited by the PbPc compounds of
the peripheral series.
1,4,8,11,15,18,22,25-Octakis(hexyl)phthalocyani-
nato lead, np-6PbPc. Following the general procedure,
the product was obtained as dark green needle-like
crystals (0.54 g, 88%) [MS (MALDI): isotopic cluster
at m/z 1391.97 ([M]+, 100%). H NMR (400 MHz,
1
d8-toluene): d, ppm 7.58 (8H, s), 4.50–4.70 (8H, m),
4.20–4.40 (8H, m), 1.90–2.10 (16H, m), 1.30–1.50 (16H,
m), 0.80–1.20 (32H, dm), 0.50 (24H, t). UV-vis (toluene):
l, nm (log e) 748 (5.35).
1,4,8,11,15,18,22,25-Octakis(heptyl)phthalocyani-
nato lead, np-7PbPc. Following the general procedure,
the title compound was obtained as bright-green fine
crystals (0.45 g, 78%). mp 105 °C. MS (MALDI):
Further properties of the PbPc derivatives that have
been investigated include the mesophase behavior
of the compounds and it is found that only those of
the p-PbPc series exhibit mesophase behavior. X-ray
crystal structures of the isomeric octa-octyl PbPcs have
also been reported and show markedly different core
conformations.
1
isotopic cluster at m/z 1505.27 ([M]+, 100%). H NMR
(400 MHz, d8-toluene): d, ppm 7.89 (8H, s), 4.66–4.50
(8H, m), 4.34–4.50 (8H, m), 2.00–2.20 (16H, m), 1.43–
1.62 (16H, m), 1.26–1.42 (16H, m), 1.15–1.31 (32H,
t), 0.75–0.85 (24H, t). Anal. calcd. for C88H128N8Pb: C,
70.22; H, 8.57; N, 7.44%. Found C, 70.19; H, 8.57; N,
7.42%. UV-vis (toluene): l, nm (log e) 748 (5.37).
1,4,8,11,15,18,22,25-Octakis(octyl)phthalocyani-
nato lead, np-8PbPc. Following the general procedure,
the title compound was obtained as green thread-like
crystals (0.44 g, 76%). mp 24 °C. MS (MALDI): isotopic
cluster at m/z 1616.49 ([M]+, 100%). 1H NMR (400 MHz,
d8-toluene): d,ppm 7.90 (8H, s), 4.65–4.50 (8H, m) 4.35–
4.50 (8H, m), 2.00–2.20 (16H, m), 1.42–1.61 (24H, m),
1.25–1.40 (16H, m), 1.12–1.32 (40H, m), 0.78 (24H,
t). Anal. calcd. for C96H144N8Pb: C, 71.29; H, 8.97; N,
Acknowledgements
We thank CONACYT, Mexico, and UEA for funding
(LXS-V). MJC gratefully thanks the Leverhulme
Foundation for the award of a Leverhulme Emeritus
Fellowship. SJC and GJT thank the EPSRC for funding.
Supporting information
Crystallographic data have been deposited at the
Cambridge Data Centre (CCDC) under deposition Nos.
CCDC 931006 [peripheral 2,3,9,10,16,17,23,24-octakis-
(octyl)phthalocyaninato lead(II)] and CCDC 931007
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 520–521

SYNTHESIS AND CHARACTERIZATION OF SOME OCTAALKYL SUBSTITUTED LEAD
521
[non-peripheral 1,4,8,11,15,18,22,25-octakis(octyl)phtha-
19. Ukei K. Acta Crystallogr. B 1973; 29: 2290–2292.
20. Burnham PM, Chambrier I, Hughes DL, Isare B,
Poynter RJ, Powell AK and Cook MJ. J. Porphyrins
Phthalocyanines 2006; 10: 1202–1211.
21. Burnham PM, Cook MJ, Gerrard LA, Heeney MJ
and Hughes DL. Chem. Comm. 2003; 2064–2065.
22. Kobayashi N, Fukuda T, Ueno K and Ogino H.
J. Am. Chem. Soc. 2001; 123: 10740–10741.
23. Barrett PA, Dent CE and Linstead RP. J. Chem. Soc.
1936; 1719–1936.
24. Collins RA, Strickland KR, Jeffery MJ, Davidson K
and Jones TA. Mater. Lett. 1990; 10: 170–174.
25. Mohan Kumar TM and Achar BN. J. Phys. Chem.
Solids 2006; 67: 2282–2288.
26. Sperl A, Kröger J and Berndt R. J. Am. Chem. Soc.
2011; 133: 11007–11009.
locyaninato lead(II)]. Copies can be obtained on request,
free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.
html or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
+44 1223-336-033 or email: deposit@ccdc.cam.ac.uk).
REFERENCES
1. Wright JD. Prog. Surf. Sci. 1989; 31: 1–60.
2. Wilson A, Rigby GP, Wright JD, Thorpe SC, Terui
T and Maruyama Y. J. Mater. Chem. 1992; 2:
303–308.
3. Mockert H, Schmeisser D and Goepel W. Sens.
Actuators 1989; 19: 159–176.
4. SadaokaY, Goepel W, Suhr B and RagerA. J. Mater.
Sci. Lett. 1990; 9: 1481–1483.
5. Sadaoka Y, Jones TA and Goepel W. Sens. Actua-
tors, B 1990; 1: 148–153.
6. Schoch KF and Temofonte TA. Thin Solid Films
1988; 165: 83–89.
7. Wiemhoefer HD, Schmeisser D and Goepel W.
Solid State Ionics 1990; 40–41: 421–427.
8. Martin M, Andre JJ and Simon J. Nouv. J. Chim.
1981; 5: 485–490.
9. Sharma GD, Choudhary VS and Roy MS. Sol.
Energ. Mat. Sol. C. 2007; 91: 1087–1096.
10. Mukherjee B, Ray AK, Sharma AK, Cook MJ
and Chambrier I. J. Appl. Phys. 2008; 103:
074507/1-074507/4.
27. McKeown NB, Chambrier I and Cook MJ. J. Chem.
Soc., Perkin Trans. 1 1990; 1169–1177.
28. Nesi R, Turchi S, Giomi D and Corsi C. Tetrahe-
dron 1998; 54: 10851–10856.
29. Terekhov DS, Nolan KJM, McArthur CR and
Leznoff CC. J. Org. Chem. 1996; 61: 3034–3040.
30. Drechsler
1207–1208.
U and Hanack M. Synlett 1998;
31. Ellis GP and Romney-Alexander TM. Chem. Rev.
1987; 87: 779–794.
32. Wöhrle D, Eskes M, Shigehara K and Yamada A.
Synthesis 1993; 2: 194–196.
33. Aranyos V, Castano AM and Grennberg H. Acta.
Chem. Scand. 1999; 53: 714–720.
34. Muto T, Temma T, Kimura M, Hanabusa K and
Shirai H. Chem. Comm. 2000; 17: 1649–1650.
35. Cherodian AS, Davies AN, Richardson RM, Cook
MJ, McKeown NB, Thomson AJ, Feijoo J, Ungar G
and Harrison KJ. Mol. Cryst. Liq. Cryst. 1991; 196:
103–114.
36. Cook MJ, Chambrier I, Cracknell SJ, Mayes DA
and Russell DA. Photochem. Photobiol. 1995; 62:
542–545.
37. Cook MJ and Chambrier I. J. Porphyrins Phthalo-
cyanines 2011; 15: 149–173.
38. Coles SJ and Gale PA. Chem. Sci. 2012; 30:
683–689.
11. Shafai TS. Thin Solid Films 2008; 517: 1200–1203.
12. Shafai TS and Gould RD. Int. J. Electron. 1992; 73:
1043–1045.
13. Valkova LA, Zyablov SV, Erokhin VV and Koif-
man OI. J. Porphyrins Phthalocyanines 2010; 14:
513–522.
14. O’Flaherty SM, Hold SV, Cook MJ, Torres T, ChenY,
Hanack M and Blau WJ. Adv. Mater. 2003; 15: 19–32.
15. Auger A, Blau WJ, Burnham PM, Chambrier I,
Cook MJ, Isare B, Nekelson F and O’Flaherty SM.
J. Mater. Chem. 2003; 13: 1042–1047.
16. Piechocki C, Simon J, Skoulios A, Guillon D and
Weber P. J. Am. Chem. Soc. 1982; 104: 5245–5247.
17. Weber P, Guillon D and Skoulios A. J. Phys. Chem.
1987; 91: 2242–2243.
39. Hanack M, Beck A and Lehmann H. Synthesis
1987; 8: 703–705.
18. Waclawek W and Zabkowska M. Acta Phys. Hung.
1980; 49: 275–279.
Copyright © 2013 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2013; 17: 521–521