The self-ordering properties of novel phthalocyanines with out-of-plane alkyl substituents

Article abstract of DOI:10.1002/chem.200600697

Two novel homologous series of phthalocyanines were prepared from 2,2-dialkylindane and 2,2-dialkyl-1,3-benzodioxole precursors. It was anticipated that attaching alkyl chains to five-membered rings, fused to the peripheral sites of the phthalocyanine ring, would result in the adoption of an out-of-plane configuration and thereby discourage cofacial aggregation, to provide an analogy with picket-fence porphyrins. This strategy proved partially successful. Some members of the series of phthalocyanines derived from 2,2-dialkyl-1,3-benzodioxoles, in which the alkyl chains are linked to the phthalocyanine via a cyclic ketal, form spin-coated thin films in which the phthalocyanine cores are perfectly isolated. This behaviour is associated with the formation of a disordered crystal that appears as a mesophase in the thermal profile of these materials. However, the phthalocyanines derived from 2,2-dialkylindanes display a columnar mesophase over a wide temperature range, with some liquid crystalline derivatives at ambient temperature. A single-crystal X-ray diffraction structure of the octahexyl derivative of this series shows how the columnar assembly accommodates the out-of-plane alkyl chains by tilting the macrocyclic plane of the phthalocyanine components with respect to the axis of the column. This study helps to emphasise the importance of both the steric and electronic effects of substituents on the packing behaviour of phthalocyanines in the condensed phase, and especially the role of electron-donating oxygen atoms directly attached to the ring.

Full text of DOI:10.1002/chem.200600697

DOI: 10.1002/chem.200600697
The Self-Ordering Properties of Novel Phthalocyanines with Out-of-Plane
Alkyl Substituents
Neil B. McKeown,*[a] Madeleine Helliwell,[b] Bashir M. Hassan,[b] David Hayhurst,[b]
Hong Li,[b] Neil Thompson,[b] and Simon J. Teat[c]
Abstract: Two novel homologous series
of phthalocyanines were prepared from
2,2-dialkylindane and 2,2-dialkyl-1,3-
benzodioxole precursors. It was antici-
pated that attaching alkyl chains to
five-membered rings, fused to the pe-
ripheral sites of the phthalocyanine
ring, would result in the adoption of an
out-of-plane configuration and thereby
discourage cofacial aggregation, to pro-
vide an analogy with picket-fence por-
phyrins. This strategy proved partially
successful. Some members of the series
of phthalocyanines derived from 2,2-di-
alkyl-1,3-benzodioxoles, in which the
alkyl chains are linked to the phthalo-
cyanine via a cyclic ketal, form spin-
coated thin films in which the phthalo-
cyanine cores are perfectly isolated.
This behaviour is associated with the
formation of a disordered crystal that
appears as a mesophase in the thermal
profile of these materials. However,
the phthalocyanines derived from 2,2-
rivatives at ambient temperature. A
single-crystal X-ray diffraction struc-
ture of the octahexyl derivative of this
series shows how the columnar assem-
bly accommodates the out-of-plane
alkyl chains by tilting the macrocyclic
plane of the phthalocyanine compo-
nents with respect to the axis of the
column. This study helps to emphasise
the importance of both the steric and
electronic effects of substituents on the
packing behaviour of phthalocyanines
in the condensed phase, and especially
the role of electron-donating oxygen
atoms directly attached to the ring.
dialkylindanes display
mesophase over a wide temperature
range, with some liquid crystalline de-
a
columnar
AHCTREUNG
Keywords: dyes/pigments
crystals phthalocyanines · self-
assembly · thin films
· liquid
·
Introduction
carriers[4] and exciton-transport materials,[5] optical data stor-
age (as the laser absorption layer within recordable discs),[6]
photodynamic cancer therapy,[7] solar energy conversion,[8]
catalysis[9] and as the active component of gas sensors.[10] For
most of these applications, not only are the molecular prop-
erties of importance (e.g., lmax) but also the way in which
these properties are influenced by intermolecular interac-
tions. Hence, the packing of the disc-shaped macrocycles in
the condensed state needs to be understood and controlled.
By placing long alkyl (Pc series 1)[11,12] or alkoxy (Pc
series 2)[11,13] side chains on the peripheral positions
(2,3,9,10,16,17,23,24) of the phthalocyanine ring the solubili-
ty is enhanced and leads to liquid-crystalline behaviour in
which the aromatic rings assemble into columnar stacks. De-
rivatives with long alkyl side chains attached to the nonpe-
Phthalocyanine (Pc) and its derivatives constitute one of the
most studied classes of organic functional materials.[1] In ad-
dition to their widespread use as blue and green colourants,
phthalocyanines are of increasing interest for applications in
nonlinear optics (including optical limitation),[2] xerography
(as photoconductors),[3] liquid-crystalline electronic charge
[a] Prof. N. B. McKeown
School of Chemistry, Cardiff University
Cardiff, CF10 3AT (UK)
Fax : (+44)2920-874-030
E-mail: mckeownnb@cardiff.ac.uk
[b] Dr. M. Helliwell, Dr. B. M. Hassan, Dr. D. Hayhurst, Dr. H. Li,
Dr. N. Thompson
A
liquid crystals (Pc series 3).[14,15] However, nonperipheral
substitution with alkoxy side chains (Pc series 4)[16] does not
result in mesogenic phthalocyanines and aggregation of the
aromatic cores is suppressed in the solid state.[17] Placing
alkoxy groups at the nonperipheral sites also results in a
shift of the main absorption band in the visible spectrum
School of Chemistry, University of Manchester
Manchester, M13 9PL (UK)
[c] Dr. S. J. Teat
CCLRC Daresbury Laboratory, Daresbury
Warrington, Cheshire, WA4 4AD (UK)
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
228
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Chem. Eur. J. 2007, 13, 228 – 234

FULL PAPER
yield by following a literature
method.[23] However, the re-
duction of the 2,2-dialkyl-1-in-
danone was sluggish under a
variety of conditions (Wolf–
Kishner, palladium-catalysed
hydrogenation),
presumably
owing to steric hindrance at
the crowded ketone. Ultimate-
ly, the best results were ob-
tained from ionic reduction
using triethylsilane dissolved in
trifluoroacetic acid (TFA).[24]
In contrast, owing to the com-
mercial availability of dialkyl-
ketones, the 2,2-dialkyl-1,3-
benzodioxole precursors to Pc
series 6 were prepared much
(the Q-band) into the near-IR region so that the phthalocya-
nines do not display their characteristic strong blue or green
colour. In contrast, self-assembly into columnar aggregates
broadens and blueshifts the Q-band as a result of exciton in-
teractions.[18,19] Therefore, in order to obtain solid phthalo-
cyanines that demonstrate similar light absorption character-
istics to those of their dilute solutions, it was an attractive
objective to place alkyl side chains on the macrocycle in
such a way as to strongly disfavour aggregation but without
perturbing the basic phthalocyanine chromophore.[20,21] The
chosen strategy was to attach the alkyl chains to five-mem-
bered rings fused to the peripheral sites of the phthalocya-
nine so that the chains would project out of the molecular
plane of the macrocycle and enforce separation through
mutual steric interference. It was anticipated that the target
phthalocyanines, derived from 2,2-dialkylindanes (Pc series
5) and cyclic ketals (Pc series 6), would possess similar char-
acteristics to the well-known picket-fence porphyrins in
which substituents prohibit aggregation of the macrocycle
and protect functionality.[22]
more readily by the simple ketalisation of catechol.[25]
On a laboratory scale, the synthesis of metal-free phthalo-
cyanines is best achieved by the cyclotetramerisation of a
phthalonitrile precursor by using, for example, a refluxing
mixture of lithium pentyloxide in n-pentanol.[26] The re-
quired phthalonitrile precursors to Pc series 5 and 6 were
prepared from the 2,2-dialkylindane and 2,2-dialkyl-1,3-ben-
zodioxole intermediates, respectively, by bromination fol-
lowed by substitution of the bromide by nitrile by using the
Rosenmund–von Braun reaction (Scheme 1).[11] Bromination
of the 2,2-dialkyl-1,3-benzodioxoles using N-bromosuccin-
A
cleavage of the cyclic ketal, which accompanied the attempt-
ed reaction with molecular bromine. Generally, members of
Pc series 6 were isolated in greater yields (10–25%) than
those of 5 (3–10%) from the phthalocyanine-forming reac-
tion as a result of their greater tendency to recrystallise
(from acetone), which facilitated efficient purification.
Molecular properties: All of the phthalocyanines in series 5
and 6 are highly soluble in common organic solvents (e.g.,
hexane, toluene, dichloromethane, THF) at room tempera-
ture, whereas the phthalocyanines of series 1 and 2, in which
the alkyl chains are directly linked to the peripheral sites,
are only sparingly soluble in the same solvents at room tem-
perature. This enhanced solubility is similar to that dis-
played by the members of Pc series 3 and 4. Also, in con-
Results
Synthesis: The synthetic route to the 2,2-dialkylindanes re-
quired for Pc series 5 proved to be challenging. Base-cata-
lysed dialkylation of 1-indanone was achieved in moderate
Scheme 1. The synthesis of phthalocyanine series 5 and 6. Reagents and conditions: a) RBr, tBuOK, toluene, 808C, 4 h; b) Et3SiH, TFA, 808C, 48 h;
c) Br2, Fe, I2, CH2Cl2, 2 08C, 2h; d) CuCN, DMF, 140 8C, 18 h; e) Li, 1-pentanol, reflux, 10 h; f) catechol, p-TSA, toluene, reflux, 48 h; g) NBS, DMF,
208C, 48 h.
Chem. Eur. J. 2007, 13, 228 – 234
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229

N. B. McKeown et al.
trast to Pc series 1 and 2, the effects of aggregation (i.e.,
spectral peak broadening and shifts) are not observed from
1H NMR and UV-visible absorption spectra for solutions of
up to 1”10À4 molmLÀ3 concentrations. The UV-visible ab-
sorption spectra of Pc series 5 and 6 are very similar to
those of Pc series 1 and 2, respectively, with the colour (blue
for Pc series 1 and 5, green for 2 and 6) being determined
by the element (O or C) attached directly to the peripheral
site. The green colour of Pc series 1 and 5 is a result of the
strong absorption bands in both the red (l=690, 650 nm)
and blue (l=430 nm) regions of the spectrum.
One remarkable characteristic of the members of Pc
series 6 is the resistance of their ketal groups towards hy-
drolysis. Generally, cyclic ketals are hydrolysed in dilute
aqueous acid. However, even the application of strongly
acidic conditions over prolonged periods does not result in
removal of the cyclic ketals. Indeed, the hydrolytic destruc-
tion of the phthalocyanine core takes place prior to ketal re-
moval. This behaviour is related to the well-documented ba-
sicity of the phthalocyanine ring, which is protonated in
preference to the ketal oxygen atoms. Similar hydrolysis-re-
sistant ketals that contain basic functional groups are
known.[28]
Figure 1. UV-visible absorption spectra of spin-coated films of a) Pc 5(C9),
b) Pc 6(C12) and c) Pc 6(C9) after annealing at 1508C.
A
the alkyl chains was expected to hinder cofacial self-associa-
tion. A single-crystal X-ray diffraction (XRD) study of Pc
5(C6) gave a clear insight into the columnar molecular ar-
rangement formed by this series (Figure 2). Of the eight
hexyl chains, five are oriented out of the plane of the phtha-
locyanine core, as intended. However, the out-of-plane
chains do not disrupt the columnar self-association of the
phthalocyanine cores owing to the severe tilt (458) of the
macrocyclic plane of the molecules relative to the stacking
direction and the 308 twist of each molecule relative to its
neighbour, so that there is a repeat unit of three phthalocya-
nines along the stack. Similar tilted stacks are inferred from
the results of powder XRD studies of the hexagonal colum-
nar mesophase displayed by members of Pc series 1.[30]
Condensed-state properties: Pc series 5 and 6 display very
different condensed-phase properties. Thermal analysis of
Pc series 5(C6–C12) by using polarising optical microscopy
A
(POM) and differential scanning calorimetry (DSC) re-
vealed that each derivative forms a birefringent mesophase
over a very large temperature range and that the longer-
chained derivatives (C9–C12) are liquid crystals at room tem-
perature (Table 1). The observed focal conic optical texture
can be unambiguously assigned to the hexagonal columnar
mesophase that is commonly encountered in the thermal be-
haviour of alkylated phthalocyanines (e.g., Pc series 1–
3).[1,11–15,17,29] The UV-visible absorption spectrum of a spin-
coated film of Pc 5(C9) displays a lmax of 620 nm (Figure 1),
which is consistent with a blueshifted Q-band owing to the
formation of an extended cofacial stack of phthalocyanine
molecules, as would be expected for a columnar meso-
phase.[19,21] In the context of the objectives of the molecular
design, it is perhaps surprising that columnar self-assembly
is demonstrated for these derivatives, as the arrangement of
As expected, short-chained Pc 6(C2) forms a microcrystal-
line solid, which does not undergo any thermal phase transi-
tion below its decomposition temperature (ꢀ3508C). POM
and DSC analyses show that long-chained Pcs 6(C11 and C12)
melt from waxy malleable solids into fluid isotropic liquids
at 87 and 498C, respectively. The medium-length Pcs 6(C5–
A
C10) are highly unusual in that they form large, square crys-
tals (up to 5”5”0.1 mm), which on heating, melt firstly into
a highly viscous mesophase and then undergo a second tran-
sition to the fluid isotropic
liquid (Table 1). Neither the
Table 1. The thermal transition temperatures (in 8C) for members of phthalocyanine series 1–6 as measured
by using polarising microscopy and differential thermal calorimetry.[a,b]
solid crystals nor the meso-
phase appear birefringent but,
on cooling the isotropic phase
below the clearing point, air
bubbles trapped within the
thin film of the melt become
polygonal. Despite the size and
apparent quality of the large
square crystals, and many at-
tempts, X-ray crystallographic
Series 1[12]
Series 2[13]
Series 3[14]
Series 4[16]
Series 5
Series 6
K–Colh Colh–I K–Colh Colh–I K–Colh Colh–I
K–I
K–Colh Colh–I K–Mx Mx–I
C6
C7
C8
C9
C10
C11
C12
250
–
186
–
163
–
120
363
–
325
–
283
–
253
119
104
94
101
94
>350
>350
>350
>350
345
161
113
85
103
78
–
171
163
15266
14250
133
–
86
77
75
240
160
>350
>350
145
310
280
177
150
199
139
109
K-I
K-I
325
240
350
<0
<0
<0
<0
172
123
87
51
–
53
83
83
334
309
240
185
–
–
49
[a] K=crystal; Colh =hexagonal columnar liquid crystal; I=isotropic liquid; Mx =unknown mesophase—prob-
ably a disordered crystal. [b] Thermal degradation occurs above 3508C. Thermal transitions were not measured
below 08C.
analysis failed as
a conse-
quence of poor diffraction as-
230
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Chem. Eur. J. 2007, 13, 228 – 234

Self-Ordering Phthalocyanines
FULL PAPER
the peripheral alkyl chains to lie out of the plane of the Pc
ring, whereas the relatively small alkoxy linking groups of
Pc Series 2 allows the side chains to sit comfortably in the
plane of the macrocycle.[13] This conformational difference is
consistent with the lower clearing temperatures (> 508C)
for Pc series 1 relative to those of series 2 (Table 1 and
Figure 3) and has been held responsible for the tilted ar-
rangement of the phthalocyanines within the columnar stack
of the mesophases formed by Pc series 1.
Figure 2. XRD structure from a single crystal of Pc 5(C6): a) the tilted ar-
rangement of phthalocyanines relative to the axis of the columnar stack
(x axis of crystal) that facilitates the accommodation of the out-of-plane
alkyl chains; b) a view down the axis of the columnar stack, with alkyl
chains removed for clarity, showing the trimeric repeat unit that forms
the stacks.
Figure 3. The transition temperatures at which the isotropic liquid is
formed on heating Pc series 1–6 (i.e., clearing temperatures for Pc series
1–3, 5 and Pc 6(C6–C10) and melting points for Pc series 4 and Pc 6(C11
R
~
&
^
*
*
and C12)). Pc series: 1 ( ); 2 ( ); 3 ( ); 4 ( ); 5 (&); 6 ( ).
sociated with the thin axis of the crystal. However, some in-
formation on packing within the crystal of the Pc series 6-
(C5–C10) is obtained from analysis of the diagnostic Q-band
For Pc series 3 and 4, the strongest steric interactions in-
volving the nonperipheral side chains are between the
chains on neighbouring benzo moieties. These interactions
result in the displacement of the side chains from the plane
of the Pc ring. This effect is clearly evident in the crystal
structures of members of these series[31] and explains the
much lower clearing temperatures (>1508C) of Pc series 3
relative to those of series 1 (Figure 3). The members of Pc
series 4 melt directly from the crystal to the isotropic liquid
at low temperatures (45–858C) without the formation of a
columnar mesophase.[16] This behaviour has been ascribed to
the combined effect of the mutual steric interference of the
nonperipheral side chain and the modulation of the attrac-
tive p--p intermolecular interactions as a result of the elec-
tron-donating effect of the eight oxygen atoms directly at-
tached to the macrocycle.[1,17,21,32]
of the UV-visible absorption spectra obtained from spin-
coated films (Figure 1). Spectra derived from as-deposited
films indicate that the film contains a mixture of isolated
molecules (lmax =690 and 655 nm) together with cofacial
dimers (lmax =635 nm). However, films heated above the ini-
tial melting point of the phthalocyanine display spectra that
are identical to those of isolated molecules obtained from a
dilute solution (lmax =690 and 655 nm). Therefore, it appears
that the phthalocyanines adopt an isolated arrangement in
the crystal form of these materials. Similar analysis of the
low-melting, long-chained members of series Pc 6(C11 and
C12) give spectra characteristic for discrete cofacial dimers
(lmax =635 nm). Therefore, the isolated solid form of Pc
series 6
A
Based on the clearing temperatures of the hexagonal col-
umnar mesophase of the members of series 1, 3 and 5
(Figure 3), it can be concluded that the strategy of reducing
phthalocyanine cofacial association by attaching alkyl chains
to a five-membered carbon ring fused to the periphery of
the macrocycle (series 5) is no more efficient than the direct
attachment of the chains at the peripheral sites (series 1).
Indeed, by placing the alkyl chains at the nonperipheral
sites (series 3), a much greater destabilising effect on the
thermal stability of the columnar mesophase appears to be
induced. However, crystallisation of the mesophase is sup-
pressed in Pc series 5 so that longer-chained members dis-
manifestation of the mesophase.
This work confirms that the occurrence and stability of col-
umnar self-assembled alkyl-substituted phthalocyanines is
influenced strongly by the manner in which the alkyl chains
are connected to the macrocycle. Molecular modelling cal-
culations suggest that the mutual steric interactions of the
adjacent methylene linking groups of Pc series 1 encourage
Chem. Eur. J. 2007, 13, 228 – 234
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231

N. B. McKeown et al.
play a stable columnar mesophase at room temperature,
which may be a useful property (Table 1).
with the formation of a disordered crystal that appears as a
mesophase in the thermal profile of these materials. Howev-
er, similar phthalocyanines derived from 2,3-dialkylindanes
(Pc series 5) form columnar liquid crystals of similar thermal
stability to derivatives in which the alkyl chains are linked
directly to the peripheral sites of the ring. A single-crystal
XRD structure shows how the columnar assembly formed
by these derivatives accommodates the alkyl chains by dras-
tically tilting the macrocyclic plane of the phthalocyanine
components with respect to the axis of the column. This
study helps to emphasise the importance of both steric and
electronic effects of substituents on the packing behaviour
of phthalocyanines in the condensed phase.
A similar comparison of the phthalocyanines with oxygen
atoms directly attached to the ring (Pc series 2, 4 and 6)
shows that members of novel Pc series 6 do not form colum-
nar assemblies, which is in stark contrast to the behaviour of
series 2 but mirrors the behaviour of series 4. For both
series 4 and 6, the out-of-plane configuration of the alkyl
chains must combine with the electronic effect of the
oxygen atoms, linked directly to the macrocycle, to discour-
age cofacial association. The unexpected thermal behaviour
of series 6(C6–C10) appears to be related to the ease of for-
G
mation of a disordered crystal in which the out-of-plane
alkyl chains act as efficient spacers between the neighbour-
ing macrocycles. Based upon the distinct square-shaped crys-
tals formed by these compounds, it is tempting to suggest a
planar tetragonal arrangement of the phthalocyanines sepa-
rated by a layer of disordered alkyl chains with only loose
structural correlation between the planar arrays. The differ-
ence between the crystalline and mesophase state of these
phthalocyanines may be related only to the mobility of the
alkyl chains (i.e., the mesophase is a disordered crystal). It
is notable that the change in enthalpy for the transition
from crystal to mesophase is only a few kJmolÀ1 for Pc
series 6, whereas for Pc series 2 the crystal to columnar
Experimental Section
1H NMR spectra (300 MHz) were recorded by using an Inovo 300 spec-
trometer. IR spectra were recorded on an ATI Mattson Genesis Series
FTIR instrument (KBr/Germanium beam splitter). Elemental analyses
were obtained by using a Carlo Erba Instruments CHNS-O EA 108 Ele-
mental Analyser. MALDI mass spectra were obtained by using a Micro-
Mass Tofspec 2E spectrometer. UV-visible spectra were recorded on a
Shimadzu UV-260 spectrometer. All solvents were dried and purified as
described in ref. [33]. All materials were placed under vacuum at 1008C
for 18 h as the final step of purification. Intermediates that gave viscous
oils were used in the next step without purification—details of their syn-
thesis are given in the Supporting Information.
mesophase transition is associated with a much larger en-
E
thalpy change (70–100 kJmolÀ1) consistent with the melting
of highly ordered alkyl chains.[13] Further structural charac-
terisation of the highly disordered crystals formed by Pc
series 6 is required.
Pc 5(C12): Lithium metal (0.02g, 7 mmol) was added to a stirred solution
T
of 5,6-dicyano-2,2-dodecylindane (0.5 mg, 0.1 mmol) in 1-pentanol
(2mL) at 120 8C under nitrogen. The mixture was stirred at reflux for
10 h. On cooling, acetic acid (2mL) was added and the reaction was stir-
red at room temperature for 1 h. Methanol (20 mL) was added, the mix-
ture was stirred for a further 30 min and the solid material was collected
by filtration. The product was purified by means of column chromatogra-
phy using a silica gel column with CH2Cl2/hexane as eluent and by recrys-
tallisation from acetone to give a blue waxy solid (35 mg, 7%). M.p
(mesophase–isotropic) 1858C; 1H NMR (500 MHz, CDCl3, 608C): d=
À2.05 (brs, 2H), 0.93 (t, 24H), 1.17–1.60 (m, 160H), 1.75 (brm, 16H),
3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis (CH2Cl2): lmax =700, 660, 638,
580, 340, 285 nm; MALDI MS: m/z: 2 02 3M[ ++H+]; elemental analysis
calcd (%) for C140H226N8: C 83.19, H 11.27, N 5.54; found: C 83.11, H
11.90, N 5.47.
An interesting observation can be made regarding the
transition temperature at which each phthalocyanine forms
an isotropic melt (Figure 3). For each pair of series in which
the alkyl side chains are attached to the phthalocyanine at
the same sites (i.e., series 1 and 2, series 3 and 4, series 5
and 6) and which, therefore, differ only in the group directly
attached to the ring (i.e., O or CH2), the transition tempera-
ture trend lines are parallel. Each additional methylene unit
on the alkyl chains causes an average reduction in the tran-
sition temperature of 188C for peripheral substitution
(series 1 and 2), 98C for nonperipheral substitution (series 3
and 4) and 428C for linking the alkyl chain to the phthalo-
cyanine via a fused ring (series 5 and 6). The much greater
destabilising effect on phthalocyanine self-assembly per ad-
ditional methylene unit for series 5 and 6 is consistent with
an out-of-plane conformation of the alkyl chains.
The following phthalocyanines were prepared from the appropriate 5,6-
dicyano-2,2-dialkylindanes by using a similar procedure.
1
Pc 5(C6): 4% yield; m.p (crystal–mesophase) 2508C; H NMR (500 MHz,
CDCl3, 608C): d=0.93 (t, 24H), 1.0–1.50 (m, 64H), 1.75 (brm, 16H),
3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis (CH2Cl2): lmax =700, 660, 638,
580, 340, 285 nm; MALDI MS: m/z: 1349 [M++H+]; elemental analysis
calcd (%) for C98H130N8: C 81.87, H 9.72, N 8.31; found: C 81.00, H 9.94,
N 7.71.
Crystal data for Pc 5(C6): Data were collected at 150 K using synchrotron
radiation at Daresbury SRS, UK (Station 9.8), on a Siemens SMART
CCD diffractometer (l=0.6934 Š) and the structure was solved by direct
methods. All calculations were carried out by using the SHELXTL pack-
Conclusion
age.[34] Crystal size 0.42”0.12”0.01 mm; triclinic; space group P1, a=
¯
The strategy to discourage cofacial aggregation of the phtha-
locyanine macrocycle by attaching alkyl side chains to a
five-membered ring fused to the peripheral sites of the mac-
1.57306(16), b=2.0621(3), c=2.1527(4) nm; a=62.462(10), b=
82.358(17), g=86.470(13)8; V=6.1367(15) nm3; Z=3;
m
ACHTREUNG
=
0.0817); 12988 reflections with I >2s(I); R=0.1194 and wR2=0.3071
(observed data); R=0.1911 and wR2=0.3353 (all data). The asymmetric
unit consists of one whole molecule, together with a half molecule from
which the complete molecule is generated by inversion. There is disorder
in some of the hexyl chains, such that some atoms are disordered over
rocycle proved partially successful. Pc series 6(C6–C10),
A
where the alkyl chains are linked to the phthalocyanine via
a cyclic ketal, form thin-films in which the phthalocyanine
cores are perfectly isolated. This behaviour is associated
232
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Chem. Eur. J. 2007, 13, 228 – 234

Self-Ordering Phthalocyanines
FULL PAPER
two sites with occupancies constrained to sum to unity. Non-hydrogen
atoms were refined anisotropically, with restraints on the thermal motion
of the carbon atoms, except those that were disordered. Hydrogen atoms
were included in calculated positions. CCDC-607387 contains the supple-
mentary crystallographic data for this paper. These data can be obtained
free of charge from the Cambridge Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
MALDI MS: m/z: 1588 [M++H+]; elemental analysis calcd (%) for
C100H146N8O8: C 75.60, H 9.28, N 7.05; found: C 75.56, H 9.26, N 7.05.
Pc 6(C9): 22% yield; m.p. 1398C (crystal–mesophase), 1728C (meso-
1
phase-I); H NMR (500 MHz, CDCl3, 608C): d=À1.75 (brs, 2H), 0.90 (t,
24H), 1.40–1.45 (brm, 96H), 1.82 (brs, 16H), 2.30 (brs, 16H), 8.45 ppm
(s, 8H); UV/Vis (toluene): lmax =692, 651, 645, 595, 430, 350 nm;
MALDI MS: m/z (MALDI): 1811 [M++H+]; elemental analysis calcd
(%) for C108H162N8O8: C 76.28, H 9.60, N 6.59; found: C 76.49, H 9.71, N
6.75.
1
Pc 5(C7): 4% yield; m.p (crystal–mesophase) 1608C; H NMR (500 MHz,
CDCl3, 608C): d=0.93 (t, 24H), 1.0–1.55 (m, 80H), 1.75 (brm, 16H),
3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis (CH2Cl2): lmax =700, 660, 638,
580, 340, 285 nm; MALDI MS: m/z: 1461 [M++H+]; elemental analysis
calcd (%) for C100H146N8: C 82.25, H 10.08, N 7.67; found: C 81.93, H
9.91, N 7.22.
Pc 6(C10): 21% yield; m.p. 1098C (crystal–mesophase), 1238C (meso-
R
phase-I); 1H NMR(500 MHz, CDCl3, 608C): d=À1.45 (brs, 2H), 0.82 (t,
24H), 1.30–1.60 (m, 112H), 2.05 (brs, 16H), 2.36 (brs, 16H), 8.65 ppm (s,
8H); UV/Vis (toluene): lmax =691, 651, 645, 595, 430, 350 nm; MALDI
MS: m/z: 1700 [M++H+]; elemental analysis calcd (%) for C116H178N8O8:
Pc 5(C8): 10% yield; m.p (crystal–mesophase) 758C, (mesophase-isotrop-
ic) 3508C; 1H NMR (500 MHz, CDCl3, 608C): d=0.93 (t, 24H), 1.0–1.55
(m, 96H), 1.75 (brm, 16H), 3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis
(CH2Cl2): lmax =700, 660, 638, 580, 340, 285 nm; MALDI MS: m/z: 1573
[M++H+]; elemental analysis calcd (%) for C108H162N8: C 82.49, H 10.38,
N 7.13; found: C 81.99, H 10.28, N 6.92.
C 76.84, H 9.91, N 6.18; found: C 76.77, H 10.00, N 6.19.
1
Pc 6
A
À1.45 (brs, 2H), 0.81 (t, 24H), 1.25–1.60 (m, 112H), 2.06 (brs, 16H),
2.38 (brs, 16H), 8.65 ppm (s, 8H); UV/Vis (toluene): lmax =691, 651, 645,
595, 430, 350 nm; MALDI MS: m/z: 1825 [M++H+]; elemental analysis
calcd (%) for C124H194N8O8: C 77.35, H 10.17, N 5.82; found: C 77.45, H
Pc 5(C9): 3% yield; m.p. (mesophase-isotropic) 3108C; 1H NMR
(500 MHz, CDCl3, 608C): d=0.93 (t, 24H), 1.0–1.55 (m, 112H), 1.75
10.31, N 5.76.
1
Pc 6
A
(brm, 16H), 3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis (CH2Cl2): lmax
=
700, 660, 638, 580, 340, 285 nm; MALDI MS m/z: 1686 [M++H+]; ele-
mental analysis calcd (%) for C116H178N8: C 82.70, H 10.65, N 6.65;
found: C 82.44, H 10.68, N 6.36.
À1.46 (brs, 2H), 0.80 (t, 24H), 1.17–1.57 (m, 144H), 1.79 (brs, 16H),
2.25 (brs, 16H), 8.45 ppm (s, 8H); UV/Vis (toluene): lmax =692, 651, 638,
591, 428, 349 nm; MALDI MS: m/z: 2037 [M++H+]; elemental analysis
calcd (%) for C132H210N8O8: C 77.80, H 10.40, N 5.50; found: C 77.45, H
10.53, N 5.64.
Pc
5
(C10): 8% yield; m.p. (mesophase–isotropic) 2808C; 1H NMR
A
(500 MHz, CDCl3, 608C): d=0.93 (t, 24H), 1.0–1.55 (m, 128H), 1.75
(brm, 16H), 3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis (CH2Cl2): lmax
=
700, 660, 638, 580, 340, 285 nm; MALDI MS m/z: 1797 [M++H+]; ele-
mental analysis calcd (%) for C124H194N8: C 82.98, H 10.88, N 6.24;
found: C 82.39, H 10.65, N 6.65.
Acknowledgements
Pc
(500 MHz, CDCl3, 608C): d=0.93 (t, 24H), 1.0–1.55 (m, 144H), 1.75
(brm, 16H), 3.30 (brs, 16H), 8.60 ppm (s, 8H); UV/Vis (CH2Cl2): lmax
700, 660, 638, 580, 340, 285 nm; MALDI MS:
m/z: 1909 [M++H+]; ele-
5
A
This work was funded by the EPSRC.
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