The structures of several modified isoindolines, the building blocks of phthalocyanines

Article abstract of DOI:10.1142/S1088424613500107

This report presents the single crystal X-ray structures of several substituted isoindolines that have been frequently used as starting materials for phthalocyanines, phthalocyanine analogs and related chelates. The structures of 1,3-diiminoisoindoline (1), 1,3-bis(hydroxyimino)isoindoline (2), 1,4-diaminophthalazine (3), 1,1,3-trichloroisoindoline (4) and 3-imino-1-oxoisoindoline (5) are reported; compounds 2 and 3 are synthesized from diiminoisoindoline (1) and 4 and 5 are produced from phthalimide. All five compounds are planar macrocycles, and localization of double bonds can be readily determined. We elucidated one of the known structures of 1 at low temperature, and observed two additional new structures of 1. For the crystal forms of 1 and compounds 2, 3, and 5, hydrogen bonding in the solid state was observed. Compounds 1, 2 and 3 form extended hydrogen bonded arrays in the solid state, whereas 5 forms discrete hydrogen bonded dimers.

Full text of DOI:10.1142/S1088424613500107

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2013; 17: 1–10
DOI: 10.1142/S1088424613500107
Published at http://www.worldscinet.com/jpp/
The structures of several modified isoindolines, the building
blocks of phthalocyanines
James T. Engle, Ashley N. Allison, Joshua M. Standard, Ingrid-Suzy Tamgho and
Christopher J. Ziegler*◊
Department of Chemistry, University of Akron, Akron, OH 44325-3601, USA
Dedicated to Professor Evgeny Luk’yanets on the occasion of his 75th birthday
Received 11 December 2012
Accepted 24 January 2013
ABSTRACT: This report presents the single crystal X-ray structures of several substituted isoindolines
that have been frequently used as starting materials for phthalocyanines, phthalocyanine analogs and
related chelates. The structures of 1,3-diiminoisoindoline (1), 1,3-bis(hydroxyimino)isoindoline
(2), 1,4-diaminophthalazine (3), 1,1,3-trichloroisoindoline (4) and 3-imino-1-oxoisoindoline (5) are
reported; compounds 2 and 3 are synthesized from diiminoisoindoline (1) and 4 and 5 are produced
from phthalimide. All five compounds are planar macrocycles, and localization of double bonds can be
readily determined. We elucidated one of the known structures of 1 at low temperature, and observed two
additional new structures of 1. For the crystal forms of 1 and compounds 2, 3, and 5, hydrogen bonding
in the solid state was observed. Compounds 1, 2 and 3 form extended hydrogen bonded arrays in the
solid state, whereas 5 forms discrete hydrogen bonded dimers.
KEYWORDS: 1,3-diiminoisoindoline, 1,3-bis(hydroxyimino)isoindoline, 1,4-diaminophthalazine,
1,1,3-trichloroisoindoline, 3-imino-1-oxoisoindoline, X-ray structures.
In particular, the syntheses of diiminoisoindoline
INTRODUCTION
and similar derivatives has greatly advanced the
The importance of phthalocyanines as both bulk
development of peripherally substituted and asymmetric
colorants as well as specialized materials has driven
phthalocyanines. Notably, great strides in this area
investigations into their synthesis from simple,
have been made by Prof. Eugenii Lukyanets, to whom
readily available starting materials [1–4]. Although
this issue is being dedicated in celebration of his 75th
the phthalocyanines are typically synthesized from
birthday. Lukyanets’ work in this field is extensive and
phthalonitriles, several other convenient reagents can be
has been recently reviewed [11, 12]. Isoindoline derivates
used to produce phthalocyanines and related dyes. Much
have also been used with great frequency for the synthesis
of the pioneering work in this area was carried out by
of compounds structurally related to phthalocyanines.
Linstead in the 1950s [5–9]. During this period, Linstead
For example, this reagent is also useful for the synthesis
produced 1,3-diiminoisoindoline (DII, 1), a key reagent
for the synthesis of phthalocyanines [5, 6, 10]. Compound
1 is a reactive species, and can be readily modified and
derivatized to afford macrocycles, chelates and related
of phthalocyanine analogs, such as subphthalocyanine
[13–15] and the hemiporphyrazines [16–18], and metal
chelates such as the bis(iminopyridyl)isoindoline [18–21]
and phthalazine ligands [22–25].
heterocycles.
Although 1,3-diiminoisoindoline and related
isoindoline derived heterocycles have been studied for
decades, there has been essentially very little elucidation
SPP full member in good standing
via X-ray methods on these compounds. In this report, we
present a study into the structures of several isoindolines
*Correspondence to: Christopher J. Ziegler, email: ziegler@
uakron.edu, tel: +1 330-972-2531, fax: +1 330-972-7370
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J. T. ENGLE ET AL.
Scheme 1.
including diiminoisoindoline 1 and one phthalazine
compound. The structures and syntheses of these
compounds are shown in Scheme 1. The DII derived
compoundsincludethe1,3-bis(hydroxyimino)isoindoline
2 and the 1,4-diaminophthalazine 3. The two remaining
modified isoindolines include 1,1,3-trichloroisoindoline
4 and 3-imino-1-oxoisoindoline 5, which can both
be readily synthesized with phthalimide. There has
been some structural work on these compounds in the
literature. Three crystal forms of compound 1 were
reported at room temperature [26], and compound 5 was
reported as a molecule of co-crystallization with a nickel
complex [27]. These structures show the presence of
localized double and single bonds in the heterocycles, as
well as extensive hydrogen bonding in the solid state for
compounds 1–3 and 5.
trichloroisoindoline 4 [28, 29]. If phthalamide is reacted
with ammonium hydroxide followed by dehydration
with acetic anhydride, o-cyanobenzamide is produced,
which then can be sublimed to produce the 3-imino-1-
oxoisoindoline species 5 [30]. For all five compounds, we
were able to elucidate their structures via single crystal
X-ray methods. The structures of all five compounds are
shown in Figs 1 and 3, and the X-ray data collection and
structure parameters are provided in Table 1.
In 2004, Zhang et al. reported on three crystal forms
of diiminoisoindoline 1 [26]. All three structures were
collected at room temperature, and only the two non-
solvated forms were presented with atom positions,
denoted as forms A and B. In our discussion, we shall
refer to these compounds as 1a and 1b for the two
fully presented structures and form 1c for the methanol
solvate form presented without atom positions. We
were able to obtain a low temperature structure of
form 1a (from methylene chloride solution) where the
molecule crystallizes in the P(2)1/c space group with
two equivalents in the asymmetric unit. The structure of
one of these two equivalents of 1a is shown in Fig. 1.
This compound has three ionizable protons present on
the imine and isoindoline nitrogen atoms. We observed
that the location of these ionizable hydrogen atoms is
different than how this molecule was originally described
by Linstead. In agreement with the observation by Zhang
et al., the difference map shows that the hydrogen
atoms asymmetrically reside on the imine nitrogen atom
positions and not on the central isoindoline nitrogen
position. These hydrogen atoms were located on the
RESULTS AND DISCUSSION
The syntheses of the compounds investigated in this
report have all been previously reported and are shown
in Scheme 1. Diiminoisoindoline 1 is produced via the
reaction of anhydrous ammonia with phthalonitrile in
methanol and thepresence of acatalyticamount of sodium
methoxide, a method first developed by Linstead [5]. We
used compound 1 to make two additional derivatives:
the bis-oxime substituted isoindoline 2 [5, 6, 10] and the
diaminophthalazine 3 [22]. Two additional substituted
isoindolines can be produced from the starting material
phthalimide. The reaction of phthalimide with PCl5 in
o-dichlorobenzene results in the halide substituted variant
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THE STRUCTURES OF SEVERAL MODIFIED ISOINDOLINES, THE BUILDING BLOCKS OF PHTHALOCYANINES
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Fig. 1. The structures of 1a (top left), 1d (top right) and 1e (bottom) with 35% thermal ellipsoids. The asymmetric unit in 1e has 5
1/2 water solvent molecules. Non-ionizable hydrogen atoms and the solvent water molecule hydrogen atoms in 1e have been omitted
difference map, but the assignment can also be made on
the basis of the C–N bond distances of the imine groups.
The C–NH distances for each of the two molecules in
the asymmetric unit are 1.2847(18) and 1.2834(19) Å,
whereas the C–NH2 distances are longer, at 1.3180(18)
and 1.3226(17) Å. Accordingly, the C–N bonds to the
isoindoline nitrogen atom are asymmetric as well, with
lengths of 1.3319(18) and 1.3440(19) Å for the shorter
bonds and 1.4039(17) and 1.396(2) Å for the longer
of the two. Additionally, as seen by Zhang et al., each
equivalent of 1a presents a different stereochemistry
of the imine hydrogen atom, with one syn and one anti
conformation, as shown in Scheme 2.
network of isoindoline dimers. The hydrogen bonding
network array of 1a is shown in Fig. 2. Compound 1a
arranges in hydrogen bonded pairs, forming symmetric
reciprocal hydrogen bonds of ~2.93 Å. These hydrogen
bonds are similar in appearance to those seen in the base
pair hydrogen bonding interaction between purine and
pyrimidine nucleotides. The hydrogen bonded dimers
link together via NH2∙∙∙NH interactions that measure
~2.93 and ~2.99 Å, forming layers composed of nearly
orthogonal pairs of 1.
We also isolated two additional forms of compound
1 which we shall describe as 1d and 1e. Crystal form
1d is also a monoclinic form without solvent molecules,
and the asymmetric unit is shown in Fig. 1. In this form,
we observe a different tautomerization for DII, with one
Compound 1a exhibits a significant degree of hydrogen
bonding in the solid state, forming a three dimensional
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J. T. ENGLE ET AL.
ionizable proton on each of the nitrogen atom positions.
This assignment, which assumes an imine bond to the
external nitrogen atom positions, is supported by the
observed bond lengths. In 1d, the C–N bonds with
the central nitrogen atom are longer than in 1a, measuring
1.387(3) and 1.391(3) Å, and the C–N bonds to the
external nitrogen atom positions are clearly imine in
character, measuring 1.214(3) and 1.218(3) Å. The imine
hydrogen atom positions, although not readily observed
on the difference map, can be inferred to be in the syn
configuration, oriented toward the phenyl ring of the DII.
The imine hydrogen atoms must be in the syn orientation
since the DII units in 1d form hydrogen bonded dimers,
as shown in Fig. 3. The N–H∙∙∙N
Scheme 2.
interactions measure ~2.88 Å.
In the solid state, 1d exhibits
stacks of these hydrogen bonded
dimers, spaced at ~3.37 Å, in an
alternating herringbone fashion.
We isolated a fifth crystal
form of DII, 1e, upon recry-
stallization of
1 from wet
ethanol.Thiscrystalform, which
adopts the C2/m space group,
has three equivalents of DII in
the asymmetric unit, as well as
11 equivalents of water solvent
molecules per unit cell. Four of
the five solvent water molecules
found in the asymmetric unit
are fully occupied, while the
remaining water molecule is
disordered over two positions
with 50% occupancy. In 1e, two
of the equivalents of DII adopt
an asymmetric tautomeric state,
with two ionizable protons on
one external nitrogen atom
and one syn hydrogen atom on
the opposite external nitrogen
atom. The C–N bond lengths in
these two equivalents support
the proton assignment. The NH
imine bonds exhibit lengths of
1.255(3) and 1.283(4) Å, the C–
NH2 bonds are longer (1.302(3)
and 1.304(3) Å) and the internal
C–N bonds exhibit single and
double bond character (1.334(3)
and 1.379(3) Å; 1.330(4) and
1.382(4) Å). The remaining
equivalent of DII was modeled
with a disordered hydrogen atom
with 50% occupancy on the
central nitrogen atom position
and 50% on one of the two
external nitrogen atom positions.
The nitrogen atom position is
Fig. 2. Hydrogen bonding formed between DII units for 1a, (left) 1d and 1e (right). 1d and
1e have identical hydrogen bonding between equivalents of DII in the solid
Fig. 3. The structures of 2–5 with 35% thermal ellipsoids. Non-ionizable hydrogen atoms
and the solvent water molecule in 3 have been omitted for clarity
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THE STRUCTURES OF SEVERAL MODIFIED ISOINDOLINES, THE BUILDING BLOCKS OF PHTHALOCYANINES
7
not disordered. This disordered tautomerization is based
on observed differences in bond lengths. The C–N bond
(1.274(3) Å) for this disordered tautomer is intermediate
between the amine and imine bonds seen in the other
forms of 1. Additionally, the internal C–N bonds are
longer as well (1.361(3) and 1.374(3)) implying some
degree of single bond character, but not as long as that
seen in similar bonds in 1d.
Hydrogen bonding is extensive in crystal form 1e.
The equivalents of DII form hydrogen bonded dimers
essentially identical to that seen in 1d (~2.89, ~2.89 and
~3.02 Å). Additionally, all of the water molecules in 1e
form eight hydrogen bonds with the external nitrogen
atom positions, ranging in N∙∙∙O lengths from ~2.73 to
~3.07 Å. There is also hydrogen bonding between water
molecules in the solid state, ranging from ~2.68 to ~2.76
Å. The presence of this extended hydrogen bond network
of water molecules affects how the hydrogen bonded
dimers pack in the solid state in 1e. The dimers pack in two
ways in the unit cell: pairs of dimers form stacks spaced
by ~3.70 Å, and these stacks are separated by monolayers
of dimers that are orthogonal to the plane of the stacked
layers, in contrast to the herringbone pattern in 1d.
The reaction of hydroxylamine hydrochloride with
compound 1 results in the bis-oxime derivative of DII
2. Compound 2 crystallizes in the orthorhombic space
group Pmna, and the asymmetric unit is comprised of
one half of the molecule. The structure of this compound
is shown in Fig. 3. The molecule is also planar, with the
oxime units occupying the same plane as the isoindoline
and the entire molecule exhibiting a mean deviation from
planarity of ~0.01Å. Accordingly, unlike compound 1,
inspection of the bond distances shows the more expected
symmetric structure. The oxime unit exhibits a clear
C–N double bond at 1.2870(18)Å, whereas the C–N
bond to the isoindoline central nitrogen atom is longer
at 1.3840(17) Å. The oxime N–O distance measures
1.4132(16), which is clearly a single bond.
There are three ionizable protons on compound 2, with
one on each oxime oxygen and one on the central nitrogen
atomoftheisoindoline.Thiscompoundexhibitshydrogen
bonding between the oxime OH units and oxime nitrogen
atoms on neighboring equivalents of 2, however there is
no observed hydrogen bonding to the central NH group
of the isoindoline. The hydrogen bonding interactions in
2 are shown in Fig. 4. The OH∙∙∙N heteroatom distances
Fig. 4. Hydrogen bonding networks formed by compounds 2 and 3
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J. T. ENGLE ET AL.
measure ~2.74 Å, and result in herringbone-like layers of
2 in the solid state. The herringbone layers are comprised
of stacks of compound 2, with isoindoline–isoindoline
spacings of 3.30 Å.
hydrogen bonding interaction via the internal N–H
group of the isoindoline and via an anti-configuration
of the imine N–H unit, which acts as a hydrogen bond
acceptor. Additionally, the acyl oxygen of the previously
elucidated compound interacts with an N–H unit from
the dithiobiurea ligand to form a hydrogen bond.
When diiminoisoindoline 1 is reacted with hydrazine,
a nitrogen atom inserts into the isoindoline heterocycle to
afford a diaminophthalazine, compound 3. The structure
of 3 is shown in Fig. 3. The molecule crystallizes in the
C2/c space group, and as in compound 2 the asymmetric
unit is comprised of one half of the heterocycle. As in
the above compounds, this molecule is also planar, with
an average deviation of ~0.01Å. The aromaticity in
phthalazine extends over the heterocycle portion of the
compound, however the presence of heteroatoms does
induce some bond alternation effects. The phthalazine
portion of the macrocycle clearly shows localized double
bond character between the nitrogen atoms and carbon
atoms, with a length of 1.306(2) Å. The phthalazine N–N
distance is longer, with a distance of 1.384(2) Å.; The
C–N bonds to the exocyclic nitrogen atoms are clearly
single, with lengths of 1.3906(19) Å.
Compound 3 engages in hydrogen bonding with itself,
via NH∙∙∙N interactions as well as to an equivalent of
solvent water found in the asymmetric unit, as shown in
Fig. 4. The diaminophthalazine NH∙∙∙N hydrogen bonds
(~3.01 Å) form nearly co-planar linear arrays, forming
a total of four such bonds per diaminophthalazine. The
hydrogen bonds to the solvent water, which bridge
between the linear arrays of compound 3, are slightly
shorter, measuring ~2.96 and ~2.83 Å. The linear arrays
of 3 form p stacks with distances of ~3.52 Å.
The compound presented herein crystallizes in
the P2(1)/n space group, and the asymmetric unit is
comprised of a single equivalent of the molecule, also
shown in Fig. 3. The C–O length is clearly double bond
in character (1.212(2)Å) and the exocyclic C–N bond is
clearly an imine, with a length of 1.218(2)Å. The C–N
bonds to the indoline nitrogen atom are longer, measuring
1.401(2) and 1.383(2)Å in length, with the shorter bond
observed with the imine carbon atom. The observation of
these bond lengths is counterintuitive, since one might
expect there to be a greater degree of resonance with the
acyl carbon atom than the imine carbon atom. There are
two ionizable hydrogen atoms present in compound 5,
with one present on each of the nitrogen atom positions.
The imine N–H group is oriented syn to the aromatic ring
of the isoindoline.
In the solid state, compound 5 forms discrete
hydrogen bonded dimers via the isoindoline N–H group
and the imine nitrogen atom position, as shown in Fig. 5.
Thus, the hydrogen bonding is symmetric, with N–H∙∙∙N
lengths of ~2.88Å. There are no observed extended
Unlike compounds 2 and 3, the trichloroisoindoline
4, shown in Fig. 3, is produced via the reaction of
phthalimide with PCl5. This compound crystallizes in the
orthorhombic space group Pnma and the heterocycle lies
on a reflection plane (i.e. the asymmetric unit is half of
the macrocycle). As in diiminoisoindoline 1, compound
4 has asymmetric bonding around the central nitrogen
atom, with a C–N double bond (1.278(2) Å) and a C–N
single bond (1.472(2) Å). The C–Cl bonds also differ;
the C–Cl bond on the sp2 hybridized carbon measures
1.706(2) Å whereas the sp3 C–Cl bonds are 1.7848(11) Å.
Since there are no heteroatom-bound hydrogen atoms in
the structure, there is no hydrogen bonding in the solid
state structure of 4. The molecules pack in a head-to-tail
fashion, and stack in anti-parallel sheets with a distance
of ~3.45 Å.
The oxygen substituted analog of diiminoisoindoline,
3-imino-1-oxoisoindoline 5 can be produced via a three
step reaction from phthalimide, and the final thermal
cyclization and sublimation steps produces single crystals
that can be readily structurally elucidated. Previously, this
compound was observed as a co-crystallizing molecule
with bis(dithiobiureto)nickel(II) [27]. In this structure,
the 3-imino-1-oxoisoindoline forms a strongly hydrogen
bonded interaction with the back end of the dithiobiurea
ligand. The 3-imino-1-oxoisoindoline engages in its
Fig. 5. Hydrogen bonded dimer structure formed in compound 5
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THE STRUCTURES OF SEVERAL MODIFIED ISOINDOLINES, THE BUILDING BLOCKS OF PHTHALOCYANINES
9
hydrogen bonding linear arrays in the solid state, as
seen in compounds 1–3. This hydrogen bonding is also
very similar to that seen in the co-crystallized structure
with bis(dithiobiureto)nickel(II). The hydrogen bonded
dimers form slipped stacked arrays, with distances of
~3.37 Å between the planes of the isoindolines, and these
stacked arrays form a herringbone pattern in the solid
state.
mixture yielded yellow/orange crystals. Yield: 492 mg
(92%).
1,1,3-trichloroisoindoline (4). The synthesis of this
compound followed a modified literature procedure
[28, 29]. PCl5 (1.75g, 8.42mmol) was dissolved in
o-dichlorobenzene (1.63mL, 11.1mmol), then phthalimide
(600mg, 4.08mmol) was added. The reaction mixture was
heated to 95–100 °C under an argon atmosphere. After
2 h, a clear solution was formed and was heated for 3
more hours with no visible change. POCl3 was distilled
under aspirator pressure at 40 °C. After all of the POCl3
was removed, the temperature was raised to 80 °C and
o-dichlorobenzene distilled. While the temperature
reached 105 °C, white crystals formed in the flask. The
residue was recrystallized in cyclohexane to yield 368 mg
(1.67 mmol, 40%) of a white solid. These crystals were
suitable for structure elucidation via single crystal X-ray
diffraction.
3-imino-1-oxoisoindoline (5). This compound
was prepared via a three step process starting with
phthalimide using the procedure presented by Murthy
et al. [30]. Phthalimide (10.0 g, 0.07 mol) was suspended
in 60 mL of ammonium hydroxide for 24h, and the
resultant phthalamide was isolated by filtration and
washed with water, affording 10.1g (85% yield).
After drying, 10 g of the phthalamide was dissolved in
70 mL of acetic anhydride and refluxed for 2h. Upon
cooling of the reaction solution, a white solid formed
(o-cyanobenzamide) that was collected and washed with
cold ethanol, producing 3.0g of product (40%). The
o-cyanobenzamide was simultaneously cyclized and
sublimed under nitrogen gas at atmospheric pressure to
afford crystals of 5 (1.0g, 33%) that were suitable for
structure elucidation via single crystal X-ray diffraction.
EXPERIMENTAL
General methods
Unless otherwise stated, all reagents and solvents
were purchased from Sigma, Aldrich, Acros Organics,
or Strem and used without further purification. Solution
NMR spectroscopy was performed with Varian VXR 300
MHz and Varian 500 MHz NMR instruments. Elemental
analyses were carried out at the School of Chemical
Sciences Microanalytical Laboratory at the University
of Illinois at Urbana-Champaign. Mass spectrometric
analyses were carried out at the Mass Spectrometry
and Proteomics Facility at The Ohio State University in
Columbus, OH or at the University of Akron in Akron,
OH.
Synthesis
1,3-diiminoisoindoline (1). This compound was
synthesized according to a modified literature procedure
[2a]. Crystals suitable for single crystal X-ray diffraction
were grown from dichloromethane solution, affording
crystal form 1a. Crystals were also obtained from butanol
solution (form 1d) and from wet ethanol (form 1e).
1,3-bis(hydroxyimino)isoindoline (2). We used
a modification of Linstead’s procedure to synthesize
compound 2 [2a, 2b, 3]. 1,3-diiminoisoindoline (100 mg,
0.68 mmol) was dissolved in 10 mL of methanol with
gentle heating. Three equivalents of hydroxylamine
hydrochloride (144 mg) was also dissolved in 10 mL of
methanol and the two solutions were mixed. The mixture
was then allowed to sit at room temperature and slowly
evaporate until crystals of the product formed, which
were then collected by filtration. These crystals were
suitable for X-ray structure elucidation. Yield: 117 mg
(96%).
1,4-diaminophthalazine (3). This reaction was based
on work first published by Fujii [22] and later successfully
used by Lever to synthesize substituted phthalazines
[24]. 3.5 mmol of 1,3-diiminoisoindoline (500 mg)
was heated in methanol and allowed to dissolve. The
reaction mixture was then removed from heat and while
the reaction mixture was still hot, ~1.7 mL of hydrazine
hydrate was added drop wise to the solution. The reaction
mixture was allowed to sit for a few hours, during which
time crystals of the product formed that were suitable for
single crystal X-ray diffraction. Vacuum filtration of the
X-ray crystallography
Single crystal X-ray diffraction data were collected
at 100 K (Bruker KRYO-FLEX) on a Bruker SMART
APEX CCD-based X-ray diffractometer system equipped
with a Mo-target X-ray tube (l = 0.71073 Å) operated at
2000 watts power. The detector was placed at a distance
of 5.009 cm from the crystal. Integration and refinement
of crystal data was done using Bruker SAINT software
package and Bruker SHELXTL (version 6.1) software
package, respectively. Absorption corrections were
carried out using the SADABS program [31]. Crystals
were placed in paratone oil upon removal from the
mother liquor and mounted on a plastic loop in the oil.
Data collection and structure parameters can be found in
Table 1.
CONCLUSION
In conclusion, we have structurally elucidated five
isoindoline derivatives that have been historically
investigated as starting materials for phthalocyanines,
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J. T. ENGLE ET AL.
phthalocyanine analogs and metal chelating ligands.
As expected, all five compounds are planar, with the
exception of the chlorine atoms on compound 4. The
location of the double bonds in these compounds can
be unambiguously determined from the elucidated
structures. In compounds 1 and 3, we observed exocyclic
amine groups, and in 1, 2 and 5 there are clear C–N
double bonds to exocyclic nitrogen atoms. With the
exception of compound 4, all of the compounds in this
report engage in hydrogen bonding in the solid state, with
most of the compounds (1, 2 and 3) forming hydrogen
bond polymeric structures, and with 5 forming discrete
dimers. We are continuing our work on the structure
elucidation of isoindoline derived compounds, and hope
that the current work will assist others in understanding
the structural aspects of isoindoline-based macrocycles,
as well as in related areas, such as the construction of
hydrogen bond network solids.
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The authors would like to thank the University of
Akron for support of this research.
Supporting information
Crystallographic data have been deposited at the
Cambridge Crystallographic Data Centre (CCDC) under
numbers CCDC-914960-914966. Copies can be obtained
on request, free of charge, via www.ccdc.cam.ac.uk/
data_request/cif 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).
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J. Porphyrins Phthalocyanines 2013; 17: 10–10