Transition metal molecular glasses by design: Mexylaminotriazine-functionalized salicylaldehyde imine ligands

Article abstract of DOI:10.1039/c9nj01159e

Mexylaminotriazines are a novel class of small molecules capable of forming stable glassy phases. When covalently linked to a variety of small molecules, mexylaminotriazines possess the ability to introduce resistance to crystallization and yield stable g

Full text of DOI:10.1039/c9nj01159e

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ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
rsc.li/njc

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Transition metal molecular glasses by design:
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Mexylaminotriazine-functionalized salicylaldehyde imine ligands
Mahboubeh Jokar,a Michael Cherry,a Jennifer Scott*a and Olivier Lebel*a
Received 00th January 20xx,
Accepted 00th January 20xx
Mexylaminotriazines are a novel class of small molecules capable of forming stable glassy phases. When covalently linked
to a variety of small molecules, mexylaminotriazines possess the ability to introduce resistance to crystallization and yield
stable glassy phases for various other moieties that are traditionally unable to readily adopt glassy phases. To date, this
has been applied particularly to opto-electronic devices. However, there is limited information regarding the synthesis of
glass-forming metal complexes. Herein, a library of salicylaldehyde imine derivatives incorporating mexylaminotriazine
substituents were synthesized, from which respective complexes with various first-row transition metals were prepared.
The resulting compounds were characterized and evaluated for their glass-forming properties. It was found that all
synthesized ligands and complexes demonstrated the ability to adopt glassy phases; however, the metal centre was
identified as having a profound impact on the glass transition temperature (Tg). Additionally, it was found that the
incorporation of mexylaminotriazine moieties to ligand frameworks may present a reliable and predictable strategy for the
DOI:
10.1039/x0xx00
000x
introduction
of
glass-forming
properties
into
a
variety
of
metal
complexes.
crystallizing more rapidly than polymers. As a result, is it
difficult to access the glassy state for small-molecule materials
outside of special processing techniques, such as quenching
with liquid nitrogen.11-12 Even in amorphous samples,
crystallization readily occurs upon cooling over their glass
transition temperature (Tg), or on standing over longer periods
of time. Small molecules destined for thin-film applications
must therefore possess molecular structures specifically
engineered to resist crystallization. Such compounds are called
molecular glasses, or amorphous molecular materials.13-16
Through various studies, structural parameters have been
established that promote the formation of glassy phases as
opposed to crystals, such as irregular shapes, non-planarity,
and conformational equilibria.13-16 Following these guidelines,
compounds that can readily form glassy phases and remain
amorphous for extended periods of time may be designed and
synthesized.
Introduction
Coordination compounds can access a range of properties
normally inaccessible for organic compounds due to the
presence of metal ions.1 The structural and electronic interplay
between ligands and metals affects a variety of properties,
including magnetism, conductivity, and luminescence.1 The
ability to achieve control over these properties in the solid
state is crucial for various applications, including opto-
electronics, sensors, and solid-state catalysis, and therefore,
these compounds require some form of support for effective
use.2-6 Due to the increasing complexity of many devices and
processes, the incorporation or support of functionalities onto
thin films is a desirable strategy for the development of many
materials destined for solid-state applications, such as optical
storage devices, magnetic storage materials, and other
electronic components.7-9
Despite advances in the synthesis of glass-forming organic
compounds, there are few reported instances of glass-forming
coordination compounds with low molecular weights and
discrete structures. In some of these cases, the complexes
themselves are capable of glass formation, but not necessarily
the ligands, and not all of these reported complexes can form
glasses upon slow cooling.17,18 In order to obtain coordination
compounds that can readily form glasses through rational
design, it is imperative to develop ligands that also share an
Currently, the most common method of incorporating
specific functionalities into thin films intended for solid-state
applications is by generating functionalized polymers.8,10
However, the alternative use of glass-forming small molecules
offers a number of advantages. Due to their reduced and
definite size, small molecules are easier to purify and
characterize, and their monodisperse nature results in
homogeneous behaviour between samples.11-12 Furthermore,
small molecules are less sensitive to effects arising from chain
entanglements and other rheological phenomena associated
with polymer backbones. However, due to their unhindered
mobility, small molecules possess the disadvantage of
appreciable glass-forming ability. By using
mexylaminotriazine units as common precursors, our group
has developed reliable synthetic strategy for the
spontaneous formation of glassy phases for organic materials
a class of
a
a. Royal Military College of Canada, Department of Chemistry and Chemical
Engineering, Kingston, ON, Canada, K7K 7B4
† Footnotes relating to the title and/or authors should appear here.
Electronic Supplementary Information (ESI) available: TGA scans of complexes 8M-
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10M, DSC traces of compounds 1-10, XRD pattern of complex 8Co
DOI: 10.1039/x0xx00000x
. See

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with very high resistance to crystallization, even at
temperatures above Tg.19-21 These mexylaminotriazine
derivatives can frustrate crystallization by adopting various
conformers of similar energy with high interconversion
barriers, and by forming hydrogen bonds that can further limit
mobility in the solid state.19-21 By synthesizing such molecular
glasses, various functionalities, including chromophores or
semiconductors, can be incorporated to give adducts that
retain the glass-forming properties of the parent
compounds.22-23 Using this strategy, the preparation of glass-
forming ligands, and their corresponding coordination
complexes, can be envisaged.
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Herein, we report the synthesis of
a family of
salicylaldehyde imine derivatives, and representative
complexes with various first-row transition metals,
incorporating mexylaminotriazine moieties. Salen ligands
constitute an ideal family of ligands for an initial study; they
are well-described in the literature, they form stable
complexes with most metals, and in the majority of
compounds, either no additional ligands are required, or their
identity is easy to control.24-30 For these reasons, there is a
higher probability that the complexes share the glass-forming
properties of the parent ligand, and that the resulting
complexes are easier to purify and characterize than
complexes that are either heteroleptic or that contain weakly
bonded ligands or counterions. As expected, all of the ligands
synthesized herein proved capable of forming glasses with no
crystallization, and all of the complexes shared the glass-
forming properties of the parent ligand. The current study
constitutes the first reported example of functionalization by
glass-forming moieties as a powerful strategy to synthesize
both glass-forming ligands and coordination compounds by
design. The role of the metal centre is identified as a new
factor influencing the glass-forming properties of the prepared
complexes.
Scheme 1. Synthesis of mexylaminotriazine functionalized salicylaldehyde 1.
Salicylaldehyde
1 could be directly condensed with
ethylenediamine or (1R,2R)-1,2-diaminocyclohexane to yield
symmetrical salen ligands 6 and 7 in 93-95% yield (Scheme 2).
However, attempts to condense compound 1 with 1,2-
phenylenediamine failed to give the desired product. Instead,
an unidentified side product was isolated. Currently under
closer investigation, the product may be the result of a
parasitic cyclization followed by an intramolecular hydrogen
transfer to yield
a
benzimidazole derivative. Similar
condensations have been previously reported in the literature,
especially upon condensation of 1,2-phenylenediamine with
salicylaldehydes bearing highly electron-donating groups.33-34
Results and discussion
Ligand synthesis
Salicylaldehyde-functionalized glass
1
was synthesized
according to Scheme 1. The ethylene glycol acetal of 4-
aminosalicylaldehyde 331 was first prepared by the reduction
of nitro derivative 2 with PMHS and Pd(OAc)2.32 As derivative 3
can readily self-condense to yield a polyimine, attempts to
react it directly with 2-methylamino-4-mexylamino-6-chloro-
1,3,5-triazine using the procedures previously established in
our group20 for the synthesis of molecular glasses failed.
Instead, the intermediate was immediately reacted with 2-
mexyl-4,6-dichloro-1,3,5-triazine 4 at ambient temperature in
a one-pot procedure, in which the acetal was hydrolyzed
during purification, to give 6-chlorotriazine intermediate 5 in
91 % yield. Substitution of the last chloride with aqueous
methylamine yielded glass 1 in 79 % yield (Scheme 1). In both
steps, the products could be easily purified by acidic and basic
extractions, and did not require chromatography.
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to obtain complex 8Mn in 61% yield.38 The dark brown Fe(III)
complex 8Fe was synthesized in 76 % yield from the respective
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DOI: 10.1039/C9NJ01159E
chloride salt in THF/EtOH in the presence of triethylamine as a
base (Scheme 3).39 Finally, Co(II),40 Ni(II),41 and Cu(II)41
complexes (8Co, 8Ni, 8Cu) were synthesized in 66-84 % yield by
refluxing with the corresponding acetates in THF/EtOH. For the
Co(II) complex 8Co, the reaction was run under an inert
atmosphere to prevent oxidation. In all cases, the complexes
were purified by precipitation with water followed by
filtration, as excess amounts of the metal salts were used and
could be conveniently removed.
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Scheme 2. Synthesis of salen ligands 6-10.
Scheme 3. Preparation of coordination complexes from ligands 8-10.
Although ligands 6-7 are simple and straightforward to
synthesize and purify, the presence of two mexylaminotriazine
units leads to low solubility except in polar aprotic solvents
such as THF, DMF, and DMSO, and causes an important
increase in molecular weight, thereby needlessly diluting the
ligand core in the material. However, it has already been
shown in the literature that only one mexylaminotriazine unit
is required for glass formation, even in polyfunctional
compounds.35 Therefore, asymmetrically substituted ligands 8-
10, which contain one mexylaminotriazine-functionalized
salicylaldehyde and one unfunctionalized salicylaldehyde unit,
were synthesized (Scheme 2). While ethylene-bridged ligand 8
could be synthesized directly in 93 % yield from the three
As the complexes derived from ligand 8 proved significantly
less soluble than their parent ligand, no complexes were
synthesized using symmetrically disubstituted ligands 6-7,
which are already sparsely soluble in most solvents. However,
for the purpose of comparing ligands, Zn(II) complexes of
ligands 8-10 were prepared, yielding the respective products,
8Zn, 9Zn and 10Zn (Scheme 3). For both 8Zn and 9Zn, the
commonly used procedure42 with Zn(OAc)2 resulted in some
ligand disproportionation during the reaction. For this reason,
triethylamine (2.3 equiv) was added to
a solution of
ZnCl2∙2H2O (1.1 equiv.) and ligand 8 or 9 in EtOH and the
mixture was refluxed for 30 minutes, yielding the yellow
complexes in 77 and 76% yields, respectively. For the synthesis
of product 10Zn, Zn(OAc)2∙2H2O (excess) in EtOH was added to
a stirring solution of ligand 10 in THF and refluxed for 2 h.
Despite the larger diamino substituents, complexes 9Zn-10Zn
showed the same solubility as the ethylene-bridged derivative
8Zn.
components in
a
one-pot procedure, the respective
monoimines with salicylaldehyde were first prepared for
ligands 9 and 1036-37 and then condensed with glass 1 to yield
the products in two steps and overall 82-90 % yields. While
this approach is more time-consuming for ligands 9-10,
compounds 8-10 are soluble in a wide range of solvents from
toluene to methanol.
Thermal properties
Coordination with First-Row Transition Metals
Precursor 1 and ligands 6-10 readily form glasses upon
drying from solution, or by cooling from the viscous state.
Differential Scanning Calorimetry (DSC) was used to measure
their respective glass transition temperatures (Tg), listed in
Table 1. In all cases, the respective compounds showed a glass
transition and no crystallization was observed upon heating
(Figures S1-S2), demonstrating the ability of salen derivatives
Ligand 8 was reacted with various first-row transition metals
including Mn(III), Fe(III), Co(II), Ni(II), and Cu(II) according to
published procedures for Salens to yield the corresponding
complexes (Scheme 3). The brown Mn(III) complex 8Mn was
synthesized from manganese(II) acetate in refluxing THF/EtOH
under air, followed by a ligand exchange with lithium chloride
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6-10 to form stable, long-lived glasses. Salicylaldehyde 1 shows
a Tg of 81 ºC, which is similar to analogous compounds.20 While
monofunctionalized ligands 8-10 show similar Tg values
ranging from 69 to 99 ºC, bis(mexylaminotriazine) ligands 6
and 7 show higher Tg values of 125 and 131 ºC, which follows
trends previously observed for compounds with more than
one mexylaminotriazine group.20 The fact that ligands 8 and 10
show Tg values lower than that of precursor 1 is likely due to
the higher flexibility of the salen core, especially in the
absence of a transition metal. The Tg of 10 may be lower than
8 and 9 due to the lower basicity of the arylimino N atoms,
thereby engaging in fewer, or weaker, hydrogen bonding with
the amino NH groups on adjacent triazines, or by forming
weak π-π interactions with the mexyl groups, thereby
generating additional disorder in the system.
The thermal behaviour of the complexes was studied by
Thermogravimetric Analysis (TGA) and DSC and the
decomposition temperatures and Tg values are reported in
Table 1. Typically, a first mass loss peak ranging from 2 to 8 %
was observed around 140 °C, and is the result of loss of either
coordinated or residual water trapped in the samples. As
molecular packing is poor in organic glassy solids, important
void spaces are present and are typically occupied by guest
molecules.11-12 The same would be expected of coordination
complexes of glassy ligands. Most compounds are stable over
250 °C, except for the Co(II) complex 8Co, which decomposes at
approximately 170 °C as reported by TGA, though it can
undergo oxidation to Co(III) at lower temperatures in the
presence of oxygen. Like their parent ligands, all complexes
were capable of forming glassy phases, with Tg values ranging
from 133 to 196 °C. Only the Co(II) complex 8Co did not show a
glass transition, potentially due to thermal degradation or
oxidation with residual oxygen. In this case, the amorphous
nature of the compound was confirmed by XRD (Figure S3). No
crystallization was observed for any complex upon heating to
250 °C. It is to be noted that all Tg values reported herein were
recorded after an initial heating-cooling cycle in which the
materials were heated above Tg to erase the thermal history
and remove any trace of residual water in the case of the
complexes. The Tg values remained consistent between
different scans.
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DOI: 10.1039/C9NJ01159E
8Fe
8Co
8Ni
Fe(III)Cl
Co(II)
Ni(II)
270
170
240
250
250
290
280
196
-
133
159
146
165
167
8Cu
8Zn
9Zn
10Zn
Cu(II)
Zn(II)
Zn(II)
Zn(II)
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The Tg values for the transition metal complexes were
significantly higher than those of their parent ligands, which is
to be expected given the loss of degrees of liberty resulting
from the presence of the metal atom, which forces the salen
moiety into a particular conformation.
Interestingly, significant variations in Tg were observed
depending on the nature of the metal center. Of the
complexes synthesized herein, the trivalent species 8Mn and 8Fe
have a significantly higher Tg than their divalent analogues, at
179°C and 196°C, respectively. For the analogous divalent
complexes, a range of 26 °C was observed: 8Ni (133 °C), 8Cu
(159 °C), and 8Zn (146 °C). Salen complexes are known to adopt
a variety of structural motifs, the most common being
anhydrous and mono- or di-hydrated monomers, or dimers via
bridging phenoxides, coordinated water, or oxides
(representative possible intermolecular interactions are shown
in Scheme 4).24-30,42-60 The differences in Tg may be explained in
part by the geometrical associations adopted by the particular
metal center as well as additional intermolecular interactions
occurring in each system. Not only can the complexes dimerize
through bridging ligands, but nitrogen atoms on the triazine
moieties from neighbouring complexes may also bind the
metal centers, most likely disrupting phenoxide dimerization,
but increasing connectivity amongst units. Triazines, especially
those contained within a melamine scaffold, are known to be
more basic than pyridine, and complexes displaying triazine
coordination are well established in the literature (Scheme
4).61-64 In addition to associations through metal binding, the
mexylaminotriazine unit is well known to engage in extensive
intermolecular hydrogen bonding.65 Indeed, the percentage of
possible hydrogen bonding occurring in the glassy state has
been calculated to be 70%.65 The amino hydrogen atoms may
interact with the nitrogen atoms of the triazine rings,
additional amino groups, the phenoxides of the ligand, as well
as the aryl rings (Scheme 4). As seen with hydrogen bonding,
strong intermolecular interactions are known to lead to
substantial increases in Tg,65 therefore it is expected that dimer
formation, or formation of higher associations, through any of
these interactions will lead to higher Tg values proportional to
the amount of dimer in the solid state. Due to the degree and
variety of possible interactions, the overall picture, and hence
resulting Tg, may vary widely from metal to metal.
Table 1. Decomposition temperatures and glass transition temperatures (Tg) for ligands
and complexes.
Compound
Metal
Tdec (°C)
Tg (°C)
81
1
6
-
-
-
-
125
131
78
7
-
-
8
-
-
9
-
-
-
99
10
8Mn
-
69
Mn(III)Cl
290
179
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water (which is likely removed in DSC during the iVnieitwiaAlrtihcleeaOtnilninge
cycle), Zn has been shown to thermodynamically favour
DOI: 10.1039/C9NJ01159E
Scheme 4. Representative possible intermolecular interactions of complexes 8M-10M in
dimerization via bridging phenoxides,53 and indeed forms
anhydrous dimers upon sublimation and deposition into thin
films.53 In addition, Zn Salen complexes have also been shown
to coordinate pyridine with an association constant several
orders of magnitude higher than that for dimer formation,67
which suggests that triazine N atoms can also coordinate the
metal centres of neighboring molecules, thereby leading to the
formation of both square pyramidal metal centers and larger
aggregates. Indeed, a similar pattern may be adopted for
complex 8Cu. In this case, the metal center is most likely square
pyramidal,54 as evidenced by the observed green colour in the
solid state.68 The higher value of Tg for 8Cu than 8Zn follows the
Irving-Williams series and is a direct result of the softer nature
of d10 Zn2+ and increased acidity of Cu2+, which results in an
augmented tendency to bind adjacent triazine units and create
higher order associations.
Co(II) salen complexes are known to form both monomeric
square planar structures55-56 and dimeric square pyramidal
structures upon crystallization.57-60 However, Co(II) salen
complexes are also known to readily bind O2,30,69 behaviour
that is encouraged by the presence of H-bonding moieties in
appropriate arrangements on the ligand backbone,69 and to
oxidize easily.70 Even if the DSC is run under inert atmosphere,
the presence of oxygen in the sample would make it likely for
the compound to oxidize and decompose before reaching glass
transition.
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the amorphous state.
Similar versions of non-glassy salen complexes of Mn(III)
and Fe(III) commonly form dimers in the solid state, generally
via bridging phenoxides or water.43,49 However, these were
observed in the crystalline state, where only the most
favourable interactions prevail. In the amorphous state, it is
likely that the Cl atoms also serve to bridge neighboring metal
centers in a lower proportion. The Cl ligands can also interact
with the NH groups and the electron-deficient triazine rings,
which could also lead to higher Tg values due to stronger
intermolecular interactions. In addition, the increased Lewis
acidity of the trivalent metal centers compared to their
divalent counterparts may encourage increased binding by
adjacent triazine units, disrupting phenoxide or chloride
bridging while generating more molecular associations. The
existence of several molecular species in equilibrium may
improve glass formation and resistance to crystallization by
further frustrating the efficient and ordered packing of
molecules, thereby resulting in increased values of Tg.
For the Zn(II) complexes, the Tg values for the larger
phenylene and cyclohexyl-bridged ligands 9Zn-10Zn were similar
to each other and higher than the ethylene-bridged complex
8Zn. This trend is different from that seen by the bare ligands,
because the conformation of the salen moiety in all three
complexes, which is rigidified by the presence of the metal
center, is expected to be similar, thereby increasing the Tg
dependence on ligand size.
The lower values for Tg for the divalent complexes suggest
Conclusions
a
different degree or variety of molecular association
Mexylaminotriazine molecular glasses functionalized with
salen ligands were successfully synthesized. A series of
successive substitution reactions were utilized to prepare a
glass-forming salicylaldehyde, 2-mexylamino-4-methylamino-
6-[(4-hydroxy-3-formylphenyl)amino-1,3,5-triazine, in good
yield, which is a useful building block as it could be used as the
common precursor to synthesize several glass-forming
compared to the trivalent complexes, and the trend appears to
follow the Irving-Williams series (Ni2+ < Cu2+ > Zn2+).66 In the
case of 8Ni, the diamagnetic nature of this complex suggests a
square planar Ni center, negating the presence of dimers and
coordination by triazines. This is not surprizing given the
tendency for Ni to adopt the more energetically favourable
square planar geometry and is common among regular Ni
salen complexes.50 This apparent lack of direct coordination-
induced intermolecular association may explain the lower
value obtained for the Tg of 8Ni.
Geometry determinations for the d9 and d10 Cu(II) and
Zn(II) complexes are not as straightforward. Salen-Zn has the
tendency to become hydrated, forming a square pyramidal
structure.51-52 The larger initial mass loss in the TGA of Zn
compared to Ni and Cu (almost twice as much) may indicate a
degree of water coordination. However, upon removal of
salicylaldehyde-based
functionalized salicylaldehyde
ligands.
Mexylaminotriazine-
was reacted through
1
a
condensation mechanism with salicylaldehyde and
ethylenediamine, (1R,2R)-1,2-diaminocyclohexane, or 1,2-
phenylenediamine to generate the respective glass-forming
salen ligands. The yields obtained were good and the resulting
ligands demonstrated the ability to readily form long-lived
glasses. The ligands were subsequently reacted with first-row
transition metal salts under reflux conditions in order to give
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the corresponding transition metal complexes in good yields. added dropwise via syringe (Caution! Rapid addition of PMHS
While the number of mexylaminotriazine units and the can result in uncontrollable gas evolution!). The reaction was
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diamine backbone were found to impact Tg, the metal ions stirred for 45 min or until complete as judged by TLC. At that
proved to have the most pronounced impact on Tg, with a time, the reaction flask was opened to the air, then a solution
range of values from 133 to 196 °C for the ethylene series. The of 4,6-dichloro-2-mexylamino-1,3,5-triazine (4) (0.268 g, 1.00
differences in Tg are likely due to the formation of bridged mmol) in acetone (5 mL) was added dropwise to the mixture.
dimers or higher order associations in the glassy state, which K2CO3 (0.138 g, 1.00 mmol) was then added, and the mixture
are expected to increase Tg in a similar fashion to other types was stirred for 4 h at ambient temperature. The catalyst was
of noncovalent interactions, most notably hydrogen bonds. removed by filtration, and the filtrate was evaporated to
The ability to create molecular glass coordination compounds dryness in vacuo. The residue was purified by adding CH2Cl2
in a prescribed fashion may lead to interesting applications as (20 mL) and aqueous NaOH (1.0 M). The organic layer was
functional thin film materials. In particular, the current further extracted with aqueous NaOH (1.0 M, 3 × 30 mL). The
versatility and widespread use of non-glassy salen basic aqueous washings were recovered, combined, and
complexes24-30 suggests applications for their glass-forming neutralized with concentrated HCl to yield, after collection by
5
6
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8
9
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counterparts in
a
variety of areas (i.e., catalysis, filtration, washing with H2O and drying, compound 5 (0.332 g,
photoluminescence, magnetism, and sensors).
0.91 mmol, 91%) that required no further chromatographic
purification. FTIR (KBr/CH2Cl2) 3593, 3378, 3295, 3010, 2918,
2955, 2856, 1648, 1626, 1586, 1551, 1536, 1488, 1473, 1438,
1371, 1320, 1292, 1271, 1245, 1175, 1158, 1034, 986, 831,
793, 748, 670 cm-1; 1H NMR (400 MHz, DMSO-d6, 363 K) δ 9.44
(br s, 1 H), 7.57 (br s, 1 H), 7.35 (s, 2 H), 6.68 (s, 1 H), 2.86 (s, 3
H), 2.25 (s, 6 H) ppm; 13C NMR (75 MHz, DMSO-d6) δ 191.2,
168.4, 164.7, 164.1, 158.0, 138.7, 138.1, 131.5, 130.6, 125.4,
125.3, 122.5, 118.7, 21.6 ppm; HRMS (ESI, MNa+) calcd. for
C18H16ClNaN5O2 m/z: 392.0885, found: 392.0894
Experimental section
Materials and methods
4,6-Dichloro-2-mexylamino-1,3,5-triazine, was synthesized
according to literature procedures.20 All other reagents were
purchased from commercial sources and used without further
purification. All reactions were performed under ambient
atmospheric conditions unless otherwise noted. TLC plates
were purchased from SiliCycle. NMR spectra were recorded
using a Varian Oxford 300 MHz or a Bruker Avance 400 MHz
spectrometer at 298K unless otherwise noted. It must be
noted that both 1H and 13C NMR spectra of paramagnetic
complexes 8Mn, 8Fe, 8Co and 8Cu are reported, but the 1H signals
were heavily distorted and could not be appropriately
decoupled for proper peak integration. Moreover, while most
13C spectra were similar, in some cases, the peaks
corresponding to carbon atoms close to the metal center were
not visible. Decomposition analyses of molecular glasses were
obtained using a TGA Q50 thermogravimetric analyzer (TA
Instruments) at a heating rate of 10 °C/min under a nitrogen
atmosphere. Tg were recorded by DSC with a TA Instruments
Q20 calorimeter using a heating rate of 5 °C/min from ambient
temperatures to 250 °C, unless otherwise noted. Tg were
reported after an initial cycle of heating and cooling at 10
°C/min, and as the average of two trials. Infrared spectra were
recorded using a Thermo Scientific Nicolet iS10 spectrometer
as thin films deposited from CH2Cl2 solution onto KBr windows.
Synthesis of 2-mexylamino-4-methylamino-6-[(4-hydroxy-3-
formylphenyl)amino-1,3,5-triazine (1). To a round-bottomed
flask equipped with a magnetic stirrer and a water-jacketed
condenser were added 2-mexylamino-4-[(4-hydroxy-3-
formylphenyl)amino)-6-chloro-1,3,5-triazine 5 (6.03 g, 22.9
mmol) and a solution of aqueous methylamine (40 wt %
aqueous, 2.15 mL, 27.4 mmol) in THF (125 mL), then the
mixture was refluxed for 18 h. CH2Cl2 and aqueous HCl (1.0 M)
were added, and both layers were separated. The organic layer
was extracted with H2O and aqueous NaHCO3, dried over
Na2SO4, filtered, and the volatiles were thoroughly evaporated
under vacuum to yield 6.59 g of the title compound in
acceptable purity (18.1 mmol, 79%). Tg 81 °C; FTIR (KBr/CH2Cl2)
3379, 3274, 3227, 3098, 2950, 2920, 2854, 1661, 1636, 1582,
1561, 1517, 1483, 1429, 1397, 1322, 1272, 1184, 1040, 959,
884, 837, 771, 687, 649 cm-1; 1H NMR (400 MHz, DMSO-d6, 363
K) δ 9.97 (s, 1 H), 8.98 (br s, 1 H), 8.52 (br s, 1 H), 8.32 (s, 1 H),
8.11 (d, 1 H), 7.49 (m, 2 H), 7.37 (s, 2 H), 6.65 (br s, 1 H), 6.63
(s, 1 H), 2.90 (d, 3 H), 2.25 (s, 6 H) ppm; 13C NMR (75 MHz,
DMSO-d6) δ 192.1, 166.4, 164.6, 164.4, 164.2, 156.5, 140.6,
137.5, 132.9, 130.6, 123.5, 122.1, 121.2, 118.1, 117.5, 108.9,
27.7, 21.7, 21.6 ppm; HRMS (ESI, MH+) calcd. for C19H21N6O2
m/z: 365.1721, found: 365.1732.
Synthesis
Synthesis
of
2-mexylamino-4-[(4-hydroxy-3-
round-
formylphenyl)amino)-6-chloro-1,3,5-triazine (5).
A
bottom flask was charged with Pd(OAc)2 (0.011 g, 0.05 mmol),
2-(1,4-dioxa-5-cyclopentyl)-4-nitrophenol (2) (0.211 g, 1.00
mmol), and freshly distilled THF (5 mL). The flask was sealed
and purged with N2. While purging the flask with N2, an
aqueous KF solution (0.116 g, 2.00 mmol, in 2 mL degassed
H2O) was added via syringe. The N2 inlet was replaced with a
balloon filled with N2. PMHS (0.24 mL, 4 mmol) was slowly
Synthesis of Ligand 6. 2-Mexylamino-4-methylamino-6-[(4-
hydroxy-3-formylphenyl)amino]-1,3,5-triazine 1 (0.73 g, 2.0
mmol) was added in a round-bottomed flask which containing
10 mL ethanol. To the reaction mixture, an ethanolic solution
(10 mL) of 1,2-ethylenediamine (0.067 mL, 0.060 g, 1.0 mmol)
was added and the mixture was stirred at 80 °C for 2 h. Then,
the reaction mixture was filtered and the residue was washed
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with ethanol and reprecipitated from hexane/ethyl acetate to Synthesis of 8Mn. The preparation of this metal complex was
give 0.707 g (0.939 mmol, 94% yield) of ligand 6 as a yellow performed by adding Mn(OAc)2•2H2O (2.5 equiv., 296 mg, 1.71
solid. Tg 125 °C; FTIR (KBr) 3397, 3275, 3166, 3012, 2943, 2916, mmol) to a solution of ligand 8 (1.0 equiv., 350 mg, 0.685
View Article Online
DOI: 10.1039/C9NJ01159E
2863, 1882, 1635, 1579, 1515, 1429, 1395, 1273, 1174, 1129, mmol) in 5 mL of THF and 5 mL ethanol. The resulting brown-
1
1082, 1036, 974, 882, 836, 808, 685, 649 cm-1; H NMR (400 coloured mixture was refluxed for two hours with an air
MHz, DMSO-d6, 363 K) δ 9.97 (s, 1 H), 8.98 (br s, 1 H), 8.52 (br bubbler. LiCl (3 equiv., 87.0 mg, 2.06 mmol) was added to the
s, 1 H), 8.32 (s, 1 H), 8.11 (d, 1 H), 7.49 (m, 2 H), 7.37 (s, 2 H), mixture and the mixture refluxed for another three hours. The
6.65 (br s, 1 H), 6.63 (s, 1 H), 2.90 (d, 3 H), 2.25 (s, 6 H) ppm; mixture was poured into water to form a precipitate. The
13C NMR (75 MHz, DMSO-d6) δ 172.1, 171.3, 169.4, 160.8, precipitate was collected by filtration, washed with H2O, and
145.4, 142.3, 136.8, 128.3, 123.1, 122.8, 121.3, 64.3, 32.5, 26.4 allowed to dry to afford 240 mg of a brown complex 8Mn
ppm; HRMS (ESI, MH+) calcd. for C40H45N14O2 m/z: 753.3844, (0.425 mmol, 62% yield). Tg 176 °C; FTIR (KBr) 3384, 2951,
8
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found: 753.3867.
2887, 1767, 1723, 1654, 1619, 1536, 1514, 1461, 1443, 1424,
1378, 1339, 1289, 1239, 1178, 1116, 1057, 1036, 991, 929,
1
Synthesis of Ligand 7(R,R). To an ethanolic solution (10 mL) of 920, 868, 802 cm-1; H NMR (400 MHz, DMSO-d6, 363 K) δ
(1R, 2R)-(-)-diaminocyclohexane (0.22 g, 2.0 mmol) in a round- 8.16, 7.10, 6.33, 2.64, 1.98 ppm; 13C NMR (100 MHz, DMSO-d6)
bottomed flask equipped with a magnetic stirrer was added δ 160.8, 159.0, 158.3, 137.6, 134.6, 120.7, 115.2, 25.0, 19.0
dropwise a solution of 2-mexylamino-4-methylamino-6-[(4- ppm; HRMS (MALDI, M-Cl+) calcd. for C28H28MnN8O2 m/z:
hydroxy-3-formylphenyl)amino-1,3,5-triazine (1) (1.46 g, 4.0 563.1710, found: 563.1696.
mmol) in 10 mL of dry ethanol at ambient temperature. The
mixture was gradually heated to 80 °C and maintained for 3 Synthesis of 8Fe. A solution of FeCl3•6H2O (0.204 g, 0.754
hours at this temperature. The solvent was then evaporated mmol) in anhydrous EtOH (5 mL) was added to a solution of
under vacuum to afford a residue, which was reprecipitated ligand 8 (0.350 g, 0.685 mmol) in THF (5 mL) in a round-
from hexane/ethyl acetate to give 1.53 g (1.90 mmol, 95%) of bottomed flask equipped with a magnetic stirrer and a water-
the R,R enantiomer of ligand 7 as a yellow solid. Tg 131 °C; FTIR jacketed condenser. Triethylamine (0.220 mL, 0.159 g, 1.58
(KBr) 3733, 3709, 3646, 3564, 3400, 3283, 2926, 2856, 1632, mmol) was added, then the mixture was refluxed 30 min. The
1579, 1518, 1491, 1430, 1396, 1273, 1184, 1143, 1093, 1039, mixture was then poured into H2O, and the resulting
1
879, 837, 808, 783, 687, 651 cm-1; H NMR (400 MHz, DMSO- precipitate was collected by filtration, washed abundantly with
d6, 363 K): δ 9.97 (s, 1 H), 8.98 (br s, 1 H), 8.52 (br s, 1 H), 8.32 H2O and allowed to completely dry under air to give 0.311 g
(s, 1 H), 8.11 (d, 1 H), 7.49 (m, 2 H), 7.37 (s, 2 H), 6.65 (br s, 1 complex 8Fe (0.518 mmol, 76 %). Tg 196 °C; FTIR (KBr) 3390,
H), 6.63 (s, 1 H), 2.90 (d, 3 H), 2.25 (s, 6 H) ppm; 13C NMR (75 2953, 2888, 1766, 1722, 1625, 1536, 1512, 1461, 1444, 1422,
MHz, DMSO-d6): δ 166.5, 165.5, 164.6, 156.2, 155.9, 141.1, 1377, 1340, 1292, 1239, 1179, 1116, 1058, 1036, 990, 929,
140.6, 139.6, 137.5, 137.4, 132.1, 123.6, 118.5, 118.3, 118.1, 920, 870, 801, 759 cm-1; 1H NMR (400 MHz, DMSO-d6, 363 K) δ
117.6, 116.4, 72.1, 33.8, 33.4, 33.1, 30.9, 27.7, 25.0, 24.9, 24.6, 9.08, 7.55-6.90 3.3-2.27 ppm; 13C NMR (100 MHz, DMSO-d6) δ
24.2, 21.6 ppm; HRMS (ESI, MNa+) calcd. for C44H50NaN14O2 167.6, 164.9, 163.0, 162.6, 155.3, 139.5, 136.4, 130.4, 122.5,
m/z: 829.4133, found: 829.4160.
116.9, 26.7, 20.7 ppm; HRMS (MALDI, M-Cl+) calcd. for
C28H28FeN8O2 m/z: 564.1679, found: 564.1690.
Synthesis of Ligand 8. To a solution of 2-mexylamino-4-
methylamino-6-[(4-hydroxy-3-formylphenyl)amino]-1,3,5-
Synthesis of 8Co. A solution of Co(OAc)2•4H2O (0.498 g, 2.00
triazine 1 (0.73 g, 2.0 mmol) and salicylaldehyde (0.209 mL, mmol) in anhydrous EtOH (5 mL) was added to a solution of
0.244 g, 2.0 mmol) in 20 mL absolute ethanol was added ligand 8 (0.509 g, 1.00 mmol) in THF (10 mL) in a round-
dropwise a solution of ethylenediamine (0.134 mL, 0.120 g, 2.0 bottomed flask equipped with a magnetic stirrer and a water-
mmol) in 10 mL absolute ethanol. The solution mixture was jacketed condenser. The mixture was degassed by sparging
refluxed for 2h, filtered while hot and the excess solvent with N2 for 10 min, then the mixture was refluxed 18 h under
removed in vacuo to afford
a residue, which was N2 atmosphere. After cooling down to ambient temperature,
reprecipitated from hexane/ethyl acetate to give 0.949 g (1.86 the mixture was poured in H2O, then the precipitate was
mmol, 93%) of ligand 8 as a yellow solid. Tg 78 °C; FTIR collected by filtration, briefly washed with H2O, and allowed to
(KBr/CH2Cl2) 3400, 3275, 2954, 2930, 1614, 1557, 1517, 1493, dry under air to yield 0.374 g complex 8Co (0.659 mmol, 66 %).
1429, 1397, 1319, 1273, 1183, 1159, 1142, 1116, 1104, 975, Tdec 170 °C; FTIR (KBr) 3392, 2952, 2888, 1769, 1769, 1723,
883, 839, 746, 686, 649 cm-1; 1H NMR (400 MHz, DMSO-d6, 363 1623, 1513, 1460, 1443, 1422, 1376, 1340, 1281, 1262, 1239,
1
K): δ 9.97 (s, 1 H), 8.98 (br s, 1H), 8.52 (br s, 1H), 8.32 (s, 1H), 1177, 1116, 1058, 1036, 991, 929, 920, 869, 801, 759 cm-1; H
8,11 (d, 1H), 7.49 (m, 2H), 7.37 (s, 2H), 6.65 (br s, 1H), 6.63 (s, NMR (400 MHz, DMSO-d6, 363 K) δ 9.08, 7.64, 6.73, 3.71, 3.02,
1H), 2.90 (d, 3H), 2.25 (s, 6H) ppm; 13C NMR (75 MHZ, DMSO- 2.36 ppm; 13C NMR (75 MHz, DMSO-d6) δ 167.4, 166.1, 164.1,
d6): δ 166.7, 164.7, 164.4, 152.1, 143.1, 142.8, 141.1, 140.7, 160.4, 140.2, 137.1, 134.2, 129.4, 125.1, 123.0, 122.6, 117.5,
140.6, 137.5, 134.7, 132.5, 128.2, 123.6, 119.7, 119.1, 118.7, 117.2, 114.9, 57.7, 27.2, 21.2 ppm; HRMS (MALDI, M+) calcd.
118.2, 117.6, 117.1, 115.7, 112.5, 27.7, 21.6 ppm; HRMS (EI, for C28H29CoN8O2 m/z: 568.1740, found: 568.1749.
MH+) calcd. for C25H24N8O m/e: 425.5149, found 425.5241.
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Complexes 8Ni and 8Cu were synthesized according to the same CDCl3) δ 13.34 (s, 0.3 H), 13.24 (s, 0.7 H), 8.41 (s, 0V.6iewHA)r,ti8cl.e2O3nl(inse,
procedure as analogue 8Co from the respective acetates 0.4 H), 7.21-7.31 (m, 2 H), 6.77-6-96 (m, 2 H), 3.23-3.31 (m, 0.6
(Ni(OAc)2•4H2O, Cu(OAc)2•xH2O) except that the reactions H), 2.83 (q, 1 H), 2.21-2.29 (m, 0.4 H), 1.77-1.91 (m, 2 H), 1.51-
DOI: 10.1039/C9NJ01159E
were run under ambient atmosphere:
1.77 (m, 2 H), 1.11-1.50 (m, 4 H) ppm.
To an ethanol solution (20 mL) of the resulting chiral
Synthesis of 8Ni. Yield: 78 %; Tg 133 °C; FTIR (KBr) 3375, 2952, monoimine intermediate (0.437 g, 2 mmol) was added
2886, 1765, 1667, 1620, 1535, 1511, 1460, 1424, 1378, 1337, dropwise 2-mexylamino-4-methylamino-6-[(4-hydroxy-3-
1311, 1278, 1239, 1179, 1116, 1044, 991, 921, 869, 849, 802, formylphenyl)amino 1,3,5-triazine 1 (0.728 g, 2.00 mmol) in 20
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780, 762 cm-1 ; H NMR (400 MHz, DMSO-d6, 363 K) δ 8.38 (s, mL of ethanol at ambient temperature. The mixture was
1H), 8.32 (s, 1H), 7.80 (m, 1H), 7.72 (m, 1H), 7.55 (s, 1H), 7.44 gradually heated to 80 °C and then this temperature was
(m, 1H), 7.36 (s, 2H), 7.22 (m, 1H), 7.16 (t, 1H), 6.72 (m, 1H), maintained for 4 hours. Upon the removal of the solvent and
6.68 (m, 1H), 6.59 (s, 1H), 6.49 (m, 1H), 6.44 (m, 1H), 3.42 (s , cooling, a yellow precipitate was collected and reprecipitated
3H), 2.87 (m, 3H), 2.24 (s, 6H) ppm; 13C NMR (75 MHz, DMSO- from ethanol to give 1.07 g of chiral ligand 9 (1.71 mmol, 85
d6) δ 166.0, 164.1, 163.8, 162.4, 162.2, 160.4, 140.2, 139.1, %). Tg 99 °C; FTIR (KBr/CH2Cl2) 3400, 3279, 3055, 3011, 2930,
137.0, 133.4, 132.7, 129.2, 127.3, 124.8, 122.9, 120.2, 119.6, 2857, 1631, 1579, 1517, 1492, 1430, 1396, 1275, 1185, 1144,
119.1, 117.5, 114.2, 57.9, 27.2, 21.1 ppm; HRMS (MALDI, M+) 1092, 1041, 976, 940, 881, 837, 808, 783, 756, 736, 687, 663
1
calcd. for C28H29N8NiO2 m/z: 567.1761, found: 567.1785.
cm-1; H NMR (400 MHz, DMSO-d6, 363 K) δ 9.97 (s, 1 H), 8.98
(br s, 1 H), 8.52 (br s, 1 H), 8.32 (s, 1 H), 8.11 (d, 1 H), 7.49 (m, 2
Synthesis of 8Cu. Yield: 84 %; Tg 159 °C; FTIR (KBr) 3379, 2949, H), 7.37 (s, 2 H), 6.65 (br s, 1 H), 6.63 (s, 1 H), 2.90 (d, 3 H), 2.25
2886, 1770, 1722, 1631, 1602, 1521, 1460, 1425, 1379, 1339, (s, 6 H) ppm; 13C NMR (75 MHz, DMSO-d6) δ 166.5, 165.5,
1301, 1239, 1176, 1116, 1057, 1036, 991, 929, 920, 861, 801, 165.5, 165.5, 164.6, 164.3, 160.8, 155.9, 140.6, 137.5, 132.7,
1
762 cm-1; H NMR (400 MHz, DMSO-d6, 363 K) δ 8.29, 8.04, 132.1, 123.6, 119.0, 118.9, 118.3, 118.1, 116.8, 116.4, 71.8,
7.29, 6.60, 6.35, 3.62, 2.80, 2.26 ppm; 13C NMR (75 MHz, 33.1, 33.0, 27.7, 24.1, 21.6 ppm; HRMS (ESI, MH+) calcd, for
DMSO-d6) δ 165.9, 163.7, 140.2, 137.2, 129.3, 123.2, 117.6, C32H37N8O2 m/z: 565.3034, found: 565.3057.
114.6, 67.0, 27.2, 21.3 ppm; HRMS (MALDI, M+) calcd. for
C28H29CuN8O2 m/z: 572.1704, found: 572.1727.
Synthesis of 9Zn. A solution of ZnCl2 (20.0 mg, 0.215 mmol) in
anhydrous EtOH (2 mL) was added to a solution of ligand
Synthesis of 8Zn. A solution of ZnCl2 (150 mg, 0.110 mmol) in 9(R,R) (100 mg, 0.196 mmol) in THF (2 mL) in a round-
anhydrous EtOH (2 mL) was added to a solution of ligand 8 bottomed flask equipped with a magnetic stirrer and a water-
(56.0 mg, 0.100 mmol) in THF (2 mL) in a screw-cap vial jacketed condenser. NEt3 (63.0 mL, 0.451 mmol) was added
equipped with a magnetic stirrer. NEt3 (30.0 μL, 0.230 mmol) and the yellow mixture was refluxed for 30 min under ambient
was added and the yellow-coloured mixture was heated to 60 atmosphere. After cooling down to ambient temperature, the
°C for 30 min under ambient atmosphere. After cooling to mixture was poured into H2O, then the precipitate was
ambient temperature, the mixture was poured into H2O, then collected by filtration, briefly washed with H2O, and allowed to
the precipitate was collected by filtration, briefly washed with dry under air to yield 93.4 mg of the yellow complex 9Zn (0.149
H2O, and allowed to dry under air to yield 44.1 mg of the mmol, 76%). Tg = 165 °C; FTIR (KBr) 3381, 2948, 2885, 1765,
yellow solid complex, 8Zn (77 μmol, 77%). Tg 146 °C; FTIR (KBr) 1723, 1612, 1539, 1516, 1491, 1460, 1443, 1423, 1402, 1377,
3388, 2951, 2887, 2733, 1768, 1723, 1620, 1512, 1485, 1460, 1341, 1315, 1299, 1277, 1238, 1178, 1116, 1043, 991, 929,
1443, 1422, 1376, 1340, 1278, 1238, 1178, 1116, 1058, 1036, 920, 869, 849, 803 cm-1; 1H NMR (400 MHz, DMSO-d6, 363 K) δ
1
991, 929, 920, 870, 801, 761 cm-1; H NMR (400 MHz, DMSO- 8.23 (s, 2H), 7.34 (m, 5H), 7.23 (d, 1H), 7.13 (t, 1H), 6.60 (m,
d6, 363 K) δ 8.44 (s, 1H), 8.34 (s, 1H), 7.37 (m, 4H), 7.16-7.07 2H), 6.55 (d, 2H), 6.42 (t, 2H), 3.19 (s, 2H), 2.83 (s, 3H), 2.19 (s,
(m, 1H), 6.92-6.81 (m, 1H), 6.61-6.56 (m, 2H), 3.73 (s, 3H), 2.83 6H), 1.91 (s, 2H), 1.41-1.39 (m, 4H) ppm; 13C NMR (75 MHz,
(s, 3H), 2.20 (s, 6H) ppm; 13C NMR (75 MHz, DMSO-d6) δ 171.5, DMSO-d6) δ 171.3, 167.8, 166.6, 165.1, 164.8, 140.8, 139.7,
168.5, 168.3, 166.6, 164.6, 140.9, 137.5, 133.2, 129.1, 127.9, 137.5, 135.9, 133.2, 129.1, 125.8, 125.4, 123.4, 123.1, 122.6,
123.4, 123.2, 122.7, 119.8, 118.3, 117.9, 114.3, 56.3, 29.5, 119.8, 118.3, 118.0, 112.6, 65.0, 35.0, 30.6, 28.2, 27.7, 24.3,
27.8, 21.7 ppm; HRMS (MALDI, M+) calcd. for C28H29N8O2Zn 21.7 ppm; HRMS (MALDI, M+) calcd. for C32H35N8O2Zn m/z:
m/z: 573.1699, found: 573.1715.
627.2169, found: 627.2183.
Synthesis of ligand 9(R,R). Salicylaldehyde (0.712 mL, 0.830 g, Synthesis of ligand 10. Solutions of salicylaldehyde (1.05 mL,
6.80 mmol) in dichloromethane (50 mL) was added dropwise 1.22 g, 10.0 mmol) and o-phenylenediamine (1.08 g, 10.0
to a vigorously stirred solution of (1R,2R)-diaminocyclohexane mmol) in ethanol (20 mL each) were mixed and refluxed for
(0.78 g, 6.8 mmol) in dichloromethane (150 mL) containing 3 Å about 4 h. The reaction mixture was evaporated to a small
molecular sieves at 0 °C. The complete addition took volume and left to cool. The resulting monoimine intermediate
approximately 5 hours, and then the reaction mixture was precipitated on cooling and was then collected by filtration,
stirred for 5 h without interruption. Upon filtration, the filtrate washed with ethanol and recrystallized from ethanol. The
was evaporated under vacuum at 60 °C to give a pale-yellow purity of the intermediate was monitored on TLC using ethyl
creamy solid, 1.43 g (6.56 mmol, 95 %).36 1H NMR (300 MHz, acetate/petroleum ether 1:1 to give the corresponding
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monomine as a brown solid (90% yield).37 1H NMR (300 MHz,
CDCl3) δ: 12.83 (s, 1 H), 8.63 (s, 1 H), 7.47-6.77 (m, 8 H), 3.79
(br, 2 H).
3
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K. Mori and H. Yamashita, Chem. - Eur. J., 2016, 22, 11122-
View Article Online
DOI: 10.1039/C9NJ01159E
11137.
B. I. Kharisov, O. V. Kharissova, A. Vazquez Dimas, I. Gomez
De La Fuente and Y. Pena Mendez, J. Coord.
Chem., 2016, 69, 1125-1151.
E. Guibal, T. Vincent and R. Navarro, J. Mater. Sci.,
2014, 49, 5505-5518.
J. Choi, H. T. Kwon and H.-K. Jeong, MRS Adv., 2017, 2, 2497-
2504.
M. Cavallini, M. Facchini, C. Albonetti and F. Biscarini, Phys.
Chem. Chem. Phys., 2008, 10, 784-793.
A solution of 2-mexylamino-4-methylamino-6-[(4-hydroxy-3-
formylphenyl)amino]-1,3,5-triazine 1 (0.364 g, 1.00 mmol) and
salicylaldehyde 2-aminophenyl monoimine (0.212 g, 1.00
mmol) in dry ethanol (10 mL) was refluxed for 3 h. The solvent
was evaporated under vacuum to afford a residue, which was
reprecipitated from hexane/ethyl acetate to give 477 mg
(0.817 mmol, 81%) of the ligand 10 as a red solid. Tg = 69 °C;
FTIR (KBr/CH2Cl2) 3392, 3274, 3221, 3061, 2959, 2918, 1614,
1572, 1514, 1487, 1428, 1396, 1320, 1299, 1275, 1213, 1184,
1152, 1130, 1116, 1104, 1035, 976, 939, 907, 883, 840, 750,
685, 646 cm-1; 1H NMR (400 MHz, DMSO-d6, 363 K) δ 9.97 (s, 1
H), 8.98 (br s, 1 H), 8.52 (br s, 1 H), 8.32 (s, 1 H), 8.11 (d, 1 H),
7.49 (m, 2 H), 7.37 (s, 2 H), 6.65 (br s, 1 H), 6.63 (s, 1 H), 2.90
(d, 3 H), 2.25 (s, 6 H) ppm; 13C NMR (75 MHz, DMSO-d6) δ
166.6, 165.9, 164.5, 160.8, 156.1, 142.8, 140.6, 137.5, 133.9,
132.9, 132.4, 128.7, 123.6, 120.20, 119.9, 119.5, 119.1, 118.1,
117.1, 116.8, 150, 27.7, 21.6 ppm; HRMS (ESI, MNa+) calcd, for
C32H30NaN8O2 m/z: 581.2384, found: 581.2396.
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Synthesis of 10Zn. Compound 10Zn was synthesized according
to the same procedure as analogue 8Co from ligand 10 and
Zn(OAc)2 • 2H2O. Yield: 60 %; Tg 167 °C; FTIR (KBr) 3389,
2950.89, 2887, 1768, 1723, 1614, 1514, 1484, 1460, 1444,
1422, 1378, 1340, 1317, 1279, 1239, 1178, 1116, 1058, 1036,
1
991, 930, 921, 870, 801, 761 cm-1; H NMR (400 MHz, DMSO-
d6, 363 K) δ 8.96 (s, 1H), 8.85 (s, 1H), 8.41 (s, 1H), 8.30 (s, 1H),
7.86 (m, 1H), 7.79 (s, 1H), 7.73 (s, 1H), 7.49 – 7.47 (d, 1H), 7.39
(m, 5H), 7.25 (t, 2H), 6.73 (t, 2H), 6.56 (s, 1H), 6.52 (t, 1H), 6.45
(m, 1H), 2.89 (s, 3H), 2.21 (s, 7H) ppm; 13C NMR (75 MHz,
DMSO-d6) δ 172.2, 169.0, 166.0, 164.2, 162.7, 162.1, 140.2,
139.3, 137.0, 136.1, 134.2, 130.5, 127.1, 127.1, 126.0, 124.8,
123.0, 122.9, 122.6, 119.3, 117.9, 117.5, 116.4, 116.2, 112.9,
27.2, 21.1 ppm; HRMS (MALDI, M+) calcd. for C32H31N8O2Zn
m/z: 621.1699, found: 621.1702.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
The authors would like to thank the Canadian Defence
Academy Research Programme (CDARP) from RMC for
funding. The authors would also like to thank Dr. Philippe
Venne for mass spectrometry and Mr. Bob Whitehead for X-
ray diffraction analyses.
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Glass
Glass
Glass
HN
HN
HN
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N
N
N
N
N
N
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HN
N
NH
HN
N
NH
HN
N
NH
OH
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CHO
O
O
N
N
OH
OH
N
N
M
Complex
Ligand
Precursor