Cyclotriphosphazenes as Scaffolds for the Synthesis of Metallomesogens

Article abstract of DOI:10.1021/acs.inorgchem.0c00124

(Amino)cyclotriphosphazenes have been used as new scaffolds for the synthesis of silver(I) metallomesogens. Two cyclotriphosphazenes, [N₃P₃(NHCy)₆] (phos-1) and nongem-trans-[N₃P₃(NHCy)₃(NM

Full text of DOI:10.1021/acs.inorgchem.0c00124

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Cyclotriphosphazenes as Scaffolds for the Synthesis of
Metallomesogens
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́
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Josefina Jimenez,* Jose Antonio Sanz, Jose Luis Serrano, Joaquín Barbera, and Luis Oriol
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ABSTRACT: (Amino)cyclotriphosphazenes have been used as new scaffolds for the synthesis of
silver(I) metallomesogens. Two cyclotriphosphazenes, [N3P3(NHCy)6] (phos-1) and nongem-
trans-[N3P3(NHCy)3(NMe2)3] (phos-2), were reacted with the silver complex having a pro-
mesogenic ligand, [Ag(OTf)L] (L = CNC6H4{OC(O)C6H2(3,4,5-(OC10H21)3)}-4; OTf =
OSO2CF3), in different molar ratios, 1:1, 1:2, or 1:3, to give two series of cationic
metallophosphazenes, [N3P3(NHCy)6{AgL}n](TfO)n (phos-1.n) and nongem-trans-
[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (phos-2.n) with n = 1, 2, or 3. The chemical structure
of these compounds, deduced from spectroscopic techniques, was in accordance with coordination
of the silver fragments “AgL” to nitrogen atoms of the phosphazene ring, whereby their number n
depends on the molar ratio used. Despite the presence of the bulky substituents on the core N
atoms, cyclotriphosphazenes coordinated to three “AgL” units exhibited mesomorphism at room
temperature. The mesophase was characterized as columnar hexagonal according to the optical
microscopy and X-ray diffraction studies. A model based on an intermolecular association in pairs of
the metallocyclotriphosphazenes having three AgL units has been proposed in order to explain the
mesomorphic columnar arrangement in these materials. Starting silver complex, [Ag(OTf)L], also exhibited a columnar hexagonal
mesophase at room temperature.
triphosphazenes provide new possibilities to the design of
metallomesogens by using as a core with three nitrogen atoms
able to coordinate metallic entities, e.g., silver(I) derivatives,
and with additional substitution on the P atoms.
1. INTRODUCTION
Metal-containing liquid crystals, also known as metallomes-
ogens, can expand the properties of conventional liquid crystals
usually based on totally organic materials.1 The presence of
metal atoms opens up the possibility of new structures in the
design of liquid crystals derived from the metal geometries of
organometallic and coordination compounds. Besides, metal
entities modify the physical properties of conventional liquid
crystals based on organic materials, such as magnetic, electric,
or optical properties. A large variety of complexes have been
described as mesomorphic so far using different metal entities.
Silver(I) derivatives are of particular interest in the field of
liquid crystals due to ability to yield ionic liquid crystals and
their structural motifs compatible with the mesomorphism.2
Stilbazole derivatives have been most widely used ligands for
the preparation of both calamitic and columnar Ag(I)
mesomophic materials3a from the pioneering work by Bruce
and co-workers.3b Although to far less an extent, isocyanides
have been also described as versatile ligands for the preparation
of mesogenic ionic Ag(I) complexes either having calamitic or
columnar mesomorphism depending on the number of
peripheral aliphatic chains of the ligands.4 The mesomorphic
arrangement of functional ligands connected with the
particular properties introduced by silver atoms has recently
been applied to the preparation of ion-conductive functional
materials5 or organic semiconductors, among other applica-
tions.6 Nevertheless, the silver(I) liquid crystalline complexes
described so far have a conventional structure. Cyclo-
Phosphazenes, [NPR2], are an important type of inorganic
compounds, whose properties can be tailored by the choice of
appropriate side groups on phosphorus, R.7 They are usually
prepared by nucleophilic substitution reactions that involve the
use of halophosphazene, [NPCl2], cyclic trimers, or high
polymers as substrates for reactions with alkoxides, aryloxides,
or amines.7,8 In addition, with few restrictions, organic side
groups incorporated into a phosphazene can themselves be
modified by exposure to reagents that introduce additional
functionality,9 as has been recently reviewed.10 Thus, trimers
or polymers with all the chloro atoms replaced by pro-
mesogenic units have been prepared in an effort to obtain
liquid crystalline materials.11 Specifically, cyclotriphosphazenes
have proved to be useful as a multiarmed central core upon
which mesogenic units have been linked to the phosphorus
atoms to give supermolecular liquid crystals.12 In this regard,
Received: January 13, 2020
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we have reported several series of these nonconventional liquid
crystals with the pro-mesogenic units directly attached to the
ring phosphorus atoms,13 whose mesomorphic properties
strongly depend on a suitable volume balance between the
rigid core and the alkyl chains in the pro-mesogenic group
ranging from calamitic to discotic and to cubic mesomorphism
when the number of terminal alkyl chains increases. Calamitic
mesomorphism is promoted by monosubstituted units (e.g.,
having one terminal alkyl chain or monocatenar), and this
behavior was explained in terms of the model shown in Chart
1a.13a,b,14 Columnar or cubic phases resulted from the
known, both with the metal coordinated to peripheral donor
atoms17 and coordinated to the backbone N atoms.18 We have
also contributed to this field by reporting metallocyclo- and
polyphosphazenes containing gold or silver coordinated to
exocyclic 4-oxypyridine groups and their thermolytic trans-
formation into nanostructured materials or into metallic micro-
and nanostructures deposited on silicon and silica surfaces.19
We have also recently explored the reactivity of the multisite
(amino)cyclotriphosphazene ligands with the silver complexes
[Ag(OTf)L] (L = PPh3 or PPh2Me; OTf = OSO2CF3) and
obtained two series of the cationic metallophosphazenes,
[N3 P3(NHCy)6 {AgL}n ](TfO)n and nongem-trans-
[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (n = 2 or 3, L =
PPh3 or PPh2Me), in which the silver moieties “AgL” are
coordinated to the nitrogen atoms of the phosphazene ring
(see Chart 2) and which have outstanding biological
properties.20 However, to the best of our knowledge, there
are no reports of metallophosphazenes with liquid crystalline
properties.
Chart 1. Schematic Models for Calamitic Structure of
Cyclophosphazenes and Star-Shaped Structure of
a
Cyclophosphazenes with Polycatenar Moieties
Herein, the reactivity of (amino)cyclotriphosphazene ligands
has been explored in order to obtain new silver(I) metal-
lomesogens. Two cyclotriphosphazenes were used, a single-
substituent trimer having six cyclohexylamine units linked to
the P atoms, [N3P3(NHCy)6] (phos-1), and a mixed-
substitutent trimer having three cyclohexylamino and three
dimethylamino units linked to the P atoms in a nongeminal-
trans arrangement (i.e., 2,4,6-trans-[N3P3(NHCy)3(NMe2)3]
(phos-2); see Chart 3a). A strategy similar to the one used to
obtain derivatives shown in Chart 2 was performed but this
time with a starting silver complex having a pro-mesogenic
ligand, [Ag(OTf)L] (L = CNC6H4{OC(O)C6H2(3,4,5-
(OC10H21)3)}-4; OTf = OSO2CF3) (see Chart 3b) instead
of a phosphane ligand. Thus, two series of cationic metal-
lophosphazenes have been obtained, [N3P3(NHCy)6{AgL}n]-
( T f O ) n ( p h o s - 1 . n ) a n d n o n g e m - t r a n s -
[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (phos-2.n) with n =
1, 2, or 3, in which the silver fragments “AgL” are coordinated
to nitrogen atoms of the phosphazene ring. The thermal and
mesomorphic properties of this new series of cyclophospha-
zenes are also reported here in an effort to continue the
exploration of these nonconventional structures.
a
(a) Calamitic structure of cyclophosphazenes with monocatenar
moieties, which point upwards and downwards regarding the
cyclotriphosphazene ring; (b) the star-shaped structure of cyclo-
phosphazenes with polycatenar moieties, which arrange themselves
parallel to the cyclotriphosphazene ring (represented as a black circle)
in two levels (mesogens in the upper level indicated with a darker
color and in lower level with a lighter color).
incorporation of polycatenar units, which promote from a
hexagonal columnar mesophase to a cubic mesophase upon
increasing the number of chains in the periphery of the system.
The columnar mesomorphism was explained in terms of the
model shown in Chart 1b.13
Phosphazenes, trimers, or polymers, can also be used as
scaffolds for the design and construction of a variety of
ligands,15,16 to coordinate to metals. The facile substitution of
P−Cl bonds in cyclic trimer or polymer allows ready
construction of phosphazenes carrying additional peripheral
donor functions giving a library of multisite coordination
ligands. Indeed, the backbone nitrogen atoms have sufficient
basicity to coordinate to metals depending on the electronic
properties of the exocyclic substituents at phosphorus. Alkyl,
aryl, and primary and secondary organo amino substituents
enhance the donor ability of backbone N atoms.16c Silver
derivatives of phosphazenes (cyclic or polymers) are also
2. RESULTS AND DISCUSSION
2.1. Synthesis and Characterization of the Metal-
lophosphazenes. The isocyanide ligand and the starting
silver complex, [Ag(OTf)L], used in this work, were prepared
according to literature methods,4b,21,22 as shown in Scheme 1;
see the Experimental Section for details of [Ag(OTf)L].
The synthesis of metallophosphazenes was approached by
complexation of the donor nitrogen atoms of an (amino)-
cyclophosphazene ring. The reaction of phos-1 or phos-2 with
Chart 2. Compounds Obtained in the Reaction of [N3P3(NHCy)3(NRR′)3] (NRR′ = NHCy or NMe2) with [Ag(OTf)L] (L =
PPh3 or PPh2Me) in a Molar Ratio (a) 1:2 (b) 1:3
B
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a
Chart 3. Compounds Used in This Work
a
(a) (Amino)cyclotriphosphazene trimers used as ligands in this work and (b) starting silver complex used in this work, [Ag(OTf)L].
Scheme 1. Synthesis of the Isocyanide Ligand and the Starting Silver Complex, [Ag(OTf)L]
Scheme 2. Synthesis of the New Metallophosphazenes
C
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a
Table 1. 31P{1H} NMR Spectroscopic Data for Silver Complexes with phos-1 at Room Temperature and at −80°C
b
b
δ[N−P−NAg]
δ[AgN−P−NAg]
b
c
c
compound
spin system
T, solvent
δ[N−P−N]
[2JP−P
]
[2JP−P
]
d
phos-1
A3
RT, CDCl3
14.44 (s)
phos-1.1
AB2
RT, CD2Cl2
15.19 (s, br)
−80 °C, CD2Cl2
RT, CDCl3
−80 °C, CD2Cl2
RT, CDCl3
14.09 (“t”)
15.98 (“d”) [48.2]
13.58 (“d”)
d
phos-1.2
AB2
AB2
A3
16.71 (s, br)
17.18(“t”) [35.6]
e
e
[N3P3(NHCy)6{AgPPh3}2](TfO)2
phos-1.3
16.90 (s, br)
−80 °C, (CD3)2CO
RT, CDCl3
13.23(“d”)
17.54(“t”) [36.3]
18.97 (s)
d
−80 °C, CD2Cl2
18.35 (s)
[N3P3(NHCy)6{AgPPh3}3](TfO)3
A3
RT, CDCl3
18.38 (s)
a
b
c
d
Compounds [N3P3(NHCy)6{AgPPh3}n](TfO)n (n = 2 or 3) have been included for comparison.20 Values in ppm. Values in Hz. The data in
e
CD2Cl2 at RT, which are given in the Experimental Section, are very similar to those in CDCl3. See ref 20. [N3P3(NHCy)6{AgPPh3}](TfO) with
only a silver fragment, “AgPPh3”, is not known. The reaction of [N3P3(NHCy)6] with [Ag(OTf)PPh3] in molar ratio 1:1 evolved with the loss of
the ligand, PPh3, and formation of [N3P3(NHCy)6Ag(TfO)]n. That is why we have been unable to compare the signal of phos-1.1 with other
similar compounds.
the silver complex [Ag(OTf)L] (L = CNC6H4{OC(O)-
C6H2(3,4,5-(OC10H21)3)}-4; OTf = OSO2CF3), in dichloro-
methane and in different molar ratios, 1:1, 1:2, or 1:3, led to
two series of cationic metallophosphazenes,
[N3P3(NHCy)6{AgL}n](TfO)n (phos-1.n) and nongem-trans-
[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (phos-2.n). In all
metallophosphazenes obtained, the silver fragments “AgL”
are coordinated to nitrogen atoms of the phosphazene ring,
whereby their number n depends on the molar ratio used (see
Scheme 2).
presence of ionic trifluoromethanesulfonate was clearly
confirmed by single-crystal X-ray structural analyses.20 In
addition, the conductivity of phos-1.1 and phos-2.1 was
measured in dichloromethane. The molar conductivity values
(ΛM) of both compounds were 12 and 15 ohm−1 cm2 mol−1,
respectively, which are similar to those of silver 1:1 electrolytes
in literature.22 A single peak at approximately −78 ppm
appears in the 19F NMR spectra for all synthesized metal-
lophosphazenes. The bands of the characteristic phosphazene
absorptions in the IR spectra, such as PN and C−N (at
1186 and 1177 cm−1 in phos-1 and at 1180, 1171, and 1140
cm−1 in phos-2), change after coordination of the metal, as
also previously observed in other poly- or cyclophosphazenes
with silver coordinated to the core nitrogen atoms.18c,20
However, new bands corresponding to these peak frequencies
could not be assigned in the new metallophosphazenes because
of the overlap with CF3, SO3, and isocyanide vibrational
modes. The bands in the 3000−3400 cm−1 region, which are
assigned to the N−H stretching, are also different from those
of the starting phosphazenes. On complexation, only one band
at approximately 3300 cm−1 is observed for all complexes,
which can be attributed to the disruption of the hydrogen
bonding of N−H groups.18c The IR spectra also show the
ν(CO) and ν(CN) absorptions from the isocyanide ligand.
ν(CN) absorptions appear at higher wavenumbers (ca. 60
cm−1) than in the free isocyanide, as observed in other
isocyanide silver complexes4b,21a and in the starting product
itself, [Ag(OTf)L]. This shift is due to two factors, the σ-
donation of the antibonding carbon lone pair to metal and the
π-backbonding from metal d orbital to the π* ligand orbitals.21
Besides, in our series of compounds, phos-1.n and phos-2.n
(especially in phos-1.n) this ν(CN) absorption shifts slightly
to higher wavenumbers with the rise in the number of silver
atoms, which indicates a rise of the σ-donation from isocyanide
ligands as a consequence of a lower σ-donation from the
phosphazene as the silver atoms increase.
All the metallophosphazenes were obtained in high yield and
are soluble in organic solvents such as dichloromethane,
chloroform, or hexane and only slightly soluble in acetone or
ethanol. All these compounds and the starting product itself,
[Ag(OTf)L], were characterized by elemental analysis, IR, 1H,
13C{1H}, and 31P{1H} NMR spectroscopy, and MALDI-TOF
mass spectrometry. The characterization data are given in the
Experimental Section and are consistent with the formulas and
structure indicated and, specifically, with the coordination of
metals to the backbone nitrogen atoms, as will be mentioned
later in detail. All data have been compared with those
observed for the similar complexes [N3P3(NHCy)6{AgL}n]-
(TfO)n or nongem-trans-[N3P3(NHCy)3(NMe2)3{AgL}n]-
(TfO)n (n = 2 or 3; L = PPh3 or PPh2Me) mentioned before,
which were characterized by single-crystal X-ray diffraction,
thereby allowing key bonding information to be obtained and
in which metals are coordinated to the ring nitrogen atoms.20
IR spectra clearly evidence the coordination of the metal
fragments “AgL” to phos-1 or phos-2, showing absorptions
attributable to trifluoromethanesulfonate (triflate) units and to
the isocyanide ligand, which are all shifted from those in the
starting complex [Ag(OTf)L]. The triflate peaks, which could
in principle be used to distinguish covalent and ionic
trifluoromethanesulfonate,23 are not very useful because an
unambiguous assignment is hindered by the overlap of CF3,
SO3, and isocyanide vibrational modes.19a,22 However, all
complexes have very similar bands in shape and position in the
stretching region of the triflate (1280−1000 cm−1, ν[SO3(E)],
ν[SO3(A1)], ν [CF3(A1)], and ν [CF3(E)]) (see the
Experimental Section). These bands are also similar to those
observed for the complexes [N3P3(NHCy)6{AgL}n](TfO)n or
nongem-trans-[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (n = 2
or 3; L = PPh3 or PPh2Me) mentioned before, for which the
1
The 31P{1H} and H NMR spectra in solution are also
consistent with the coordination of the metal fragments to the
ring nitrogen atoms. The signals observed for complexes with
single-substituent trimer phos-1 in their 31P{1H} NMR spectra
at room temperature (RT) are collected in Table 1. A single
peak, shifted downfield from the peak of parent phosphazene,
is shown by the phosphazene phosphorus atoms in all
D
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Figure 1. 31P{1H} NMR spectra of compound phos-1.1 in CD2Cl2 at RT and (b) at −80 °C.
a
1
Table 2. H NMR Spectroscopic Data for Silver Complexes with phos-1 at Room Temperature
compound
δ(CNC6H4O)
δ(C6H2)
δ(OCH2)
δ(NH)
δ(N−CH)
δ(CH2)
δ(CH3)
7.45 (“d”, 8.9 Hz, 2H); 7.24
(“d”, 8.9 Hz, 2H)
7.63 (“d”, 8.9 Hz, 2H); 7.36
(“d”, 8.9 Hz, 2H)
7.37
4.06 (“t”, 6.6 Hz, 2H); 4.03
(“t”, 6.6 Hz, 4H)
4.07 (“t”, 6.4 Hz, 4H); 4.04
(“t”, 6.6 Hz, 2H)
0.88
(m, 9H)
0.88
(m, 9H)
b
L
1.86−1.20 (m, 48 H)
1.86−1.23 (m, 48 H)
(s, 2H)
7.37
(s, 2H)
[Ag(OTf)L]
phos-1
2.0
(br, 6H)
3.05
(m, 6H)
1.94, 1.65, 1.50, 1.26,
1.10 (m, 60 H)
7.63 (“d”, 8.8 Hz, 2H; 7.34
(“d”, 8.8 Hz, 2H)
7.71 (“d”, 8.8 Hz, 4H); 7.34
(“d”, 8.8 Hz, 4H)
7.71 (“d”, 8.8 Hz, 6H); 7.35
(“d”, 8.8 Hz, 6H)
7.38
2.45
(br, 6H)
3.24
(br, 6H)
3.95
(br, 6H)
3.00
0.88
(m, 9H)
0.88
(m, 18H)
0.88
(m, 27H)
phos-1.1
phos-1.2
phos-1.3
4.03 (m, 6H)
1.95−1.14 (m, 108H)
1.96−1.13 (m, 156H)
2.08−1.1 (m, 204H)
(s, 2H)
(m, 6H)
7.37
(s, 4H)
7.37
(s, 6H)
4.07 (“t”, 6.6 Hz, 4H); 4.04
(“t”, 6.6 Hz, 8H)
4.07 (“t”, 6.4 Hz, 6H); 4.04
(“t”, 6.4 Hz, 12H)
3.06
(br, 6H)
3.08
(br, 6H)
a
b
Data taken at RT in CDCl3, except for phos-1.1, whose data are in CD2Cl2. Values in ppm. L is the isocyanide ligand used in this work.
complexes. This downfield shift can be ascribed to deshielding
by the silver ion coordinated to the adjacent nitrogens, which
increases with the number of metals linked to adjacent
nitrogens. This shift has also been observed in other
metallophosphazenes in which silver atoms are coordinated
to the backbone nitrogen atoms.18b,c,20 The signal observed at
RT is a single peak even for phos-1.1 and phos-1.2, for which
an AB2 spin system corresponding to two types of phosphorus
atoms would be expected. This is attributable to a fluxional
process, which is typical in the coordination chemistry of silver
and can be attributed to exchange phenomena involving all the
phosphazene nitrogen atoms. Fluxionality can be quenched at
low temperature. Thus, the single broad peak observed for the
phosphazene phosphorus atoms in phos-1.1 and phos-1.2 at
RT is split into two signals at −80 °C (as shown in Figure 1 for
phos-1.1; see also Table 1). The signals for all compounds
(either at RT or low T) appear at similar positions to those
observed for the complexes [N3P3(NHCy)6{AgPPh3}n](TfO)n
(n = 2 or 3) mentioned before, which are also collected in
Table 1 for comparison.20
1
The H NMR spectra for complexes with phos-1 show the
signals due to the isocyanide ligands and the signals
corresponding to cyclohexylamino side units, which are all
shifted from those in the starting complexes. In the case of the
isocyanide ligands, the signals are only slightly shifted (see
Experimental Section and Table 2). These signals, specifically
those of NH and NH−CH, were verified by two-dimensional
1
heteronuclear H−13C HSQC correlations. Most significantly,
E
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1
2
the H NMR spectra of phos-1.1, phos-1.2 and phos-1.3 all
2P), JA−B = 30.1 Hz) (see Figure 3), which seems to indicate
that only one of the two stereoisomers, A or B, is present in
solution. For phos-2.1, two diastereomers A′ and B′ are also
expected (see Chart 5), namely, a pair of RP2,RP1- or SP2,SP1-
configured enantiomers (B′) and the diastereomer SP1,SP2,RP3-
(A′). At −60 °C, when the fluxional process is quenched, two
much more complicated signals are observed (the first is
centered at approximately δ = 22 (m, 2P) and the second at δ
= 19.30 (m, 1P)), which seems to indicate that both
stereoisomers A′ and B′ are present in solution. The spectra
of both compounds remains exactly the same at −80 °C. This
spectrum for phos-2.1 is shown in the Supporting Information.
The 1H NMR spectroscopic data of phos-2.1, phos-2.2, and
phos-2.3 are collected in Table 4. As observed for complexes
with phos-1, coordination at phosphazene leads to a
deshielding of the protons NH in all complexes. All these
data are also collected in the Experimental Section, as are the
13C{1H} NMR, the mass spectral and microanalytical data for
all new complexes. The assignation of the signals in the
13C{1H} NMR spectra was inferred using APT and 2D
correlation HSQC and HMBC 1H−13C spectra. The molecular
cation is only observed in the mass spectra for phos-2.1. For
the rest of compounds, peaks derived from the molecular
cations are observed. In general, peaks derived from the loss of
isocyanide ligands are observed.
show a unique type of cyclohexylamino units at RT, as a result
of the above-mentioned fluxional process. As can be observed
in Table 2, coordination at phosphazene leads in all complexes
to a deshielding of the protons NH, with a rise in the number
of metals coordinated to adjacent nitrogens, as was also
observed in the aforementioned similar silver phosphazenes,
[N3P3(NHCy)6{AgL}n](TfO)n (n = 2 or 3; L = PPh3 or
PPh2Me).20
The signals observed for complexes with mixed-substituent
trimer phos-2 in their 31P{1H} NMR spectra at RT also shift
downfield relative to the parent phosphazene (see Table 3)
Table 3. 31P{1H} NMR Spectroscopic Data for Silver
Complexes with phos-2
a
b
compound
δ[N−P−N] [2JP−P
20.96; 20.70 [44.3]
]
phos-2
phos-2.1
phos-2.2
phos-2.3
21.20 (br, 2P), 20.6 (br, 1P)
22.84 (br, 2P), 21.20 (br, 1P)
23.45 (“d”, 2P), 22.59 (“t”, 1P) [33.0]
a
Data recorded at RT in CDCl3 except for phos-2.2, whose data are
in CD2Cl2. Values in ppm. Values in Hz.
b
and appear at similar positions to those observed for complexes
nongem-trans-[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (n = 2
and 3; L = PPh3 or PPh2Me).20 In all compounds, even in
phos-2.3 (with three silver atoms), several signals are observed
because of the nongeminal-trans configuration of starting
phosphazene phos-2.24 Thus, the 31P{1H} NMR spectrum of
phos-2.3 at RT shows a single set of resonances of an AB2 spin
system, with peaks centered at δ = 23.45 (“d”, 2P) and 22.59
2.2. Thermal and Mesomorphic Properties. The
thermal and mesomorphic properties of silver complexes
were studied by differential scanning calorimetry (DSC) and
optical microscopy, and data are collected in Table 5. DSC
scans for all compounds are given in the Supporting
Information. It is well-known that the combination of adequate
metal−ligand and flexible chains in the design of metal-
lomesogens can provide complexes with a structure which is
difficult to approach, or simply unapproachable, for conven-
tional liquid crystals based on organic compounds. The
cyclotriphosphazene core introduces an additional complexity
to the design of liquid crystals, in particular when bulky groups
are linked to the P atoms of the phosphazene ring. As a metal−
ligand tecton to be linked to N atoms of this ring, the
precursor [Ag(OTf)L] (L = CNC6H4{OC(O)C6H2(3,4,5-
(OC10H21)3)}-4) was used. The polycatenar nature of this
ligand favors the appearance of mesomorphism in the
(“t”, 1P), JP−P = 33.0 Hz (see Figure 2, in which the 31P{1H}
NMR spectra at RT of phos-2.3 and its starting phosphazene,
phos-2, are collected).
For phos-2.1 and phos-2.2, the signals corresponding to the
phosphazene phosphorus are broad as a consequence of the
aforementioned fluxional process. For phos-2.2, two diaster-
eomers A and B are expected (see Chart 4), namely, a pair of
RP2,RP3- or SP2,SP3-configured enantiomers (B) and the
diastereomer RP1,RP2,SP3- (A).20 At −70 °C, when the fluxional
process is quenched, only a single set of resonances of an AB2
spin system is observed (at δ = 25.20 (“t”, 1P) and 20.41 (“d”,
2
Figure 2. 31P{1H} NMR spectra at RT of (a) phos-2 and (b) phos-2.3 in CDCl3.
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Chart 4. Diastereomers Expected for phos-2.2
Figure 3. 31P{1H} NMR spectra of phos-2.2 (a) at RT and (b) at −80 °C in CD2Cl2.
Chart 5. Diastereomers Expected for phos-2.1
precursor complex [Ag(OTf)L]. When this compound was
studied under the optical microscope, a mesophase was clearly
observed slightly above RT and exhibited clear evidence of
thermal decomposition together with isotropization of the
sample at around 145 °C. The first DSC scan of this
compound exhibited an endotherm corresponding to melting
transition at 33 °C but isotropization was not clearly observed
due to the thermal decomposition. Figure 4 displays the
mesophase texture of a sample of this precursor that was
directly heated to 145 °C to provoke isotropization and quickly
cooled below 100 °C to minimize decomposition. Under these
experimental conditions a focal conic texture with homeotropic
regions was observed, which can be assigned to a hexagonal
columnar mesophase (see below).
The complexation of the precursor to the cyclophosphazene
ring strongly modifies the geometry of the overall molecule.
The amino groups linked to the P atoms of the cyclic core
hinder the efficient arrangement of these polycatenar
compounds. Accordingly, the metallophosphazenes with one
or two silver atoms were amorphous materials except in the
case of phos-1.1. On the first heating DSC scan, this
compound exhibits an endotherm associated with melting
followed by decomposition. The related cyclotriphosphazene
with two silver units, phos-1.2, only exhibits a glass transition
at 16 °C before decomposition above approximately 60−70
°C. Similar cyclotriphosphazenes, phos-2.1 and phos-2.2, are
amorphous materials in both cases with Tg values of 15 and 18
°C, respectively. Furthermore, these compounds exhibited a
higher thermal stability, and no decomposition was observed
up to 100 °C. None of the cyclotriphosphazenes having either
one or two silver atoms exhibited mesomorphism.
The metallophosphazenes having three silver atoms, phos-
1.3 and phos-2.3, are highly viscous pastes at RT. In contrast
to the analogous cyclophosphazenes having one or two silver
atoms, these compounds exhibited birefringent textures under
the polarizing optical microscope as shown in Figure 5. In the
first heating scan, the exhibited textures are poorly defined;
however after shearing, a marbled-like texture was observed in
accordance with a mesomorphic behavior.
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When compound phos-1.3 was heated above 70 °C, a
progressive isotropization was detected, which seems to be
associated with a decomposition of the sample as the
subsequent cooling did not lead to the appearance of the
mesophase. In the first heating DSC scan of this compound
(previously cooled from RT to −20 °C), a glass transition was
detected at 16 °C followed by a broad endotherm at around 45
°C, immediately followed by the isotropization peak
(according to the microscope observation) the broadness of
which can be due to the progressive thermal decomposition.
The peak at around 45 °C might be due to the melting of some
residual crystalline regions (i.e., the compound is semicrystal-
line as obtained) since a mesophase−mesophase transition was
not observed by optical microscopy. Neither isotropic−
mesomorphic nor crystallization transitions were detected on
the cooling process, and only a glass transition at 13 °C was
detected on subsequent second heating. According to the
microscopy observations, this behavior can be due to thermal
decomposition when the sample was cooled down from the
isotropic phase at a relatively low cooling rate.
However, when phos-2.3 was studied by optical microscopy,
the isotropization was observed at a lower temperature range,
around 60 °C without evidence of thermal decomposition. In
this case, the subsequent cooling resulted in the appearance of
a grainy texture associated with a mesophase. When the sample
was annealed at around 55 °C for 1 h, close to the
isotropization temperature, a blurred Schlieren-type was
observed with homeotropic regions (Figure 6). If the sample
is progressively cooled below RT, then the sample vitrifies
maintaining this texture. This texture cannot be assigned
unambiguously to a calamitic or columnar mesophase. When
this compound was studied by DSC, the corresponding heating
and cooling curves were essentially similar on the different
scans. Thus, in the first scan a glass transition was observed at
15 °C. An endothermic peak was also observed at 61 °C
corresponding to the isotropization transition in accordance
with optical microscopy. On cooling, the isotropic−mesophase
transition was detected at 52 °C (minimum of the peak) as an
exothermic peak, with an enthalpic content similar to the
corresponding isotropization transition detected on heating
and followed by a vitrification process. The second heating
scan was similar to the first one as is collected in Table 5. No
decomposition was detected on the DSC scans even by heating
the sample up to 100 °C, which seems to confirm the higher
stability of series phos-2 of these silver(I) cyclophosphazene
complexes. Figure 7 exhibits the heating and cooling DSC
scans of this compound (a sample was heated up to 100 °C, far
from the isotropization transition, to check if decomposition
takes place).
2.3. Powder X-ray Diffraction Study of the Meso-
phases. The structures of the liquid crystal phases of
precursor [Ag(OTf)L] and derived mesomorphic compounds
phos-1.3 and phos-2.3 were investigated by powder X-ray
diffraction. X-ray diffractograms for all these compounds are
given in the Supporting Information. The study of [Ag(OTf)-
L] was performed at RT after heating up to 100 °C to get the
mesomorphic state. When cooling down to RT, the mesophase
was retained, and no crystalllization was observed. The X-ray
patterns recorded under these conditions were unambiguously
characteristic of a hexagonal columnar mesophase. A set of five
sharp spots were detected in the small-angle region with a
reciprocal spacing ratio 1: 3 : 2: 7 : 12 (see Table 5).
The five maxima correspond, respectively, to the (1 0), (1 1),
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Table 5. Thermal and Mesomorphic Properties and Structural Parameters of the Synthesized Metallocyclotriphosphazenes
and Silver(I) Precursor
a
b
compound
thermal transitions
structural parameters
c
[Ag(OTf)L]
phos-1.1
phos-1.2
phos-1.3
phos-2.1
phos-2.2
phos-2.3
1st h: K 33 (22.6) Colh 145 I (dec)
a = 42.2 (dobs = 36.5, 21.1, 18.0, 13.9, 10.7)
d
1st h: K 40 I
d
1st h: g 16 I
e
d
1st h: g 16 Colh 72 I
a = 50.7 (dobs = 44.0, 22.0, 12.6)
1st h/2nd h: g 15 I
1st h/2nd h: g 18 I
1st h: g 15 Colh 61 (3.6) I
2nd h: g 17 Colh 61 (3.2) I
a = 50.1 (dobs = 43.5, 21.7, 14.4)
a
Data corresponding to the first (1st h) and second heating DSC scans (2nd h); scan rate: 10 °C/min. K: crystalline phase; Colh: hexagonal
b
columnar mesophase; I: isotropic liquid phase. Temperature in °C. The phase transition enthalpy is given in parentheses (kJ/mol). a is the lattice
constant of the hexagonal columnar mesophase, in Å. dobs, in Å, are observed spacings. Decomposition of the sample is observed. The
isotropization temperature corresponds to the observation under the optical microscope. Decomposition is observed at temperatures above 60−
70 °C and the subsequent heating scans are not clearly reproducible due to decomposition. A broad endotherm is observed at 44 °C (see text).
c
d
e
Figure 6. Texture exhibited by a sample of phos-2.3 annealed at 55
°C on cooling for 1 h.
Figure 4. Mesomorphic texture exhibited by the precursor [Ag-
(OTf)L] at 80 °C.
these conditions, the mesophase is retained, and no
decomposition or crystallization phenomena are detected.
The patterns of compound phos-1.3 are very similar under
the two sets of conditions (before and after thermal treatment)
and consist of three reflections at low angles corresponding to
spacings of 44.0, 22.0, and 12.6 Å (see Table 5), and a broad
diffuse scattering maximum at high angles correspoding to a
mean distance of 4.5 Å. The three low-angle maxima are in the
(2 0), (2 1), and (2 2) reflections of the two-dimensional
hexagonal lattice and, from the measured spacings, a hexagonal
lattice constant a = 42.2 Å can be deduced. In addition, a
broad, diffuse scattering halo was detected at high angles,
characteristic of the liquidlike order of the aliphatic chains,
which confirms the mesomorphic nature of the phase.
For the study of complexes phos-1.3 and phos-2.3, several
X-ray patterns were recorded on samples of each compound at
RT above glass transition, both before and after thermal
treatment. The treatment consisted of fast heating of the
samples to the isotropic liquid and a fast cooling to RT. Under
reciprocal ratio 1: 2: 12, and this is consistent with a
hexagonal packing of columns. The three maxima correspond,
respectively, to the (1 0), (2 0), and (2 2) reflections of the
Figure 5. Texture exhibited by a sample of (a) phos-1.3 and (b) phos-2.3 at around 30 °C in the first heating. In the case of phos-2.3, the sample
was previously sheared.
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Figure 7. DSC second heating (top) and cooling (down) scans at 10 °C/min of phos-2.3 (the sample was heated up to 100 °C to check
decomposition). The baseline jump corresponds to glass transition, and the reversible mesophase-isotropic liquid transition is detected as
endothermic/exothermic peaks on the heating/cooling scans.
ρ = M × Z × 1024/(S × h × N )
two-dimensional hexagonal lattice, and from the measured
spacings, it is deduced that the hexagonal lattice constant a is
A
50.7 Å. From this value, the calculated spacing for the observed
reflections is 43.9, 22.0, and 12.7 Å, respectively, which is in
reasonable accordance with the experimentally measured
spacings. The diffuse character of the X-ray scattering observed
at high angles denotes both the conformational disorder of the
hydrocarbon chains in the isocyanide ligand and the absence of
a fixed stacking distance of the molecules along the column
axis.
where M is the molar mass in g, Z is the number of molecules
per unit cell, S is the cross-section area of the 2D hexagonal
lattice in Å2 (S = a2 × 3 /2, where a is the hexagonal lattice
constant), and NA is Avogadro’s number. Using the above-
mentioned formula, h can be expressed as a function of ρ and,
thus, it is deduced that h = 2.7 × Z/ρ for phos-1.3 and h = 2.6
× Z/ρ for phos-2.3. Considering that the density of these
compounds must be close to 1 g cm−3,25,26 reasonable values
for h are found when Z = 2. This means that two molecules of
phos-1.3 or phos-2.3 are necessary to fill the column cross-
section, and the estimated mean stacking distances h = 5.4 Å
for phos-1.3 and 5.2 Å for phos-2.3 are reasonable considering
the dimensions of these molecules. The driving force for
intermolecular association in pairs is probably related to the
peculiar geometry of these molecules that do not possess the
conventional features to yield columnar mesomorphism, in
particular a disk-shape. Indeed, in a starlike conformation the
void spaces between the three arms of the star render efficient
packing difficult. Moreover, the number of hydrocarbon chains
at the periphery of the isocyanide ligands are probably
insufficient to completely surround the rigid core in a single
molecule, which is a requirement for decorrelating the columns
and thus guarantees the mesomorphic nature of the columnar
packing. Therefore, two molecules must associate to efficiently
fill the column cross-section probably through some conforma-
tional change which allows each molecule to roughly adopt a
half-disk shape (Figure 8). This is possible by rotation of the
single bonds in the ester group of the peripheral ligand, as
described by Lehamnn for other star-shaped molecules.27 The
resulting aggregate has an approximate disk-shape and
possesses a total number of 18 hydrocarbon chains, which
Compound phos-2.3 yields X-ray diffraction images
qualitatively similar to those of phos-1.3. Analogous to
phos-1.3, the patterns recorded before and after thermal
treatment are practically identical: They contain a set of
reflections at low angles and a broad, diffuse band at high
angles corresponding to an average distance of 4.5 Å. The
three low-angle maxima reflections correspond to spacings
43.5, 21.7, and 14.4 Å (see Table 5). These spacings can be
indexed as the (1 0), (2 0), and (3 0) reflections of a two-
dimensional hexagonal lattice with a constant a of 50.1 Å.
From this value, the calculated spacing for the observed
reflections is 43.4, 21.7, and 14.5 Å, respectively, which is in
fair agreement with the experimentally measured spacings. The
diffuse character of the high-angle X-ray scattering is
characteristic of the intracolumnar disorder and is consistent
with the mesomorphic nature of the columnar array.
Although the absence of a fixed stacking distance in the
mesophases of these two compounds hinders the investigation
of certain structural details, some calculations can be carried
out to reach a rough view of the intracolumnar arrangement of
the molecules. The mean intermolecular distance h along the
column axis is related to the density ρ by the following
equation:25
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Figure 8. Folding of the starlike molecule allows adopting a half-disk-shaped conformation. Supramolecular association is driven by
nanosegregration of chemically different regions and efficient space-filling. Two complementary molecules generate an overall disk shape, which
promotes columnar mesomorphism.
are enough to spread out and occupy all the available space
between neighboring columns. Moreover, segregation of
dissimilar building blocks into different regions is achieved,
and in this way, the requirements to generate columnar
mesomorphism are fulfilled. Notably, there is no evidence that
the columns are generated by staking of discrete dimers.
Instead, there must be a supramolecular assembling of
molecules with short-range alternating orientation but with
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solution (5 × 10−4 M) with a Philips PW 9509 apparatus. DSC was
performed using a DSC Q2000 from TA Instruments with samples
(2−5 mg) sealed in aluminum pans and a scanning rate of 10 °C/min
under a nitrogen atmosphere. In general, the peaks obtained were
broad and the transition temperatures were therefore read at the
maximum of the peaks. Glass transitions were read at midpoint of the
baseline jump. The X-ray diffraction patterns were obtained with a
pinhole camera (Anton−Paar) operating with a point-focused Ni-
filtered Cu Kα beam. The samples were held in Lindemann glass
capillary tubes (0.9 mm diameter) and heated, when necessary, with a
variable-temperature oven. The patterns were collected on flat
photographic films. The capillary axis and the film were perpendicular
to the X-ray beam. Spacings were obtained using Bragg’s law.
Hexachlorocyclotriphosphazene, [N3P3Cl6] (Stream Chemicals),
was purified by recrystallization from hot hexane and dried in vacuum.
The starting cyclotriphosphazenes, [N3P3(NHCy)6] and nongeminal-
trans-[N3P3(NHCy)3(NMe2)3], were prepared by a literature
method.20 The pro-mesogenic isocyanide was also prepared by
literature method,4b,21a starting from acid chlorides ClC(O)-
C6H2(3,4,5-(OC10H21)3,29 which were also prepared in turn by a
literature method (see the Supporting Information). Characterization
data of the pro-mesogenic isocyanide are included in the text for
comparison.
long-range random orientation. The absence of an X-ray
reflection corresponding to the repeating distance along the
columnar axis supports a disordered arrangement of molecules.
Due to the nonsymmetrical structure of phos-2.3, association
in this complex can take place in different mutual orientations.
However, as the liquid crystal state is fluid and dynamic, this
phenomenon does not modify the shape and size of the
resulting “disk”. Nevertheless, this additional degree of
disorder might contribute to the differences observed in the
mesomorphic properties, in particular the lower mesophase-to-
isotropic liquid transition temperature of phos-2.3 compared
to that of phos-1.3.
Applying the above-mentioned estimation to the precursor
[Ag(OTf)L], it is concluded that for a density close to 1 g
cm−3 five molecules are needed to fill a column section of
length of about 5.1 Å. The columnar structure probably
consists of a central rigid core that contains the silver atoms
and the triflate anions, as well as a peripheral region
accommodating the conformationally disordered aliphatic
chains. This model is consistent with the structures found
for the columnar mesophases of similar polycatenar com-
pounds.28
4.2. Synthesis and Spectroscopic Characterization Data.
4.2.1. Synthesis of [Ag(OTf)L] (L = CNC6H4{OC(O)C6H2(3,4,5-
(OC10H21)3)}-4). To a solution of Ag(TfO) (0.051 g, 0.2 mmol) in
dry acetone (20 mL) was added isocyanide L (L = CNC6H4{OC-
(O)C6H2(3,4,5-(OC10H21)3)}-4) (0.138 g, 0.2 mmol), and the
mixture was stirred for 10 min protected from light and filtered off.
Evaporation of the solvent gave the product as a white solid, which
was dried in vacuo at RT for 24 h. Yield: 0.171 g (90%).
3. CONCLUSIONS
The ring nitrogen atoms in the (amino)cyclotriphosphazenes
[N3 P3 (NHCy)6 ] (phos-1) and nongem-trans-
[N3P3(NHCy)3(NMe2)3] (phos-2) have shown to have
sufficient basicity to coordinate to the silver(I) fragment
containing a pro-mesogenic ligand, “AgL” (L = CNC6H4{OC-
(O)C6H2(3,4,5-(OC10H21)3)}-4). Thus, the reaction of phos-
1 or phos-2 with the silver complex [Ag(OTf)L] (L =
CNC6H4{OC(O)C6H2(3,4,5-(OC10H21)3)}-4; OTf =
OSO2CF3), in different molar ratios, 1:1, 1:2, or 1:3, led to a
series of two of cationic metallophosphazenes,
[N3P3(NHCy)6{AgL}n](TfO)n (phos-1.n) and nongem-trans-
[N3P3(NHCy)3(NMe2)3{AgL}n](TfO)n (phos-2.n) with n =
1, 2, or 3. According to the spectroscopic data, in all
metallophosphazenes obtained, the silver fragments “AgL”
are coordinated to nitrogen atoms of the phosphazene ring and
the number of silver fragments (n) depends on the molar ratio
used on the complexation. Metallocyclophosphazenes having
one or two silver fragments were not liquid crystalline
materials. However, phos-1.3 and phos-2.3, having three
silver units, were liquid crystals at RT according to the optical
microscopy studies. X-ray diffraction data were in accordance
with a hexagonal columnar mesophase. A model consisting of
the supramolecular stacking of molecules with complementary
shapes associated in pairs has been proposed to explain the
columnar mesomorphism and structural parameters. The
starting silver complex, [Ag(OTf)L], also exhibited a columnar
hexagonal mesophase at RT.
Anal. Calcd (%) for C45H69AgF3NO8S (948.96): C 56.96, H 7.33,
N 1.48, S 3.38. Found: C 57.07, H 7.56, N 1.67, S 3.52. IR (ATR):
2197 (s) cm−1 (CN); 1733 (s) cm−1 (CO); other bands: 1283
(m, br), 1246 (s, sh), 1222 (s), 1195 (vs), 1178 (vs), 1116 (s), 1098
(m, sh), 1027 (s) cm−1. 1H NMR ((CD3)2CO): δ = 7.93 (“d”, 3JH−H
3
= 8.8 Hz, 2H; CNC6H4O), 7.56 (“d”, JH−H = 8.8 Hz, 2H;
3
CNC6H4O), 7.45 (s, 2H; C6H2(OC10H21-p)3), 4.10 (“t”, JH−H = 6.4
3
Hz, 4H; OCH2), 4.09 (“t”, JH−H = 6.8 Hz, 2H; OCH2), 1.87−1.28
1
(m, 48H; CH2), 0.88 (m, 9H; CH3). H NMR (CDCl3): δ = 7.63
3
(“d”, JH−H = 8.9 Hz, 2H; CNC6H4O), 7.37 (s, 2H; C6H2(OC10H21-
3
3
p)3), 7.36 (“d”, JH−H = 8.9 Hz, 2H; CNC6H4O), 4.07 (“t”, JH−H
=
3
6.4 Hz, 4H; OCH2), 4.04 (“t”, JH−H = 6.6 Hz, 2H; OCH2), 1.86−
1.23 (m, 48H; CH2), 0.88 (m, 9H; CH3). 19F NMR (CDCl3): δ =
−77.59. 13C{1H} APT NMR (CDCl3, RT) δ = CN not detected,
164.35 (1C; C6, C(O)O); 153.30 (1C; C5 or C2), 153.23 (2C; C9),
143.76 (1C; C10), 128.67 (2C; C3), 123.87 (2C; C4), 122.83 (1C;
1
C7), 122.32 (1C; C2 or C5), 108.86 (2C; C8); 120.58 (q, JC−F
=
320.8 Hz, 1C; SO3CF3); 73.81 (1C; OCH2), 69.50 (2C;OCH2),
32.09, 32.06, 30.49, 29.88, 29.82, 29.77, 29.73, 29.70, 29.54, 29.49,
29.43, 26.23, 26.19, 22.85, 22.83(24C; CH2).14.26 (3C; CH3). MS
(MALDI+, DCTB): m/z (%) = 988 (30) [M + K]+, 801 (100) [M −
OTf + H]+, 1492 (40) [AgL2]+.
Numering of the C atoms of the isocyanide ligand in all complexes:
4. EXPERIMENTAL SECTION
4.1. General Data. Infrared spectra were recorded in the range of
4000−250 cm−1 on a PerkinElmer Spectrum-100 (ATR mode) FT-IR
spectrometer. Carbon, hydrogen, nitrogen, and sulfur analyses were
performed using a PerkinElmer 240 B microanalyser. NMR spectra
were recorded on a Bruker AV 400 spectrometer. Chemical shifts are
4.2.2. Synthesis of [N3P3(NHCy)6{AgL}n](TfO)n (phos-1.n, n = 1, 2,
or 3). To a solution of [Ag(OTf)L] (0.095 g, 0.1 mmol for phos-1.1;
0.19 g, 0.2 mmol for phos-1.2; 0.285 g, 0.3 mmol for phos-1.3) in dry
dichloromethane (15 mL) was added [N3P3(NHCy)6] (72.4 mg, 0.1
mmol), and the mixture was stirred for 30 min protected from light
and filtered off. The solvent was evaporated and the resulting
compounds were dried in vacuo at RT for 24 h.
phos-1.1 (134 mg, yield: 80%). Elemental analysis calcd (%) for
C81H141AgF3N10O8P3S (1672.9): C 58.16, H 8.50, N 8.37, S 1.92.
Found: C 58.04, H 8.70, N 8.15, S 2.03. IR (ATR): 3313 cm−1 (w,
1
quoted relative to SiMe4 (TMS, H and 13C, external) and H3PO4
(85%) (31P, external) and given in parts per million (ppm). MALDI-
TOF mass spectrometry was carried out on a Micromass Autospec
instrument using dithranol or DCTB (trans-2-[3-(4-tert-butylphenyl)-
2-methyl-2-propenylidene]malononitrile) as matrix. Conductivity for
compounds phos-1.1 and phos-1.2 was measured in dichloromethane
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br) (N−H); 2172 cm−1 (m) (CN); 1735 cm−1 (s) (CO); other
bands: 1289 (m), 1232 (s), 1220 (s), 1197 (vs), 1180(s), 1118 (s),
1098 (vs), 1029 (s) cm−1. 31P{1H} NMR (CDCl3, RT): δ = 15.60 (s,
br; N3P3 ring). 31P{1H} NMR (CD2Cl2, RT): δ = 15.19 (s, br; N3P3
ring). 31P{1H} NMR (CD2Cl2, −80 °C): δ = 15.98 (“d”, 2P), 14.09
(“t”, 1P) (AB2 system, 2JP−P= 48.2 Hz; N3P3 ring). 1H NMR (CD2Cl2,
4.2.3. Synthesis of nongem-trans-[N3P3(NHCy)3(NMe2)3{AgLn}]-
(TfO)n (phos-2.n, n = 1, 2, or 3). To a solution of [Ag(OTf)L]
(0.095 g, 0.1 mmol for phos-2.1; 0.19 g, 0.2 mmol for phos-2.2;
0.285 g, 0.3 mmol for phos-2.3) in dry dichloromethane (15 mL) was
added nongem-trans-[N3P3(NHCy)3(NMe2)3] (phos-2) (0.056 g, 0.1
mmol), and the mixture was stirred for 30 min protected from light
and filtered off. The solvent was evaporated and the resulting
compounds were dried in vacuo at RT for 24 h.
3
RT): δ = 7.63 (“d”, JH−H = 8.8 Hz, 2H; CNC6H4O), 7.38 (s, 2H;
C6H2(OC10H21-p)3), 7.34 (“d”, 3JH−H = 8.8 Hz, 2H; CNC6H4O), 4.03
(m, 6H; OCH2), 3.0 (br, 6H, NH−CH), 2.45 (br, 6H; NH), 1.95−
1.14 (m, 108H; CH2), 0.88 (m, 9H; CH3). 19F NMR (CDCl3, RT): δ
= −77.79. 13C{1H} APT NMR (CDCl3, RT) δ = CN not detected,
164.42 (1C; C6, C(O)O); 153.18 (2C; C9), 152.73 (1C; C5 or C2),
phos-2.1 (117 mg, yield: 77.5%). Elemental analysis calcd (%) for
C69H123AgF3N10O8P3S (1510.63): C 54.86, H 8.21, N 9.27, S 2.12.
Found: C 54.60, H 8.44, N 9.01, S 2.10. IR (ATR): 3314 cm−1 (w,
br) (N−H); 2182 cm−1 (m) (CN); 1736 cm−1 (s) (CO); other
bands: 1279 (m), 1247 (s), 1218 (s), 1194 (vs), 1177(vs), 1114 (s),
1100 (s), 1028 (s) cm−1. 31P{1H} NMR (CDCl3, RT): 21.20 (br, 2P),
20.60 (br, 1P). 31P{1H} NMR (CDCl3, −60 °C): 22.00 (m, 2P),
19.30 (m, 1P). 31P{1H} NMR (CD2Cl2, RT): 20.94 (vbr). 31P{1H}
143.65 (1C; C10), 128.58 (2C; C3), 123.58 (2C; C4), 122.97 (1C;
1
C7), 122.56 (1C; C2 or C5), 108.81 (2C; C8); 120.76 (q, JC−F
=
320.3 Hz, 1C; SO3CF3), 73.76 (1C; OCH2); 69.46 (2C;OCH2);
50.51(6C, NH−CH), 36.34 (12C; CH2, NHC6H11), 32.06, 32.03,
30.47, 29.85, 29.79, 29.75, 29.70, 29.68, 29.51, 29.47, 29.41, 26.20,
26.17, 25.57, 25.42, 22.80 (42C; CH2), 14.23 (3C; CH3). MS
(MALDI+, DCTB): m/z (%) = 1555.7 (90) [{N3P3(NHCy)6}2Ag]+,
830.2 (100) [N3P3(NHCy)6Ag]+.
1
NMR (CD2Cl2, −80 °C): 21.93 (m, 2P), 19.41 (m, 1P). H NMR
3
(CDCl3, RT): δ = 7.65 (“d”, JH−H = 8.8 Hz, 2H; CNC6H4O), 7.36
3
(s, 2H; C6H2(OC10H21-p)3), 7.30 (“d”, JH−H = 8.8 Hz, 2H;
3
CNC6H4O), 4.06 (“t”, JH−H = 6.4 Hz, 2H; OCH2), 4.03 (“t”,
3JH−H = 6.4 Hz, 4H; OCH2), 2.98 (br, 3H, NH−CH), 2.67 (m, N =
12 Hz, 12H, NMe2), 2.65 (m, N = 12.4 Hz, 6H, NMe2), 2.00 (br, 3H;
NH), 1.98−1.20 (m, 78H; CH2), 0.87 (m, 9H; CH3). 19F NMR
(CDCl3, RT): δ = −77.88. 13C{1H} APT NMR (CDCl3, RT) δ = CN
not detected, 164.42 (1C; C6, C(O)O), 153.21 (2C; C9), 152.87 (1C;
C5 or C2), 143.67 (1C; C10), 128.71 (2C; C3), 123.61 (2C; C4),
123.01 (1C; C7), 122.36 (1C; C2 or C5), 108.86 (2C; C8); 120.63 (q,
1JC−F = 320.3 Hz, 1C; SO3CF3), 73.79 (1C; OCH2); 69.50
(2C;OCH2); 50.54 (2C; NH−CH), 50.24 (1C; NH−CH), 37.50,
37.35 (6C; NMe2), 36.17, 35.83 (6C; CH2, NHC6H11), 32.09, 32.05,
30.49, 29.87, 29.81, 29.77, 29.72, 29.70, 29.53, 29.49, 29.44, 26.22,
26.19, 25.70, 25.63, 25.56, 25.48, 22.83 (33C; CH2).14.25 (3C; CH3).
MS (MALDI+, DCTB): m/z (%) = 1361.9 (30) [M − TfO]+,
1231.6(100) [{N3P3(NHCy)3(NMe2)3}2Ag]+.
phos-1.2 (223 mg, yield: 85%). Elemental analysis calcd (%) for
C126H210Ag2F6N11O16P3S2 (2621.86): C 57.72, H 8.07, N 5.88, S
2.45. Found: C 57.95, H 8.37, N 5.90, S 2.38. IR (ATR): 3305 cm−1
(m, br) (N−H); 2180 cm−1 (m) (CN); 1736 cm−1 (s) (CO);
other bands: 1280 (s), 1230 (s), 1220 (vs), 1195 (s), 1180 (vs), 1162
(s, sh), 1115(s), 1103 (s), 1029 (s) cm−1. 31P{1H} NMR (CDCl3,
RT): δ = 16.71 (s, br; N3P3 ring). 31P{1H} NMR (CD2Cl2, RT): δ =
16.30 (s, br; N3P3 ring). 31P{1H} NMR (CD2Cl2, −80 °C): δ = 17.18
(“t”, 1P), 13.58 (“d”, 2P) (AB2 system, 2JP−P= 35.6 Hz; N3P3 ring). 1H
NMR (CDCl3, RT): δ = 7.71 (“d”, 3JH−H = 8.8 Hz, 4H; CNC6H4O),
3
7.37 (s, 4H; C6H2(OC10H21-p)3), 7.34 (“d”, JH−H = 8.8 Hz, 4H;
CNC6H4O), 4.07 (“t”, 3JH−H = 6.6 Hz, 4H; OCH2), 4.04 (“t”, 3JH−H
=
6.6 Hz, 8H; OCH2), 3.24 (br, 6H, NH−CH), 3.06 (br, 6H, NH),
1.96−1.13 (m, 156H; CH2), 0.88 (m, 18H; CH3). 19F NMR (CDCl3,
RT): δ = −77.72 (s). 13C{1H} APT NMR (CDCl3, RT) δ = CN not
detected, 164.41 (2C; C6, C(O)O), 153.19 (4C; C9), 152.83 (2C; C5
or C2), 143.64 (2C; C10), 128.60 (4C; C3), 123.66 (4C; C4), 122.94
phos-2.2 (202 mg, yield: 82%). Elemental analysis calcd (%) for
C114H192Ag2F6N11O16P3S2 (2459.59): C 55.67, H 7.87, N 6.26, S
2.61. Found: C 56.01, H 8.21, N 6.40, S 2.41. IR (ATR): 3300 cm−1
(m, br) (N−H); 2185 cm−1 (m) (CN); 1737 cm−1 (s) (CO);
other bands: 1282 (s), 1230 (s), 1221 (vs), 1195 (s), 1178 (vs), 1162
(s), 1114(s), 1091 (s), 1029 (s) cm−1. 31P{1H} NMR (CD2Cl2, RT):
δ = 22.84 (br, 2P), 21.20 (br, 1P). 31P{1H} NMR (CD2Cl2, −80 °C):
δ = 25.20 (“t”, 1P), 20.41 (“d”, 2P) (AB2 system, 2JA−B = 30.1 Hz). 1H
NMR (CD2Cl2, RT): δ = 7.71 (“d”, 3JH−H = 8.9 Hz, 4H; CNC6H4O),
(2C; C7), 122.37 (2C; C2 or C5), 108.79 (4C; C8); 120.78 (q, 1JC−F
=
321.3 Hz, 2C; SO3CF3), 73.78 (2C; OCH2); 69.45 (4C;OCH2);
50.69 (6C, NH−CH), 36.41 (12C; CH2, NHC6H11), 32.08, 32.05,
30.48, 29.87, 29.81, 29.77, 29.72, 29.53, 29.49, 29.42, 26.22, 26.18,
25.54, 25.50, 22.83 (66C; CH2).14.26 (6C; CH3). MS (MALDI+,
DIT): m/z (%) = 1780.3 (2) [M − L − TfO]+, 1492.2 (2) [AgL2]+,
949.1(2) [Ag(TfO)L]+, 831.7(2) [N3P3(NHCy)6Ag]+, 800.7 (4)
[AgL]+, 724.7(100) [N3P3(NHCy)6]+.
3
7.38 (s, 4H; C6H2(OC10H21-p)3), 7.38 (“d”, JH−H = 8.9 Hz, 4H;
CNC6H4O), 4.05 (“t”, 3JH−H = 6.4 Hz, 4H; OCH2), 4.04 (“t”, 3JH−H
=
6.4 Hz, 8H; OCH2), 3.78 (br, 3H; NH), 2.99 (br, 3H; NH−CH),
2.77 (m, N= 14.4 Hz, 18H; NMe2), 2.05−1.20 (m, 126H; CH2), 0.88
(m, 18H; CH3). 19F NMR (CD2Cl2, RT): δ = −77.88. 13C{1H} APT
NMR (CDCl3, RT) δ = CN not detected, 164.42 (2C; C6, C(O)O),
153.19 (4C; C9), 152.81 (2C; C5 or C2), 143.63 (2C; C10), 128.68
(4C; C3), 123.62 (4C; C4), 122.95 (2C; C7), 122.45 (2C; C2 or C5),
phos-1.3 (339 mg, yield: 95%). Elemental analysis calcd (%) for
C171H279Ag3F9N12O24P3S3 (3570.82): C 57.52, H 7.86, N 4.71, S
2.69. Found: C 57.30, H 7.51, N 4.53, S 2.60. IR (ATR): 3314 cm−1
(m, br) (N−H); 2204 cm−1 (m) (CN); 1737 cm−1 (s) (CO);
other bands: 1283 (m), 1234 (s), 1222 (vs), 1190 (s), 1176 (vs),
1162 (vs), 1112 (vs), 1091 (vs, br), 1026 (vs) cm−1. 31P{1H} NMR
(CDCl3, RT): δ = 18.97 (s; N3P3 ring). 31P{1H} NMR (CD2Cl2, RT):
δ = 18.44 (s, br; N3P3 ring). 31P{1H} NMR (CD2Cl2, −80 °C): δ =
1
108.79 (4C; C8); 120.77 (q, JC−F = 322.3 Hz, 2C; SO3CF3), 73.78
(2C; OCH2); 69.46 (4C;OCH2); 50.64 (2C; NH−CH), 50.32 (1C;
NH−CH), 37.50 (4C; NMe2), 37.35 (2C; NMe2), 36.18, 36.10, 35.77
(6C; CH2, NHC6H11), 32.08, 32.05, 30.49, 29.87, 29.81, 29.77, 29.73,
29.70, 29.53, 29.49, 29.42, 26.22, 26.19, 25.66, 25.59, 25.50, 22.85,
22.83 (57C; CH2).14.26 (6C; CH3). MS (MALDI+, DIT): m/z (%) =
1492.2 (1) [AgL2 ]+ , 800.7 (1) [AgL]+ , 669.6(2)
[N3P3(NHCy)3(NMe2)3Ag]+, 562.5(100) [N3P3(NHCy)3(NMe2)3
+ H]+.
1
3
18.35 (s; N3P3 ring). H NMR (CDCl3, RT): δ = 7.71 (“d”, JH−H
=
8.8 Hz, 6H; CNC6H4O), 7.37 (s, 6H; C6H2(OC10H21-p)3), 7.35 (“d”,
3
3JH−H = 8.8 Hz, 6H; CNC6H4O), 4.07 (“t”, JH−H = 6.4 Hz, 6H;
OCH2), 4.04 (“t”, 3JH−H = 6.4 Hz, 12H; OCH2), 3.95 (br, 6H, NH−
CH), 3.08 (br, 6H, NH), 2.08−1.10 (m, 204H; CH2), 0.88 (m, 27H;
CH3). 19F NMR (CDCl3, RT): δ = −77.69 (s). 13C{1H} APT NMR
(CDCl3, RT) δ = CN not detected, 164.40 (3C; C6, C(O)O); 153.31
(6C; C9), 152.90 (3C; C5 or C2), 143.63 (3C; C10), 128.93 (6C; C3),
123.86 (6C; C4), 122.83 (3C; C7), 108.89 (6C; C8); 120.05 (q, 1JC−F
= 321.4 Hz, 3C; SO3CF3), 73.74 (3C; OCH2); 69.47 (6C;OCH2);
51.47 (6C, NH−CH), 36.54, (12C; CH2, NHC6H11), 32.08, 32.05,
30.49, 29.87, 29.81, 29.77, 29.73, 29.53, 29.49, 29.42, 26.22, 26.18,
25.52, 25.2, 22.83 (90C; CH2).14.26 (9C; CH3). MS (MALDI+,
DIT): m/z (%) = 1492.2 (1) [AgL2]+, 949.1(1) [Ag(TfO)L]+,
832.7(1) [N3P3(NHCy)6Ag + H]+, 800.7 (1) [AgL]+, 724.7(100)
[N3P3(NHCy)6]+.
phos-2.3 (290 mg, yield: 85%). Elemental analysis calcd (%) for
C159H261Ag3F9N12O24P3S3 (3408.55): C 56.03, H 7.72, N 4.93, S
2.82. Found: C 55.95, H 7.61, N 4.51, S 2.60. IR (ATR): 3292 cm−1
(m, br) (N−H); 2204 cm−1 (m) (CN); 1737 cm−1 (s) (CO);
other bands: 1283 (m), 1237 (s), 1221 (vs), 1187 (s), 1178 (vs),
1162 (vs), 1114 (vs), 1092 (vs, br), 1027 (vs) cm−1. 31P{1H} NMR
(CDCl3, RT): δ = 23.45 (“d”, 2P), 22.59 (“t”, 1P) (AB2 system,
1
3
2JA−B= 33.0 Hz). H NMR (CDCl3, RT): δ = 7.69 (“d”, JH−H = 8.8
Hz, 6H; CNC6H4O), 7.37 (s, 6H; C6H2(OC10H21-p)3), 7.35 (“d”,
3JH−H = 8.8 Hz, 6H; CNC6H4O), 4.41 (br, 1H, NH), 4.29 (br, 2H,
M
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Inorg. Chem. XXXX, XXX, XXX−XXX

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Article
3
3
NH), 4.07 (“t”, JH−H = 6.4 Hz, 6H; OCH2), 4.04 (“t”, JH−H = 6.4
Hz, 12H; OCH2), 3.05 (br, 3H, NH−CH), 2.84 (m, N= 11.2 Hz,
18H; NMe2), 2.06−1.20 (m, 174H; CH2), 0.88 (m, 27H; CH3). 19F
NMR (CDCl3, RT): δ = −77.72. 13C{1H} APT NMR (CDCl3, RT) δ
= CN not detected, 164.34 (3C; C(O)O); 153.29 (3C; C5 or C2),
153.21 (6C; C9), 143.75 (3C; C10), 128.80 (6C; C3), 123.80 (6C;
C4), 122.85 (3C; C7), 122.21 (3C; C2 or C5), 108.86 (6C; C8);
120.62 (q, 1JC−F = 320.0 Hz, 3C; SO3CF3), 73.80 (3C; OCH2); 69.44
(4C;OCH2); 51.82 (3C; NH−CH), 37.75 (6C; NMe2), 36.41, 35.82
(6C; CH2, NHC6H11), 32.08, 30.49, 29.87, 29.81, 29.77, 29.72, 29.70,
29.53, 29.49, 29.43, 26.23, 26.19, 25.61, 25.54, 25.26, 22.85, 22.83
(81C; CH2).14.25 (6C; CH3). MS (MALDI+, DCTB): m/z (%) =
1491.8 (100) [AgL2]+, 1361.7 (20) [N3P3(NHCy)3(NMe2)3AgL]+,
1231.5 (10) [{N3P3(NHCy)3(NMe2)3}2Ag]+, 800.3 (65) [AgL]+.
ACKNOWLEDGMENTS
■
This work was funded by the Ministerio de Economia y
Competitividad (MINECO)-FEDER, under the project grant
number MAT2017-84838P, and Gobierno de Aragon-FEDER
(Liquid Crystals and Polymers Group E47_17R, FEDER
́
2014-2020 “Construyendo Europa desde Aragon”).
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ASSOCIATED CONTENT
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c00124.
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AUTHOR INFORMATION
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̃
Corresponding Author
́
́
́
Josefina Jimenez − Departamento de Quımica Inorganica,
́
́
́
Facultad de Ciencias - Instituto de Sıntesis Quımica y Catalisis
́
Homogenea (ISQCH), Universidad de Zaragoza-CSIC,
Zaragoza 50009, Spain; orcid.org/0000-0002-3444-0851;
Email: jjimvil@unizar.es
Authors
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Nguyen, T.-Q.; Evans, H.; Resendiz, M. J.; Baruah, T.; Metta, A.; Arif,
A.; Noveron, J. C. Mesomorphic Behavior in Silver(I) N-(4-Pyridyl)
Benzamide with Aromatic π−π Stacking Counterions. Materials 2018,
11, 1666.
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with Molecular Weight Control. J. Am. Chem. Soc. 1995, 117, 7035−
7036. For a number of references, see also (c) Allcock, H. R. The
expanding field of polyphosphazene high polymers. Dalton Trans.
2016, 45, 1856−1862.
́
́
́
Jose Antonio Sanz − Departamento de Quımica Inorganica,
́
́
́
Facultad de Ciencias - Instituto de Sıntesis Quımica y Catalisis
́
Homogenea (ISQCH), Universidad de Zaragoza-CSIC,
Zaragoza 50009, Spain
Jose Luis Serrano − Departamento de Quımica Organica,
Facultad de Ciencias - Instituto Universitario de Nanociencia de
Aragon (INA), Universidad de Zaragoza, Zaragoza 50018,
Spain; Departamento de Quımica Organica, Facultad de
Ciencias - Instituto de Ciencia de Materiales de Aragon
(ICMA), Universidad de Zaragoza-CSIC, Zaragoza 50009,
Spain; orcid.org/0000-0001-9866-6633
Joaquín Barbera − Departamento de Quımica Organica,
Facultad de Ciencias - Instituto de Ciencia de Materiales de
Aragon (ICMA), Universidad de Zaragoza-CSIC, Zaragoza
50009, Spain; orcid.org/0000-0001-5816-7960
Luis Oriol − Departamento de Quımica Organica, Facultad de
Ciencias - Instituto de Ciencia de Materiales de Aragon
́
́
́
́
́
́
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Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c00124
Notes
The authors declare no competing financial interest.
N
https://dx.doi.org/10.1021/acs.inorgchem.0c00124
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