Reactivity of NO2 with Porous and Conductive Copper Azobispyridine Metallopolymers

Article abstract of DOI:10.1021/acs.inorgchem.9b01190

We report the reactivity of copper azobispyridine (abpy) metallopolymers with nitrogen dioxide (NO₂). The porous and conductive [Cu(abpy)]_n mixed-valence metallopolymers undergo a redox reaction with NO₂, resulting in the disproportionation of NO₂ gas. Solid- and gas-phase vibrational spectroscopy and X-ray analysis of the reaction products of the NO₂-dosed metallopolymer show evidence of nitrate ions and nitric oxide gas. Exposure to NO₂ results in complete loss of porosity and a decrease in the room-temperature conductivity of the metallopolymer by four orders of magnitude with the loss of mixed-valence character. Notably, the porous and conductive [Cu(abpy)]_n metallopolymers can be reformed by reducing the Cu-nitrate species.

Full text of DOI:10.1021/acs.inorgchem.9b01190

Article
Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
Reactivity of NO with Porous and Conductive Copper
2
Azobispyridine Metallopolymers
†
,⊥
†,⊥
†,§
Shengkai Wang,‡
Naomi E. Clayman,
Mary Anne Manumpil, Benjamin D. Matson,
†
,§
,†
,†
Adam H. Slavney, Ritimuka Sarangi,* Hemamala I. Karunadasa,* and Robert M. Waymouth*
†
Department of Chemistry, Stanford University, Stanford, California 94305, United States
‡
Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States
§
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
S Supporting Information
*
ABSTRACT: We report the reactivity of copper azobispyr-
idine (abpy) metallopolymers with nitrogen dioxide (NO2).
The porous and conductive [Cu(abpy)]n mixed-valence
metallopolymers undergo a redox reaction with NO , resulting
2
in the disproportionation of NO gas. Solid- and gas-phase
2
vibrational spectroscopy and X-ray analysis of the reaction
products of the NO -dosed metallopolymer show evidence of
2
nitrate ions and nitric oxide gas. Exposure to NO results in
2
complete loss of porosity and a decrease in the room-
temperature conductivity of the metallopolymer by four
orders of magnitude with the loss of mixed-valence character.
Notably, the porous and conductive [Cu(abpy)]n metal-
lopolymers can be reformed by reducing the Cu-nitrate species.
INTRODUCTION
material, we anticipated that the neutral metallopolymer might
react with oxidizing gases such as NO2.
■
Combustion of fossil fuels that powers much of the
transportation and industry in today’s society results in the
release of toxic gases into the atmosphere. Among these gases
Herein, we report the reaction of the porous and conductive
[
Cu(abpy)] with NO gas (Scheme 1). This gas/solid redox
n 2
is NO , a dangerous brown gas found in smog. Continued
2
Scheme 1. Proposed Reaction of [Cu(abpy)] with NO Gas
n
2
exposure to low concentrations (∼1 ppm) of NO can result in
2
chronic respiratory problems; short-term exposure to 10 ppm
induces acute respiratory difficulties, and concentrations
1
nearing 100 ppm can result in death. These biological and
environmental concerns have motivated studies to identify
1
−5
materials that can sense or react with and capture NO2.
Sensor technologies have been developed to detect small
1
−5
amounts of NO gas. Materials that react with NO without
2
2
interfering reactions with more abundant gaseous species (N2,
O , CO ) also have potential environmental applications for
2
2
the capture and sequestration of these toxic gases.
6
We previously described the electrically conductive and
porous copper azobispyridine (abpy) metallopolymers [Cu-
(
abpy)] . These metallopolymers exhibit an unusual combina-
n
reaction results in oxidation of the metallopolymer and the
−
1
tion of substantial conductivity (0.18 S·cm
temperature) and porosity (90 m ·g ). The conductivity of
at room
reductive disproportionation of NO gas into nitric oxide
2
2
−1
−
(NO) gas and nitrate anions (NO ). Notably, after exposure
3
the neutral polymer, with oxidation states formally assigned as
to NO gas, the resulting oxidized material can be reduced to
2
+
−•
6
[
Cu (abpy )] , was attributed to its mixed-valence character.
regenerate [Cu(abpy)] with approximately 75% recovery of
n
n
The [Cu(abpy)] metallopolymer can be reversibly oxidized at
the porosity and conductivity of the original metallopolymer.
n
−
10
−1
−
0.8 V vs Ag/AgNO to the insulating (<10 S·cm ) and
3
nonporous cationic metallopolymer, formally assigned as
Received: April 23, 2019
+
0
[Cu (abpy )X] (X = monoanion). As a reducing, porous
n
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.9b01190
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
RESULTS AND DISCUSSION
■
Metallopolymer [Cu(abpy)] , generated from the chemical
n
6
reduction of [Cu(abpy)PF ] with Cp Co, was used for all
6
n
2
NO reactivity studies. Black powders of [Cu(abpy)] were
2
n
dosed with either a mixture of NO (1%) in dry air (99%) or a
2
mixture of NO (2%) in dry N (98%) at room temperature for
2
2
variable amounts of time. Solid [Cu(abpy)] is insoluble in
n
water and organic solvents. After exposure to NO , the
resulting green powders become soluble in most polar organic
2
major ion observed in positive mode exhibited an m/z value of
+
solvents such as acetonitrile (CH CN) to afford a dark purple/
429, corresponding to Cu(azpy)
of powders of Cu(azpy) to NO
Cu(azpy)
corresponding to [Cu(azpy)
2
(Figure S4). After exposure
gas, the ESI-MS spectrum of
3
black solution. Analysis of the headspace of a sample of
2
2
[
Cu(abpy)] after exposure to an atmosphere of 2% NO in N
changes. A new ion with a m/z of 491,
2
n
2
2
+
reveals the presence of NO gas (approximately 0.6 mol %;
Figure 1), as determined by mid-IR tunable diode laser
2
NO
3
] , emerges (Figure S5), in
addition to an ion at 308 m/z, corresponding to the formation
of [Cu(azpy)NO3]+ (Figure S6). Fragmentative collision-
induced dissociation (CID) performed on the ion at 491 m/z
resulted in the loss of one of the azpy ligands, and the complex
2
+
0
+
fragmented into [Cu (azpy )NO ] . This observation implies
3
II
that the nitrate anion is coordinated to the Cu center and is
more strongly bound to the metal center than one of the azpy
ligands. This strong coordination of nitrate could facilitate the
fragmentation of the polymer chain upon NO exposure.
2
Reduction of the powder obtained through exposure of
[
Cu(abpy)] to NO gas with cobaltocene (Cp Co) results in
n 2 2
the precipitation of a black solid and yellow supernatant. Slow
vapor diffusion of pentane into the dichloromethane/CH CN
3
supernatant held at −20 °C afforded yellow needles of
III
−
cobaltocenium nitrate (Co Cp NO ; Cp = C H ) as
2
3
5
5
Figure 1. Mid-IR laser absorption analysis of the gas product of
confirmed by single-crystal X-ray diffraction (Figure S8). The
[
Cu(abpy)]n dosed with NO2 (red). The strong characteristic
isolation of a nitrate salt further verifies the oxidation of NO
2
−
1
−
absorption of NO appears near 1920.71 cm . In this example, the
to NO by the metallopolymer. We obtained crystals of
3
III
final NO mole fraction in the reactor headspace was determined to be
Co Cp NO regardless of whether the reaction with NO was
2
3
2
6
150 ppm. As a control, the 2% NO /N mixture was also introduced
2 2
performed in dry air or dry N . The crystallization of
2
to the reactor without [Cu(abpy)] (purple). The background NO
n
Cp CoNO under O -free conditions indicates that all three
2
3
2
mole fraction, determined from this control test, was less than 100
ppm.
−
oxygen atoms in NO3 originate from the NO and not from
O . Confirmation of the origin of the oxygen atoms in NO
2
−
2
3
was obtained by IR spectroscopy analysis of three samples of
−
1
absorption near 1920 cm . The evolution of NO gas is very
[Cu(abpy)] dosed with different gas mixtures: one was dosed
n
fast, occurring within the first 0.2 s of NO exposure. Under
with only 2% NO in N , one with 2% NO in N and codosed
2
2
2
2
2
1
6
18
the conditions used for monitoring, the NO concentration in
the reaction headspace reaches about 0.2 mol % in the first 0.2
s (Figure S1).
with O , and one codosed with O . The IR spectra of all
2
2
three samples (Figure S9) are identical: no differences could be
observed for samples with and without oxygen exposure, and
1
8
Several experiments were carried out to identify the other
nitrogen oxides generated from the reaction of the metal-
lopolymer [Cu(abpy)] with NO . The reaction products were
no isotopic shifts were observed in any peaks when O was
2
introduced into the system, confirming that the oxygens in
−
NO3 are derived from NO2.
n
2
dissolved in CH CN and analyzed by electrospray-ionization
We probed the solid-phase−gas-phase reaction between
3
mass spectrometry (ESI-MS, see Supporting Information).
The most intense peak in the spectrum in negative mode is an
ion at 61 m/z, corresponding to NO3− (Figure S2). Of the ion+s
observed in positive mode, one corresponds to Cu(abpy)2
[Cu(abpy)] and NO by a variety of spectroscopic techniques.
n
2
Powders of [Cu(abpy)] display a broad absorbance around
n
−1
6
∼2500 cm in the mid-infrared region (Figure S10). This
absorbance is the low-energy tail of the band we assign as a
predominantly ligand-based intervalence charge transfer
(
431 m/z, Figure S3), indicating fragmentation of the polymer
7
chain upon exposure to NO . We also observe adducts of
copper, azobispyridine ligand, and NO . The ESI-MS
(IVCT) band. This IVCT band is absent in the IR spectrum
2
−
of [Cu(abpy)] after NO dosing (Figure S10), suggesting that
3
n
2
indicates that [Cu(abpy)] is oxidized by NO , and the copper
the product no longer possesses radical abpy ligands. Upon
n
2
−
speciates as a NO3 adduct. No nitrate is observed in the ESI-
MS of acetonitrile saturated with 2% NO in N .
NO dosing, we also observe the emergence of a new peak at
2
−
1
1273 cm (Figure S10), which has been previously attributed
2
2
−
8
To better understand the metallopolymer’s reactivity with
to coordinated nitrate (NO ) in anhydrous cupric nitrate.
3
6
NO , we carried out similar studies with (Cu(azpy) ) (1)
Changes in electronic structure after NO exposure were
2
2
2
(
[
azpy = phenylazo-2-pyridine), a molecular analogue of
observed by electron paramagnetic resonance (EPR) spectros-
Cu(abpy)] where one pyridyl ring per Cu center is replaced
copy. The EPR spectrum of [Cu(abpy)] features a broad peak
n
n
by a phenyl ring to prevent bridging to another Cu center.
Here, the ligand-based mixed valence is formally designated as
Cu (azpy ) . Before exposure of Cu(azpy) to NO , the
with a g value of 2.08, corresponding to radical abpy ligands
with possible contribution from the copper centers due to
+
0.5−
6
6
electronic delocalization. The solid-state EPR spectrum of
2
2
2
B
DOI: 10.1021/acs.inorgchem.9b01190
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Cu(abpy)] after 16 h of NO (2%) exposure reveals that this
Article
[
PF ] : the Cu metal centers appear to be more oxidized after a
bulk reduction of the material, resulting in
n
2
6 n
broad, symmetrical signal in [Cu(abpy)] diminishes upon
n
1
+Δ
−(1+Δ
exposure to NO . We also observe the emergence of a new
[Cu (abpy
)] , where Δ > δ. Although rare, a similar
n
2
II
signal with characteristic rhombic Cu spectral shape (Figure
S12A). There is literature precedent for disproportionation of
NO on electron-rich surfaces, and in fact, Addison et al.
report the isolation of Cu (NO ) and NO gas when copper
phenomenon has been observed in molybdenum and tungsten
compounds with sulfur-based redox noninnocent ligands,
wherein a net oxidation of the compound resulted in a
9
10
2
1
6−19
II
reduction of the metal center.
Dosing [Cu(abpy)] with
n
3
2
NO results in a dramatic blue-shifting of the rising edge
metal is treated with NO in the form of liquid N O .
2
2
2
4
energy to 8986.2 eV. Thus, the reaction of [Cu(abpy)] with
Cu K-edge X-ray absorption spectroscopy (XAS) was used
to further evaluate the oxidation state of Cu in samples of
n
NO yields copper species with rising edge energies similar to
that of the Cu (bpy) (BF ) (8986.3 eV, Figure 2B),
indicating that the oxidation states of the products of NO
exposure are most reasonably formulated as Cu species.
Combining evidence from IR spectroscopy, EPR, and XAS,
we propose that [Cu(abpy)] reacts with four equivalents of
2
II
[
Cu(abpy)] before and after NO dosing, as well as in
2
4 2
n
2
[
Cu(abpy)PF ] . The Cu K rising edge region is dominated by
2
6
n
II
Cu 1s → 4p+ continuum transitions (∼8979 eV) and is
therefore strongly modulated by the effective nuclear charge
1
1−14
n
(
Zeff) on Cu.
The rising edge of [Cu(abpy)PF6]n,
NO gas per copper center, where NO oxidizes both the Cu
2
2
measured as the maximum of the first derivative, occurs at
−
and the abpy ligand and disproportionates to form NO3 and
NO. Although approximate oxidation state assignments are
given below, we note that there is considerable electronic
delocalization between Cu and the abpy ligand, as discussed
above:
an energy of 8982.6 eV and is very similar in energy and shape
15
to that of the molecular model compound [Cu(azpy) ][PF ],
2
6
which has a slightly higher rising edge energy of 8983.4 eV.
The rising edge of both [Cu(abpy)PF ] and [Cu(azpy) ]-
6
n
2
1
5
[
[
PF6] occur at an energy higher than that of [Cu(bpy) ]-
2
I
−
II
0
−
PF ] (bpy = 2,2′-bipyridine), indicating an increase in Z on
6
eff
Cu (abpy ) + 4NO → Cu (abpy )(NO ) + 2NO
2
3
2
Cu as the bipyridine ligand is replaced with more redox-active
azpy or abpy ligands, indicating that [Cu(abpy)PF ] is better
Solid [Cu(abpy)] has a room-temperature conductivity of
n
6
n
−
1
−1
represented as [Cu1 (abpy )PF ] . The rising edge of the
+δ
−δ
0
.18 S·cm , which increases up to 0.46 S·cm upon heating
6
n
to 125 °C, and an activation energy for conduction of 98
reduced species [Cu(abpy)] shows a distinct change in shape
n
6
,20
meV. Upon exposing powders of [Cu(abpy)] to NO (2%)
with a slight increase in rising edge energy (8982.9 eV, Figure
n
2
for 1 h, the room-temperature conductivity of the material
2
A). Remarkably, this shift in rising edge energy is indicative of
−
2
−1
drops to 8.5 × 10 S·cm . After 16 h of exposure, the room-
an increase in the Zeff on Cu upon reduction of [Cu(abpy)-
−
5
−1
temperature conductivity value decreases to 6.4 × 10 S·cm .
Likewise, the activation energy increases up to 290 meV upon
NO dosing. Electrical conductivity in [Cu(abpy)] is thought
2
n
to arise from electron hopping between radical mixed-valence
6
abpy ligands. From the EPR and IR spectra, we infer that the
redox reaction between NO and [Cu(abpy)] results in a loss
2
n
of mixed valency. A decrease in conductivity upon NO2
exposure is consistent with this interpretation and confirms
the loss of electronic communication across the material.
We also observe changes in the surface area of [Cu(abpy)]n
upon NO exposure. Fine powders of [Cu(abpy)] have a
2
n
2
−1
6
Brunauer−Emmett−Teller (BET) surface area of 90 m ·g .
Concomitant with loss of conductivity, we also observe a
complete loss of porosity after NO dosing for 16 h (Figure 3).
2
The observed lack of porosity in NO -dosed [Cu(abpy)] is
2
n
I
Figure 2. Normalized Cu−K edge XAS spectra of (A) [Cu (abpy)-
I
PF ] (teal), [Cu(abpy)] (blue), and Cu (bpy) PF (bpy = 2,2′-
Figure 3. Nitrogen isotherms measured at 77 K of [Cu(abpy)]n
6
n
n
2
6
I
II
bipyridine; orange), a Cu standard, and (B) Cu (bpy) (BF )
purple), a Cu standard, and [Cu(abpy)] after exposure to NO
before exposure to NO gas (blue), after NO exposure (red), and
2
4
2
2
2
II
(
after regeneration of the material by Cp Co reduction (green).
n
2
2
2
2
2
gas for 24 h (red).
Surface areas are 90 m /g, ∼0 m /g, and 70 m /g, respectively.
C
DOI: 10.1021/acs.inorgchem.9b01190
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
consistent with the oxidation of the material to a cationic
species associated with NO3− anions and likely also to the
fragmentation of the polymer chains upon gas exposure.
As the reaction between [Cu(abpy)] and NO is a redox
reaction, we sought to regenerate [Cu(abpy)]n from the
oxidized product using a chemical reductant. The addition of a
indicating that the abpy ligands are actively engaged in the
redox reactions of these materials. The redox reaction between
NO and [Cu(abpy)] results in the disproportionation of
2
n
NO into nitrate and NO gas, as evidenced by vibrational
n
2
2
spectroscopy and single-crystal X-ray diffraction. EPR and XAS
provide evidence for the oxidation of both the ligand and the
copper center upon reaction of [Cu(abpy)] with NO . Upon
solution of Cp Co to a solution of the polymer after exposure
2
n
2
to NO results in the isolation of black powders with properties
exposure to NO , the metallopolymer’s room-temperature
conductivity value drops by four orders of magnitude as it loses
2
2
reminiscent of [Cu(abpy)] . Inductively coupled plasma
n
atomic emission spectroscopy (ICP-AES) and combustion
analysis reveal that the approximate formula of the black
its mixed-valence character. Additionally, NO dosing causes
the metallopolymers to completely lose porosity. Lastly,
[Cu(abpy)]n metallopolymers can be regenerated after
2
powders is [Cu(abpy)] (see Supporting Information). The
n
solid-state EPR spectrum of the reformed polymer shows a
broad peak with a g value of 2.08, similar to that of
oxidation by NO by chemical reduction, recovering much of
2
the electrical conductivity, porosity, and optical properties of
the parent polymer. These promising findings make [Cu-
(abpy)] a good platform for developing materials for NO
[
Cu(abpy)] (Figure S13).
To confirm that we successfully regenerated the [Cu-
n
n
2
(
abpy)] polymer’s properties upon chemical reduction after
sensing and sequestration.
n
exposure to NO , we measured the optical, electronic, and gas
2
sorption properties of the reformed material. The fingerprint
region of the IR spectrum of the reformed material matches
that of the original polymer (Figure S14). Significantly, we
observe the return of the low-energy tail of the IVCT band in
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.9b01190.
■
*
S
the IR spectrum that disappeared upon NO exposure. The re-
2
emergence of the IVCT indicates the reformation of radical
abpy ligands upon reduction.
Experimental descriptions, synthetic procedures, and
material characterization (PDF)
The regenerated material has a room-temperature con-
ductivity (7.8 × 10− S·cm ) and an activation energy for
2
−1
AUTHOR INFORMATION
Corresponding Authors
*E-mail: waymouth@stanford.edu.
*E-mail: hemamala@stanford.edu.
*E-mail: ritis@slac.stanford.edu.
conductivity (160 meV) similar to that of [Cu(abpy)]
generated from [Cu(abpy)PF ] (0.18 S·cm and 98 meV,
■
n
−
1
6
n
respectively). Furthermore, we find that the regenerated
material regains a significant fraction of the porosity with a
2
−1
2
−1
BET surface area of 70 m ·g (vs 90 m ·g for [Cu(abpy)]n).
We have shown that the porosity of [Cu(abpy)] arises from
ORCID
n
expulsion of charge-balancing anions upon reduction of the
Naomi E. Clayman: 0000-0002-4894-2174
Benjamin D. Matson: 0000-0001-5733-0893
Shengkai Wang: 0000-0003-0947-4643
Ritimuka Sarangi: 0000-0002-2764-2279
Hemamala I. Karunadasa: 0000-0003-4949-8068
Robert M. Waymouth: 0000-0001-9862-9509
Author Contributions
N.E.C and M.A.M. contributed equally.
Notes
The authors declare no competing financial interest.
−
−
F −
[
Cu(abpy)X] (X = Br , PF , BAr ) from which it is
n 6 4
6
generated. The slightly lower conductivities and surface areas
of the regenerated materials may be due to the templating
−
effect mediated by the extrusion of different anions (NO vs
3
−
PF ) upon reduction. To test this hypothesis, we prepared a
6
sample of [Cu(abpy)] from [Cu(abpy)NO ] to see if the
n
3 n
porosity of the reformed material can be attributed to the
⊥
anion templating effect. Reduction of [Cu(abpy)NO ] yields
3
n
2
−1
[
Cu(abpy)] with a BET surface area of 60 m ·g (Figure
n
S15).
The lower porosity of the [Cu(abpy)] generated from
n
[
(
Cu(abpy)NO3]n compared to that generated from [Cu-
ACKNOWLEDGMENTS
■
abpy)PF6] is consistent with the previously observed
n
N.E.C. and R.M.W. thank the Office of Naval Research (ONR
N000141410551) and the Center for Molecular Analysis and
Design (CMAD) for a graduate fellowship. Work by M.A.M.,
A.H.S, and H.I.K. was funded by an NSF CAREER award
(DMR-1351538). M.A.M. thanks CMAD, the National
Science Foundation (NSF; award DGE-114747), and
Stanford’s Diversifying Academia, Recruiting Excellence
Program for fellowships. B.D.M. was supported by the
Precourt Institute for Energy (2017-4-Waymouth). Use of
the Stanford Synchrotron Radiation Lightsource, SLAC
National Accelerator Laboratory, is supported by the U.S.
Department of Energy, Office of Science, Office of Basic
Energy Sciences under Contract DE-AC02-76F00515. Single
crystal X-ray diffraction was performed on Beamline 11.3.1 at
the Advanced Light Source, which is a DOE Office of Science
User Facility under Contract DE-AC02-05CH11231. We
thank Prof. Matteo Cargnello and Dr. Michael Aubrey for
−
−
6
templating effect because PF6 is larger than NO . Because
we expect the polymer to fragment upon NO3 coordination
to the Cu centers, this templating effect may not be as strong
when reforming [Cu(abpy)] from the NO reaction product
3
−
n
2
2
−1
mixture. The 10 m ·g difference in surface area between the
[Cu(abpy)] polymer generated from [Cu(abpy)NO ] and
n
3 n
the [Cu(abpy)] polymer reformed from the NO reaction
may also be within experimental error as the surface area of
these soft materials is very sensitive to handling conditions.
n
2
6
CONCLUSIONS
■
In conclusion, we report the reactivity of the porous and
electrically conductive copper azobispyridine metallopolymer,
[
Cu(abpy)] , with NO . Intriguingly, XAS analysis indicates
n 2
that the oxidation state of the copper ions increases upon
reduction of [Cu(abpy)PF6]n to generate [Cu(abpy)]n,
D
DOI: 10.1021/acs.inorgchem.9b01190
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
helpful discussions. We thank Dr. Abraham Saldivar Valdes,
Dr. Michael Aubrey, Dr. Matthew D. Smith, Kurt Lindquist,
and Katherine Walker for experimental assistance. We thank
Prof. Edward I. Solomon and Prof. Ronald K. Hanson for
access to equipment. XAS measurements were performed at
beamline 7-3 at the Stanford Synchrotron Radiation Light-
source (SSRL).
(18) Coyle, C. L.; Harmer, M. A.; George, G. N.; Daage, M.; Stiefel,
2‑
2‑
E. I. Conversion of [MoS4] to [Mo S (μ-S) (S ) ] by Organic
2
2
2
2 2
Disulfides: The Mechanism of an Induced Redox Reaction. Inorg.
Chem. 1990, 29, 14−19.
2
−
(
19) Sarkar, S.; Ansari, M. A. Conversion of WOS into [W O (μ-
3 2 2
2−
S) (S ) ] and vice-versa by internal redox processes induced by I2
2
2
2
2−
and Sx . J. Chem. Soc., Chem. Commun. 1986, 324−325.
(
20) Shao, Q.; Jiang, S. Effect of Carbon Spacer Length on
Zwitterionic Carboxybetaines. J. Phys. Chem. B 2013, 117, 1357−
366.
1
REFERENCES
■
(
1) Huang, W.; Zhuang, X.; Melkonyan, F. S.; Wang, B.; Zeng, L.;
Wang, G.; Han, S.; Bedzyk, M. J.; Yu, J.; Marks, T. J.; Facchetti, A.
UV−Ozone Interfacial Modification in Organic Transistors for High-
Sensitivity NO Detection. Adv. Mater. 2017, 29, 1701706.
2
(
2) Pearce, R.; Iakimov, T.; Andersson, M.; Hultman, L.; Spetz, A.
L.; Yakimova, R. Epitaxially grown graphene based gas sensors for
ultra sensitive NO detection. Sens. Actuators, B 2011, 155, 451−455.
2
(
3) Ferroni, M.; Guidi, V.; Martinelli, G.; Sacerdoti, M.; Nelli, P.;
Sberveglieri, G. MoO -based sputtered thin films for fast NO2
3
detection. Sens. Actuators, B 1998, 48, 285−288.
(
4) Xia, H.; Wang, Y.; Kong, F.; Wang, S.; Zhu, B.; Guo, X.; Zhang,
J.; Wang, Y.; Wu, S. Au-doped WO -based sensor for NO detection
3
2
at low operating temperature. Sens. Actuators, B 2008, 134, 133−139.
(
5) Andringa, A.-M.; Piliego, C.; Katsouras, I.; Blom, P. W. M.; de
Leeuw, D. M. NO Detection and Real-Time Sensing with Field-
2
Effect Transistors. Chem. Mater. 2014, 26, 773−785.
(
6) Clayman, N. E.; Manumpil, M. A.; Umeyama, D.; Rudenko, A.
E.; Karunadasa, H. I.; Waymouth, R. M. Carving Out Pores in Redox-
Active One-Dimensional Coordination Polymers. Angew. Chem., Int.
Ed. 2018, 57, 14585−14588.
(
7) D’Alessandro, D. M.; Keene, F. R. Current trends and future
challenges in the experimental, theoretical and computational analysis
of intervalence charge transfer (IVCT) transitions. Chem. Soc. Rev.
2
(
006, 35, 424−440.
8) Addison, C. C.; Gatehouse, B. M. The Infrared Spectra of
Anhydrous Transition-metal Nitrates. J. Chem. Soc. 1960, 613−616.
9) Garribba, E.; Micera, G. The Determination of the Geometry of
Cu(II) Complexes: An EPR Spectroscopy Experiment. J. Chem. Educ.
006, 83, 1229−1232.
10) Addison, C. C. Dinitrogen Tetroxide, Nitric Acid, and Their
Mixtures as Media for Inorganic Reactions. Chem. Rev. 1980, 80, 21−
9.
11) Cho, J.; Sarangi, R.; Kang, H. Y.; Lee, J. Y.; Kubo, M.; Ogura,
(
2
(
3
(
T.; Solomon, E. I.; Nam, W. Synthesis, Structural, and Spectroscopic
Characterization and Reactivities of Mononuclear Cobalt(III)−
Peroxo Complexes. J. Am. Chem. Soc. 2010, 132, 16977−16986.
(
12) Sarangi, R. X-ray absorption near-edge spectroscopy in
bioinorganic chemistry: Application to M−O systems. Coord.
2
Chem. Rev. 2013, 257, 459−472.
(
13) Sarangi, R.; Cho, J.; Nam, W.; Solomon, E. I. XAS and DFT
Investigation of Mononuclear Cobalt(III) Peroxo Complexes:
Electronic Control of the Geometric Structure in CoO2 versus
NiO Systems. Inorg. Chem. 2011, 50, 614−620.
2
(
14) DuBois, J. L.; Mukherjee, P.; Stack, T. D. P.; Hedman, B.;
Solomon, E. I.; Hodgson, K. O. A Systematic K-edge X-ray
Absorption Spectroscopic Study of Cu(III) Sites. J. Am. Chem. Soc.
2
(
(
000, 122, 5775−5787.
15) Datta, D.; Chakravorty, A. Bis(2-(phenylazo)pyridine)copper-
I) and -copper(II): Ligand π Acidity and High Formal Potential of
the Copper(II)-Copper(I) Couple. Inorg. Chem. 1983, 22, 1085−
090.
16) Stiefel, E. I.; Halbert, T. R.; Coyle, C. L.; Wei, L.; Pan, W.-H.;
1
(
Ho, T. C.; Chianelli, R. R.; Daage, M. Molecules, clusters, solids and
catalysts in early transition metal sulphide systems. Polyhedron 1989,
8
(
, 1625−1629.
17) Yang, X.; Freeman, G. K. W.; Rauchfuss, T. B.; Wilson, S. R.
Dithiocarbonate route to 1,2-dithiolene complexes of molybdenum
and tungsten. Inorg. Chem. 1991, 30, 3034−3038.
E
DOI: 10.1021/acs.inorgchem.9b01190
Inorg. Chem. XXXX, XXX, XXX−XXX