Solution: Versus solid-state dual emission of the Au(i)-alkynyl diphosphine complexes via modification of polyaromatic spacers

Article abstract of DOI:10.1039/c9nj03426a

Single molecule luminophores capable of multiple emissions are essential for the development of new materials with unconventional photophysical behavior. In this work, a family of diphosphine ligands PPh₂-PAH-PPh₂ with variable polya

Full text of DOI:10.1039/c9nj03426a

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Solution versus Solid-State Dual Emission of the Au(I)-Alkynyl
Diphosphine Complexes via Modification of Polyaromatic Spacers
Received 00th January 20xx,
Accepted 00th January 20xx
Andrey Belyaev,*a Ilya Kolesnikov,b Alexei S. Melnikov,c Vladislav V. Gurzhiy,d Sergey P. Tunik,e Igor
O. Koshevoy*a
DOI: 10.1039/x0xx00000x
Single molecule luminophores capable of multiple emissions, are essential for the development of new materials with
unconventional photophysical behavior. In this work, a family of the diphosphine ligands PPh2–PAH–PPh2 with variable
polyaromatic hydrocarbon (PAH) spacer (PAH = 9,10-anthracene L1, 1,4-naphthalene L2, 2,6-naphthalene L3, and their
diethynyl congeners L4–L6) were employed to prepare gold(I) complexes (RC2Au)PPh2–PAH–PPh2(AuC2R) (1–22),
containing a selection of alkynyl groups. Investigation of their optical properties indicates that compounds with
anthracene-based diphosphines (1–4 and 13–16) display only 1IL (ππ*) fluorescence with Φem up to 93%. The naphthalene
and diethynyl-naphthalene diphosphine complexes (5–12 and 17–22), however, demonstrate panchromatic emission in
the solid state and in solution featuring well-separated low and high energy signals, which originate from 1IL (ππ*) and 3IL
(ππ*) transitions along with certain contribution from metal to ligand and ligand to ligand charge transfers.
“forbidden” phosphorescence (T1→S0). However, the reports
of pure room temperature fluorescence (S1→S0) from the
molecules containing gold atoms indicate that the presence of
Introduction
The nature of the ground and excited states of luminescent
molecules primarily determines their photophysical
characteristics, such as absorption and emission, the rates of
radiative and non-radiative processes and, consequently, the
excited state lifetimes. Rational design of the emitting
molecular skeleton is expected to provide control over the
energies of electronic transitions by manipulating the frontier
molecular orbitals. Such target modulation of luminescent
properties results in solvatochromism, thermally activated
delayed fluorescence, stimuli-responsive behavior, long-lived
phosphorescence, panchromatic emission, which are suitable
this heavy element does not necessarily ensure fast ISC rate,
and the nature of the ligands also plays an important role in
the excited-state dynamics and deactivation mechanisms.3a, 4
Conversely, in the case of moderate ISC rate constant,
compatible with that of fluorescence relaxation, room
temperature fluorescence/phosphorescence dual emission
(S1+T1 → S0) can be observed for this sort of gold compounds.
Construction of such emitters remains a challenge due to the
need to keep a delicate balance of populating the S1 and T1
excited states, but potential benefits of this photophysical
phenomenon comprise ratiometric oxygen and pH
for
a
number of practical applications including
electroluminescent devices, sensors and bioimaging.1,2
6
monitoring,5
white-light
fluorescence/phosphorescence lifetime imaging.7
generation,5b,
and
One approach to novel light emitting materials involves the
incorporation of late transition metal atoms (OsII, ReI, IrIII, PtII
and AuI/III) into an organic chromophore.3 In particular, the
formation of the σ-bond between carbon skeleton and the
gold(I) ion by means of heavy atom effect enhances spin-orbit
coupling (SOC) and accelerates the rate of intersystem crossing
(ISC, i.e. singlet-triplet transition S1→T1). This leads to a rapid
population of the triplet excited state and further can induce
Dually emissive gold(I) organometallic species predominantly
have low nuclearity and belong to the well-studied LAuX type
with linear two-coordinate geometry of the metal center.
These complexes are conventionally constructed of isolobal to
the proton LAu+ (L = phosphine or N-heterocyclic carbene)
cationic fragments,8 which are complemented by σ-bonded
aromatic,4c, 9 alkynyl,10 or halide11 X ligands. Among accessible
variations of the constituents, phosphine-alkynyl complexes
(R3PAu–C≡C)n–R´ prevail in the family of dual gold(I)
luminophores due to facile synthesis and functionalization
(Figure 1A). Their photophysical properties are mainly
regulated by intraligand transitions localized on the alkynyl
ligands, which may contain a wide range of conjugated organic
groups. As a representative illustration, simultaneous ligand-
centered dual fluorescence (prompt and delayed) and
phosphorescence of the conjugated (poly)phenylethylene-
a. Department of Chemistry, University of Eastern Finland, Joensuu, 80101, Finland.
b. Center for Optical and Laser materials research, d. Crystallography Department
and e.Institute of Chemistry, St. Petersburg State University, 198504, St.
Petersburg, Russia.
c. St. Petersburg State Polytechnical University, 195251 St. Petersburg, Russia
* Authors for correspondence
E-mail:
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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gold(I) phosphine complexes was described by the group of by varying the length of the oligophenylene spacer (Fig. 1B).6a,
View Article Online
12
Che.10a Another molecular design, which is less common,
Moreover, electronic properties of DtOhIe: 10a.1n0c3i9ll/aCr9yNJa0l3k4y2n6yAl
substituents (Figure 1C) were shown to affect significantly the
rate of ISC process by means of altering the contribution of
charge transfer transitions, and therefore influence the
probability of singlet vs triplet emission.13
implies the incorporation of a π-
In the continuation of our studies, herein, we employ a family
of diphosphine ligands based on the polyaromatic spacers
(anthracene, naphthalene and their diethynyl derivatives, Fig.
1D). These P-donor modified chromophores were utilized for
the preparation of novel gold(I) alkynyl complexes, the
luminescence behavior of which was analyzed in solution and
in the solid state to correlate with their molecular structures.
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Experimental section
General comments. 9,10-bis-(diphenylphosphino)anthracene
(L1),4a (AuC2CR)n (R = Ph; 4-C6H4-X, X = CF3, OMe, NH2, NMe2,
Ph; C(CH3)2OH; C6H10OH; C(С6H5)2OH),14 diethynylarenes
(arene = 9,10-anthracene; 1,4- and 2,6-naphthalene)15 were
synthesized according to the published procedures.
Tetrahydrofuran (THF) and diethyl ether were distilled over
Na-benzophenone ketyl under a nitrogen atmosphere prior to
use. Other reagents and solvents were used as received. The
solution on 1H, 31P{1H} and 1H–1H COSY NMR spectra were
recorded on a Bruker 400 Avance spectrometer. Mass spectra
were determined with
a Bruker maXis HD ESI-QTOF
instruments in the ESI+ mode. Microanalyses were carried out
in the analytical laboratories of the University of Eastern
Finland and of Saint-Petersburg State University.
Photophysical measurements. Absorption spectra were
recorded using a Lambda 1050 and Shimadzu UV 1800
spectrophotometers; excitation and emission spectra in
solution and solid-state were measured on a Fluoromax 4 and
Fluorolog 3 spectrofluorimeters. LED (maximum of emission at
265 nm, 340 nm and 390 nm) were used in pulse mode to
pump luminescence in fluorescence lifetime measurements
(pulse width ~1 ns, repetition rate 100 MHz to 10 kHz). DTL-
399QT Laser-export Co. Ltd "(351 nm, 50 mW, pulse width 6 ns
repetition rate 0.01-1 kHz), MUM monochromator (LOMO, 1
nm bandwidth), counting head for photons H10682,
Figure 1. The representative families of previously studied dually emissive
phosphine-gold(I) alkynyl complexes (A-C), and the scope of the current work
(D).
chromophore spacer into the diphosphine moiety. Utilizing
this strategy, we reported a series of dinuclear gold(I) alkynyl
complexes based on oligophenylene diphosphine ligands, The
rate of ISC for these compounds systematically decreases upon
an increase of the effective distance between the heavy gold
atom and the center of the chromophore fragment, which
allows for fine-tuning the fluorescence/phosphorescence ratio
Scheme
1.
Polyaromatic
phosphine
ligands
and
their
gold(I)
alkynyl
complexes
1–22
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room temperature and was stirred overnight. Then the
solvents were evaporated, the solid residue was washed with
methanol (3 × 20 ml) and vacuum dried. Crude L4 was passed
through a silica gel (150 mesh, 2.5 × 15 cm, eluent
CH2Cl2/hexanes 1:1 v/v). Pure sample was obtained by
additional treatment of L4 with activated charcoal in
dichloromethane and recrystallization by slow evaporation of a
(Hamamatsu) and digital time transducer P7887 (FAST
ComTec GmbH) were used to measure the phosphorescence
lifetime. The emission quantum yield in solution was
determined by Vavilov’s method16 using LED (385 nm,
continuous mode) and Xenon lamp pumping, with coumarine
102 (Φem = 0.76) and tryptophan (Φem = 0.13) as standards.
The solutions were carefully degassed by purging Ar for 25
min. The integration sphere Quanta-φ (6-inches) was used to
measure the solid state emission quantum yields for the
complexes by absolute method.
o
toluene/CH2Cl2 solution of L4 at +5 C to afford bright yellow
needles (1.24 g, 63%). 31P{1H} NMR (CDCl3, 298 K; δ): –32.7 (s).
1H NMR (CDCl3, 298 K; δ): 8.55–8.57 (m, 1,4,5,8-H C14H8, 4H),
7.81–7.85 (m, ortho-H Ph, 8 H), 7.57–7.59 (m, 2,3,6,7-H C14H8,
4H), 7.41–7.47 (m, meta+para-H Ph, 12H). Anal. Calc. for
C42H28P2: C, 84.84; H, 4.75. Found: C, 84.64; H, 4.81.
1,4-Bis-(diphenylphosphino)naphthalene (L2).
A
1.6
M
solution of n-BuLi in hexanes (2.8 mL, 4.5 mmol) was added
dropwise to a solution of 1,4-dibromonaphtalene (0.65 g, 2.3
mmol) in diethyl ether (45 ml) at 0 oC. The resulting suspension
was stirred at this temperature for 30 min. and then allowed
to reach room temperature. It was stirred for an additional
hour, then at was treated dropwise with neat PPh2Cl (1.04 g,
4.7 mmol). Stirring was continued for 3 hours and then the
reaction was quenched with a saturated aqueous solution of
NH4Cl (30 ml). Dichloromethane (30 ml) was added to dissolve
organic solids. The layers were separated and the aqueous
layer was further extracted with dichloromethane (3 x 20 ml).
The combined organics were dried over Na2SO4, filtered and
evaporated. The resulting yellow oil was purified by column
chromatography (silica gel, 150 mesh, 2.5 × 15 cm, eluent
CH2Cl2/hexanes 1:4 v/v) and further recrystallized by slow
evaporation of a hexanes/CH2Cl2 solution of L2 at +5 oC to
afford colorless crystalline material (0.62 g, 55%). 31P{1H} NMR
1,4-Bis-[(diphenylphosphino)ethynyl]naphthalene
(L5).
Prepared analogously to L4 from 1,4-diethynylnaphtalene
(0.60 g, 3.4 mmol). Recrystallization by gas-phase diffusion of
o
diethyl ether into a dichloromethane solution of L5 at +5 C
afforded colorless crystalline material (1.34 g, 73%). 31P{1H}
1
NMR (CDCl3, 298 K; δ): –33.3 (s). H NMR (CDCl3, 298 K; δ):
8.35-8.37 (m, 2,5-H C10H6, 2H), 7.73-7.78 (m, ortho-H Ph and
3,6-H C10H6, 10H), 7.59–7.61 (m, 3,4-H C10H6, 2H), 7.39–7.44
(m, meta+para-H Ph, 12H). Anal. Calc. for C38H26P2: C, 83.81; H,
4.81. Found: C, 83.61; H, 4.75.
2,6-Bis-[(diphenylphosphino)ethynyl]naphthalene
(L6).
Prepared analogously to L4 from 2,6-diethynylnaphtalene
(0.60 g, 3.4 mmol). Recrystallization by slow evaporation of a
o
methanol/CH2Cl2 solution of L6 at +5 C afforded light yellow
crystalline material (1.13 g, 61%). 31P{1H} NMR (CDCl3, 298 K;
1
δ): –33.7 (s). H NMR (CDCl3, 298 K; δ): 8.04 (s, 1,4-H C10H6,
2H), 7.78 (d, 3JHH 8.4 Hz, 3,6-H C10H6, 2H), 7.69–7.74 (m, ortho-
1
(CDCl3, 298 K; δ): –13.4 (s). H NMR (CDCl3, 298 K; δ): 8.45–
3
H Ph, 8H), 7.60 (d, JHH 8.4 Hz, 2,5-H C10H6, 2H), 7.37–7.42 (m,
8.48 (m, 3,6-H C10H6, 2H), 7.44–7.48 (m, 4,5-H C10H6, 2 H),
7.30–7.36 (m, Ph, 20 H), 6.86–6.87 (m, 1,2-H C10H6, 2H). Anal.
Calc. for C34H26P2: C, 82.25; H, 5.28. Found: C 81.98; H 5.34.
meta, para-H Ph, 12H). Anal. Calc. for C38H26P2: C, 83.81; H,
4.81. Found: C, 83.54; H, 4.80.
General procedure for the preparation of complexes 1–22.
(AuC2R)n (0.3 mmol) was mixed with the corresponding
diphosphine (0.16 mmol) in dichloromethane (10 ml). The
reaction mixture was stirred for 45 min in the absence of light.
The resulting solution was filtered through a Celite pad,
vacuum dried and the solid residue was purified by
recrystallization. The crystallization and spectroscopic details
are given in the ESI.
2,6-Bis-(diphenylphosphino)naphthalene
(L3).
Prepared
analogously to L2 from 2,6-dibromonaphtalene (1.00 g, 3.5
mmol). Recrystallization by gas-phase diffusion of diethyl ether
into a dichloromethane solution of L3 at +5 oC afforded
colorless crystalline material (1.08 g, 62 %). 31P{1H} NMR
1
(CDCl3, 298 K; δ): –4.7 (s). H NMR (CDCl3, 298 K; δ): 7.75 (d,
3JHH 8.4, 3,6-H C10H6, 2H), 7.68 (d, 3JHH 8.4 Hz, 2,5-H C10H6, 2H),
7.4–7.35 (m, Ph and 1,4-H C10H6, 22 H). Anal. Calc. for C34H26P2:
C, 82.25; H, 5.28. Found: C, 82.30; H, 5.30.
9,10-Bis-[(diphenylphosphino)ethynyl]anthracene (L4). 9,10-
Diethynyl anthracene (0.75 g, 3.3 mmol) was suspended THF
Result and discussion
Synthesis and characterization
o
(50 ml) and cooled to –78 C. a 1.6 M solution of n-BuLi in
Two families of diphosphine ligands containing polyaromatic
hydrocarbon (PAH) backbones (9,10-anthracene (L1), 1,4-
naphthalene (L2), 2,6-naphthalene (L3), and their PAH-
diethynyl congeners (L4–L6), Scheme 1) were conventionally
hexanes (4.4 ml, 7.0 mmol) was slowly added dropwise. The
o
reaction mixture was warmed to –30 C within ca. 1 h, then
o
cooled to –78 C again and treated dropwise with neat PPh2Cl
(1.52 g, 6.9 mmol). The reaction mixture was allowed to reach
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Figure 2. Molecular views of dimer 1 and polymer 9 (thermal ellipsoids are shown at
prepared in good yields via lithiation of dihalo- or diethynyl
PAH precursors and coupling the metalated derivatives with
stoichiometric amount of PPh2Cl.
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50% probability).
DOI: 10.1039/C9NJ03426A
the dominating signals of positively charged ion signals
generated either by dissociation of alkynyl ligands or by
association of the corresponding molecules with Na+ ions. The
31P{1H} NMR spectra of 1–22 display singlet resonances with
chemical shifts in the ranges 36.3–43.0 ppm (1–12) and 16.4–
17.1 ppm (13–22), which are typical for the gold(I) compounds
containing the related phosphines13 and are virtually
insensitive to the nature of alkynyl ligands. These data indicate
that complexes 1–22 exist in solution in their molecular forms
The dinuclear complexes (RC2Au)PPh2–spacer–PPh2(AuC2R)
were readily obtained reacting (AuC2R)n species with
corresponding bidentate ligands under ambient conditions
(Scheme 1), analogously to a number of earlier reported
17
congener species.13-14, The resulting compounds form two
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series (1–12) and (13–22), which are distinguished by the type
of stereochemically and electronically different phosphine
ligands (tertiary aromatic L1–L3 and ethynyl-aromatic L4–L6,
respectively).
1
of idealized symmetry that is additionally supported by the H
In solution, all the title complexes 1–22 were characterized
NMR spectroscopic patterns, completely compatible with
molecular arrangements shown in Scheme 1.
1
using ESI+ mass spectrometry and H, 31P NMR spectroscopy.
The ESI MS of 1–12 (Fig. S1, Supporting Information) show
Solid-state structures of 1–3, 7, 9, 12, 13 and 19 have been
elucidated by the XRD analysis (Figs. 1, 2 and S2); selected
structural parameters are summarized in Table S2. Complexes
1 and 9 containing –C2Ph ligands display intermolecular Au–Au
interactions to form a dimeric structure and infinite polymeric
The metal-metal distances in 1 (3.092 Å) and 9 (3.212 Å) are
typical for aurophilic bonding frequently encountered in the
crystals of gold(I) phosphine compounds.18
The Au(I) species with hydroxyaliphatic alkynes (2, 3, 7 and 12)
do not feature metallophilic contacts (Figs. 3 and S2).
Alternatively, complexes 2 and 3 with anthracene diphosphine
L1 demonstrate extensive intermolecular O–H…O hydrogen
bonding (O…O separations are 2.76–2.88 Å) that evidently
affects molecular packing for these species (Figs. S2 and S3).
The visible bending of anthracene motif in 1–3 is similar to that
observed for other gold compounds based on L1, and has been
tentatively attributed to intramolecular steric hindrance.4a, 19
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Figure 3. Molecular views of complexes 3, 7 and 12 (thermal ellipsoids are shown at 50% probability).
Figure 4. Molecular views of dimers 13 and 19 (thermal ellipsoids are shown at 50% probability).
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are red shifted in comparison to the parent anthracene, point
to some charge transfer contribution into the emissive excited
state due to the presence of coordinated PPh2 groups. The
luminescence quantum yields for 1–4 of a few percent only
can be attributed to the gold-induced heavy atom effect that
facilitates fast ISC and leads to the population of the dark
triplet state. Furthermore, larger rates of S1→T1 transition are
known to increase the radiationless internal conversion
S1→S0.10e
The emission and excitation characteristics of 2–4 at room
temperature in the solid state resemble those measured in
solution (Fig. 5B). The emission band maxima are slightly red
shifted with respect to the fluid medium, whereas the
quantum yield decreases considerably pointing to effective
aggregation-caused quenching effect, which often operates for
organic luminophores.
In contrast to 2–4, complex 1 displays ca. 40 nm bathochromic
shift of luminescence in the solid state, that is presumably
determined by the dimeric structure and π-stacking of the
anthracene chromophores, see Fig. 1. These intermolecular
interactions apparently raise the ground state energy and
decrease the energy gap between the S0 and S1 states. For all
complexes of this group, the excited state lifetimes fall in the
nanosecond domain that confirms the singlet origin of
emission.
At 77 K the emission bands of 2–4 exhibit vibronic progressions
of ca. 1000-1200 cm-1 without a substantial shift of the band
center that clearly points to intraligand L1 origin of
fluorescence (Fig. S4A). The broad emission of 1 at 77K suggest
that more than one excited state operate upon cooling. This
feature evidently crystal packing effect, i.e. the influence of π-
stacking and metal-metal interactions, as the spectrum of 1 in
frozen solution (CH2Cl2) resembles those of 2–4 (Fig. S4B).
Figure 5. (A) UV-vis absorption (dotted lines) and normalized emission (solid lines)
spectra of 1–4 in CH2Cl2 (298 K, λex = 415 nm); (B) normalized solid-state excitation
(dotted lines) and emission (solid lines) spectra of 1–4 (298 K, λex = 415 nm).
Photophysical properties
Complexes 1–4. The absorption and emission spectra of 1–4
are shown in Fig. 5, while the corresponding data are given in
Table 1. These complexes display similar absorption spectra
which are nearly identical to those of the free diphosphine
ligand L1 and its reported gold(I) compounds.4a, 19b Analogously
to the previous analysis, intense high energy (270 nm) and low
energy (370–470 nm) vibronically structured absorption bands
can be assigned to the π–π* transitions localized within
anthracene rings, though some contribution from σ(Au–P)→
π* into the LE absorptions cannot be excluded.20
Complexes 1–4 are luminescent in solution at room
temperature (Figure 5A). Their emission profiles, small Stokes
shift and the lifetimes of ca. 3 ns fit well with fluorescence
behavior of cationic complexes [Au3(L1)3]3+, [Au4(L1)2(μ-
bipy)2]4+ [Au4(L1)(diethyldithiocarbamate)3]+,4a, 19b, 21 and of the
oxide derivative O=L1.22 Thus, the observed emission of 1–4
has mainly an intraphosphine character (1IL) and is virtually
independent on the nature of ancillary ligands. The
unstructured fluorescence signals for these complexes, which
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Figure 6. Room temperature UV-vis absorption (dotted lines) and normalized emission
View Article Online
(solid lines) spectra of 5–8 (A, λex = 310 nm) and 9–12 (B, λex = 300 nm) in degassed
DOI: 10.1039/C9NJ03426A
CH2Cl2; color-filled profiles correspond to the spectra of 5 (peach, A) and 9 (blue, B) in
5
aerated solutions.
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
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26
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31
32
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34
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49
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51
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55
56
57
58
59
60
Table 1. Photophysical properties of complexes 1–4.
Solution (CH2Cl2, 298 K)
Solid
λabs, nm (ε×10-3, cm-1 M-1)
λema, nm
Φemb, %
τobs, ns
λema, nm 298 K
λem.a, nm 77 K
Φ
emc, %
L1
1
2
277, 355sh, 374, 396, 419
270 (86), 281 sh (57), 368sh (4), 389 (8), 415 (12), 440 (13)
271 (63), 367sh (5), 389 (10), 415 (15), 440 (15)
485
475
3
4
2.3
3
522
489
~554
467, 490,
506sh
464, 488,
522sh
<1%
<1%
3
4
271 (80), 366 (6), 388 (13), 415 (19), 439 (20)
270 (83), 366 (6), 389 (13), 415 (20), 439 (20)
480
480
5
4
3
492
489
<1%
<1%
3.2
477, 508,
545sh
a λex = 415 nm; b measured in degassed solution; c in KPF6 tablet.
Complexes 5–8 and 9–12. Table 2 summarizes photophysical points to a ligand centered (L2 naphthalene backbone) nature
data for the series 5–8 and 9–12, the relevant solution and of this emission. A large Stokes shift together with oxygen
solid-state spectra are presented in Figs. 6, S5 and S6. quenching of LE signal, as depicted in Fig. 5, are indicative of
Changing the 9,10-anthracene backbone in the diphosphine the triplet origin of this band (phosphorescence), while the HE
ligand for the 1,4-naphthalene (L2-based complexes 5–8) or one, which also shows vibronic structure for 9–12 series (Δν
2,6-naphthalene (L3-based complexes 9–12) leads to the ~1200 cm-1) and is not sensitive to the presence of molecular
essential variation of the photophysical behavior of the oxygen, is associated intraligand fluorescence of L2 (5–8) and
resulting gold(I) alkynyl complexes.
L3 (9–12) diphosphines, visibly perturbed for 5–8 by the –
In solution, complexes 5–8 and 9–12 display dual emission, PPh2AuR motifs. Unfortunately, low intensity of luminescence
which comprises the HE band centered at ca. 350 nm and a (Φem < 0.1%) did not allow to determine accurately the
structured LE band with wavelength above 500 nm. Vibronic lifetimes of singlet and triplet excited states to confirm their
progression of the LE band of ca. 1300–1500 cm-1 is normal for multiplicities.
the gold-bound aromatic chromophores9b,
23
and therefore
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9
10
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12
13
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19
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49
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52
53
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60
Table 2. Photophysical properties of complexes 5–12.
Solution (CH2Cl2, 298 K)
Solid
τavc, μs
Φemd, %
λabs, nm (ε×10-3, cm-1 M-1)
λema, nm
λemb, nm 298 K
λem.b, nm 77 K
L2
5
274 (6), 332 (6)
268 (32.5), 280 (32), 296 sh (19), 310 (15),
326 (10)
350, 503, 538, 580
506, 536, 582
511, 524, 540, 590sh
13.2
2
497, 509sh, 536, 580,
632
510, 536, 580sh
498, 510, 536, 578,
630
497, 510, 535, 549,
576
516, 533, 550
6
7
275 (7), 297 (10), 310 (11), 326 (8.5)
274 (6.5), 297 (9.5), 310 (11), 326 (7)
273 (7), 297 (10), 310 (11), 326 (8.5)
351, 501, 536, 583
351, 501, 536, 586
352, 502, 540, 582
2.4
2.1
<1%
<1%
<1%
8
514, 523sh, 553, 600
86.3
L3
9
270 (17), 310 9)
258 (72), 283 (46), 293 (33), 310 (15), 320
(2.3), 336 (2)
478, 520sh, 557,
605sh
475, 521, 554, 605,
664sh
341, 356, 516, 555, 600
488, 524, 555, 605sh
225.9
205.9
<1%
2
258 (72), 275 (19), 288 (16), 298 (11), 320
(2.3), 336 (2)
258 (72), 275 (19), 288 (16), 298 (11), 320
(2.3), 336 (2)
258 (72), 275 (19), 288 (16), 298 (11), 320
(2.3), 336 (2)
340, 356, 373, 514, 555,
604
486sh, 519, 552,
600sh
10
11
12
341, 356, 514, 555, 603
513, 551, 597, 654
509, 548, 593, 648
507, 546, 592, 647
1694.4
1407.4
5
504, 515, 543, 589,
645
342, 357, 517, 557, 603
7
b
c
2
a λex = 310 nm for 5–8 and 300 nm for 9–12; λex = 330 nm; average emission lifetimes for the two-exponential decay determined using the equation τav = (A1τ1
+
A2τ22)/(A1τ1 + A2τ2), where Ai is the weight of the i-exponent; d in KPF6 tablet.
Figure 7. (A) UV-vis absorption spectra of 13–16, color-filled profile corresponds to L4 (CH2Cl2, 298 K); (B) normalized excitation (dotted lines) and emission (solid lines) spectra of
13–16 (CH2Cl2, 298 K); (C) changes of absorption and emission spectra of 16 upon protonation by CF3COOH.
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Table 3. Photophysical properties of complexes 13–16.
View Article Online
DOI: 10.1039/C9NJ03426A
Solution (CH2Cl2, 298 K)
Solid
5
6
λemb, nm
298 K
λemb, nm
77 K
Φem
%
,
τobs,
ns
λabs, nm (ε×10-3, cm-1 M-1)
λema, nm
Φem, %
τobs, ns
7
8
9
-
-
L4
13
273, 381, 406, 430, 458
-
-
-
-
270 (103), 363 (3), 382 (7), 407 (12), 431 (28), 460
(39)
271 (106), 286 (53), 363 (2), 382 (7), 407 (11), 431
(27), 460 (39)
270 (106), 286 sh (56), 363 (5), 382 (9), 407 (14), 431
(31), 460 (44)
271 (104), 289 sh (53), 311 (46), 363 (7), 382 (10),
407 (15), 431 (33), 460 (46)
530,
575sh
465, 495, 530
87
4.2
541
4
3.8
5.5
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
14
15
465, 495, 530
465, 495, 530
93
2
4.4
4.2
535
541
516, 555
525, 562
5
1
11.8
16
465, 495, 530
465, 495, 530
1
4.0
4.7
-
-
-
-
-
-
16H+c
271 (105), 384 (9), 408 (12), 433 (26), 461 (36)
39
a λex = 430 nm; b λex = 350 nm; c 16 in the presence of 0.1 M CF3COOH in CH2Cl2.
The positions of the emission maxima are very similar within in the range of 1–7% (Table 2). All complexes of these groups
each group of complexes and the spectra are only different in both at room temperature and at 77 K display structured LE
relative intensities of HE fluorescence and LE phosphorescence bands with line shapes, which resemble the profiles of the
bands (Figure 6). The invariance of the emission energies and phosphorescence profiles revealed in solution (Fig. S6). The
thus of the lowest lying excited states (S1 and T1) is in line with long lifetimes (2.1–86.3 μs for 5–8 and 206–1694 μs for 9–12)
poor involvement of the alkynyl ligands in their composition. imply that only triplet emission retains in solid.
However, as we have shown earlier, the ancillary –C2R groups Complexes 13–16, 17–19 and 20–22. It has been shown earlier
are capable to affect the rate of intersystem crossing S1→Tn (n that gold complexes constructed of the diphosphines with
≥ 1), altering the contribution of MLCT/L´LCT transitions 13 The diethynyl-phenylene spacers, Ph2P–C2–(C6H4)n–C2–PPh2, often
non-innocent role of alkynyl ligands in populating the T1 state exhibit higher quantum efficiencies than their counterparts
is also seen for 5–8 and 9–12 (see the excitation spectra in Fig. composed of the ligands with phenylene backbones Ph2P–
S5), in which phenylakynyl complexes 5 and 9 show the largest (C6H4)n–PPh2.6a,
phosphorescence vs. fluorescence ratio within each series.
Therefore, low emission intensities of
compounds 1–12, which contain PPh2-functionalized PAH
24
It is worth comparing the photophysical performance of 5–12 moieties, prompted us to investigate photophysical
with that of the structurally related complexes of isomeric 1,8- characteristics of congener complexes 13–22 bearing ethynyl-
bis(diphenylphosphino)naphthalene studied by Yam.20 In the modified ligands L4–L6. Simultaneously, within these series we
latter case, the close disposition of the phosphorus have systematically altered the electronic properties of
substituents on the naphthalene backbone results in a virtually auxiliary phenylacetylene groups –C2C6H4–X (X = CF3, H, OMe,
complete suppression of the singlet emission in solution to NMe2) to inspect their influence on the optical behavior of
give phosphorescence in a red region (λem > 700 nm) and intra-phosphine PAH chromophores.
microsecond lifetimes. These emission characteristics Complexes (AuC2C6H4X)2L4 (X = H, 13; CF3, 14; OMe, 15; NMe2,
drastically differ from those of 5–12 and illustrate the effect of 16) with diethynyl-anthracene phosphine show absorptions
substitutional isomerism of the diphosphines (i.e. 1,4- spectra, which are mainly derived from that of the free ligand
naphthalene (L2), 2,6-naphthalene (L3) and 1,8-naphthalene20)
in the modulation of the lowest lying excited state.
In solid state, luminescence efficiency of 5–8 and 9–12 series is
enhanced compared to that in solution, the quantum yields fall
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Figure 8. Room temperature UV-vis absorption (dotted lines) and normalized emission (solid lines) spectra of 17–19 (A) and 20–22 (B) in degassed CH2Cl2; (C) normalized solid-
View Article Online
state emission spectra of 17–19 under an Ar atmosphere, color-filled profile corresponds to the spectra of 18 on air.
DOI: 10.1039/C9NJ03426A
5
6
7
Table 4. Photophysical properties of complexes 17–22.
Solution (CH2Cl2, 298 K)
Solid
Φemb, %
λema, nm
298 K
8
9
λabs, nm (ε×10-3, cm-1 M-1)
λema, nm
Φem, %
τobs, ns
λema, nm 77 K
τfc, ns
τph(av)d, μs
250 (39), 327 (14), 348 (25), 368
(28)
253 (65), 268 (60), 281 (57), 332
(28), 348 (47), 367 (55)
254 (47), 273 (52), 286 (51), 333
(21), 348 (34), 367 (41)
253 (48), 272sh (41), 284 (44),
332 (23), 348 (36), 367 (41)
267 (39), 328 (23), 342 (25)
261 (90), 271 (123), 284sh (55),
296 (39), 310 (48), 316 (51), 324
(67), 331 (69), 338 (37), 357 (8)
262 (87), 272 (121), 286 (69), 310
(44), 316 (49), 324 (64), 331 (66),
338 (37), 357 (8)
262 (74), 272 (101), 286 (50), 298
(50), 305 (52), 310 (54), 316 (52),
324 (61), 331 (60), 338 (37), 357
(8)
-
-
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
L5
17
18
-
-
8
-
-
432, 622,
680
414, 601,
658, 723
414, 603,
660, 727
454, 472 sh,
628, 689, 758
414, 438, 614,
666, 733
414, 438, 602,
620, 664, 730
377, 397
377, 397
380, 396
0.5
0.6
1.6
3
2
3
5.3
3.7
4.0
249.4
54.8
85.1
24
1
19
L6
550, 562, 600,
621, 650
20
21
361, 380, 400
361, 380, 400
4
1.1
1.2
400, 551
<1%
1
3.4
2.9
5.9
390, 542,
590, 647
385, 544, 556,
593, 644
11
91.6
410, 540,
590
536, 550, 587,
631
22
361, 380, 400
<1%
2.7
<1%
3.7
10.6
a λex = 330 nm; b total quantum yield measured on air at 298 K; c for HE fluorescence band at 298 K; d for LE phosphorescence band at 298 K, average emission lifetimes
for the two-exponential decay determined using the equation τav = (A1τ12 + A2τ22)/(A1τ1 + A2τ2), where Ai is the weight of the i-exponent.
L4 (Table 3 and Fig. 7). In addition to the absorption bands of C2C6H4NMe2 localized transitions. The latter evidently shifts to
the phosphine, complexes 13–16 display moderately intense higher energies due to stabilization of the alkynyl-aniline π
absorption shoulders in the range 286–311 nm, which can be orbitals caused by switching the electron-rich NMe2 function
attributed to C≡CR intraligand transitions. The emission to electron deficient NMe2H+ ammonium derivative.26
profiles for 13–16 are nearly the same irrespectively of the The solid-state emissions of complexes 13–15 are substantially
C≡CR ligand and also match the spectra of (PR3Au)2(9,10- red shifted (ca. 75 nm) with respect to their solution spectra
diethynylanthracene) complexes meaning that the PAH core of (Figure S7), 16 is not luminescent. Additionally, the loss of
The vibronic structure, dramatically lower intensity (Φem up to 5%
structured signals, high intensity (Φem = 87% and 93% for 13 for 14) and short emission lifetimes of several nanoseconds
L4 determines the luminescence properties.20,
25
1
and 14) and nanosecond lifetimes prove the IL (anthracene) evidence fluorescence, probably arising from intermolecular
nature of the excited state. The excitation spectra of 13–16 charge transfer between the PAH chromophores, which tend
(Fig. 7B) are essentially alike to the absorption spectrum of L4, to aggregate in the solid state.
meaning that LL´ (π C2R → π* L4)/ML (Au dπ → π* L4) charge The photophysical data for the series 17–19 and 20–22 with
transfers play a minor role for the lowest lying excited state S1. 1,4- and 2,6-diethynylnaphthalene emitting centers,
Despite the modulation of electron donating ability of – respectively, are listed in Table 4. In solution both groups of
C2C6H4X alkynyl ligands does not change the shape 14 (X = CF3) complexes reveal singlet emission HE signals in deep blue to
is the most intense fluorophore among the studied violet region with maximum quantum yields reached by CF3-
compounds (Φem = 93%), gradual increasing the basicity of X substituted alkynyl species 18 (Φem = 24%) and 21 (Φem = 11%).
substituents leads to a drastic drop of the quantum yield for 16 Analogously to the anthracene-based family 13–16 described
(X = NMe2, Φem = 1%). A similar trend was observed for Au(I) above, the naphthalene compounds 17–22 manifest a steep
complexes with oligophenylene π-chromophores, for which, dependence of fluorescence intensity on the electron richness
however, changing X = CF3 for OMe primarily enhances of the alkynyl ligands, which do not affect the energies of the
phosphorescence vs fluorescence emission.13 To gain bands (Figure 8).
additional experimental proof that alkynyl ligands can govern In the solid state, complexes 17–22 behave differently than in
the radiationless decay pathways, the photophysics of complex solution and display two emission bands, which are
16 has been studied in the presence of trifluoroacetic acid. particularly pronounced for CF3-containing compounds 18 and
Indeed, protonation of the NMe2 group results in ca. 35-fold 21 (Figures 8C and S8, S9). The broadened unresolved HE
increase of luminescence intensity (Table 3 and Figure 7C) and signals, which have the lifetimes of few nanoseconds, are red
disappearance of ~300 nm absorption band assigned to shifted for ca. 30 nm with respect to the corresponding
10 | J. Name., 2012, 00, 1-3
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fluorescence bands in solution. The intensity of long-lived LE → X = NMe2, , Φem = 1%) complexes 13–16. The reVpielawcAertmicleeOnntlionef
emissions (λem > 600 nm for 17–19 and > 540 for 20–22) is the anthracene motif for the naphthDaOleIn: 1e0.1c0o3r9e/C9pNrJo0d3u42c6eAs
readily reduced on air, the extent of quenching is supposedly distinct dual emission in solution for L2 and L3-based
dependent on the morphology of the solid sample and is complexes 5–12. Their luminescence profiles comprise the
facilitate by its intrinsic porosity.13 Notably, the Commission high-energy fluorescence band centered at ca. 350 nm and
Internationale de l’Eclairage (CIE) coordinates of the vibronically structured phosphorescence signal with the
compound 21 in the solid state (Table S3) correspond to nearly wavelength maxima above 500 nm. In the solid state, the
pure white color (0.32, 0.32). The fluorescence vs fluorescence signals for these species are completely
phosphorescence ratio for 17–19 at 298 K can be correlated suppressed and only triplet emission is observed. In contrast to
with donicity of alkynyl ligands, the increase of which favors 5–12, their ethynyl-phosphine congeners 17–22 (L4 and L5-
transition to the T1 state, and therefore explained in terms of based compounds) in solution exhibit only structured HE
variable MLCT/L´LCT contributions.13 However, the triad 20–22 fluorescence, as manifested by nanosecond lifetimes of the
does not obey the given trend (Figure S9) that testifies to the excited state, with maximum quantum yields attained for 18
presence of subtle effects, which operate in solid phase and (Φem = 24%) and 21 (Φem = 11%) with CF3-substituted alkynyl
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
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32
33
34
35
36
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40
41
42
43
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47
48
49
50
51
52
53
54
55
56
57
58
59
60
have fine influence on the optical characteristics.
groups. However, as solid powders complexes 17–22 are
It is pertinent to remark the discrepancy in emission behavior dually luminescent at room temperature. This effect is
for 17, 20 and of their aryl relatives 5 and 9 bearing same tentatively ascribed to the influence of ethynyl fragments
phenyl alkynyl ligands. The latter complexes are dually between the phosphorus atoms and the π-spacers, which
emissive in solution, but in the solid state demonstrate pure increase the PAH…Au distance and consequently diminishes
phosphorescence. In a simplified approach, the difference in spin-orbit coupling, resulting in radiative relaxation of both S1
inducing triplet luminescence in 17, 20 vs 5, 9 stems from the and T1 states only in the solid state.
nature of coordinating group, which links the chromophore
PAH center to the gold ion and therefore determines the
electronic communication and the distance between them.
The smaller separation PAH…Au in 5, 9 presumably facilitates
Conflicts of interest
There are no conflicts to declare.
spin-orbit coupling primarily via heavy atom effect and rises
the rate of intersystem crossing S1→Tn so that
phosphorescence starts to compete with fluorescence in fluid
Acknowledgements
medium and prevails in solid samples. In line with this
Financial support from the Academy of Finland (grant 317903,
rationalization, the direct bonding of naphthalene to {AuPR3}
I.O.K.) and Russian Science Foundation (spectral
fragments almost completely suppresses singlet emission
characterization and photophysical studies, grant 19-13-00132,
already in solution.4c In the case of 17–22 the additional
S.P.T.) is gratefully acknowledged. The work was performed
ethynyl spacers of the diphosphine backbones increase both
using the equipment of the Analytical Centre for Nano- and
the PAH…Au gap and fluorescence quantum efficiency, but
Biotechnologies (Peter the Great St Petersburg Polytechnic
prevent triplet emission in solution due to poor ISC. On the
University with financial support from the Ministry of
other hand, for these compounds dual luminescence is
Education and Science of Russian Federation); Centers for
attained in the solid state that provides a route to molecular
Magnetic Resonance, for Optical and Laser Materials Research,
materials for panchromatic light generation.
for Chemical Analysis and Materials Research, Research Park of
St. Petersburg State University.
Conclusions
In this work, we have synthesized a series of luminescent
dinuclear gold(I) alkynyl complexes constructed of phosphine-
References
1. (a) C. Reichardt, Chem. Rev., 1994, 94, 2319-2358; (b) N. Siraj, B.
functionalized polyaromatic (PAH) chromophores. Systematic
alteration of PAH moieties, the position and electronic
features of P-donor connectivities reveal an essential influence
on the optical behavior of the metal compounds. The
anthracene-based gold(I) complexes 1–4 and 13–16 apparently
demonstrate intraligand fluorescence localized on the
diphosphine backbone with negligible contribution of the
alkynyl and metal d orbitals into the emissive excited state. An
El-Zahab, S. Hamdan, T. E. Karam, L. H. Haber, M. Li, S. O.
Fakayode, S. Das, B. Valle, R. M. Strongin, G. Patonay, H. O.
Sintim, G. A. Baker, A. Powe, M. Lowry, J. O. Karolin, C. D.
Geddes, I. M. Warner, Analytical Chemistry, 2016, 88, 170-202.
2. (a) X.-K. Chen, D. Kim, J.-L. Brédas, Acc. Chem. Res., 2018, 51,
2215-2224; (b) S.-C. Lee, J. Heo, H. C. Woo, J.-A. Lee, Y. H. Seo,
C.-L. Lee, S. Kim, O. P. Kwon, Chem. Eur. J., 2018, 24, 13706-
13718; (c) L. Wang, M. S. Frei, A. Salim, K. Johnsson, J. Am.
Chem. Soc., 2019, 141, 2770-2781.
3. (a) Y. Y. Chia, M. G. Tay, Dalton Trans., 2014, 43, 13159–13168;
(b) H. Xu, R. Chen, Q. Sun, W. Lai, Q. Su, W. Huang, X. Liu, Chem.
Soc. Rev., 2014, 43, 3259-3302; (c) F. N. Castellano, Acc. Chem.
Res., 2015, 48, 828−839; (d) V. W.-W. Yam, V. K.-M. Au, S. Y.-L.
Leung, Chem. Rev., 2015, 115, 7589–7728.
extension
of
the
PAH
spacer
(anthracene
→
diethynylanthracene) appears to be an efficient tool for
increasing quantum yield in solution; compounds 1–4 show
Φem up to 5%, whereas for 13–16 Φem reaches 93%. Increasing
the basicity of substituents X in alkynyl ligands –C2C6H4X leads
to a drastic drop of the emission intensity (X = CF3, Φem = 93%
4. (a) J. H. K. Yip, J. Prabhavathy, Angew. Chem. Int. Ed., 2001, 40,
2159-2162; (b) V. W.-W. Yam, K.-L. Cheung, S.-K. Yip, N. Zhu,
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Photochem. Photobiol. Sci., 2005, 4, 149-153; (c) L. Gao, M. A. 15. Y.-P. Ou, C. Jiang, D. Wu, J. Xia, J. Yin, S. Jin, G.-AV.ieYwuA, rStic.leHO. nLliinue,
Peay, D. V. Partyka, J. B. Updegraff, T. S. Teets, A. J. Esswein, M. Organometallics, 2010, 30, 5763–5770.
Zeller, A. D. Hunter, T. G. Gray, Organometallics, 2009, 28, 16. J. N. Demas, G. A. Crosby, J. Phys. Chem., 1971, 75, 991-1024.
5669–5681; (d) M.-H. Nguyen, J. H. K. Yip, Organometallics, 17. (a) V. W.-W. Yam, S. W.-K. Choi, K.-K. Cheung, Organometallics,
DOI: 10.1039/C9NJ03426A
2010, 29, 2422–2429; (e) L. Gao, D. S. Niedzwiecki, N. Deligonul,
M. Zeller, A. D. Hunter, T. G. Gray, Chem. Eur. J., 2012, 18, 6316-
6327; (f) S. Goswami, R. W. Winkel, K. S. Schanze, Inorg. Chem.,
1996, 15, 1734-1739; (b) M. Ferrer, A. Gutiérrez, L. Rodríguez,
O. Rossell, J. C. Lima, M. Font-Bardia, X. Solans, Eur. J. Inorg.
Chem, 2008, 2899–2909.
2015, 54, 10007−10014; (g) A. M. Christianson, F. P. Gabbaï, 18. (a) E. R. T. Tiekink, J.-G. Kang, Coord. Chem. Rev., 2009, 253,
Inorg. Chem., 2016, 55, 5828−5835; (h) J. R. Shakirova, O. A.
Tomashenko, E. V. Grachova, G. L. Starova, V. V. Sizov, A. F.
Khlebnikov, S. P. Tunik, Eur. J. Inorg. Chem., 2017, 2017, 4180- 19. (a) K. Zhang, J. Prabhavathy, J. H. K. Yip, L. L. Koh, G. K. Tan, J. J.
1627–1648; (b) H. Schmidbaur, A. Schier, Chem. Soc. Rev., 2012,
41, 370-412.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
4186; (i) A. Gutiérrez-Blanco, V. Fernández-Moreira, M. C.
Gimeno, E. Peris, M. Poyatos, Organometallics, 2018, 37, 1795-
1800.
Vittal, J. Am. Chem. Soc., 2003, 125, 8452-8453; (b) R. Lin, J. H.
K. Yip, K. Zhang, L. L. Koh, K.-Y. Wong, H. K. Piu, J. Am. Chem.
Soc., 2004, 126, 15852-15869.
5. (a) J. C. Lima, L. Rodriguez, Chem. Soc. Rev., 2011, 40, 5442– 20. V. W.-W. Yam, S. W.-K. Choi, J. Chem. Soc., Dalton Trans., 1996,
5456; (b) Y. Liu, H. Guo, J. Zhao, Chem. Commun., 2011, 47, 4227-4232.
11471–11473; (c) T. Yoshihara, Y. Yamaguchi, M. Hosaka, T. 21. J. Li, X.-F. Zhu, L.-Y. Zhang, Z.-N. Chen, RSC Adv., 2015, 5, 34992-
Takeuchi, S. Tobita, Angew. Chem. Int. Ed., 2012, 51, 4148-4151; 34998.
(d) T. Yoshihara, Y. Yamaguchi, M. Hosaka, T. Takeuchi, S. 22. (a) Z. Fei, N. Kocher, C. J. Mohrschladt, H. Ihmels, D. Stalke,
Tobita, Angew. Chem. Int. Ed., 2012, 51, 4148–4151; (e) P. W.
Zach, S. A. Freunberger, I. Klimant, S. M. Borisov, ACS Appl.
Mater. Interfaces, 2017, 9, 38008-38023.
Angew. Chem. Int. Ed., 2003, 42, 783-787; (b) Y. Zhao, L. Duan,
X. Zhang, D. Zhang, J. Qiao, G. Dong, L. Wang, Y. Qiu, RSC Adv.,
2013, 3, 21453-21460.
6. (a) Y.-C. Chang, K.-C. Tang, H.-A. Pan, S.-H. Liu, I. O. Koshevoy, A. 23. L. Gao, D. V. Partyka, J. B. I. Updegraff, N. Deligonul, T. G. Gray,
J. Karttunen, W.-Y. Hung, M.-H. Cheng, P.-T. Chou, J. Phys. Eur. J. Inorg. Chem, 2009, 2711–2719.
Chem. C, 2013, 117, 9623–9632; (b) M. Bachmann, O. Blacque, 24. V. F. Moreira, J. Cámara, E. S. Smirnova, I. O. Koshevoy, A.
K. Venkatesan, Chem. Eur. J., 2017, 23, 9451–9456; (c) M. Pan,
W.-M. Liao, S.-Y. Yin, S.-S. Sun, C.-Y. Su, Chem. Rev., 2018, 118,
8889-8935.
Laguna, S. P. Tunik, M. C. Blanco, M. C. Gimeno,
Organometallics, 2016, 35, 1141−1150.
25. V. Mishra, A. Raghuvanshi, A. K. Saini, S. M. Mobin, J.
Organomet. Chem., 2016, 813, 103-109.
7. (a) H. Shi, H. Sun, H. Yang, S. Liu, G. Jenkins, W. Feng, F. Li, Q.
Zhao, B. Liu, W. Huang, Adv. Funct. Mater., 2013, 23, 3268- 26. I. O. Koshevoy, A. J. Karttunen, S. P. Tunik, J. Jänis, M. Haukka,
3276; (b) Q. Zhao, X. Zhou, T. Cao, K. Y. Zhang, L. Yang, S. Liu, H.
Liang, H. Yang, F. Li, W. Huang, Chem. Sci., 2015, 6, 1825–1831;
(c) F. Liu, J. Wen, S.-S. Chen, S. Sun, Chem. Commun., 2018, 54,
1371-1374.
A. S. Melnikov, P. Y. Serdobintsev, T. A. Pakkanen, Dalton Trans.,
2010, 39, 2676–2683.
8. H. G. Raubenheimer, H. Schmidbaur, Organometallics, 2012, 31,
2507-2522.
9. (a) W. Y. Heng, J. Hu, J. H. K. Yip, Organometallics, 2007, 26,
6760–6768; (b) D. V. Partyka, T. S. Teets, M. Zeller, J. B.
Updegraff, A. D. Hunter, T. G. Gray, Chem. Eur. J., 2012, 18,
2100–2112.
10. (a) W. Lu, W.-M. Kwok, C. Ma, C. T.-L. Chan, M.-X. Zhu, C.-M.
Che, J. Am. Chem. Soc., 2011, 133, 14120–14135; (b) J. Gil-
Rubio, V. Cámara, D. Bautista, J. Vicente, Organometallics, 2012,
31, 5414-5426; (c) K. T. Chan, G. S. M. Tong, W.-P. To, C. Yang, L.
Du, D. L. Phillips, C.-M. Che, Chem. Sci., 2017, 8, 2352–2364; (d)
M. Ferrer, L. Giménez, A. Gutiérrez, J. C. Lima, M. Martínez, L.
Rodríguez, A. Martín, R. Puttreddy, K. Rissanen, Dalton Trans.,
2017, 46, 13920-13934; (e) E. Aguiló, A. J. Moro, M. Outis, J.
Pina, D. Sarmento, J. S. Seixas de Melo, L. Rodríguez, J. C. Lima,
Inorg. Chem., 2018, 57, 13423-13430; (f) S. Wan, W. Lu, Angew.
Chem. Int. Ed., 2017, 56, 1784-1788; (g) E. C. Constable, C. E.
Housecroft, M. K. Kocik, M. Neuburger, S. Schaffner, J. A.
Zampese, Eur. J. Inorg. Chem., 2009, 2009, 4710-4717; (h) X.-L.
Li, K.-J. Zhang, J.-J. Li, X.-X. Cheng, Z.-N. Chen, Eur. J. Inorg.
Chem., 2010, 2010, 3449-3457.
11. (a) T. L. Stott, M. O. Wolf, B. O. Patrick, Inorg. Chem., 2005, 44,
620-627; (b) Z. Chen, G. Liu, R. Wang, S. Pu, RSC Adv., 2017, 7,
15112-15115.
12. I. O. Koshevoy, C.-L. Lin, C.-C. Hsieh, A. J. Karttunen, M. Haukka,
T. A. Pakkanen, P.-T. Chou, Dalton Trans., 2012, 41, 937-945.
13. I. Kondrasenko, K.-y. Chung, Y.-T. Chen, J. Koivistoinen, E. V.
Grachova, A. J. Karttunen, P.-T. Chou, Igor O. Koshevoy, J. Phys.
Chem. C, 2016, 120, 12196−12206.
14. (a) G. E. Coates, C. Parkin, J. Chem. Soc., 1962, 3220-3226; (b) I.
O. Koshevoy, Y.-C. Chang, A. J. Karttunen, S. I. Selivanov, J. Jänis,
M. Haukka, T. A. Pakkanen, S. P. Tunik, P.-T. Chou, Inorg. Chem.,
2012, 51, 7392−7403.
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