Luminescence Thermochromism of Gold(I) Phosphane–Iodide Complexes: A Rule or an Exception?

Article abstract of DOI:10.1002/chem.201705544

A series of gold(I) iodide complexes 1–11 have been prepared from di-, tri-, and tetraphosphane ligands. Crystallographic studies reveal that the di- (1–7) and tetrametallic (11) compounds feature linearly coordinated gold(I) ions with short aurophilic contacts. Their luminescence behavior is determined by the combined influence of the phosphane properties, metal–metal interaction, and intermolecular lattice-defined interactions. The proposed variable contribution of ³(X+M)-centered (X=halogen; M=metal) and ³XLCT (halogen to ligand charge transfer) electronic transitions into the lowest lying excited state, which is influenced by supramolecular packing, is presumably responsible for the alteration of room-temperature emission color from green (λ=545 nm, for 11) to near-IR (λ=698 nm, for 2). Dinuclear compounds 6 and 7 exhibit distinct luminescence thermochromism with a blueshift up to 5750 cm^?1 upon cooling. Such dramatic change of emission energy is assigned to the presence of two coupled triplet excited states of ³ππ* and ³(X+M)C/³XLCT nature, the presence of which depends on both molecular structure and the crystal lattice arrangement.

Full text of DOI:10.1002/chem.201705544

A Journal of
Accepted Article
Title: Luminescence thermochromism of gold(I) phosphane-iodide
complexes: a rule or an exception?
Authors: Igor O. Koshevoy, Nina Glebko, Thuy Minh Dau, Alexei S.
Melnikov, Elena V. Grachova, Igor V. Solovyev, Andrey
Belyaev, and Antti J. Karttunen
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Luminescence thermochromism of gold(I) phosphane-iodide
complexes: a rule or an exception?
Nina Glebko,[a] Thuy Minh Dau,[a] Alexei S. Melnikov,[b] Elena V. Grachova,[c] Igor V. Solovyev,[c] Andrey
Belyaev,[a,c] Antti J. Karttunen*[d] and Igor O. Koshevoy*[a]
Abstract: The series of gold(I) iodide complexes 1–11 have been
prepared using di-, tri- and tetraphosphane ligands. Crystallographic
studies reveal that the di- (1–7) and tetrametallic (11) compounds
feature linearly coordinated Au(I) ions with short aurophilic contacts.
Their luminescence behavior is determined by the joint influence of
the phosphane properties, metal–metal and the intermolecular
lattice-defined interactions. The proposed variable contribution of
3(X+M)-centered and 3XLCT electronic transitions into the lowest
lying excited state influenced by the supramolecular packing, is
presumably responsible for the alteration of room temperature
emission color from green (545 nm, 11) to near-IR (698 nm, 2).
charge transfer (metal to ligand, ligand to metal, ligand to ligand)
and metal/cluster-centered (CC) origin. The population of such
energetically different excited states is governed by
intramolecular reorganization (e.g. by means of non-covalent
contacts)[3] or weak intermolecular interactions (mostly defined
by crystal lattice in the solid state),[4] thermally dependent
modulation of which is responsible for the emergence of
controllable panchromatic luminescence.
In this respect, cluster complexes of copper subgroup metals,
are capable of displaying thermochromic emission for the cases
of properly selected ligand environment that normally contains
halide ions. Noteworthy, these compounds often feature short
metal–metal contacts, which are typically considered as
metallophilic bonding based on the results of structural analysis.
The tetranuclear cubane species [Cu4I4L4] (L = phosphane,
pyridine) represent the most well studied family of temperature-
responsive d10 dual luminophores.[5] These iodide compounds
exhibit intense low energy emission (green-yellow) under the
ambient conditions, assigned to the triplet cluster-centered
excited state (CC), while at 77 K the domination of high energy
band (deep-blue emission) is attributed to charge transfer
character (metal to ligand and halogen to ligand, MLCT/XLCT)
of the excited state, which is unable to undergo transition to the
3CC one because of the lack of vibration energy.[5c] A similar
behavior has been recently reported for [Cu4I4(PN)2] compound
Dinuclear compounds
6 and 7 exhibit distinct luminescence
thermochromism with up to 5750 cm-1 blue shift upon cooling. Such
dramatic change of emission energy is assigned to the presence of
two coupled triplet excited states of 3ʌʌ* and 3(X+M)C/3XLCT nature,
the presence of which depends on both molecular structure and the
crystal lattice arrangement.
Introduction
Photoemissive compounds and materials, which demonstrate a
detectable response of physical parameters (wavelength,
intensity, lifetime) to the temperature changes (i.e. luminescent
thermometers), play an essential role in optical monitoring of
thermal variations, performed for the different temperature
ranges, surrounding media, scales of the measured objects and
local environment.[1] Thermally induced switching of the
luminescence color due to (i) the large shift of emission
maximum, or, particularly, (ii) the presence of two distinct and
variable emission bands, remains a more rare optical behavior
than rather common relationships between the lifetime or
intensity and the temperature.[2]
(PN
=
phospholan-pyridine) with square planar metal
arrangement.[6] Alternatively, the 2D metal-organic framework,
built of Cu6I6 clusters and tridentate N-donor ligands, shows a
substantial hypsochromic shift of phosphorescence (4554 cm-1,
from 611 nm at 298 K to 478 nm at 77 K) presumably without
changing the origin of the emission (MLCT/XLCT), but due to
crystal packing-induced destabilization of the LUMO.[7]
Furthermore, the decoration of {Cu2I2} core with two Cu6L3 motifs
(L = pyrazolyl pyridine derivative) produced dually emissive
complex with variable relative intensities of low and high energy
bands in a wide range of temperatures.[8]
Thermally regulated dual emission has been successfully
achieved for a number of transition metal complexes containing
two or more interacting metal ions. These compounds potentially
can have several accessible excited states of intraligand (IL),
Conversely, silver polynuclear compounds with thermally
variable dual luminescence are very scarce. The reported
examples encompass Ag31/Ag33 thiolate clusters with up to 2856
cm-1 bathochromic shift of emission upon cooling from 298 to 77
K,[9] and cubane iodide complex [Ag4I4(phosphane)4], which
demonstrates contrary temperature dependent behaviour for
crystalline and powdered samples.[10]
[a]
N. Glebko, T. M. Dau, A. Belyaev, Prof. I.O. Koshevoy
Department of Chemistry, University of Eastern Finland,
Yliopistokatu 7, Joensuu, Finland
E-mail: igor.koshevoy@uef.fi
[b]
[c]
[c]
Dr A. S. Melnikov
Gold(I) ions have higher oxidation potential compared to copper
and silver metals and therefore are less prone to participate in
MLCT transitions. Thus, the rare cases of Au(I) thermally
responsive emitters primarily imply ʌʌ* intraligand (IL), metal-
centered and LM(M)CT excited states, which might result in the
appearance of two or more emission bands.[11] A remarkable
luminescence thermochromism has been reported for
Peter the Great St.-Petersburg Polytechnic University
Polytechnicheskaya, 29, St.-Petersburg, Russia
I. V. Solovyev, Prof. E. V. Grachova
Institute of Chemistry, St.-Petersburg State University
26 Universitetskiy pr., Petergof, St.-Petersburg, Russia
Prof. A. J. Karttunen
Department of Chemistry and Materials Science,
Aalto University, FI-00076 Aalto, Finland
E-mail: antti.j.karttunen@aalto.fi
3
[Au3(pyrazolate)3] complex, whose emission of CC type (both at
77 K and 298 K) was proposed to be strongly affected by
Supporting information for this article is given via a link at the end of
the document.
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Scheme 1. The phosphane ligands and their gold(I) complexes 1–11, described in this work.
intermolecular spacing.[12] Similarly, single crystal phase change
that occurs upon cooling, was observed for the cationic sulfide
trinuclear cluster [S(AuCNR)3]+. This process generates two
series of iodide complexes using a selection of di-, tri- and
tetraphosphane ligands.
different types of intermolecular aggregates at 77
modulation of aurophilic contacts, and consequently causes two
phosphorescence signals maximized at 490 and 680 nm.[4a]
K via
Results and Discussion
A
very large emission thermochromism of 10164 cm-1, ascribed to
internal conversion between T2 and T1 excited states, has been
lately described for a trinuclear imidazolate Au(I) cluster.[13]
Essentially, this appealing photophysical behaviour could not be
correlated with changes of intra- or intermolecular metal–metal
distances or phase changes. The intramolecular switching of
luminescence origin upon changing the temperature has been
described only for few di- and triphosphane halide[14] and
cationic[15] gold(I) species, for which blue shifted IL
phosphorescence prevails at low temperature, while metal-
dominated LE emission with poor quantum yields (ĭem of ca. 1–
2%)[14a] was observed at 298 K.
Synthesis and structural characterization. The digold(I)
iodide phosphane complexes and the related species of higher
nuclearity generally can be obtained in a straightforward way by
reacting the stoichiometric amounts of AuI and the
corresponding ligand.[16] This simple approach was used to
prepare the bimetallic compounds [(AuI)2(diphosphane)] 1–3 and
7 (diphosphane = dppb, biphep, dpbp, tpdpO, respectively),
isolated as nearly colourless solids after conventional
recrystallization, see Scheme 1 and experimental section (ESI).
For the synthesis of the complexes with diphosphane-diphenyl
ether ligands (DPEphos, 4; N-XantPhos, 5 and XantPhos, 6) we
used a solvothermal method (acetonitrile, 200 oC, N2 40 atm),
which afforded crystalline materials suitable for XRD analysis,
though in visibly lower yields particularly for 5 and 6 (39 and
41%). Compounds 2,[17] 4[18] and 6[18] were obtained previously
utilizing different protocols; 4 and 6 were reported in different
crystalline modifications. Also, the optical properties of 2, 4, 6
were not investigated and therefore these species were included
in the current study.
A
limited understanding of the factors, which guide
thermochromic properties of Au(I)-based materials, prevents
rational design of these complexes on the molecular and
macroscopic levels. Nevertheless, it is important that the ligand
(phosphane) orbitals can significantly contribute into the
emissive states of gold luminophores. This fact points to a
potentially high tunability of their photophysical performance that
could make simple and easy to prepare phosphano-halide Au(I)
complexes a diverse alternative to copper thermally switchable
phosphors. To extend a so far limited class of temperature
responsive gold(I) species, herein we report on the preparation,
systematic structural and photophysical investigations of a
In the case of N-XantPhos and XantPhos ligands the
mononuclear complexes [AuI(diphosphane)] (8 and 9) are
obtained in substantially better yields than their dinuclear
congeners (Scheme 1). The easier formation of the
monometallic species could be a reason for the relatively
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Figure 1. Molecular views of complexes 1–3 (thermal ellipsoids are shown at 50% probability). Symmetry transformations used to generate equivalent atoms (´) in
1: 1–x, y, 0.5–z.
ineffective synthesis of the digold compounds 5 and 6 even if
correct stoichiometry is obeyed. This preference of chelating vs
bridging coordination mode probably arises from the rigidity of
the ligands’ xanthene backbone and the appearance of the
unfavourable strain while binding to the Au2 motif.
appearing upon bridging the digold moieties. Thus, the smallest
torsion angle P–Cipso1– Cipso2–P (< 4.6 , Table S2) is observed
for complexes 1 and 11 as a result of the suitable bite angle and
the ligand rigidity, while the diphosphanes with bendable
spacers attain the optimal geometries through the formation of
highly twisted configurations. The structural peculiarities of the
o
To extend the series, the triphosphane tpdp was employed to
produce a four-coordinate complex [AuI(tpdp)] (8). Unfortunately, chloroform solvate of 4 and of the bromide analogue of 6 have
the attempts to prepare
a
trinuclear iodide analogue of
been discussed in detail by Gray.[18]
[(AuCl)3(tpdp)][19] were unsuccessful and gave 10 along with
unidentified dark side product. The reaction of the tetradentate
ligand tppb with 4 equivalents of AuI leads to an insoluble
precipitate. To prove its composition, the crystalline form of
Molecular arrangements of 1 and 2 are essentially similar to
those of the chloride congener [(AuCl)2(dppb)][23] and of closely
related complexes with biphep-like ligands ([(AuI)2(2,2´-
Et2PC6H4C6H4PEt2)][17] and [(AuI)2(Me-biphep)][24]), respectively.
Compound 3 has the longest gold–gold distance that might be a
result of a weak Au–O interaction. One such contact in 3 equals
[(AuI)4(tppb)] (11) was obtained following
protocol, applied for the synthesis of 4–8 (ESI).
a solvothermal
The solid state structures of all the title compounds were
determined by single crystal XRD analysis (Figures 1–3 and S1;
crystal data is given in Table S1, Supporting Information). The
digold complexes 1–7 and the tetranuclear relative 11
demonstrate the Au–Au contacts, which fall in the range from
2.9767 to 3.3156 Å (Table S2). These values are below the sum
of two van der Waals radii for gold (3.32 Å) and are typical for
gold–gold separations, associated with aurophilic bonding.[20]
However, it should be pointed out that short distances do not
unambiguously prove the presence of a bond between the metal
centers because they can be caused by the ligand environment
and packing effects. As a result of possible metal-metal
attraction, the P–Au–I angles in these species visibly deviate
from linearity and approach the value of 162.25 o (6), while in the
absence of Au–Au contacts (4.C6H6) these angles are 178.17o
and 178.67o. However, bending of the P–Au–I motif can arise
from other than aurophilic non-covalent interactions, which are
induced by the crystal packing. This can be illustrated e.g. by the
complex [(AuI)2(BINAP)][21] with the corresponding angle of
172.20o attained without short Au–Au separations. Except 1, the
gold ions in 2–7 and 11 are structurally inequivalent and adopt
slightly different coordination geometries. The general feature of
1–7 and 11 is the twisting of the {PAuI}2 motifs (I–Au–Au–I
3.148 Å
(Table S2) and represents the shortest Au…O
separation found among the dinuclear complexes 3–7 with
oxygen-containing phosphanes, indicating a possible donation of
some electron density to the metal center that possibly affects
the Au–Au separation.
Complex 4 crystallizes in several forms depending on the
solvent used; the resulting materials show different optical
behavior (see the photophysical studies below). The
crystallographic parameters of the dichloromethane solvate
4.CH2Cl2 (spacegroup, unit cell dimensions, see Table S1) are
virtually identical to those of 4.CHCl3.[18] Expectedly, the
corresponding structural characteristics of 4.CH2Cl2 and 4.CHCl3
have nearly the same values. On the contrary, the modification
of 4.C6H6 obtained from benzene shows no aurophilic interaction
(Figure S1), the absence of which is presumably compensated
in energy by rather extensive inter- and intramolecular ʌꢀʌ
interactions compared with 4.CH2Cl2. Using a solvothermal
method, a solvent-free modification 4 was isolated from its
acetonitrile solution. The molecular conformation of 4 closely
resembles that of 4.CH2Cl2 though has a noticeably longer Au–
Au distance (3.0682 Å) than the dichloromethane solvate
(2.9459 Å). Noteworthy, according to the calculated density of
the crystals, 4 adopts the most compact packing with respect to
its solvated forms. This may be attributed to the combination of
intermolecular ʌ-stacking and I…H hydrogen bonding that results
in a more rigid lattice of 4 (Figure S1) and determines its distinct
photophysical performance (vide infra).
o
torsion angles are 56.7–92.8 ) that apparently reflects the trend
to decrease dipole-dipole interactions (i.e. the repulsion between
the iodine p-orbitals), which are minimized in the perpendicular
22]
systems formed in the absence of steric strain.[18,
The
distortions of the phosphane scaffold are dictated by their
stereochemistry and flexibility, which tends to reduce the stain
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Figure 2. Molecular views of complexes 5, 7 and 11 (thermal ellipsoids are shown at 50% probability).
The molecular structures of 5 and 6 (Figures 2 and S2) are very
much alike; not surprisingly the latter is also akin to complexes
[(AuHal)2(XantPhos)] (Hal = Cl, Br).[18, 25] The main difference
can be seen in the distortion of the diphosphane’s backbone,
which is less pronounced in the case of 5 (PCCP torsion angle is
three signals of 1:1:1 relative intensity (Figure S4). This is
compatible with stereochemically different P nuclei of tpdpO
ligand meaning that the crystal structure of 7 is retained in fluid
medium at 298 K. Raising the temperature to 353 K increases
the rate of the dynamic processes and makes the terminal PPh2
groups equivalent in the NMR time scale. Complex 10 displays
an AB2 spin system in its 31P NMR spectrum that is in
accordance with the data for other tpdp-containing
compounds.[26c, 27]
Solid state photophysical properties. Soft iodide ligand has
been chosen for this series due to its reported ability to facilitate
the aurophilic bonding,[28] which often has a strong impact on the
photophysical behaviour of gold complexes. Additionally, it has
been noticed that the effect of temperature on the emission
energy is more prominent for the I-containing compounds.[14a]
None of the soluble complexes under study (1–4, 9 and 10)
shows appreciable luminescence in fluid medium, therefore the
investigation of the photophysical properties was carried out for
crystalline materials only, the corresponding data is listed in
Table 1. Among the dinuclear species 1–7 and their tetragold
congener 11, which demonstrate metal–metal contacts,
compounds 3 and 5 are barely emissive at room temperature
(Figure S5) with quantum yields being less than 10–3. Complex 3
features the broad band centered at ca. 650 nm, accompanied
o
o
17.5
vs 37.6
in 6) seemingly due to a somewhat larger
separation between phosphorus atoms in 5 (4.732 Å) compared
to 6 (4.657 Å).
The given structural analysis indicates that Au–Au dispersive
interactions are not likely to play the main role in producing the
molecular arrangements with metal–metal contacts. These
separations show a substantial deviation in length (2.9767 to
3.3156 Å) and are largely determined by the appropriate bite
angle of the bridging ligand along with favourable packing of the
discrete molecules in the crystal cell.
The mononuclear compounds 8–10 are not exceptional and
match the structures of their (pseudo)halide relatives.[26] Thus, in
the diphosphane complexes 8 and 9 the metal ions adopt
trigonal coordination geometry, while in the case of 8 the
triphosphane tpdp and the iodide ligands form a tetrahedral-like
environment around gold atom (Figure S3), where the Au–P
distances for the lateral P(1) and P(3) donors (2.3689 and
2.3361 Å) are visibly shorter than that involving the central
phosphorus atom (2.4621 Å, Table S3). The Au…O spacing in 8
and 9 exceed 3.14 Å that implies very weak interactions. Overall, by a shoulder at ca. 500 nm. The low energy band could be
the Au–P and Au–I contacts in 8–10 are systematically longer
than the corresponding values in 1–7 and 11, where the Au(I)
ions are two-coordinate.
tentatively associated with (M+X)-centered (X = iodide) excited
state of the triplet nature that is in line with earlier reports on the
14a, 22b]
gold phosphane-halide systems,[11a,
though a precise
Crystalline compounds 5, 6, 8 and 11 are virtually insoluble in
common organic solvents that prevented their characterization in
solution. The 31P NMR spectra of 1–4 and 9 show a singlet
resonance each that corresponds to the equivalence of the
phosphorus atoms; their coordination to the gold ions is
confirmed by the typical low field shifts of the signals with
respect to the parent ligands. In the case of 2–4 it indicates that
the molecules adopt higher symmetry than that found in the solid
state due to the fast intramolecular motion, which might involve
dissociation of the Au–Au bonds. The dinuclear complex 7,
however, demonstrates a substantially higher rigidity than 2–4
under the ambient conditions. Its 31P NMR pattern consists of
assignment of the nature of the electronic states in such
systems is still pending The high energy shoulder, considerably
enhanced at 77 K, presumably originates from the metal-
perturbed intraligand (phosphane) transitions. Similarly, weak
luminescence of 5 under ambient conditions (Ȝem = 472 nm, Wav
=
3
54 Ps) can be attributed mainly to the IL excited state that is
evidenced by a distinguishable vibrational structure of the
emission band (Ȟ = ca. 1330 cm-1). This behaviour of 5,
containing N-XantPhos ligand, contrasts with that of [Au2(N-
XantPhos)2]2+ series, for which the observed yellow-orange
phosphorescence (Ȝem = 583–623 nm, Wav = 0.3–2 Ps) was
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Table 1. Solid state photophysical properties of 1–7, 9–11 and (AuI)2(BINAP) (AB).
298 K
77 K
Ȝexc, nm
327
Ȝem,a nm
551
W, Ps
ĭem
kr, s-1 c
7.0×104
2.4×104
<37
knr, s-1 d
2.0×105
1.8×105
3.7×104
4.3×103
1.9×105
1.9×104
2.1×105
7.9×104
7.9×104
3.6×105
3.0×105
Ȝexc, nm
327
Ȝem,a nm
W, Ps
4.6
1
3.7
5.0
27b
226b
4.3
54b
3.4
5.8
9.1b
1.8
2.8
0.26
0.12
<10-3
0.02
0.19
<10-3
0.28
0.54
0.28
0.35
0.17
583
654
2
332
698
306
15b
3
311
~650, ~500sh
527
311
~670, ~490
35
AB
4
335
88.5
330
527
654
519
450
480
500
660
545
~4000b
7.2
336
637
4.4×104
<19
326
5
370
472
332, 363sh, 387sh
320
2400b
1200b
368.0
16b
6
328
562
8.2×104
9.3×104
3.1×104
1.9×105
6.1×104
7
320
663
320
9
341, 363
418
486
327, 361sh
418
10
11
640
30.1
5.6
332, 380
545
335, 385
aꢁȜexc = 351 nm; b average emission lifetime for the two-exponential decay determined by the equation IJav = (A1IJ12 + A2IJ22)/( A1IJ1 + A2IJ2),
Ai = weight of the i exponent; c kr values were estimated by ĭꢀIJav
.
d knr values were estimated by kr (1-ĭ)/IJav.
visibly differ from those deduced for other complexes studied
here, and suggest extremely slow radiative rate constants kr at
298 K (Table 1) with respect to non-radiative decays that
accounts for low intensity long-lived luminescence.
The influence of the temperature on the emission energies of 5
and (AuI)2(BINAP) is relatively minor (Figure S5); cooling the
samples to 77 K leads to the dramatic increase of the decay
times up to 2.4 and 4 ms that has been noticed previously for
some other gold species.[31] This effect can be tentatively
explained in terms of very inefficient spin-orbit coupling (SOC)
due to the same parentage (ʌʌ*) of the lowest lying S1 and T1
excited states.
Another group of complexes comprises moderately intense
luminophores 1, 2, 4 and 11, which exhibit room temperature
phosphorescence with quantum yields 0.12–0.26 and the
lifetimes in the range 2.8–5.0 ȝs that gives radiative lifetimes (IJr
= IJobs/ĭem) of 14.2–41.7 ȝs indicative of strong SOC. These
compounds display broad and featureless spectroscopic
patterns (Figure 3) suggesting a significant charge transfer
character of the excited states. Taking into account high
oxidation potential of the Au(I) ion, it is reasonable to
hypothesize a negligible contribution of MLCT (AuЍphosphane)
transitions into the emissive T1 states of these molecules. Thus,
the nature of the lowest triplet excited state can be presumably
described as a substantial charge re-distribution occurring within
the {Au2I2} motifs, i.e. (X+M)-centered transitions, mixed with XL
(iodideЍphosphane) charge transfer.
Figure 3. Normalized solid state excitation (dotted lines) and emission (solid
lines) spectra of complexes 1, 2, 4 and 11 at 298 K.
assigned to Au2-based transitions,[29] indicative that the
relaxation to the lower-lying metal-centered excited state in
complex 5 is blocked at room temperature.
For the sake of comparison, optical behaviour of the
[(AuI)2(BINAP)][21] complex without metallophilic interactions has
been evaluated. The structured emission profile (Ȟ = ca. 1250
cm-1) and the lifetime of 226 Ps at 298 K point to the 3ʌʌ*
excited state, most probably located on the binaphtyl motif. Such
long lived excited state is compatible with the data obtained for
other gold(I) compounds, bearing phosphane ligands with
extended ʌ-chromophore backbones.[30] The emission lifetimes
for 3 and 5 observed at 298 K (27 and 54 ȝs, respectively),
This conclusion correlates with earlier assignments made for
gold
phosphane-iodide
compounds.[14a]
Unfortunately
computational investigation of the triplet excited states was not
possible as the DFT-PBE0 method severely underestimated the
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triplet emission energies, resulting in a very poor agreement with
the experimental values. Because of this failure (i.e. inadequate
triplet state geometries and the electron distribution), theoretical
studies are not included in the discussion.
The luminescence colours for 1, 2, 4, 11 and 6, 7 (vide infra)
under ambient conditions span from green (545 nm, 11) to near-
IR (698 nm, 2) and do not reveal any systematic dependence on
the ground state Au…Au distances.This variation of the emission
energies might arise from different contributions of 3(X+M)-
centered and 3XLCT character into the lowest energy excited
state that is responsible for a hypsochromic shift of the emission,
observed for 1, 6 and 11.
It is worth noting, that the photophysical properties of the title
complexes should be correlated with molecular structure only
with
a certain care. As mentioned above, 4 has been
characterized in three different modifications, out of which only
the solvent-free form exhibits distinct emission. If in the case of
its benzene solvate, 4.C6H6, the lack of luminescence can be
attributed to the absence of Au…Au interaction, for 4.CH2Cl2 with
gold–gold separation of 2.9459 Å (cf. 3.0682 Å in 4) it is difficult
to find a plausible simple explanation relying on the structural
analysis of an isolated molecule in the ground state. It is known
that the aurophilic contacts cannot be quantitatively correlated
with emission wavelengths.[11a, 32] The examples of 4.CH2Cl2 and
5 indicate that the presence of short Au…Au distances is not the
only condition for the emergence of metal-centered
luminescence, which is evidently influenced by the array of intra-
and intermolecular non-covalent interactions; the latter involve
H…Hal hydrogen bonding and ʌ-stacking. The importance of the
crystal lattice on the photoinduced distortions in d10 metal
clusters has been clearly shown by the combined experimental
and computational studies.[33]
Upon cooling to 77 K complexes 1 and 4 demonstrate moderate
bathochromic shift of emission bands (996 and 408 cm-1,
respectively), while 11 shows no alteration at all (Figure S6).
The lifetimes for these complexes also undergo insignificant
increase at low temperature and together with nearly invariable
excitation spectra indicate that the nature of the emissive excited
states remains unchanged in 77–298 K window (Table 1).
Despite the emission of compound 2 at 77 K displays moderate
gain in energy (964 cm-1 blue shift), it probably arises from the
stabilization of the ground state but not the change of the excited
state, as indicated by 2559 cm-1 hypsochromic shift of the
excitation maximum and only a modest growth of the lifetime
(from 5 to 15 ȝs) that is typical for pure phosphorescence.[34]
The last set of complexes with short metal-metal distances
includes the bimetallic species 6 and 7, which clearly exhibit
temperature-switchable emission. At 298 K these compounds
demonstrate yellow (Ȝem = 562 nm, 6) or red phosphorescence
ꢂȜem = 663 nm, 7) with characteristic lifetimes of few ȝs; the
quantum efficiency reaches the magnitude of 0.54 for 7. The
latter shows the highest radiative rate constant (kr = 9.3×104 s-1)
among the di-/tetranuclear complexes studied here that testifies
to strong SOC operating in 7.
Figure 4. Normalized solid state excitation (dotted lines) and emission (solid
lines) spectra of complex 7 at 298 and 77 K; the inset shows VT emission
spectra in the range of 180–116 K.
Crystalline 6 and 7, when immersed in liquid nitrogen, reveal a
dramatic blue shift of emission, which amounts to 5750 cm-1 for
7. Warming the samples to room temperature completely
recovers the initial low energy (LE) luminescence (Figures 4 and
S7). The variable temperature emission spectra of 6 and 7
demonstrate a gradual decrease of LE bands accompanied by
the growth of high energy (HE) band at 450–480 nm upon
cooling. The lifetimes of the HE emissions at 77 K (IJ = 1200 and
368 ȝs for 6 and 7, respectively) are orders of magnitude longer
than those obtained at 298 K that manifests different excited
states operating at low temperature and at ambient conditions.
Somewhat distinguishable fine structure of the HE bands and
the lifetimes comparable to those of 5, (AuI)2BINAP and the
related Xantphos-containing dinuclear congeners[15] suggest the
triplet intraligand (phosphane) origin of luminescence at 77 K.
For both complexes 6 and 7 the isosbestic points are found in
their VT emission spectra that is typical for the presence of two
thermally equilibrated excited states.[5c] This conclusion is also
supported by the nearly identical excitation spectra, recorded at
77 K and 298 K for HE and LE bands (Figures 4 and S7).
Thus, it is reasonable to propose that the initial excitation S0ĺSn
of the title complexes is followed by the relaxation to the S1 state,
presumably of IL (phosphane) nature, which then undergoes fast
3
intersystem crossing to the metal-perturbed ʌʌ* IL (T2) state of
the triplet manifold, possibly mixed with some XLCT character
(Figure 5). At low temperature, the lack of thermal energy kT
does not allow passing the barrier Ea that prevents populating
the lowest energy T1 state. The long lifetimes, associated with
this intermediate T2 excited state, indicate relatively weak SOC
that correlates well with its 3ʌʌ* nature. The given assignment is
additionally corroborated by 3ʌʌ*-luminophores
5
and
[(AuI)2BINAP]. Increasing the temperature depopulates the high
energy T2 level due to the transition of the system to the lowest
lying T1 state of (X+M)C origin (likely mixed with some XLCT).
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10.1002/chem.201705544
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steadily decreases within the given temperature range (270 K:
3.035 Å; 170 K: 3.013 Å; 120 K: 3.001 Å; 90 K: 2.995 Å, Figure
S8) even after the luminescence has already switched (i.e.
below 120 K for 7).
Apparently, this temperature-dependent optical functionality
should be considered as a synergistic effect of the molecular
structure and the crystal lattice, where the latter determines the
non-covalent intramolecular interactions and the molecular
conformations. Indeed, grinding the crystalline samples
completely removes thermochromic properties of compounds 6
and
7 and makes them virtually non-emissive at room
temperature; similar crystal-only behaviour has been described
for imidazolate Au3 phosphor.[13] In addition, complex 7 does not
show detectable LE luminescence in dmso solution both in liquid
and frozen forms that confirms its crucial dependence on the
presence of weak intra- (aurophilic) and intermolecular bonding,
which get disrupted in fluid medium and in the ground
amorphous state.
Figure 5. Proposed energy levels diagram of complex 7
Complex 8 shows weak light blue luminescence at room
temperature, but its substantial decomposition under irradiation
prevented proper investigation. Photoemission characteristics of
the mononuclear species 9 and 10 are reminiscent of those
The large Stokes shifts between the maxima of the excitation
and emission bands (12694 and 16167 cm-1 for 6 and 7) require
substantial structural distortions, which might occur in the
excited states. For the di- and polynuclear d10 complexes such
changes are often related to the shortening of the metal–metal
contacts,[33, 35] that seems to be a reasonable scenario for 6 and
7 too.
It is essential that significant involvement of the ligands orbital
into the T2 state and possible mixing with T1 state in 6 and 7
potentially offers an appealing possibility of tuning the dual
emission with respect to the wavelengths and energy barrier
between the triplet excited states.
acquired
earlier
for
their
close
analogues,
[(AuSCN)(XantPhos)][15] and [(AuCN)(tpdp)],[27] respectively
(Figure S9). The large difference in emission energies between
9 (Ȝem = 486 nm) and 10 (Ȝem = 640 nm) evidently arises from
unequal coordination numbers of gold(I) centers in these
compounds that is in compliance to the literature data on trigonal
and pseudo-tetrahedral Au species.[37] The excited states of 9
and 10 are tentatively associated with a mixture of XLCT
(iodideĺphosphane) and intra-phosphane ʌĺʌ* charge
transfer. In the case of 9 this assignment allows to rationalize
The presence of two thermally equilibrated triplet excited states
3
with predominant IL and 3MMLCT origin producing the dual HE
blue shifted emission compared to [(AuSCN)(XantPhos)] (Ȝem
=
and LE emission has been reported for the dynamic diplatinum
complexes,[36] where the energy barrier was related to the
structural changes dramatically altering metal–metal distances.
In the case of 6 and 7 the exact nature of the barrier between
the T2 and T1, however, remains an open question. The
examples of pronounced luminescence thermochromism, which
can be treated in terms of two distinct excited states, has been
described for a very limited number of gold(I) complexes,[11a, 11b,
511 nm) due to the effect of X ligand. However, both 10 and
[(AuCN)(tpdp)] emit at the same wavelength with very similar
lifetimes (1.8 and 1.4 ȝs) that might result from a small
contribution of XLCT (or L´LCT) transition into the emissive
triplet states for these tetracoordinate complexes. Nevertheless,
the X ligand has a non-innocent influence on luminescence
efficiency as the iodide induces 3-fold increase of the radiative
rate constant (kr = 1.5×105 s-1 for 10 vs 5.8×104 s-1 for
[(AuCN)(tpdp)]) and consequently enhances by a factor of 4 the
quantum yield of 10 (ĭem = 0.35) with respect to its cyanide
congener (ĭem = 0.08).[27] The radiative lifetime at 298 K for 10
(IJr = 5.1 ȝs) is compatible with thermally activated delayed
fluorescence behaviour,[38] which has been suggested earlier for
11d, 14a]
including few dinuclear compounds with XantPhos
ligand.[14b, 15] For the latter case the large hypsochromic shift of
the emission has been tentatively explained by the short Au…Au
contacts, which cannot contract further upon cooling.[15]
To check this hypothesis, we have carried out the VT XRD
analysis of compounds 1, 2, 6 and 7, the results of which are
summarized in Table S2. The structural data, in particular the
magnitude and the VT behaviour of Au…Au distances in the
ground state do not show any systematic influence on the
photophysical properties of these materials. Thus, the gold–gold
separation in thermochromic 6 at 298 K (2.984 Å) is shorter than
that in 1 (3.019 Å), the emission of which does not switch at low
temperature. In both cases, decreasing the temperature to 90 K
(95 K for 6) results in a very minor Au…Au contraction (ca. 0.005
Å for 1 and 0.007 Å for 6). For 7, however, the Au…Au
shortening (0.04 Å) is more significant when the temperature is
lowered from 270 K to 90 K. Moreover, the intermetallic contact
a
[Au(dppb)(PS)]
complex
(PS
=
2-
diphenylphosphinobenzenethiolate)[37c] and thus cannot be
excluded for 10, but still remains an extremely rare phenomenon
for the gold(I)-containing compounds.[35d]
Conclusions
The range of multidentate phosphane ligands was employed to
synthesize di- (1–7), mono- (8–10) and tetranuclear (11) gold
iodide complexes, the majority of which exhibit close aurophilic
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10.1002/chem.201705544
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contacts in the solid state, as confirmed by the results of
crystallographic analysis. Their luminescence properties
Acknowledgements
evidently reflect
a cooperative influence of intramolecular
Financial support from the Academy of Finland (grant 268993,
synthesis and XRD studies, I.O.K.) and the Russian Science
features (metal–metal bonding, stereochemistry and electronic
characteristics of the phosphanes) along with subtle but non-
innocent intermolecular non-covalent interactions, predominantly
governed by the crystal packing. Consequently, the emission
energies for these compounds at room temperature cover a
broad range of the visible spectrum from green (545 nm, 11) to
near-IR (698 nm, 2). We hypothesize that this variation is
Foundation
(grant
16-13-10064,
spectroscopic
and
photophysical studies, E.V.G., I.V.S.) is gratefully acknowledged.
Computational resources were provided by CSC, the Finnish IT
Center for Science (A.J.K.). The NMR and photophysical
measurements were performed using the following core facilities
at St. Petersburg State University Research Park: Centre for
Magnetic Resonance, Centre for Optical and Laser Materials
Research.
3
determined by the different contributions of (X+M)-centered and
3XLCT transitions into the emissive excited states, which are
eventually perturbed by the lattice-dependent intermolecular
interactions. The presence of short Au…Au distances does not
appear to be a necessary requirement to achieve efficient low
energy phosphorescence as the pseudo-tetracoordinate
mononuclear complex 10 exhibits emission maximum at 640 nm
with quantum yield of 0.35. In line with previous findings,[11a, 32]
ground state metal–metal separations do not offer an
unequivocally interpretable correlation with photophysical
parameters obtained for the title complexes. Therefore, for an
adequate description of the solid-state optical behavior of
compounds featuring metallophilic interactions, it is necessary to
Keywords: gold complexes • luminescence • thermochromism •
aurophilicity • phosphane ligands
[1]
[2]
X.-d. Wang, O. S. Wolfbeis, R. J. Meier, Chem. Soc. Rev. 2013, 42,
7834-7869.
a) Y. Cao, J. K. Nagle, M. O. Wolf, B. O. Patrick, J. Am. Chem.
Soc. 2015, 137, 4888í4891; b) X. Chen, X. Zhang, G. Zhang,
Chem. Commun. 2015, 51, 161-163; c) Q. Fang, J. Li, S. Li, R.
Duan, S. Wang, Y. Yi, X. Guo, Y. Qian, W. Huang, G. Yang, Chem.
Commun. 2017, 53, 5702-5705.
[3]
[4]
a) M. Han, Y. Tian, Z. Yuan, L. Zhu, B. Ma, Angew. Chem. Int. Ed.
2014, 53, 10908–10912; b) L. D. Earl, J. K. Nagle, M. O. Wolf,
Inorg. Chem. 2014, 53, 7106í7117.
consider their excited state properties preferably in a view of
supramolecular arrangement in the crystal.[13,
a) E. M. Gussenhoven, J. C. Fettinger, D. M. Pham, M. M. Malwitz,
A. L. Balch, J. Am. Chem. Soc. 2005, 127, 10838-10839; b) J. R.
Berenguer, J. Fernández, E. Lalinde, S. Sánchez, Chem. Commun.
2012, 48, 6384–6386; c) T. Hofbeck, Y. C. Lam, M. Kalbáþ, S.
Záliš, A. J. Vlþek, H. Yersin, Inorg. Chem. 2016, 55, 2441í2449.
a) K. R. Kyle, C. K. Ryu, J. A. DiBenedetto, P. C. Ford, J. Am.
Chem. Soc. 1991, 113, 2954-2965; b) H. Kitagawa, Y. Ozawa, K.
Toriumi, Chem. Commun. 2010, 46, 6302–6304; c) S. Perruchas,
C. Tard, X. F. Le Goff, A. Fargues, A. Garcia, S. Kahlal, J.-Y.
Saillard, T. Gacoin, J.-P. Boilot, Inorg. Chem. 2011, 50, 10682–
10692; d) S. Perruchas, N. Desboeufs, S. b. Maron, X. F. Le Goff,
A. Fargues, A. Garcia, T. Gacoin, J.-P. Boilot, Inorg. Chem. 2012,
51, 794í798; e) Q. Benito, X. F. Le Goff, S. b. Maron, A. Fargues,
A. Garcia, C. Martineau, F. Taulelle, S. Kahlal, T. Gacoin, J.-P.
Boilot, S. Perruchas, J. Am. Chem. Soc. 2014, 136, 11311í11320;
f) Q. Benito, X. F. Le Goff, G. Nocton, A. Fargues, A. Garcia, A. l.
Berhault, S. Kahlal, J.-Y. Saillard, C. Martineau, J. Trébosc, T.
Gacoin, J.-P. Boilot, S. Perruchas, Inorg. Chem. 2015, 54,
4483í4494.
33]
The crucial
importance of the ordered solid matrix is demonstrated by the
bimetallic luminophores 6 and 7, which reveal the presence of
two coupled triplet excited states T2 and T1 of IL 3ʌʌ* and
3(X+M)C (mixed with 3XLCT) origin, respectively. Due to the
energy barrier between the T2 and T1, crystalline 6 and 7 exhibit
high and low energy emissions with thermally variable intensities
ratio. These excited states T2 and T1 are equilibrated at the
temperatures above 170 K and lead to LE phosphorescence
under the ambient conditions, while at 77 K a dramatic
hypsochromic shift of the emission (up to 5750 cm-1, 7) is
detected. Such thermally induced switching highlights the
significance of both individual molecular structure and the
supramolecular lattice effects on the unconventional optical
functionality of the given class of phosphors. Despite it is still
difficult to rationalize and predict the exact relationships between
[5]
[6]
E. I. Musina, A. V. Shamsieva, I. D. Strelnik, T. P. Gerasimova, D.
B. Krivolapov, I. E. Kolesnikov, E. V. Grachova, S. P. Tunik, C.
Bannwarth, S. Grimme, S. A. Katsyuba, A. A. Karasik, O. G.
Sinyashin, Dalton Trans. 2016, 45, 2250–2260.
molecular
photophysical performance of this type of compounds, the
results point to promising potential of simple gold(I)
stereochemistry,
crystal
packing
and
the
[7]
M. S. Deshmukh, A. Yadav, R. Pant, R. Boomishankar, Inorg.
Chem. 2015, 54, 1337í1345.
[8]
J.-H. Wang, M. Li, J. Zheng, X.-C. Huang, D. Li, Chem. Commun.
2014, 50, 9115-9118.
a
[9]
B. Li, R.-W. Huang, J.-H. Qin, S.-Q. Zang, G.-G. Gao, H.-W. Hou,
T. C. W. Mak, Chem. Eur. J. 2014, 20, 12416–12420.
S.-L. Li, M. Han, B. Wu, J. Wang, F.-Q. Zhang, X.-M. Zhang, Sci.
phosphane-iodide complexes to serve as efficient and tunable
temperature-responsive materials.
[10]
[11]
Rep. 2017, 7, 13058.
a) Z. Assefa, B. G. McBurnett, R. J. Staples, J. P. Fackler, Inorg.
Chem. 1995, 34, 4965-4972; b) B. Weissbart, D. V. Toronto, A. L.
Balch, D. S. Tinti, Inorg. Chem. 1996, 35, 2490-2496; c) Y.-A. Lee,
J. E. McGarrah, R. J. Lachicotte, R. Eisenberg, J. Am. Chem. Soc.
2002, 124, 10662–10663; d) J. Liang, Z. Chen, J. Yin, G.-A. Yu, S.
H. Liu, Chem. Commun. 2013, 49, 3567--3569; e) C. Jobbágy, A.
Deák, Eur. J. Inorg. Chem. 2014, 4434–4449.
Experimental Section
Syntheses, details of X-ray structural determination and photophysical
measurements are given in the supporting information.
[12]
M. A. Omary, M. A. Rawashdeh-Omary, M. W. A. Gonser, O.
Elbjeirami, T. Grimes, T. R. Cundari, H. V. K. Diyabalanage, C. S.
P. Gamage, H. V. R. Dias, Inorg. Chem. 2005, 44, 8200-8210.
M. M. Ghimire, V. N. Nesterov, M. A. Omary, Inorg. Chem. 2017,
56, 12086í12089.
a) H. Xiao, Y.-X. Weng, W.-T. Wong, T. C. W. Mak, C.-M. Che, J.
Chem. Soc., Dalton Trans. 1997, 221-226; b) A. Pintado-Alba, H.
de la Riva, M. Nieuwhuyzen, D. Bautista, P. R. Raithby, H. A.
CCDC 1586836-1586852 contain the supplementary crystallographic
data for this paper. These data are provided free of charge by The
Cambridge Crystallographic Data Centre. See the Supporting Information
for experimental details.
[13]
[14]
This article is protected by copyright. All rights reserved.

10.1002/chem.201705544
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FULL PAPER
Sparkes, S. J. Teat, J. M. López-de-Luzuriaga, M. C. Lagunas,
Dalton Trans. 2004, 3459–3467.
P. Baranyai, G. Marsi, A. Hamza, C. Jobbágy, A. Deák, Struct.
Chem. 2015, 26, 1377–1387.
a) D. Fernandez, M. I. Garcia-Seijo, M. Bardaji, A. Laguna, M. E.
Garcia-Fernandez, Dalton Trans. 2008, 2633–2642; b) S. H. Lim,
M. M. Olmstead, A. L. Balch, Chem. Sci. 2013, 4, 311–318; c) D. T.
Walters, K. R. England, K. B. Ghiassi, F. Z. Semma, M. M.
Olmstead, A. L. Balch, Polyhedron 2016, 117, 535–541.
M. A. Bennett, S. K. Bhargava, D. C. R. Hockless, L. L. Welling, A.
C. Willis, J. Am. Chem. Soc. 1996, 118, 10469-10478.
D. V. Partyka, J. B. I. Updegraff, M. Zeller, A. D. Hunter, T. G. Gray,
Dalton Trans. 2010, 39, 5388–5397.
[29]
[30]
A. Deák, C. Jobbágy, G. Marsi, M. Molnár, Z. Szakács, P.
Baranyai, Chem. Eur. J. 2015, 21, 11495–11508.
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, 12196í12206.
a) D. V. Partyka, T. S. Teets, M. Zeller, J. B. Updegraff, A. D.
Hunter, T. G. Gray, Chem. Eur. J. 2012, 18, 2100–2112; b) 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.
a) C. King, J. C. Wang, M. N. I. Khan, J. P. J. Fackler, Inorg. Chem.
1989, 28, 2145–2149; b) W. B. Jones, J. Yuan, R.
Narayanaswamy, M. A. Young, R. C. Elder, A. E. Bruce, M. R. M.
Bruce, Inorg. Chem. 1995, 34, 1996-2001.
K. N. Jarzembska, R. KamiĔski, B. Fournier, E. b. Trzop, J. D.
Sokolow, R. Henning, Y. Chen, P. Coppens, Inorg. Chem. 2014,
53, 10594í10601.
J. Nitsch, F. Lacemon, A. Lorbach, A. Eichhorn, F. Cisnetti, A.
Steffen, Chem. Commun. 2016, 52, 2932-2935.
a) M. A. Omary, H. H. Patterson, Inorg. Chem. 1998, 37, 1060–
1066; b) G. S. M. Tong, S. C. F. Kui, H.-Y. Chao, N. Zhu, C.-M.
Che, Chem. Eur. J. 2009, 15, 10777–10789; c) M. E. S. Moussa, S.
Evariste, H.-L. Wong, L. Le Bras, C. Roiland, L. Le Polles, B. Le
Guennic, K. Costuas, V. W.-W. Yam, C. Lescop, Chem. Commun.
2016, 52, 11370-11373; d) A. Belyaev, T. Eskelinen, T. M. Dau, Y.
Y. Ershova, S. P. Tunik, A. S. Melnikov, P. Hirva, I. O. Koshevoy,
Chem. Eur. J. 2018, 10.1002/chem.201704642.
[15]
[16]
[31]
[32]
[33]
[17]
[18]
[19]
[20]
[21]
[22]
[23]
J. Zank, A. Schier, H. Schmidbaur, J. Chem. Soc., Dalton Trans.
1998, 323-324.
a) P. Pyykkö, Chem. Soc. Rev. 2008, 37, 1967-1997; b) H.
Schmidbaur, A. Schier, Chem. Soc. Rev. 2012, 41, 370-412.
J. Ramírez, M. Sanaú, E. Fernández, Angew. Chem. Int. Ed. 2008,
47, 5194–5197.
a) P. Pyykko, F. Mendizabal, Chem. Eur. J. 1997, 3, 1458; b) E. R.
T. Tiekink, J.-G. Kang, Coord. Chem. Rev. 2009, 253, 1627–1648.
a) A. A. Mohamed, J. A. Krause Bauer, A. E. Bruce, M. R. M.
Bruce, Acta Cryst. 2003, C59, m84-m86; b) N. Yoshinari, N. Kitani,
T. Tsukuda, T. Konno, Acta Cryst. 2011, E67, m121.
S. K. Bhargava, F. Mohr, M. A. Bennett, L. L. Welling, A. C. Willis,
Organometallics 2000, 19, 5628-5635.
[34]
[35]
[24]
[25]
[26]
C. Jobbágy, P. Baranyai, P. Szabó, T. Holczbauer, B. Rácz, L. Li,
P. Naumov, A. Deák, Dalton Trans. 2016, 12569–12575.
a) P. Baranyai, G. Marsi, C. Jobbágy, A. Domján, L. Oláh, A. Deák,
Dalton Trans. 2015, 44, 13455–13459; b) H. Ito, T. Saito, T.
Miyahara, C. Zhong, M. Sawamura, Organometallics 2009, 28,
4829–4840; c) J. Zank, A. Schier, H. Schmidbaur, J. Chem. Soc.,
Dalton Trans. 1999, 415-420.
G. Chakkaradhari, Y.-T. Chen, A. J. Karttunen, M. T. Dau, J. Jänis,
S. P. Tunik, P.-T. Chou, M.-L. Ho, I. O. Koshevoy, Inorg. Chem.
2016, 55, 2174–2184.
[36]
[37]
C. Zhou, Y. Tian, Z. Yuan, M. Han, J. Wang, L. Zhu, M. S. Tameh,
C. Huang, B. Ma, Angew. Chem. Int. Ed. 2015, 54, 9591–9595.
a) S. H. Lim, J. C. Schmitt, J. Shearer, J. Jia, M. M. Olmstead, J. C.
Fettinger, A. L. Balch, Inorg. Chem. 2013, 52, 823í831; b) R.
Visbal, I. Ospino, J. M. Lopez-de-Luzuriaga, A. Laguna, M. C.
Gimeno, J. Am. Chem. Soc. 2013, 135, 4712í4715; c) M. Osawa,
I. Kawata, R. Ishii, S. Igawa, M. Hashimoto, M. Hoshino, J. Mater.
Chem. C 2013, 1, 4375-4383.
[27]
[28]
[38]
R. Czerwieniec, M. J. Leitl, H. H. H. Homeier, H. Yersin, Coord.
Chem. Rev. 2016, 325, 2–28.
P. Pyykko, Chem. Rev. 1997, 97, 597-636.
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Entry for the Table of Contents
FULL PAPER
A delicate interplay of intramolecular
features and subtle intermolecular
interactions is capable to produce
gold(I) complexes with distinct
Nina Glebko, Thuy Minh Dau, Alexei S.
Melnikov, Elena V. Grachova, Igor V.
Solovyev, Andrey Belyaev, Antti J.
Karttunen*, Igor O. Koshevoy*
thermochromic luminescence,
Page No. – Page No.
resulting from reversible switching
between two coupled excited states.
Luminescence thermochromism of
gold(I) phosphane-iodide
complexes: a rule or an exception?
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