Spectroscopic and phosphorescent modulation in triphosphine-supported PtAg2 heterotrinuclear alkynyl complexes

Article abstract of DOI:10.1021/ic4000457

A series of highly phosphorescent PtAg₂ heterotrinuclear alkynyl complexes with bis(diphenylphosphinomethyl)phenylphosphine (dpmp) were prepared and characterized structurally. The solution phosphorescence with various emitting colors is systematically modulated by modifying substituents as well as π-conjugated systems in aromatic acetylides. The crystals, powders, or films exhibit reversible stimuli-responsive phosphorescence changes upon exposure to vapor of MeCN, pyridine, DMF, etc., resulting from perturbation of d ⁸-d¹⁰ metallophilic interaction in the excited states as a consequence of the formation/disruption of Ag-solvent bonds. Both experimental and time-dependent density functional theory (TD-DFT) studies demonstrate that d⁸-d¹⁰ metallophilic interaction exerts a crucial role on phosphorescent characteristics due to the PtAg₂ cluster-based ³[d → p] state. This study affords a paradigm for phosphorescence modulation in d⁸-d¹⁰ heteronuclear complexes.

Full text of DOI:10.1021/ic4000457

Article
pubs.acs.org/IC
Spectroscopic and Phosphorescent Modulation in Triphosphine-
Supported PtAg2 Heterotrinuclear Alkynyl Complexes
Li-Yi Zhang, Liang-Jin Xu, Xu Zhang, Jin-Yun Wang, Jia Li, and Zhong-Ning Chen*
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences,
Fuzhou, Fujian 350002, China
S
* Supporting Information
ABSTRACT: A series of highly phosphorescent PtAg2 heterotrinu-
clear alkynyl complexes with bis(diphenylphosphinomethyl)-
phenylphosphine (dpmp) were prepared and characterized structurally.
The solution phosphorescence with various emitting colors is
systematically modulated by modifying substituents as well as π-
conjugated systems in aromatic acetylides. The crystals, powders, or
films exhibit reversible stimuli-responsive phosphorescence changes
upon exposure to vapor of MeCN, pyridine, DMF, etc., resulting from
perturbation of d8-d10 metallophilic interaction in the excited states as a
consequence of the formation/disruption of Ag−solvent bonds. Both
experimental and time-dependent density functional theory (TD-DFT)
studies demonstrate that d8-d10 metallophilic interaction exerts a crucial
role on phosphorescent characteristics due to the PtAg2 cluster-based
3[d → p] state. This study affords a paradigm for phosphorescence
modulation in d8−d10 heteronuclear complexes.
-withdrawing substituents, but also modifying π-conjugated
system in aromatic acetylide ligands. They exhibit dramatic
phosphorescence vaporchromism in the solid state upon
exposure to vapor of MeCN, pyridine, or DMF having
coordination character to metal ions. Both experimental and
computational studies demonstrate that the PtAg2 cluster-based
3[d → p] triplet excited state exerts a crucial role on the
phosphorescent characteristics.
INTRODUCTION
■
Phosphorescent emission of transition metal complexes occurs
mostly in coordination systems with d6, d8, or d10 metal ions.1,2
Phosphorescent metal complexes with d8 or d10 metal ions are
particularly interesting because additional d8-d8 or d10-d10
metallophilic interactions with the energy comparable to that
of hydrogen bonds not only exert extra stability on the
aggregate structures,3 but also play a key role in determining
the phosphorescent characteristic.1,2 As strong-field ligands
with comparable coordination capability, both acetylide and
phosphine are facile for the coordination to d8 or d10 metal
ions,1−3 resulting in largely raising the d-d state to relatively
inaccessible energies so that an emissive triplet state is achieved.
Although a limited number of d8-d10 heterometallic complexes
have been prepared,4−26 few systematical studies on their
photophysical properties have been performed.9,10 In fact,
systematic modulation of the phosphorescence properties
relevant to d8-d10 metallophilic interactions remains to be
performed.
Herein, we focus on systematic modulation of spectroscopic
and phosphorescence properties by the elaborate design of
PtAg2 heterotrinuclear alkynyl complexes using bis-
(diphenylphosphinomethyl)phenylphosphine (dpmp) as a
bridging ligand. These doubly dpmp-supported PtAg2 alkynyl
complexes exhibit mostly brilliant phosphorescence in both
fluid solutions and solid states at ambient temperature. The
solution phosphorescence with various visible emitting colors
from the blue to the red spectral region is systematically
modulated by not only introducing electron-donating or
RESULTS AND DISCUSSION
■
Synthesis and Characterization. Initially, the reaction
was performed by mixing equimolar trans-Pt(PPh3)2(C
25,26
CPh)2 with [Ag3(dpmp)2](ClO4)3
in CH2Cl2. The
products were separated by silica gel column chromatography.
While the first colorless band was identified as [Ag(PPh3)4]-
(ClO4), yellow heterotrinuclear complex [PtAg2(dpmp)2(C
CPh)2]](ClO4)2 (1) was collected as the second band in 80%
yield. Obviously, the formation of 1 is involved in the
substitution of Pt-bound PPh3 with P donors of dpmp. On
the basis of the stoichiometric ratio of Pt/Ag/dmpm = 1: 2: 2
in complex 1, the synthetic procedure was then optimized by
mixing equiv. Ag(tht)(ClO4) and dpmp, followed by the
addition of 0.5 equiv. Pt(PPh3)2(CCPh)2. Complex 1 was
indeed accessed in higher yield (85%) as expected. With this
synthetic procedure, a series of PtAg2 complexes (1−9, Scheme
1) with various substituents in aromatic acetylides were thus
Received: January 8, 2013
© XXXX American Chemical Society
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Scheme 1. Synthetic Route for PtAg2 Complexes
prepared in 79−86% yields. To modulate the spectroscopic and
phosphorescent properties by changing the π-conjugated
system, PtAg2 complexes (10−12) with a progressively
extended π-system in the aromatic acetylides were also
prepared.
Ten structures of PtAg2 complexes were determined by X-ray
crystallography, including 1·2CH2Cl2, 2·CH2Cl2, 4·4CH2Cl2,
4(MeCN)·MeCN, 5·2CH2Cl2·2H2O, 5(py)2·2py, 9·2acetone,
9(DMF)2·2DMF, 9(MeCN)2·2Et2O, and 9(py)2·2py. Selected
atomic distances and bond angles are provided in the
Supporting Information (Tables S3 and S4). The structures
depicted in Figure 1 reveal unambiguously that PtAg2 centers
are doubly linked by dpmp, which are highly stabilized by
substantial Pt−Ag contact as well as four five-membered
chelating rings. trans-Pt(CCR)2 unit is located at the middle
and two Ag(I) centers are at two sides.
The Ag−Pt−Ag angle is always 180° except for 2·CH2Cl2
(171.988(16)°, Figure S1) with one of the two silver(I) centers
bound to one perchlorate and 9(DMF)2·2DMF
(151.735(15)°) with two Ag−DMF bonds (Figure 1d). Quite
short Pt···Ag (2.9−3.1 Å) distances suggest the presence of
significant Pt−Ag interaction.3,9,10 The Pt···Ag distances are
comparable to those found in doubly Ph2PCH2PPh2 or
Ph2PNPPh2 linked PtII−AgI complexes.10 For 2·CH2Cl2
(Figure S1), the distance of Pt1···Ag2 (3.0221(6) Å) with
Ag2 bound to one O atom of perchlorate is obviously longer
than that of Pt1···Ag1 (2.9469(6) Å) without Ag1−O linkage.
The Pt···Ag distances in 9(MeCN)2·2Et2O (3.0774(7) Å,
Figure 1b), 9(py)2·2py (3.0323(5) Å, Figure 1c), and
9(DMF)2·2DMF (3.0455(7) and 3.0472(8) Å, Figure 1d)
with Ag−solvent bonds are obviously longer than that in
9·2acetone (2.9782(10) Å, Figure 1a) without Ag−solvent
bonds. Compared with the Pt···Ag distance in 4·4CH2Cl2
(2.9555(5) Å, Figure S2a), those in 4(MeCN)·MeCN
(3.0258(4) and 3.0409(5) Å, Figure S2b) also become longer
Figure 1. Perspective views (30% thermal ellipsoids) of cationic PtAg2
complexes in 9·2acetone (a), 9(MeCN)2·2Et2O (b), 9(py)2·2py (c),
and 9(DMF)2·2DMF (d), showing obviously elongated Ag···Pt
distance upon the formation of Ag−solvent bonds. Phenyl rings on
the phosphorus atoms are omitted for clarity.
due to the formation of Ag−NCMe bonds. Similarly, the
Pt···Ag distance in pyridine-bound complex 5(py)2·2py
(3.0077(5) Å) is obviously longer than that in
5·2CH2Cl2·2H2O (2.9318(10) Å). Accordingly, the formation
of Ag−OClO3 or Ag−solvent bonds results in much longer
Pt···Ag distances.
The platinum(II) center is located at square-planar environ-
ment with trans-arranged P2C2 donors. The silver(I) center
exhibits linear (Figure 1a), T-shaped or trigonal-planar
geometry (Figures S1 and S2a) in the absence of the Ag−
solvent bond. Upon the formation of Ag−solvent bonds, the
silver(I) center exhibits a distorted T-shaped or trigonal-planar
environment (Figure 1c) in the absence of Ag−acetylide bonds,
whereas a tetrahedral geometry (Figure 1b) in the presence of
Ag−acetylide bonds.
1
The variable-temperature H NMR spectra of complex 9
(Figure S4) at 293−193 K suggest that the presence of fluxional
structures in CD2Cl2 depending on the formation of the Ag−
acetylide/perchlorate bond (Figure 1). Three singlets due to
phenyl proton (Ha) with different intensity at 293 K (Figure
S4) were distinctly changed in both chemical shift and relative
intensity as the temperature was gradually lowered to 193 K.
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Similarly, three singlets for Hb (OCH3 at two sides) or two
singlets for Hc (OCH3 at the middle) were also variable in both
chemical shift and relative intensity when the temperature was
lowered to 193 K. The presence of two or three signals for each
equivalent proton together with temperature-dependent
chemical shift and relative intensity revealed unambiguously
three or more fluxional structures (Figure S4) depending on
whether or not the formation of Ag−acetylide or Ag−OClO3
bonds, as demonstrated unambiguously by X-ray crystallog-
raphy. The relative percentages of various fluxional structures
are alterable depending on the temperature and the solvents.
The 31P NMR spectra (Figure S5) are characteristic of Pt−P,
Table 1. The UV-Vis Absorption Spectral Data of PtAg2
Complexes 1−12 in CH2Cl2 Solutions
complex
λabs/nm (ε/dm3 mol−1 cm−1
)
1
2
3
231 (82280), 270 (42570), 349 (29130), 402 (13470)
231 (88670), 269 (47490), 355 (32480), 397 (11520)
230 (83990), 269 (38150), 303 (24350), 345 (31920),
358 (31770), 382 (13300)
4
5
6
230 (79100), 269 (45260), 347 (26330), 411 (15210)
230 (78720), 268 (43350), 342 (24370), 423 (14230)
230 (95150), 268 (46550), 313 (24640), 345 (28460),
438 (17150)
7
229 (75240), 270 (40870), 342 (26500), 448 (14790)
230 (75440), 269 (37420), 339 (32040), 479 (15950)
230 (103000), 269 (43700), 383 (50000), 444 (14300)
230 (89100), 294 (56800), 345 (27200), 410 (16930)
Ag−P and P−P couplings with JPt−P = 2200−2600 Hz, JAg−P
=
8
400−600 Hz, and JP−P = 30−50 Hz. The ratio of integral area
between Pt− and Ag−bound P atoms is 1: 2, coinciding well
with their solid structures.
Computational Studies. Time-dependent DFT (TD-
DFT) studies were performed on complex 1 (Tables S5). As
depicted in Figure 2, the HOMO is mostly resident on
9
10
11
229 (93700), 278 (35500), 290 (40000), 360 (35100),
379 (37400), 420 (20600)
12
229 (103000), 278 (42300), 289 (47100), 357 (52200),
376 (53800), 445 (16000)
Figure 3. The UV−vis absorption spectra of PtAg2 complexes in
CH2Cl2 at ambient temperature, showing a progressive red-shift of the
low-energy bands with the increased electron-donating character of R
and R′ in phenylacetylide.
Figure 2. Spatial plots of the HOMO and LUMO of complex 1.
phenylacetylide (66.9%) and PtAg2 atoms (27.5%, 5d(Pt) and
4d(Ag)). The LUMO is uniformly distributed on dpmp
(43.2%), PtAg2 (34.0%, 6p(Pt) and 5p(Ag)) and phenyl-
acetylide (22.8%). Electronic transitions due to HOMO →
LUMO are thus ascribed to significant [π(CCR) →
π*(dpmp)] LLCT (ligand-to-ligand charge transfer) and
PtAg2 cluster centered [d → p] states with moderate [π →
π*(CCR)] IL (intraligand) character.
gradually blue-shifted because introducing one or two electron-
withdrawing CF3 to phenylacetylide would lower the HOMO
(mainly π orbital of phenylacetylide) level and thus increase the
HOMO−LUMO gap of LLCT and IL states. In contrast, the
low-energy absorption bands of 4 (411 nm), 5 (423 nm), 6
(438 nm), 7 (448 nm), and 8 (479 nm) with one or two But,
OMe, NH2, or NMe2 exhibit progressive red-shift compared
with 1 (402 nm) since introduction of electron-donating
substituents to phenylacetylide would raise the HOMO level
and thus reduce HOMO−LUMO gap of LLCT and IL states.
Thus, the spectral shift trend due to the electronic effects of R
or R′ coincides perfectly with the assignment that the low-
energy absorption bands display significant character of LLCT
and IL states.
Increasing π-conjugated system in the aromatic acetylide is
another feasible approach to induce red-shift of the low-energy
absorption bands. As depicted in Figure 4, the low-energy
absorption bands of PtAg2 complexes show stepwise red-shifts,
following 402 nm (1) → 410 nm (10) → 420 nm (11) → 445
nm (12). Since the HOMO (π orbital of aromatic acetylide)
level is increasingly raised with the extension of π-conjugated
system in aromatic acetylide, the HOMO−LUMO gap is
progressively reduced.
UV−vis Spectroscopic Properties. The UV−vis absorp-
tion spectra (Table 1) exhibit intense UV absorption bands at
<300 nm and medium energy bands at 320−380 nm,
originating mainly from ligand-centered transitions mixed
with some metal-perturbed character. The broad low-energy
bands at >380 nm are ascribed to significant [π(CCR) →
π*(dpmp)] LLCT and PtAg2 cluster based [d → p] states
together with moderate [π → π*(CCR)] IL character as
supported by TD-DFT studies. Solvent-dependent UV−vis
spectra (Figure S6) indicate that the low-energy absorption
bands show progressive blue-shift with the increase of solvent
polarity, following toluene → CH2Cl2 → ethyl acetate → THF
→ acetone → MeOH → MeCN → DMF → pyridine. This is
mostly ascribable to negative solvatochromism which is typical
of charge transfer transitions involving the LLCT state.9,10 The
formation of solvent−metal bonds is likely another factor
responsible for such a spectral blue-shift in coordination
solvents such as MeCN, DMF, and pyridine.
Phosphorescent Properties. Upon irradiation at λex > 300
nm, complexes 1−12 (Table 2) exhibit bright or brilliant
luminescence in both fluid CH2Cl2 solutions and solid states at
ambient temperature. Large Stokes shifts together with a
As shown in Figure 3, relative to the low-energy band of 1 (R
= R′ = H) at 402 nm, those of 2 (397 nm) and 3 (382 nm) are
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Figure 4. The UV−vis absorption spectra of PtAg2 complexes in
CH2Cl2 solutions at ambient temperature, showing a progressive red-
shift of the low-energy bands with an increased π-conjugated system in
aromatic acetylides.
Table 2. Luminescence Data of PtAg2 Complexes in Fluid
CH2Cl2 and Solid State at Ambient Temperature
Figure 5. The emission spectra and photographic images (irradiation
at 365 nm) of a series of PtAg2 complexes (2.0 × 10−5 M) in fluid
CH2Cl2 solutions, showing progressive red-shifted emission bands and
luminescence colors with an increased electron-donating capability of
R and R′ substituents in the phenylacetylides.
CH2Cl2
solid
λem/nm
τem/μs
Φem/%
λem/nm
τem/μs
Φem/%
1
490
476
463
502
524
552
604
625
543
504
563
661
0.08
0.014
0.37
0.13
1.46
4.72
0.04
0.78
5.15
4.33
16.30
35.90
1.0
500
491
467
504
520
548
593
618
555
529
558
658
1.32
1.48
5.80
1.47
2.09
2.63
1.84
1.01
4.98
4.32
16.34
1.03
27.3
44.4
9.7
2
3.4
3
9.3
463 nm (3) → 476 nm (2) → 490 nm (1) → 502 nm (4) →
524 nm (5) → 552 nm (6) → 604 nm (7) → 625 nm (8), in
which the phosphorescence color shows a progressive red-shift
in the order of deep blue (3) → blue (2) → cyan (1) → green
(4) → yellow-green (5) → yellow (6) → orange (7) → red
(8). It is obvious that the emission spectra are progressively
red-shifted with the gradually increased electron-donating
capability of R and R′ in CCC6H3(R′,R)-2,4 following CF3
→ H → But → OMe → NH2 → NMe2, ascribed to the
increasingly raised energy level of the HOMO (mainly π orbital
of acetylide) and thus gradually reduced HOMO−LUMO gap.
Such a spectral shift coincides perfectly with the assignment
4
3.5
74.1
28.6
40.2
24.0
2.8
5
14.3
22.5
weak
1.0
6
7
8
9
14.3
20.5
13.4
1.2
39.2
5.2
10
11
12
1.6
weak
microsecond or sub-microsecond range of lifetimes imply that
the luminescence is phosphorescent in nature with triplet
excited states. The emission spectra (Figure S7) are solvent-
dependent to afford 7−19 nm (270−715 cm−1) blue-shifts in
coordination solvents such as pyridine, DMF, MeCN, etc. due
to the formation of Ag−solvent bonds. The emission intensity
is enhanced with the increase of the concentrations at <10−4 M,
but self-quenching occurs in higher concentrations.
3
that the phosphorescence originates primarily from [π(C
CR) → π*(dpmp)] 3LLCT and 3[π → π*(CCR)] 3IL triplet
3
excited states with significant PtAg2 cluster centered [d → p]
character that is modified by substantial Pt−Ag contact
depending on the Pt···Ag distance.
The solution phosphorescence of PtAg2 complexes was also
modulated by introducing a more extended π-system in
aromatic acetylides. As depicted in Figure 6, the phosphor-
escence shows a progressive red-shift following 490 nm (1) →
504 nm (10) → 563 nm (11) → 661 (12) with cyan, green,
yellow, and red light emitting, respectively. This is readily
understandable because progressive increase of π-conjugated
system in aromatic acetylide would raise the π orbital level
(HOMO) and accordingly reduce the HOMO−LUMO gap of
3LLCT/3IL triplet excited states. With the progressive increase
of a π-conjugated system in aromatic acetylide ligands, the
phosphorescent lifetimes of PtAg2 complexes exhibit a gradual
increase following 0.08 μs (1) → 4.33 μs (10) → 16.30 μs (11)
→ 35.90 (12) in fluid CH2Cl2, ascribable likely to the gradually
enhanced IL character in aromatic acetylide ligands and the
progressively reduced [d → p] character in PtAu2 cluster.
Vapor-Responsive Phosphorescence Changes. Inter-
estingly, the phosphorescence in the solid state is mostly
sensitive to vapor of MeCN, DMF, pyridine, etc. with
coordination character. When powder, crystals, or films
(Figures 7 and 8, Figure S8) of these PtAg2 complexes are
exposed to vapor of MeCN, pyridine, or DMF, remarkable
emitting color changes occur within dozens of seconds to a few
These PtAg2 complexes display moderate phosphorescent
quantum yields in fluid CH2Cl2 solutions (Φem = 1.0−22.5%)
whereas much higher quantum yields in solid states (Φem
=
1
1.6−74.1%) at ambient temperature. As demonstrated by H
NMR spectral studies, fluxional structures are existent for PtAg2
complexes in fluid CD2Cl2 solutions, originating from
unsaturated coordination character on silver(I) centers which
tend to bind further to acetylide C or perchlorate O atoms.
Nevertheless, such Ag−C and Ag−O bonds are quite labile, so
that rapid formation/disruption of metastable coordination
bonds would become an effective nonradiative decay pathway,
thus deactivating the triplet excited states and reducing
significantly the phosphorescence efficiency in fluid solutions.
It is noteworthy that the phosphorescence in PtAg2 complexes
with CCC6H4NH2-4 or CCC6H4NMe2-4 is quite weak
due to the strong electron-donating character of -NH2 or
-NMe2, which favors intramolecular electron transfer so as to
quench significantly the emissive triplet state.
As shown in Figure 5, the phosphorescence in a series of
PtAg2 complexes was perfectly modulated by modifying the
substituent in aromatic acetylide. The emission maxima follow
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Figure 8. The emission spectra (a) and photographic images of
PMMA films (b) of 9 and the crystals (c) of 9(py)2·2py,
9(DMF)2·2DMF, 9(MeCN)2·2Et2O, and 9·2acetone under ambient
and UV (365 nm) light irradiation.
Figure 6. The emission spectra and photographic images of PtAg2
complexes 1 and 10−12 in fluid CH2Cl2 (2.0 × 10−5 M), showing a
progressive red-shift of the low-energy bands with increased π-
conjugated system in aromatic acetylide.
in 4·4CH2Cl2 (2.9555 Å), MeCN vapor triggered blue-shift of
the emission is mostly relevant to the formation of MeCN−Ag
bonds and the reduced Pt−Ag interaction in 4(MeCN)·MeCN
which would increase the HOMO−LUMO gap and thus the
emissive energy.
Upon exposure to pyridine vapor, the crystals of
5·2CH2Cl2·2H2O (Figure S8) converted to 5(py)2·2py with
both coordinated and solvated pyridine, in which green
emission at 520 nm turned to cyan luminescence at 490 nm
in a few minutes. Conversely, cyan-emitting crystals of
5(py)2·2py reverted reversibly to green-emitting
5·2CH2Cl2·2H2O upon exposure to CH2Cl2 vapor. TD-DFT
calculations were conducted on 5·2CH2Cl2·2H2O (Table S6)
and 5(py)2·2py (Table S7) using crystallographic parameters.
The HOMO−LUMO gap (Figure S11) in 5(py)2·2py (3.86
eV) is obviously larger than that in 5·2CH2Cl2·2H2O (3.45 eV)
as a consequence of the formation of Ag−pyridine coordination
bonds for the former. The calculated triplet state transition
energy in 5(py)2·2py (2.77 eV, Table S7) is obviously higher
than that in 5·2CH2Cl2·2H2O (2.49 eV, Table S6). Mayer bond
order calculation suggests that the Pt−Ag bond order in
5(py)2·2py (0.24) is distinctly smaller than that in
5·2CH2Cl2·2H2O (0.27). This is well correlated with a weaker
Pt−Ag interaction in 5(py)2·2py (dPt−Ag = 3.0077(5) Å) due to
a longer Pt···Ag distance than that in 5·2CH2Cl2·2H2O (dPt−Ag
= 2.9318(10) Å). Thus, the emission blue-shift of
5·2CH2Cl2·2H2O (520 nm) upon conversion to 5(py)2·2py
(490 nm) is ascribable to the formation of Ag−pyridine bonds
and consequently the reduced Pt−Ag interaction, which
perturbs the metal centers and increases the transition energy.
When complex 9 was crystallized in acetone, MeCN, DMF,
and pyridine, the isolated crystals of 9·2acetone,
9(MeCN)2·2Et2O, 9(DMF)2·2DMF and 9(py)2·2py exhibit
brilliant yellow, green, cyan, and cyan luminescence (Figure 8)
with the emission maxima at 556, 513, 497, and 490 nm,
respectively. Relative to 9·2acetone (556 nm) with solvate
acetone, a significant blue-shift of the emission in
9(MeCN)2·2Et2O (513 nm), 9(DMF)2·2DMF (497 nm), or
9(py)2·2py (490 nm) is ascribable to the bonding of MeCN,
DMF, or pyridine to silver(I) centers (Figure 1), in which the
Pt···Ag distances in 9(MeCN)2·2Et2O (3.08 Å),
9(DMF)2·2DMF (3.05 Å), or 9(py)2·2py (3.03 Å) are
Figure 7. Emission spectra (top) and photographic images (bottom)
of the crystals of 4(MeCN)·MeCN and 4·4CH2Cl2 under ambient
light (a) and UV (365 nm) light (b), showing reversible
interconversion between crystals 4(MeCN)·MeCN and 4·4CH2Cl2
upon exposing to CH2Cl2 or MeCN vapor.
minutes depending on the crystallinity of the solids or thickness
of the films, in which the emission bands show obvious blue-
shifts.
As depicted in Figure 7, the crystals of 4·4CH2Cl2 display
reversible phosphorescence vapochromism in response to vapor
of MeCN with the emission at 506 nm being blue-shifted to
480 nm. Upon exposure to MeCN vapor, green phosphor-
escence in the crystals of 4·4CH2Cl2 turned to blue emitting
due to formation of 4(MeCN)·MeCN containing both
coordinated and crystallized MeCN. Conversely, upon
exposure to CH2Cl2 vapor, blue emitting crystals of
4(MeCN)·MeCN reverted to green phosphorescent
4·4CH2Cl2 in a few minutes. Since the Pt···Ag distance in
4(MeCN)·MeCN (3.0258(4) Å) is obviously longer than that
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obviously longer than that in 9·2acetone (2.98 Å). Solvent
coordination induces distinct elongation in Pt···Ag distances,
and thus the reduction of Pt−Ag interaction may be the key
factor for blue-shift of the emission.
Dynamic emission spectral changes (Figure 9) were recorded
upon exposing the crystals of 9·2acetone to pyridine vapor, in
stacking, hydrogen bonding, host−guest affinity, reversible
isomerization, etc.27,28 A series of d10-d10 complexes with Au−
Tl, Au−Ag, and Au−Cu heterometallic arrays29,30 have been
demonstrated to exhibit remarkable luminescence changes in
response to vapors of coordination solvents due to reversible
formation/disruption of Tl/Ag/Cu−solvent bonds, thus
affecting the emissive states relevant to d10-d10 metallophilic
interaction. The PtAg2 complexes with significant phosphor-
escence vapochromism represent the first family of vapor-
responsive solid materials based on d8-d10 heteronuclear
complexes for detection of volatile organic compounds
(VOCs) with coordination character, resulting from perturba-
tion of d8-d10 metallophilic interaction in the excited states due
to the formation/disruption of Ag−solvent bonds.
CONCLUSIONS
■
Highly phosphorescent d8-d10 PtAg2 alkynyl complexes are
elaborately designed. The solution phosphorescence was
systematically modulated by modifying substituents as well as
π-conjugated systems in aromatic acetylide so as to achieve
bright phosphorescence with various emitting colors. The solid-
state phosphorescence is successfully modulated by external
stimulus. Crystals, powders, or films of these PtAg2 complexes
exhibit reversible stimuli-responsive phosphorescence switch
upon exposure to vapor of MeCN, pyridine, or DMF due to the
formation of solvent−Ag bonds, which elongates Pt···M
distances and accordingly reduces Pt−Ag interaction, thus
resulting in an obvious blue shift of the phosphorescence
emission. As demonstrated experimentally and theoretically, the
phosphorescence emission arises from significant [π(CCR)
→ π*(dpmp)] LLCT and PtAg2 cluster-based [d → p]
transitions that are modified by substantial Pt−Ag interaction
depending on the Pt···Ag distances, together with moderate [π
→ π*(CCR)] IL character.
Figure 9. Dynamic emission spectral changes upon exposure of the
crystals of (a) 9·2acetone to pyridine vapor, and (b) 9(py)2·2py to
acetone vapor.
which the emission at 556 nm is gradually blue-shifted to 490
nm within 5 min due to the formation of 9(py)2·2py.
Conversely, exposing the crystals of 9(py)2·2py to acetone
vapor induces progressive red-shift of the emission at 490−556
nm upon the conversion to 9·2acetone. The X-ray diffraction
(XRD) patterns recorded in a vapochromic cycle of 9·2acetone
⇆ 9(py)2·2py are depicted in Figure 10, showing unambigu-
EXPERIMENTAL SECTION
■
General Procedures and Materials. All manipulations were
conducted under a dry argon atmosphere using Schlenk techniques
and vacuum-line systems unless otherwise specified. The solvents were
dried, distilled, and degassed prior to use except that those for
spectroscopic measurements were of spectroscopic grade. Bis-
(diphenylphosphinomethyl)phenylphosphine (dpmp) was prepared
by a synthetic procedure described in the literature.31 Other reagents
were purchased from commercial sources and used as received unless
stated otherwise. The precursor complexes Pt(PPh3)2(CCR)2 were
prepared by reactions of Pt(PPh3)2Cl2 (0.5 mmol), alkynyl ligands
(1.1 mmol), CuI (1 mg), and NEt3 (1 mL) in chloroform (50 mL)
with stirring at 50 °C for 5 h. The products were purified by
chromatography on silica gel columns using CH2Cl2- petroleum ether
as eluent.
Figure 10. The XRD spectra recorded in a reversible vapochromic
cycle of 9(py)2·2py ⇆ 9·2acetone, showing variations of the PXRD
patterns from (c−d) in the process 9·2acetone → 9(py)2·2py, and
those from (f−g) in the reversed process 9(py)2·2py → 9·2acetone.
(a)/(h): The simulated pattern of 9·2acetone. (b) The measured
pattern of 9·2acetone. (e) The simulated pattern of 9(py)2·2py.
[PtAg2(dpmp)2(CCC6H5)2](ClO4)2 (1). To a CH2Cl2 (20 mL)
solution of dpmp (50.6 mg, 0.1 mmol) was added Ag(tht)(ClO4)
(29.5 mg, 0.1 mmol) with stirring for 30 min. Upon the addition of
Pt(PPh3)2(CCC6H5)2 (46.1 mg, 0.05 mmol), the solution became
pale yellow with stirring at ambient temperature for 4 h. The solution
was concentrated to 2 mL, which was chromatographed on a silica gel
column using CH2Cl2-MeCN (8:1) as eluent to afford the product as a
pale yellow solid. Yield: 85%. Anal. Calcd for C80H68Ag2Cl2O8P6Pt: C,
52.65; H, 3.76. Found: C, 52.68; H, 3.86. ESI-MS m/z (%): 1725.4
(100) [M−ClO4]+, 814.3 (10) [M−2ClO4]2+. IR (KBr) ν/cm−1:
2096w (CC), 1103s (ClO4). 1H NMR (CD2Cl2) δ/ppm: 7.96−7.89
(m, 6H), 7.77−7.65 (m, 6H), 7.54−7.35 (m, 22H), 7.28−7.16 (m,
8H), 7.15−7.06 (m, 6H), 7.03−6.94 (m, 6H), 6.74−6.70 (m, 2H),
6.65−6.63 (m, 1H), 6.40−6.37 (m, 2H), 6.36−6.34 (m, 1H), 5.04−
4.84 and 4.53−4.41 (m,4H), 4.14−4.06 and 3.97−3.88 (m, 4H). 31P
ously the interconversion between crystalline 9(py)2·2py and
9·2acetone through vapor sorption within a few minutes. Thus,
the vapor-triggered solid-state phosphorescence changes are
totally reversible.
Luminescence vapochromism has been found in some d6, d8,
and d10 metal complexes, arising mostly from vapor-triggered
variations in intramolecular or intermolclecular interactions
including metal−solvent bonds, metallophilic contacts, π−π
F
dx.doi.org/10.1021/ic4000457 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
NMR (CD2Cl2) δ/ppm: 11.5 (m, 1P, JPt−P = 2432 Hz, JP−P = 34.6
Hz), 3.9 (m, 2P, JAg−P = 527 Hz, JP−P = 37.2 Hz).
3H, J = 7.4 Hz), 6.99−6.91 (m, 3H), 6.64−6.60 (m, 2H),6.40−6.38
(d, 1H), 6.32−6.27 (m, 2H), 6.20−6.15 (m, 1H), 4.93−4.75 and
4.44−4.39 (m, 4H), 4.35−4.26 and 4.08−4.00 (m, 4H), 3.79, 3.77,
3.71, 3.70, 3.50, and 3.13 (s, 12H). 31P NMR (CD2Cl2) δ/ppm: 12.9
Instead, it was also prepared by the following synthetic procedure.
To a CH2Cl2 (20 mL) solution of [Ag3(dpmp)2](ClO4)3 (107.1 mg,
0.05 mmol) was added Pt(PPh3)2(CCPh)2 (46.1 mg, 0.05 mmol).
The solution changed to pale yellow upon stirring at ambient
temperature for 4 h. Upon the solution being concentrated to 2 mL, it
was chromatographed onto a silica gel column. The first colorless band
was eluted using CH2Cl2-MeCN (10: 1), which was identified as
Ag(PPh3)4(ClO4) (20 mg). The second band was eluted using
CH2Cl2-MeCN (8:1) to give the product as a yellow solid. Yield: 80%.
[PtAg2(dpmp)2(CCC6H4CF3-4)2](ClO4)2 (2). This compound
was prepared by the same synthetic procedure as that of 1 except for
using 1-ethynyl-4-trifluoromethylbenzene instead of phenylacetylene.
Yield: 79%. Anal. Calcd for C82H66Ag2Cl2F6O8P6Pt: C, 50.23; H, 3.39.
Found: C, 50.24; H, 3.48. ESI-MS m/z (%): 1861.6 (100) [M−
and 11.6 (m, 1P, JPt−P = 2456 Hz, JP−P = 34.4 Hz), 7.6 (m, 2P, JAg−P
=
517 Hz, JP−P = 36.7 Hz).
[PtAg2(dpmp)2(CCC6H4NH2-4)2](ClO4)2 (7). This compound
was prepared by the same synthetic procedure as that of 1 except for
using 1-ethynyl-4-aminobenzene instead of phenylacetylene. Yield:
82%. Anal. Calcd for C80H70Ag2Cl2N2O8P6Pt: C, 51.80; H, 3.80; N,
1.51. Found: C, 51.74; H, 3.92; N, 1.45. ESI-MS m/z (%): 1755.3
(100) [M−ClO4]+, 828.5 (5) [M−2ClO4]2+. IR (KBr) ν/cm−1: 2090w
1
(CC), 1102s (ClO4). H NMR (CD2Cl2) δ/ppm: 7.88−7.83 (m,
6H), 7.69−7.65 (m, 4H), 7.62−7.56 (m, 2H), 7.49−7.31 (m, 22H),
7.24−7.13 (m, 8H), 7.05−7.02 (t, 4H, J = 7.5 Hz), 6.96−6.89 (m,
3H), 6.67−6.63 (m, 2H), 6.40−6.36 (m, 1H), 6.28−6.22 (m, 3H),
6.19−6.15 (m, 3H), 4.89−4.70 and 4.44−4.27 (m, 4H),4.05−3.96 and
1
ClO4]+. IR (KBr) ν/cm−1: 2099w (CC), 1102s (ClO4). H NMR
3.88−3.76 (m, 8H). 31P NMR (CD2Cl2) δ/ppm: 11.7 (m, 1P, JPt−P
=
(CD2Cl2) δ/ppm: 7.94−7.87 (m, 6H), 7.75−7.64 (m, 6H), 7.50−7.31
(m, 22H), 7.27−6.93 (m, 18H), 6.74−6.70 (t, 2H, J = 7.7 Hz), 6.64−
6.62 (d, 1H, J = 8.3 Hz), 6.35−6.31 (m, 3H), 4.99−4.90 and 4.54−
4.46 (m, 4H), 4.16−4.07 and 3.97−3.89 (m, 4H). 31P NMR (CD2Cl2)
δ/ppm: 11.8 and 11.0 (m, 1P, JPt−P = 2392 Hz, JP−P = 34.1 Hz), 4.7
and 3.8 (m, 2P, JAg−P = 527 Hz, JP−P = 36.5 Hz).
2446 Hz, JP−P = 36.8 Hz), 3.6 (m, 2P, JAg−P = 521 Hz, JP−P = 36.5 Hz).
[PtAg2(dpmp)2(CCC6H4NMe2-4)2](ClO4)2 (8). This compound
was prepared by the same synthetic procedure as that of 1 except for
using 1-ethynyl-4-dimethylaminobenzene instead of phenylacetylene.
Yield: 81%. Anal. Calcd for: C84H78Ag2Cl2N2O8P6Pt·2CH2Cl2: C,
49.64; H, 3.97; N, 1.35. Found: C, 49.78; H, 4.04; N, 1.30. ESI-MS m/
z (%): 1811.3 (100) [M−ClO4]+. IR (KBr) ν/cm−1: 2090w (CC),
1097s (ClO4). 1H NMR (CD2Cl2) δ/ppm: 7.87−7.82 (m, 6H), 7.69−
7.64 (m, 4H), 7.62−7.57 (m, 2H), 7.48−7.31 (m, 22H), 7.24−7.12
(m, 8H), 7.06−7.04 (t, 4H, J = 7.4 Hz), 6.96−6.90 (m, 4H), 6.67−
6.63 (m, 2H),6.49−6.41 (m, 2H), 6.31−6.30 (d, 4H, J = 5.0 Hz),
4.88−4.70 and 4.44−4.27 (m, 4H), 4.07−3.99 and 3.90−3.81 (m,
4H), 2.94, 2.90, and 2.89 (s, 12H). 31P NMR (CD2Cl2) δ/ppm: 11.6
[PtAg2(dpmp)2(CCC6H3(CF3)2-2,4)2](ClO4)2 (3). This com-
pound was prepared by the same synthetic procedure as that of 1
except for using 1-ethynyl-2,4-bis-trifluoromethylbenzene instead of
phenylacetylene. Yield: 82%. Anal. Calcd for C84H64Ag2Cl2F12O8P6Pt:
C, 48.11; H, 3.08. Found: C, 48.26; H, 3.05. ESI-MS m/z (%): 1997.0
(100) [M−ClO4]+, 1790.1 (30) [M−AgClO4−ClO4]+, 948.4 (35)
1
[M−2ClO4]2+. IR (KBr) ν/cm−1: 2105w (CC), 1103s (ClO4). H
NMR (CD2Cl2) δ/ppm: 8.07−8.02 (m, 6H), 7.98−7.93 (m, 1H),
7.86−7.82 (m, 3H), 7.78−7.23 (m, 2H), 7.62−7.28 (m, 34H), 7.21−
6.13 (m, 4H), 7.01−6.95 (m, 3H), 6.89−6.85 (m, 3H), 4.74−4.68 and
4.46−4.50 (m, 4H), 4.40−4.35 and 3.99−3.94 (m, 4H). 31P NMR
(CD2Cl2) δ/ppm: 8.6 (m, 1P, JPt−P = 2384 Hz, JP−P = 35.2 Hz), 7.8
(m, 2P, JAg−P = 509 Hz, JP−P = 36.8 Hz).
(m, 1P, JPt−P = 2432 Hz, JP−P = 34.2 Hz), 4.0 and 3.2 (m, 2P, JAg−P
=
518 Hz, JP−P = 34.7 Hz).
[PtAg2(dpmp)2(CCC6H2(OMe)3-3,4,5)2](ClO4)2 (9). This com-
pound was prepared by the same synthetic procedure as that of 1
except for the use of 5-ethynyl-1,2,3-trimethoxybenzene instead of
phenylacetylene. Yield: 86%. Anal. Calcd for C86H80Ag2Cl2O14P6Pt: C,
51.51; H, 4.02. Found: C, 51.56; H, 3.99. ESI-MS m/z (%): 1905.6
(100) [M−ClO4]+. IR (KBr) ν/cm−1: 2092w (CC), 1099s (ClO4).
1H NMR (CD2Cl2) δ/ppm: 7.89−7.81 (m, 6H), 7.75−7.70 (m, 3H),
7.63−7.58 (m, 3H), 7.48−7.34 (m, 20H), 7.31−7.27 (t, 1H, J = 7.4
Hz), 7.23−7.19 (t, 3H, J = 7.5 Hz), 7.15−7.10(m, 3H), 7.09−7.01 (m,
6H), 6.94−6.85(m, 3H), 6.68−6.64 (m, 2H), 5.79, 5.76, and 5.65 (s,
4H), 5.06−4.87, 4.68−4.51 (m, 4H), 4.14−4.05, 3.93−3.84 (m, 4H),
3.67, 3.64, 3.45,3.41,3.38 (s, 18H). 31P NMR (CD2Cl2) δ/ppm:
11.5(m, 1P, JPt−P = 2430 Hz, JP−P = 35.8 Hz), 4.0 (m, 2P, JAg−P = 521
Hz, JP−P = 36.7 Hz).
[PtAg2(dpmp)2(CCbph-4)2](ClO4)2 (10). This compound was
prepared by the same synthetic procedure as that of 1 except for the
use of 4-ethynylbiphenyl instead of phenylacetylene. Yield: 86%. Anal.
Calcd for C92H76Ag2Cl2O8P6Pt: C, 55.89; H, 3.87. Found: C, 55.94; H,
3.90. ESI-MS m/z (%): 1877.3 (100) [M−ClO4]+. IR (KBr) ν/cm−1:
2099w (CC), 1096s (ClO4). 1H NMR (DMSO) δ/ppm: 7.94−7.84
(m, 4H), 7.68−7.52 (m, 20H), 7.52−7.38 (m, 13H), 7.35−7.21 (m,
14H), 7.20−7.12 (m 7H), 7.12−7.04 (t, 3H, J = 7.5 Hz), 6.83−6.76(t,
3H, J = 7.4 Hz), 6.68−6.62 (d, 2H, J = 8.0 Hz), 6.56−6.49 (d, 2H, J =
8.1 Hz), 4.52−4.36 (m, 4H), 3.78−3.66 (m, 4H). 31P NMR (DMSO)
δ/ppm: 14.63(m, 1P, JPt−P = 2551 Hz, JP−P = 46.8 Hz), −5.17 (m, 2P,
JAg−P = 460 Hz, JP−P = 41.7 Hz).
[PtAg2(dpmp)2(CCC6H4But-4)](ClO4)2 (4). This compound
was prepared by the same synthetic procedure as that of 1 except
for using 1-ethynyl-4-butylbenzene instead of phenylacetylene. Yield:
82%. Anal. Calcd for C88H84Ag2Cl2O8P6Pt·3H2O: C, 53.08; H, 4.56.
Found: C, 53.05; H, 4.65. ESI-MS m/z (%): 1837.9 (25) [M−ClO4]+,
869.0 (100) [M−2ClO4]2+. IR (KBr) ν/cm−1: 2095w (CC), 1101s
1
(ClO4). H NMR (CD2Cl2) δ/ppm: 7.94−7.87 (m, 6H), 7.75−7.63
(m, 6H), 7.51−7.31 (m, 25H), 7.26−7.15 (m, 7H), 7.08−7.04 (t, 5H,
J = 7.5 Hz), 7.00−6.93 (m, 3H), 6.73−6.63(m, 3H),6.38−6.34 (m,
3H), 5.05−4.86 and 4.59−4.43 (m, 4H), 4.16−4.07 and 3.97−3.89
(m, 4H), 2.53, 2.49, and 2.48 (s, 18H). 31P NMR (CD2Cl2) δ/ppm:
11.7 and 11.0 (m, 1P, JPt−P = 2442 Hz, JP−P = 35.3 Hz), 4.6 (m, 2P,
JAg−P = 527 Hz, JP−P = 37.0 Hz).
[PtAg2(dpmp)2(CCC6H4OMe-4)2](ClO4)2 (5). This compound
was prepared by the same synthetic procedure as that of 1 except for
using 1-ethynyl-4-methoxybenzene instead of phenylacetylene. Yield:
82%. Anal. Calcd for C82H72Ag2Cl2O10P6Pt: C, 52.25; H, 3.85. Found:
C, 52.38; H, 3.90. ESI-MS m/z (%): 1785.5 (100) [M−ClO4]+. IR
(KBr) ν/cm−1: 2090w (CC), 1095s (ClO4). 1H NMR (CD2Cl2) δ/
ppm: 7.92−7.85 (m, 6H), 7.73−7.62 (m, 6H), 7.49−7.31 (m, 22H),
7.25−7.13 (m, 7H), 7.07−7.03 (t, 4H, J = 7.5 Hz), 6.98−6.90 (m,
3H), 6.69−6.61(m, 3H),6.53−6.46 (m, 4H), 6.29−6.26 (m, 3H),
4.92−4.85 and 4.48−4.42 (m, 4H), 4.09−4.01 and 3.92−3.85 (m,
4H), 3.77 and 3.71 (s, 6H). 31P NMR (CD2Cl2) δ/ppm: 11.8 and 10.9
[PtAg2(dpmp)2(CCphen-9)2](ClO4)2 (11). This compound was
prepared by the same synthetic procedure as that of 1 except for the
use of 9-ethynyl-phenanthrene instead of phenylacetylene. Yield: 86%.
Anal. Calcd for C96H76Ag2Cl2O8P6Pt: C, 56.93; H, 3.78. Found: C,
56.99; H, 3.85. ESI-MS m/z (%): 1925.7 (100) [M-ClO4]+. IR (KBr)
(m, 1P, JPt−P = 2442 Hz, JP−P = 35.3 Hz), 4.1 and 2.9 (m, 2P, JAg−P
519 Hz, JP−P = 36.9 Hz).
=
[PtAg2(dpmp)2(CCC6H3(OMe)2-2,4)2](ClO4)2 (6). This com-
pound was prepared by the same synthetic procedure as that of 1
except for using 1-ethynyl-2,4-dimethoxybenzene instead of phenyl-
acetylene. Yield: 82%. Anal. Calcd for C84H76Ag2Cl2O12P6Pt·3/
2CH2Cl2: C, 49.55; H, 3.84. Found: 49.92; H, 3.91. ESI-MS m/z
(%): 1845.8 (100) [M−ClO4]+. IR (KBr) ν/cm−1: 2097w (CC),
1098s (ClO4). 1H NMR (CD2Cl2) δ/ppm: 7.93−7.88 (m, 3H), 7.71−
7.61 (m, 9H), 7.47−7.23 (m, 26H), 7.18−7.13 (m, 6H), 7.09−7.06 (t,
1
ν/cm−1: 2093w (CC), 1097s (ClO4). HNMR (DMSO) δ/ppm:
8.79−8.72 (m, 4H), 7.89−7.79 (m, 5H), 7.72−7.42 (m, 27H), 7.41−
7.35 (t, 4H, J = 7.4 Hz), 7.34−7.26 (m, 2H), 7.26−7.11 (m,18H),
6.93−6.88(m, 1H), 6.85−6.68 (t, 4H, J = 7.7 Hz), 6.53, 6.42 (s, 2H),
6.30−6.24 (t, 1H, J = 7.6 Hz), 4.72−4.50 (m, 4H), 3.83−3.69 (m,
G
dx.doi.org/10.1021/ic4000457 | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
4H). 31P NMR (DMSO) δ/ppm: 16.60 (m, 1P, JPt−P = 2536 Hz, JP−P
= 41.9 Hz), −5.02 (m, 2P, JAg−P = 480 Hz, JP−P = 42.3 Hz).
SQUEEZE/PLATON due to severe disorder of these solvate
molecules in the lattices.
[PtAg2(dpmp)2(CCpyr-4)2](ClO4)2 (12). This compound was
prepared by the same synthetic procedure as that of 1 except for the
use of 4-ethynyl-pyrene instead of phenylacetylene. Yield: 86%. Anal.
Calcd for C100H76Ag2Cl2O8P6Pt·H2O: C, 57.43; H, 3.76. Found: C,
57.35; H, 3.83. ESI-MS m/z (%): 1973.0 (100) [M-ClO4]+. IR (KBr)
Computational Methodology. To understand the electronic and
spectroscopic properties as well as the nature of absorption and
emission origins, computational studies on 1 were implemented using
Gaussian 03 program package.34 First, the density functional theory
(DFT)35 method at the gradient-corrected correlation functional
PBE1PBE36 level was used to optimize the geometrical structures. The
initial structure was extracted from the experimentally determined
geometries obtained from the X-ray crystallographic data. Then, a
hundred of singlet and six triplet excited states were calculated by the
TD-DFT method37 at the PBE1PBE level based on the optimized gas-
phase structures. In the calculations of excited states, the conductor-
like polarizable continuum model method (CPCM)38 considering the
solvent effects of CH2Cl2 was employed. To compare the electronic
structures of complexes 5·2CH2Cl2·2H2O and 5(py)2·2py, the crystal
structures without further geometrical optimization were used for
excited-state calculations. The Pt−M interactions were also estimated
by the Mayer bond order.39 In these calculations, the Lanl2dz effective
core potential was used to describe the inner electrons of Pt, Ag, and P
atoms,40 while the associated double-ζ basis set of Hay and Wadt was
employed for the remaining outer electrons. Other nonmetal atoms of
C, H, O, and N were described by all-electron basis set of 6-
31G(p,d).41 To precisely describe the electronic properties, one
additional f-type polarization function was used for Pt (αf = 0.18) and
Ag (αf = 0.22) atoms, and an extra d-type polarization function was
added in P (αd = 0.34) atoms.42
1
ν/cm−1: 2082w (CC), 1096s (ClO4). H NMR (DMSO) δ/ppm:
8.34−8.23 (m, 3H), 8.20−8.05 (m, 7H), 8.02−7.80 (m, 8H), 7.70−
7.55 (m, 15H), 7.52−7.34 (m, 12H), 7.31−7.12 (m,17H), 6.88−
6.80(t, 4H, J = 7.6 Hz), 6.75−6.67 (m, 2H), 4.70−4.46 (m, 4H),
3.89−3.71 (m, 4H). 31P NMR (DMSO) δ/ppm: 16.28(m, 1P, JPt−P
=
2530 Hz, JP−P = 41.7 Hz), −5.00 (m, 2P, JAg−P = 493 Hz, JP−P = 42.0
Hz).
Physical Measurements. UV−vis absorption spectra were
measured on a Perkin-Elmer Lambda 25 UV−vis spectrophotometer.
Infrared spectra (IR) were recorded on a Magna 750 FT-IR
spectrophotometer with KBr pellets. Elemental analysis (C, H, N)
were carried out on a Perkin-Elmer model 240 C elemental analyzer.
Electrospray ionization mass spectrometry (ESI-MS) was performed
on a Finnigan LCQ mass spectrometer using dichloromethane and
1
methanol mixtures as mobile phases. H and 31P NMR spectra were
recorded on a Bruker Avance III 400 spectrometer with SiMe4 and
H3PO4 as internal and external references, respectively. Emission and
excitation spectra were recorded on a Perkin-Elmer LS55 lumines-
cence spectrometer with a red-sensitive photomultiplier type R928.
Emission lifetimes in solid states and degassed solutions were
determined on an Edinburgh analytical instrument (F900 fluorescence
spectrometer). The emission quantum yield (Φem) in degassed
dichloromethane solution at room temperature was calculated by Φs
= Φr(Br/Bs)(ns/nr)2(Ds/Dr) using [Ru(bpy)3](PF6)2 in acetonitrile as
the standard (Φem = 0.062) for the samples,32 where the subscripts r
and s denote reference standard and the sample solution, respectively,
and n, D, and Φ are the refractive index of the solvents, the integrated
intensity, and the luminscence quantum yield, respectively. The
quantity B is calculated by B = 1−10−AL, where A is the absorbance at
the excitation wavelength and L is the optical path length. Solid-state
quantum yields of powder samples in sealed quartz cuvettes were
determined by the integrating sphere using a SHIMADZU RF-
5301PC spectrofluorophotometer. To probe selectivity and reversi-
bility of the vapochromic properties to specific solvents, concentrated
CH2Cl2 solutions were put on quartz disks which were purged with N2
to dry. Luminescence vapochromic experiments were performed upon
sufficient exposure of the quartz disks or crystals to various saturated
vapors at ambient temperature for 10−15 min. A rapid vapochromic
response is usually observed in dozens of seconds to several minutes
depending on sample thickness in quartz disks or size of the crystals.
The PMMA films were made on quartz slides (2.5 cm × 4 cm) using
spin coating method, in which the solution was prepared by dissolving
complex 9 (10 mg) and PMMA (polymethylmethacrylate, 40 mg) in
dichloromethane (2 mL).
Crystal Structural Determination. Crystals suitable for X-ray
crystallographic measurement were grown by layering diethyl ether, n-
hexane, or n-heptane onto corresponding solutions with coordination
or/and crystal solvents, respectively, including 1·2CH2Cl2, 2·CH2Cl2,
4·4CH2Cl2, 4(MeCN)·MeCN, 5·2CH2Cl2·2H2O, 5(py)2·2py, 9·2ace-
tone, 9(DMF)2·2DMF, 9(MeCN)2·2Et2O, and 9(py)2·2py. Data
collection was performed on Mercury CCD diffractometer by the ω
scan technique at room temperature using graphite-monochromated
Mo−Kα (λ = 0.71073 Å) radiation. The CrystalClear software package
was used for data reduction and empirical absorption correction. The
structures were solved by direct methods. The heavy atoms were
located from E-map, and the rest of the non-hydrogen atoms were
found in subsequent Fourier maps. All non-hydrogen atoms were
refined anisotropically, while the hydrogen atoms were generated
geometrically and refined with isotropic thermal parameters. The
structures were refined on F2 by full-matrix least-squares methods
using the SHELXTL-97 program package.33 For 1·2CH2Cl2 and
2·CH2Cl2, the solvate molecules were treated as a diffuse contribution
to the overall scattering without specific atom positions by
ASSOCIATED CONTENT
* Supporting Information
■
S
Tables and figures giving additional photophysical and
computational results, and X-ray crystallographic files in CIF
format for the determination of 10 structures. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: czn@fjirsm.ac.cn.
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We are grateful for financial support from the NSFC
(20931006, U0934003, and 91122006) and the NSF of Fujian
Province (2011J01065).
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