Synthesis and luminescence of new Cu(I) complexes containing a binap ligand and a diimine ligand

Article abstract of DOI:10.1246/bcsj.79.437

A series of novel Cu(I) complexes with an s-binap ligand and a diimine ligand, [Cu(s-binap)(bpy)]PF₆, [Cu-(s-binap)(phen)]PF₆, and [Cu(s-binap)(dmp)]PF₆, were synthesized, where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10- phenanthroline, and s-binap = (S)-2,2′-bis(diphenylphosphino)-1,1′- binaphthyl. All three complexes show intense photoluminescence in the solid state, whereas [Cu(s-binap)(dmp)]PF₆ is a comparatively good emitter in CH₂Cl₂ solutions. These luminescence bands have been assigned to the emission from ³MLCT states. The complexes [Cu(s-binap)(bpy)]PF₆ and [Cu(s-binap)(dmp)]PF₆ were characterized by X-ray structure analyses. Although the distorted tetrahedral structures around the central metals of the two complexes are similar, the photophysical properties of the dmp complex differ from those of the other complexes in solution. The structures and the photophysical properties of the three complexes have been discussed.

Full text of DOI:10.1246/bcsj.79.437

Ó 2006 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 79, No. 3, 437–441 (2006)
437
Synthesis and Luminescence of New Cu(I) Complexes
Containing a Binap Ligand and a Diimine Ligand
ꢀ
Ken Saito, Toshiaki Tsukuda, and Taro Tsubomura
Department of Applied Chemistry, Seikei University, Kichijoji-Kitamachi, Musashino, Tokyo 180-8633
Received May 20, 2005; E-mail: tsubomura@st.seikei.ac.jp
A series of novel Cu(I) complexes with an s-binap ligand and a diimine ligand, [Cu(s-binap)(bpy)]PF6, [Cu-
(s-binap)(phen)]PF6, and [Cu(s-binap)(dmp)]PF6, were synthesized, where bpy = 2,20-bipyridine, phen = 1,10-phenan-
throline, dmp = 2,9-dimethyl-1,10-phenanthroline, and s-binap = (S)-2,20-bis(diphenylphosphino)-1,10-binaphthyl. All
three complexes show intense photoluminescence in the solid state, whereas [Cu(s-binap)(dmp)]PF6 is a comparatively
3
good emitter in CH2Cl2 solutions. These luminescence bands have been assigned to the emission from MLCT states.
The complexes [Cu(s-binap)(bpy)]PF6 and [Cu(s-binap)(dmp)]PF6 were characterized by X-ray structure analyses. Al-
though the distorted tetrahedral structures around the central metals of the two complexes are similar, the photophysical
properties of the dmp complex differ from those of the other complexes in solution. The structures and the photophysical
properties of the three complexes have been discussed.
(ꢁ)binap (0.62 g, 1 mmol) were dissolved in CH2Cl2 (15 mL).
After stirring for 90 min at room temperature, the addition of di-
ethyl ether to the solution of the complex gave a yellow powder
of the mixed-ligand complex, [Cu(binap)(dmp)]PF6. The complex
was obtained by filtration, and dried in vacuo. Anal. Calcd for
There has been increasing interest in the photophysics and
photochemistry of Cu(I) complexes in the last few decades.1–3
Mixed-ligand Cu(I) complexes containing diimine and diphos-
phine ligands represent an attractive class of compounds. We
have been studying the synthesis and emissive properties of
the mixed-ligand complexes, and found that the use of diphos-
phine chelates leads to the stabilization of the mixed-ligand
compounds. Recently, McMillin and co-workers synthesized
a Cu(I) complex with a diphosphine ligand, DPEphos (=bis[2-
(diphenylphosphino)phenyl] ether). The complex shows strong
luminescence and has a very long excited-state lifetime.4 It
suggests that using other diphosphine chelates is also effective
to make strongly emissive compounds.
C59H46CuF6Cl2N2P3 ([Cu(binap)(dmp)]PF6 CH2Cl2): C, 63.03;
H, 4.12; N, 2.49%. Found: C, 63.34; H, 3.73; N, 2.95%.
ꢂ
Other mixed-ligand complexes were prepared from [Cu-
(MeCN)4]PF6, diimine and diphosphine in CH2Cl2 in a similar
manner to that described above, where phen (1,10-phenanthroline)
and bpy (2,20-bipyridine) were used as diimine ligands.
[Cu(binap)(bpy)]PF6: Anal. Calcd for C54H40CuF6N2P3: C,
65.69; H, 4.08; N, 2.84%. Found: C, 65.34; H, 4.10; N, 2.65%.
[Cu(binap)(phen)]PF6: Anal. Calcd for C56H42CuF6N2P3O
We reported that the complex [Pt(s-binap)2] (s-binap = (S)-
2,20-bis(diphenylphosphino)-1,10-binaphthyl) shows interest-
ing photochemical and photophysical properties. The lumi-
([Cu(binap)(phen)]PF6 H2O): C, 65.34; H, 4.11; N, 2.72%.
Found: C, 65.53; H, 4.03; N, 2.73%.
ꢂ
Spectroscopic Measurement. The spectroscopic properties of
the mixed-ligand complexes in the CH2Cl2 solution were mea-
sured using a quartz cell connected to a glass tube and a Teflon
stop-cock. All samples were thoroughly deoxygenated by succes-
sive freeze–pump–thaw cycles. Absorption and luminescence
spectra were measured with a Shimadzu UV-2100 spectrophotom-
eter and a Shimadzu RF-5000 fluorometer, respectively. Lumines-
cence decay-curves were measured on a laboratory-made appa-
ratus; the sample was excited using a nitrogen laser (USHO
AN-200) and the emission light was focused into a Jobin-Yvon
H-20 monochromator equipped with a Hamamatsu R955 photo-
multiplier. The output of the photomultiplier was digitized by a
HP 54510 digital oscilloscope and then downloaded to a PC.
Emission quantum yields, ꢀ, were measured in a deaerated
(freeze–pump–thaw cycles) CH2Cl2 solution at 20 ꢃ 1 ꢄC with the
use of [Ru(bpy)3](PF6)2 in CH3CN as a standard (ꢀ ¼ 0:09).7 The
emission spectra were corrected with a calibration function that
was made with the use of N,N0-dimethyl-3-nitroaniline and 4-
dimethylamino-40-nitrostylbene as standard substances.9
ꢀ
nescent MLCT state based on the low-energy ꢀ orbitals of
s-binap is characteristic of the [Pt(s-binap)2] complex.5–7 Since
Cu(I) has the same d10 electronic arrangement as Pt(0), the
photophysics of Cu(I) complexes containing an s-binap ligand
are interesting.
We report here the synthesis and photophysical properties of
three mixed-ligand Cu(I) complexes, [Cu(s-binap)(diimine)]þ.
We use the term ‘‘diimine’’ to represent the ligands, bpy, phen,
and dmp. In this paper, s-binap is used as the diphosphine li-
gand, which is abbreviated as binap.
Experimental
Materials. The preparation of the mixed-ligand complexes
was conducted under an Ar atmosphere using standard Schlenk
tube techniques. All reagents were obtained from commercial sup-
pliers and used without further purification. The starting material,
[Cu(MeCN)4]PF6, was prepared according to the published meth-
od.8
[Cu(binap)(dmp)]PF6. [Cu(MeCN)4]PF6 (0.37 g, 1 mmol),
dmp (2,9-dimethyl-1,10-phenanthroline) (0.22 g, 1 mmol), and (S)-
Data Collection and Reduction for X-ray Crystallographic
Analyses of [Cu(binap)(bpy)]PF6 and [Cu(binap)(dmp)]PF
6Á
Published on the web March 8, 2006; DOI 10.1246/bcsj.79.437

438 Bull. Chem. Soc. Jpn. Vol. 79, No. 3 (2006)
Synthesis and Properties of Cu(I) Complexes
C4H10O. Data were collected on an automated Rigaku AFC5S
diffractometer using graphite-monochromated Mo Kꢁ radiation
ꢄ
ꢁ
C 36
C 1
(ꢂ ¼ 0:71069 A) at 23 C. Three standard reflections were mea-
sured in every 150 reflections. An empirical absorption correction
based on azimuthal scans of several reflections was applied. Cal-
culations were carried out by using teXsan.10 The single crystals
for X-ray structural analysis were obtained by slow diffusion of
hexane or ether for the bpy and dmp complexes, respectively, into
the CH2Cl2 solution of the complexes. Crystallographic data have
been deposited with Cambridge Crystallographic Data Centre:
Deposition numbers CCDC-282440 for [Cu(binap)(bpy)]PF6,
CCDC-282439 for [Cu(binap)(dmp)]PF6. Copies of the data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge, CB2 1EZ, UK; Fax: +44
1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
P 1
Cu 1
N 2
N 1
C 23
P 2
C 108
C 109
ꢁ
Crystal Data of [Cu(binap)(bpy)]PF6: a ¼ 16:461ð3Þ A, b ¼
ꢄ
ꢁ
ꢁ
ꢁ 3
15:142ð5Þ A, c ¼ 22:371ð3Þ A, ꢃ ¼ 107:40ð1Þ , V ¼ 5320ð1Þ A ,
space group = P21 (#4), Z ¼ 4, Dcalcd ¼ 1:250 g cmꢁ3, ! ꢁ 2ꢄ
scan method, No. of collected reflections = 16059, No. of unique
reflections (2ꢄ < 50:0ꢄ) = 9741, R1 ¼ 0:078 (I > 2ꢅðIÞ), wR2 ¼
0:224 (all data), GOF ¼ 1:044, ꢆ ¼ 1:11 mmꢁ1, highest peak and
deepest hole in the last difference Fourier map were 0.66 and
C 64
C 66
N 4
N 3
P 4
Cu 2
P 3
C 98
ꢁ ꢁ3
ꢁ0:42 e A , respectively.
Crystal Data of [Cu(binap)(dmp)]PF C H O:
10
a ¼
ꢁ 3
6Á
4
C 55
ꢁ
ꢁ
ꢁ
11:944ð1Þ A, b ¼ 40:749ð1Þ A, c ¼ 10:561ð1Þ A, V ¼ 5140ð7Þ A ,
space group = P212121 (#19), Z ¼ 4, Dcalcd ¼ 1:343 g cmꢁ3, !
scan method, No. of collected reflections = 5554, No. of unique
reflection (2ꢄ < 60:0ꢄ) = 5509, R1 ¼ 0:0803 (I > 2ꢅðIÞ), wR2 ¼
0:2425 (all data), GOF ¼ 0:975, ꢆ ¼ 0:58 mmꢁ1, highest peak
and deepest hole in the last difference Fourier map were 0.64
Fig. 1. Molecular structure of [Cu(binap)(bpy)]PF6 (the
counter ion and hydrogen atoms are omitted). Two crys-
tallographically independent ꢄcations are shown. Selected
ꢁ
bond lengths (A) and angles ( ): Cu1–P1 = 2.272(4), Cu1–
P2 = 2.258(5), Cu1–N1 = 2.07(1), Cu1–N2 = 2.09(1),
Cu2–P3 = 2.241(4), Cu2–P4 = 2.232(5), Cu2–N3 =
2.05(1), Cu2–N4 = 2.03(2); P1–Cu1–P2 = 101.9(2), N1–
Cu1–N2 = 80.0(6), P3–Cu2–P4 = 103.2(2), N3–Cu2–
N4 = 79.5(5).
ꢁ ꢁ3
and ꢁ0:42 e A , respectively.
Structure Determination of [Cu(binap)(bpy)]PF6 and [Cu-
(binap)(dmp)]PF6. The structures were solved by a direct meth-
od and refined by full-matrix least-squares methods.11 Hydrogen
atoms were placed at the idealized positions, and the coordinates
and the isotropic temperature factors were fixed. Anisotropic tem-
perature factors were used for all non-hydrogen atoms except for
the atoms shown below. The structure of [Cu(binap)(bpy)]PF6
showed disorder in a phenyl group (C103–108 and C109–114).
The phenyl carbon atoms were treated as rigid bodies. The occu-
pancy ratio for both disordered phenyl groups was 50/50.
Crystal Structure Analysis of [Cu(binap)(dmp)]PF6.
The structure is similar to that of [Cu(binap)(bpy)]PF6. An
asymmetric unit of the crystal of the compleꢁx consists of one
[Cu(binap)(dmp)]þ cation (Fig. 2), one PF6 anion and one
ꢁ
ether molecule. The Cu–P distances (2.292(4) and 2.290(4) A)
are slightly longer than those of [Cu(binap)(bpy)]þ, but com-
parable to those found in other Cu(I) complexes containing
P, P chelate ligands, and the Cu–N distances (2.10(1) and
Results and Discussion
Crystal Structure Analysis of [Cu(binap)(bpy)]PF6. The
crystal of the complex consists of two [Cu(binap)(bpy)]þ cat-
ions (Fig. 1) and two PF6 anions in an asymmetric unit. The
structures of the two complex ions are similar to each other.
The coordination geometry of each of the Cu(I) atoms is best
described as a distorted tetrahedron. The Cu–P distances
ꢁ
2.09(1) A) compare well with other Cu(I) complexes contain-
ing diimine chelate ligands.3,4,12–15 The P–Cu–P angles of
the binap chelate and the N–Cu–N angles of the dmp chelate
are 100.6(1) and 80.8(6)ꢄ, respectively. Other geometrical
parameters around the Cu(I) atoms are listed in the caption
of Fig. 2.
ꢁ
(2.241(4), 2.232(5), 2.272(4), and 2.258(5) A) are comparable
to those found in other Cu(I) complexes containing diphos-
phine chelate ligands.12,13 The Cu–N distances (2.07(1),
The non-bonding interactions are listed in Table 1. The
ꢁ
table shows non-bonding C–C distances shorter than 3.90 A.
ꢁ
2.09(1), 2.05(1), and 2.03(2) A) are also similar to other
The carbon atoms C13 and C14 in the methyl group of dmp
are close to some carbon atoms of the binap ligand. It is clear
that the structure of [Cu(binap)(dmp)]þ is more crowded
around the copper atom of than [Cu(binap)(bpy)]þ. The long
Cu–P distances in [Cu(binap)(dmp)]þ compared with those
in [Cu(binap)(bpy)]þ may reflect the interaction.
Cu(I) complexes containing diimine chelate ligands.3,4,12,14,15
The two P–Cu–P angles of the binap chelate and the two N–
Cu–N angles of the bpy chelate are (101.9(2) and 103.2(2)ꢄ)
and (80.0(6) and 79.5(5)ꢄ), respectively. These values are typi-
cal for Cu(I) complexes containing diphosphine and/or di-
imine chelate ligand(s).3,4,12–15 Other geometrical parameters
around the Cu(I) atoms are listed in the caption of Fig. 1.
Photophysical Properties. The UV spectra of the CH2Cl2
solution containing the [Cu(binap)(diimine)]þ complexes are

K. Saito et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 3 (2006)
439
1 104
8000
6000
4000
2000
0
C 16
a)
b)
c)
d)
C 13
P 1
N 1
Cu
C 58
C 14
C 48
ε
P 2
N 2
C 42
C 47
C 33
300
350
400
450
500
550
600
Fig. 2. Molecular structure of [Cu(binap)(dmp)]PF6 (the
counter ion and hydrogen atoms are omitted). Selected
Wavelength / nm
Fig. 3. Room-temperature electronic absorption spectra of
a) = [Cu(binap)(bpy)]PF6, b) = [Cu(binap)(phen)]PF6,
c) = [Cu(dmp)2]PF6, and d) = [Cu(binap)(dmp)]PF6.
These spectra are measured in degassed CH2Cl2.
ꢄ
ꢁ
bond lengths (A) and angles ( ): Cu–P1 = 2.292(4), Cu–
P2 = 2.290(4), Cu–N1 = 2.10(1), Cu–N2 = 2.09(1); P1–
Cu–P2 = 100.6(1), N1–Cu–N2 = 80.8(6).
Table 1. Intramolecular Non-Bonding C–C DistancesaÞ
served in the region 350–450 nm, which are also assigned to
the MLCT transitions.
Complex
The real species of the mixed-ligand complexes present in a
CH2Cl2 solution would not be simple, because Cu(I) is known
to be labile in the solution. Since CH2Cl2 cannot act as a
ligand, simple ligand dissociation, i.e. substitution with a sol-
vent molecule, seems unlikely. Therefore, the following dis-
proportionation is the most probable reaction:
[Cu(binap)(bpy)]PF6
[Cu(binap)(dmp)]PF6
ꢁ
Distance/A
ꢁ
Distance/A
Atoms
Atoms
C1–C36
C1–C23
C55–C98
C64–C108
C64–C66
C64–C109
3.35(3)
3.58(3)
3.69(3)
3.51(3)
3.55(3)
3.87(4)
C13–C36
C13–C16
C13–C35
C13–C58
C14–C33
C14–C42
C14–C48
C14–C47
3.39(3)
3.56(3)
3.57(3)
3.65(3)
3.46(3)
3.61(2)
3.82(2)
3.86(3)
2[Cu(binap)(diimine)]þ
ꢀ [Cu(diimine)2]þ þ [Cu(binap)2]þ:
ð1Þ
The formation of binuclear complexes is another possibility
as shown in the other diphosphine complexes,15,16 but binap is
not likely to act as a bridging ligand. If the above disproportio-
nation reaction occurs, an absorption band of [Cu(diimine)2]þ
should be observed in the 450 nm region. However, the absorp-
tion spectra of the complexes all show very low absorption
intensities at 450 nm. Therefore, the concentration of [Cu-
(diimine)2]þ should be significantly low when compared with
that of the mixed-ligand complex. On the basis of the above
consideration, we concluded that the major species present in
each solution was the mononuclear mixed-ligand complex,
[Cu(binap)(diimine)]þ.
a) Intramolecular non-bonding C–C distances shorter than
ꢁ
3.9 A. The carbons shown in left of hyphen are those con-
tained in the diimine ligand, and those shown in right of
hyphen are contained in the binap ligand. C13 and C14 are
the carbons of the methyl group in dmp.
presented in Fig. 3. A distinct absorption band at 393 nm with
a small shoulder at 457 nm is found for [Cu(binap)(dmp)]þ.
The absorption bands of [Cu(diimine)2]þ were extensively
studied, and they are typically observed at 440–460 nm ([Cu-
(phen)2]þ, 440 nm; [Cu(dmp)2]þ, 457 nm; and [Cu(tmbp)2]þ,
454 nm (tmbp = 4,40,6,60-tetramethyl-2,20-bipyridine)). The
The emission spectra of the solid-state [Cu(binap)(di-
imine)]PF6 are presented in Fig. 4. In the solid state, all three
complexes, [Cu(binap)(dmp)]PF6, [Cu(binap)(bpy)]PF6, and
[Cu(binap)(phen)]PF6, are strong emitters. The bpy and phen
complexes exhibit a slightly higher intensity in the emission
bands than the dmp complex. The emission maxima of the
three complexes are 558, 594, and 572 nm, respectively.
Since the energies of the emission bands are comparable to
those of [Cu(dmp)(PPh3)2]þ (560 nm) and [Cu(dmp)(dppe)]þ
(630 nm),3 and the emissive states of the latter two complexes
were assigned to 3MLCT, the emission of the binap complexes
ꢀ
bands have been assigned as MLCT (Cu(d) ! diimine(ꢀ ))
transitions. It has been reported that substitution of the diimine
chelate by a phosphine ligand causes a blue shift of the MLCT
band: e.g., 365 nm for [Cu(phen)(PPh3)2]þ, 383 nm for
[Cu(dmp)(DPEphos)]þ, and 400 nm for [Cu(dmp)(dppe)]þ
(dppe = 1,2-bis(diphenylphosphino)ethane).3 The absorption
maximum of [Cu(binap)(dmp)]þ (393 nm) is blue-shifted from
that of [Cu(dmp)2]þ, and the intensity of the band (" ¼ 5200
M
ꢁ1 cmꢁ1) is similar to those of the [Cu(diimine)2]þ com-
plexes. Therefore, the absorption band presented at 393 nm
is characterized as MLCT involving the ꢀ orbital of the
ꢀ
3
should originate from the MLCT states.
dmp ligand of the mixed-ligand complex. For the complexes
[Cu(binap)(bpy)]þ and [Cu(binap)(phen)]þ, absorption bands
of moderate intensities (" ¼ 3000{5000 Mꢁ1 cmꢁ1) are ob-
The emission spectra of the CH2Cl2 solutions containing the
[Cu(binap)(dmp)]þ complexes (1 ꢅ 10ꢁ5 M) and [Cu(binap)-
(bpy)]þ complexes (1 ꢅ 10ꢁ4 M) are presented in Fig. 5. In

440 Bull. Chem. Soc. Jpn. Vol. 79, No. 3 (2006)
Synthesis and Properties of Cu(I) Complexes
nm) is assigned to the MLCT band of the mixed-ligand com-
plex. In addition to the 670 nm band, there is an additional
band at 467 nm. The emission maximum of [Cu(binap)(bpy)]þ
in the solution state is red-shifted from that of the [Cu(binap)-
(dmp)]þ, which is similar to that of the solid state. The high-
a)
b)
c)
ꢀ
energy emission is assigned to the ꢀ–ꢀ transition of the
binap ligand.17 These data show that some amounts of [Cu-
(binap)2]þ and/or free binap should be present in the solution
of [Cu(binap)(bpy)]þ, although the dominate species must be
the mixed-ligand complex, which has already been discussed
above. Since the absorption intensity of the solution of [Cu-
(binap)(dmp)]þ at 460 nm is not 0, existence of the binap li-
gand or [Cu(binap)2]þ is also suggested in the solution. How-
ever, the MLCT emission of the mixed-ligand complex, [Cu-
(binap)(dmp)]þ, is dominant in the luminescence spectra of
the solution.
450
500
550
600
650
700
750
800
Wavelength / nm
The spectrum of the MLCT luminescence in the solution of
[Cu(binap)(phen)]þ, which is not shown in the figure, consists
of bands similar to those observed for [Cu(binap)(bpy)]þ, and
the intensities of the bands are also very weak. We could not
get reliable data on the quantum yields of the emission of
[Cu(binap)(bpy)]þ and [Cu(binap)(phen)]þ, because of 1)
low intensity of the emission and 2) presence of two emissive
species in the spectrum.
Fig. 4. Room-temperature solid-state emission spectra of
a) = [Cu(binap)(bpy)]PF6, b) = [Cu(binap)(phen)]PF6,
and c) = [Cu(binap)(dmp)]PF6 (ꢂex ¼ 310 nm).
a)
b)
The above results show that the MLCT emission is severely
quenched for the bpy and phen complexes in solution. This is
explained by a solvent-induced exciplex quenching. This
quenching mechanism, which involves a transient increase in
the coordination number of the copper center, is widely found
for the CT excited state of copper(I) complexes.18
An important feature of [Cu(binap)(dmp)]þ is that the di-
imine ligand has methyl groups at the 2,9-positions. The role
of the substituents on the luminescence properties of the com-
plexes has been discussed in detail.1,2,18 The methyl groups at
the 2,9-positions resist the structural distortion of the complex
in the excited state. At the same time, the steric bulkiness
around the metal-center becomes large because of the methyl
groups at the 2,9-positions, and prevent [Cu(binap)(dmp)]þ re-
actions with the solvent molecules. These effects should pre-
vent the [Cu(binap)(dmp)]þ complex from quenching of the
luminescence.
In this work, we synthesized a series of [Cu(binap)-
(diimine)]þ complexes, and an X-ray study clarified the steric
crowdedness of the [Cu(binap)(dmp)]þ complex. The dmp
complex only shows relatively intense emission in solution,
whereas all three complexes are good emitters in the solid
state. The steric crowdedness of the dmp complex should also
contribute to the photophysical properties of [Cu(binap)-
(dmp)]þ.
450
500
550
600
650
700
750
800
Wavelength / nm
Fig. 5. Room-temperature solution-state emission spectra
of a) [Cu(binap)(dmp)]þ (1 ꢅ 10ꢁ5 M) and b) [Cu(binap)-
(bpy)]þ (1 ꢅ 10ꢁ4 M) measured in degassed CH2Cl2
(ꢂex ¼ 370 nm).
contrast to the solid-state spectra, the three complexes show
completely different luminescence. [Cu(binap)(dmp)]þ has a
comparatively strong emission band centered at 613 nm. The
emission maximum of [Cu(binap)(dmp)]þ in the solution state
is red-shifted ca. 50 nm from that of the solid state, and the band
is blue-shifted from that of [Cu(dmp)2]þ. The quantum yield
(ꢀ) of luminescence of [Cu(binap)(dmp)]þ is 1:0 ꢃ 0:2% in
the CH2Cl2 solution; the value is the same as the reported val-
ue for [Cu(dmp)(dppe)]þ.4 The quantum yield is much larger
than that of [Cu(dmp)(PPh3)2]þ. A single exponential decay
(ꢇ ¼ 600 ns) was observed for [Cu(binap)(dmp)]þ. The value
indicates that the MLCT state has a triplet character.
The intensity of the luminescence of [Cu(binap)(bpy)]þ and
[Cu(binap)(phen)]þ in a CH2Cl2 solution is very low when
the concentrations of the complexes are low (1 ꢅ 10ꢁ5 M).
In Fig. 5, we show the luminescence spectrum of the solution
containing [Cu(binap)(bpy)]þ in high concentration (1 ꢅ 10ꢁ4
M). The luminescence spectrum of the solution of [Cu(binap)-
(bpy)]þ consists of two bands. The low-intensity band (670
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