Synthesis, structures and photophysical properties of luminescent copper(i) and platinum(ii) complexes with a flexible naphthyridine-phosphine ligand

Article abstract of DOI:10.1039/b717777a

Condensation of Ph₂PH and paraformaldehyde with 2-amino-7-methyl-1,8-naphthyridine gave the new flexible tridentate ligand 2-[N-(diphenylphosphino)methyl]amino-7-methyl-1,8-naphthyridine (L). Reaction of L with [Cu(CH₃CN)₄]BF₄ and/or different ancillary ligands in dichloromethane afforded N,P chelating or bridging luminescent complexes [(L)₂Cu₂](BF₄) ₂, [(μ-L)₂Cu₂(PPh₃) ₂](BF₄)₂ and [(L)Cu(CNN)]BF₄ (CNN = 6-phenyl-2,2′-bipyridine), respectively. Complexes [(L) ₂Pt]Cl₂, [(L)₂Pt](ClO₄)₂ and [(L)Pt(CNC)]Cl (CNC = 2,6-biphenylpyridine) were obtained from the reactions of Pt(SMe₂)₂Cl₂ or (CNC)Pt(DMSO)Cl with L. The crystal structures and photophysical properties of the complexes are presented. The Royal Society of Chemistry 2008.

Full text of DOI:10.1039/b717777a

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www.rsc.org/dalton | Dalton Transactions
Synthesis, structures and photophysical properties of luminescent copper(I)
and platinum(II) complexes with a flexible naphthyridine-phosphine ligand†
Jun-Feng Zhang,a,b Wen-Fu Fu,*a,b Xin Ganb and Jian-Hua Chenb
Received 16th November 2007, Accepted 20th March 2008
First published as an Advance Article on the web 30th April 2008
DOI: 10.1039/b717777a
Condensation of Ph2PH and paraformaldehyde with 2-amino-7-methyl-1,8-naphthyridine gave the new
flexible tridentate ligand 2-[N-(diphenylphosphino)methyl]amino-7-methyl-1,8-naphthyridine (L).
Reaction of L with [Cu(CH3CN)4]BF4 and/or different ancillary ligands in dichloromethane afforded
N,P chelating or bridging luminescent complexes [(L)2Cu2](BF4)2, [(l-L)2Cu2(PPh3)2](BF4)2 and
[(L)Cu(CNN)]BF4 (CNN = 6-phenyl-2,2ꢀ-bipyridine), respectively. Complexes [(L)2Pt]Cl2,
[(L)2Pt](ClO4)2 and [(L)Pt(CNC)]Cl (CNC = 2,6-biphenylpyridine) were obtained from the reactions of
Pt(SMe2)2Cl2 or (CNC)Pt(DMSO)Cl with L. The crystal structures and photophysical properties of the
complexes are presented.
^
Reports on a P N chelate for rigid ligands are rather scarce. The
Introduction
structures with four-membered chelate rings were only achieved
in some metal complexes by coordination of the 2-(diphenyl-
phosphino)pyridine ligand to Rh(II),19 Fe(II),20 W(I)21 and
Rh(III),22 whereas the chelated Pd(II) complexes using new flex-
ible P,N pyridylphosphine ligands were recently reported by
Long and co-workers.23 We have focussed on development of a
new series of flexible pyrimidine- and naphthyridine-phosphine
ligands and their complexes.24 Herein we report on the syn-
thesis, structures and photophysical properties of the copper(I)
and platinum(II) complexes with a new flexible 2-[N-(diphenyl-
phosphino)methyl]amino-7-methyl-1,8-naphthyridine (L) ligand
(Scheme 1), [(L)2Cu2](BF4)2 (1), [(l-L)2Cu2(PPh3)2](BF4)2 (2),
[(L)Cu(CNN)]BF4 (3) (CNN = 6-phenyl-2,2ꢀ-bipyridine), [(L)2-
Pt]Cl2 (4), [(L)2Pt](ClO4)2 (5) and [(L)Pt(CNC)]Cl (6) (CNC =
2,6-biphenylpyridine). To the best of our knowledge, there are no
reports of such work based on a flexible naphthyridine-phosphine
ligand.
The intriguing structures and bonding properties of 1,8-
naphthyridine derivative complexes, as well as the spectroscopic
properties1–4 associated with this class of compounds, have gener-
ated many studies focused on the chemistry of the naphthyridine
metal complexes.5–11 In particular, the diphenylphosphino-
1,8-naphthyridine ligand12,13 and its derivatives14 (Scheme 1),
which can be regarded as a combination of the bidentate
1,8-naphthyridine (hard Lewis base) and 2-(diphenylphosphino)
pyridine (soft Lewis base), exhibit various coordination modes
and interesting spectroscopic properties. The complexes of
Cu(I),15 Ag(I),16 Au(I),17 Pt(II) and Pd(II)18 with 1,8-naphthyridine
derivatives containing a phosphorus atom and a chelating
aromatic N-donor display a variety of geometries. The ligands
^
^
I and II in Scheme 1 usually exhibit bridging P N or P P
^
coordination modes instead of P N chelating ones, which can
be ascribed to the limitation of their rigid structural frameworks.
Results and discussion
The flexible new ligand L was easily prepared by the reaction
of 2-methyl-7-amino-1,8-naphthyridine with Ph2PH and (CH2O)n
refluxing in toluene under a nitrogen atmosphere, according
to a previously developed method (Mannich reaction).25 The
condensed ligand L was isolated with a good yield as a white
solid, and was freely soluble in CH2Cl2 and CHCl3, but had
moderate and poor solubility in MeOH and Et2O, respectively. The
preparation procedures of the L ligand and its complexes 1–6 are
shown in Scheme 2. (i) HPPh2/(CH2O)n; (ii) [Cu(CH3CN)4]BF4;
(iii) [Cu(CH3CN)4]BF4/PPh3; (iv) [Cu(CH3CN)4]BF4/CNN; (v)
Pt(SMe2)2Cl2; (vi) K2PtCl4/LiClO4; (vii) (CNC)Pt(DMSO)Cl.
Scheme 1
aLaboratory Of Organic Optoelectronic Functional Materials and Molecular
Engineering, Technical Institute of Physics and Chemistry, Chinese Academy
of Sciences, Beijing, 100080, P. R. China
Crystal structures
All of the complexes reported here are air-stable and have been
structurally characterized by X-ray crystal analysis. Selected
bond lengths and angles are listed in Table 1. Reaction of L
with [Cu(CH3CN)4]BF4 in dichloromethane yielded the binuclear
bCollege of Chemistry and Chemical Engineering, Yunnan Normal Univer-
sity, Kunming, 650092, P. R. China. E-mail: wf_fu@yahoo.com.cn
† CCDC reference numbers 666202–666207. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b717777a
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Scheme 2 Synthesis of 1–6.
copper(I) complex 1. In contrast to the linear trinuclear copper(I)
complex15 with rigid diphenylphosphino-naphthyridine ligands,
the complex cation of 1 comprises a dicopper center wrapped
around by two L ligands displaying P,N(2)-chelating and P,N(1)-
bridging coordination modes (Fig. 1). Each copper(I) atom is
coordinated by two nitrogen atoms from two L ligands and
one phosphorus atom from the phosphine group, finishing its
T-shaped CuN2P geometry at the Cu atoms. The copper(I)
˚
the Cu(1)–P(1) distance is 2.177(3) A. These coordinated N(2)
and P(1) atoms in the chelating ring are all afforded by another
L ligand. Corresponding N(1A)–Cu(1)–P(1), N(1A)–Cu(1)–N(2)
and P(1)–Cu(1)–N(2) bond angles are 155.2(3), 104.6(3) and
94.2(2)◦, respectively. The intramolecular Cu(1) · · · Cu(2) distance
˚
is 2.908(3) A. These data are all comparable to those observed
for other Cu(I) analogues,11 and also confirm the distorted planar
trigonal coordination geometry of the copper(I) center.
˚
to naphthyridine-N bond distance Cu(1)–N(1A) is 1.944(8) A,
Complex 2 was obtained as a yellow solid by reacting equimolar
[Cu(CH3CN)4]BF4, PPh3 and L under a nitrogen atmosphere
in dichloromethane solution. Unlike the chelating mode found
in the structure of complex 1, the crystal structure of 2 in-
dicates that ligand L bridges two Cu(I) metal centers through
the naphthyridine-N atoms and the phosphine group to form
a bimetallic sixteen-membered ring that can be divided into
two CuNCN four-membered rings and a twelve-membered ring
having a boat conformation (Fig. 2). Each copper atom has
a distorted tetrahedral geometry in which the metal center is
coordinated to two chelating naphthyridine-N atoms of one L
ligand and one phosphorus atom of another L ligand, leaving
the fourth coordinating point occupied by the independent PPh3.
The two tridentate L ligands bridge the two copper atoms in a
head-to-tail configuration. The average Cu–N and Cu–P bond
˚
shorter than the bond length for Cu(1)–N(2) of 2.287(8) A, and
˚
lengths are 2.159(4) and 2.256(2) A, respectively, similar to those
in [Cu2(dpnapy)3][ClO4]2 (dpnapy = 7-diphenylphosphino-2,4-
dimethyl-1,8-naphthyridine).15 The bond angles at the copper
atoms vary from 61.5(1) to 131.59(6)◦. The non-bonding Cu · · · Cu
˚
separation in this compound is 5.218 A, which is longer than that in
twelve-membered ring dipalladium complexes linked by nonrigid
˚
ligands phosphine-pyridine (4.594 A) and phosphine-pyrimidine
(4.921 A).24 The two naphthyridine (N1–C9–N2 and N4–C31–N5)
˚
Fig. 1 Perspective drawing (30% thermal ellipsoids) of the cation in
complex 1 on a crystallographic twofold axis with phenyl rings and the
hydrogen atoms removed for clarity.
planes are not parallel to each other showing a dihedral angle of
8.6◦.
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◦
˚
Table 1 Selected bond lengths (A) and angles ( ) for 1–6
Complex 1a
Cu(1)–N(1)#
Cu(1)–N(2)
N(1)–Cu(1)#
1.944(8)
2.287(8)
1.943(8)
Cu(1)–P(1)
Cu(1)–Cu(1)#
2.177(3)
2.908(3)
N(1)#–Cu(1)–P(1)
P(1)–Cu(1)–N(2)
P(1)–Cu(1)–Cu(1)# 120.0(9)
155.2(3)
94.2(2)
N(1)–Cu(1)–N(2)
N(1)#–Cu(1)–Cu(1)#
N(2)–Cu(1)–Cu(1)#
104.6(3)
82.6(2)
67.7(2)
Complex 2
Cu(1)–N(1)
Cu(1)–N(2)
Cu(2)–N(4)
Cu(2)–P(3)
2.179(4)
2.239(4)
2.053(4)
2.288(2)
Cu(1)–P(4)
Cu(1)–P(1)
Cu(2)–P(2)
2.218(1)
2.293(2)
2.223(1)
Fig. 2 Perspective drawing (30% thermal ellipsoids) of the cation in
complex 2 with the hydrogen atoms removed for clarity.
N(1)–Cu(1)–P(4)
P(4)–Cu(1)–N(2)
P(4)–Cu(1)–P(1)
N(4)–Cu(2)–P(2)
P(2)–Cu(2)–P(3)
125.9(1)
124.9(1)
126.3(5)
119.9(1)
131.6(6)
N(1)–Cu(1)–N(2)
N(1)–Cu(1)–P(1)
N(2)–Cu(1)–P(1)
N(4)–Cu(2)–P(3)
61.5(1)
100.4(1)
98.8(1)
106.9(1)
Complex 3
Cu(1)–N(2)
Cu(1)–P(1)
2.040(6)
2.162(2)
Cu(1)–N(1)
Cu(1)–N(3)
2.055(6)
2.205(5)
N(2)–Cu(1)–N(1)
N(1)–Cu(1)–P(1)
N(1)–Cu(1)–N(3)
80.4(3)
133.9(2)
117.2(2)
N(2)–Cu(1)–P(1)
N(2)–Cu(1)–N(3)
P(1)–Cu(1)–N(3)
130.0(2)
95.1(2)
96.2(2)
Complex 4
Pt(1)–N(4)
Pt(1)–P(2)
2.126(4)
2.204(2)
Pt(1)–N(1)
Pt(1)–P(1)
2.139(4)
2.209(2)
N(4)–Pt(1)–N(1)
N(1)–Pt(1)–P(2)
N(1)–Pt(1)–P(1)
92.5(2)
167.4(1)
83.9(1)
N(4)–Pt(1)–P(2)
N(4)–Pt(1)–P(1)
P(2)–Pt(1)–P(1)
83.5(1)
167.3(1)
102.5(8)
Complex 5
Pt(1)–N(4)
Pt(1)–P(1)
2.126(4)
2.202(2)
Pt(1)–N(1)
Pt(1)–P(2)
2.126(4)
2.213(2)
Fig. 3 Perspective drawing (30% thermal ellipsoids) of the cation in
complex 3 with the hydrogen atoms removed for clarity.
N(4)–Pt(1)–N(1)
N(1)–Pt(1)–P(1)
N(1)–Pt(1)–P(2)
90.6(2)
84.0(1)
166.0(1)
N(4)–Pt(1)–P(1)
N(4)–Pt(1)–P(2)
P(1)–Pt(1)–P(2)
166.5(1)
85.0(1)
103.06(7)
CN,N-chelating and P-coordinating, leaving free naphthyridine-
N atoms was unsuccessful. This indicated that the L ligand more
favorably adopts the P,N-chelating coordination and forms a
stable six-membered ring structure.
Complex 6
The copper atom in 3 is four-coordinated with a distorted
tetrahedral geometry in which the L ligand and the CNN ligand
chelate the metal center through P,N and N,N atoms, respectively.
Compared with the copper(I) to naphthyridine-N bond length
Pt(1)–C(1)
Pt(1)–N(3)
1.991(3)
2.183(3)
Pt(1)–N(1)
Pt(1)–P(1)
2.118(3)
2.1878(9)
C(1)–Pt(1)–N(1)
N(1)–Pt(1)–N(3)
N(1)–Pt(1)–P(1)
80.0(1)
99.7(1)
164.67(8)
C(1)–Pt(1)–N(3)
C(1)–Pt(1)–P(1)
N(3)–Pt(1)–P(1)
163.0(1)
101.6(1)
83.27(8)
˚
Cu(1)–N(3) of 2.205(5) A, the average bond distance of copper(I)
to nitrogen atoms of the CNN ligand is much shorter (2.048(6)
a Atoms marked with a # are related by C2 symmetry.
˚
˚
A). The bond length Cu–P of 2.162(2) A falls within the normal
ranges for copper phosphine complexes. The bond angles at the
copper atom vary from 80.4(3) to 133.6(2)◦.
When ligand L was reacted with [Cu(CH3CN)4]BF4 in a 1 :
1 molar ratio in the presence of an ancillary ligand 6-phenyl-
2,2ꢀ-bipyridine (CNN) in dichloromethane, the mononuclear
copper(I) complex 3 using P,N(3)- and CN,N-chelation was ob-
tained with a nathphyridine-N remaining uncoordinated to the Cu
center (Fig. 3). An attempt to prepare the [(CNN)Cu(L)2]BF4 via
A P-coordinated platinum(II) complex [Pt{Ph2PCH2N(H)-
C5H3(OH)N}2Cl2] obtained from the reaction of Ph2PCH2-
N(H)C5H3(OH)N and [PtCl2(cod)] (cod = cycloocta-1,5-diene)
in a 2 : 1 molar ratio has been reported by Smith and co-workers,26
in which the chloride atom had not been abstracted by the nitrogen
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atom of pyridine. However, in the present study, the reaction of L
and Pt(SMe2)2Cl2 in a 2 : 1 molar ratio in dichloromethane gave
only the complex cis-[(L)2Pt]Cl2·2CH2Cl2 (4·2CH2Cl2) with a high
yield (70%). The L ligand of 4 adopted the same coordinating
mode as that of 3, which further proved that L prefers the P,
N(1)-chelating mode.
Addition of an excess of LiClO4 to the solution of 4 in CH3CN
generated the complex [(L)2Pt](ClO4)2·CH2Cl2 (5·CH2Cl2). Com-
plex [(L)Pt(CNC)]Cl (6) was prepared following a procedure
similar to that described for 4, but using (CNC)Pt(DMSO)Cl
as a starting material, and in chloroform at room temperature.
Complexes 4 and 5 have similar crystal structures. The bis-chelate
dicationic complex has a near square-planar environment around
the Pt center and forms the cis isomer exclusively (Fig. 4 and 5).
The L ligand chelates the platinum center through the P atom
and the N(1)/N(4) atom of the naphthyridine group, and the
average bond lengths of Pt–P and Pt–N are 2.207(2) and 2.129(4)
˚
A, respectively. The N(2)/N(5) atom of the naphthyridine group
˚
is uncoordinated with an average Pt–N distance of 2.931 A. The
least-squares plane through the atoms Pt(1), P(1), P(2), N(1) and
˚
N(2) has a mean deviation of 0.17 A. The plane defined by Pt and
the coordinated P and N(3) atoms makes a dihedral angle of 15.5 ◦
Fig. 5 Perspective drawing (30% thermal ellipsoids) of the complex 5 with
With the PtN2 mean plane.
the hydrogen atoms removed for clarity.
Fig. 6 Perspective drawing (30% thermal ellipsoids) of the cation in
complex 6 with the hydrogen atoms removed for clarity.
Fig. 4 Perspective drawing (30% thermal ellipsoids) of the complex 4 with
the hydrogen atoms removed for clarity.
Absorption and emission spectra
Compared to complexes 4 and 5, in 6 the four-coordinated
platinum(II) is bonded to an adjacent ortho-carbon atom, the
nitrogen atom of the CNC ligand and P,N atoms of L (Fig. 6).
The least-squares plane through the atoms Pt(1), P(1), N(1), N(2)
The spectroscopic and photophysical data of 1–6 are summarized
in Table 2. Their UV-vis absorption spectra are characterized
by an absorption band at 350–356 nm with tails extending
to ca. 450 nm, which is assigned to a metal-to-ligand charge
transfer (MLCT): d(Cu)→p*(naphthyridine/CNN) for 1–3 and
d(Pt)→p*(naphthyridine) for 4–6.15,27–29 In comparison, the ab-
sorption at <350 nm is attributed to originate from the intraligand
(IL) p→p* transition.4
˚
and C(1) shows a mean deviation of 0.24 A. The plane defined
by Pt(1)–P(1)–N(1) atoms has a dihedral angle of 24.7◦ with the
Pt(1)–N(2)–C(1) mean plane. The Pt–P, Pt–C and average Pt–N
˚
bond lengths are 2.1878(9), 1.991(3) and 2.150(8) A, respectively.
The bite angles C(1)–Pt(1)–N(1) and N(3)–Pt(1)–P(1) are 80.0(1)
Upon excitation at 350–360 nm, complexes 1–6 exhibit a
photoluminescence with kmax at 390–425 nm in dichloromethane
and 83.27(8)◦, respectively.
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Table 2 Photophysical spectra data for complexes 1–6
Complex
Medium
CH2Cl2
Solid
kabs /nm (e/dm3 mol−1 cm−1
)
kem/nm (kex/nm)
423(350)
s/ns
φem
1
273 (26 650), 355 (18 550)
375 (13 700)
5.1
1341
0.077
525(350)
2
3
CH2Cl2
Solid
270 (41 650), 350 (13 450)
425(350)
540(350)
4.9
609
0.217
0.014
CH2Cl2
Solid
270 (34 534), 308 (26 657)
355 (13 157)
390(350)
450(350)
420(370)
490(370)
420(360)
480(370)
2.9
4
5
6
CH2Cl2
Solid
275 (21 190), 335 (22 488)
350 (24 833), 370 (20 143)
1.3
0.307
0.114
0.024
29500
5.1
2160
1.5
CH2Cl2
Solid
270 (20.260), 328 (18 490)
342 (21557), 357 (21 773)
CH2Cl2
Solid
270 (37 856), 350 (19 695)
395(360)
530/370
solution (2.0 × 10−5 M) at room temperature, with measured
emission quantum yields of 0.077, 0.217, 0.014, 0.307, 0.114
and 0.024, respectively. The short excited-state lifetimes (<10 ns)
and small Stokes shifts of these complexes indicate that the
emissions are the intraligand fluorescence. However, complexes
2 and 4 display intense solid-state emissions at 540 and 490 nm,
respectively. The emissions have relatively long lifetimes of 0.6
and 29.5 ls implying that these emissions originate from a triplet
excited state. In addition, time-resolved emission measurements
of solid samples of 2 and 4 revealed that the emissions follow
a single-exponential decay with microsecond lifetime magnitudes
(Fig. 7 and 8).
Fig. 8 Time-resolved emission spectra of 4 with excitation at 355 nm in
the solid state at room temperature.
photoluminescent mono- or binuclear Cu(I) and Pt(II) complexes
were prepared. X-Ray crystal analysis showed that complex
[(L)2Cu2](BF4)2 exhibits both P,N-chelating and –bridging
coordination modes, and has crystallographic C2 symmetry.
But when one coordinating point is occupied, ligand L bridges
two Cu(I) centers to form the binuclear complex 2. However,
one bidentate 6-phenyl-2,2ꢀ-bipyridine ligand was chelated to a
copper(I), resulting in a P,N-chelating mononuclear complex.
In comparison with the structures of copper(I) the ligand L
in the reported platinum(II) complexes having a square-planar
array adopts only a chelating mode to coordinate to metal
in a cis configuration, and the bonding mode is unaffected in
the presence of ancillary ligand. Spectroscopic investigations
suggest that solution emissions of these compounds at room
temperature are derived from an intraligand singlet excited state,
whereas relatively solid-state low-energy emissions are assigned to
3MLCT transition. This study provides novel information for the
Fig. 7 Time-resolved emission spectra of 2 with excitation at 355 nm in
the solid state at room temperature.
Conclusions
A new flexible N,P ligand 2-[N-(diphenylphosphino)methyl]-
amino-7-methyl-1,8-naphthyridine and its six types of
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development of flexible 1,8-naphthyridine-phosphine derivatives
with promising applications.
the mixture was evaporated until dry in vacuo, leaving a yellow
solid. Light yellow crystals suitable for X-ray diffraction were
obtained by diffusion of diethyl ether into a dichloromethane
solution. Yield: 88 mg (62%). 1H NMR (400 MHz, DMSO-d6): d
2.50 (s, 6H, CH3), 3.33 (s, 4H, CH2), 4.74 (broad, 2H, NH), 6.98
(d, J = 8.0 Hz, 2H), 7.00 (d, J = 8.9 Hz, 2H), 7.36 (t, J = 7.2 Hz,
8H), 7.45 (t, J = 7.2 Hz, 4H), 7.67 (broad, 8H), 7.89 (d, J = 8.9 Hz,
2H), 7.96 (d, J = 8.0 Hz, 2H). Anal. Calc. for C44H40B2Cu2F8N6P2:
C, 52.04; H, 3.97; N, 8.28. Found: C, 51.92; H, 3.93; N, 8.24%.
Experimental
Materials
All reactions were performed under
a nitrogen atmo-
sphere using standard Schlenk techniques unless otherwise
stated. The compounds [Cu(CH3CN)4]BF4, Pt(SMe2)2Cl2,30
(CNC)Pt(DMSO)Cl31 and 6-phenyl-2,2ꢀ-bipyridine32 as well as
starting material 2-methyl-7-amino-1,8-naphthyridine33 were pre-
pared according to previously published methods. Reagent grade
solvents were dried by standard procedures, and freshly distilled
prior to use. Solvents used in spectroscopic measurements were
HPLC grade, and solutions were degassed by employing at
least four freeze–pump–thaw cycles. All other chemicals were
obtained from commercial sources and used directly without
further purification.
Synthesis of complex (l-L)2Cu2(PPh3)2(BF4)2, 2
L, 100 mg (0.28 mmol), was added to an overnight stirred
solution of PPh3, 73 mg (0.28 mmol), and [Cu(CH3CN)4]BF4,
88.5 mg (0.28 mmol), in dichloromethane (30 ml), under a nitrogen
atmosphere at ambient temperature. After stirring the solution
for 4 h, the solvent was removed. Yield: 116 mg (54%). Yellow
single crystals were obtained by diffusion of diethyl ether into a
dichloromethane solution. 1H NMR (400 MHz, CDCl3): d 2.15 (s,
6H, CH3), 3.48 (s, 4H, CH2), 4.34 (broad, 2H, NH), 7.03 (broad,
20H), 7.17 (m, 20H), 7.33 (m, 10H), 7.48 (m, 2H), 7.53 (m, 4H),
7.64–7.73 (m, 2H). Anal. Calc. for C80H70B2Cu2F8N6P4: C, 62.39;
H, 4.58; N, 5.46. Found: C, 62.28; H, 4.54; N, 5.37%.
Instrumentation
1H, 13C and 31P NMR spectra were recorded on a DPX-400 Bruker
spectrometer and chemical shifts (d, ppm) were obtained relative
to tetramethylsilane (Me4Si) for 1H. Elemental analyses were
performed with a Carlo Erba 1106 element analysis instrument.
The UV-vis spectra were taken on a HITACHI U-3010 spec-
trophotometer, and the corrected emission spectra of solutions
and solids were obtained on a HITACHI F-4500 fluorescence
spectrophotometer adapted to a right-angle configuration at
room temperature. Time-resolved emission spectra and emission
lifetimes of the samples were performed with Single Photon Count
Technology on a FL920 Spectrometer (Edinburgh). Time-resolved
spectra were developed by measurement of the decays at individual
wavelengths.
Synthesis of complex [(L)Cu(CNN)]BF4, 3
6-phenyl-2,2ꢀ-bipyridine,
40
mg
(0.17
mmol),
and
[Cu(CH3CN)4]BF4, 56 mg (0.17 mmol), were mixed with
stirring in dichloromethane (30 ml) under a nitrogen atmosphere.
After 30 min, L, 62 mg (0.17 mmol), was added. The resulting
mixture was stirred overnight and concentrated to ∼2 ml.
Subsequent diethyl ether diffusion into the solution afforded
1
orange crystals in a 75% yield. H NMR (400 MHz, CDCl3): d
1.66 (s, 3H, CH3), 4.23 (s, 2H, CH2), 6.65 (d, J = 7.2 Hz, 1H),
6.99–7.10 (m, 5H), 7.20 (t, J = 7.2 Hz, 4H), 7.26–7.32 (m, 7H),
7.45–7.57 (m, 3H), 7.77 (s, 1H), 7.87 (d, J = 6.8 Hz, 1H), 8.08 (s,
1H), 8.15 (s, 1H), 8.22 (d, J = 6.5 Hz, 1H), 8.54 (s, 1H). Anal.
Calc. for C38H32BCuF4N5P: C, 61.68; H, 4.36; N, 9.46. Found: C,
61.53; H, 4.32; N, 9.57%.
Synthesis of 2-[N-(diphenylphosphino)methyl]amino-7-methyl-1,8-
naphthyridine, L
Diphenylphosphine, 4.65 g (0.025 mol), and paraformaldehyde,
0.75 g (0.025 mol), were added to a suspension of 3.98 g (0.025 mol)
2-methyl-7-amino-1,8-naphthyridine in toluene (100 ml). The
mixture was refluxed with stirring for 12 h under a nitrogen
atmosphere. The resulting solution was then cooled slowly to
−20 ◦C. A pale yellow crystalline solid was isolated by suction
filtration, and then washed with small portions of diethyl ether
and dried in vacuo. Yield: 5.47 g (61%). The crystalline solid was
characterized by H, 13C and 31P NMR. H NMR (400 MHz,
CDCl3): d 2.70 (s, 3H, CH3), 4.42 (t, J = 4.8 Hz, 2H, CH2), 4.82
(broad, 1H, NH), 6.52 (d, J = 8.7 Hz, 1H), 7.04 (d, J = 8.0 Hz,
1H), 7.34–7.39 (m, 6H), 7.47–7.52 (m, 4H), 7.69 (d, J = 8.7 Hz,
1H), 7.78 (d, J = 8.0 Hz, 1H). 13C NMR (CDCl3): d 25.0 (CH3),
39.8 (d, CH2), 111.7, 115.0, 118.1, 128.2, 128.3, 128.7, 132.4, 132.6,
135.8, 136.7, 158.5, 161.4. 31P NMR (CDCl3): d −17.21.
Synthesis of complex [(L)2Pt]Cl2, 4
A mixture of L, 92 mg (0.26 mmol), and Pt(SMe2)2Cl2, 50 mg
(0.13 mmol), in dichloromethane (30 ml) was stirred under a
nitrogen atmosphere at room temperature for 2 h. The mixture
gradually turned from yellow to clear colorless. The solvent was
removed in vacuo. The pale yellow crystals in 70% yield were
obtained by diffusion of diethyl ether into a dichloromethane
1
1
1
solution. H NMR (400 MHz, DMSO-d6): d 2.77 (s, 6H, CH3),
3.33 (s, 4H, CH2), 4.75 (broad, 2H, NH) 6.78 (d, J = 8.8 Hz, 2H)
7.04–7.08 (m, 10H), 7.29 (t, J = 8.0 Hz, 2H), 7.45 (t, J = 7.2 Hz,
4H), 7.57 (t, J = 7.2 Hz, 2H), 7.62 (d, J = 8.9 Hz, 2H), 7.73 (d,
J = 7.9 Hz, 2H), 8.13 (d, J = 8.0 Hz, 2H), 8.16 (d, J = 7.9 Hz,
2H). Anal. Calc. for C44H40Cl2N6P2Pt: C, 53.88; H, 4.11; N, 8.57.
Found: C, 53.85; H, 4.16; N, 8.59%.
Synthesis of complex (L)2Cu2(BF4)2, 1
Synthesis of complex [(L)2Pt](ClO4)2, 5
L, 100 mg (0.28 mmol), and [Cu(CH3CN)4]BF4, 88.5 mg
(0.28 mmol), were mixed in dichloromethane (30 ml) under a
nitrogen atmosphere. After stirring for 15 h at room temperature,
A mixture of 4, 100 mg (0.10 mmol), and excess LiClO4·3H2O,
160 mg (1.00 mmol), in acetonitrile (30 ml) was stirred under a
3098 | Dalton Trans., 2008, 3093–3100
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Table 3 Summary of X-ray crystallographic data for complexes 1–6
1
2
3
4·2CH2Cl2
5·CH2Cl2
6
Formula
C44H40B2Cu2F8N6P2 C80H70B2Cu2F8N6P4 C38H32BCuF4N5P
C46H44Cl6N6P2Pt
1150.60
Monoclinic
C45H42Cl4N6O8P2Pt C39H32N4PClPt
Formula weight
Crystal system
Space group
1015.46
Monoclinic
C2/c
1540.00
Triclinic
P1
740.01
Monoclinic
C2/c
1193.68
Monoclinic
P21/c
818.23
Monoclinic
C2/c
¯
P21/n
Crystal size/mm
0.21 × 0.14 × 0.12 0.22 × 0.18 × 0.14 0.66 × 0.20 × 0.18 0.40 × 0.380.35
0.32 × 0.18 × 0.16 0.24 × 0.20 × 0.18
˚
a/A
17.790(2)
16.382(2)
15.468(3)
90
97.821(3)
90
13.046(2)
13.073(2)
22.398(4)
88.669(3)
88.968(4)
74.638(3)
3682.3(11)
2
49.300(11)
12.055(3)
25.150(5)
90
109.728(5)
90
16.299(13)
16.892(14)
19.458(16)
90
113.498(9)
90
4913(7)
4
1.556
2288
3.286
1.39–28.80
30802
14.624(11)
17.326(12)
20.341(15)
90
110.453(7)
90
37.565(8)
10.6978(19)
22.217(5)
90
132.471(2)
90
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
3
˚
V/A
4466.0(11)
4
14069(5)
16
4829(6)
4
1.642
6586(2)
8
1.650
Z
Dc/g cm−3
F(000)
1.510
2064
1.389
1584
1.397
6080
2376
3.251
3232
4.426
l/mm−1
1.098
1.70–25.01
0.734
0.91–25.02
18971
0.723
1.65–25.01
36058
h range/◦
1.49–25.01
23953
1.47–27.89
30213
Reflections collected 11353
Rint
0.1425
352
0.979
0.0737
0.1732
0. 69, −0.546
0.0507
921
1.028
0.0569
0.1226
957
1.006
0.0536
550
1.015
0.0424
0.0887
2.862, −1.476
0.0460
639
1.019
0.0321
0.0766
1.61, −0.693
0.0422
420
1.078
0.0288
0.0659
2.135, −1.120
Parameters
Goodness of fit
R1a
0.0618
0.1294
0.508, −0.394
wR2a
0.1026
−3
˚
Dq/e A
0.660, −0.460
ꢀ
ꢀ
ꢀ
ꢀ
a I > 2r(I), R1 = ꢁFo| − |Fcꢁ |Fo|; wR2 = { [w(Fo − Fc2)2]/ [w(Fo2)2]}
.
2
1/2
nitrogen atmosphere at room temperature for 1 h. Next, the solvent
was concentrated down to ∼2 ml, excess diethyl ether was added
and a pale yellow solid was obtained. Recrystallization of the
crude product from a dichloromethane and diethyl ether solution
afforded pale yellow single crystals of 5·CH2Cl2 in 80% yield. 1H
NMR (400 MHz, DMSO-d6): d 2.77 (s, 6H, CH3), 3.32 (s, 4H,
CH2), 4.80 (broad, 2H, NH), 6.72 (d, J = 8.9 Hz, 2H), 7.05–7.14
(m, 10H), 7.30 (t, J = 7.2 Hz, 2H), 7.43–7.51 (m, 4H), 7.56 (t, J =
7.2 Hz, 2H), 7.62 (d, J = 8.9 Hz, 2H), 7.73 (d, J = 8.0 Hz, 2H),
8.14 (dd, J = 7.7 Hz, 4H). Anal. Calc. for C44H40Cl2N6O8P2Pt: C,
47.66; H, 3.64; N, 7.58. Found: C, 47.58; H, 3.57; N, 7.66%.
IP X-ray diffractometer. The diffraction data were corrected
for absorption correction using the ABSCOR program. The
structures were determined by direct methods using the program
SHELXS 97 and refined by full-matrix least squares on F2 using
the SHELXL 97 program package.34 The non-hydrogen atoms
were refined anisotropically. All hydrogen atoms were generated
geometrically, assigned appropriate isotropic thermal parameters
and included in structure factor calculations.
CCDC reference numbers 666202–666207.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b717777a
Synthesis of complex [(L)Pt(CNC)]Cl, 6
Acknowledgements
A mixture of (CNC)Pt(DMSO)Cl, 108 mg (0.20 mmol), and L,
71 mg (0.20 mmol), in chloroform (30 ml) was stirred overnight
under a nitrogen atmosphere at room temperature. The solvent was
concentrated down to ∼2 ml in vacuo. Addition of diethyl ether
gave a yellow solid. Yellow crystals (65% yield) were obtained by
The work was supported by the National Basic Research Program
of China (973 program 2005CCA06800, 2007CB613304), the
National Natural Science Foundation of China (NSFC Grant
No. 20761006, 20671094, 90610034). We thank the foundation
(50418010) for NSFC/RGC Joint Research.
1
diffusion of diethyl ether into a chloroform solution. H NMR
(400 MHz, CDCl3): d 2.78 (s, 3H, CH3), 3.47 (s, 2H, CH2), 4.67
(broad, 1H, NH), 6.70 (d, J = 7.8 Hz, 1H), 6.81 (d, J = 7.8 Hz,
1H), 6.90–7.14 (m, 4H), 7.30 (m, 4H), 7.43–7.55 (m, 8H), 7.68 (m,
2H), 7.76–7.93 (m, 4H), 7.97 (d, J = 7.8 Hz, 1H), 8.12 (d, J =
7.8 Hz, 1H). Anal. Calc. for C39H32ClN4PPt: C, 57.25; H, 3.94; N,
6.85. Found: C, 57.38; H, 3.96; N, 6.77%.
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