Transcript Systematic Synthesis, Isolation, and Photophysical Properties of

Systematic Synthesis, Isolation, and
Photophysical Properties
of Linear-Shaped Re(I) Oligomers and
Polymers with 2-20 Units
Youhei Yamamoto, Shuhei Sawa, Yusuke
Funada, Tatsuki Morimoto,
，
Magnus Falkenstro¨m, Hiroshi Miyasaka, Sayaka Shishido, Tomoji
Ozeki, Kazuhide Koike, and Osamu Ishitani*
J. Am. Chem. Soc. 2008, 130, 14659–14674
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Linear-Shaped Metal Oligomers
[Co5(5-tpda)4(NCS)2]
[Ni5(5-tpda)4CI2]
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Shie-Ming Peng .Angen. Chem. Inr. Ed. Engl. 1997, 36, 56
Motivation
• Excellent emitters
Room-temperature luminescence, long lifetime
High emission quantum yield
• Molecular-scale photonic wires
N CO CO
Re
CO
N X
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Photochemical Ligand Substitution Reaction
Ishitani, O, et. Al, J. Am. Chem. Soc. 2002, 124, 11448–11455.
Schoonover, J. R. et. al, Inorg. Chem. 2001, 40, 5056–5057.
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Synthesis of a linear-shaped rhenium(I)
diimine complexes
Ishitani, O, et. Al, Chem. Commun., 2001, 1514–1515
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Photophysical Properties of linear-shaped
rhenium(I) diimine complexes
Fig. 1 (b) emission spectra (350 nm excitation)
of 14+, 2b3+, 32+ and 5+ in acetonitrile.
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Ishitani, O, et. Al, Chem. Commun., 2001, 1514–1515
Synthetic Strategy
“Target molecules”
LL
x
“Complex as metal”
“Complex as ligand”
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Synthesis of Linear-Shaped Rhenium(I) Complexes
ac = -PPh2-CC-PPh2h (>330 nm)
excess ac
fac-Re(bpy)(CO)3(CF3SO3)
0.5 eq ac
(i) h (>330 nm) in CH2Cl2 for 30 min; (ii) excess ac in CH2Cl2 at room temperature for 1 day, then at 40
°C for 1 day; (iii) fac-Re(bpy)(CO)3(CF3SO3) in CH2Cl2 at room temperature for 1 day, then at 40 °C for 1 8
day; (iv) ac (0.5 equiv) in CH2Cl2 at room temperature for 1 day, then at 40 °C for 1 day.
Synthesis of Oligomers with 5 and 7 Re(I) Units
Yield = 32%
(i) h (>330 nm) in CH2Cl2 for 1 h;
(ii) [Re2ac(η1-ac)1]2+ in CH2Cl2 at room temperature for 1 day, then at 40 °C for 1 day.
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Synthesis [Re5ac]5+ in higher yield
Yield = 66%
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Synthesis of Linear-Shaped Re(I) Polymers
(i) h (>330 nm) in MeCN for 1 h; (ii) excess ac in acetone/THF (1:1) at room temperature for 1 day, then
at 40 °C for 1 day; (iii) in acetone/THF (1:1) at room temperature for 1 day, then at 40 °C for 2 days.
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Separation Using Size Exclusion Chromatography
Figure S3. Chromatograms of analytical SEC. Reaction mixture (a), with isolation of [Re5ac]5+,
[Re10ac]10+, [Re15ac]15+, and [Re20ac]20+. The eluent was a 1:1 (v/v) mixture of methanol and
acetonitrile containing 0.3 M CH3CO2NH4, and the flow rate was 5.0 ml min-1. The detection
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wavelength was 360 nm.
ESI FTMS spectrum of [Re8ac]8+(PF6-)8.
ESI FTMS = electrospray ionization Fourier transform mass spectrometry
Figure 1. ESI FTMS spectrum of [Re8ac]8+(PF6-)8. The
eluent was MeCN.
Figure 2. ESI FTMS spectrum of the scale-extended segment for the seven
charged [M + (PF6-)]7+ (a) and calculated isotope distribution patterns(b).
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Aromatic regions in 1H NMR spectra
H6
H5
H4
H3
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Aromatic regions in 1H NMR spectra
Hi6
Hi3 Hi
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A( H ii 5  H iii 5 )
 1  0.5 x
i
A( H 6 )
Hii5
Hii5+Hiii5
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Identify the Longest Isolated Polymer Made from
[Re5ac]5+ by 1H NMR
A( H ii 5  H iii 5 )
 1  0.5 x
i
A( H n )
the number of Re(I)
units is 20.42.0
Figure 4. Relationship between the number of Re(I) units in the oligomers and polymers and ratios of the
integrated areas of their 1H NMR signals,A(H5 i + H5ii)/A(H6iii) (n = 3, 4, 6), measured in acetone-d3 at
room temperature. See the structure as shown in Figure 3 for numbering of the protons. The red circle is
the longest isolated polymer made from [Re5ac] 5+.
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IR spectra
 (interior Re-CO)
[Re8ac]8+
[Re6ac]6+
 (edge Re-CO)
[Re4ac]4+
[Re2ac]2+
Figure 5. IR spectra of [Re2ac]2+ (dotted line), [Re4ac]4+ (blue line), [Re6ac]6+ (red
line), and [Re8ac]8+ (solid black line) measured in MeCN. They are standardized by
the absorbance at 2048 cm-1.
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Identify the Longest Isolated Polymer Made from
[Re5ac]5+ by Ratio of  (CO)
A( 1885cm  1 )
 0.7906  0.4201x

1
A( 2048cm )
the number of Re(I)
units is 20.10.4
Figure 6. Relationship between the ratios of the ν(CO) peak areas due to edge units (2048 cm-1) and
interior units (1885 cm-1) of [Re2ac]2+ to [Re16ac]16+ (black dots), and the number of Re(I) units. The
red circle is the polymer for the longest isolated polymer made from [Re5ac]5+.
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Identify the Longest Isolated Polymer Made from
[Re5ac]5+ by Size Exclusion Chromatography.
the number of Re(I)
units is 20.63.7
Figure 7. The logarithm of the molecular weight plotted against the distribution
coefficient (KSEC) of the Re(I) oligomers and polymers. The red circle shows the longest
isolated polymer made from [Re5ac]5+.
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ORTEP diagram of [Re2ac]2+(PF6-)2
“Trans” - type
Bond Lengths
Inversion center
Bond Angles
π-π interaction
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Packing diagram of [Re2ac]2+(PF6-)2
π-π interaction
Figure S4. Packing diagram of [Re2ac]2+(PF6-)2, PF6- and hydrogen atoms omitted for clarity.
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ORTEP diagram of [Re3ac]3+(PF6-)3
Mirror
U-shaped
plane
Bond Lengths
Bond Angles
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ORTEP diagram of [Re3et]3+(PF6-)3
U-shaped
et = -PPh2-(CH2)2-PPh2-
Bond Lengths
Bond Angles
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ORTEP diagram of [Re4et]4+(PF6-)4
Circle-like structure
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UV-vis absorption spectra
  
MLCT
Figure 9. UV-vis absorption spectra of MeCN solutions containing [Re2ac]2+ to [Re20ac]20+
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Subtracted spectra UV-vis absorption spectrum
Figure 9. Subtracted spectra UV-vis absorption
spectrum of [Re2ac]2+ from those of [Re3ac]3+ to
[Re20ac]20+, divided by the number of
biscarbonyl complex units .
Figure 10. Subtracted spectra UV-vis absorption
spectrum of [Re2et]2+ from those of [Re3et]3+ [Re7et]7+, divided by the number of the biscarbonyl
complex units; the red line is the UV-vis absorption
spectrum of fac-[Re(bpy)(CO)2(PPh2Pr)2]+ in MeCN.
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Emission spectra
Red shift
Figure 11. Emission spectra from degassed MeCN solutions containing [Re2ac]2+ to [Re20ac]20+
standardized by the absorbance at the excitation wavelength 350 nm.
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Emission decay curves of [Re8ac]8+
Emission decay curves obtained at excitation wavelength of 365 nm.
(a) Monitor : 500 nm
(b) Monitor  : 650 nm
Main: 10 ns
Minor: 100 ns, 734 ns
Main: 113 ns, 750 ns
Minor: 10 ns
Iem(t)= A1 et⁄τ1 + A2 et⁄τ2 +A3 et⁄τ3
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Time resolved emission spectra of [Re8ac]8+
Figure 13. Time resolved emission spectra of [Re8ac]8+. Black, red, and blue
lines are emission spectra with lifetime of 10, 100, and 750 ns,respectively.
 = 10 ns is emission from the 3MLCT excitedstate of the edge Re(I) units.
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Photophysical Properties
Ket  Kr
Table 3. Photophysical Properties of [Re2ac]2+ to [Re20ac]20+ in a Deoxygenated Acetonitrile Solution
at 25 °C, and Energy Transfer Rates from the Edge Unit to the Interior Unit in [Re3ac]3+ to
[Re20ac]20+
aAll
complexes were PF6- salts. The excitation wavelength was 350 nm. bEmission maximum. cQuantum yield of
emission. dLifetime. Numbers in parentheses are percentages of pre-exponential factors,
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MeCN/toluene mixed solution effect em
em  Kr
cis,trans-[Re(bpy)(CO)2(PPh3)2]+
Figure 14. Dependence of Φem on toluene content in an
MeCN/toluene mixed solution.
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Conclusions
• We applied photochemical ligand substitution reactions
of Re(I) diimine complexes with a phosphorus ligand, to
find systematic synthetic routes for linear-shaped
rhenium(I) oligomers and polymers bridged with
bidentate phosphorus ligands.
• For oligomers and polymers with 3 Re(I) units, energy
transfer from the edge unit to the interior unit occurs
with a rate constant of (0.9 × 108)-(2.5 × 108) s-1.
• Crystal structures were obtained of some trimers and a
tetramer, showing interligand π-π interaction between
the diimine ligand and the phenyl groups on the
phosphorus ligand.
• Both emission and analytical SEC data indicate that the
Re(I) polymers aggregate intramolecularly in an MeCN 32
solution.