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Dark-Field Oxidative Addition-Based Chemosensing: New Bis-cyclometalated Pt(II) Complexes and Ph

osphorescent Detection of Cyanogen Halides

Samuel W. Thomas III, Koushik Venkatesan, Peter Muller, and Timothy M. Swager

J. Am. Chem. Soc. 2006, 128, 16641 -16648

演講者：李光凡

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Blue-Shifting Transduction Event

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Phosphorescence

ATKINS’ Physical Chemistry 8th EDITION p 494

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Ir(ppy)3 Ir(thpy)3Pt(ppy) Pt(o,p-tpy)

Thompson, M. E. Inorg. Chem. 2002, 41, 3055-3066

Ueno, K. J. Am. Chem. Soc. 2003, 125, 12971-12979

Highly Phosphorescent Bis-Cyclometalated Complexes

Metal ： Pt & Ir

Ligand ： bidentate ligand. ex : 2 - phenylpyridine

5von Zelewsky, A. Inorg. Chem. 1987, 26, 2814-2818Stoeckli-Evans, H. Inorg. Chem. 1996, 35, 4883-4888

Homoleptic Complexes and Heteroleptic Complexes

Homoleptic Complexes

Heteroleptic Complexes

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Oxidative Addition Reactions

von Zelewsky, A. Inorg. Chem. 1987, 26, 2814-2818

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Some Phosphorescent Complexes Designed for The Sensing of other Vapors

Pilato, R. S. J. Am. Chem. Soc. 1998, 120, 12359-12360Swager, T. M. J. Am. Chem. Soc. 2003, 125, 3420-3421

Past ： Now ： Cyanogen halides

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1b ： R=CH3 – 97%

1c ： R=OCH3 – 93%

2a ： R=H – 62%

2b ： R=CH3 – 51%

Synthesis of thpy Ligands

1d ： 4-methyl – 68%

1e ： 5-methyl – 29%

1f ： 6-methyl – 96%

Stille coupling

Suzuki coupling

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Synthesis of Bis-Cyclometalated Pt(II) Complexes 3

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Synthesis of Bis-Cyclometalated Pt(II) Complexes 4

Steric congestion

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Synthesis of Bis-Cyclometalated Pt(II) Complexes 5

1a ： thienylpyridine

N

S

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Photophysical Parameters of Pt(II) Complexes 3-5

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Normalized UV/vis Spectra of Complexes 3a-d in THF

MLCT

Ligand-centered absorption

3a in THF ： 423 nm

3a in acetone ： 419 nm (blue-shift)

3a in toluene ： 430 nm (red-shift)

3b and 3c electron density↑ (red-shift)

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Normalized UV/vis Spectra of Complexes 3e, 3f, 4a, and 5 in THF

3f & 4a ： broadened MLCT absorbance band.

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Room-Temperature Emission Spectra of Phosphorescent Bis-Cyclometalated Pt(II) Complexes in THF

Quantum yields of emission between 0.05 and 0.30

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X-ray Crystal Structures of 3b (left) and 3f (right)

Pt1 – N1 = 2.169 Å

Pt1 – N2 = 2.165 Å

Pt1 – C7 = 1.985 Å

Pt1 – C17 = 1.982 Å

Pt1 – N1 = 2.139 Å

Pt1 – N2 = 2.179 Å

Pt1 – C3 = 1.98 Å

Pt1 – C13 = 1.974 Å

Slightly distort

16.4°

Severely distort

46.4°

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UV/vis Spectra of 3b During Its Reaction with 1.0 M MeI in Benzene

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Pseudo-First-Order Rate Plot for 3b in 1.0M MeI/Benzene

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UV/vis, for 3a, with Either MeI or BrCN (in Benzene)

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UV/vis Spectra of 3b React with 0.00013 M BrCN in Benzene

MLCT disappearance

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First-Order Kinetic Plot for The Reaction of 3b with BrCN

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Percentage Conversion of 3a In Either Toluene or Benzene

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Conversion Percentages of Several Pt(II) Complexes

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Bimolecular Rate Constants of Platinum Complexes with MeI in Benzene

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What Is PMMA?

1.聚甲基丙烯酸甲酯，又稱做壓克力或有機玻璃。

2.可見光： PMMA 是目前最優良的高分子透明材料，透光率達到 92 ％，比玻璃的透光度高。

3.紫外光：石英能完全透過紫外線，但價格高昂，普通玻璃只能透過 0.6 ％的紫外線，但 PMMA 卻能透過 73 ％。

http://zh.wikipedia.org/w/index.php?title=%E9%A6%96%E9%A1%B5&variant=zh-tw

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Normalized Emission Spectra of 3a In degassed THF Solution and Doped into PMMA Films

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PMMA/Pt(II) Spun-Cast Films of 4a (Top) and 3a (Bottom) under UV Light

+ BrCN

S

N

S

NPt

S

N

S

NPt

N

S

N

S

Pt

N

S

N

S

Pt + BrCN

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PMMA Film Emission Spectra of 3a (a) and 4a (b) before (Dotted) and after (Solid) Exposure to BrC

N Vapor for 15 s

S

N

S

NPtN

S

N

S

Pt

3a 4a

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Conclusions

• A new dark-field turn-on optical chemosensing scheme has been developed using bis-cyclometalated platinum complexes. A series of these complexes was synthesized, most of which have not been previously reported in the literature.

• Thin polymer films containing these complexes, which were phosphorescent at room temperature, also reacted with cyanogen halide vapors to give the blue-shifted Pt(IV) products.

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HOMEWORK1.BrCN接到此錯合物的構型是 cis或是 trans ?Ans: 由此文章中得知，當結構扭曲越嚴重時 BrCN 接上的速度越快，代表不可

能是 trans 的構型因此是屬於 cis 的結構，因此由構造可以再次證明 BrCN是屬於 SN2 的反應。且由本文中的圖 1 可推出構造可能是 cis 。

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HOMEWORK2.Homoleptic和 Heteroleptic有哪些不同之處 ?Ans: 由 table 1 知道 Homoleptic complex 3a 的量子產率比 Heteroleptic complex 5

的量子產率明顯高很多，代表 Homoleptic complex 的放光強度比 Heteroleptic complex 高出許多。而 Heteroleptic complex 5 和 BrCN 反應的速率比 Homoleptic complex 3a 和 BrCN 反應的速率快，作者在此篇文章說原因不明，個人猜測是因為 3a 上的 S 會拉電子導致 BrCN 接上的速度比較慢。