查看完整版本: Carbon 60 'Buckminsterfullerene'碳60巴基球

nanoquebec 2006-12-16 08:39

Carbon 60 'Buckminsterfullerene'碳60巴基球

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s$M%w,E^n(u3n0w| The photograph shows a copy of the paper model of C60 made by R.W.Henson at AERE Harwell in 1970 "In Science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs."L*H-A&\e G1{Z
  Sir Francis Darwin. Carbon 60 or 'Buckminsterfullerene' is a closed structure composed of 60 carbon atoms arranged in the form of a hollow ball. Twenty carbon hexagons are linked and bent into the shape of a sphere by the inclusion of twelve equally-spaced pentagonal 'holes'. This is sometimes poetically called a 'Buckyball'.
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C-G2MGg8b1RnM The structure was 'discovered', or proved to exist, by Robert Curl and Richard Smalley of Rice University, together with Sir Harold Kroto of the University of Sussex. This was published in 'Nature' in November 1985 (Nature 318, 162-163 1985), and had a mixed reception.... both criticism and enthusiastic acceptance. Most physicists and chemists had not expected that carbon would be found in another form. During the next few years further evidence was obtained that proved the proposed structure was correct. For this work, Kroto, Curl and Smalley were jointly awarded the 1996 Nobel Prize for Chemistry.$A*~r/p0q
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This new form of carbon was named after Richard Buckminster Fuller who was a pioneer in the design of the Geodesic dome often used in large building structures. A prime example of this was the dome for the 1967 Montreal World Exhibition. Fuller patented the geodesic dome in 1954!*K%gd0yC

-so0e^,} However, the first dome with this structure was built at the Carl Zeiss optical works at Jena in Germany in 1922 byZ0@8i?7[!t/T
Dr. Walter Bauersfeld. The design of the dome was almost incidental to his even more remarkable technical achievement: the invention of the 'Planetarium Projector'.
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Jh lx {k/Q/a The history of this structure is long and varied, but one early and interesting study was by D'Arcy Wentworth Thompson. In his book 'On Growth and Form' (Cambridge University Press 1942) Thompson shows that a hexagonal grid, of any size, can be closed into a polyhedron by the inclusion of twelve pentagons in its network. It is interesting to note that C60 would be the smallest size of such a symmetric net. Thompson's interest was in the study of the skeletons of microscopic sea creatures.
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Of course, much of the mathematical background to this subject stems from Euler, and even Euclid. A very sound, and readable, discourse on the subject of Polyhedra may be found in 'Mathematical Recreations & Essays' by W. W. Rouse Ball (Macmillan & Co. 1939 11th edition).
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%z4X U2d W A3_6L[c The idea of a hollow carbon cage structure was first proposed by David E. H. Jones writing in the New Scientist under the name of 'Daedalus' (New Sci. 32, 245 1966). He suggested that it may be possible to create giant hollow molecules by distorting a plane hexagonal carbon net by the addition of impurity atoms. This, he claimed, could introduce curvature, and hence close the net into a spherical shell. He did not explain how this might be achieved. d/KV7yD/YFn |
In his book 'The Inventions of Daedalus' (Freeman 1982), Jones expands this idea, and even quotes from the work of Thompson. Anyone who has ever read 'Daedalus' will know that his 'inventions' lie somewhere in the hazy borderline between the feasable, and the fantastic, and as such are not to be taken too seriously. At least not until 1985!!t| O7D L SI/o

FC+V }5fEE Perhaps the first mention of the C60 molecule in the literature was in an article by E. Osawa (Kagaku 25, 854-863 1970). Osawa predicted that such a molecule would be stable, and expanded this in more detail in a book on aromatic molecules the following year (Z. Yoshida and E. Osawa 'Aromaticity' 1971). Both these articles are in Japanese.pXTV&w@*]

x.p y#KS;i/SP Also in 1970, R. W. Henson , with no prior knowledge of 'Daedalus', nor of Osawa's work, proposed the structure and made a model of Carbon 60. At the time he was a member of the Graphite and Carbon Studies group at AERE Harwell, studying radiation damage in the graphite moderator of nuclear reactors. The evidence for this new form of carbon was very weak and was not accepted, even by his colleagues! It was never published. A recent edition of the 'Carbon' journal contains a belated acknowledgement of Henson's work in an editorial by Dr.P.A.Thrower. Carbon Vol 37 No.11 1677-1678 (1999).
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!bbiU,s E1R b In 1992 the international journal 'Carbon' published a special issue on Fullerenes (Carbon Vol 30 No.8).1JL smq9q%}`d/f%H
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An interesting account of the events leading up to the discovery of Carbon 60 can be found in a book by Jim Baggott:
5Sk7w1}2Q#j*BB 'Perfect Symmetry - The Accidental Discovery of Buckminsterfullerene' (Oxford University Press 1994).P*Cc;HI)IK/Fz(B

ji3F#`$f u g Also of interest: 'The Most Beautiful Molecule: An Adventure in Chemistry' by Hugh Aldersley Williams (Aurum Press 1994).~X Un]!{K;[
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Both these books were reviewed in 'Carbon' Vol 33 No.7 Page 1007.

nano 2006-12-16 09:55

[table=501][tr][td=2,1][align=left][b][url=http://carbon.imr.ac.cn/c-knowledge.htm][font=楷体_GB2312][size=3][color=#666666]炭素知识介绍[/color][/size][/font][/url][/b][/align][/td][/tr][tr][td=2,1]　[/td][/tr][tr][td=1,2,47][align=center][font=宋体][size=2][/size][/font][font=楷体_GB2312][size=3][img=47,40]http://carbon.imr.ac.cn/images/C60-Ih.jpg[/img][/size][/font][/align][/td][td=1,1,444][align=center][font=楷体_GB2312][size=3][b]富勒烯的化学和物理[/b][/size][/font][/align][/td][/tr][tr][td][align=center][font=Times New Roman](CHEMISTRY AND PHYSICS OF FULLERENE)[/font][/align][/td][/tr][/table][font=宋体][color=#000000] [/color][/font][font=宋体][color=#000000]自从1985年发现C60至今的17年间，C60及其富勒烯家族(包括纳米碳管)一直是活跃在科学舞台上的一颗耀眼的明星。C60的独特结构赋予了它一些特殊的性质。如掺杂碱金属的C60具有超导性能；C60具有长的三重激发态寿命，成为研究激发态化学和物理特性的理想平台；C60能有效地把3O2转变成1O2，量子效率几乎达到100%，从而具有优异的抗癌灭菌能力；C60具有优良的光导电性能，在光电子器件领域具有潜在的应用价值；包裹金属的C60，M@C60具有与C60不同的物理性能，引起物理学家和材料学家的浓厚兴趣。包裹放射性元素的C60可以减小金属对生物体的毒副作用而引起药学家的关注。十几年来，从事富勒烯研究的科学家，做了大量的工作，取得了长足的进展。这些工作大体上可以概括为：(1)研究富勒烯的化学性质，开发新的化学反应，总结反应规律；(2)富勒烯的改性：把C60和C70作为平台，接上具有特殊功能的基团，以改进富勒烯的电学，光学和磁学性能；(3)增加C60和C70在水中的溶解度，以便利用C60和C70的抗癌，灭菌特性。[/color][/font]e mQDD rB
[font=宋体][size=2][b]富勒烯负离子化学[/b][/size][/font][font=宋体] [/font][color=#000000][font=宋体]自从发现M3C60具有超导性能后，C60和C70金属盐的合成成为十分活跃的研究领域，物理学家用气相沉积法把碱金属、碱土金属以一定的原子计量沉积到C60和C70的薄膜上，经退火处理制备C60和C70金属盐。化学家则通过溶液路线用化学和电化学方法来合成富勒烯金属盐，多种价态的C60n-(n=1-6)均已合成出来。南京大学配位化学国家重点实验室开发了一种新的十分简便的方法，选择性地合成C60n-和C70n-(n=1-3)。这个方法的特点是用普通的还原剂如Zn，Sn，Na2S2O3和Al-Ni合金等，不必控制还原剂的化学计量，只要改变溶剂的极性，在碱性条件下可以选择性地生成C60n-和C70n-(n=1,2,3)，选择性为100%。[/font][/color][table=517][tr][td=1,1,105][align=center][font=宋体]Reduced product[/font][/align][/td][td=1,1,53][align=center][font=宋体]C601-[/font][/align][/td][td=1,1,79][align=center][font=宋体]C602-[/font][/align][/td][td=1,1,79][align=center][font=宋体]C701-[/font][/align][/td][td=1,1,79][align=center][font=宋体]C702-[/font][/align][/td][td=1,1,82][align=center][font=宋体]C703-[/font][/align][/td][/tr][tr][td][align=center][font=宋体]Solvent[/font][/align][/td][td][align=center][font=宋体]THF[/font][/align][/td][td][align=center][font=宋体]DMSO[/font][/align][/td][td][align=center][font=宋体]THF[/font][/align][/td][td][align=center][font=宋体]THF/DMSO[/font][/align][/td][td][align=center][font=宋体]DMSO[/font][/align][/td][/tr][/table][font=宋体][color=#000000][/color][/font][font=宋体][color=#000000]这是因为在不同极性的溶剂中富勒烯的氧－还电位是不同的，即随着溶剂极性的增大，C60和C70的还原电位向正的方向移动，变得容易还原。同时发现C60n-和C70n-(n=1,2,3)对O2极端敏感，但对水却是惰性的。这是与以前文献上报道的结果不同的地方。用这个方法制备了一系列碱金属和碱土金属的富勒烯盐。由于大部分无机盐溶于水而不溶于有机溶剂。因此，制备富勒烯负离子水溶液的方法为合成其它金属富勒烯盐创造了条件。 [/color][/font][color=#000000][/color]
9}:TPWt-nV;cy2i [font=宋体][size=2][b]富勒烯水溶胶[/b][/size][/font][font=宋体][color=#000000]已发现C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]和C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]的苯溶液具有把3O2转变成1O2的优异特性，量子产率接近100%。因此，可以用来杀死癌细胞，病毒和细菌。但是，有机溶液不能用于生物体系，而C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]和C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]几乎不溶于水，因此，寻找制备富勒烯水溶液的方法是一个富有挑战性的课题。文献已报道的方法有：(1)合成具有亲水基团的C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]和C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]衍生物，以增加它们在水中的溶解度。(2)利用水溶性的聚合物和大环化合物，如环糊精，环芳烃等将C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]和C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]包裹起来形成亲水的表面而溶于水。但这两种方法都有一些不利因素，即富勒烯衍生物中的加合基团破坏了富勒烯的对称性和电子结构，对1O2的量子产率产生不利的影响；包合物本身对生物效应会产生干扰，而影响实验结果。南京大学配位化学国家重点实验室开发了一种合成C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]和C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]水溶胶的方法，不需要加任何表面活性剂，水溶胶可以稳定半年以上。具体方法是把C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]-和C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]-溶液滴加到没有去气的蒸馏水中，就能得到不同浓度，不同胶粒大小的棕红色胶体溶液。实验表明这种胶体溶液具有优良的杀死癌细胞U937的能力。C[/color][/font][font=宋体][color=#000000]70[/color][/font][font=宋体][color=#000000]水溶胶的性能比C[/color][/font][font=宋体][color=#000000]60[/color][/font][font=宋体][color=#000000]水溶胶更好。[/color][/font]
8m,EE,Wsu6wYCi4M8JL [font=宋体][size=2][b]富勒烯的光物理性能[/b][/size][/font][font=宋体][color=#000000]C60具有较低的三重态能级，三重态的量子产率很高，加上三重态的吸收截面大于基态的吸收截面，因而具有优良的反饱和吸收性能，有可能在强光保护器中得到应用。从而引起了材料学家和物理学家的浓厚兴趣。实验结果表明富勒烯水溶胶也具有优良的反饱和吸收性能，由于水溶胶所含C60和C70的浓度比相应的有机溶液要高，反饱和吸收性能略好于富勒烯苯溶液。
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[/color][/font][font=宋体][color=#000000]为了改善富勒烯的光物理性能，各国学者合成了许多富勒烯衍生物。但效果并不理想。为了搞清其原因，笔者研究了C60(CN)2的光物理性质，用纳秒和皮秒脉冲宽度的激光器分别测定了三重态和单重态的光限性能，发现单重态的光限性能属于反饱和吸收机制而不是 双光子吸收效应。单重态的光限性能略优于C60，而三重态的光限性能与C60相似。瞬态吸收光谱表明C60(CN)2三重态的量子产率只有C60的1/6左右，但C60(CN)2三重态的吸收截面却比C60约大6倍。由于三重态的反饱和吸收性能取决于三重态的粒子数和吸收截面，两个相反的因素综合的结果导致C60(CN)2的三重态反饱和吸收性能与C60相似。由于三重态的粒子是从1S态的粒子经系际窜跃而来的。三重态量子产率的减小，表明由于CN基的加合，破坏了C60的对称性，减小了系际窜跃的速率。增加了1S态的粒子数，从而有利于荧光过程和单重态反饱和吸收性能的改善。这些结果表明C60衍生物不能改进其三重态的光限性能。[/color][/font]n'\ VAo
[font=宋体][size=2][b]富勒烯纳米粒子的组装[/b][/size][size=1](1) [/size][/font][font=宋体][color=#000000]二维组装。硅片经化学处理使其表面羟基化，再用偶联剂NH2(CH2)3Si(OCH3)3与羟基化的硅片作用，然后再与C60作用，得到组装在硅片上的C60纳米粒子单层膜。利用R-Si(OCH3)3作稀释剂，调节偶联剂和稀释剂的比例，可调节C60纳米粒子之间的距离，得到具有不同间距的超晶格。
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Az`9G#`$D;H7[ (2) 纳米线有序阵列。用Sol-gel法把C60和C70胶体粒子组装在阳极氧化铝膜的孔道内得到C60和C70单晶纳米线有序阵列。 j py,yh3@6rM

'e Gp0U q 富勒烯的化学和物理是一个内容十分丰富的新领域。富勒烯的三维空间结构和众多的双键为富勒烯化学的发展提供了广阔的空间。隐含了许多有待发现的新反应，它们的奇特特性也为材料科学，药物科学等的发展开辟了广阔的前景。[/color][/font] [font=宋体][color=#000000] w4Kt9`j7DL+L
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g,B ?]CVx7z ].D3G,` [[i] 本帖最后由 nano 于 2006-12-15 20:58 编辑 [/i]]
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查看完整版本: Carbon 60 'Buckminsterfullerene'碳60巴基球