Electron Delocalization in Saturated Molecules

饱和分子中的电子离域

• 批准号: 1566435
• 负责人: Josef Michl
• 金额: $ 53万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1566435&HistoricalAwards=false
• 关键词: Electron; Delocalization; Saturated; Molecules

The Chemical Structure, Dynamics, and Mechanism B Program of the NSF Chemistry Division supports the research of Professor Josef Michl in the Department of Chemistry and Biochemistry at the University of Colorado, Boulder. Professor Michl and his students are examining the nature of bonding in electronically excited states of chains of silicon atoms. These studies have practical implications for understanding fatigue in amorphous silicon solar cells exposed to ultraviolet radiation as well as understanding conductivity in materials comprised of silicon chains. The project is providing opportunities for the training of undergraduate and graduate students and postdoctoral researchers interested in lasers, in the interaction of light with matter, and in international science. Emphasis is being placed on attracting students to STEM fields, including those from groups that are presently underrepresented. The current understanding of electron delocalization in saturated molecules such as oligosilanes and polysilanes (silicon analogs of saturated hydrocarbons) lags far behind that in conjugated pi-electron systems. Geometrical distortions induced in peralkylated oligosilane chains by light absorption are particularly intriguing. Fluorescence reveals that they are negligible in long chains and very pronounced in chains containing fewer than about seven silicon atoms. Calculations suggest that the distortions can be described as a transformation of one or two of the silicon atoms from the normal tetrahedral to trigonal bipyramidal geometry, in which silicon used five "valence" orbitals instead of the usual four. Such expansion of the silicon valence shell would have fundamental importance for bonding theory. Professor Michl's group is attempting to verify the theoretical prediction experimentally, using vibrational spectroscopy of the short-lived excited species. The same methods of transient vibrational spectroscopy are useful for other photophysical problems, in particular in the investigation of materials known to undergo efficient singlet fission, such as the higher polyacenes and derivatives of isobenzofuran. The work involves continuing international collaborations, providing undergraduate students a research experience, and giving classroom demonstrations to high school students.

美国国家科学基金会化学部的化学结构、动力学和机制B项目支持博尔德市科罗拉多大学化学和生物化学系Josef Michl教授的研究。 Michl教授和他的学生正在研究硅原子链电子激发态的键合性质。这些研究对于理解暴露于紫外线辐射的非晶硅太阳能电池的疲劳以及理解由硅链组成的材料的导电性具有实际意义。该项目为培训对激光、光与物质的相互作用和国际科学感兴趣的本科生、研究生和博士后研究人员提供了机会。重点是吸引学生进入STEM领域，包括那些目前代表性不足的群体。目前对饱和分子如低聚硅烷和聚硅烷（饱和烃的硅类似物）中电子离域的理解远远落后于共轭π电子系统。光吸收引起的全烷基化低聚硅烷链的几何畸变特别有趣。荧光显示，它们在长链中可以忽略不计，在含有少于约7个硅原子的链中非常明显。计算表明，这种扭曲可以被描述为一个或两个硅原子从正常的四面体到三角双锥几何结构的转变，其中硅使用五个“价”轨道而不是通常的四个。硅价层的这种膨胀对成键理论具有根本的重要性。Michl教授的团队正试图通过实验验证理论预测，使用短寿命激发物种的振动光谱。同样的瞬态振动光谱方法也适用于其他物理问题，特别是在研究已知会发生有效单线态裂变的材料，如高级多并苯和异苯并呋喃的衍生物。这项工作包括继续国际合作，为本科生提供研究经验，并为高中生提供课堂演示。

项目成果

Anodic Oxidation of 18 Halogenated and/or Methylated Derivatives of CB 11 H 12 –

CB 11 H 12 的 18 种卤化和/或甲基化衍生物的阳极氧化 –

• DOI: 10.1021/acs.inorgchem.6b02126
• 发表时间: 2017
• 期刊: Inorganic Chemistry
• 影响因子: 4.6
• 作者: Wahab, Abdul;Douvris, Christos;Klíma, Jiří;Šembera, Filip;Ugolotti, Juri;Kaleta, Jiří;Ludvík, Jiří;Michl, Josef
• 通讯作者: Michl, Josef

Electrochemical Oxidation of [1-X-12-I-CB 11 Me 10 – ] Anions: Formation of Borenium Ylides [12-Dehydro-1-X-CB 11 Me 10 ] and Iodonium Ylide Anions [{12-(1-X-CB 11 Me 10 – )} 2 I + ]

[1-X-12-I-CB 11 Me 10 – ]阴离子的电化学氧化：形成硼叶立德[12-DeHydrogen-1-X-CB 11 Me 10 ]和碘鎓叶立德阴离子[{12-(1

• DOI: 10.1021/acs.inorgchem.6b02128
• 发表时间: 2016
• 期刊: Inorganic Chemistry
• 影响因子: 4.6
• 作者: Wahab, Abdul;Kaleta, Jiří;Wen, Jin;Valášek, Michal;Polášek, Miroslav;Michl, Josef;Ludvík, Jiří
• 通讯作者: Ludvík, Jiří

Electronic Transitions in Conformationally Controlled Peralkylated Hexasilanes

构象控制的全烷基化六硅烷中的电子跃迁

• DOI: 10.1002/cphc.201600633
• 发表时间: 2016
• 期刊: ChemPhysChem
• 影响因子: 2.9
• 作者: Kanazawa, Yuki;Tsuji, Hayato;Ehara, Masahiro;Fukuda, Ryoichi;Casher, Deborah L.;Tamao, Kohei;Nakatsuji, Hiroshi;Michl, Josef
• 通讯作者: Michl, Josef