Chemistry of High-Energy Content Reagents

高能试剂化学

• 批准号: 9320375
• 负责人: Philip Froelich
• 金额: $ 15.5万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1995-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9320375&HistoricalAwards=false
• 关键词: Chemistry; Energy; Content; Reagents

The photochemical, photophysical, and spectroscopic properties of ion pairs formed from cationic dyes and anionic borates will be studied. The first question to be considered will be whether or not the boranyl radicals formed by one electron oxidation of borates are bound species. This will be addressed by application of time-resolved spectroscopic methods on picosecond and femtosecond time-scales. Since the lifetime of boranyl radicals is too short to permit measurement of the oxidation potential by electrochemical means, a kinetic method based on the Rehm-Weller equation will be applied to estimate their potentials. A series of borates will be prepared to investigate the effect of steric crowding in the borate upon the oxidation potential. Penetrated ion pairs will be prepared that have different encounter distances, orientation, and free energy changes for photoinitiated electron transfer reactions. With these various penetrated ion pairs, factors that control forward and back electron transfer will be analyzed. This grant from the Organic Dynamics Program supports the continuing work of Professor Gary B. Schuster at the University of Illinois. Ion pairs will be formed from positively charged dyes and negatively charged borates. The borates contain a total of four other carbon containing groups ( alkyl or aryl groups) bonded to the boron atom. These ion pairs will be irradiated with light which is absorb by the dye. An electron will be transfer from the dye to the borate, which will in turn cause an alkyl group to dissociate from boron in the form of a free radical (a carbon species with one unpaired electron). The efficiency of this reaction, which depends in part on the back-transfer of an electron to give the starting ion pair, will be studied as a function of the structure of the ion pair. These ion pairs have practical importance, since they can initiate polymerization upon irradiation with visible and infrared light. The wide co mmercial application of polymers makes these ion pairs of commercial interest.

将研究由阳离子染料和阴离子硼酸盐形成的离子对的光化学、光物理和光谱性质。首先要考虑的问题是，硼酸盐单电子氧化形成的硼基自由基是否为束缚态。这将通过在皮秒和飞秒时间尺度上应用时间分辨光谱方法来解决。由于硼酰自由基的寿命太短，不能通过电化学手段测量氧化电位，因此将采用基于Rehm-Weller方程的动力学方法来估计其电位。制备了一系列硼酸盐，以研究硼酸盐中空间拥挤对氧化电位的影响。在光引发的电子转移反应中，将制备具有不同接触距离、取向和自由能变化的穿透离子对。利用这些不同的穿透离子对，我们将分析控制正向和反向电子转移的因素。这项来自有机动力学项目的拨款支持了伊利诺伊大学Gary B. Schuster教授的持续工作。带正电的染料和带负电的硼酸盐会形成离子对。硼酸盐总共含有四个与硼原子相连的其他含碳基团（烷基或芳基）。这些离子对将被染料吸收的光照射。一个电子将从染料转移到硼酸盐上，这将导致烷基以自由基的形式与硼分离（一种带有一个未配对电子的碳物质）。这一反应的效率部分取决于电子的反向转移以产生起始离子对，将作为离子对结构的函数来研究。这些离子对具有实际意义，因为它们可以在可见光和红外光照射下引发聚合。聚合物的广泛商业应用使这些离子对具有商业价值。