González Sandra Rodríguez, Nieto-Ortega Belén, González Cano Rafael C, Lloveras Vega, Novoa Juan J, Mota Fernando, Vidal-Gancedo José, Rovira Concepció, Veciana Jaume, del Corro Elena, Taravillo Mercedes, Baonza Valentín G, López Navarrete Juan T, Casado Juan
Department of Physical Chemistry, University of Málaga, Campus de Teatinos s/n, Málaga 29071, Spain.
Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (CSIC), Campus Universitari de Bellaterra, E-08193 Cerdanyola, Barcelona, Spain.
J Chem Phys. 2014 Apr 28;140(16):164903. doi: 10.1063/1.4871895.
We present a complete Raman spectroscopic study in two structurally well-defined diradical species of different lengths incorporating oligo p-phenylene vinylene bridges between two polychlorinated triphenylmethyl radical units, a disposition that allows sizeable conjugation between the two radicals through and with the bridge. The spectroscopic data are interpreted and supported by quantum chemical calculations. We focus the attention on the Raman frequency changes, interpretable in terms of: (i) bridge length (conjugation length); (ii) bridge conformational structure; and (iii) electronic coupling between the terminal radical units with the bridge and through the bridge, which could delineate through-bond spin polarization, or spin delocalization. These items are addressed by using the "oligomer approach" in conjunction with pressure and temperature dependent Raman spectroscopic data. In summary, we have attempted to translate the well-known strategy to study the electron (charge) structure of π-conjugated molecules by Raman spectroscopy to the case of electron (spin) interactions via the spin delocalization mechanism.
我们展示了一项完整的拉曼光谱研究，该研究针对两种结构明确、长度不同的双自由基物种，它们在两个多氯代三苯甲基自由基单元之间引入了对亚苯基乙烯撑桥，这种布局使得两个自由基之间能够通过桥并与桥进行可观的共轭。光谱数据通过量子化学计算进行解释和支持。我们将注意力集中在拉曼频率变化上，这些变化可以从以下几个方面进行解释：（i）桥的长度（共轭长度）；（ii）桥的构象结构；（iii）末端自由基单元与桥以及通过桥的电子耦合，这可以描绘出通过键的自旋极化或自旋离域。通过使用“低聚物方法”并结合压力和温度依赖的拉曼光谱数据来解决这些问题。总之，我们试图将通过拉曼光谱研究π共轭分子电子（电荷）结构的著名策略应用于通过自旋离域机制研究电子（自旋）相互作用的情况。
