Understanding solution based syntheses of inorganic materials in ionic liquids: Peering into the reaction mechanism from birth to age

近年来，基于离子液体的各种结晶无机材料的合成已经发展起来，与传统的合成方法相比，具有更好的性能和方案，但传统的合成方法仍然缺乏机理上的了解。我们的目的是阐明不寻常的修饰的二氧化钛的合成，即青铜相(二氧化钛(B))和最近合成的六方氧氟氧钛，它们都是通过使用普通离子液体与水的混合物和TiCl4作为前驱体在令人惊讶的温和反应条件下获得的。我们以前的实验证明了含氟离子液体在阴离子和不同侧链长度的阳离子头部基团上的混合物中的重要性，本项目的主要任务是从力学上了解含IL前驱体溶液的分子结构与钛氟羟基络合物的生成之间的联系，进而在分子水平上形成团簇，以及它们转化为金属氧化物核并生长成纳米粒子。我们将通过改变实验参数，即离子液体中的成分(使用[F]-而不是[BF4]-)和使用其他钛前驱体如[NH4][TiF6]来实现这一任务。采用原位方法(拉曼、X射线衍射、小角散射)在分子和纳米尺度上对相关物种进行了探测。同时，这种出生和衰老过程将通过特殊技术进行计算，提供分子水平的洞察力，并确认或纠正来自实验的假设。为此目的，新的相互作用势也将被参数化，紧随其后的是在飞行中评估电子结构的技术的应用，因此不需要先验的参数化。将建立额外的计算机实验，处理实验难以获得的关键数据，例如局域极性、特定相互作用和中间体络合物/簇合物的稳定性。

In recent years, a variety of ionic-liquid-based syntheses of crystalline inorganic materials has been developed, offering advantageous properties and protocols in comparison to conventional syntheses, which however still lack mechanistic understanding. We aim at elucidating the synthesis of unusual modifications of TiO2, namely the Bronze phase (TiO2(B)) and a recently synthesized hexagonal Ti oxyhydroxy fluoride, which are both obtained by surprisingly mild reaction conditions using mixtures of common ionic liquids with water, and TiCl4 as precursor. Our previous experiments proved the importance of ionic liquids containing fluorine in the anion and mixtures of different side-chain lengths attached to the cationic head groups.The main task of the project is to mechanistically understand the connections between the molecular structure of the IL-containing precursor solution and the generation of titanium fluoro hydroxo complexes and further the cluster formation on the molecular level, as well as their transformation into metal oxide nuclei and growth into nanoparticles. We will approach this task by variation of experimental parameters, i.e. the constituents in the ionic liquid (using [F]- instead of [BF4]-) and employing other Ti precursors such as [NH4][TiF6]. In-situ methods (Raman, X-ray diffraction, small-angle scattering) are applied to probe the relevant species on the molecular and nanometer scale. At the same time this birth as well as the aging process will be calculated by special techniques providing a molecular level insight and confirming or correcting assumptions from experiments. For this purpose also new interaction potentials will be parametrized next to the application of techniques which evaluate the electronic structure on the fly and thus work without a priori parametrization. Additional computer experiments will be set up addressing key data, which are hardly accessible to experiments, for instance local polarity, specific interactions, and stability of intermediate complexes/clusters.