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

近年来，已经开发了结晶无机材料的各种基于离子液体的合成，与常规合成相比提供了有利的性质和方案，然而常规合成仍然缺乏对机理的理解。我们的目的是阐明合成的不寻常的修改的二氧化钛，即青铜相（二氧化钛（B））和最近合成的六方钛羟基氟化物，这都是通过令人惊讶的温和的反应条件下使用常见的离子液体与水的混合物，和TiCl 4作为前体。我们前期的实验证明了阴离子中含氟离子液体和阳离子头基上连接的不同侧链长度的混合物的重要性，本项目的主要任务是从分子水平上理解含氟离子液体前体溶液的分子结构与钛氟羟基络合物生成之间的联系，并进一步理解簇合物的形成，以及它们转变成金属氧化物核和生长成纳米颗粒。我们将通过改变实验参数，即离子液体中的组分（使用[F]-代替[BF 4]-）和使用其他Ti前体如[NH 4][TiF 6]来完成这一任务。原位方法（拉曼，X射线衍射，小角散射）适用于探测分子和纳米尺度上的相关物种。与此同时，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，并确认或纠正实验中的假设。为此目的，新的相互作用势也将参数化的应用程序的技术，评估电子结构的飞行，因此没有先验参数化的工作。额外的计算机实验将设置解决关键数据，这是很难访问的实验，例如局部极性，特定的相互作用，和稳定性的中间复合物/集群。

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.