Hydrogen bonding in pure deuterated ethanol at solid state

Although very familiar, ethanol has a complex phase diagram. Surprisingly, structural information is very scarce. For pure ethanol, only one structural determination at low temperature in 1976 exists so far in the literature. The monoclinic Pc unit cell contains two independent molecules, only H-connected via the enol functional group, but C-H bonds lengths are questionable, as expected from old X-ray data. Neutron data are mandatory to properly explore bonding mechanisms in ethanol, vital for construction of reliable simulations of molecular structures with alcohol groups. Proposal focuses on the precise structure determination of this stable monoclinic phase of perdeuterated ethanol. Due to the monoclinic symmetry, at least 6 orientations (8-10h each) are needed plus one day to prepare the sample in situ: we ask 4 days of beamtime on SXD.

尽管乙醇为人熟知，但其相图（phase diagram）却极为复杂。令人意外的是，相关结构信息却十分匮乏。就纯乙醇而言，截至目前，文献中仅记载了1976年开展的一次低温结构测定（structural determination）工作。该单斜Pc晶胞（monoclinic Pc unit cell）内包含两个独立分子，二者仅通过烯醇官能团（enol functional group）实现氢连接，但受限于早期X射线衍射数据的固有局限，其中C-H键长的测定结果存疑。若要准确解析乙醇中的成键机制（bonding mechanisms），必须借助中子数据（neutron data）——这对构建可靠的醇基（alcohol groups）分子结构模拟工作至关重要。本研究提案旨在精准测定全氘代乙醇（perdeuterated ethanol）的该稳定单斜晶相结构。鉴于单斜对称性（monoclinic symmetry）的要求，实验需至少完成6组取向（orientations）（每组耗时8至10小时），且需1天时间完成原位（in situ）样品制备，因此我们申请在SXD仪器上使用4天的束流时间（beamtime）。