León Iker, Millán Judith, Cocinero Emilio J, Lesarri Alberto, Fernández José A
Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Bo Sarriena s/n, Leioa 48940, Spain.
Phys Chem Chem Phys. 2014 Nov 14;16(42):23301-7. doi: 10.1039/c4cp03101f.
Spectroscopic studies of molecular aggregates are a powerful tool to understand the weak interactions between molecules. Here, propofol2(H2O)6,7 clusters were formed in supersonic expansions and their electronic and infrared spectroscopy was explored using several mass-resolved laser-based spectroscopic techniques. Using REMPI, their S1 ← S0 electronic spectrum was obtained with vibrational resolution, while the UV/UV hole burning revealed the presence of a single isomer of propofol2(H2O)6 and of two isomers of propofol2(H2O)7. Employment of IR/UV double resonance yielded the IR spectrum in the OH stretch region. Comparison with the spectra predicted for the structures calculated at the M06-2X/6-31+G(d) level demonstrated that the two propofol molecules interact mainly through C-Hπ contacts between the lipophilic sides of the molecules, while the hydroxyl moieties are in close contact, forming a kind of "active centre" with which the water molecules interact, forming polyhedral structures.
分子聚集体的光谱研究是理解分子间弱相互作用的有力工具。在此，在超声速膨胀中形成了丙泊酚2(H2O)6,7团簇，并使用多种基于激光的质量分辨光谱技术对其电子光谱和红外光谱进行了研究。利用共振增强多光子电离（REMPI），以振动分辨率获得了它们的S1←S0电子光谱，而紫外/紫外空穴烧蚀揭示了丙泊酚2(H2O)6存在单一异构体以及丙泊酚2(H2O)7存在两种异构体。采用红外/紫外双共振得到了OH伸缩区域的红外光谱。与在M06 - 2X/6 - 31+G(d)水平计算的结构所预测的光谱进行比较表明，两个丙泊酚分子主要通过分子亲脂侧之间的C - Hπ接触相互作用，而羟基部分紧密接触，形成一种“活性中心”，水分子与之相互作用，形成多面体结构。
