尿素类化合物在生命科学领域中有非常重要的作用,其独特的化学结构可与水等其他氢键给体材料形成氢键.氢键是生命分子体系中较常见和重要的分子间弱的相互作用,振动光谱方法为分子间氢键相互作用的研究提供有力的测量手段,其中拉曼光谱为研究水溶液中氢键形成和变化规律提供了可能.测得了1,3-二甲基脲(DMU)晶体的拉曼光谱,利用密度泛函理论(DFT)在B3LYP/6-311G**水平上对气态单体DMU进行结构的优化,并结合文献对拉曼光谱的谱线进行了归属认证.然后测得了1,3-DMU与水二元体系的拉曼光谱.相比与DMU晶体,当DMU分子溶于水后,水-DMU氢键相互作用将取代DMU-DMU分子间相互作用,导致氮原子杂化方式由sp2向sp3杂化转变.由此溶解过程中DMU分子的骨架从平面结构变成了非平面结构.

Urea family plays significant role in the bio-science area.Because of the unique frame,they can form Hydrogen bond with water as well as other substance.Hydrogen bonds are normal weak interactions in the system of bio-molecules.A Raman spectrum is the most powerful method to obscure the Hydrogen bond interaction between molecules.Initially,we measure the Raman spectra of DMU crystal,and then use density function theory with a B3LYP/6-311G** basis set to optimize the geometry structure and calculate the vibrational frequency of gas phase DMU,which assigns the Raman pecks.Then,measure the solvent.When dissolving DMU in water,the interaction between DMU-DMU will replaced by the interaction between water-DMU.The orbital hybridization of nitrogen atoms changes from the solid-state the sp2 orbital hybridization to sp3.So,the frame of this molecule goes from in-planet to out of plant during this process.