The crystal structure of the homodimer formed by the tritolylurea 3a proves the existence of a belt of six bifurcated hydrogen bonds between both NH and the OC groups of the adjacent urea residues. For the tritosylurea 3b, four additional three-center hydrogen bonds, also involving the SO2 oxygen, are found in the crystalline state. Molecular dynamics simulations in a chloroform box confirm these patterns of the hydrogen bonds and the resulting elongation of the dimer 3b·3b in comparison to 3a·3a. The calculated complexation energies for the three dimeric combinations are nearly identical in agreement with the simultaneous formation of heterodimer 3a·3b in a mixture of 3a and 3b.
由三苯甲酰
脲3a形成的同二聚体的晶体结构证明,在相邻
脲残基的NH和OC基团之间存在一条由六个分叉氢键组成的带状结构。对于三苯甲酰
脲3b,在晶体状态下发现了另外四个三中心氢键,其中也涉及SO2氧。在
氯仿盒中进行分子动力学模拟,证实了这些氢键模式以及与3a·3a相比,3b·3b二聚体产生的伸长。计算出的三种二聚体组合的络合能量几乎相同,这与在3a和3b的混合物中同时形成异二聚体3a·3b相一致。