Karle Isabella L, Huang Lulu, Venkateshwarlu Punna, Sarma A V S, Ranganathan Subramania
Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, D.C. 20375-5341.
Heterocycles. 2009 Apr 1;79(1):471-486. doi: 10.3987/COM-08-S(D)4.
The structural features of the title compound were determined or examined by three diverse procedures: single crystal X-ray diffraction analysis, solution spectroscopic procedures and Quantum mechanical theoretical calculations. The conformational asymmetry of the macrocycle provides the opportunity to form one strong NH···OC intermolecular hydrogen bond, as well as, a number of weak CH···OC bonds. The interior of the macrocycle has short approaches for NH(...)π and NH···S. The many weak hydrogen bonds cooperate to form a very hard, robust crystal. Crystal parameters: C(18)H(22)N(2)O(6)S(2), P2(1)2(1)2(1), a = 5.108(1) Å, b = 18.948(4) Å, c = 21.029(3) Å, α = β = γ = 90°. Quantum chemical calculations have provided a strong foundation for weak hydrogen bonds. Contrary to popular belief the present work has conclusively proved that the importance of weak hydrogen bonds are perhaps underestimated since calculations show that the energy of duplex are significantly lower then estimated from the identified hydrogen bonding.
单晶X射线衍射分析、溶液光谱法和量子力学理论计算。大环的构象不对称性提供了形成一个强NH···OC分子间氢键以及许多弱CH···OC键的机会。大环内部存在NH(...)π和NH···S的短程作用。许多弱氢键共同作用形成了一种非常坚硬、坚固的晶体。晶体参数：C(18)H(22)N(2)O(6)S(2)，P2(1)2(1)2(1)，a = 5.108(1) Å，b = 18.948(4) Å，c = 21.029(3) Å，α = β = γ = 90°。量子化学计算为弱氢键提供了坚实的基础。与普遍看法相反，目前的工作最终证明，弱氢键的重要性可能被低估了，因为计算表明双链体的能量明显低于根据已确定的氢键估计的能量。
