钴超分子络合物中的氢键相互作用—59Co核磁共振研究及分子模拟

摘要

钴超分子络合物[12]aneN4[Co(CN)6],[18]aneN6[Co(CN)6],[24]aneN8[Co(CN)6],[16]aneN4[Co(CN)6],[24]aneN6[Co(CN)6]以及[32]aneN8[Co(CN)6]中,氢键相互作用的程度与它们在水溶液中的构象密切相关,从而引起59Co的化学位移向高场移动,并且其四极矩耦合作用也随构象发生了变化.实验证明,络合物中的氢键越强,化学位移越向高场移动,四极矩耦合作用也越大.另一方面,尺寸大的超分子具有较长的分子转动相关时间,也导致59Co具有较短的纵向弛豫时间.简而言之,59Co核磁共振不仅在小分子甚至在超分子络合物中都可以用作理想的探针研究分子的次层或弱相互作用.%The hydrogen bonding interactions in a series of cobaltic supramolec-ular complexes [12]aneN4 [Co(CN)6], [18]aneN6[Co(CN)6], [24]aneN8[Co(CN)6],[16]aneN4[Co(CN)6],[24]aneN6[Co(CN)6] and[32]aneN8[Co(CN)6]were studies and found to be closely related to the molecular conforma-tions in the aqueous solution. Such interactions caused the 59Co chemical shiftsto move towards upfield, and the quadrupolar interaction to change as well. Itwas observed in this study that stronger hydrogen bonding resulted in largerupfield shift of the 59Co chemical shifts and higher quadrupolar interaction inthe cobaltic supramolecular complexes. On the other hand, larger supramolec-ular sizes resulted in longer molecular rotational correlation time τc and shorter59Co longitudinal relaxation time (T1). In summary, 59Co NMR proves to bean ideal probe to investigate the second sphere or weak interaction in the cobal-tic supramolecular complexes in addition to the small molecules.