Order and Conformation of Biphenyl in Cyanobiphenyl Liquid Crystals: A Combined Atomistic Molecular Dynamics and 1H NMR Study
Order and Conformation of Biphenyl in Cyanobiphenyl Liquid Crystals: A Combined Atomistic Molecular Dynamics and 1H NMR Study
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DOI：
10.1002/cphc.201400082
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发表时间：
2014-05-19
期刊：
影响因子：
2.9
通讯作者：
Zannoni, Claudio
中科院分区：
文献类型：
--
作者：
Pizzirusso, Antonio;Di Pietro, Maria Enrica;Zannoni, Claudio
采用预测原子分子动力学（MD）模拟和H-1液晶核磁共振（LXNMR）残余偶极耦合测量相结合的方法研究了联苯（2P）在4-n-戊基-4-氰基苯（5CB）和4-n-辛基-4-氰基苯（8CB）液晶相中的排列。并与LXNMR进行了详细的比较和验证，结果表明，在相同还原温度下，模拟偶极耦合与实验偶极耦合具有良好的一致性。然后用MD检查近晶相中2P的位置，这是LXNMR无法获得的，发现2P分布相当均匀。MD和NMR的结合提供了详细的信息，关于顺序，取向和构象之间的相互作用，局部位置顺序，以及与液晶溶剂的相互作用。
The alignment of biphenyl (2P) in the liquid-crystal phases of 4-n-pentyl-4-cyanobiphenyl (5CB) and 4-n-octyl-4-cyanobiphenyl (8CB) is investigated by using a combination of predictive atomistic molecular dynamics (MD) simulations and H-1 liquid-crystal nuclear magnetic resonance (LXNMR) residual dipolar coupling measurements. A detailed comparison and validation of the MD results with LXNMR is provided, showing a good agreement between the simulated and experimental dipolar couplings at the same reduced temperature. MD is then used to examine the location of 2P in the smectic phase, which is unavailable to LXNMR, and 2P is found to be rather uniformly distributed. The combination of MD and NMR spectroscopy provides detailed information about the order, interconnection between orientation and conformation, local positional order, and interactions with the liquid-crystalline solvent.