Odd-Even Effects: Diamondoid and Quartz Networks by Bis(pyridylcarboxamido)alkanes Containing Alkyl Chains with an Odd Number of -(CH2)- Groups as Spacers
Odd-Even Effects: Diamondoid and Quartz Networks by Bis(pyridylcarboxamido)alkanes Containing Alkyl Chains with an Odd Number of -(CH2)- Groups as Spacers
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DOI：
10.1021/cg101493k
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发表时间：
2011-04-01
影响因子：
3.8
通讯作者：
Biradha, Kumar
中科院分区：
文献类型：
--
作者：
Mukherjee, Gargi;Biradha, Kumar
分析了具有奇数个碳原子的双（吡啶基羧胺）烷烃衍生物的晶体结构，发现其结构和物理性质与偶数类似物有很大的不同。该系列的偶分子表现出通过N- h中心点中心点中心点N或N- h中心点中心点中心点O氢键形成一维或二维结构的显著倾向，而奇数分子则表现出通过N- h中心点中心点中心点N氢键形成金刚石或石英等4倍互穿的三维网络。与偶数的线性构象相比，该系列的奇数成员已被发现采用扭曲构象。奇数类似物的熔点比对应的偶基团(R)为苯基时的熔点低。然而，当R基团是4-吡啶基或3-吡啶基时，MP值没有观察到这种趋势。这些材料的密度随着链长的增加而系统地降低，并且不依赖于间隔剂中- ch2 -基团的奇数和偶数。
Crystal structures of the homologous series of bis(pyridylcarboxamido)alkane derivatives having an odd number of carbon atoms in the alkyl spacer were analyzed and found to exhibit interesting structural and physical properties which differ significantly from those of their even analogues. The even members of this series have shown a remarkable preference to form one- or two-dimensional structures via N-H center dot center dot center dot N or N-H center dot center dot center dot O hydrogen bonds, while the odd ones have preferably exhibited 4-fold interpenetrated 3D networks such as diamondoid or quartz topologies via N-H center dot center dot center dot N hydrogen bonds. The odd members of the series have been found to adopt twisted conformations, in contrast to the linear conformation of the even ones. The melting points of the odd analogues are found to be lower than those of corresponding even members when the attached group (R) is a phenyl. However, such a trend in MP values has not been observed when the R group is a 4-pyridyl or 3-pyridyl group. The densities of these materials are found to decrease systematically with an increase in chain length and did not exhibit any dependence on the odd and even number of the -CH2- groups in the spacers.