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首页> 外文期刊>Crystal growth & design >Sterically hindered aromatic tethered carboxylic acids: What is the critical length of the tether for adoption of centrosymmetric dimer synthon?
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Sterically hindered aromatic tethered carboxylic acids: What is the critical length of the tether for adoption of centrosymmetric dimer synthon?

机译：立体位阻芳族束缚羧酸：采用中心对称二聚体合成子的束缚关键长度是多少？

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The synthesis and X-ray structural investigations of sterically hindered aromatic tethered carboxylic acids have been carried out to examine the extent to which the tether modifies the molecular structures and the occurrence of strong O-H center dot center dot carried out to examine the extent to which the tether modifies the molecular structures and the occurrence of strong O-H center dot center dot center dot O hydrogen bond-mediated synthons of the carboxyl groups. The diacids based on mesitylene- and isodurene carboxylic acids (MA2 and DA2) containing a C-2-tether were found to exhibit pseudopolymorphism/solvatomorphism. Whereas a C-3-tethered dimesitoic acid MA3 crystallized only in the presence of 2,4,6-collidine as a guest, the isodurene analogue DA3 resisted crystallization. The adoption of the centrosymmetric dimer motif was observed for the butylene-tethered dimesitoic acid MA4. The situation appears to be a little relaxed for unhindered diacids such that a C-3-tether is sufficient for adoption of the centrosymmetric dimer synthon in the crystal lattice, as revealed by the crystal structure of 1,3-bis(m-carboxyphenyl)propane, BA3. The topological changes, that is, skewed (for odd) and extended (for even), imparted by the tether appear to render the close packing with simultaneous exploitation of the strong O-H center dot center dot center dot O hydrogen bonds difficult even for diacids with a C2-tether. Thus, for short chain lengths, the tether typically behaves like a functional group, which perturbs the molecular association based on O-H center dot center dot center dot O hydrogen bonds of the otherwise strongly interacting carboxyl groups.
机译：进行了位阻芳香族链式羧酸的合成和X射线结构研究，以研究链式修饰分子结构的程度以及强OH中心点中心点的出现，以检查系链修饰了分子结构以及强的OH中心点中心点中心点O氢键介导的羧基合成子的出现。发现基于含有C-2-束链的均三甲苯-和异戊二烯羧酸的二元酸（MA2和DA2）表现出假多态性/溶剂同型性。仅在作为来宾的2,4,6-可力丁存在下，C-3-系链的二甲磺酸MA3才结晶，而异戊二烯类似物DA3则抵抗结晶。中心连接的二聚体基序的采用被观察到的丁烯系的二聚二羧酸MA4。对于未受阻的二酸，情况似乎有些放松，因此C-3-系链足以在晶格中采用中心对称的二聚体合成子，正如1,3-双（间-羧基苯基）的晶体结构所揭示的那样丙烷，BA3。系链赋予的拓扑变化（即偏斜（奇数）和扩展（偶数））似乎使得紧密堆积，同时利用强OH中心点中心点中心点O氢键也很难，即使对于二元酸C2系绳。因此，对于短链长度，系链的行为通常类似于官能团，该官能团扰乱了以其他方式强烈相互作用的羧基的O-H中心点中心点中心点O氢键为基础的分子缔合。

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