Engle Jeffrey M, Lakshminarayanan P S, Carroll Calden N, Zakharov Lev N, Haley Michael M, Johnson Darren W
Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1253 (USA).
Cryst Growth Des. 2011 Nov 2;11(11):5144-5152. doi: 10.1021/cg201074v.
The conformations of 2,6-bis(2-anilinoethynyl)pyridine-based urea receptors were studied by single crystal X-ray diffraction methods and revealed a rich conformational flexibility influenced by solvents. Whereas receptor L(1) in DMSO prefers an "S" conformation, receptor L(1) crystallizes in an "O" conformation from DMSO/CH(3)OH binary solvent system, and a "W" conformation in the ternary solvent mixture DMSO/toluene/1,4-dioxane. In the case of L(2), the molecule adopts an "S" conformation where water molecules are sandwiched between two molecules of L(2) to form a dimer. Similar to L(2), L(3) also forms a dimer where water molecules are sandwiched between L(3) molecules, which are capped with two molecules of DMSO. Such a capping DMSO solvate is lacking in the case of L(2). Taken together, these results demonstrate that the conformation of 2,6-bis(2-anilinoethynyl) pyridine-based urea receptors can be dramatically manipulated and tuned by the choice of crystallization solvents.
通过单晶X射线衍射方法研究了基于2,6-双（2-苯胺基乙炔基）吡啶的脲受体的构象，结果表明其构象具有丰富的灵活性，受溶剂影响。在二甲基亚砜（DMSO）中，受体L(1)倾向于“S”构象；在DMSO/甲醇（CH(3)OH）二元溶剂体系中，受体L(1)结晶为“O”构象；在三元溶剂混合物DMSO/甲苯/1,4-二氧六环中为“W”构象。对于L(2)，分子采取“S”构象，水分子夹在两个L(2)分子之间形成二聚体。与L(2)类似，L(3)也形成二聚体，水分子夹在L(3)分子之间，L(3)分子上还结合有两个DMSO分子。而L(2)则不存在这种由DMSO封端的溶剂化物。综上所述，这些结果表明，通过选择结晶溶剂，可以显著地控制和调节基于2,6-双（2-苯胺基乙炔基）吡啶的脲受体的构象。
