Substituent Effects in Double-Helical Hydrogen-Bonded AAA-DDD Complexes
摘要:
AbstractTwo series of DDD and AAA hydrogen‐bond arrays were synthesized that form triply‐hydrogen‐bonded double‐helical complexes when combined in CDCl3 solution. Derivatization of the DDD arrays with electron‐withdrawing groups increases the complex association constants by up to a factor of 30 in those arrays examined. Derivatization of the AAA arrays with electron donating substituents reveals a similar magnitude effect on the complex stabilities. The effect of substitution on both types of arrays are modeled quite satisfactorily (R2 > 0.96 in all cases) as free energy relationships with respect to the sums of their Hammett substituent constants. In all, the complex stabilities can be manipulated over more than three orders of magnitude (>20 kJ mol−1) using this type of modification.
介绍了四个包含基础AADD氢键序列的自互补低聚物的设计和合成,并在溶液和固态下检查了它们的自缔合。两条链之间的分子识别对其组成杂环的取代高度敏感。用给电子和吸电子基团取代以及预组织的影响对所研究复合物的整体稳定性有很大影响。特别地,证明了关于在ADAD低聚物中的各个位置处的取代的宽范围(> 10 5 M -1)的稳定性。在最极端的情况下,测得的二聚常数(K二聚体≥4.5×10 7 M -1)与迄今为止报道的中性AADD阵列最稳定的同型二聚体相当。