Pyrrole-2 - Carboxylic Acid Esters Synthesis And Crystal Engineering,

Supramolecular chemistry is the science studying on the intermolecular weak interactions and their assemblies,which may have special structures and functions.It has developed rapidly and become one of the challenging fields.Supramolecules by self-assembly via intermolecular hydrogen bonding interaction are a relatively new and fascinating area in supramolecular science.In this dissertation,we aim to use the supramolecular synthon I, centro-symmetric dimmers with pair of N-H…O hydrogen bonds between two pyrrole-2-carboxylate moieties,to direct and module the self-assembly.18 pyrrole-2-carboxylate derivatives have been designed and synthesized.The crystal structures of six target compounds have been characterized by the X-ray crystallographic studies.This dissertation consists of three parts.The origin,development and application of the hydrogen self-assembly and some examples of pyrroly self-assembly have been elaborated in the first introduction part.In the second part,the synthesis of eighteen target compounds has been introduced in detail.The best procedure of every step has been summarized. Thirty-six compounds have been synthesized and most of them have been characterized by ¹H NMR,MS etc.The crystal structures of six target compounds,3,10,19,20,23 and 24,have been reported in the third part.In the crystal structures of compounds 3,23,and 24, the expected supramolecular synthonⅠhas been observed.It indicates that the synthonⅠis robust enough and can been used in design and modeling the supramolecular structures.In the crystal structure of 10,new type hydrogen bonding motif,helical C₂²(10)chain,has been observed.It enriched the supramolecular synthon of pyrrole-2-carboxylate derivatives.In crystal structure of compound 19,the existence of OH disturbed the occurrence of synthonⅠ.19-19 dimer formed by using pair of N-H…O hydrogen bonds between pyrrole NH and Oxygen atom in hydroxyl group.It suggest that it should avoid the existence of strong hydrogen bond donator when using synthonⅠto direct the self-assembly.It was found that there is a lot of intermolecular non-conventional C-H…O hydrogen bonds in the crystal structures of 3,19 and 23.Meanwhile,some intramoleuclar C-H…O hydrogen bonds also exist in the crystal structures of 19 and 23.X-diffraction studies indicate that the length of intermolecular C-H…O hydrogen bond is shorter than the intramolecular hydrogen bonds'.At the same time,the angle of intermolecular C-H…O hydrogen bond is closer to the ideal angle than the intramolecular one.In other words,the intermolecular C-H…O hydrogen bond is more stable than the intramolecular one.