Synthesis, Structure And Property Of Functionalized Heteracalixaromaticsand Corona[n]arenes

Supramolecular chemistry studies non-convalent bond interactions and molecular assemblies with focus on host-guest systems.Novel and functional macrocycles have become one of the main driving forces pushing forward the development of supramolecular chemistry.Heteracalixaromaticshave attracted tremendous attention recently and play an important role in conformational regulation,molecular recognition and self-assembly,etc.This dissertation mainly focuses on the selective aromatic electrophilic substitution reactionof azacalixpyidines,toprovide plenty of functionalizedheteracalixaromatics.Changing the chemical bond connectivities,we aimed tosynthesisa new class of functionalizedmacrocyclic host molecules,namelycoronarenes and investigate theirmolecular recognition properties.Under optimized conditions,the selective formylation,nitration and bromination on the azacalixpyridines were achieved.After analyzing the crystal structure,we found the substituent groups greatly influenced the conformation of macrocyclic backbone,the electronic configurations and conjugation with their adjacent aromatic rings.Taking the advantage of close proximity of aldehyde groups in 1,3-alternate di-and tetra-formylated azacalixpyridines,the McMurry reductive coupling reaction of carbonyls was accomplished to yield unique semi-cage molecules.With hydroquinone and diethyl 2,5-difluoroterephthalate as the starting materials,aromatic nucleophilic substitution reaction can occur smoothly.Using“3+1”and “3+3”fragment coupling strategy,ester-substituted On-corona[n]arenes were synthesised.After reduction and etherification,methoxymethyl-substituted On-corona[n]arenes were prepared.Fluorescence titrationdemonstrated that they formed 1:1 complexes with fullerenes C₆₀ and C₇₀ in toluene with an associate constant up to?2.14±0.07??10⁵ M^-1.With 2,5-dimethylbenzene-1,4-diol as a dinucleophilereagent,2,5-dibromopyrazine as a dielectrophilic reagent,O-corona[n]arene[n]pyrazines were synthesised through“3+1”and “3+3” fragment coupling strategy;Applying2,5-dibromopyrazine as the starting material,we haveachieved N-corona[8]pyrazine through a“3+1”Pd-catalyzed fragment coupling method.These pyrazine-containedcorona[n]arenes formed 1:1 complexes with fullerenes C₆₀ and C₇₀ in toluene with an associate constant ranging from?1.14±0.04??10⁴M^-1 to?2.21±0.04??10⁵ M^-1;N-corona[8]pyrazinewas able to bind Fe³⁺?Co²⁺?Ni²⁺?Cu²⁺?Zn²⁺and Hg²⁺in a mixture of acetonitrileand chloroform?9 : 1?with an associate constant up to?1.06 ±0.05?× 10⁷ M^-1.In summary,functionalized azacalixpyridines were synthesised through aromatic electrophilic substitution reactions.The products provide us with a platform for the fabrication of sophisticated macrocyclic molecules.We haveachieved the synthesis of new functionalized corona[n]arene.Utilizing pyrazine units,O-or Ncorona[n]pyrazines were constructed.These new corona[n]arenes are strong macrocyclic host molecules able to form complexes with fullerenes C₆₀ and C₇₀.Thepyrazine-containedN-corona[8]pyrazineinteractsstrongly with severaltransition metal ions.