Synthesis and characterization studies of novel macrocyclic compounds with CH and NH donor groups
The dissertation focuses on the recent discovery in supramolecular chemistry of novel macrocyclic compounds with NH and CH donor groups. Chapter 1 provides a brief overview of the anions under study, supramolecular chemistry, the relevant other anion receptors, as well as previous findings involving the use of CH donor groups as functional building blocks. Chapter 2, as the major focus of this dissertation, describes a pyrrolyl-based triazolophane, incorporating CH and NH donor groups, which acts as a receptor for the pyrophosphate anion in chloroform solution. It shows selectivity for this trianion, followed by HSO₄− > H₂PO₄− > Cl− > Br− (all as the corresponding tetrabutylammonium salts), with NH−anion interactions being more important than CH−anion interactions. In the solid state, the receptor binds the pyrophosphate anion in a clip-like slot via NH and CH hydrogen bonds. Chapter 3 describes a pyrrole–based triazolium–phane which has been prepared through “click” chemistry in moderate yield. It displays a high selectivity for tetrahedral oxyanions relative to various test monoanions and trigonal planar anions in mixed polar organic–aqueous solvent media. It was also found that the binding affinity and selectivity of the macrocycle to the anions are solvent dependent. Several crystal structures were solved. They confirm that the cationic macrocycle ring binds pyrophosphate and phosphate anions in the solid state. Finally, chapter 4 describes a novel 1,3,4-substituted 1,2,3-triazolium salt found to function as an effective precursor for the synthesis of structurally characterized cationic silver(I) and ruthenium(II) carbene complexes of overall 1:2 ligand-to-metal stoichiometry. The Ag(I) complex crystallized in the form of an eight silver atom containing cluster, whereas the Ru(II) complex proved to be a discrete species and was found to be capable of initiating the ring-opening metathesis polymerization of norbornene upon activation with (trimethylsilyl)diazomethane.