Jozef Hodyl PhD Thesis - Theses - Flinders University

an aromatic ring centroid, F(2A) ... C(3C) was 2.93Å, whereas the BF 4-... Cp* and BF4-... arene distances for the anions outside the calixarene cavity were more than 3.10Å.It was found that the metal ions were essential for inclusion of BF 4 - to occur. 921.3.5 Tetraaza based Molecular ReceptorsThe number of studies involving tetraazamacrocycles has steadily increased over thelast few decades as these molecules show considerable ability in complexing metalions and also because their functionality can be diversified through their reactivenitrogen atoms.Undeveloped tetraazamacrocycles suffer one drawback, which is their inability toenclose metal ions with coordination numbers greater than four. Nevertheless, byincorporating pendant donor groups capable of metal ion coordination within theirframework this obstacle can be overcome. The chemistry of tetraazamacrocyclesappended with pendant donor groups has been extensively explored in recent times90, 93-103and instances within the scientific literature are abundant.It is well known that appending pendant donor groups at the periphery oftetraazamacrocycles leads to the retention of the chemical properties inherent in boththe macrocycle and the pendant arms. 104 As tetraazamacrocycles can be modified ateither their carbon skeletons or their secondary amines the chemistry of both hasbeen widely investigated. 105-107 However, N-substitution has proven to be much morefacile and therefore studies in this area predominate. 108-111Many of these studies have focussed on the chemistry of 1,4,8,11-tetraazacyclotetradecane (cyclam), 20, first synthesised by van Alphen, 112, 113 which,for the purpose of this work, is unsuitable in that substitution with four pendant armsand subsequent metal coordination will generally cause the cyclam complex to18