A new class of phenanthridinium derivative has been isolated from the reaction of 2-bromoethyl-phenanthridinium bromide with a range of primary amines in excellent yields. The reaction pathway is unprecedented and proceeds via three cascade steps: nucleophilic attack of a primary amine on the iminium moiety of a heteroaromatic ring system and cyclization to form a five-membered ring, followed by hydride loss to yield a rearomatized dihydro-1H-imidazo[1,2-f]phenanthridinium derivative. A range of NMR phase transfer experiments were carried out to elucidate the mechanistic pathway, and the methodology has been further developed by means of a biphasic system using N-bromosuccinimide as a co-oxidizing agent. The method has also been extended to other N-heterocyclic cation derivatives such as quinolinium and quinazolinium.

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A new class of cytotoxic heteroaromatic cations is presented, based on the dihydro-imidazo-phenanthridinium framework (DIP), that have affinity for DNA and cytotoxicity toward cancerous cells. The DIP framework is particularly tunable due to the flexible synthetic methodology. Furthermore, the central moiety has proved to be very stable to hydrolysis and reduction compared to other phenanthridinium-based agents.

A new class of heterocyclic aromatic cation with novel physical properties has been constructed by an unprecedented reaction pathway that proceeds via five spontaneous steps to yield a 'synthon' that can be further derivatised by a final nucleophilic substitution step.