Antimicrobial resistance (AMR) is a major global health concern that causes millions of deaths each year. There is an urgent need for novel antimicrobial agents with unique modes of action to combat the increasing instances of resistance. 1,10-Phenanthroline continues to be a useful ligand in the design of novel therapeutic agents. Two families of derivatised 1,10-phenanthroline ligands, the first with a phenanthroline core fused with an oxazine ring (phen-oxazine), and the second with the phenanthroline core fused with a pyridine ring (phen-pyrido) with varying lipophilicity were synthesised and characterised along with their respective Ag(I) and Re(I) tricarbonyl complexes. The Ag(I) complexes were found to exhibit fluxional behaviour in solution. Antifungal testing of the phen-oxazine ligands against Candida albicans showed a clear lipophilic effect; the MIC50 values decreased from > 60 μM (R=Me), to 43.3 μM (R=Pr), to 14.6 μM (R=Hex). Complexation of phen-oxazine to Ag(I) was shown to greatly enhance the antifungal effects; all complexes held fungal growth below 15% of the negative control experiment at all concentrations tested (60 – 15 μM). The uncoordinated phen-oxazine with a propyl sidechain and its Ag(I) complex were found to be well tolerated in vivo by Galleria mellonella larvae. The Re(I) tricarbonyl phen-oxazine complexes were found to form as a pair of diastereomers. Crystal structures were obtained for one diastereomer of the propyl derivative of the Re(I) phen-oxazine complex and of the corresponding Re(I) phen-pyrido complex. Both crystals presented as distorted octahedral fac-isomers. Irradiation of the Re(I) complexes with broad band light resulted in gradual changes in their UV-visible spectra consistent with a photochemical reaction, however, myoglobin assays did not provide evidence for CO loss upon irradiation. Cyclic voltammetry revealed that the Re(I) phen-pyrido complexes were more redox active than the corresponding phen-oxazine analogues. Synthesis of analogues Mn(I) tricarbonyl complexes of phen-oxazine and phen-pyrido was attempted but was not successful.