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The use of benzophenoxazine dyes such as Nile red and Nile blue in various applications has received increasing attention in recent years. Due to the limitations of using the two dyes in aqueous media because of their poor solubility, extensive efforts have been made to synthesize new benzophenoxazine analogues. Therefore, the first part of the work aims to characterize modified structures of benzophenoxazine derivatives as well as Nile red and Nile blue using spectroscopic techniques. The optical properties of the dyes involve the determination of molar absorptivity and quantum yield values as well as photostability studies. The absorbance and emission wavelengths are in the visible and near-infrared region of the electromagnetic spectrum which is the most useful region for bioanalytical applications due to the reduced autofluorescence from biomolecules. The first part also includes the interactions between benzophenoxazine derivatives and human serum albumin. The affinity of the dye to the protein is hydrophobicity-dependent, but other parameters such as steric hindrance and electrostatic interaction play a role too as confirmed by binding constant values. Detection of fingerprints is considered one of the most valuable pieces of evidence in forensic investigations. The second part of the work aims to use benzophenoxazine derivatives for fingerprint detection on porous surfaces. The factors affecting the ability of Nile red and Nile blue derivatives to develop luminescent and visible fingerprints with good background contrast are discussed. The second part also contains the application of silica nanoparticles encapsulating some benzophenoxazine derivatives as well as fluorescein isothiocyanate as fingerprint reagents. The efficiency to develop fingerprints is governed by the nature of the encapsulated dye and organosilicate precursors.

The phenoxazine core has been explored in the development of chromophoric systems that have seen use as fluorescent probes and therapeutic agents in combating illnesses of many forms. This thesis reports the synthesis and evaluation of some novel phenoxazine and benzo[a]phenoxazine analogs. Phenoxazinium are charged lipophilic molecules and the recent resurgence of π-Delocalized Lipophilic Cations (DLC) hypothesis in the combat against protozoan illnesses has prompted focus on the synthetic exploration of the derivatization of their architectures in medicinal chemistry. The principle aim of these modifications were to synthesize a focused library of systematically modified analogs catering to the enhancement of related “drug like” properties found throughout the literature of their development as antimalarials.

Nile red and Nile blue are intensely colored fluorescent dyes from the benzophenoxazine family. Modification of the donor amine with varying alkyl substituents was achieved with the principle aim being to investigate differences, both optical and physical, between dye scaffolds outfitted with secondary amines versus tertiary amines. These changes to the dyes’ architectural framework gave holistic effects to the bulk molecule by modulating hydrophobicity, optical properties, and protein binding constants to human serum albumin.