The constant search for materials with new and improved properties has led to a variety of investigations into molecular materials and a growing interest in the exploration of molecular-based functional materials research. Molecular functional materials are made up of molecules that could perform a specific function or task at the molecular level. This increasing interest in the search for new molecular materials based on pure organic and metal-organic systems mainly stems from the versatility of materials development through rational design studies and elucidation of the structure-property relationship at the molecular level. Organic and metal-organic molecules can serve as versatile building blocks for molecular-based functional materials as they can be rationally engineered and prepared, and their properties are tunable with a proper understanding of structure-property relationships. In this presentation, a number of metal-ligand chromophoric complexes, coordination compounds and molecules will be described. Through rational design and various strategies, these molecular materials may find potential applications and functions as efficient triplet emitters for small-molecule and solution-processable organic optoelectronics, and as materials for memories, chemosensing and biological assays.