Abstract
Nanostructured materials have become the central subject of materials research during the last decade in the past 20th century owing to the novel electronic, optical, and catalytic properties observed in such materials. The unusual properties of these nanostructured materials can be attributed to two main microscopic effects: quantum confinement and electronic confinement. These two effects have dominated the variations of molecular properties in a wide variety of nanostructured materials, ranging from inorganic compounds to organic molecules. The recent advances have focused on host-guest complex systems that have resulted in a deeper understanding of the changes in electronic structures when being confined. In this article we cover some of the key advances in the study of quantum and electronic confinement effects, especially in host-guest systems.