Abstract: Metal organic frameworks (MOFs) are hybrid solid state materials composed of metal ions or clusters connected by organic molecules to form crystalline microporous networks. Their diversity in chemical makeup and tunable, permanent porosity make MOFs attractive candidates for traditional adsorption-based applications such as chemical separation and storage. Efforts to engender redox or photoredox properties offer new opportunities for applications that rely on MOF conductivity, stable electron transfer and/or long-lived charge separation such as resistive sensors, electrochromic devices, and single site electro- or photocatalysis. Synthetic strides in developing frameworks with these properties have, however, far outpaced the progress in advancing the fundamental understanding of their electronic structure and photophysics. Consequently, there are often significant ambiguities in the structure/function relationships that give rise to their utility. In our research, we use a targeted set of spectroscopy methods to make those connections by producing molecular level understanding of observed MOF behavior. Specifically, the talk will focus on two types of photoredox active MOF systems. In the first part, a set of Ti-based redox active frameworks will be introduced and our efforts to elucidate the nature and dynamics of their charge-separated excited states using X-ray transient absorption spectroscopy will be presented. In the second part of the talk, I will focus on a series of porphyrin-based MOFs that demonstrate electron donor-acceptor behavior upon post synthetic introduction of fullerene guest species. For this series, steady state and time-resolved optical spectroscopy methods help elucidate the binding location/strength and photo-induced charge transfer dynamics and in these host-guest systems.