A current challenge in material sciences is to keep rigorous control over increasingly complex assembly of active building blocks in extended porous frameworks, while retaining predictive insight in their ultimate performance. The ability to introduce various active building blocks into one porous framework has already allowed the modulation and prediction of physical and chemical properties, improving the capacity to tune fundamental properties including hydrophobicity, 2 porosity, optical response, and catalytic activity. The capacity to extend the control over opto-electronic properties to the molecular-level, while retaining the control over other physico-chemical and structural properties, becomes key in the context of materials applications to renewable energy utilization; the capacity to control opto-electronic properties will in turn drive the materials photocatalytic performances.