Nanoporous graphene (NPG) is unique in that it exhibits both electronic functionality as a tunable semiconductor and mechanical functionality as a tunable molecular filter membrane. Combining these properties into a single atomically-thin, mechanically robust platform makes NPG an excellent candidate for electronically active nanosieve applications such as sequencing, sensing, ion transport, gas separation, and water purification. The incorporation of nanoscale pores into a sheet of graphene allows it to switch from an impermeable semimetal to a semiconducting nano-sieve. The performance of nanoporous graphene is highly dependent on the periodicity and reproducibility of pores at the atomic level. The utility of this material, however, hinges on the ability to induce periodic, atomically-precise nanopores and to tailor their precise dimensions and electronic properties. Top-down lithographic approaches have proven to be challenging due to poor structural control at the atomic level and because they typically produce random, imprecise pores within a material that remains semi-metallic. A disadvantage of the few reported bottom-up synthesized NPGs is that the constituent nanoribbons are wide gap semiconductors. Using a bottom-up synthesis, UC Berkeley researchers have created a fully conjugated nanoporous graphene through a single, mild annealing step following an initial polymer formation. They found emergent interface-localized electronic states within the bulk band gap of the graphene nanoribbon that hybridize to yield a dispersive two-dimensional low-energy band of states. The localization of these 2D states around pores makes this material particularly attractive for applications requiring electronically sensitive molecular sieves.