The CaO-group can function as an OCC because it supplies the molecule with an access to an electronically excited state that spontaneously decays almost exclusively to the molecular (electronic and vibrational) ground state . Other quantum functional groups suitable for laser cooling, such as SrO-and YbO-, have also been identified . One-thus-far only hypothesized but exciting-possibility is to use quantum functional groups, such as CaO-OCCs, for precise optical sensing of chemical events. For example, it would be desirable to have an optical reporter that can detect a chemical change, such as a conformational change or a chemical reaction, in a part of the molecule distant from the reporter. Because OCCs are electronically isolated from the rest of the molecule by with a single unpaired electron (CaOH, pAB) are well described by EOM-EA-CC (EOM-CC for electron attachment). EOM-EE-CC (EOM-CC for excitation energies) describes excited states of closed shell molecules (AB), but it can also be used for open-shell species such as pAB. EOM-DEA-CC (EOM-CC for double electron attachment) and EOM-SF-CC (EOM-CC with spin-flipping excitations) are the preferred methods for diradicals (bpAB) . The paper is organized as follows. The next section provides details about the computational approach. In section III we review the electronic structure of the prototype moieties (AB, Ca-OH) and then characterize the electronic states of the pAB and bpAB. We focus on the three questions: (1) How the states of the scaffold are impacted by the OCC? (2) How the states of the OCC are impacted by the scaffold? (3) Can we employ the OCC as a spectroscopic probe of the isomerization reaction? We then discuss preliminary results of the synthetic efforts and outline future directions.