Optical cycling center (OCC) is a chromophore moiety that supports electronic transitions closed for electronic and vibrational decay to other channels. It means that the excited state should decay primarily to the ground electronic state. The transition should also be * Electronic address: krylov@usc.edu closed at the vibrational level, such that the excited-state decay populates primarily the ground vibrational state. In this case the system can be subjected to repeated absorptionemission cycles without exciting molecular vibrations. By tuning the photon energy to be slightly below the electronic transition energy, each cycle results in slowing the translational motion of the system. This is the essence of laser cooling. The lower-energy spectral features, such as rotational and fine structure, must also be considered, but it is the closure on the vibronic (vibrational and electronic) level that is the chief prerequisite for optical cycling. The excited electronic state must also be short lived (lifetime <10-100 µs) to afford a rapid photon scattering rate necessary for effective laser cooling (this condition, however, is not critical for working with cations 1 ). These requirements for molecules suitable for laser cooling are well known from earlier studies. Potential applications of laser-coolable species include quantum computing and sensing, as well as precision measurements of fundamental physical constants. Charged particles are particularly attractive for experimental applications because they can be controlled by electric fields, motivating intense experimental and theoretical research in this area. Heavy molecular ions have been investigated as promising platforms for precision measurements. In charged molecular species, an OCC is useful for system preparation and measurement. Much experimental and theoretical effort has been focused on the SiO + cation. Prospective advantages in state control motivate an active search for molecular ions with a large ground-state dipole moment and a splitting of the ground state into opposite parity states in the radio frequency range . A closed optical cycle with a radiative lifetime of approximately 110 µs was predicted for the AcOH + cation. Computational studies have shown that because of high electronic transition energies RaF + and RaH + cations are not well suited for laser manipulations. Favorable vibrational branching ratios were reported for a transition of TlF + lying in the UV region. In the context of precision measurements, highly charged heavy cations offer additional benefits. In this domain the PaF 3+ cation was identified as a promising candidate for cooling. The prospects of laser-cooling anions have been discussed. Anions could afford sympathetic cooling of other negatively charged particles. However, in contrast to neutral and cationic species, which support many bound excited states, anions rarely have bound excited states. Among promising exceptions are C - 2 and BN -, which are isoelectronic to SiO + . Molecular anions of alkali metals were also investigated computationally , how-ever, the authors were not able to establish whether their electronic states were bound or metastable with respect to electron detachment.