All these compounds display the typical cyanine-like UV-vis absorption with an intense and sharp transition with a vibronic shoulder. TD-DFT calculations allowed to fully rationalize the optical properties (absorption/emission wavelengths, luminescence quantum yields). Interestingly, due to the tetrahedral shape of the P-atom, the optical properties are independent of the counterion, which is in marked contrast with N-analogs, which enables predictive engineering of the phosphacyanines regardless of the medium in which they are used.