The photoexcited hydrogen bonded complex molecule shows low radiative rate constant as compared to its luminescent COF part. The S1 hydrogen bond is strengthened. The MOs analysis demonstrated that the electron density distribution was mainly located on formaldehyde (guest molecule) in LUMO while the HOMO showing the distribution on pyrene unit of the COF. All other parameters also in support of quenching process but I couldn’t able to illustrate the specific deactivation pathway for this noncovalently bonded complex molecule. Can anyone will guide me, please?