Assessing the impact of increase in the number of hydroxyl groups on the microscopic behaviors of ammonium-based room temperature ionic liquids: A combined fluorescence up-conversion, fluorescence correlation and NMR spectroscopic study

•Microscopic behaviours of ammonium-based hydroxyl ILs with varying number of hydroxyl groups have been investigated.•FLUPs technique coupled with TCSPC technique have been used to capture the complete solvation dynamics of relevant RTILs.•Rotational and translational diffusion of Perylene and MPTS have been studied using TRFA and FCS techniques.•Self-diffusion coefficients of the cations of the RTILS have been estimated using PFG-NMR techniques.