Functionalized single walled carbon nanotubes (SWNTs) have potential application in fabrication of novel electro-optical devices and sensors. SWNTs are mostly studied as dispersed colloidal solution in non-aqueous solvents. These kinetically stable dispersion help us to understand inter-molecular interactions, their solubility and rate of aggregation. In this present work we determine the stability of SWNTs dispersion in the presence of inorganic and ruthenium based optically active coagulants. The stability is discussed using classical DLVO theory, conventionally used to understand colloidal solutions. These long range molecular forces in solution drives individual building blocks into supramolecular assemblies.Moreover novel phenomena of photon enhanced aggregation in these functionalized SWNT are discussed. We believe that the nanotube quenches charge from the ligand after the complex has been optically excited.Photon induced effects on the charge transport are signifying "Optical gating" is shown in these fabricated SWNT field effect transistors.