Synthesis and Characterisation of Sudan Red-G/Cyclodextrin Doped ZnO Nanocrystals

Sudan Red-G/cyclodextrin-doped zinc oxide nanocrystals are synthesized and characterized by UV-visible, fluorescence, FTIR, DTA, XRD, SEM, and TEM methods. Solvent and cyclodextrin studies confirm the existence of the azo-hydrazo tautomer in the SRG molecule. The ground and excited state absorption wavelengths of SRG are similar to Red G, Sudan I, and Sudan II. The dipole moment, internal energy, free energy, enthalpy, entropy, and the HOMO-LUMO energy levels of SRG, α-CD, β-CD, SRG/α-CD, and SRG/β-CD are determined using the PM3 method. SRG's horizontal bond length is higher than the α-CD and β-CD cavity size, only a partial inclusion of the SRG molecule occurs in the CD. Absorption and emission spectral shifts are largely varied when SRG/CD doped on ZnO. Compared to SRG and ZnO/β-CD, the ZnO/SRG/β-CD nanocrystals showed significant differences in the FTIR, DTA and XRD peaks, indicating that SRG and β-CD were successfully doped onto the ZnO nanoparticles. TEM morphology supports the formation of nanocrystals in the SRG/CD doped ZnO. The nanocrystal sizes are analyzed using TEM-EDS and XRD techniques.