Encapsulation of vanillylamine by native and modified cyclodextrins: Spectral and computational studies

Inclusion complex formation of vanillylamine (HMBA) with α-, β-, hydroxyl propyl α- and hydroxyl propyl β-cyclodextrins were studied by absorption, steady state fluorescence, time resolved fluorescence, FT-IR, 1H NMR, molecular modeling methods. The study revealed that HMBA formed 1:1 complex with all the four CDs. Nanosecond time-resolved studies indicated that HMBA show single exponential decay in water whereas biexponential decay in CDs. Thermodynamic parameters and binding affinity of complex formation of all the CDs were determined and discussed. It was found that van der Waals interactions are mainly responsible for enthalpy-driven complex formation of HMBA with CDs.

► HMBA forms 1:1 complex with α-CD, β-CD, HPα-CD and HPβ-CD.
► CH2NH2 group present in the inner part of the CD nano-cavity.
► Biexponential decay was observed in the nanosecond time-resolved fluorescence.
► ΔG, ΔH, ΔS, and HOMO–LUMO orbital calculations confirm the better stability of the inclusion complex.
► Nanomaterial structure of the inclusion complex was different from guest and host.