Self-assembling behavior of pyrimidine analogues: Unveiling the factors behind morphological diversity.

Studying the self-assembly of uracil derivatives has great importance in biochemistry and nanotechnology. Now, in order to architect unique and interesting nucleobase nanostructures, herein, we report a simple, yet robust uracil moiety based platform which is potentially capable to self-assemble into fibrils. The system is validated using eight uracil moiety derivatives and the effect is examined via fluorescence lifetime imaging microscopy (FLIM), field emission scanning electron microscopy (FESEM), steady state DCM fluorescence and fluorescence correlation spectroscopy (FCS). FLIM and FESEM give qualitative information regarding the fibril formation of different morphologies including string, rod, flower, needles etc. Steady state DCM fluorescence and FCS establish a quantitative estimation of the extent of fibril formation. The involvement of hydrogen bonding interaction between NH and CO groups in the fibrillar growth of 5-IU is evoked from the crystallographic study. Again, the key role of different functional groups behind the formation of fibrillar network is investigated through blocking the COO- group of orotic acid with lanthanides. Finally, esterification and N,N'-dimethylation exquisitely explore the role and priority of different groups in the fibril formation of pyrimidine analogues. The results may be useful for understanding the processes of self-assembly of the uracil derivatives and the rationalized design of the uracil based supramolecular structures with specific properties.