Stimuli-responsive, thixotropic bicomponent hydrogel of melamine–Zn(II)-orotate complex.

Zinc(II)-orotate complex (ZnOA)has been synthesised, and it is used to produce supramolecular complex with melamine (M) at 1:1 molar ratio. During sonication for 5–6 min, the supramolecular complex is transformed into a bi-component hydrogel (S-gel). The spectroscopic tools such as FTIR and UV–vis spectra suggest that the H-bonding interaction betweenMandZnOAproduces a supramolecular complex which further forms J-aggregates during gelation. The circular dichroism spectra indicate the change in ellipticity with temperature that arises from the molecular dissymmetry during stacking of theZnOAMcomplexes. The microscopic images indicate that the hydrogel network is formed with short helical nano-fibres. The energy-minimised structure ofZnOAMcomplex exhibits a well-defineddvalue of 11.3 Å obtained from X-ray scattering of the xerogel. The frequency-dependent rheological experiment (storage modulus (G′) is greater than loss modulus (G″)) characterises it as a gel. The gel shows thixotropic and stimuli-responsive behaviour. [ABSTRACT FROM AUTHOR]