pH dependent conformational dynamics of substituted triazines

Abstract

Triazines appear as building blocks for macromolecules used in materials science and medicine. Triazines can be protonated under aqueous conditions, and it is hypothesized that pH changes the conformational dynamics of triazines in solution. Predicting the structure and dynamics in water as a function of pH requires reliable simulations of the rotational barriers and pKa values for different sites for protonation. We present the initial DFT methods and continuum solvent for pKa and rotational barriers of amines, ring nitrogens, and 2,4,6-triamino-1,3,5-triazine (melamine) derivatives. These (M062X/6-311++(2d,2p) in SMD continuum water) calculations provide consistent accuracy for tested systems, and results validate the initial hypothesis by showing that rotational barriers of acyclic amino groups change upon ring nitrogen protonation.