Achieving Complexity at the Bottom: Molecular Metamorphosis Generated by Anthocyanins and Related Compounds

Abstract

The concept of molecular metamorphosis is described. A molecule (flavylium cation) generates a sequence of other different molecules by means of external stimuli. The reversibility of the system allows for the flavylium cation to be recovered by other external stimuli, completing one cycle. Differently from supramolecular chemistry, molecular metamorphosis is not a bottom-up approach. All events occur at the bottom. The procedures to characterize the kinetics and thermodynamics of the cycles are summarized. They are based on direct pH jumps (addition of a base to the flavylium cation) and reverse pH jumps (addition of an acid to equilibrated solutions at higher pH values). Stopped flow is an indispensable tool to characterize these systems. The following metamorphic cycles will be described to illustrate the concept: (i) introducing the flavanone in the metamorphic system and illustrating the concept of a timer at the molecular level; (ii) response of the flavylium-based metamorphosis to light inputs and the write-lock-read-unlock-erase molecular system; (iii) a one-way cycle of direct–reverse pH jumps; (iv) interconversion of the flavylium cation with 2,2′-spirobis­[chromene] derivatives; (v) 6,8 A-ring substituent rearrangements.

Multiple molecular logic gate arrays in one system of (2-(2′-pyridyl)imidazole)Ru(ii) complexes and trimeric cyclophanes in water

“…It is a pleasure to note that remarkably complex networks have been constructed from photo-, pH-, thermal-and host-responsive ayylium salts. 132,133 The behaviour of some of these also correspond to various logic gate arrays. Peptide reaction networks are similarly complex and amenable to incorporation within logic schemes as well.…”

Purple Rehmannia: Investigation of the activation of R2R3‐MYB transcription factors involved in anthocyanin biosynthesis

“…In recent years, there has been a growing interest in food containing antioxidant ingredients. Anthocyanins, the largest group of flavonoids, are natural pigments with a flavylium cation (AH + ) form, which is directly related to anthocyanin's antioxidant capacity (Basílio et al, 2021). Free radicals, including reactive oxygen species, and/or reactive nitrogen species, are required for the proper performance of the human body and its organs (Tena et al, 2020).…”