The color expression in Nature deserves the attention of scientists searching eco-friendly
solutions to substitute pollutant synthetic dyes used in industrial processes. Being natural pigments, anthocyanins represent an affordable alternative; unfortunately, the colored
structures in anthocyanins are only stable in very acidic conditions, forming colorless products as the pH increases, precluding a more widespread utilization of these compounds as
dyes. This has motivated significant research efforts focusing on the development of new
strategies toward color stabilization in anthocyanins and their application in formulations
with different pHs in the coloring industry. On the other hand, the colorless structures
are light-sensitive being responsible for the photochromic properties in some anthocyanins
and synthetic derivatives. The study of photochromic transformations between uncolored
and colored forms is important in the development of photochromic devices in the materials
industry. In this thesis, a deep physical-chemical analysis of some natural mechanisms for
color stabilization such as self-association, aggregation, and co-pigmentation was performed
in anthocyanins and synthetic derivatives, in order to understand how Nature rules the
expression of color. Some other methods based on supramolecular assemblies as host-guest
interactions and micelle inclusions were also studied for the stabilization of both, colored
and uncolored species, searching for the stabilization of color and improvement and application of the photochromic properties. Some results in natural anthocyanins indicate that
the inter and intramolecular interactions during their self-association and aggregation processes, as well as the number of acylated units, result crucial in the stabilization of color and
their water solubility. The co-pigmentation effect of the caffeine over the color stabilization
was evaluated in a systematic way, employing a developed new method to explain the higher
affinity of the co-pigment for the chromophores. The inclusion of anthocyanins and their
synthetic derivatives into host receptors as molecular clips, calix[n]arenes, and micellar
environments proved a high stabilization of the color along the pH scale. On the other
hand, the photochromic properties of some synthetic flavylium systems were explored; the
quantum yield of photoisomerization between uncolored and colored species was increased
by the complexation with cyclodextrin as a host. The pH and light-sensitive properties of
anthocyanins derivatives were exploited in the construction of a molecular timer controlled
by changes in the pH and a system able to control the dissociation of boronate esters by
photoisomerization
