Chemical AI in the Limelight: The Contribution of Photochromic Materials and Oscillatory Chemical Reactions

Chemical Artificial Intelligence (CAI) is the burgeoning research field devising chemical systems in "wetware" (i.e., in liquid solutions) to mimic biological intelligence competencies. UV-visible radiation is valuable for maintaining those systems out-of-equilibrium, prompting them to respond to optical and other physicochemical signals and probing their evolution. As it occurs in all the kingdoms of life, photochromic compounds play a relevant role. Several living beings exploit photochromic switches for variegate responses to the features of the environmental light. This work proposes a plausible justification by evidencing how each photochrome can be conceived as a trivial form of Markov blanket and implement (i) forward, (ii) final, and (iii) circular causalities. Furthermore, photochromic materials are appropriate for processing Boolean and fuzzy logic, exploiting their chemical reactivity, chaos, and quantum computing. Finally, photochromic molecules and oscillatory chemical reactions are promising ingredients for developing neuromorphic engineering in wetware based on optical signals. CAI inspires the design of adaptive, active, and autonomous chemical systems, which help humanity to colonize the molecular world against diseases, pollution, and poverty.