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This contribution reports, through a combined thermogravimetric analysis, differential scanning calorimetry, UV–vis, powder X-ray diffraction, and Rietveld refinement analysis, on the stimuli-responsive chromic properties of a substituted Zn(salmal) Schiff-base Lewis acidic complex with unique and distinct thermo- and vapochromic characteristics. The solid complex obtained in air or by evaporation of the solvent from their THF solutions shows a marked thermochromism associated with a phase transition, unusually triggered by the reversible desorption/adsorption of one lattice water molecule. In contrast, the anhydrous solid, achieved from THF solutions of the complex by evaporation of the solvent under anhydrous conditions, behaves very differently as it does not show any absorption of water or thermochromism and exhibits varied vapochromic properties. Detection of volatile organic compounds having Lewis basicity is demonstrated by using the anhydrous solid or the related cast films on glass or paper substrates. In both cases, a marked vapochromism is observed upon exposure to vapors of various volatile species and involves well-defined optical absorptions and naked-eye color changes, also allowing the discrimination of primary aliphatic amines. Vapochromic behavior with the formation of stable, stoichiometric adducts is also demonstrated for both the solid obtained in air and the anhydrous solid or for the related cast films after exposure to vapors of pyridine.

A gas-phase route such as molecular layer deposition has been applied for the first time to create a monolayer of metalorganic Eu(III) molecules on NiO oxide layer. The surface of the as-deposited NiO layer is activated using H2O/O2vapors, and then functionalized by anchoring molecules of the Eu complex working at different temperatures to favor the chemisorption process. The effects of the activation process and of the MLD temperature on the chemisorption of the Eu complex were evaluated through in-depth X-ray photoelectron and luminescence spectroscopy studies. These analyses allowed to define the stoichiometry of the Eu moiety chemisorbed on the surface and the optimization of an impressive strategy to the synthesis of hybrid metalorganic/inorganic systems. The hybrid system's luminescence properties have proved the monolayer's energy conversion phenomena and produced further information about the local environment around the Eu(III) anchored as a complex on the NiO surface.