The vapochromic and chemiresistive properties of a nanofibrillar molecular material composed of an amphiphilic Zn(II) Schiff-base complex, 1, are explored with the aim to obtain new materials with multifunctionalities. The solid 1 is characterized by the existence of two stable dimorphs, both exhibiting a nanofibrillar morphology. The thermal annealing of the ground solid 1 induces an irreversible lamellar-to-square columnar structural phase transition, as assessed by differential scanning calorimetry and X-ray diffraction analysis. When exposed to vapours of a Lewis base, spin coated films of the square columnar dimorph exhibit a marked change both of the optical absorption spectrum and of the resistance, because of chemisorption of the Lewis base with formation of 1Lewis base adducts. The chemisorbed material is easily restored by thermal heating (150 °C) inducing desorption of the Lewis base. The changes …