Affinity Control of Inorganic/Organic Hybrid Materials toward Molecule for Sensors

Abstract

In order to control the affinity control of inorganic/organic hybrids toward a molecule for the application to sensors, the solid acid-base properties of inorganic/organic hybrids were generated by the incorporation of inorganic components other than siloxanes. The solid acid-base strength was varied from basic (H₀=9) to acidic (H₀=1) regions by the incorporation of various inorganic components into methylsiloxane-based inorganic/organic hybrid. The basic methylsiloxane-based inorganic/organic hybrid containing a Ca inorganic component tended to adsorb an acidic molecule of NO₂ and the acidic methylsiloxane-based inorganic/organic hybrid containing a Ti inorganic component tended to adsorb a basic molecule of pyridine. The Al-containing methylsiloxane-based inorganic/organic hybrid with acid-base strength between the Ti- and Ca-containing hybrids adsorbed both a basic molecule of pyridine and an acidic molecule of NO₂. On the basis of the affinity control by verify the solid acid-base strength, the inorganic component derived from Nb(OC₂H₅)₅ was incorporated into the aminopropylsilane-based inorganic/organic hybrid to weaken the strong basicity resulting from amino groups. The aminopropylsiloxane-based inorganic/organic hybrid containing an Nb inorganic component resulted in a detectable change in the optical properties and acted as a reversible sensitive film toward NO₂ for an optical sensor.