Polyphosphate gel/methyl orange supramolecular composites

The aims of this work were to investigate theoretically the optical properties of methyl orange (MO) and the synthesis of new supramolecular composites based on the incorporation of this dye in an aluminum polyphosphate gel network. The theoretical methodology was based in semiempirical (AM1 and INDO/S-CI) and ab initio (3-21G*) methods. Our results reveal the existence of different electronic patterns for the acidic and basic forms of these molecules. Also, we present a theoretical spectroscopic study for the molecules including interactions with water molecules. MO was successfully incorporated in its acidic form within the host matrix, leading to pink–red transparent selfstanding films. The dye could be converted to its basic form upon exposure to ammonia vapor. The spectrum of MO basic form within the gel network differs from its behavior in aqueous solution. 2003 Elsevier B.V. All rights reserved.