A new sandwich-type diphthalocyanine as a potential optical transducer forNO2 detection

Bis(phthalocyaninato)titanium(IV) (Ti(Pc)(2)), a sandwich-type metal diphth alocyanine, is used as a chemical transducer for the optical detection of n itrogen dioxide. The optical properties of this chemical transducer after i ts immobilization on controlled pore glass (CPG) by a casting from a Ti(Pc) (2) solution in alpha-chloronaphthalene are described. This compound is cha racterized by three well-defined absorption bands in the visible region (la mbda = 506, 675 and 720 nm) which undergo spectral changes in the presence of nitrogen dioxide. Two different optodes were manufactured and characteri zed. A plastic flat reflector is used as a solid support placed in front of an optical fibre bundle, and Ti(Pc)(2) is immobilized on CPG that was prev iously embedded in the plastic reflector either by casting or by sublimatio n. The characterization of the developed optodes in terms of sensitivity, r eversibility and response time is described. (C) 1998 Elsevier Science S.A. All rights reserved.