CROWN-ETHER LUTETIUM BISPHTHALOCYANINE LANGMUIR-BLODGETT-FILMS AS GASSENSORS

The gas adsorption and electrochromic properties of Langmuir-Blodgett films of octa-(15-crown-5)-lutetium bisphthalocyanine (CR-Pc(2)Lu) are reported. Films of CR-Pc(2)Lu were sensitive to electron donor and el ectron acceptor gases as well as tobacco smoke. The adsorption was tra ced using electronic absorption spectroscopy. The presence of crown et her groups on the phthalocyanine ring increased the sensitivity of the films to oxidizing gases. Stable red films were prepared using 0.01 M HCl as a subphase. Red films were also obtained by chemical oxidation . The use of previously oxidized LB films as the active layer highly i ncreases the sensitivity of the proposed sensor towards electron donor gases. The possibility of discriminating between the main and the sid e streams of the tobacco smoke, as well as the sensitivity to increasi ng amounts of smoke, were studied.