CONTENTS

A variety of devices and sensors based on phosphorescence or photoexcited state quenching of porphyrin molecules (platinum(II), palladium(II), zinc(II), metal-free, etc.) dispersed in oxygen-permeable polymer film or directly immobilized onto solid surface via the chemical or physical adsorption are developed to measure oxygen concentration on the solid surface. Oxygen-sensing systems are classifi ed into four types; (1) phosphorescence intensity change, (2) phosphorescence lifetime change, (3) change of lifetime of photoexited triplet state and (4) intensity change of absorption of photoexited triplet state. In this review the properties of various optical oxygen-sensing devices using porphyrin and sen sing system are introduced.

Metalloporphyrins are characterized by manifold of interactions of different strength and selectivity. These interactions can be differently captured by mass (quartz microbalance) and surface potential transducers (field effect transistor). Field effect transistors preserve the interactions magnitude scale and maintain the original selectivity of the molecular recognition system, while the quartz microbalances tend to smooth the differences between the interaction mechanisms in volved.

Langmuir-Blodgett films of three different metalated tetrapyrrolic macrocycles have been deposited onto the piezoelectric crystals of a flow-through quartz microbalance. The sensing performances of the modified gold electrodes have been investigated by monitoring the frequency variation induced by the presence of several toxic phenols. Floating films at the air-water interface have been thoroughly characterized by UV-visible refl ection spectroscopy and brewster angle microscopy.

Thin films of meso-octaethylporphyrinogen with different thickness were deposited on suitable substrates by Langmuir-Blodgett deposition technique in order to realize optical-sensitive active layers using Surface Plasmon Resonance (SPR) technique as transduction methodology, for the detection of alcohol vapors such as ethanol, methanol and isopropanol.

The binding of halides and alkali metal cations with porphyrin hosts is reported. The halide ions are complexed with diprotonated porphyrin macrocycle with high affinity and the stable complexes of 1:1 and 1:2 structures with halide ions are formed. The alkali metal cations are trapped with mono-meso-arylporphyrins containing a conformationally mobile complexing polyether fragment on the benzene ring with a terminal pyridine ring. The five-membered polyether chain was shown to provide very high binding selectivity for potassium over lithium or sodium.

Radical bisphthalocyanines are one of the most interesting sensing materials. Bisphthalocyanines thin films have been successfully used as resistive, optical, mass and electrochemical sensors and they have also been applied in electronic noses and electronic tongues.

Different corrole derivatives have been exploited as ionophores for the development of solvent polymeric membrane ion-selective electrodes (ISEs). The selectivity and the working mechanism of developed ISEs have been investigated in detail. Due to their high sensitivity to the background solution pH, it is difficult to obtain highly-selective ISEs using free-base corrole, while Mn and Cu and Fe corrole derivatives are shown to be highly selective correspondingly for chloride ion and hy drophilic anions detection.

In this paper, the effect of coating parameters on sensing properties and sensing mechanism are reviewed. The authors proposed an alternative way to achieve optimal sensor performance: liquid crystalline Pcs forming self-ordered thin films of defined area and thickness simply by heating the sample over the phase transition temperature and synthetized mesomorphic and functionalized phthalocyanines, to develop sensors based on mass-sensitive transducers (quartz crystal microbalance, QCM).

Columnar liquid crystal porphyrin compounds have been deposited onto the gold pad of quartz crystal microbalances (QMBs). The sensitivities of the resulting sensors have been measured with respect to volatile organic compounds (VOCs) and have been found to be of interest for future applications. The results show a strong influence of the length of the side alkyl chains, but the thermal history of the coated film also affects the measured properties.

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