Zdeněk Mička

Quantum yields of singlet oxygen of metal complexes of meso-tetrakis(sulphonatophenyl) porphine

Abstract The iodide method and the method of bleaching of p -nitroso- N , N ′-dimethylaniline (RNO) were used to measure the quantum yields of singlet oxygen from the tetrasodium salt of meso-tetrakis(4-sulphonatophenyl) porphine (H2TPPS4) and its water-soluble metal complexes with divalent metals, Ag(II)TPPS4, Cd(II)TPPS4, Co(II)TPPS4, Cu(II)TPPS4, Mg(II)TPPS4, Ni(II)TPPS4, Pd(II)TPPS4, Pt(II)TPPS4 and Zn(II)TPPS4. Complexes of metals that have completely full or completely empty d-orbitals (Cd(II), Mg(II) and Zn(II)) are characterized by high quantum yields of singlet oxygen and are more efficient photosensitizers than the ligand alone. Comparison of the quantum yields of 1 O 2 obtained by the two methods confirmed the assumption that the iodide method yields identical values to the standard method of bleaching of RNO. However, the sensitivity of the iodide method is ten times higher.

Thermal dehydration and decomposition of oxygen-tellurium(VI) compounds with alkali metals and ammonium

In the framework of a systematic study of compounds with hydrogen bonds, thermoanalitycal methods were employed to study four groups of hydrogen tellurates: a) Li2H4TeO6·3H2O, Na2H4TeO6, K2H4TeO6; b) LiH5TeO6, NaH5TeO6·2H2O, KH5TeO6·2H2O; c) NH4HTeO4; d) K4H4Te2O10·7.3H2O. The individual steps in the thermal degradation were described and the intermediates formed were characterized by analytical, infrared spectrometry, powder X-ray and, for NH4HTeO4, also mass spectrometry methods.

Preparation and Characterization of the Nanocomposites SiO2/H-Bond Hydrogensulphate (Hydrogenselenate)

The nanocomposites representing interesting H-bond compounds (Na3H(SO4)2, RbHSO4, RbHSeO4, and Rb3H(SeO4)2) in the silica matrix were prepared by the sol-gel method. Resulting samples were characterised by X-ray diffraction, IR spectroscopy and electron microscopy. Transition temperatures of the nanocomposites were determined using DSC and compared with the TC of the pure bulk active compounds. The shifts of the TC towards lower temperatures or the disappearing of the certain effects in the case nanocomposites were observed. A possible explanation of these phenomena was proposed using the analogy with the superparamagnetic compounds.

Preparation of KHSO4/SiO2 Nanocomposites and Their Physical Properties

A series of SiO2/KHSO4 nanocomposites with various SiO2/salt ratios was prepared where the active compound was added before gelation. The sol was prepared by mixing of these hydrogen salts, TEOS (tetraethyl orthosilicate) and water. After gelation and heat treatment (heating slowly to 200–220°C under vacuum), the samples were characterized by X-ray diffraction, Differential Scanning Calorimetry (DSC), IR spectroscopy, Scanning Electron Microscopy (SEM), and High Resolution Transition Electron Microscopy (HR TEM). DSC measurements showed phase transition temperature shifts that depended on the SiO2/salt ratio. The properties of the nanocomposite samples were compared with the bulk materials. The shift in the phase transitions to lower temperatures was attributed to the particle size effect.