Belgian Phthalocyanine Theses

2 entries, January 28, 2004

1993

CODE: 1993BE001
AU-EN: Parton, R.
PY: 1993
TI: Zeolite encaged metallo-phthalocyanines as mimic for cytochrome P-450 enzyme and as catalyst for selective oxygenation reactions
UNI: Leuven Kath. Univ.

2002

CODE: 2002BE001
AU-EN: SLEVEN, Jurgen
TY: Doctoral thesis
PY: 2002
LA: English
TI-EN: Mesomorphism and Optical Properties of Peripherally Substituted Phthalocyanines: Influence of Chain Length, Linking Group and Central Metal Ion
UNI: Katholieke Universiteit Leuven, Belgium
TUT-EN: Prof. Dr. Koen Binnemans
ABST: We synthesised three different peripherally octa-substituted (alkoxy, alkyl and alkoxymethyl) phthalocyanines and their complexes. We were interested in the influence of the central metal ion, the substituent type and the chain length on the thermal behaviour and optical properties. We investigated the metal-free compounds, a selection of transition metal complexes (Zn(II), Cu(II), Ni(II), Co(II), V(IV)O) and the octa-alkoxy substituted lanthanide(III) complexes. A recent technique that uses microwave radiation as the energy source was successfully applied for obtaining the unsubstituted phthalocyanine lanthanide complexes. Optical microscopy, DSC, TGA-DTA and high-temperature X-ray diffraction were used to study the thermal properties of the products. All of the discussed compounds exhibited a relatively wide mesomorphic range and showed enantiotropic behaviour. The absence of polymesomorphism was found for all of our discotic liquid-crystalline peripherally octa-substituted phthalocyanines and metallophthalocyaninato complexes. The mesophase observed was the hexagonal columnar mesophase (ColH) for all but the vanadyl complexes, which exhibited the rectangular columnar (ColR) mesophase. Side-chains with a length of fewer than four carbon atoms did not demonstrate a mesophase. For all investigated homologous series, the melting point generally decreased with increasing chain length. The decrease was more relevant for shorter chain lengths. At longer chain lengths, the relationship was less obvious for some types of compounds (lanthanide complexes). The clearing points decreased more drastically with increasing chain length. This trend was more pronounced for the octa-alkoxy side-chains. The melting points were in general much higher for the octa-alkyl phthalocyanines than for the octa-alkoxy and the octa-alkoxymethyl compounds. For the octa-alkoxy and octa-alkyl compounds, the vanadyl ions showed the strongest stabilising effect on the mesophase compared to the metal-free ligand. They had lower melting temperatures than the ligands. For the other transition metals the melting temperatures increased, but in the whole the mesophase was stabilised due to the strong increase of the clearing point. The strongest increase of the melting point was found for Zn2+. For the alkyl-type substituents the correlation between the central metal ion and the mesophase stability was somewhat less clear. Incorporation of lanthanide ions reduced the mesophase range by both increasing the melting point and a decrease of the clearing point. The optical properties were studied by absorption and MCD-spectroscopy. The phthalocyanine compounds we synthesized all show a strong light absorption. Peripheral substitution has a minor effect on the Q-band position. The choice of the central metal ion nevertheless can influence the optical spectra.
KW: Phthalocyanines; Lanthanides; liquid crystals
URL: N/A

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Dr. Michael Klaus Engel

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