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Mass spectrometric investigation of gallium and zirconium complexes with octaethylporphyrin and tetraphenylporphyrin
Author(s) -
WitowskaJarosz Janina,
Górski Łukasz,
Malinowska Elźbieta,
Jarosz Maciej
Publication year - 2002
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.387
Subject(s) - chemistry , zirconium , monomer , mass spectrum , tetraphenylporphyrin , crystallography , dimer , gallium , trifluoromethyl , electrospray ionization , mass spectrometry , medicinal chemistry , stereochemistry , inorganic chemistry , photochemistry , porphyrin , organic chemistry , alkyl , chromatography , polymer
Abstract Gallium and zirconium octaethylporphyrin (OEP) and tetraphenylporphyrin (TPP) were examined by electrospray ionization (ESI) mass spectrometry. All systems were prepared in dichloromethane with addition of a stabilizing lipophilic anionic agent, sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (NaTFPB). In the solutions examined both monomeric and dimeric metalloporphyrins were observed. In the gallium‐OEP mass spectrum the ion registered at m / z 601 was attributed to monomeric [Ga(OEP)] + and that at m / z 1219 to the dimeric form, [{Ga(OEP)} 2 OH] + . Peaks appearing in the ESI mass spectra of zirconium systems were substantially less intense, probably owing to the relatively low stability of complexes of this metal caused by its different geometry preferences. The most abundant monomeric zirconium‐OEP complexes were [{Zr(OEP)OH}] + ( m / z 639) and [Zr(OEP)Cl] + ( m / z 657), and dimeric [{Zr(OEP)OH} 2 ] 2+ ( m / z 639). Analogous species were observed in the Zr(TPP) system: monomeric [{Zr(OEP)OH}] + ( m / z 719) and [Zr(TPP)Cl] + ( m / z 737) and dimeric [{Zr(TPP)OH} 2 ] 2+ ( m / z 719). In both cases series of other dimers, e.g. [{Zr(OEP)} 2 O 2 H] + ( m / z 1277), [{Zr(OEP)OH} 2 Cl] + ( m / z 1313), [Zr(TPP) 2 O 2 H] + , ( m / z 1437), [{Zr(TPP)OH} 2 OH] + ( m / z 1455) and [{Zr(TPP)OH} 2 Cl] + ( m / z 1473), appeared. The results obtained confirmed the hypothesis concerning the formation of dimeric metalloporphyrins in solutions containing stabilizing lipophilic anions. It also allowed us to explain the super‐Nernstian slopes of the calibration curves towards primary anions of ion‐selective electrodes with membranes containing the examined metalloporphyrins. Copyright © 2002 John Wiley & Sons, Ltd.