Formation of macrocyclic oligoferrocenes: a matrix-assisted laser desorption/ionization mass spectrometric study

Oligomeric ferrocenes were investigated simultaneously by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOFMS). The oligomers were obtained by the reaction of tetrahydro-4,4,8,8-tetramethyl-4,8-disila-s-indacene-3a,7a-diyldilithium (Li(2)L) with FeCl(2).1.5 THF (THF = tetrahydrofuran). Depending on the reaction conditions up to ten linear-chain and eleven cyclic ferrocene oligomers with masses between 1139 and 5071 Da could be detected unambiguously. The most abundant macrocycles contained ten and seven iron atoms when the reactions were carried out at -20 and 25 degrees C, respectively. The chains had cyclopentadienes as end groups and formally resulted from replacing one iron of a cycle by two hydrogens, which corresponds to a mass difference of 54 Da. Copyright 1999 John Wiley & Sons, Ltd.     

Synthesis and characterization of 5,10,15,20-tetra[3-(3-trifluoromethyl)phenoxy] porphyrin

The newly synthesized 5,10,15,20-tetra[3-(3-trifluoromethyl)phenoxy]porphyrin, TTFMPP, has been characterized using mass spectroscopy, 1H-, 13C- and 19F-NMR, MALDI-TOF mass spectrometry, UV-Vis and fluorescence spectrophotometry, and cyclic voltammetry. The NMR confirmed the structure of the compound and the mass spectrum was in agreement with the proposed molecular formula. The UV-Vis absorption spectrum of TTFMPP shows characteristic spectral patterns similar to those of tetraphenyl porphryin, with a Soret band at 419 nm and four Q bands at 515, 550, 590, and 648 nm. Protonation of the porphyrin with TFA resulted in the expected red shift of the Soret band. Excitation at 419 nm gave an emission at 650 nm. The quantum yield of the porphyrin was determined to be 0.08. Cyclic voltammetry was used to determine the oxidation and reduction potentials of the new porphyrin. Two quasi-reversible one-electron reductions at -1.00 and -1.32 V and a quasi-reversible oxidation at 1.20 V versus the silver/silver chloride reference electrode with tetrabutylammonium tetrafluoroborate as the supporting electrolyte in methylene chloride were observed.