Masayuki Kubota

Synthesis and structure of nitrene-C60 adduct, C60NPhth (Phth=Phthalimido)

Abstract Phthalimidonitrene (:NPhth) generated from H 2 NPhth and lead tetraacetate in chlorobenzene was found to add to C 60 , affording C 60 (NPhth) n (n=1–4). The adducts were separated, and the mono-adduct was spectroscopically characterized as an aziridine structure at a 6/6-ring junction. The electron affinity and aziridine inversion are significantly influenced by the substituents on the aziridine nitrogen.

Negative-ion fast atom bombardment tandem mass spectrometry for characterization of sulfated unsaturated disaccharides from heparin and heparan sulfate.

Negative-ion fast atom bombardment tandem mass spectrometry has been used in the characterization of non-, mono-, di- and trisulfated disaccharides from heparin and heparan sulfate. The positional isomers of the sulfate group of monosulfated disaccharides were distinguished from each other by negative-ion fast atom bombardment tandem mass spectra, which provide an easy way of identifying the positional isomers. This fast atom bombardment collision induced dissociation mass spectrometry/mass spectrometry technique was also applied successfully to the characterization of di- and trisulfated disaccharides.

SYNTHESIS AND CHARACTERIZATION OF C60 DERIVATIVES POSSESSING TEMPO RADICALS

Abstract The sodium salt of TEMPON tosylhydrazone was pyrolyzed in chlorobenzene in the presence of C60 to give the adducts C60(TEMPO)n (n = 1 – 3) [TEMPO = 2,2,6,6-tetramethyl-piperidindash1-oxyl, TEMPO = 4-oxo-TEMPO]. The adducts were isolated by means of gel permeation chromatography, and characterized by mass, IR, UV/Vis, and ESR spectroscopies. The structure of C60(TEMPO) was determined to be an open [5,6] adduct. The magnetic measurements ensured the radical purity.

FAB CID-MS/MS characterization of tetrasaccharide tri- and tetrasulfate derived from the antigenic determinant recognized by the anti-chondroitin sulfate monoclonal antibody MO-225

The fast atom bombardment (FAB) collision induced dissociation (CID)-mass spectrometry/mass spectrometry (MS/MS) technique was successfully applied to characterize and identify the structures of the immunoreactive trisulfated and tetrasulfated tetrasaccharides that were obtained from the chondroitin sulfate in a shark fin using a treatment with chondroitinase ABC.

Unusual reactions of C60 with aldehydes in the presence of aqueous ammonia

Abstract Fullerene C 60 reacts with alkylaldehydes in the presence of aqueous ammonia to give 2,5-dialkyl-substituted pyrrolidine derivatives. The reaction of phenylacetaldehyde under similar conditions afforded C 60 (H)(CH 2 Ph) via possible decarbonylation. On the basis of the product analysis, reaction mechanisms are proposed in which C 60 plays the role of a dipolarophile or radical scavenger.

Characterization of oligosaccharides of the lactosamine series derived from keratan sulfates by tandem mass spectrometry

Positive- and negative-ion fast-atom bombardment tandem mass spectrometry with collision-induced dissociation (FAB-CID-MS/MS) has been used in the characterization of di-and tetra-saccharides of the lactosamine series from keratan sulfates. FAB-CID-MS/MS of Galβ1-4GlcNAc (L1) exhibited strong fragment ions originating from ring cleavage at the reducing-terminal sugar moiety together with glycosidic bond-cleavage ions, whereas GlcNAcβ1-3Gal (K1) showed strong glycosidic bond-cleavage ions but no ring-cleavage ions. A series of ring-cleavage fragment ions was observed with members of the L-series which have free hydroxyl groups at the C1 and C3 positions. CID-MS/MS spectra of the [M + Na – SO3]+ ion (m/z 406) from L2 and the [M + Na − 2SO3]+ ion (m/z 406) from L4 were almost identical with the CID-MS/MS spectrum of the [M + Na]+ ion (m/z 406) from L1, which indicated that the sugar skeletons of L2 and L4 are the same as that of L1. On the other hand, the CID-MS/MS spectrum of the [M + Na – SO3]+ ion (m/z 508) from L4 did not resemble that of the [M + Na]+ ion (m/z 508) from L2. The former showed peaks that were additional to the peaks in the latter. Since these extra peaks were accounted for on the basis of the structure of L3 [Galβ1(6S)-4GlcNAc, S = sulfate], the in-source loss of sulfate groups by ester exchange upon FAB ionization takes place in a dual manner; one reaction at the non-reducing terminal sugar to give L2 and the other at the reducing-terminal sugar to give L3. The CID-MS/MS spectra were characteristic for the tetrasaccharides L1-L1, L2-L2 and L4-L4 while in-source fragmentation confirms the component disaccharides of each tetrasaccharide. The structure of a tetrasaccharide trisulfate was confirmed as L2–L4 and not L4–L2 by CID-MS/MS. Negative-ion FAB-CID-MS/MS spectra of the sulfated di-and tetra-saccharides showed a pattern similar to that of the positive-ion spectra. Subtraction of the CID-MS/MS spectrum of the [M – H]− ion of L2 [Galβ1-4GlcNAc(6S)] from that of the [M – H – SO3]− ion of L4 [Gal(6S)β1-4GlcNAc(6S)] gave several specific ions whose origins were nicely explained on the basis of the structure of L3. The structure of a pentasaccharide consisting of N-acetylneuraminic acid and a tetrasaccharide trisulfate was confirmed, on the basis of FAB-CID-MS/MS, as NeuNAcα2-6L2-L4.

Positive-ion fast atom bombardment tandem mass spectrometry for characterization of sulfated unsaturated disaccharides from heparin and heparan sulfate

Positive-ion fast atom bombardment tandem mass spectrometry has been used in the characterization of non-, mono-, di- and trisulfated disaccharides from heparin and heparan sulfate. The positional isomers of sulfate groups of monosulfated disaccharides have been distinguished from each other by positive-ion fast atom bombardment tandem mass spectra, which provide an easy way of identifying the positional isomers. The fast atom bombardment collision-induced dissociation mass spectrometry/mass spectrometry technique was also applied successfully to the characterization of di- and trisulfated disaccharides.

Synthesis and Mass Spectral Analysis of C60 - Dihalocarbene Adducts

ABSTRACT The monoadducts of C60 with dibromo-, bromochloro-, and diiodocarbenes were synthesized and characterized. The mass spectra (MS) of CgrjCXY (X, Y= CI, CI; Br, Br; and Br, CI) were measured by the FAB, ESI, MALDI, and LD methods. The LDMS revealed that oligomerization reaction occurred to exhibit signals ascribable to C2n (2n = 122 -132 and 184 -196).

Fullerene spin label. Synthesis and characterization of the [60]fullerene-substituted TEMPO radical

A spin-labelled reagent C60(TEMPO)(TEMPO = 2,2,6,6-tetramethylpiperidin-1-oxyl) is synthesized, purified by LC, and characterized by spectroscopic, magnetic and electrochemical measurements.

Synthesis and Spectral Characterization of Difunctional Fullerenes

ABSTRACT The oxidation of C60 with m-chloroperbenzoic acid gave C60O2 with a high positional selectivity, as the 13C NMR analysis suggested. Diadducts C60CCI2O, C60CCl2(anthracene), C60CCl2[(CH2CH2)2N2], and C60CCI2[Pt-(PPh3)2] were synthesized, isolated, and characterized by negative ion FAB mass spectroscopy.