Direct functionalization of C−H bonds by electrophilic anions

Alkanes and [B12X12]2−(X = Cl, Br) are both stable compounds which are difficult to functionalize. Here we demonstrate the formation of a boron−carbon bond between these substances in a two-step process. Fragmentation of [B12X12]2−in the gas phase generates highly reactive [B12X11]−ions which spontaneously react with alkanes. The reaction mechanism was investigated using tandem mass spectrometry and gas-phase vibrational spectroscopy combined with electronic structure calculations. [B12X11]−reacts by an electrophilic substitution of a proton in an alkane resulting in a B−C bond formation. The product is a dianionic [B12X11CnH2n+1]2−species, to which H+is electrostatically bound. High-flux ion soft landing was performed to codeposit [B12X11]−and complex organic molecules (phthalates) in thin layers on surfaces. Molecular structure analysis of the product films revealed that C−H functionalization by [B12X11]−occurred in the presence of other more reactive functional groups. This observation demonstrates the utility of highly reactive fragment ions for selective bond formation processes and may pave the way for the use of gas-phase ion chemistry for the generation of complex molecular structures in the condensed phase.

Detection and Quantification of Carbohydrate-Deficient Transferrin by MALDI-Compatible Protein Chips Prepared by Ambient Ion Soft Landing

BACKGROUND Transferrin is synthetized in the liver and is the most important iron-transport carrier in the human body. Severe alcohol consumption leads to alterations in glycosylation of transferrin. Mass spectrometry can provide fast detection and quantification of transferrin isoforms because they have different molecular masses. In this study, we used antibody chips in combination with MALDI-TOF MS for the detection and quantification of transferrin isoforms. METHODS Protein chips were prepared by functionalization of indium tin oxide glass using ambient ion soft landing of electrosprayed antitransferrin antibody. Two microliters of patient serum was applied on the antibody-modified spots, and after incubation, washing, and matrix deposition, transferrin isoforms were detected by MALDI-TOF MS. Peak intensities of each transferrin form were used to calculate total carbohydrate-deficient transferrin (CDT). The CDT values obtained by the MALDI chip method were compared with the results obtained by a standard capillary electrophoresis (CE). RESULTS The chip-based MALDI-TOF MS method was used for enrichment and detection of CDT from human serum. A sample cohort from 186 patients was analyzed. Of these samples, 44 were positively identified as belonging to alcoholic patients, whereas 142 were negative by the MALDI chip approach. The correlation of the data obtained by the CE and the chip-based MALDI was r = 0.986, 95% CI. CONCLUSIONS Functionalized MALDI chips modified by antitransferrin antibody prepared by ambient ion soft landing were successfully used for detection and quantification of CDT from human sera.

Mass Spectrometry for Synthesis and Analysis

Mass spectrometry is the science and technology of ions. As such, it is concerned with generating ions, measuring their properties, following their reactions, isolating them, and using them to build and transform materials. Instrumentation is an essential element of these activities, and analytical applications are one driving force. Work from the Aston Laboratories at Purdue University's Department of Chemistry is described here, with an emphasis on accelerated reactions of ions in solution and small-scale synthesis; ion/surface collision processes, including surface-induced dissociation (SID) and ion soft landing; and applications to tissue imaging. Our special interest in chirality and the chemistry behind the origins of life is also featured together with the exciting area of tissue diagnostics.