Anion complexation by glycocluster thioureamethyl cavitands: novel ESI-MS-based methods for the determination of Ka values.

A series of saccharide-thiourea functionalized cavitands was prepared in good yields (72-86 %) by reaction of a tetrakis(aminomethyl) cavitand with the thiocyanate derivatives of acetylated glucose, galactose, and cellobiose. The anion complexation behavior of the acetylated and deacetylated glycocluster thioureamethyl cavitands was studied with electrospray ionization mass spectrometry (ESI-MS) in acetonitrile and in a 1:1 acetonitrile/water mixture, respectively. All compounds show a preference for Cl(-). A linear relationship was found between the square root of the intensity and the concentration of the formed host-guest complex. Based on this relationship, novel methods have been developed to determine K(a) values, by means of direct titration and competition experiments.

Integrated microfluidic system enabling (bio)chemical reactions with on-line MALDI-TOF mass spectrometry.

A continuous flow micro total analysis system (micro-TAS) consisting of an on-chip microfluidic device connected to a matrix assisted laser desorption ionization [MALDI] time-of-flight [TOF] mass spectrometer (MS) as an analytical screening system is presented. Reaction microchannels and inlet/outlet reservoirs were fabricated by powderblasting on glass wafers that were then bonded to silicon substrates. The novel lab-on-a-chip was realized by integrating the microdevice with a MALDI-TOFMS standard sample plate used as carrier to get the microfluidic device in the MALDI instrument. A novel pressure-driven pumping mechanism using the vacuum of the instrument as a driving force induces flow in the reaction microchannel in a self-activating way. Organic syntheses as well as biochemical reactions are carried out entirely inside the MALDI-MS ionization vacuum chamber and analyzed on-line by MALDI-TOFMS in real time. The effectiveness of the micro-TAS system has been successfully demonstrated with several examples of (bio)chemical reactions.

Zipping up 'the crushed fullerene' C60H30:C60 by fifteen-fold, consecutive intramolecular H2 losses.

MALDI TOF-MS of tribenzo[l:1':1"]benzo[1,2-e:3,4-e':5,6-e"]triacephenanthrylene (1a, C60H30) gives C60.+ by multiple intramolecular cyclodehydrogenation reactions.

Characterization of Hydrogen-Bonded Supramolecular Assemblies by MALDI-TOF Mass Spectrometry after Ag+ Labeling.

The high affinity of Ag+ ions for aromatic π donors and cyano groups is exploited in a novel MALDI-TOF mass spectrometric method for the identification of hydrogen-bonded assemblies. The interaction with the Ag+ ions-which, for example, can be complexed by two phenyl groups in a sandwich-type manner (see drawing on the right)-provides positively charged assemblies in a nondestructive way.