0000000000064417
AUTHOR
Pirjo Vainiotalo
An electrospray ionization Fourier transform ion cyclotron resonance mass spectrometric study of the gas-phase stabilities and fragmentation ofN-alkylammonium resorcarenes
Five N-alkylated ammonium resorcarene derivatives, differing either in the nitrogen atom or in the lower rim alkyl chain, were studied using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The main purpose was to clarify the fragmentation and the relative stabilities of the protonated molecules by collision-induced dissociation (CID) experiments. The results indicate that fragmentation of the upper rim alkyl amino substituents at the 2-position occurs readily. Variation in the gas-phase stabilities of these molecules was also observed. In addition, the proposed fragmentation pathways are depicted.
Alkali metal mediated resorcarene capsules: An ESI-FTICRMS study on gas-phase structure and cation binding of tetraethyl resorcarene and its per-methylated derivative
AbstractElectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) with additional ab initio calculations were used to examine the alkali metal cation binding selectivity (i.e., molecular recognition) and host properties of tetraethyl resorcarene (1) and its per-methylated derivative (2). The significance of intramolecular hydrogen bonding for the crown conformation was demonstrated. The presence of intramolecular flip-flop hydrogen bonding in 1 was confirmed both with calculations and in ND3-exchange experiments. All the alkali metal cations formed host–guest complexes by docking inside the cavity of the host. Complexation with the larger cations, esp…
Noncovalent Saccharide Recognition by Means of a Tetrakis(bile acid)-Porphyrin Conjugate: Selectivity, Cooperation, and Stability
Molecular recognition of Glu, Glc 2 -Glc 6 and Mal 3 by a tetrakis(bile acid)―porphyrin conjugate has been studied by using ESI-FTICR mass spectrometry. The bile acid conjugate was observed to form 1:1 noncovalent complexes with saccharides. The conjugate was found to have size-selectivity towards saccharides with three or more glucose residues. The Glc 3 and Glc 4 also formed kinetically the most stable complexes. The electron capture dissociation (ECD) experiments revealed that in complexation of an oligosaccharide three glucose residues interact with the bile acid conjugate, whereas additional glucose residues are susceptible to fragmentation. The ECD results also showed the significance…
Size- and Structure-Selective Noncovalent Recognition of Saccharides by Tetraethyl and Tetraphenyl Resorcinarenes in the Gas Phase
The noncovalent complexation of tetraethyl and tetraphenyl resorcinarenes with mono-, di-, and oligosaccharides was studied with negative-polarization electrospray ionization quadrupole ion trap and electrospray ionization Fourier-transform ion cyclotron resonance mass-spectrometric analysis. The saccharides formed 1:1 complexes with deprotonated resorcinarenes, which exhibited clear size and structure selectivity in their complexation. In the case of the monosaccharides, hexoses formed much more abundant and kinetically stable complexes than pentoses or deoxyhexoses. A comparison of the mono-, di-, and oligosaccharides revealed that both the relative abundance and stability of the complexe…
Mass spectrometric studies on small open-chain piperazine-containing ligands and their transition metal complexes
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to characterize the complexes formed between open-chain piperazine-containing ligands and transition metal salts (Cobalt, Copper, Zinc, and Cadmium as chlorides, nitrates, and acetates). Only single-charged complexes were observed, formed of one ligand (L) and mainly one metal ion (M). Since the net charge of the complexes was one, a counterion (X) was attached to some of the complexes, with formation of [L + M + X]+ complexes, and a proton was lost from others, as in [L − H + M]+ complexes. In most cases the composition of the complexes was more dependent on the ligand than the metal salt. Collisio…
Ammonium ion mediated resorcarene capsules: ESI-FTICRMS study on gas-phase structure and ammonium ion affinity of tetraethyl resorcarene and its per-methylated derivative
AbstractThe ammonium ion binding affinities of tetraethyl resorcarene (1) and its per-methylated derivative (2) were studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Ten different ammonium ions were tested as guests for the resorcarenes. A strong tendency for complex formation was observed with all ammonium ions of size and charge distribution suitable for noncovalent interactions with the cavities of the resorcarene hosts 1 and 2. Although differences in ammonium ion affinities were observed between 1 and 2 due to the dissimilar conformations, the overall tendency was that increase in the degree of substitution and the length of ca…
Mass spectrometric studies of benzoxazine resorcarenes
Eleven differently substituted 3,4-dihydro-2H-1,3-benzoxazine resorcarenes were studied by electrospray ionisation (ESI) and matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry, using Fourier transform ion cyclotron resonance (FT-ICR) and time-of-flight (TOF) mass spectrometers, respectively. Under ESI conditions it was possible to transfer the intact resorcarenes from solution to the gas phase, yielding [M + H]+ and [M + 2H]+ ions as the main ions observed. Energy increase of the ions induced ready decomposition through successive eliminations of four CH2NR groups. Ion-molecule reactions showed that the ionising proton was situated somewhere inside the molecule and could …
Thermoanalytical studies on sodium 1,2-naphthoqoinone oximesolfonates
Abstract Five sodium 1,2-nitrosonaphtholsulfonatea were prepared or purified and their thermal behaviour studied by TG, DTG and DSC. Pyrolysis MS technique was used to identify evolved gases and FTIR to characterize residuals. The water contents depended on preparation and conservation. The decomposition was analysed in three stages which can be formed by one or more steps. The final product was sodium sulfate in air at 530 °C and the mixture of carbon and sodium sulfide at 950 °C in nitrogen. The structure effects on decomposition is discussed.
ESI-FTICR investigation of triethylammonium ion-driven resorcin[4]arene dimer formation and structure
In the course of mass spectrometric measurements a self-assembled hydrogen bonded resorcinarene dimer was observed, the formation of which was driven by the binding of triethylammonium ion as a guest and as an ionic label.
Mass spectrometric studies on pyridine-piperazine-containing ligands and their complexes with transition metals formed in solution.
Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) methods were used to study open-chain piperazine-containing ligands (L) and their complexes formed with transition-metal salts. ESI and MALDI measurements were performed with a Fourier transform ion cyclotron resonance (FT-ICR) and a time-of-flight (TOF) mass spectrometer, respectively. Only singly charged complexes, between one ligand and one or several metal ions, were formed in the ESI measurements. Because the net charge was always one, one or several counterions were attached to the complex. Under ESI conditions, the complexes formed between the ligands and metal (Co, Ni, Cu, and Cd) salts were [L + M…
Macrocycles prepared from lithocholic acid, piperazine and isomeric pyridine dicarboxylic acids and their selective affinities towards sodium and potassium
Abstract Two novel macrocycles prepared from lithocholic acid, piperazine and pyridine dicarboxylic acids (2,6- and 3,5-isomers), have been characterized by 13C NMR and ESI–MS techniques. In case of the pyridine-2,6-dicarboxylate derivative, the molecular formula of the cycle was C59H87O6N3 (I), while the pyridine-3,5-dicarboxylate derivative (II) was a trimeric structure by molecular mass when compared with I. Furthermore, cycle I showed a special affinity towards potassium cation, while II possessed significant proton and sodium cation recognition properties.
The complex formation of tetracyclohexylammonium C1-resorcinarene with various guests - an electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry study.
The complex formation of a tetraammonium C1-resorcinarene (R+4HCl) was studied using electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Although R+4HCl easily loses its counter ions in the ESI process, a neutral self-assembled structure with an intramolecular circular hydrogen-bonded 16-membered -N(+)-H ... X(-) ... H-N(+)- array with ammonium ion as the charge-giving species was observed in the gas phase. In addition to chloride, several other counter ions were also studied. The size and basicity of the counter ion as well as the size of the charge-giving cation strongly affected the gas-phase stability of the self-assembled system. H/D exchang…
Mass Spectrometric Investigation of Noncovalent Complexation between a Tetratosylated Resorcarene and Alkyl Ammonium Ions
Noncovalent complexation between tetratosylated tetraethyl resorcarene (1) and primary, secondary, and tertiary alkyl ammonium ions (mMe, dMe, tMe, mEt, dEt, tEt, dBu, and dHex) was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Interactions of the noncovalent complexes were investigated by means of competition experiments, collision-induced dissociation (CID) experiments, ion-molecule reactions with tripropylamine and gas phase H/D-exchange reactions with deuteroammonia. Gas phase ion-molecule reactions gave especially valuable information about the structure and properties of the complexes. Resorcarene 1 formed relatively stable…