Nicole Joy Rijs

Cryptophanes can selectively encapsulate small molecules and cations. Tuning host-guest selectivity requires insight into molecular recognition, which is analytically accessible with ion mobility mass spectrometry (IM-MS) via the conformational dynamics of complexation. Using activated IM-MS to differentiate between encapsulated and externally associated species, anti -cryptophanes complexes of the cation H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , Mg ²⁺ , and Ag ⁺ were investigated. The m/z of fragments are characteristic of the binding mode of the host and guest pair. Using the combination of characteristic m/z and changes in ion mobility, IM-MS was sensitive to the host’s binding mode and provided further support to whether encapsulation had taken place. These findings demonstrate that activated IM-MS can sensitively probe cryptophane binding modes and provide new insight into the selectivity of cation encapsulation.

Exhaled breath containing volatile organic compounds (VOCs) can be analysed non-invasively and has potential applications in disease diagnosis. Previous high-field asymmetric waveform ion mobility spectrometry (FAIMS)-based breath studies have primarily used low-resolution FAIMS with ion current detection rather than mass spectrometry (MS). Here, atmospheric pressure chemical ionisation (APCI) was coupled with high-resolution FAIMS-MS for direct breath analysis. APCI-FAIMS-MS increased the number of detected breath features by >200% compared with APCI-MS alone and consistently detected 60–130 breath features per sample. Within-participant heatmap consistency was comparable across the four participants based on structural similarity index analysis. Exploratory principal component analysis showed participant-associated clustering of breath profiles. These results demonstrate that high-resolution FAIMS substantially enhances breath feature detection and provides an orthogonal separation dimension for untargeted breath profiling. Future studies involving larger cohorts and disease-specific populations will determine whether the increased breath feature coverage afforded by high-resolution FAIMS can improve VOC-based classification and diagnostic performance.

Neonicotinoids and organophosphates are important analytes due to their use as insecticides and environmental profiles. Cationized imidacloprid and chlorpyrifos as prototypical examples of these were analyzed with drift tube, traveling wave, trapped ion, and cyclic ion mobility mass spectrometry, with experimental collision cross sections (ExpCCSN2) derived for each to help understand their gas phase structures. The ExpCCSN2 of potassiated imidacloprid and potassiated chlorpyrifos are reported for the first time. The cross-platform ExpCCSN2 for [imidacloprid + K]+ is 160–165 Å2 and for [chlorpyrifos + K]+ is 175–176 Å2. Consistent assignment of the [imidacloprid + H]+ structure is achieved based on combining evidence from current work, literature interlaboratory CCS values, DFT energetics, predicted CCS (CalcCCSN2) and literature infrared multiple photon dissociation (IRMPD) spectroscopy. As expected, all cationized species here form charge solvated structures in the gas phase. Imidacloprid coordinates all three cations at the pyridinic N, with a varying degree of nitroguanidine non-covalent interaction for each, depending on the cation. Sodiated and potassiated imidacloprid ions have a 10-membered ring structure where the overall size trend depends more on the non-covalent interaction with nitroguanidine than the incorporated cation size, resulting in different structures. Chlorpyrifos also coordinates cations at the N, but consistently forms 6-membered ring structures. Sodiated and potassiated species change in size relative to the size of the incorporated cation. The consistency of interlaboratory results and current results also support confident assignment for the protomer of [chlorpyrifos + H]+.

Neonicotinoids and organophosphates are important analytes due to their use as insecticides and environmental profiles. Cationized imidacloprid and chlorpyrifos as prototypical examples of these were analyzed with drift tube, traveling wave, trapped ion, and cyclic ion mobility mass spectrometry, with experimental collision cross sections ( ^Exp CCS _N2 ) derived for each to help understand their gas phase structures. The ^Exp CCS _N2 of potassiated imidacloprid and chlorpyrifos are reported for the first time. The cross-platform ^Exp CCS _N2 for [imidacloprid+K] ⁺ is 160−165 Ų and for [chlorpyrifos+K] ⁺ is 175–176 Ų. Consistent assignment of [imidacloprid+H] ⁺ structure is achieved based on current work, literature interlaboratory CCS values, DFT energetics, predicted CCS ( ^Calc CCS _N2 ) and literature IRMPD spectroscopy. Imidacloprid coordinates cations at the pyridinic N, with a varying degree of nitroguanidine interaction that depends on the cation. Sodiated and potassiated imidacloprid ions have a 10-membered ring structure where the overall size depends more on the non-covalent interactions than the incorporated cation size. Chlorpyrifos also coordinates cations at the N, but consistently forms 6-membered ring structures. Overall size trends for sodiated and potassiated species follow the cation size trends, revealing the change in size due to incorporated cation. The consistency of interlaboratory results and current results also support confident assignment for the protomer of [chlorpyrifos+H] ⁺ .

Neonicotinoids and organophosphates are important analytes due to their use as insecticides and environmental profiles. Cationized imidacloprid and chlorpyrifos as prototypical examples of these were analyzed with drift tube, traveling wave, trapped ion, and cyclic ion mobility mass spectrometry, with experimental collision cross sections ( ^Exp CCS _N2 ) derived for each to help understand their gas phase structures. The ^Exp CCS _N2 of potassiated imidacloprid and chlorpyrifos are reported for the first time. The cross-platform ^Exp CCS _N2 for [imidacloprid+K] ⁺ is 160−165 Ų and for [chlorpyrifos+K] ⁺ is 175–176 Ų. Consistent assignment of [imidacloprid+H] ⁺ structure is achieved based on current work, literature interlaboratory CCS values, DFT energetics, predicted CCS ( ^Calc CCS _N2 ) and literature IRMPD spectroscopy. Imidacloprid coordinates cations at the pyridinic N, with a varying degree of nitroguanidine interaction that depends on the cation. Sodiated and potassiated imidacloprid ions have a 10-membered ring structure where the overall size depends more on the non-covalent interactions than the incorporated cation size. Chlorpyrifos also coordinates cations at the N, but consistently forms 6-membered ring structures. Overall size trends for sodiated and potassiated species follow the cation size trends, revealing the change in size due to incorporated cation. The consistency of interlaboratory results and current results also support confident assignment for the protomer of [chlorpyrifos+H] ⁺ .

An efficient, customisable approach for the assembly of stable covalent macrocycles and cages has been developed using the reaction of fused polynorbornane based bis-diols and commercially available boronic acids.

Ionization-driven conformational changes in N -arylsulfonamidocalix[4]arenes enable a narrow-range, pH-controlled “binding switch” for cationic dyes near neutral pH.

Herein the morphology of aminomethylphosphonic acid (AMPA)-metal aggregates are analysed by ion mobility-mass spectrometry, DFT and IRMPD spectroscopy. Matching experimental collision cross section to the DFT predicted minima allowed unambiguous assignment of [M(AMPA)(AMPA-H)]⁺ where M = Mg²⁺, Ca²⁺, and Mn²⁺. Two distinct structural families of [M(AMPA)(AMPA-H)]⁺ M = Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Cu²⁺, and Zn²⁺. were differentiated by ion mobility – mass spectrometry. Groupings of experimental collision cross sections were observed for a square pyramidal geometry, (M = Ca²⁺, Sr²⁺, Ba²⁺) versus a seesaw geometry (M = Mg²⁺, Mn²⁺, Cu²⁺, and Zn²⁺), paving the way for distinction of aggregates at the earliest stages of assembly.

The gas-phase cross-platform collision cross sections (CCS) of cationized (protonated, sodiated, and potassiated) imidacloprid and chlorpyrifos were analyzed with single- and multi-field drift tube, traveling wave, trapped ion, and cyclic ion mobility mass spectrometry. The experimental cross-platform CCS are in the range of: [imidacloprid+H]+ = 154−158 Å; [imidacloprid+Na]+ = 158–160 Ų; [imidacloprid+K]+ = 160−165 Ų; [chlorpyrifos+H]+ = 163−166 Ų; [chlorpyrifos+Na]+ = 170−173 Ų, and [chlorpyrifos+K]+ = 175–176 Ų, and are within ~3% of each other and inter-laboratory values. DFT predicts imidacloprid coordinates cations at the pyridinic N, with a degree of nitroguanidine interaction that depends on the cation, while chlorpyrifos also coordinates cations at the N, but consistently forms 6-membered ring structures. The theoretically predicted CCS of protonated imidacloprid deviated significantly (7−10%) from the experimental CCS. In contrast, sodiated and potassiated imidacloprid ions’ theoretically predicted CCS were consistent (2−3%) with the experimental CCS, supporting a more compact 9-membered ring-shaped structure compared to the protonated congener. On the other hand, predicted CCS for protonated chlorpyrifos matched the experimental CCS well (2−5%), but sodiated and potassiated chlorpyrifos had less agreement between calculated and experimental CCS (>5.5%), however structural trends are reproduced. While cross-platform variations are minimal, discrepancies in predicted CCS highlight the need for standardized protocols before CCS can reliably identify pesticide residues.

An efficient, customisable approach for the assembly of covalent macrocycles and cages has been developed using the reaction of fused polynorbornane based bis-norbornane diols and commercially available boronic acids. The resultant assemblies were resistant to hydrolysis even after 24-hour exposure to solutions of either acetic acid or trifluoroacetic acid. The ability to customise the requisite bis-diol to various lengths and dihedral angle (here both 90° and 180°) and then combine with di or triboronic acids allows access to range of architectures.