Machine learning models for predicting IR spectra of molecular ions (infrared ion spectroscopy, IRIS) have yet to be reported owing the relatively sparse experimental data sets available. To overcome this limitation, we employ Graphormer-IR model neutral molecules as a knowledgeable starting point and then transfer refine predict gaseous ions. A library 10,336 computed small set 312 IRIS is used fine-tuning. Nonspecific global graph encodings that describe charge state (i.e.,...

Liquid chromatography (LC) is a cornerstone of analytical separations, but comparing the retention times (RTs) across different LC methods challenging because variations in experimental parameters such as column type and solvent gradient. Nevertheless, RTs are powerful metrics tandem mass spectrometry (MS2) that can reduce false positive rates for metabolite annotation, differentiate isobaric species, improve peptide identification. Here, we present Graphormer-RT, novel graph transformer...

Differential mobility spectrometry (DMS) can distinguish ions based upon the differences in their high- and low-field ion mobilities as they experience asymmetric waveform applied to DMS cell. These are known be influenced by ions' structure, m/z, charge distribution (i.e., resonance structures) within themselves, well gas-phase environment of While these associations have been developed over time through empirical observations, exact role structures or interactions with clustering molecules...

In this study, we report on the use of differential mobility spectrometry (DMS) as a tool for studying tautomeric species, allowing more in-depth interrogation these elusive isomers using ion/molecule reactions and tandem mass spectrometry. As an example, revisit case study in which gas-phase hydrogen-deuterium exchange (HDX)-a probe ion structure spectrometry-actually altered analyte by tautomerization. For N- O-protonated tautomers 4-aminobenzoic acid, when separated DMS subjected to...

Experiments have been carried out in which electrospray ionization has used to generate ionic complexes of all-cis 1,2,3,4,5,6 hexafluorocyclohexane. These were subsequently mass isolated a quadrupole ion trap spectrometer and then irradiated by the tunable infrared output free electron laser 800–1600 cm–1 range. From frequency dependence fragmentation complexes, vibrational signatures obtained. Computational work parallel reveals that formed are very strongly bound among most Na+ Cl– ever...

A new parallelized calculation package predicts collision cross sections with high accuracy and efficiency.

During preclinical evaluations of drug candidates, several physicochemical (p-chem) properties are measured and employed as metrics to estimate efficacy in vivo. Two such p-chem the octanol-water partition coefficient, Log P, distribution D, which useful estimating drugs within body. P D traditionally using shake-flask method high-performance liquid chromatography. However, it is challenging measure these for species that very hydrophobic (or hydrophilic) owing low equilibrium concentrations...

Infrared (IR) spectroscopy is an important analytical tool in various chemical and forensic domains a great deal of effort has gone into developing

The geometric structures of small cationic rhodium clusters Rh(n)(+) (n = 6-12) are investigated by comparison experimental far-infrared multiple photon dissociation spectra with calculated using density functional theory. found to favor based on octahedral and tetrahedral motifs for most the sizes considered, in contrast previous theoretical predictions that should cubic motifs. Our findings highlight need further development computational methods treat these high-spin transition metal clusters.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTInfrared Induced Reactivity on the Surface of Isolated Size-Selected Clusters: Dissociation N2O Rhodium ClustersSuzanne M. Hamilton†, W. Scott Hopkins†, Dan J. Harding‡§, Tiffany R. Walsh‡, Philipp Gruene§, Marko Haertelt§, André Fielicke§, Gerard Meijer§, and Stuart Mackenzie*†View Author Information Department Chemistry, University Oxford, Physical Theoretical Chemistry Laboratory, South Parks Road, OX1 3QZ U.K., Centre for Scientific...

Understanding the mechanisms and energetics of ion solvation is critical in many scientific areas. Here, we present a methodlogy for studying using differential mobility spectrometry (DMS) coupled to mass spectrometry. While DMS cell, ions experience electric fields established by high frequency asymmetric waveform presence desired pressure water vapor. By observing how specific ion's behavior changes between high- low-field parts waveform, gain knowledge about aqueous microsolvation that...

Aqueous solubility, log S, and the water-octanol partition coefficient, P, are physicochemical properties that used to screen viability of drug candidates estimate mass transport in environment. In this work, differential mobility spectrometry (DMS) experiments performed microsolvating environments train machine learning (ML) frameworks predict S P various molecule classes. lieu a consistent source experimentally measured values, OPERA package was evaluate aqueous solubility hydrophobicity...

The geometric structure of the Rh$_8^+$ cation is investigated using a combination far-infrared multiple photon dissociation spectroscopy and density functional theory (DFT) calculations. energetic ordering different structural motifs found to depend sensitively on choice pure or hybrid exchange functionals. Comparison experimental calculated spectra suggests cluster have close-packed, bicapped octahedral structure, in contrast recent predictions cubic for neutral cluster. Our findings...

Far- and mid-infrared multiple photon dissociation spectroscopy has been employed to study both the structure surface reactivity of isolated cationic rhodium clusters with surface-adsorbed nitrous oxide, Rh(n)N(2)O(+) (n = 4-8). Comparison experimental spectra recorded using argon atom tagging method those calculated density functional theory (DFT) reveals that oxide is molecularly bound on cluster via terminal N-atom. Binding thought occur exclusively atop sites adopting close-packed...

The microsolvated state of a molecule, represented by its interactions with only small number solvent molecules, can play key role in determining the observable bulk properties molecule. This is especially true cases where strong local hydrogen bonding exists between molecule and solvent. One method that probe states charged molecules differential mobility spectrometry (DMS), which rapidly interrogates an ion's transitions solvated desolvated gas phase (i.e., few present). However, results...

The low-energy region of the potential energy surface (PES) protonated phenylalanine/serine dimer is mapped using basin-hoping search algorithm, and 37 isomers are identified within 180 kJ·mol–1 global-minimum structure. Cluster structures grouped hierarchical clustering to partition PES in terms nuclear configuration. Calculated IR spectra for various then compared with isomer-specific by means cosine distance metric facilitate spectral assignment identify which regions populated...

Abstract An in vivo direct-immersion SPME sampling coupled to comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry (GCxGC-ToFMS) was employed capture real-time changes the metabolome of ‘Honeycrisp’ apples during ripening on tree. This novel approach successful acquiring a broad metabolic fingerprint, capturing unique metabolites and detecting profiles associated with fruit maturation. Several chemical classes, including volatile esters, phenylpropanoid...

Supervised machine learning is used to create a predictive model of differential ion mobility.

The complexation of perfluorinated dodecaborate, B12F122-, with protonated diaminoalkanes, [H2N(CH2)nH2N] (n= 2 - 12), is studied a combination infrared multiple photon dissociation (IRMPD) action spectroscopy and ion mobility spectrometry. Singly charged clusters the form [B12F12 + H2N(CH2)nH2N H]- (n = 2-12) doubly [2B12F12 2H]2- are observed characterized experimentally computationally. For singly clusters, low-energy structural motifs associated monodentate bidentate binding...

Differential mobility spectrometry (DMS), a tool for separating chemically similar species (including isomers), is readily coupled to mass improve selectivity in analytical workflows. DMS dispersion curves, which describe the dynamic experienced by an ion gaseous environment, show maximum transmission analyte through instrument as function of separation voltage (SV) and compensation (CV) conditions. To date, there exists no fast, general prediction behavior ions. Here, we demonstrate machine...

The site of protonation for gas-phase aniline has been debated many years, with research groups contributing experimental and computational evidence either the amino-protonated or para-carbon-protonated tautomer as global minimum structure. Here, we employ differential mobility spectrometry (DMS) mass (MS) to separate characterize (N-protonated) (p-protonated) tautomers aniline. We demonstrate that upon electrospray ionization (ESI), is protonated predominantly at amino position. Similar...

Clusters of all-cis 1,2,3,4,5,6-hexafluorocyclohexane and the dodecafluorododecaboron dianion, [C6F6H6]n[B12F12]2– (n = 0–4), are investigated in a combined experimental computational study. DFT calculations IRMPD spectra region 800–2000 cm–1 indicate that C6H6F6 binds to open trigonal faces B12F122– via three-point interlocking binding motif. Calculated interactions reveal substantial contributions from C–H···F hydrogen bonding energies among strongest observed for neutral-anion system.

The fast and accurate determination of molecular properties is highly desirable for many facets chemical research, particularly in drug discovery where pre-clinical assays play an important role paring down large sets candidates. Here, we present the use supervised machine learning to treat differential mobility spectrometry - mass data ten topological classes We demonstrate that gas-phase clustering behavior probed our experiments can be used predict candidates' condensed phase properties,...