Proton transfer on the edge of the salt/cocrystal continuum: X-ray photoelectron spectroscopy of three isonicotinamide salts

DOI: 10.1021/acs.cgd.1c00807

Authors: Paul T. Edwards (University of Leeds) , Lucy K. Saunders (Diamond Light Source) , Anuradha R. Pallipurath (University of Leeds; Future Continuous Manufacturing and Advanced Crystallisation Hub, Research Complex at Harwell (RCaH)) , Andrew J. Britton (University of Leeds) , Elizabeth A. Willneff (University of Leeds) , Elizabeth J. Shotton (Diamond Light Source) , Sven L. M. Schroeder (University of Leeds; Diamond Light Source; Future Continuous Manufacturing and Advanced Crystallisation Hub, Research Complex at Harwell (RCaH))
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystal Growth & Design

State: Published (Approved)
Published: September 2021

Abstract: X-ray photoelectron spectroscopy (XPS) has emerged as a technique that allows for characterization and classification of hydrogen bonding and proton transfer interactions in organic crystal structures, in a way that is complementary to crystallography by X-ray or neutron diffraction. Here, we analyze the nitrogen 1s core-level binding energies (BEs) of isonicotinamide (IN) systems with proton transfer between donor and acceptor groups at short distances. We show how a careful calibration of the BE scale places these salt systems correctly on the edge of the so-called salt–cocrystal continuum. We show how performing a fitting analysis of the data that is consistent with elemental analysis, expected stoichiometry, and quantification of adventitious carbon contamination facilitates the determination of absolute BEs with accuracy and reproducibility within ±0.1 eV. The determined N 1s core-level BEs of the protonated IN acceptors suggest that the local geometric arrangements of the donor, acceptor, and proton can influence the N 1s core-level BE significantly.

Journal Keywords: Salts; Reaction mechanisms; Carbon; Noncovalent interactions; X-ray photoelectron spectroscopy

Subject Areas: Chemistry, Technique Development

Facility: Versatile X-ray Spectroscopy Facility (VXSF)

Added On: 04/10/2021 08:26

Discipline Tags:

Technique Development - Chemistry Chemistry

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