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Electronic circular dichroism imaging (ECDi) casts a new light on the origin of solid-state chiroptical properties

DOI: 10.1002/chem.202103632 DOI Help

Authors: Marcin Gorecki (Institute of Organic Chemistry, Polish Academy of Sciences) , Filippo Lipparini (Università di Pisa) , Gianluigi Albano (Università di Pisa) , Tamas Javorfi (Diamond Light Source) , Rohanah Hussain (Diamond Light Source) , Giuliano Siligardi (Diamond Light Source) , Gennaro Pescitelli (Università di Pisa) , Lorenzo Di Bari (Università di Pisa)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry – A European Journal , VOL 9

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 17621 , 19225

Abstract: Solid-state ECD (ss-ECD) spectra of a model microcrystalline solid, finasteride, dispersed into a KCl pellet were recorded by using the synchrotron radiation source at the Diamond B23 beamline. Scanning a surface of 36 mm2 with a step of 0.5 mm, we measured a set of ECD imaging (ECDi) spectra very different from each other and from the ss-ECD recorded with a bench-top instrument (1 cm2 area). This is due to the anisotropic part of the ECD (ACD), which averages to zero in solution or on a large number of randomly oriented crystallites, but can otherwise be extremely large. Two-way singular value decomposition (SVD) analysis, through experimental and simulated TDDFT spectra, disclosed that the measured and theoretical principal components are in line with each other. This finding demonstrates that the observed isotropic ss-ECD spectrum is governed by the anisotropy of locally oriented crystals. It also introduces a new quality for ss-ECD measurements and opens a new future for probing and mapping chiral materials in the solid state such as active pharmaceutical ingredients (APIs).

Journal Keywords: active pharmaceutical ingredients; anisotropic circular dichroism; circular dichroism imaging; finasteride; solid-state circular dichroism

Subject Areas: Chemistry, Technique Development

Instruments: B23-Circular Dichroism

Added On: 28/12/2021 10:19

Discipline Tags:

Technique Development - Chemistry Chemistry

Technical Tags: