CD Imaging at High Spatial Resolution at Diamond B23 Beamline: Evolution and Applications

Abstract

Circular Dichroism imaging in the 190–650 nm spectral region pionered at Diamond Light Source B23 beamline, has been made possible by the highly collimated microbeam generated at the beamline and has been used to study the homogeneity of the supramolecular structures of thin films of chiral materials deposited on fused quartz substrates. This facility has been expanded with the installation of a Mueller Matrix Polarimeter, MMP, coupled to the beamlight, of which a preliminary data will be discussed. In the solid state, the measurement of CD related to the supramolecular structure is hampered by the presence of circular birefringence, linear dichroism, and linear birefringence that can only be evaluated using the MMP technique. The ability to characterize the chiroptical property of thin chiral films prepared under a variety of conditions and protocols such as drop cast, spin coating, spray at different temperatures and concentrations will enable the determination of the critical parameters for reproducible, uniform and homogeneous specimen preparation, which is the sine qua non for any commercial application. This is of particular importance for optoelectronic materials, but it can also be extended to a broad variety of materials with applications from biosensors to biological tissues.

Imaging deposition-dependent supramolecular chiral organisation

“…The highly collimated light at CD beamline B23 at Diamond Light Source, UK, allows spatial resolution down to 50 µm and mapping of films. [22][23][24][25] An X-Y motorized and temperature-controlled stage (Linkam MDS600) allows CD imaging (CDi) measuring spatially resolved spectra in the 190-650 nm wavelength region at the highest spatial resolution of 50 µm also as a function of temperature to study the effects of annealing on the supramolecular structure in situ. Derivatives of 1,4-diketopyrrolo [3,4-c]pyrrole (DPP) are interesting as active layer components of OPVs, [26][27][28] and their self-assembly can give films with excellent properties.…”

Chirality in peptide‐based materials: From chirality effects to potential applications

“…27,28 For these soft materials, the Mueller matrix polarimetry or ellipsometry could be used to probe their chiral parameters. 29,30 Nuclear magnetic resonance (NMR) is also a powerful tool for the identification of chemical structure of chiral polypeptides, especially for probing the narrow conformational space like α-helices and 3 10 -helices, 31,32 or left-handed polyproline type II helices. 33,34 Furthermore, Fourier transform infrared spectrum (FT-IR), 35,36 Raman spectrum, 37,38 and isothermal titration calorimetry (ITC) [39][40][41] have been successfully used to investigate the roles of delicate groups in chiral recognition and assembly behaviors.…”

“…Since the function and activity of peptides are closely related to their foldings, the characterization of chiroptical properties of the films is essential for the uniform reproduction 27,28 . For these soft materials, the Mueller matrix polarimetry or ellipsometry could be used to probe their chiral parameters 29,30 . Nuclear magnetic resonance (NMR) is also a powerful tool for the identification of chemical structure of chiral polypeptides, especially for probing the narrow conformational space like α‐helices and 3 10 ‐helices, 31,32 or left‐handed polyproline type II helices 33,34 .…”

Electronic Circular Dichroism Imaging (ECDi) Casts a New Light on the Origin of Solid‐State Chiroptical Properties

“…Measuring the ECD in the solid state of a large area has two consequences: first, the structural information related to small domains (size of ∼100 μm and below) is entirely lost; second, spectral artifacts due to local anisotropies, in particular linear dichroism (LD), and linear birefringence (LB) can be present and cannot be discriminated. The recent development of ECD imaging (ECD i ) pioneered at the Diamond B23 beamline [8] has enabled the mapping of large sample surfaces at various spectral resolutions down to 0.01 mm 2 because of the highly collimated micro light beam of B23 beamline. Applications of ECD i have revealed the polymorphism of thin films of organic semiconductors and optoelectronic materials enabling the discrimination of different supramolecular architectures, possibly related to multiple aggregation pathways, within the areas investigated [7]…”