Structural properties and lattice phonons evolution in phenothiazine/iminostilbene solid solutions

Year: 2024

Authors: Giunchi A., Pandolfi L., Della Valle R.G., Salzillo T., Venuti E., Demitri N., Riegler H., Petschacher C., Liu J., Werzer O.

Autors Affiliation: Univ Bologna, Dipartimento Chim Ind Toso Montanari, Viale Risorgimento 4, I-40136 Bologna, Italy; Elettra Sincrotrone Trieste, SS 14 Km 163-5 AREA Sci Pk, I-34149 Basovizza, Trieste, Italy; Graz Univ, Dept Pharmaceut Technol & Biopharm, Inst Pharmaceut Sci, Univ Pl 1, A-8010 Graz, Austria; Univ Warwick, Dept Phys, Coventry CV4 7AL, England; Joanneum Res Forsch Gesell mbH, Franz Pichler Str 30, A-8160 Weiz, Austria; INECA, Via Magnanelli 6-3, I-40033 Bologna, Italy; CNR, INO, Via Branze 45, I-25123 Brescia, Italy.

Abstract: Together with co-crystals, solid solutions of molecular systems are vital in the design of multicomponent solids that exhibit improved physical and chemical properties compared to those of pure substances. In this work, both the bulk and thin film phases of the molecular solid solutions of the active pharmaceutical ingredients (APIs) phenothiazine (PTZ) and iminostilbene (ISB) are characterized structurally, while low frequency Raman spectroscopy coupled with DFT simulations is employed to understand the impact of the loss of perfect periodicity of the mixed system on its lattice dynamics. X-ray diffraction methods show the statistical distribution of the two molecules in the structure, and the steady variation of the structural parameters with solution composition, confirming that we are dealing with monophasic mixtures. The spectroscopic properties are demonstrated to be different depending on the nature of the vibrational mode. While the vibrational spectra of molecules can always be decomposed into a superposition of the spectra of the two pure compounds, the lattice phonons exhibit a continuous evolution throughout the solution series.

Journal/Review: CRYSTENGCOMM

More Information: The authors want to thank the synchrotron ELETTRA and especially Luisa Barba and Heinz Amenitsch for great support at their respective beamlines, i.e. XRD1 and SAXS. Project funded under the National Recovery and Resilience Plan (NRRP), Mission 04 Component 2 Investment 1.5 – NextGenerationEU, call for tender no. 3277 dated 30/12/2021 (award number: 0001052 dated 23/06/2022). This work has also been supported by the project POLYPHON funded by the MUR Progetti di Rice rca di Rilevante Interesse Nazionale (PRIN) Bando 2022 – grant 2022XZ2ZM8. T. S. thanks the Programma per Giovani Ricercatori Rita Levi Montalcini year 2020 (grant PGR20QN52R) of the Italian Ministry of University and Research (MUR) for the financial support.
KeyWords: Initio Molecular-dynamics; Total-energy Calculations; Crystal; Antioxidants; Tools; Raman
DOI: 10.1039/d4ce00605d