High-pressure structure and reactivity of crystalline bibenzyl: Insights and prospects for the synthesis of functional double-core carbon nanothreads

Year: 2023

Authors: Agati M., Romi S., Fanetti S., Bini R.

Autors Affiliation: European Lab Nonlinear Spect, LENS, Via N Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy; CCOM CNR, Ist Chim Composti OrganoMetall, Via Madonna Piano 10, I-50019 Sesto Fiorentino, Firenze, Italy; Univ Firenze, Dipartimento Chim Ugo Schiff, Via Lastruccia 3, I-50019 Sesto Fiorentino, Italy; INO CNR, Ist Nazl Ott, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy.

Abstract: The high-pressure synthesis of double-core nanothreads derived from pseudo-stilbene crystals represents a captivating approach to isolate within the thread chromophores or functional groups without altering its mechanical properties. These entities can be effectively utilized to finely tune optical properties or as preferential sites for functionalization. Bibenzyl, being isostructural with other members of this class, represents the ideal system for building co-crystals from which we can synthesize double-core nanothreads wherein bridging chromophores, such as the azo or ethylene moieties, are embedded in the desired concentration within a fully saturated environment. To achieve this, a critical step is the preliminary characterization of the high-pressure behavior of crystalline bibenzyl. We report here an accurate investigation performed through state-of-the-art spectroscopic techniques, Raman and Fourier transform infrared spectroscopy, and x-ray diffraction up to 40 GPa. Our findings reveal a strongly anisotropic compression of the crystal, which determines, at pressures between 1 and 2 GPa, consistent modifications of the vibrational spectrum, possibly related to a torsional distortion of the molecules. A phase transition is detected between 9 and 10 GPa, leading to a high pressure phase where, above 24 GPa, the nanothread formation is observed. However, the observed reaction was limited in extent and required significantly higher pressures in comparison to other members of the pseudo-stilbene family. This comprehensive study is imperative in laying the foundation for future endeavors, aiming to synthesize double-core nanothreads from pseudo-stilbene crystals, and provides crucial insights into the high-pressure behavior and phase transitions of crystalline bibenzyl.

Journal/Review: JOURNAL OF CHEMICAL PHYSICS

Volume: 159 (24)      Pages from: 244507-1  to: 244507-10

More Information: We acknowledge the European Laboratory for Nonlinear Spectroscopy (LENS) for hosting the research, the Deep Carbon Observatory, and the Fondazione CR Firenze for strong support. The research was supported by the following grants: Extreme Physics and Chemistry of Carbon: Forms, Transformations, and Movements in Planetary Interiors funded by the Alfred P. Sloan Foundation; Fondazione Ca ssa di Risparmio di Firenze under the project Utilizzo dell’anisotropia strutturale nella sintesi di nanofili di carbonio diamond-like ad alta pressione.
KeyWords: Azobenzene Trans-stilbene; Universal Equation; Phase-change; Benzene; Polymerization; Temperature; Disorder; Kinetics; State
DOI: 10.1063/5.0174157

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