Transient two-dimensional vibrational spectroscopy of an operating molecular machine

• Main Authors: Panman, Matthijs R., van Dijk, Chris N., Huerta-Viga, Adriana, Sanders, Hans J., Bakker, Bert H., Leigh, David A., Brouwer, Albert M., Buma, Wybren Jan, Woutersen, Sander
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2018
• Subjects: Molecular Analysis; Spectroscopy
• Online Access: https://hdl.handle.net/10356/87401; http://hdl.handle.net/10220/44407
• Institution: Nanyang Technological University

Synthetic molecular machines are promising building blocks for future nanoscopic devices. However, the details of their mechanical behaviour are in many cases still largely unknown. A deeper understanding of mechanics at the molecular level is essential for the design and construction of complex nanodevices. Here, we show that transient two-dimensional infrared (T2DIR) spectroscopy makes it possible to monitor the conformational changes of a translational molecular machine during its operation. Translation of a macrocyclic ring from one station to another on a molecular thread is initiated by a UV pulse. The arrival of the shuttling macrocycle at the final station is visible from a newly appearing cross peak between these two moieties. To eliminate spectral congestion in the T2DIR spectra, we use a subtraction method applicable to many other complex molecular systems. The T2DIR spectra indicate that the macrocycle adopts a boat-like conformation at the final station, which contrasts with the chair-like conformation at the initial station.