Regulating photoreactivity in a polymorphic bi-component solid through large synthons

Area of Science:

• Materials Science
• Crystallography
• Photochemistry

Background:

• Polymorphism in bi-component crystals is crucial for tailoring material properties.
• Controlling crystal structure enables precise engineering of molecular solids.

Purpose of the Study:

• To derive and characterize two distinct polymorphs of a functional bi-component molecular solid.
• To investigate the photochemical and photomechanical behaviors of these polymorphs.

Main Methods:

• Utilized Long-range Synthon Aufbau Modules (LSAM) for crystal engineering.
• Tuned substituent nature and position to control polymorphism.
• Analyzed photochemical reactions (cis-trans isomerization, [2+2] photodimerization) and photomechanical responses.

Main Results:

• Successfully derived two polymorphs (Form I and Form II) with distinct structures.
• Form I exhibited partial cis-trans isomerization upon photo-irradiation.
• Form II underwent [2+2] photodimerization and a photo-induced solid-to-liquid transition.
• Photomechanical responses varied with crystal morphology for Form I.

Conclusions:

• Demonstrated the ability to engineer distinct crystal polymorphs with tunable photochemical and photomechanical properties.
• Highlighted the potential of LSAM in designing functional molecular solids for advanced applications.
• Showcased unique photo-responsive behaviors, including isomerization, photodimerization, and phase transitions.