Diazirine photodissociation and solvent effects

• Main Author: Goh, Chen Yee
• Other Authors: Terry W.J. Steele
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/166671
• Institution: Nanyang Technological University

Carbene-based bioadhesive, CaproGlu involves the use of UVA active trifluoromethyl phenyl diazirine (TPD) as a precursor for reactive carbene to provide adhesion property. However, photolysis of TPD generates both diazoalkane and carbene species in ratio of 35:65. The effects of how solvent polarity and temperature can be used to tune the ratio of product generated during photolysis of CaproGlu is still unknown and will be investigated in this project. CaproGlu was dissolved in solvents of varying polarity and irradiated with 365nm UVA wavelength at different temperatures.19F NMR spectroscopy was used to analyse the content in the sample before and after every 10 J of UVA dose, ratio of diazoalkane/carbene (DA/C) were calculated based on NMR integral value. Ratio of DA/C generated at the end of 50 J of UVA dose is in the order DMSO-d6> triacetin> propylene carbonate> δ-valerolactone. The results showed no correlation between DA/C ratio and solvent polarity. Although an increase in temperature is shown to affect DA/C ratio, the effects varied in different solvents. The accelerated rate of depletion of diazirine in propylene carbonate and δ-valerolactone sample resulted in complete depletion of diazirine within 50 J of UVA dose, not attainable in DMSO-d6 (control) sample. The ability to tune DA/C ratio allows the moderation of cross-linking density desired for bioadhesive application.