TY - JOUR

T1 - Photolytic Studies of Norbornadiene Derivatives under High-Intensity Light Conditions

AU - Kjaersgaard, Alexander

AU - Hölzel, Helen

AU - Moth-poulsen, Kasper

AU - Nielsen, Mogens Brøndsted

PY - 2022/10/6

Y1 - 2022/10/6

N2 - The photoconversion of a norbornadiene (NBD) derivative was studied under high-intensity mono- and polychromatic light conditions at high concentrations. The photoisomerization quantum yield (ϕNBD→QC), proceeding from NBD to its quadricyclane (QC) isomer, was determined using a tunable OPO laser and a solar simulator light source. The solar simulator was designed to mimic the AM1.5G solar spectrum between 300 and 900 nm. Using the OPO laser, ϕNBD→QC was measured at discrete values between 310 and 350 nm in steps of 10 nm, and a variation between 0.81 and 0.96 was observed. Weighting these values of ϕNBD→QC with the spectral profile of the solar simulator, an averaged value of 0.87 ± 0.03 was obtained. Determination of ϕNBD→QC was also performed directly in the solar simulator providing a value of 0.97 ± 0.14, in good agreement with the weighted values from the OPO. Photoisomerization quantum yields were found to decrease slightly at higher concentrations. At high concentrations, we found that correcting for the presence of QC was important due to similar absorption coefficients of the NBD and QC isomers at the absorption tail. Cyclability of the forward and backward NBD/QC conversion was studied over several cycles. The NBD/QC couple exhibited excellent thermal stability, but a slight photodegradation per cycle was observed, increasing with the concentration of the sample. This result indicates that the molecules undergo some intermolecular reactions.

AB - The photoconversion of a norbornadiene (NBD) derivative was studied under high-intensity mono- and polychromatic light conditions at high concentrations. The photoisomerization quantum yield (ϕNBD→QC), proceeding from NBD to its quadricyclane (QC) isomer, was determined using a tunable OPO laser and a solar simulator light source. The solar simulator was designed to mimic the AM1.5G solar spectrum between 300 and 900 nm. Using the OPO laser, ϕNBD→QC was measured at discrete values between 310 and 350 nm in steps of 10 nm, and a variation between 0.81 and 0.96 was observed. Weighting these values of ϕNBD→QC with the spectral profile of the solar simulator, an averaged value of 0.87 ± 0.03 was obtained. Determination of ϕNBD→QC was also performed directly in the solar simulator providing a value of 0.97 ± 0.14, in good agreement with the weighted values from the OPO. Photoisomerization quantum yields were found to decrease slightly at higher concentrations. At high concentrations, we found that correcting for the presence of QC was important due to similar absorption coefficients of the NBD and QC isomers at the absorption tail. Cyclability of the forward and backward NBD/QC conversion was studied over several cycles. The NBD/QC couple exhibited excellent thermal stability, but a slight photodegradation per cycle was observed, increasing with the concentration of the sample. This result indicates that the molecules undergo some intermolecular reactions.

U2 - 10.1021/acs.jpca.2c03583

DO - 10.1021/acs.jpca.2c03583

M3 - Journal article

C2 - 36149432

VL - 126

SP - 6849

EP - 6857

JO - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory

JF - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory

SN - 1089-5639

IS - 39

ER -