Discussions on decolonizing the curriculum are common in Humanities and Social Science Faculties but still rare in the Physical Sciences. In this commentary, we describe the work we have conducted to begin decolonizing and diversifying our undergraduate chemistry curriculum. We also discuss what it means to decolonize chemistry and reflect on why it is an important thing to do. Finally, we discuss a number of different strategic approaches that could be followed to decolonize an undergraduate chemistry curriculum.

We present the first study to measure the dissociative photochemistry of 2-thiouracil (2-TU), an important nucleobase analogue with applications in molecular biology and pharmacology. Laser photodissociation spectroscopy is applied to the deprotonated and protonated forms of 2-TU, which are produced in the gas-phase using electrospray ionization mass spectrometry. Our results show that the deprotonated form of 2-thiouracil ([2-TU-H]−) decays predominantly by electron ejection and hence concomitant production of the [2-TU-H]· free-radical species, following photoexcitation across the UVA-UVC region. Thiocyanate (SCN−) and a m/z 93 fragment ion are also observed as photodecay products of [2-TU-H]− but at very low intensities. Photoexcitation of protonated 2-thiouracil ([2-TU·H]+) across the same UVA-UVC spectral region produces the m/z 96 cationic fragment as the major photofragment. This ion corresponds to ejection of an HS· radical from the precursor ion and is determined to be a product of direct excited state decay. Fragment ions associated with decay of the hot ground state (i.e., the ions we would expect to observe if 2-thiouracil was behaving like UV-dissipating uracil) are observed as much more minor products. This behaviour is consistent with enhanced intersystem crossing to triplet excited states compared to internal conversion back to the ground state. These are the first experiments to probe the effect of protonation/deprotonation on thionucleobase photochemistry, and hence explore the effect of pH at a molecular level on their photophysical properties.

Near threshold photoexcitation of iodide–thiouracil clusters explores the coupling of nucleobase centred excitations onto the electron detachment spectrum.

Laser photodissociation spectroscopy of the I -•guanine complex has been conducted for the first time across the regions above the electron detachment threshold to explore the excited states and whether vertical ionization occurs from the iodide or the nucleobase.The photofragment spectra reveal a prominent dipole-bound excited state (I) close to the calculated vertical electron detachment energy (~4.0 eV) and a second excited (II) centred around 4.8 eV, which we assign to -* nucleobase-localized transitions. The ionic photofragments are identified as Iand I -•[G-H], with the later fragment being produced significantly more strongly than the former. Both photofragments are observed across the two excited states, with production of the iodide being attributed to internal conversion to the ground state followed by evaporation. We trace the formation of the I -•[G-H] photofragment to initial vertical ionization of guanine, followed by ejection of a proton. This two-step process is important as it follows known steps in radiation-induced damage to DNA, namely initial formation of a guanine radical cation which then forms a free radical [G-H] moiety through deprotonation. Production of the I -•[G-H] photofragment is pronounced through II indicating that its formation is enhanced by coupling of the -* transitions to the electron detachment continuum.

In our taught chemistry curricula, the majority of individuals who are used to illustrate historical aspects of chemistry topics are white, western chemists. Decolonizing the undergraduate chemistry curricula is increasingly recognized as an important step toward developing a more inclusive higher-education environment for students from minoritized ethnic backgrounds. Here, we provide the first openly accessible resource that provides examples of both individual scientists and groups that can be used to illustrate chemistry teaching, and hence provide role model examples of scientists from different cultures. More generally, the resource provides a significant body of examples for chemistry educators to use as they begin working toward decolonizing their curricula.