Chem4Energy: a consortium of the Royal Society Africa Capacity-Building Initiative.

The Africa Capacity-Building Initiative is a Royal Society programme funded by the former UK Department for International Development to develop collaborative research between scientists in sub-Saharan Africa and the UK. Initially, four institutions were involved in the Chem4Energy consortium: Cardiff University in the UK and three African partners, the Kwame Nkrumah University of Science and Technology, Ghana, the University of Namibia and the University of Botswana, soon also including the Botswana International University of Science and Technology. The Chem4Energy research programme focused on 'New materials for a sustainable energy future: linking computation with experiment', aiming to deploy the synergy between state-of-the-art computational and experimental techniques to design and optimize new catalysts and semiconductor materials for renewable energy applications, based on materials that are abundant and readily available in African countries. The Chem4Energy consortium has achieved ambitious research goals, graduated seven PhD students and delivered a high-quality cross-disciplinary training programme in materials science and simulation techniques relevant to renewable energy applications. Since 2021, the extended consortium, including North-West University and the Centre for High-Performance Computing in South Africa, has remained active through an annual Chem4Energy conference series, with the sixth meeting taking place in Namibia in April 2025.

Physico-functional and nutritional characteristics of germinated pigeon pea (Cajanus cajan) flour as a functional food ingredient.

The study investigated the effect of germination on pigeon pea flour's physico-functional (pH, color, water and oil absorption capacities, swelling and foaming capacities and bulk densities) and proximate, total polyphenols and antioxidant activity. The physico-functional and proximate parameters were determined using standard protocols. The color analysis showed that germination significantly increased the flour samples' lightness (L*) (70.7; p = 0.009) by almost 1.5-fold. Germination resulted in almost 1.1 times higher oil absorption capacity than the control (219.9%; p = 0.022). The foaming capacity of the germinated samples significantly (p = 0.015) increased by 6.4%. Germination significantly reduced the loose bulk density (0.54 vs 0.63; p = 0.012) but significantly increased the tapped bulk density (0.84 vs 0.77; p = 0.002). The germinated samples recorded significantly (1.62%; p = 0.010) lower crude fat, about 1.2 times lower than the raw flour. Germination significantly increased the flour's total ash (4.2% vs 3.6%; p = 0.003) and crude protein (11.6% vs 9.4%; p = 0.047) content. Germinated pigeon pea flour will perform better in formulating baked products, aerated foods and food extenders than non-germinated pigeon pea flour. Hence, the germination of pigeon peas should be encouraged because it harnesses the functional and proximate attributes measured.

A DFT Mechanistic Study on Base-Catalyzed Cleavage of the ß-O-4 Ether Linkage in Lignin: Implications for Selective Lignin Depolymerization.

The detailed mechanism of the base-catalyzed C-C and C-O bond cleavage of a model compound representing the ß-O-4 linkage in lignin is elucidated using DFT calculations at the M06/6-31G* level of theory. Two types of this linkage have been studied, a C2 type which contains no γ-carbinol group and a C3 type which contains a γ-carbinol. Cleavage of the C2 substrate is seen to proceed via a 6-membered transition structure involving the cation of the base, the hydroxide ion and the α-carbon adjacent to the ether bond. The reaction with KOH has the lowest activation barrier of 6.1 kcal mol-1 with a calculated rate constant of 2.1 × 108 s-1. Cleavage of the C3 substrate is found to proceed via two pathways: an enol-formation pathway and an epoxide-formation pathway. The first path is the thermodynamically favored pathway which is similar to the pathway for the C2 substrate and is the preferred pathway for the isolation of an enol-containing monomer. The second path is the kinetically favored pathway, which proceeds via an 8-membered transition state involving a hydrogen hopping event, and is the preferred pathway for the isolation of an epoxide-containing monomer. The KOH-catalyzed reaction also has the lowest activation barrier of 10.1 kcal mol-1 along the first path and 3.9 kcal mol-1 along the second path, with calculated rate constants of 2.4 × 105s-1 and 8.6 × 109s-1 respectively. Overall, the results provide clarity on the mechanism for the base-catalyzed depolymerization of lignin to phenolic monomers. The results also suggest both NaOH and KOH to be the preferred catalysts for the cleavage of the ß-O-4 linkage in lignin.

1,3-Dipolar [3 + 2] cycloaddition reactions of N,C,C-trisubstituted nitrones with ring-acceptor methylenecyclopropanes: a computational study.

BACKGROUND: 1,3-Dipolar [3 + 2]-cycloaddition of nitrones to the carbon-carbon double bonds of methylenecyclopropanes yields a mixture of regioisomeric 4- and 5-isoxazolidines. The mechanisms of the reactions of N,C,C-trisubstituted nitrones with ring acceptor substituted dimethyl methylenecyclopropanes-1,2-dicarboxylate and aryl methylidene cyclopropanes-1,1-dicarboxylate have been investigated with the Becke 3-Parameter Lee-Yang-Par exchange-correlation functional, a Hartree-Fock DFT hybrid functional, to delineate the factors responsible for the regioselectivity of these class of reactions. FINDINGS: The energetics of the reaction of the phenyl-substituted nitrone with unsubstituted methylenecyclopropane indicate that the formation of the 5-spirocyclopropane is favored over the 4-spirocyclopropane kinetically and thermodynamically. However, the energetics of the reaction of the same phenyl nitrone with vicinal ester (-CO2CH3)-substituted methylenecyclopropane show an inversion in the regioselectivity favoring the formation of the 4-regioisomer over the 5-regioisomer. For the reactions of N,C,C-trisubstituted nitrone with vicinal ester (-CO2CH3)-substituted methylenecyclopropane (-R1=H, -R2=Ph and -R1=CH3 and -R2=CO2CH3) and geminal ester (-CO2CH3)-substituted methylenecyclopropane (R3=H, R4=H; R3=OCH3, R4=CH3; and R3=H, R4=Cl), the energetics indicate that the 5-spirocyclopropane is favored over the 4-spirocyclopropane. The calculations also indicate that electron-donating groups increase regioselectivity of the 5-regioisomers over the 4-regioisomers. CONCLUSION: The regioselectivity of these reactions is determined by both electronic and steric factors. The pathways with the lower activation barrier leads to the more stable regioisomer in all cases, implying that the pathways that are kinetically favored are also thermodynamically favored. However, it is also clear from the energetics that these reactions are not reversible and are therefore under kinetic control. Therefore the selectivity of the reactions is governed solely by the difference in activation barriers leading to the two isomers and not in any way by the thermodynamic stability of the isomers formed.