This virtual collection is a celebration. It is a celebration of crystallography in Africa, and a celebration of the international crystallography community. It commemorates the founding of the African Crystallographic Association (AfCA), which was accepted as the newest Regional Associate of the International Union of Crystallography (IUCr) in 2023, the year of the 75th anniversary of the first IUCr Congress and General Assembly. The collection contains research articles authored by scientists across the African continent, as well as a selection of articles giving context to crystallography in Africa. These discuss history, collaboration between scientists and between associations, and various educational and outreach initiatives.

This paper summarizes brief perspectives on the historic process of establishing an African Crystallographic Association (AfCA), including appropriate role players, organizations and accompanying events. It concludes with the official admission of AfCA as the fifth Regional Associate of the IUCr at the 26th Congress and General Assembly of the IUCr in Melbourne, Australia in 2023.

In the title coumarin derivative, the dihedral angle between the 2H-chromen-2-one ring system and the phenyl ring is 89.12 (5)°. In the crystal, the mol­ecules are linked by C—H⋯O hydrogen bonds into [010] double chains.

The African Light Source project towards a light source for the African continent is described.

The synthesis and structures are reported of two transition-metal complexes involving 2-(2-hy­droxy­phen­yl)benzimidazole with cobalt and manganese, arising from a UK–Africa collaboration.

A detailed analysis of rhenium(I) organometallic covalent binding to a model protein is conducted at seven time points over 38 weeks. Changes in the protein structure induced at the Re binding sites over the time series as well as the relationship between the proximity of the solvent channels to the residues containing the highest-occupied Re are described.

The title benzimidazole com­pounds were synthesized by the condensation reaction of benzene-1,2-di­amine with 4-meth­oxy­naph­tha­lene-1-carbaldehyde in the ratios 1:1 and 1:2, respectively. Both com­pounds exhibit significant anti­corrosion properties with respect to iron and copper.

The hydrazone form is the predominant form in the solid state. The naphthol and benzene fragments attached to the –N=N– moiety adopt the s-trans conformation. There are only two types of inter­molecular inter­actions in the crystal structure: strong hydrogen-bonding C—H⋯O inter­actions and π–π stacking inter­actions.

N-(5-Acetyl-4-methyl­pyrimidin-2-yl)benzene­sulfonamide was synthesized and structurally characterized. In the crystal, π–π inter­actions between the phenyl and pyrimidine groups of neighbouring mol­ecules form mol­ecular chains parallel to [010]. Adjacent chains are linked by N—H⋯N hydrogen-bonding inter­actions, resulting in a three-dimensional network.

Two benzyl­idenehydrazinederivatives have been synthesized and structurally characterized.

The title Schiff base was synthesized by the reaction of 2-amino-4-methyl­phenol with 4-meth­oxy­naph­tha­lene-1-carbaldehyde in a 1:1 ratio. The com­pound exhibits significant anti­corrosion properties for iron and copper.

In the crystal of the title com­pound, C—H⋯O hydro­gen bonds link the mol­ecules, enclosing (10) and (16) ring motifs, into layers almost parallel to the bc plane. The layers are further connected by π–π stacking inter­actions.

The title triazene derivatives were synthesized using a diazo­nium inter­mediate that was obtained from 3-amino­pyridine and isoamyl nitrite.

The orthophosphate BaNi₂Fe(PO₄)₃ crystallizes in the α-CrPO₄ type of structure, in which edge-sharing [Ni₂O₁₀] octa­hedra are linked to PO₄ tetra­hedra and [FeO₆] octa­hedra to form a three-dimensional framework delimiting channels which house disordered Ba²⁺ cations.

Four cocrystals containing N′-(butan-2-yl­idene)pyridine-4-carbohydrazide and one cocrystal containing N′-iso­propyl­ideneisonicotinohydrazide were synthesized by reacting isoniazid with either butan-2-one (for the former) or acetone (for the latter). The coformers used to synthesize these cocrystals were 2,4-di­hydroxy­benzoic acid, 2,5-di­hydroxy­benzoic acid, 2-chloro-4-nitro­benzoic acid and 1-naphthoic acid. The cocrystals were characterized by SC-XRD, PXRD and DSC.

In the title compound, a (3,−1) critical point is found on the topology path connecting the (PhO)₃P=O and SnPh₃Cl moieties, showing that an actual O—Sn covalent bond is formed between the phosphate and the stannane derivatives.

In the layer structure of di-μ₂-iodido-bis­[(2,2′-bi­quinoline-κ²N,N′)copper(I)], π–π inter­actions provide conectivity within and between the layers.

The asymmetric unit of the title compound consists of two mol­ecules differing to a small degree in their conformations. In the crystal, layers of mol­ecules are connected by weak C—H⋯O hydrogen bonds and slipped π-stacking inter­actions.

The successful synthesis, characterization and analysis of inter­molecular inter­actions of aryl­sul­fon­amide Schiff bases have been achieved, alongside their evaluation for inhibitory effects on tankyrase poly(ADP-ribose) polymerase in the context of colon cancer, through in-silico testing.

The mol­ecular structure of the title compound comprises an essentially planar pyrimidine ring from which the propynyl group is rotated by 15.31 (4)°. In the crystal, a tri-periodic network is formed by N—H⋯O, N—H⋯N and C—H⋯O hydrogen-bonding and slipped π–π stacking inter­actions, leading to narrow channels extending parallel to the c axis.

The pendant dodecyl chain in the title compound adopts an all-trans conformation apart from the gauche terminal C—C—C—Br moiety.

In the title compound, the thia­zine ring exhibits a screw-boat conformation. In the crystal, corrugated layers of mol­ecules parallel to the ab plane are formed by N—H⋯O and C—H⋯O hydrogen bonds together with C—H⋯π(ring) and S=O⋯π(ring) inter­actions. The layers are connected by additional C—H⋯O hydrogen bonds and π-stacking inter­actions.

The title mol­ecule adopts a conformation resembling a two-bladed fan with the octyl chains in fully extended conformations. In the crystal, the mol­ecules are linked by C—H⋯O and C—H⋯N hydrogen bonds and C—H⋯π inter­actions.

In the title compound, the benzimidazole moiety subtends dihedral angles of 46.16 (7) and 77.45 (8)° with the benzene rings, which themselves form a dihedral angle of 54.34 (9)°. The crystal structure features O—H⋯N and O—H⋯O hydrogen-bonding inter­actions, which together lead to the formation of two-dimensional hydrogen-bonded layers parallel to the (101) plane, as well as π–π inter­actions

The transition-metal orthophosphate, β-Cd₃(PO₄)₂, was synthesized by a solid-state reaction and characterized by single-crystal X-ray diffraction and EDS spectroscopy. It crystallizes in the monoclinic system, space group P2₁/n.

Mol­ecules of the title complex are centrosymmetric and the Fe—N bond lengths to the N atoms of the porphyrin ring indicate that the Fe^II atom is in the low-spin state.

In the crystal, mol­ecules of the title compound are linked into infinite sinusoidal chains along the [001] direction. The study demonstrated that dispersion energy was the most influential factor in the crystal organization of the compound.

In the title Schiff base tetra­nuclear copper(II) complex, two discrete environments are present in the structure: CuN₂OBr₂ and CuBr₄. Two copper(II) cations are situated in distorted square-based pyramidal environment, while two copper(II) cations are located in distorted tetra­hedral geometry.