Anthracenes are an important class of acenes. They are being utilized more and more often in chemistry and materials science, due to their unique rigid molecular structure and photoreactivity. In particular, photodimerization can be harnessed for the fabrication of novel photoresponsive materials. Photoreactions between the same anthracenes have been investigated and utilized in various fields, while reactions between varying anthracenes have barely been investigated. Here, Nuclear Magnetic Resonance (NMR) spectroscopy is employed for the investigation of the photodimerization of two exemplary anthracenes: anthracene (A) and 9-bromoanthracene (B), in the solutions with only A or B, and in the mixture of A and B. Estimated k values, derived from the presented kinetic model, showed that the dimerization of A was 10 times faster in comparison with B when compounds were investigated in separate samples, and 2 times faster when compounds were prepared in the mixture. Notably, the photoreaction in the mixture, apart from AA and BB, also yielded a large amount of the AB mixdimer. The investigation of a mixture with different anthracenes can deliver relative reactivity under the same experimental conditions. This results in a better understanding of the photoisomerization processes, which is essential for the practical utilization of the photodimerization of anthracenes. --------------------------------------------------------------------------------------------------------------------------------------------------------- The study employs 400 MHz 1H-NMR spectroscopy for the investigation of the photodimerization of two exemplary anthracenes: anthracene (A) and 9-bromoanthracene (B) in the solutions with only A or B and in the mixture of A and B. Experiments were performed using different concentrations and oxygenation level of the sample. CD2Cl2 was used as a solvent. Given data include eight 1H-NMR experiments processed by TopSpin 4.0.7 software of: 4.5 mM of A (File: 1_A_concentration I.fid.zip) 2.25 mM of A (File: 2_A_concentration II.fid.zip) 2.25 mM of A with oxygen (File: 3_A_concentration II_Oxygen.fid.zip) 4.5 mM of B (File: 4_B_concentration I.fid.zip) 2.25 mM of B (File: 5_B_concentration II.fid.zip) 2.25 mM of B with oxygen (File: 6_B_concentration II_Oxygen.fid.zip) Mixture of A and B with molar mixing ratio 1:1.3 (File: 7_Mixture_ratio I.fid.zip) Mixture of A and B with molar mixing ratio 1:2.3 (File: 8_Mixture_ratio II.fid.zip) -------------------------------------------------------------

The dataset is part of a project that has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 847413. Scientific work published as part of an international co-financed project founded from the program of the Minister of Science and Higher Education entitled "PMW" in the years 2020 - 2024; agreement no. 5005/H2020-MSCA-COFUND/2019/2, PD2PI 13.