Development of Energetic Azidopurines and Their Congeners

Prof. Dr. Māris Turks

Azidopurines and their azide-substituted fused pyrimidine congeners that are regarded as purine isosteres from medicinal chemistry point of view have been known for several decades. Such azido-heterocycles that possess azido-azomethine structural entity have been studied due to several aspects: 1) they undergo dynamic azide-tetrazole equilibrium in solution phase and this has been reviewed [https://doi.org/10.1007/s10593-019-02574-7]; 2) azido group as pseudohalide displays properties of a leaving group in the S_NAr reactions [https://doi.org/10.1055/s-0040-1706568]; 3) rich chemistry of azido substituent offers further modification possibilities [https://doi.org/10.1002/9780470682517], which are extensively used by medicinal and bioorganic chemists.

On the other hand, polyazidopyrimidines have been recognized as high-energy compounds for several decades [https://doi.org/10.1002/anie.200602778] and are still actively reached to achieve the best possible ratio between the intrinsically opposite properties: high stored energy and low sensitivity. For recent research on energetic pyrimidine derivatives, see: [https://doi.org/10.1039/D2TA02042D; https://doi.org/10.1016/j.molstruc.2021.130732; https://doi.org/10.1016/j.cej.2020.126514 ]. Also, the fused heterocycles possessing azido and nitro substituents are studied as energetic materials [https://doi.org/10.1039/C9TA12704F].

However, to the best of our knowledge there is no systematic study on energetic potential and sensitivity of such synthetically common derivatives as 2,6-diazidopurine, 2,6,8-triazidopurine, 2,4-diazidoquinazoline, 2,4,n-triazidoquinazoline, 2,4-diazido-n-nitro-quinazoline, 2,4-diazidopyrido[2,3-d]pyrimidine, 2,4,n-triazidopyrido[2,3-d]pyrimidine, 2,4-diazido-n-nitro-pyrido[2,3-d]pyrimidine and their further azido and/or nitro derivatives. Therefore, we propose to combine the synthetic organic chemistry skills of Latvian team with renown expertise in energetic compounds of German team and photophysical analysis skills of various heterocycles by Lithuanian team to make a systematic study and to establish the energetic profile of the aforementioned azidopurines and their congeners.

1. 1. Synthesis of azido-derivatives of purines and their congeners: Riga Technical University, Riga, Latvia; February-September 2023.
2. Evaluation of energetic properties of the products obtained in Riga: Ludwig Maximilian University of Munich, Germany; April 2023.
3. Elaboration of luminescent detection/analysis methods of the compounds obtained in Riga and experiments on their probable UV photolysis: Vilnius University, Vilnius, Lithuania; February-September 2023.
4. Prof. Turks lecture on purine chemistry: Ludwig Maximilian University of Munich, Germany; 28 February 2023.
5. Prof. Klapötke’s invited lecture at the annual scientific conference of Riga Technical University in the section “Materials Science and Applied Chemistry”: Riga Technical University, Riga, Latvia; 20. October 2023.
6. Manuscript preparation for the collaborative publication and co-project application preparation: at the universities mentioned above, supported by regular Zoom meetings.

Direct: 66 people in total

Prof. Turks’s scientific group in Riga: 23 people

Prof. Klapötke scientific group in Munich: 28 people

Prof. Jursenas scientific group in Vilnius: 15 people

Indirect: 700-850 people in total

RTU Faculty of Materials Science and Applied Chemistry: 250-300 students in chemistry branch

Community of organic chemists in Latvia: 400-500 people

Institute of Photonics and Nanotechnology at Vilnius University: 55 people