Physical–Spectroscopic Study of Charge-Transfer Complexes of Some Purine Derivatives with (π) and (σ) Electron Acceptors. Iraqi Journal of Science [Internet]. 2024 Jan. 26 [cited 2025 Mar. 31];54(4. Appendix):994-1002. Available from: https://ijs.uobaghdad.edu.iq/index.php/eijs/article/view/12410