Spectroscopic investigations and molecular docking analysis of ML115: A potential molecular probe of the signal transducer and activator of transcription

Herein, we described the investigation of ML115 as molecular probe of the signal transducer and activator of transcription (STAT3), through organic synthesis, X-ray diffraction and theoretical calculation. Firstly, ML115 was prepared and the single crystal was obtained by slow evaporation method. Single crystal X-ray diffraction study revealed that ML115 possesses monoclinic crystal system having P 21/n space group. Then the conformations were optimized and vibrational spectrum were predicted through density functional theory (DFT), and compared with the crystal structure and experimental results. The vibrational modes were interpreted in terms of potential energy distribution, and molecular electrostatic potentials analysis was carried out to predict the reactive sites of ML115 for electrophilic and nucleophilic attack. Accordingly, the stabilization of the molecular structure was revealed by the frontier orbitals analysis. Furthermore, ML115 was docked into STAT3 pocket to elucidate the mechanism of the agonistic activity. The work would be helpful for understanding the feature of ML115 as molecular probe of STAT3, and thus provide hint for discover more STAT3 probes.