X-Ray structure, Hirshfeld analysis and DFT studies of two new hits of triazolyl-indole bearing alkylsulfanyl moieties

Two new hits of triazolyl-indole containing two different alkylsulfanyl analogues named tert-butyl 2-((4-amino-5-(1H-indol-2-yl)-4H-1,2,4-triazol-3-yl)thio)acetate 2, and ethyl 2-((4-amino-5-(1H-indol-2-yl)-4H-1,2,4-triazol-3-yl)thio)acetate 3 were synthesized via reaction of 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione 1 with tert-butyl bromoacetate and ethyl chloroacetate in the presence of base (Et3N). The molecular structure of 2, and 3 was confirmed by single-crystal X-ray diffraction and 1H/13C- NMR spectroscopic techniques. In compound 2, the molecular packing depends on significant O...H (9.3%), N...H (12.4%) and S...H (3.1%) as well as relatively weak C...H (14.1%), S...C (2.1%), H...H (50.5%) and S...S (0.9%) contacts. Similarly, the strong O...H (11.0-12.3%) and N...H (13.1-13.6%) hydrogen bonds as well as weak C...H (15.3-16.4%), S...N (0.8-1.7%) and H...H (43.6-43.9%) are the most important interactions compound in 3. Both compounds are polar molecules where hit 2 (0.980 Debye) is less polar than 3 analogue (5.029 Debye). The atomic charge distribution and molecular electrostatic potential map as well as the reactivity descriptors were also discussed. The calculated NMR and UV-Vis spectra of the studied compounds were computed and compared with the experimental data. The different σ→σ*, π→π*, n→σ* and n→π* donor-acceptor interactions were investigated using NBO analysis.