By the condensation of thiosemicarbazide with coumarin aldehyde, two novel substituted thiosemicarbazones with chemical formulae C24H25N3O3S (3a) and C26H23N3O3S (3b) have been synthesized. The synthesized compounds were resolved using SC-XRD, and structure elucidation was carried out using 1H NMR, 13C NMR, UV–visible, and FT-IR spectroscopic analyses. Computational calculations at the B3LYP/6-311+G­(d,p) level of theory were performed to countercheck the experimental (UV–vis, FT-IR) findings and explore the electronic (FMO, NBO, MEP) properties of 3a–b. The nonlinear optical (NLO) properties of 3a–b were estimated using B3LYP, HF, LC-BLYP, CAM-B3LYP, M062X, and M06 functionals in combination with the 6-311+G­(d,p) basis set. The crystallographic data revealed that compounds were crystallized as an orthorhombic crystal lattice with the Pbcn space group and the triclinic crystal lattice with the P̅1 space group. A good concurrence among experimental SC-XRD-generated bond lengths, bond angles, FT-IR, UV–vis, and corresponding DFT results was found, which confirms the purity of both compounds. The NBO analysis confirmed the presence of intramolecular hydrogen bonding and hyperconjugative interactions, which not only were the pivotal cause of stability of the investigated compounds but also led to an overwhelming NLO response. The energy differences calculated for HOMO/LUMO are 3.053 and 3.118 eV in 3a and 3b, respectively. The crystal 3b showed a higher value of first-order polarizability at all levels of theory than 3a. Overall results show that the crystals under investigation are polarized in nature with a good dipole moment. A comparative analysis with urea molecules clearly indicates that the studied compounds are acceptable NLO candidates and they can be used for future technological applications.

High toxicity and extensive accessibility of fluoride and cyanide ions in diverse environmental media encouraged attention for scheming well-organized probes for their detection. Keeping in mind we have designed and synthesized thiosemicarbazone-based chemosensors RB-1, RB-2 and RB-3 for the detection of fluoride and cyanide ions. The structural elucidation of the synthesized chemosensors is done by employing different analytical techniques including nuclear magnetic resonance and electronic absorption specrtoscopies. Admirable detection limit, binding constant and fast response time (2 s) to F− and CN− ions enlarged the applications of these chemosensors. Additional confirmation of the sensing ability of these chemosensors is derived from DFT and TDDFT calculations with M06/6-311G(d,p) method by performing FMO, UV–Vis, QTAIM and global reactivity parameters elucidation. Overall results point out that investigated chemosensors are suitable candidates for sensing the F− ions. These chemosensors were successfully applied to detect F− ions in a commercial toothpaste sample.

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Inhibiting α‐glucosidase is a reliable method for reducing blood sugar levels in diabetic individuals. Several novel chromen‐linked hydrazine carbothioamide (3a–r) were designed and synthesized by condensation of chromone‐3‐carbaldehyde with a variety of substituted thiosemicarbazides. The structures of these new analogues were elucidated through various advanced spectroscopic techniques (1H NMR, 13C NMR, and ESI‐MS). The resulted compounds were screened for α‐glucosidase inhibitory potential and all the compounds (3a–r) exhibited potent inhibition of α‐glucosidase with IC50 values ranging 0.29–53.70 µM. Among them compounds 3c, 3f, 3h, and 3r displayed the highest α‐glucosidase inhibitor capability with IC50 values of 1.50, 1.28, 1.08, and 0.29 µM, respectively. Structure–activity relationship showed that different substituted groups are responsible for the variation in the α‐glucosidase inhibition. The kinetics studies of the most active inhibitor (3r) were performed, to investigate the mode of inhibition and dissociation constants (Ki), that indicated a competitive inhibitor with Ki value of 1.47 ± 0.31 µM. Furthermore, molecular docking studies was performed to reveal the possible interactions, such as H‐bonding, or π–π stacking, with the key residues of α‐glucosidase. Docking analysis revealed the importance of hydrazine carbothioamide moiety of compounds in the attachment of ligands with the crucial residues of α‐glucosidase. The estimated pharmacokinetic, physicochemical, and drug likeness properties of compounds 3a–r reflects that these molecules have acceptable range of these properties.