Ten new thiosemicarbazone derivatives, furan-2-carbaldehyde thiosemicarbazone (1), 3-methyl-furan-2-carbaldehyde thiosemicarbazone (2), 5-hydroxymethyl-furan-2-carbaldehyde thiosemicarbazone (3), 5-trifluoromethyl-furan-2-carbaldehyde thiosemicarbazone (4), 5-nitro-furan-2-carbaldehyde thiosemicarbazone (5), 5-phenyl-furan-2-carbaldehyde thiosemicarbazone (6), 5-(2-fluorophenyl)-furan-2-carbaldehyde thiosemicarbazone (7), 5-(4-methoxyphenyl)-furan-2-carbaldehyde thiosemicarbazone (8), 5-(1-naphthyl)-furan-2-carbaldehyde thiosemicarbazone (9), and 5-(1H-Pyrazol-5-yl)-furan-2-carbaldehyde thiosemicarbazone (10) were synthesized by condensing thiosemicarbazide with the respective furan-2-carbaldehyde in methanol. The prepared compounds were characterized by spectroscopic studies (FT-IR and NMR) and electrospray mass spectrometry. The molecular structures of 2, 6, 7, and 8 have also been determined by X-ray crystallography. Compounds 2, 6, and 7 crystallize in the E conformation about the N1-C6, N1-C11, and N1-C11 bonds, respectively, while 8 adopts the Z conformation about the N1-C12 bond with the presence of an intramolecular N2-HO2 hydrogen bond. All prepared thiosemicarbazone derivatives were evaluated for their in vitro antibacterial, antifungal, and antitumor activities against Staphylococcus aureus strains, Candida albicans/Candida tropicalis fungi, and seven human tumor cell lines (HuTu80, H460, DU145, M-14, HT-29, MCF-7, and LNCaP), respectively. The antioxidant activity was also studied by the DPPH assay. Compound 5 exhibited significant antibacterial activity against Staphylococcus aureus ATCC700699 (MIC=1μg/mL) compared to the nitrofurantoin and gentamicin reference drugs (MIC=125 and 10->100μg/mL, respectively). Compound 4 was ten times less active than amphotericin B (MIC=5μg/mL) against Candida albicans (ATCC90028 and ATCC10231), while 1 exhibited a moderate effect of scavenging of DPPH radical (IC₅₀=40.9μg/mL) in comparison to ascorbic acid reference compound (IC₅₀=22.0μg/mL). Among all the studied thiosemicarbazones, 5 showed a higher cytotoxic activity (IC₅₀=13.3627.73μ) in relation to the other tested compounds (IC₅₀=34.84>372.34μ) against all tested cell lines, except the LNCaP cell line, exhibiting its highest antiproliferative activity (IC₅₀=13.36μ) on the HuTu80cell line. Besides, 8 and 9 exhibited high antitumor activity (IC₅₀=13.31 and 7.69μ, respectively) against the LNCaP cells.

Mass spectrometry frequently reveals the existence of transient gas phase ions that have not been synthesized in solution or in bulk. These elusive ions are, therefore, often considered to be primarily of analytical value in fundamental gas phase studies. Here, we provide proof‐of‐concept that the products of ion‐molecule reactions in mass spectrometers may be collected on surfaces to generate condensed matter and thus serve as building blocks to synthesize new compounds. The highly reactive fragment anion [B₁₂Br₁₁]⁻ was generated in a mass spectrometer and converted to [B₁₂Br₁₁N₂]⁻ in the presence of molecular nitrogen followed by its mass‐selection and soft‐landing on surfaces. The molecular structure of [B₁₂Br₁₁N₂]⁻, which has not been synthetically obtained before, was confirmed by conventional methods of molecular analysis, including nuclear magnetic resonance and infrared spectroscopy. The [B₁₂Br₁₁N₂]⁻ ion is stable on surfaces and in solution at room temperature, but thermal annealing induces elimination of N₂ and provides access to the highly reactive intermediate [B₁₂Br₁₁]⁻ in the condensed phase, which can be further used as a reagent, for example, for electrophilic aromatic substitutions. Thus, isolation of [B₁₂Br₁₁N₂]⁻ expands the repertoire of the available diazo ions that can be employed as versatile intermediates in various chemical transformations.

Eight new thiosemicarbazone derivatives, 6-(1-trifluoroethoxy)pyridine-3-carbaldehyde thiosemicarbazone (1), 6-(4′-fluorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (2), 5-chloro-pyridine-3-carbaldehyde thiosemicarbazone (3), 2-chloro-5-bromo-pyridine-3-carbaldehyde thiosemicarbazone (4), 6-(3′,4′-dimethoxyphenyl)pyridine-3-carbaldehyde thiosemicarbazone (5), 2-chloro-5-fluor-pyridine-3-carbaldehyde thiosemicarbazone, (6), 5-iodo-pyridine-3-carbaldehyde thiosemicarbazone (7), and 6-(3′,5′-dichlorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (8) were synthesized, from the reaction of the corresponding pyridine-3-carbaldehyde with thiosemicarbazide. The synthesized compounds were characterized by ESI-Mass, UV-Vis, IR, and NMR (¹H, ¹³C, ¹⁹F) spectroscopic techniques. Molar mass values and spectroscopic data are consistent with the proposed structural formulas. The molecular structure of 7 has been also confirmed by single crystal X-ray diffraction. In the solid state 7 exists in the E conformation about the N2-N3 bond; 7 also presents the E conformation in solution, as evidenced by ¹H NMR spectroscopy. The in vitro antitumor activity of the synthesized compounds was studied on six human tumor cell lines: H460 (lung large cell carcinoma), HuTu80 (duodenum adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), M-14 (amelanotic melanoma), and HT-29 (colon adenocarcinoma). Furthermore, toxicity studies in 3T3 normal cells were carried out for the prepared compounds. The results were expressed as IC₅₀ and the selectivity index (SI) was calculated. Biological studies revealed that 1 (IC₅₀ = 3.36 to 21.35 μM) displayed the highest antiproliferative activity, as compared to the other tested thiosemicarbazones (IC₅₀ = 40.00 to >582.26 μM) against different types of human tumor cell lines. 1 was found to be about twice as cytotoxic (SI = 1.82) than 5-fluorouracile (5-FU) against the M14 cell line, indicating its efficiency in inhibiting the cell growth even at low concentrations. A slightly less efficient activity was shown by 1 towards the HuTu80 and MCF7 tumor cell lines, as compared to that of 5-FU. Therefore, 1 can be considered as a promising candidate to be used as a pharmacological agent, since it presents significant activity and was found to be more innocuous than the 5-FU anticancer drug against the 3T3 mouse embryo fibroblast cells.