Fisher johns apparatus

The selected thiosemicarbazide derivatives, characterised by the most potent affinity towards human DNA topoisomerase II, were synthesised using previously described method¹⁴ (link). In brief, equimolar amounts of respective acid hydrazides and isothiocyanates were dissolved in anhydrous ethanol and heated under reflux for 10 min. After cooling, the precipitate formed were filtered, dried and crystallised from anhydrous ethanol. Melting temperatures of the synthesised compounds were measured using Fisher-Johns apparatus (Fisher Scientific, Schwerte, Germany). Elemental analyses were determined using AMZ-CHX elemental analyser (PG, Gdansk, Poland) and were within ±0.4% of the theoretical values. NMR spectra were recorded on a Bruker Avance spectrometer (Bruker BioSpin GmbH, Germany) using DMSO-d₆ as solvent and TMS as an internal standard. FT-IR spectra were recorded using a Vertex 70 spectrometer (Bruker) equipped with an ATR Platinum Diamond A 225 device. All reagents and solvents were purchased from Sigma-Aldrich and were used without further purification.

All reagents used for the experiments were purchased from Sigma-Aldrich (Munich, Germany) and Merck Co. (Darmstadt, Germany) and used without further purification. They had a class of the purity declared by the manufacturer. The melting points of the obtained compounds were determined with a Fisher–Johns apparatus (Fisher Scientific, Schwerte, Germany), without any correction. The purity of the compounds obtained was assessed through thin layer chromatography (TLC) on plates covered with silica gel (aluminum oxide 60 F-254) by Merck. Chloroform-ethanol mixtures in the ratio 10:1 (v/v) were used as the mobile phase. Spots were developed by irradiation with UV light with a wavelength λ = 254 nm. FT-IR spectra were recorded on a Nicolet 6700 spectrometer (Thermo Scientific, USA); in cm⁻¹. ¹H and ¹³C NMR spectra were recorded on the Bruker Avance 300 and 600 apparatus (Bruker BioSpin GmbH, Hamburg, Germany). The compounds were dissolved in dimethyl sulfoxide (DMSO-d₆) for analysis. Tetramethylsilane (TMS) was used as an internal standard. Chemical shift values are given in ppm. Then elemental analyses were determined by a Perkin Elmer 2400 series II CHNS/O analyzer (PerkinElmer, Waltham, MA, USA), and the results were within ±0.4% of the theoretical value.

Melting points were determined using Fisher-Johns apparatus (Fisher Scientific, Schwerte, Germany) and were not corrected. The ¹H NMR and ¹³C NMR spectra were recorded by a Bruker Avance 300 MHz instrument using DMSO-d₆ as solvent and TMS as an internal standard. Chemical shifts were expressed as δ (ppm). MS using atmospheric pressure chemical ionisation (APCI) was recorded on a Bruker MicroTOF II mass spectrometer. APCI settings were as follows: vaporiser temperature, 350 °C; drying gas temperature, 180 °C; drying gas flow, 4 l/min; and nebuliser pressure, 2 bar. The purity of the compounds was checked by TLC on plates with silica gel Si 60 F₂₅₄, produced by Merck Co. (Darmstadt, Germany). Elemental analyses were performed by AMZ 851 CHX analyser and the results were within ±0.4% of the theoretical value.

All reagents used for the experiments were purchased from Merck Co. (Darmstadt, Germany) and used without further purification. They had a class of the purity declared by the manufacturer. The melting points of the obtained compounds were determined with a Fisher–Johns apparatus (Fisher Scientific, Schwerte, Germany), and presented without any correction. The NMR spectra were recorded on the Bruker Avance 700 MHz apparatus (Bruker BioSpin GmbH, Ettlingen, Germany). The compounds were dissolved in dimethyl sulfoxide (DMSO-d6) before analysis. Tetramethylsilane (TMS) was used as an internal standard. Chemical shift values were given in ppm.

All reagents and solvents used in this research were purchased from Sigma-Aldrich (Munich, Germany) and Merck Co. (Darmstadt, Germany) and used without further purification. Thin layer chromatography (TLC) on plates covered with silica gel (aluminum oxide 60 F-254, Merck Co.) was used to check the purity of the obtained compounds and to monitor the progress of the reaction. Chloroform-ethanol mixture in the 10:1 (v/v) ratio was used as the mobile phase. The spots were detected by irradiation with UV light at a wavelength of λ = 254 nm. ¹H NMR and ¹³C NMR spectra were recorded on the Bruker Avance 300 and 600 apparatus (Bruker BioSpin GmbH, Germany). The melting points of the obtained compounds were measured with a Fisher-Johns apparatus (Fisher Scientific, Germany), and presented without any correction. The elemental analysis was determined by the Perkin Elmer 2400 series II CHNS/O analyzer (Waltham, MA, USA), and the results were within ± 0.4% of the theoretical value.

All commercial reactants and solvents were purchased from either Alfa Aesar (Kandel, Germany) or Sigma-Aldrich (St. Louis, MO, USA) with the highest purity and used without further purification. The melting points were determined by using Fisher-Johns apparatus (Fisher Scientific, Schwerte, Germany) and are uncorrected. The purity of the compounds was checked by TLC on plates with silica gel Si 60F₂₅₄, produced by Merck Co. (Darmstadt, Germany). The ¹H-NMR and ¹³C-NMR spectra were recorded by a Bruker Avance 300 MHz instrument using DMSO-d6 as solvent and TMS as an internal standard. Chemical shifts were expressed as δ (ppm). Elemental analyses were performed by AMZ 851 CHX analyzer and the results were within ±0.4% of the theoretical value.

Melting points were measured on a Fisher-Johns apparatus (Fisher Scientific Company, Pittsburgh, PA, USA) and are uncorrected. Optical rotations were measured on a 323 polarimeter (Perkin Elmer Inc., London, UK). Ultraviolet absorptions were recorded on a UV 160U spectrophotometer (Shimadzu, Kyoto, Japan). IR spectra were obtained on a Tensor 27 spectrometer (Bruker, Ettlingen, Germany). The 1D and 2D NMR experiments were performed on a Bruker Advance III spectrometer (Bruker) at 400 MHz for ¹H and 100 MHz for ¹³C. Chemical shifts were referenced to TMS and J values are given in Hz. The HRDARTMS data were recorded on an AccuTOF JMS-T100LC mass spectrometer (Jeol Ltd., Tokyo, Japan). Prep TLC was carried out on precoated Sil G/UV254 plates (Macherey Nagel, Düren, Germany) of 1.0 mm thickness. Silica gel 230–400 mesh (Macherey-Nagel), Sephadex LH-20 (Pharmacia Biotech AB, Uppsala, Sweden) and octadecyl functionalized silica gel (Sigma Aldrich, St. Louis, MO, USA) were used for column chromatography. The X-ray data were collected on a D8 Venture κ-geometry diffractometer (Bruker).