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Different supramolecular motifs are formed by the crystallisation of amino-substituted derivatives of quinoxaline, pyrimidine and pyridazine. These were made from the corresponding mono- or dichlorinated heterocycles by a nucleophilic displacement reaction. The pyridine-type nitrogen atoms activate the chlorine atoms because they can stabilise a negative charge, which forms when the amine attacks the ring. One amino group can be attached under mild conditions in hot ethanol or acetonitrile, but the first then deactivates the ring so the second requires more forceful conditions using a pressure vessel at 150 °C. Butylamine is frequently used because it reduces the polarity of the product, making it easier to purify and isolate. The extended structure of the quinoxaline derivatives 16–18 show a common 'pincer' hydrogen-bond motif, with a quinoxaline nitrogen atom accepting two N–H···N hydrogen bonds, giving a spiral or helical axis. The chain symmetries are 41, 21 and 31, respectively, depending on the substituents. A stereoview of each is shown. The pyrimidine derivatives 19, 12, 20, 14 and 21 form hydrogen-bonded tapes and compound 20 forms inversion dimers. [ABSTRACT FROM AUTHOR]

2,4-Difluoronitrobenzene has been reacted with a linker diamine (ethylenediamine or propylenediamine) and butylamine, in either order, to give new molecular building blocks for porous supramolecular networks. Two structures were established by X-ray single crystal structure determinations. The propylenediamine structure displays small pores, which may be due to the longer and more flexible linker in the structure. [ABSTRACT FROM AUTHOR]

Five historical green dyes from the Historische Farbstoffsammlung, Technical University of Dresden, have been analysed by liquid chromatography – mass spectrometry (LC-MS). The dyes were determined to be formed by the alkylation of either crystal violet or rosaniline and contained both doubly and singly charged ions. One sample had a spread of higher molecular weight doubly charged ions reminiscent of the alkylation of a Hofmann violet. Malachite green was the dye present in one sample. [ABSTRACT FROM AUTHOR]

A radical approach to late-stage functionalization using photoredox and Diversinate™ chemistry on the Open Source Malaria (OSM) triazolopyrazine scaffold (Series 4) resulted in the synthesis of 12 new analogues, which were characterized by NMR, UV, and MS data analysis. The structures of four triazolopyrazines were confirmed by X-ray crystal structure analysis. Several minor and unexpected side products were generated during these studies, including two resulting from a possible disproportionation reaction. All compounds were tested for their ability to inhibit the growth of the malaria parasite Plasmodium falciparum (3D7 and Dd2 strains) and for cytotoxicity against a human embryonic kidney (HEK293) cell line. Moderate antimalarial activity was observed for some of the compounds, with IC50 values ranging from 0.3 to >20 µM; none of the compounds displayed any toxicity against HEK293 at 80 µM. [ABSTRACT FROM AUTHOR]