Rophosphate to [Tf2The has been assured by HPLC-MS as no residues of (1) has been synthesized N-] perfluoroheptyl 1,two,4-oxadiazolylpyridine precursor the precursor counterions were detected. following the classical methodology in the amidoxime route (Yield = 48 ) [18,19]. The3.two. Thermotropic Liquid Crystalline Phase Behavior The thermotropic liquid crystalline phase behavior of the salts has been characterized working with a mixture of differential scanning calorimetry (DSC) and polarized opticalAppl. Sci. 2021, 11,6 ofregioisomer (2) together with the reciprocal position of your perfluoroheptyl chain as well as the 4-pyridyl group with respect for the heteroaromatic core has been prepared based on the ANRORC method having a yield of 86 [20]. The quaternization reactions of those precursors have already been carried out to receive the series of perfluoroheptyl 1,two,4-oxadiazolylpyridinium salts (1a-c and 2a-c) by direct alkylation in acetonitrile with suitable alkylating agents. For this, 1-iododecane, 1-bromododecane and 1-bromotetradecane happen to be selected. The success in the quaternization at the pyridine nitrogen of compounds 1 and two towards 1a-c and 2a-c (Scheme 1) was assessed by 1 H-NMR (reported inside the SI) and mass spectrometry (MS). Yields as much as 93 have already been obtained of the desired goods. The metathesis from 1a’ -c and 2a-c with iodide and bromide or hexafluorophosphate (1a’, synthesis and analytical information reported MRTX-1719 Histone Methyltransferase Within the SI, Figure S9) as counter ions has been realized in methanol and addition with the new desired counterion, right here bis(trifluoromethane)sulfonimide lithium salt. Filtration and washing with water yielded the preferred solutions 1d-f and 2d-f (Scheme two). Detection on the new DMPO In Vitro counterion bis(trifluoromethane)sulfonimide ([Tf2 N- ]) has been performed by way of HPLCMS inside a adverse mode. Complete conversion from iodide/bromide/hexafluorophosphate to [Tf2 N- ] has been guaranteed by HPLC-MS as no residues with the precursor counterions were detected. three.2. Thermotropic Liquid Crystalline Phase Behavior The thermotropic liquid crystalline phase behavior on the salts has been characterized using a mixture of differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The DSC analyses have been carried out at first to get a clear picture in regards to the thermal behavior of the samples. Afterwards, POM was utilized to examine the samples very cautiously to establish the mesophase forms exhibited by the samples. Starting with the precursor perfluoroheptyl 1,2,4-oxadiazolylpyridium salts with iodide or bromide as counterion, the melting points for 1a-c and 2b-c couldn’t be determined within the DSC traces, indicating decomposition before melting–except for sample 2a. Moreover, no melting points have been observed during the POM analyses, indicating that these salts decompose at temperatures greater than 200 C. Within the prior study in regards to the salts containing 1,two,4-oxadiazole connected by way of its C(five) or C(three) to an N-methylated 4pyridyl moiety plus a perfluoroheptyl chain, a demethylation reaction was experimentally observed, which can be probably through a retro SN two mechanism [10]. Similarly, this has been reported for imidazolium halides and could justify the instability at larger temperatures of the alkylated salts 1a-c and 2b-c obtaining iodide and bromide as counterion [21]. Only the salt 2a with iodide because the counter ion possesses an ionic liquid crystalline phase behavior inside the POM analysis at the same time as within the DSC traces. Nevertheless, that is not additional discussed a.