The synthesis of dioxadiazuliporphyrinogen 7 and its oxidized forms: dioxadiazuliporphyrin 8 and dication 8(2+), is reported. These compounds were characterized in solution using UV-vis and 1H and 13C NMR spectroscopic means and in the solid state via single-crystal X-ray diffraction analysis. Dioxadiazuliporphyrin is a nonaromatic porphyrinoid, readily and reversibly oxidizable to its cation radical and to the aromatic carbaporphyrinoid dication, which can be viewed as a 21,23-dicarba-22,24-dioxaporphyrin with two fused tropylium rings. Further insight into the geometric and magnetic manifestations of aromaticity and antiaromaticity in the case of the redox couple 8, 8(2+) is obtained using density functional calculations and nucleus-independent chemical shifts.

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The resolution of stereoisomers of C21-alkylated nickel(II) complexes of N-confused porphyrin (NCP) was performed by means of chiral-phase HPLC with an effectiveness of above 90 % molar ratio for each isomer. The reverse signs of the Cotton effects in the circular dichroism (CD) spectra of the separated fractions are indicative of the pair of enantiomers. The application of low-temperature 2D NMR methods to the separated diastereomers of the system comprising a chiral 2-(S)-methylbutyl substituent, in connection with the CD spectra and relative HPLC migration rates, allowed the assignment of the absolute configuration of the chiral C21-substituted complexes of NCP. The assignment was confirmed by time-dependent DFT (TDDFT) calculations of CD spectra for the C21-methylated nickel(II) complex. The system remains chiral after removal of the metal ion from the macrocyclic crevice, despite the fact that this demetalation is connected with a change of the C21 hybridization from pyramidal to trigonal. The retention of chirality was established by means of CD spectra and confirmed by TDDFT calculations for a C21-methylated NCP free base. Stereoisomers were also separated for three covalently linked bis(NCP) systems with bridges involving one or two C21 carbon atoms. The occurrence of a pair of enantiomers was established for nonsymmetrical dimers comprising only one stereogenic center. In the case of the 21,21'-(o-xylene)-linked dimer, three stereoisomers, that is, a pair of enantiomers and an optically inactive meso-form, were separated and analyzed by CD and (1) H NMR spectroscopy. The stereoisomers of a diastereoselectively formed nonsymmetrical chloroplatinum(II)-linked dimer, consisting of heterochiral C21-alkylated NCP nickel(II) subunits, after separation displayed a strong optical activity, which can be ascribed to the rigid helical structure of the complex.

Purpose The aim of the study was to present the spectroscopic characteristics and crystal structure of the etazene—a benzimidazole opioid, which appeared on the illegal drug market in Poland in the last weeks. Methods The title compound was analyzed by X-ray crystallography as well as gas and liquid chromatography combined with mass spectrometry. Spectroscopic techniques have also been used, such as nuclear magnetic resonance, infrared and ultraviolet-visible spectroscopies. Results We presented the identification and the broad chemical characterization of etazene, a synthetic opioid that has recently been introduced on the illegal drug market. Conclusions In this paper, we described single-crystal X-ray, chromatographic and spectroscopic characterization of a synthetic opioid that emerged on the new psychoactive substance (NPS) market in Poland. To the best of our knowledge, this is the first full characterization of etazene. Analytical data presented in the work can be helpful in identification and detection of the NPS in forensic and clinical laboratories.

The protonation of 3,3'-bis(meso-tetratolyl-2-aza-21-carbaporphyrin) with various acids was studied. The stepwise formation of mono-, di-, and tetracationic species was shown on the basis of UV-vis-near-IR and low-temperature (1)H NMR. Upon going from di- to tetraprotonated form, the bis(porphyrinoid) skeleton changes its conformation from cisoid to bent-transoid, which was found by single-crystal X-ray analyses, 2D NMR, and density functional theory (DFT) calculations. The formation of cation-anion complexes was established in both the solid state and solution. The substitution of anions was studied by spectrophotometric and (1)H NMR titrations. A pronounced decrease of the HOMO-LUMO gap in the tetraprotonated species was shown by cyclovoltametry and time-dependent DFT calculations.