The important role of pyrazine (pz) and its derivatives in fields such as biochemistry and pharmacology, as well as in the study of magnetic properties, is surveyed. Recognition of these properties without extensive investigations into their structural properties is not possible. This review summarizes interactions that exist between these organic compounds by themselves in the solid state, as well as those in coordination polymers with metal ions and in polyoxometalatebased hybrids. Complexes based on pyrazine ligands can generate metal-organic framework (MOF) structures that bind polyoxometalates (POMs) through covalent and noncovalent interactions. Some biological and magnetic properties involving these compounds are considered and the effect of hydrogen bonding on their supramolecular architectures is highlighted. feature articles 232 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds Acta Cryst. (2019). C75, 231-247 feature articles 234 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds Acta Cryst. (2019). C75, 231-247 feature articles Acta Cryst. (2019). C75, 231-247 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds 237 Figure 9Structure of [Cu 2 (PZOAPZ-H)Br 3 (H 2 O) 2 ]. Reproduced from Grove et al. (2004) with permission. feature articles Acta Cryst. (2019). C75, 231-247 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds 245

Lacunary polyoxometalates (LPOMs) are key precursors for the synthesis of functional POMs. To date, reviews dedicated to behavioral studies of LPOMs often comprise the role of metal ions, including transition metal (TM) and rare earth (RE) ions, in extending and stability of high-nuclearity clusters. In contrast, the role of organic ligands in the structures and properties of lacunary-based hybrids has remained less explored. In this review, we focus on the role of organic fragments in the self-assembling process of POM-based architectures and discuss relationships between the nature and structure of organic ligand and properties such as the topology of hybrid inorganic–organic material in RE and TM-RE heterometallic derivatives of lacunary Keggin-type POMs. The effects of organic fragment in mixed ligand hybrids are also briefly reviewed.

: (±)-Indolizidine 209D is one of the alkaloids isolated from the skin secretions of certain neotropical frogs and exhibit a range of pharmacological properties, including blocking neuromuscular transmission. Therefore, the synthesis of indolizidine 209D and more complex derivatives, have been the subject of several publications. The preparation pathways of indolizidine 209D and its derivatives are the subject of this review. In this paper, some highly regio- and stereoselective functionalization process was reviewed through the synthesis of the optically active (±)-indolizidine 209D.

Background: Salmonella enterica has become increasingly resistant to antimicrobial agents, partly as a result of genes carried by integrons. Objective: The aim of the present study was to investigate the prevalence of class 1 and 2 integrons and resistance to antimicrobial agents in clinical isolates of S. enterica. Methods: This study included all Salmonella isolates, recovered from patients with salmonellosis, admitted to Medical Children Hospital, Tehran, Iran during 2015-2016. Bacterial isolates were identified using standard biochemical and agglutination tests. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute guidelines. The presence of class 1 and 2 integrons was investigated by Polymerase Chain Reaction (PCR) assay, using specific primers. Results: A total of 138 Salmonella strains were isolated and included in this study. Integrons were detected in 45 (32%) isolates. Class 1 and 2 integrons were detected in 24 (17.3%) and 21 (15.2%) isolates, respectively. All integron-positive isolates showed multidrug-resistant phenotypes. Resistance to more than three antimicrobial agents was observed in integron-positive isolates. Conclusions: Our findings showed that integrons were widely distributed among S. enterica isolates in Tehran. Class 1 integrons are more prevalent than class 2 integrons in Salmonella isolates, and there is an association with MDR patterns. Therefore, these integrons are more likely to be involved in the distribution of resistant phenotypes in Salmonella strains.

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