Substantiation to structure-property of pyrazine-based compounds by undeniable impress of its different connectivities

On the importance of π-stacking interactions in the complexes of copper and zinc bearing pyridine-2,6-dicarboxylic acid N-oxide and N-donor auxiliary ligands

Using N- and O-donor ligands in a mixed-ligand system, three new coordination complexes have been X-ray characterized, exhibiting strong π–π stacking interactions.

Broadening the scope of high structural dimensionality nanomaterials using pyridine-based curcuminoids

We present a new heteroditopic ligand (3pyCCMoid) that contains the typical skeleton of a curcuminoid (CCMoid) decorated with two 3-pyridyl groups. The coordination of 3pyCCMoid with ZnII centres results in a set of novel coordination polymers (CPs) that display different architectures and dimensionalities (from 1D to 3D). Our work analyses how synthetic methods and slight changes in the reaction conditions affect the formation of the final materials. Great efforts have been devoted toward understanding the coordination entities that provide high dimensional systems, with emphasis on the characterization of 2D materials, including analyses of different types of substrates, stability and exfoliation in water. Here, we foresee the great use of CCMoids in the field of CPs and emphasize 3pyCCMoid as a new-born linker.

Efficient dispersive micro solid-phase extraction of antidepressant drugs by a robust molybdenum-based coordination polymer

A molybdenum-based coordination polymer {[Mo(PDA)(NO)(μ-O)MoO₃]·1.42H₂O·0.58C₂H₅OH}_n (1) (PDA is 1,10-phenanthroline-2,9-dicarboxylate) was synthesized using solvothermal reaction conditions and characterized using a suite of analytical techniques. Single-crystal X-ray diffraction studies reveal a 1D chain structure, with close contacts expanding the structure into 3D including π-interactions and hydrogen bonding. The utility of 1 as a sorbent for dispersive micro solid-phase extraction (D-μSPE) of basic organic compounds such as antidepressants is supported by the presence of many functional groups on the surface of 1 (such as pendant carboxylates, Mo=O, Mo-NO, and CH groups) as well as extensive electrostatic interactions. Therefore, 1 can be a suitable choice as sorbent in the D-μSPE of antidepressant drugs from human plasma samples via appreciable adsorbate-adsorbent interactions. Determination of the extracted antidepressant drugs was conducted using high-performance liquid chromatography-ultraviolet (HPLC-UV), with calibration plots being linear in the concentration range 0.1-500 ng mL^-1 for amitriptyline and nortriptyline, 0.2-500 ng mL^-1 for imipramine, and 0.5-300 ng mL^-1 for sertraline. The relative standard deviation (RSD) values were calculated for both intra-day and inter-day precision, and the RSD% values were in the range 3.9 to 5.2% and 4.6-5.4%, respectively. The limits of detection (LODs) was determined as 0.03-0.2 ng mL^-1. Due to the good stability and reusability of the sorbent, the adsorption capacity had no obvious decrease after being used 20 times. Finally, the D-μSPE-HPLC-UV method was applied for the determination of antidepressant drugs in human plasma samples with recoveries of the analytes in the range 94.9 to 102%. The article describes the synthesis of a robust molybdenum-based coordination polymer, and its application as sorbent for dispersive micro solid-phase extraction of antidepressant drugs from human plasma samples.

Molecular Interactions of Pyrazine-Based Compounds to Proteins

Pyrazine-based compounds are of great importance in medicinal chemistry. Due to their heteroaromatic nature, they uniquely combine properties of heteroatoms (polar interactions) with the properties of aromatic moieties (nonpolar interactions). This review summarizes results of a systematic analysis of RCSB PDB database focused on important binding interactions of pyrazine-based ligands cocrystallized in protein targets. The most frequent interaction of pyrazine was hydrogen bond to pyrazine nitrogen atom as an acceptor, followed by weak hydrogen bond with pyrazine hydrogen as donor. We also identified intramolecular hydrogen bonds within pyrazine ligands, π-interactions, coordination to metal ions, and few halogen bonds in chloropyrazines. In many cases the binding mode of the pyrazine fragment was complex, involving a combination of several interactions. We conclude that pyrazine as a molecular fragment should not be perceived as a simple aromatic isostere but rather as a readily interacting moiety of drug-like molecules with high potential for interactions to proteins.