Oxalic Acid, a Versatile Coformer for Multicomponent Forms with 9-Ethyladenine

Six new multicomponent solids of 9-ethyladenine and oxalic acid have been detected and characterized. The salt screening has been performed by mechanochemical and solvent crystallization processes. Single crystals of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer molar ratio were obtained by solution crystallization and elucidated by single-crystal X-ray analysis. The supramolecular interactions observed in these solids have been studied using density functional theory (DFT) calculations and characterized by the quantum theory of “atoms in molecules” (QTAIM) and the noncovalent interaction plot (NCIPlot) index methods. The energies of the H-bonding networks observed in the solid state of the anhydrous salts in 1:1 and 2:1 nucleobase:coformer are reported, disclosing the strong nature of the charge assisted NH···O hydrogen bonds and also the relative importance of ancillary C–H··O H-bonds.

Rapid Bacterial Recognition over a Wide pH Range by Boronic Acid-Based Ditopic Dendrimer Probes for Gram-Positive Bacteria

We have developed a convenient and selective method for the detection of Gram-positive bacteria using a ditopic poly(amidoamine) (PAMAM) dendrimer probe. The dendrimer that was modified with dipicolylamine (dpa) and phenylboronic acid groups showed selectivity toward Staphylococcus aureus. The ditopic dendrimer system had higher sensitivity and better pH tolerance than the monotopic PAMAM dendrimer probe. We also investigated the mechanisms of various ditopic PAMAM dendrimer probes and found that the selectivity toward Gram-positive bacteria was dependent on a variety of interactions. Supramolecular interactions, such as electrostatic interaction and hydrophobic interaction, per se, did not contribute to the bacterial recognition ability, nor did they improve the selectivity of the ditopic dendrimer system. In contrast, the ditopic PAMAM dendrimer probe that had a phosphate-sensing dpa group and formed a chelate with metal ions showed improved selectivity toward S. aureus. The results suggested that the targeted ditopic PAMAM dendrimer probe showed selectivity toward Gram-positive bacteria. This study is expected to contribute to the elucidation of the interaction between synthetic molecules and bacterial surface. Moreover, our novel method showed potential for the rapid and species-specific recognition of various bacteria.

Synthesis of Adenine-based Fluorescent and Naked-eye Chemosensors: Specific DNA Probes for the Detection of Bacterial Pathogens

A rapid and confident tool to identify and diagnose bacterial pathogens with more accuracy using DNA as fingerprints is necessary. Herein, we report a smart chemosensor having a terminal adenine sticking to the thymine of single-stranded DNA (ssDNA) through supramolecular interactions and, which leaves ssDNA when the same ssDNA matches with the targeting desired DNA. We have synthesized a naked-eye coloured chemosensor with carbazole. As a model genetic material, DNA of Clavibacter michiganensis subsp. michiganensis was hybridized to ssDNA and immobilized over nitrocellulose membrane. The prepared adenine-chemosensor, by passing through the nitrocellulose-ssDNA membrane caused the formation of ssDNA nitrocellulose-ssDNA-adenine-chemosensor. FTIR results of the immobilized ssDNAs showed that the matching of same ssDNA releases the adenine-chemosensor from the surface of nitrocellulose-ssDNA that results in formation of the double stranded DNA. The selectivity of chemosensor was also confirmed with different bacterial DNA (Bacillus subtilis) as control. These data highlights accurate and reliable results of a new diagnostic kit prototype promising for further studies, which is able to diagnose DNA quickly and precisely.

Synthesis, Crystal Structure and Theoretical Investigations of (3-(2-Chlorophenyl)-5-Tosyl-1,3,3a,4,5,9b-Hexahydroisoxazolo[4,3-c]Quinolin-3a-yl)Methanamine

In the title compound (3-(2-chlorophenyl)-5-tosyl-1,3,3a,4,5,9b-hexahydroisoxazolo[4,3-c]quinolin-3a-yl)methanamine (3-CPTHIQM), the Thorpe–Ingold effect causes the S atom's tetrahedral geometry to be deformed, with O-S-O and N-S-C angles diverging from ideal tetrahedral values. The crystal packing features C—H⋯O hydrogen-bond inter¬actions.The supramolecular interactions were confirmed and quantified using Hirshfeld surface analysis. Quantum chemical calculations of sulfonamide are calculated at DFT/B3LYP/6-311++G(d,p) basis set. The NLO properties were calculated at the same level of theory. Furthermore, frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP) surfaces were calculated and analyzed in detail. In a molecular docking study, the investigated sulfonamide compound is evaluated as a new potential cancer inhibitor.

Synthesis, Magnetic Property and Assembly Studies of Two Cu(II) Complexes Based on o-phenanthroline and Phosphate

Using newly precipitated Cu(OH)2, o-phenanthroline and phosphoric acid as raw materials, two complicated Cu(II) compounds were obtained by one-pot method. They are double-nuclear Cu(II) 1, {[Cu2(phen)2(H2PO4)3][Cu2(phen)2(H2O)(H2PO4)3]}·2H2PO4·5H2O, and mononuclear Cu(II) 2, [Cu(phen)2(H2PO4)]4·4H3PO4·2HPO4·6H2O. The crystal structure analysis showed that the copper phosphate reacted with the neutral ligand o-phenanthroline to obtain the compounds with different structures. Phosphoric acid can exist in various forms in copper complexes, such as H3PO4, (H2PO4)1-, (HPO4)2-, and form a rich and colorful supramolecular interaction with water molecules. Hirschfeld surface analysis gives the types and regions of molecular interactions in crystals. It is of scientific significance to understand the reaction between transition metal phosphate and organic neutral ligand. The thermogravimetric and magnetic properties of compounds 1 and 2 were also reported. Magnetic analysis shows that supramolecular interactions and dipole-dipole interactions have great influence on the magnetic properties of two compounds. CCDC: 20565681 for 1; 2090334 for 2.