Synthesis of Cu (II) and Zn (II) Complexes of a Quinoline Based Flexible Amide Receptor as Fluorescent Probe for Dihydrogen Phosphate and Hydrogen Sulphate and Their Antibacterial Activity.

A novel 8-hydroxy quinoline-derived amide receptor, in conjunction with its Cu (II) and Zn (II) complexes, has been strategically developed to function as remarkably efficient fluorescent receptors with a distinct capability for anion sensing. The comprehensive characterization of the synthesized compounds were achieved through UV-Vis, IR, NMR, and HRMS spectroscopic techniques. Among the Cu (II) and Zn (II) complexes, the latter exhibits superior selectivity for anions, specifically dihydrogen phosphate and hydrogen sulfate, as their tetrabutylammonium salts in a 9:1 acetonitrile-water (v/v) mixture. The Cu (II) complex demonstrates enhanced anion binding compared to the amide ligand, albeit with reduced selectivity. Furthermore, the affinity was evaluated using the Benesi-Hildebrand plot. The binding constants and Limit of Detection (LOD) for both complexes were precisely quantified. The Job plot illustrates a clear 1:1 binding interaction between the metal complexes and the guest anions. Significantly, both metal-complex receptors display a broad spectrum of antibacterial activity, against both gram-positive and gram-negative bacteria. It is worth highlighting that the Zn (II) complexed receptor outperforms the Cu (II) complexed receptor, as evidenced by its considerably lower Minimum Inhibitory Concentration (MIC) value against both bacterial strains.

ß-Cyclodextrin-Stabilized Biosynthesis Nanozyme for Dual Enzyme Mimicking and Fenton Reaction with a High Potential Anticancer Agent.

The myth of inactivity of inorganic materials in a biological system breaks down by the discovery of nanozymes. From this time, the nanozyme has attracted huge attention for its high durability, cost-effective production, and easy storage over the natural enzyme. Moreover, the multienzyme-mimicking activity of nanozymes can regulate the level of reactive oxygen species (ROS) in an intercellular system. ROS can be generated by peroxidase (POD), oxidase (OD), and Fenton-like catalytic reaction by a nanozyme which kills the cancer cells by oxidative stress; therefore, it is important in CDT (chemo dynamic therapy). Our current study designed to investigate the enzyme mimicking behavior and anticancer ability of cerium-based nanomaterials because the cerium-based materials offer a high redox ability while maintaining nontoxicity and high stability. Our group synthesized CeZrO4 nanoparticles by a green method using ß-cyclodextrin as a stabilizer and neem leaf extract as a reducing agent, exhibiting POD- and OD-like dual enzyme activities. The best enzyme catalytic activity is shown in pH = 4, indicating the high ROS generation in an acidic medium (tumor microenvironment) which is also supported by the Fenton-like behavior of CeZrO4 nanoparticles. Inspired by the high ROS generation in vitro method, we investigated the disruption of human kidney cells by this nanoparticle, successfully verified by the MTT assay. The harmful effect of ROS in a normal cell is also investigated by the in vitro MTT assay. The results suggested that the appreciable anticancer activity with minimal side effects by this synthesized nanomaterial.

Recognition of carboxylate anions and carboxylic acids by selenium-based new chromogenic fluorescent sensor: a remarkable fluorescence enhancement of hindered carboxylates.

A selenium metal-based new fluorescence sensor 5-pivaloylamino-1,2,5-selenodiazolo[3,4-d]pyrimidin-7-(6H)-one (receptor 1) has been reported for the recognition of monocarboxylic acids and carboxylate anions both by UV-vis and fluorescence methods. Receptor 1 recognizes carboxylate anions more than monocarboxylic acids and it is a selective sensor for carboxylates with specially hindered carboxylate anions. The changes of fluorescence intensity are remarkably enhanced with red shift in presence of bulky carboxylate anions. The X-ray crystal structure of receptor 1 with pivalic acid has been reported.

1,2-Di-2-quinolylethene.

The title compound, C(20)H(14)N(2), comprises two crystallographically independent centrosymmetric mol-ecules (A and B) with different conformations due to the disorder of molecule B. The whole of mol-ecule B is disordered over two sets of positions, corresponding to a 180° rotation of the molecule, with a site-occupancy ratio of 0.780 (6):0.220 (6). The minor component of the disordered part in B has the same configuration as mol-ecule A, but the major component is different. The dihedral angle between the planes of mol-ecule A and mol-ecule B (major component) is 63.22 (3)°. The crystal structure is stabilized by inter-molecular C-H⋯π inter-actions.

N-[6-(Dibromo-meth-yl)-2-pyrid-yl]-2,2-dimethyl-propionamide.

In the mol-ecular structure of the title compound, C(11)H(14)Br(2)N(2)O, the dimethyl-propionamide substituent is twisted slightly with respect to the pyridine ring, the inter-planar angle being 12.3 (2)°. The dibromo-methyl group is orientated in such a way that the two Br atoms are tilted away from the pyridine ring. In the crystal structure, mol-ecules are associated into supra-molecular chains by weak C-H⋯O inter-actions. The crystal is further stabilized by weak N-H⋯Br and C-H⋯N inter-actions.

A second monoclinic polymorph of 2-amino-4,6-dichloro-pyrimidine.

The title chloro-substituted 2-amino-pyrimidine, C(4)H(3)Cl(2)N(3), is a second monoclinic polymorph of this compound which crystallizes in the space group C2/c. The structure was previously reported [Clews & Cochran (1948 ▶). Acta Cryst. 1, 4-11] in the space group P21/a. There are two crystallographically independent mol-ecules in the asymmetric unit and each mol-ecule is planar. The dihedral angle between the two pyrimidine rings is 30.71 (12)°. In the crystal structure, mol-ecules are linked via N-H⋯N inter-molecular hydrogen bonds, forming infinite one-dimensional chains along the a axis. These hydrogen bonds generate R(2) (2)(8) ring motifs. The chains are stacked along the b axis.

2-(7-Hydr-oxy-2-naphth-yloxy)-N-(6-methyl-2-pyrid-yl)acetamide.

In the title compound, C(18)H(16)N(2)O(3), the dihedral angle between the naphthalene ring system and the pyridyl ring is 18.1 (8)°. The mol-ecules are inter-connected via C-H⋯O and O-H⋯O hydrogen bonds. Inversion-related mol-ecules are linked by O-H⋯O hydrogen bonds into cyclic centrosymmetric R(2) (2)(22) dimers. Intra-molecular N-H⋯O hydrogen bonding produces an S(5) ring motif. The crystal structure is further stabilized by weak C-H-π inter-actions.