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Herein, we describe the synthesis, structural elucidation, and DNA interaction of newly synthesized Cu(II) and Zn(II) complexes, i.e., [Cu(SB)(L-trp)(H 2 O) 2 ]NO 3 (1) and [Zn(SB)(L-trp)(H 2 O) 2 ]NO 3 (2) (SB = Schiff base obtained from the reaction between o-vanillin and 2-amino-2-methylpropane-1,3-diol; L-trp = L-tryptophan). From the analysis, a six-coordinated environment around the Cu(II) or Zn(II) center is proposed. The ability of the complexes to bind with calf thymus DNA was examined by optical spectroscopy (UV-vis titrations and steady-state fluorescence emission) and viscosity measurements. The vivid experimental results revealed that complexes 1 and 2 avidly bind to DNA through surface and groove binding modes, albeit with dissimilar intrinsic binding constants (1.54 × 10 4 and 1.36 × 10 4 M -1 for 1 and 2, respectively). Both complexes can displace ethidium bromide (EB) to some extent from the intercalated EB-DNA system, resulting in fluorescence quenching. Additional experiments such as [Fe(CN) 6 ] 4- -induced quenching and thermal melting confirmed the electrostatic and groove binding mode. Furthermore, molecular docking studies verified that both complexes locate in the DNA minor groove by surface binding and were stabilized through weak intermolecular forces. The binding affinity of the lowest energy docked pose was found to be -5.37 kcal/mol for complex 1 and - 5.18 kcal/mol for complex 2. The present work is expected to pave the way for the synthesis of DNA-targeting Cu(II)/Zn(II) metal complexes for the development of chemotherapeutic agents., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A new Zn(II)-based coordination polymer (1) comprising the Schiff base ligand obtained by the condensation of 5-aminosalicylic acid and salicylaldehyde has been synthesized. This newly synthesized compound has been characterized by analytical and spectroscopic methods, and finally, by single-crystal X-ray diffraction technique in this study. The X-ray analysis reveals a distorted tetrahedral environment around the central Zn(II) center. This compound has been used as a sensitive and selective fluorescent sensor for acetone and Ag+ cations. The photoluminescence measurements indicate that in the presence of acetone, the emission intensity of 1 displays quenching at room temperature. However, other organic solvents caused meagre changes in the emission intensity of 1. Additionally, the fluorescence intensity of 1 has been examined in the presence of different ketones viz. cyclohexanone, 4-heptanone, and 5-nonanone, to assess the interaction between the C=O group of the ketones and the molecular framework of 1. Moreover, 1 displays a selective recognition of Ag+ in the aqueous medium by an enhancement in its fluorescence intensity, representing its high sensitivity for the detection of Ag+ ions in a water sample. Additionally, 1 displays the selective adsorption of cationic dyes (methylene blue and rhodamine B). Hence, 1 showcases its potential as an excellent luminescent probe to detect acetone, other ketones, and Ag+ with an exceptional selectivity, and displaying a selective adsorption of cationic dye molecules. [ABSTRACT FROM AUTHOR]

New complex [Mn (SB)2(DMF)2] [W (CN)8] hereafter referred to as complex 1, which was prepared by self–assembly of [Mn (SB)2(DMF)2]3+ and [W (CN)8]3− and structurally characterized by elemental analysis, infrared (IR) and single crystal X–ray techniques (H2SB is Schiff base derived from the condensation of salicylaldehyde and N,N–diethylethylenediamine and DMF is dimethylformamide). The structure consists of 1–D supramolecular chains and further stacks to give a 3–D supramolecular architecture whose molecular fragments are linked by hydrogen bond as well as C − H···π interactions between [Mn (SB)2(DMF)2]3+ and [W (CN)8]3−. An underlying net for the representation consists of two types of fragments with 1,4 M5–1 and 1,8 M9–1 topologies and further illustration of the molecular network in terms of a graph−theory approach using simplification procedure resulted in the underlying net of 2C1topological type in the complex 1. Magnetic susceptibility measurements of complex 1 was carried out in the temperature range 2–300 K, indicates the presence of either magnetic anisotropy zero field splitting, the effect of intramolecular interactions, or both. Complex 1 follows the Curie–Weiss law with Curie constant value of 3.43 cm3mol−1K, and the slight negative Weiss constant (−0.60 K) value indicates the predominant antiferromagnetic magnetic exchange interactions. The magnetic properties of Title complex was investigated thoroughly and showed that ferromagnetic interaction between W(V) and Mn (III) operate via the intramolecular H–bonding interaction between cyanide nitrogens and a hydrogen atom. [ABSTRACT FROM AUTHOR]

• Three isomeric Zn(II) pyridyl imine complexes synthesized and characterized. • These complexes used as sensitizers and co-sensitizers with N719 dye • The isomer having 4-pyridyl group displayed best sensitization and co-sensitization properties. • The electron injection mechanism has been addressed using DOS calculations. Three new isomeric Zn(II) complexes derived from pyridine based Schiff bases synthesized by condensation of pyridine-2-carboxyaldehyde and three positional isomers 2-amino pyridine (2-Py-Zn), 3- amino pyridine (3-Py-Zn) and 4-amino pyridine (4-Py-Zn). The synthesized ligands and their Zn(II) complexes have been characterized by microanalyses, FT-IR, multinuclear NMR, UV-Vis and emission spectroscopy. These newly synthesized isomeric complexes have been used as the sensitizers as well as co-sensitizers with state-of-the-art N719 dye in dye sensitized solar cells (DSSCs). Amongst all three isomeric complexes, the DSSC assembly fabricated with 4-Py-Zn/ N719 dye shown best performance with an overall photon-to-current conversion efficiency (PCE) of 6.52% with IPCE of 44%. The obtained co-sensitization results are better in comparison to the DSSC fabricated using only N719 (η = 4.22%; IPCE = 45%) under identical condition. Three new positional isomeric d10-based Zn(II) pyridyl imine sensitizers synthesized and their application as co-sensitizer in DSSC with state of the art N719 dye explored. [Display omitted] [ABSTRACT FROM AUTHOR]

A mononuclear Zn(II) complex of (Zn(H2L) (CH3OH) Cl2) (1) has been synthesized by using a nonlinear optically active Zwitterionic Schiff base which is 4-((2-hydroxy-3-methoxybenzylidene) amino) benzoic acid (H2L). Complex 1 has been structurally analyzed by FTIR and UV spectroscopy, TGA, Powder-XRD and single crystal X-ray diffraction. X-Ray crystallographic studies revealed Zn(II) complex crystallizes in a P21/c space group and exists in a distorted trigonal bipyramidal geometry (τ = 0.68). The topological analysis of complex 1 showed that the underlying net is characterized by an unknown topological type and point symbol {342.468.510}, and multilevel analysis of complex packing as dimer gives a 18-c uninodal net with unknown topological type and point symbol {348.499.56}. The calculation results of a Hirshfeld surface analysis have been investigated to explore the H-bonding within the crystal. Third-order non-linear properties were also studied, which revealed that the lower input power (5.0 mM) for the material shows full transparency; however, it becomes opaque for higher input power. Such limiting behavior of complex 1 suggests its potential for instrumental protective devices against high laser illuminations. [ABSTRACT FROM AUTHOR]

• Three new Ni(II)/Zn(II)-based complexes synthesized using mixed ligand strategy. • The complexes were characterized using different physico-chemical techniques. • The complexes were used as photocatalyst for photodegradation of methyl violet dye. • The Ni(II) complex displayed best photocatalytic activity for the degradation of MV. Three new complexes comprising Ni(II) and Zn(II) metal centers having compositions [Zn 2 (HL) 2 (bpy) 2 (H 2 O) 2 ] (1), [Ni(H 2 L)(bpy)(H 2 O) 2 (OH)] (2) and [Ni(H 2 L) 2 (bpy) 2 ] (3) have been synthesized by adopting mixed ligand strategy using 4′-(3,4- dicarboxylphenyloxy) -4-biphenylcarboxylic acid (H 3 L) as main ligand and 2,2′-bipyridine (bpy) as co-ligand. These complexes have been characterized by microanalyses, FTIR and single crystal X-ray diffraction technique. The single crystal X-ray analyses reveal that all the three complexes have 2D supramolecular network constructed by hydrogen bonding interactions. These complexes have been employed as photocatalysts for the photodegradation of methyl violet (MV) dye. The photocatalytic experiments reveal that amongst all three complexes, the complex 2 exhibits best photocatalytic performance and degrades 92.8% of MV in time span of 100 min. The plausible photocatalytic degradation mechanism have been proposed with the help of trapping experiments and density of states calculations. Three new Ni(II)/Zn(II)-based complexes with tricarboxylate ligand and bipyridine co-ligand synthesized and used as photocatalyst against methyl violet. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new Zn(II) coordination polymer (CP) synthesized using mixed ligand strategy • The CP was characterized using different physico-chemical techniques • The CP used as luminescent sensor to detect antibiotics • The CP used as photocatalyst for photodegradation of dyes Coordination polymers (CPs) are assorted class of multidimensional materials that could be deployed as sensors and photocatalysts against the photodegradation of aromatic dyes existing in the waste-water discharge. Herein, a new Zn(II)-based coordination polymer (CP) [Zn(dsn)(4,4'-bipy) 0.5 ] (1) has been synthesized by reacting Schiff base ligand 3,5-dibromosalicylaldehyde nicotinoylhydrazone (dsn) and 4,4′-bipyridine (4,4'-bipy) with Zn(NO 3) 2 ·6H 2 O and characterized using elemental analysis, FTIR, TGA, powder X-ray diffraction and single crystal X-ray diffraction techniques. The single crystal X-ray diffraction studies revealed tetragonal pyramidal geometry around Zn(II) and the architecture of 1 is stabilized by π···π interactions operating between pyridine ring of dsn and 4,4'-bipy. Also, other weak non-conventional weak interactions provide stability and engender supramolecular three dimensional framework in 1. The CP has been used as fluorescent sensor to detect antibiotics and exhibits selective sensing of secnidazole (SIZ) with limit of detection (LOD) 8.59 × 10−7 M. This showcase of 1 can act as an efficient and selective sensor for SIZ even in presence of other antibiotics. Also, the CP has been used as photocatalyst for photodegradation of Rhodamine B (Rh B) and degrades 80% of Rh B in 100 min. The plausible mechanism employing which CP 1 executed sensing of secnidazole (SIZ) and photocatalysis of Rh B have been explained with aid of theoretical calculations. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] A new 1D coordination polymer, [Zn(dsn)(HO 2 CCH 3)] n (1), has been synthesized by reacting the Schiff base ligand 3,5-dibromosalicylaldehyde nicotinoylhydrazone (H 2 dsn) with Zn(O 2 CCH 3) 2 ·6H 2 O. The polymer has been characterized using FTIR spectroscopy and single crystal X-ray diffraction analysis. The single crystal X-ray analysis reveals that the immediate geometry around the Zn(II) ion is five-coordinate, that is satisfied by a pyridyl nitrogen atom of one dsn ligand, the imine-N, carbonyl-O and phenoxo-O atoms of the other dsn ligand, as well as the acetate oxygen atom, which generate a trigonal bipyramidal geometry. Furthermore, the dsn ligand coordinated by the pyridyl nitrogen atom also coordinates to another Zn(II) ion by its imine-N, carbonyl-O and phenoxo-O atoms to generate a zig-zag lD polymer chain. The 1D chain is held by weak non-conventional interactions in the solid state to engender a 2D supramolecular layer. The photoluminescent (PL) property of 1 has been investigated and the polymer has been exploited as a sensitive and selective fluorescent sensor to detect metronidazole (MDZ) with limit of detection (LOD) of 9.39 × 10−7 M amongst a variety of related antibiotics. Also, 1 has been used as a photocatalyst and displays excellent photocatalytic degradation of methylene blue (MB), decomposing 86.3% in 100 min under UV light irradiation. The plausible mechanisms which polymer 1 executed for the sensing of MDZ and photodegradation of MB have been explained with the aid of theoretical calculations. [ABSTRACT FROM AUTHOR]

Two new copper(II) and copper(I) complexes were synthesized and tested for their cytotoxic properties. [Display omitted] Herein, two new copper complexes, {[Cu(dmp) 2 (H 2 O)] · (PA) 2 },(1) and {[Cu(dmp) 2 ] · (PA)} , (2) (dmp = 1,10-dimethyl-2,9-phenanthroline, PA = picric acid) have been synthesized solvothermaly and crystal structures were determined by single-crystal X-ray diffraction (SCXRD) technique. Both the complexes 1 and 2 show distorted square planar and distorted tetrahedral geometry around the copper (II) and copper (I) metal centers. In vitro antitumor screening against THP-1 (human leukemia monocytic), PC-3 (human prostate cancer), and SW480 (human colon cancer) cancers indicated their good antiproliferative potential. The morphological assessment data obtained by using dual AO/EB fluorescent staining with THP-1 cell reveal that 1 induces cell death by necrosis, while 2 results in early apoptosis mechanistic pathways. Furthermore, molecular docking of 1′ and 2′ (after removal of picric acid) with DNA of two different conformers were carried out to recognize its preferential binding site either with the minor or major groove of the DNA helix. Together, these results suggest that the copper complexes bearing different oxidation states mediated cell death operates combined mechanism encompassing apoptosis and necrosis possibly due to the DNA damage. The present studies suggest that the picric acid derived copper complexes could be an attractive chemotherapeutic agents against cytotoxic cells. [ABSTRACT FROM AUTHOR]