Spectrophotometric Determination of Trace Amount of Total FeII/FeIII and Live Cell Imaging of a Carboxylato Zn(II) Coordination Polymer.

The coordination polymer, (Zn(II)-CP, 1), {[Zn(2,6-NDC)(4-Cltpy)](H2O)4} (1) (2,6-H2NDC = 2,6-naphthalene dicarboxylic acid and 4-Cltpy = 4'-chloro-[2,2';6',2″]terpyridine) is structurally characterized by single crystal X-ray diffraction measurement and other physicochemical studies (PXRD, FTIR, thermal analysis, microanalytical data). 4-Cltpy acts as end-capping ligand, and NDC2- is a carboxylato bridging motif to constitute ZnN3O2 distorted trigonal bipyramid core that propagates to construct 1D chain. The coordination polymer, 1, detects total iron (Fe3+ and Fe2+) in aqueous solution by visual color change, colorless to pink. Absorption spectrophotometric technique in aqueous medium measures the limit of detection (LOD) 0.11 µM (Fe2+) and 0.15 µM (Fe3+), and binding constants (Kd) are 6.7 × 104 M-1 (Fe3+) and 3.33 × 104 M-1 (Fe2+). Biocompatibility of 1 is examined in live cells, and intracellular Fe2+ and Fe3+ are detected in MDA-MB 231 cells. Zn(II) substitution is assumed upon addition of FeIII/FeII solution to the suspension of the coordination polymer, 1, in water-acetonitrile (41:1) (LZnII + FeIII/II → LFeIII + ZnII, where L is defined as coordinated ligands), which is accompanied by changing from colorless to pink at room temperature. The color of the mixture may be assumed to the charge transfer transition from carboxylate-O to Cltpy via Fe(II/III) bridging center (carboxylate-O-Fe-CltPy). The product isolated from the reaction is finally characterized as Fe(III)@1-CP. It is presumed that product Fe(II)@1-CP may undergo fast aerial oxidation to transform Fe(III)@1-CP. The FeIII exchanged framework (Fe(III)@1-CP) has been characterized by PXRD, IR, TGA and energy dispersive X-ray analysis (EDX)-SEM. The MTT assay calculates the cell viability (%), and the tolerance limit is 100 µM to total Fe2+ and Fe3+.

A Reusable Efficient Green Catalyst of 2D Cu-MOF for the Click and Knoevenagel Reaction.

[Cu(CPA)(BDC)]n (CPA = 4-(Chloro-phenyl)-pyridin-4-ylmethylene-amine; BDC = 1,4-benzenedicarboxylate) has been synthesized and structurally characterized by single crystal X-Ray diffraction measurement. The structural studies establish the copper (II) containing 2D sheet with (4,4) square grid structure. The square grid lengths are 10.775 and 10.769 Å. Thermal stability is assessed by TGA, and subsequent PXRD data establish the crystallinity. The surface morphology is evaluated by FE-SEM. The N2 adsorption-desorption analysis demonstrates the mesoporous feature (∼6.95 nm) of the Cu-MOF. This porous grid serves as heterogeneous green catalyst with superficial recyclability and thermal stability and facilitates organic transformations efficiently such as, Click and Knoevenagel reactions in the aqueous methanolic medium.

Coordination polymers of Ag(i) and Hg(i) ions with 2,2'-azobispyridine: synthesis, characterization and enhancement of conductivity in the presence of Cu(ii) ions.

The cationic coordination polymers (CPs) of the types [Hg2(abpy)2]n[PF6]2n (1) and [Ag(abpy)]n[PF6]n (2) (abpy = 2,2'-azobispyridine) were synthesized and characterized. Experimentation using the crystals confirmed that 1 and 2 are conductors of electricity. The relative conductivity of 1 is 62 times greater than that of 2. The conductivity of 1 increases 70 fold when it reacts with Cu2+ ions.

Biporous Cd(II) Coordination Polymer via in Situ Disulfide Bond Formation: Self-Healing and Application to Photosensitive Optoelectronic Device.

A heteroporous metal-organic framework, [Cd2(2,2'-DSB)2(INH)2(H2O)2]n (1), is fabricated by the reaction of CdI2, 2-mercaptobenzoic acid (2-MBAH), and isoniazid (INH). The X-ray structure of the compound 1 shows the bridging INH and 2,2'-disulfanediyldibenzoic acid (H22,2'-DSBA) around the Cd(II) ion center. 2-MBAH has been in situ dimerized to the formation of 2,2'-DSB2- (S-S-bonded dianion), which has further extended to form the 2D network. However, supramolecular assembly via π···π and hydrogen bonds strengthens the structural motif within the 3D array. Optical stimulation generated the thiol radical under an argon environment followed by the electron paramagnetic resonance (EPR) study, but upon exposure to air, the EPR signal gradually disappeared by the formation of the S-S bond, which was commonly known as a self-healing property. Again, compound 1 exhibited as a semiconducting material with a band gap of 3.7 eV. The I-V characteristics of 1 show that the conductivity is intensified by an optical response. The Schottky diode property of 1 shows a lower barrier height, a lower resistance, and a higher conductivity upon illumination at 360 nm.

Designing of Pb(II)-Based Novel Coordination Polymers (CPs): Structural Elucidation and Optoelectronic Application.

[Pb2(bdc)1.5(aiz)] n (1) and [Pb2(bdc)1.5(aiz)(MeOH)2] n (2) (H2bdc = 1,4-benzene dicarboxylic acid, aiz = (E)-N'-(thiophen-2-ylmethylene)isonicotinohydrazide) have been synthesized, and structural characterization has been established by X-ray analysis and thermogravimetric analysis (TGA). Here, bdc2- links two Pb(II) centers and the aiz ligand binds the metal centers in two different manners: chelating and monodonating. Thus, polymerizations have taken place from the combination of mixed ligand system. Optical band gaps have been studied via UV measurements. Again, the experimental and calculated (from density functional theory (DFT)) band gaps agree well and the semiconducting properties of synthesized polymeric materials have been approved. Thus, optoelectronic and photonic devices can be made by this type of coordination polymers (CPs). The I-V representative curves of 1 (device-A) and 2 (device-B) in both dark and illuminated conditions show that device-A has a higher magnitude of current than device-B. Dark- and photo-conductivity values of device-A are calculated as 2.94 × 10-6 and 6.12 × 10-6 S m-1, respectively, whereas for device-B, the values of dark- and photo-conductivity are 2.92 × 10-7 and 3.66 × 10-7 S m-1, respectively, at room temperature.

Specific recognition of Cr3+ under physiological conditions by allyl substituted appendage rhodamine and its cell-imaging studies.

An allyloxynitrophenylimio-propylhydroxyl appended rhodamine (RD-3) specifically recognises Cr3+ in aqueous buffer medium at pH 7.4. The visible light excitable reagent (λex 505 nm) on selective binding to Cr3+ exhibited a strong fluorescence turn-on response with powerful emission at 557 nm and the tail of this luminescence band is extended to ∼650 nm. Interference studies confirm that other metal ions (27 ions) do not hamper the detection process of Cr3+. The sensing mechanism is studied by absorption, fluorescence, Job's plot, and 1H NMR titration studies. The detection limit is as low as 33 nM. The practical applicability of RD-3 is examined for imaging Cr(iii) ions in HCT116 (human colorectal carcinoma) cells.