A Cd(ii)-based coordination compound, [CdI2(4-nvp)2] (1), has been synthesized using CdI2 and monodentate N-donor ligand 4-(1-naphthylvinyl)pyridine (4-nvp).

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Two newly designed coordination polymers (CPs), [Zn(adc)(4-Cltpy)(H2O)] (CP1) and [Zn(trans-muca)(4-Cltpy)] (CP2) (4-Cltpy = 4′-Chloro-2,2′:6′,2′′-terpyridine, H2adc = Acetylene- dicarboxylic acid, trans-H2muca = trans, trans-muconic acid) are synthesized and structurally characterized by...

Photoluminescence activity of coordination polymers (CPs) has evoked intricate applications in the field of materials science, especially sensing of ions/molecules. In the present study, 2,3,5,6-tetrakis­(2-pyridyl)­pyrazine (tppz) and 5-aminoisophthalate (HAIPA–) coordinated to Cd­(II) to architect a coordination polymer, {[Cd­(HAIPA)­(tppz)­(OH)]·3H2O} n (CP1) which unveils blue emission in an aqueous acetonitrile (98% aqueous) suspension. The emission is selectively quenched by Pd2+ only without interference in the presence of as many as 16 other cations. The structure of CP1 shows the presence of a free –COOH group, and the interlayer (–CO)­O(2)···O(7) (OC–) distance, 4.242 Å, along with the π···π interactions (3.990, 3.927 Å), may make a cavity which suitably accommodates only Pd2+ (van der Waal’s radius, 1.7 Å) through the Pd­(II)-carboxylato (–COO–Pd) coordination. The stability of the composite, [CP1 + Pd2+] may be assessed from the fluorescence quenching experiment, and the Stern–Volmer constant (K SV) is 7.2 × 104 M–1. Therefore, the compound, CP1, is a promising sensor for Pd­(II) in a selective manner with limit of detection (LOD), 0.08 μM. The XPS spectra of CP1 and [CP1 + Pd2+] have proven the presence of Pd2+ in the host and the existence of a coordinated –COO–Pd bond. Interestingly, inclusion of Pd2+ in CP1 decreases the band gap from 3.61 eV (CP1) to 3.05 eV ([CP1 + Pd2+]) which lies in the semiconducting region and has exhibited improved electrical conductivity from 7.42 × 10–5 (CP1) to 1.20 × 10–4 S m–1 ([CP1 + Pd2+]). Upon light irradiation, the electrical conductivities are enhanced to 1.45 × 10–4 S m–1 (CP1) and 3.81 × 10–4 S m–1 ([CP1 + Pd2+]); which validates the highly desired photoresponsive device applications. Therefore, such type of materials may serve as SDG-army (sustainable development goal) to battle against the environmental issues and energy crisis.

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+.