One-Dimensional Anhydrous Proton Conducting Channel Formation at High Temperature in a Pt(II)-Based Metallo-Supramolecular Polymer and Imidazole System

One dimensional (1D) Pt­(II)-based metallo-supramolecular polymer with carboxylic acids (polyPtC) was synthesized using a new asymmetrical ditopic ligand with a pyridine moiety bearing two carboxylic acids. The carboxylic acids in the polymer successfully served as apohosts for imidazole loaded in the polymer interlayer scaffold to generate highly ordered 1D imidazole channels through the metallo-supramolecular polymer chains. The 1D structure of imidazole loaded polymer (polyPtC-Im) was analyzed in detail by thermogravimetric analysis, powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and ultraviolet–visible and photoluminescence spectroscopic measurements. PolyPtC-Im exhibited proton conductivity of 1.5 × 10^–5 S cm^–1 at 120 °C under completely anhydrous conditions, which is 6 orders of magnitude higher than that of the pristine metallo-supramolecular polymer

Platinum(II)-Based Metallo-Supramolecular Polymer with Controlled Unidirectional Dipoles for Tunable Rectification

A platinum­(II)-based, luminescent, metallo-supramolecular polymer (PolyPtL1) having an inherent dipole moment was synthesized via complexation of Pt­(II) ions with an asymmetric ligand L1, containing terpyridyl and pyridyl moieties. The synthesized ligand and polymer were well characterized by various NMR techniques, optical spectroscopy, and cyclic voltammetry studies. The morphological study by atomic force microscopy revealed the individual and assembled polymer chains of 1–4 nm height. The polymer was specifically attached on Au-electrodes to produce two types of film (films 1 and 2) in which the polymer chains were aligned with their dipoles in opposite directions. The Au-surface bounded films were characterized by UV–vis, Raman spectroscopy, cyclic voltammetry, and atomic force microscopy study. The quantum mechanical calculation determined the average dipole moment for each monomer unit in PolyPtL1 to be about 5.8 D. The precise surface derivatization permitted effective tuning of the direction dipole moment, as well as the direction of rectification of the resulting polymer-attached molecular diodes. Film 1 was more conductive in positive bias region with an average rectification ratio (RR = <i>I</i>(+4 V)/<i>I</i>(−4 V)) ≈ 20, whereas film 2 was more conducting in negative bias with an average rectification ratio (RR = <i>I</i>(−4 V)/<i>I</i>(+4 V)) ≈ 18

Selective DNA Recognition and Cytotoxicity of Water-Soluble Helical Metallosupramolecular Polymers

Water-soluble helical Fe­(II)-based metallosupramolecular polymers ((<i>P</i>)<b>-</b> and (<i>M</i>)-polyFe) were synthesized by 1:1 complexation of Fe­(II) ions and bis­(terpyridine)­s bearing a (<i>R</i>)- and (<i>S</i>)-BINOL spacer, respectively. The binding affinity to calf thymus DNA (ct-DNA) was investigated by titration measurements. (<i>P</i>)-PolyFe with the same helicity as B-DNA showed 40-fold higher binding activity (<i>K</i>_b = 13.08 × 10⁷ M^–1) to ct-DNA than (<i>M</i>)-polyFe. The differences in binding affinity were supported by electrochemical impedance spectroscopy analysis. The charge-transfer resistance (<i>R</i>_ct) of (<i>P</i>)-polyFe increased from 2.5 to 3.9 kΩ upon DNA binding, while that of (<i>M</i>)-polyFe was nearly unchanged. These results indicate that ionically strong binding of (<i>P</i>)-polyFe to DNA chains decreased the mobility of ions in the conjugate. Unique rod-like images were obtained by atomic force microscopy measurement of the DNA conjugate with (<i>P</i>)-polyFe, likely because of the rigid binding between DNA chains and the polymer. Differences in polymer chirality lead to significantly different cytotoxicity levels in A549 cells. (<i>P</i>)-PolyFe showed higher binding affinity to B-DNA and much higher cytotoxicity than (<i>M</i>)-polyFe. The helicity in metallosupramolecular polymer chains was important not only for chiral recognition of DNA but also for coordination to a biological target in the cellular environment