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Colloidal particles based on supramolecular polymers are emerging as promising functional materials because of their intrinsic dynamic features and the possibility of stimuli responsivity. In this work, ≈200 nm self-assembled redox-responsive colloidal particles made of 1D-coordination polymers were readily prepared. In these metallopolymers, organic entities made of bis(viologen) groups covalently associated with terpyridine units are spontaneously bridged by Zn 2+ cations through the formation of coordination bonds. The properties of these particles were analyzed and their redox activities investigated. Upon reduction of the viologen units, the formation of π-dimers between the reduced viologen moieties was demonstrated by spectroscopic experiments. It was shown that intermolecular π-dimers (i.e., between different polymer chains) that do not exist in homogeneous polymer solutions were, nevertheless, formed in the particle's structure because of the effects of confinement. The presence of these π-dimers allows stabilization of the charge in the colloids.

We report the study of stimuli-responsive Zn II and Fe II coordination polymers (MC3 4+ or MC2 4+ with M=Fe 2+ or Zn 2+ ). These soluble metallopolymers were formed spontaneously by reaction of an organic ligand (C3 4+ or C2 4+ ) with one molar equivalent of metal ions. The C3 4+ and C2 4+ ligands incorporate two chelating terpyridine groups bridged by a redox responsive hinge featuring two viologen units (viologen=N,N'-dialkyl-4,4'-bipyridinium) linked either with propyl (C3 4+ ) or ethyl (C2 4+ ) chains. The viologen units in the polymer chains were reduced (1 e - per viologen group) either by bulk electrolysis or by visible-light irradiation carried out in the presence of a photosensitizer. The 1 e - reduction of the viologen units in the MC2 4+ polymers induced a slight decrease in the viscosity of the solutions due to a modification of the overall charge carried by the metallopolymers. In strong contrast, reduction of coordination polymers involving propyl linkers (MC3 4+ ) led to a remarkable increase (≈+400 %) in observed viscosity. This reversible effect was attributed to a folding of the polymer chains triggered by π-dimerization of the photo-generated viologen cation radicals., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This work reports on the synthesis and characterization of a new porphyrins complex:[Zn(TEBOP)(4,4'-bpy)](4,4'-bipyridine)(5,10,15,20-(tetraethyl-4(4-butyryl)oxyphenyl)porphyrinato)zinc(ii) (3). Single crystal X-ray diffraction, photophysical and electrochemical characteristics were studied. The prepared complex, penta-coordinated zinc(ii) porphyrin derivatives shows moderate ruffling distortion and the zinc atom is nearly planar with the porphyrin core. Tolyl and ethyl-4(4-butyryl)oxyphenyl) moieties at the meso positions present a bathochromic shift of the absorption bands, and a notable increase in the absorption coefficient of the Q(0,0) and Q(0,1) bands was observed with a higher fluorescence quantum yield and lifetime compared with the free base porphyrin. The electrochemical investigation shows a reversible reduction of the synthesized complexes. The catalytic power and the adsorption properties of the prepared complexes were studied for Calmagite degradation, an azoic organic dye. The results reveal that the studied compounds could be used as catalysts for the decolourisation of dyes in the presence of H 2 O 2 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)