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The title compound, [Cu 2 (C 19 H 23 N 7 O)(C 2 H 3 O 2 ) 4 ] n , was obtained via reaction of copper(II) acetate with the coordinating ligand, 6-ethoxy- N 2 , N 4 -bis[2-(pyridin-2-yl)ethyl]-1,3,5-triazine-2,4-diamine. The crystallized product adopts the monoclinic P 2 1 / c space group. The metal core exhibits a paddle-wheel structure typical for dicopper tetraacetate units, with triazine and pyridyl nitrogen atoms from different ligands coordinating to the two axial positions of the paddle wheel in an asymmetric manner. This forms a coordination polymer with the segments of the polymer created by the c -glide of the P 2 1 / c setting of the space group. The resulting chains running along the c -axis direction are held together by intramolecular N—H...O hydrogen bonding. These chains are further packed by dispersion forces, producing an extended three-dimensional structure. 

The study evaluates compatibility of stabilizers with dye doped liquid crystal (LC) scaffolds that are used in electronically dimmable materials. The photodegradation of the materials was investigated and suitable stabilizers were evaluated to slow the degradation process. Various types of benzotriazole-based stabilizers were evaluated for stabilizing the liquid crystals. Based on spin trapping experiments, radicals generated upon UV exposure is likely responsible for the degradation of the system. The radical generation is competitively inhibited by the addition of stabilizers. 

With the aim to construct a new type of photoswitchable photochromic material modulated by specific radiation in the microwave region, the spin dynamics of radical pairs (RPs) from ion-pair complexes between viologen and tetraarylborate compounds have been investigated in the presence of microwave (μw) radiation, using steady-state electron paramagnetic resonance (SSEPR) to follow the radical pair (RP) dynamics. This strategy is realized by excitation of the charge transfer (CT) absorption band of the ion-pair complex in the solid phase (powders and dispersed in polymer matrices) at 410 nm, which leads to electron transfer from borate to viologen, producing RPs. In the singlet excited state or Partially Separated Charge (PSC) state, an electron transfer process occurs between the ions, and the subsequent (purple) viologen radical is observed as a Fully Charge Separated (FCS) state. In solid state SSEPR experiments, μw radiation deactivates the FSC state by inducing back electron transfer, which subsequently increases the population of a Partially Separated Charge (PSC) state, recovering the initial color of the ion-pair complex. State-of-the-art photophysical and photochemical studies show that deactivation of the FSC state can take place using μw radiation on the RPs in a switchable, reversible fashion. The results have potential impact for a number of applications including photo-writing and photo-erasing processes and spintronics. Examples of laser writing using a polymer matrix to lock the relative positions of the radicals, and then erasing the color using microwaves, are presented and discussed.