Low band‐gap diketopyrrolopyrrole‐containing polymers for near infrared electrochromic and photovoltaic applications

Donor–acceptor type polymers bearing diketopyrrolopyrrole and 3,4‐ethylenedioxythiophene units are reported. The polymers are green and exhibit very low band‐gaps (1.19 eV) with strong and broad absorption (maxima of about 830 nm) in the near infrared (NIR) region in their neutral film states. The polymers display color changes between dark green and light blue with exceptional optical contrasts in the NIR regions of up to 78 and 63% as thin films and single‐layer electrochromic devices, respectively. Fast switching, good stabilities as well as high coloration efficiencies (743–901 cm² C^?1) were also observed. The polymers could also be potentially used as photovoltaic material, with a power conversion efficiency of up to 1.68%. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1287–1295     

Peptoid‐Ligated Pentadecanuclear Yttrium and Dysprosium Hydroxy Clusters

A new family of pentadecanuclear coordination cluster compounds (from now on simply referred to as clusters) [{Ln₁₅(OH)₂₀(PepCO₂)₁₀(DBM)₁₀Cl}Cl₄] (PepCO₂=2‐[{3‐(((tert‐butoxycarbonyl)amino)methyl)benzyl}amino]acetate, DBM=dibenzoylmethanide) with Ln=Y and Dy was obtained by using the cell‐penetrating peptoid (CPPo) monomer PepCO₂H and dibenzoylmethane (DBMH) as supporting ligands. The combination of an inorganic cluster core with an organic cell‐penetrating peptoid in the coordination sphere resulted in a core component {Ln₁₅(μ₃‐OH)₂₀Cl}²⁴⁺ (Ln=Y, Dy), which consists of five vertex‐sharing heterocubane {Ln₄(μ₃‐OH)₄}⁸⁺ units that assemble to give a pentagonal cyclic structure with one Cl atom located in the middle of the pentagon. The solid‐state structures of both clusters were established by single‐crystal X‐ray crystallography. MS (ESI) experiments suggest that the cluster core is robust and maintained in solution. Pulsed gradient spin echo (PGSE) NMR diffusion measurements were carried out on the diamagnetic yttrium compound and confirmed the stability of the cluster in its dicationic form [{Y₁₅(μ₃‐OH)₂₀(PepCO₂)₁₀(DBM)₁₀Cl}Cl₂]²⁺. The investigation of both static (dc) and dynamic (ac) magnetic properties in the dysprosium cluster revealed a slow relaxation of magnetization, indicative of single‐molecule magnet (SMM) behavior below 8 K. Furthermore, the χT product as a function of temperature for the dysprosium cluster gave evidence that this is a ferromagnetically coupled compound below 11 K.     

Single-slit diffraction of the arbitrary vector beams

We present the single-slit diffraction of the arbitrary vector fields with different parameters m, n, and φ0theoretically and experimentally. The single slit covers the polarization singularity in the center and therefore the influence of the polarization singularity on the diffraction fringes is analyzed. The experimental results which agree well with the simulation results show that the total intensity of the diffraction field is related only to the topological charge m, but the polarization distribution of the diffraction field is related to all the parameters m, n, and φ0. Therefore, the diffraction patterns allow to determine all the parameters of the arbitrary vector fields.     

Small molecule‐mediated glass transition of acrylic copolymers: Effect of hydrogen bonding strength on glass transition temperature

Poly(styrene‐co‐ethyl acrylate) [P(St‐co‐EA)] with different ratios of St/EA was mixed with the small molecule 4,4′‐thio‐bis(6‐tert‐butyl‐m‐methyl phenol) (AO300) to investigate the influence of hydrogen bonding strength on the glass transition behavior. The glass transition temperature (T_g) linearly increased after adding AO300, and the slope value decreased with increased St/EA ratio. All lines could be extended to 62 °C, demonstrating that T_g of the small molecule in situ detected by the polymer chain was much higher than that by small molecule itself (29 °C). Fourier transform infrared spectroscopy analysis showed that the small molecules began to be self‐associated at a concentration where the hydrogen bonded carbonyl ratio of the bulk polymer was approximately 0.5 and irrespective of the St/EA ratio. Above the critical loading, the mixture's T_g negatively deviated from the linearly extended lines because of self‐association of the small molecules. The apparent T_g of AO300 was found to strongly depend on intermolecular hydrogen bonding number and strength. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 400–408