Novel Molecular Building Blocks Based on the Boradiazaindacene Chromophore: Applications in Fluorescent Metallosupramolecular Coordination Polymers

Bright polymers : Fluorescent coordination polymers made up of versatile functionalized bodipy (boron‐dipyrrin) chromophore building blocks, such as that depicted, are described. Polymerization is signaled by changes in fluorescence emission intensity and shifts in peak emission wavelengths.

     

T X is absolutely closed

If S, T are semigroups with S⊂T, then the dominion of S in T, Dom(S,T), is the set of all x ε T such that for each semigroup U and for each pair of homomorphisms f,g: T→U with f|S=g|S, then f(x)=g(x). S is absolutely closed if Dom(S,T)=S for all T. That full transformation semigroups are absolutely closed has previously been reported. The intent here is to offer a corrected proof of that theorem.     

Neuroactive Peptide Nanofibers for Regeneration of Spinal Cord after Injury

The highly complex nature of spinal cord injuries (SCIs) requires design of novel biomaterials that can stimulate cellular regeneration and functional recovery. Promising SCI treatments use biomaterial scaffolds, which provide bioactive cues to the cells in order to trigger neural regeneration in the spinal cord. In this work, the use of peptide nanofibers is demonstrated, presenting protein binding and cellular adhesion epitopes in a rat model of SCI. The self‐assembling peptide molecules are designed to form nanofibers, which display heparan sulfate mimetic and laminin mimetic epitopes to the cells in the spinal cord. These neuroactive nanofibers are found to support adhesion and viability of dorsal root ganglion neurons as well as neurite outgrowth in vitro and enhance tissue integrity after 6 weeks of injury in vivo. Treatment with the peptide nanofiber scaffolds also show significant behavioral improvement. These results demonstrate that it is possible to facilitate regeneration especially in the white matter of the spinal cord, which is usually damaged during the accidents using bioactive 3D nanostructures displaying high densities of laminin and heparan sulfate‐mimetic epitopes on their surfaces.     

Dipolar Photosystems: Engineering Oriented Push–Pull Components into Double‐ and Triple‐Channel Surface Architectures

Push–pull aromatics are not popular as optoelectronic materials because their supramolecular organization is difficult to control. However, recent progress with synthetic methods has suggested that the directional integration of push–pull components into multicomponent photosystems should become possible. In this study, we report the design, synthesis, and evaluation of double‐ or triple‐channel architectures that contain π stacks with push–pull components in parallel or mixed orientation. Moreover, the parallel push–pull stacks were uniformly oriented with regard to co‐axial stacks, either with inward or outward oriented push–pull dipoles. Hole‐transporting (p) aminoperylenemonoimides (APIs) and aminonaphthalimides (ANIs) are explored for ordered push–pull stacks. For the co‐axial electron‐transporting (n) stacks, naphthalenediimides (NDIs) are used. In double‐channel photosystems, mixed push–pull stacks are overall less active than parallel push–pull stacks. The orientation of the parallel push–pull stacks with regard to the co‐axial NDI stacks has little influence on activity. In triple‐channel photosystems, outward‐directed dipoles in bridging stacks between peripheral p and central n channels show higher activity than inward‐directed dipolar stacks. Higher activities in response to direct irradiation of outward‐directed parallel stacks reveal the occurrence of quite remarkable optical gating.     

Bidirectional switching of near IR emitting boradiazaindacene fluorophores

Two novel distyryl-boradiazaindacene dyes with dimethylaminostyryl and pyridylethenyl substituents display opposite spectral shifts on protonation with TFA in organic solvents. This bidirectional switching of the dyes can be shown to be directly related to ICT donor and acceptor characteristics of the substituents attached to the BODIPY core. The observed spectral response of these dyes could be very useful in the design of novel NIR fluorescent ratiometric probes for pH.     

Highly Chemoselective Thiocarbonyl Oxidation upon Reaction of 4-Methyl-3-phenyl-2-thiazolidinethione with Singlet Oxygen

4-Methyl-3-phenyl-2-thiazolidinethione was reacted with both photochemically and chemically generated singlet oxygen. Despite reaction conditions which were selected to favor oxidation of the sulfide group, both reactions afforded a single product arising solely from thiocarbonyl oxidation.