Hemithioindigos for Cellular Photopharmacology: Desymmetrised Molecular Switch Scaffolds Enabling Design Control over the Isomer-Dependency of Potent Antimitotic Bioactivity

Druglike small molecules with photoswitchable bioactivity—photopharmaceuticals—allow biologists to perform studies with exquisitely precise and reversible, spatial and temporal control over critical biological systems inaccessible to genetic manipulation. The photoresponsive pharmacophores disclosed have been almost exclusively azobenzenes, which has limited the structural and substituent scope of photopharmacology. More detrimentally, for azobenzene reagents, it is not researchers’ needs for adapted experimental tools, but rather protein binding site sterics, that typically force whether the trans (dark) or cis (lit) isomer is the more bioactive. We now present the rational design of HOTubs, the first hemithioindigo-based pharmacophores enabling photoswitchable control over endogenous biological activity in cellulo. HOTubs optically control microtubule depolymerisation and cell death in unmodified mammalian cells. Notably, we show how the asymmetry of hemithioindigos allows a priori design of either Z- or E- (dark- or lit)-toxic antimitotics, whereas the corresponding azobenzenes are exclusively lit-toxic. We thus demonstrate that hemithioindigos enable an important expansion of the substituent and design scope of photopharmacological interventions for biological systems.     

CuInSe2 cells and modules

Recent CuInSe₂ photovoltaic technology advances are discussed. 14.1% active area efficient test cells and the fabrication of monolithic integrated modules with power outputs of 112 W/m² on 940 cm² and 91.4 W/m² on 3900 cm² have been achieved. Packaged modules are stable outdoors. Studies indicate a recombination controlled junction mechanism and imply a wide CIS compositional range over which high-efficiency junctions are possible. Processing improvements already demonstrated on test cells and 940 cm² modules will yield 52-W, 3900-cm² CIS modules     

Low‐Voltage Electro‐Optic Modulation Using Amorphous Polycarbonate Host Material

The selection process leading to the development of a guest–host electro‐optic material based on an amorphous polycarbonate (APC) is described. The optical loss at 1300 nm of this material system is under 2 dB/cm, which is the confidence limit of the slab measurement used. A Mach–Zehnder modulator fabricated using the push–pull poling technique has a low switching voltage (V_π) of 1.2 V.     

Steric Modulation of the Porphycene System by Alkyl Substituents: 9,10,19,20-Tetraalkylporphycenes

Porphycene ( 2 ), a planar structural isomer of porphyrin ( 1 ) recognized and synthesized only recently, exhibits short N … N distances allowing exceptionally strong N-H … N hydrogen bonds to be formed. Although the N₄-coordination hole of 2 is smaller than that of 1 , the new tetrapyrrolic macrocycle is capable of complexation with a broad spectrum of metal ions to give the respective metalloporphycenes. In accord with model considerations, both N-H … N hydrogen bonding and complexation of 2 may be modulated by peripheral alkyl groups through changes in the geometry of the porphycene skeleton arising from non-bonded repulsions between the substituents. In this publication are delineated some of the consequences of structural variation of 2 by introduction of alkyl groups at the 9,10,19,20-positions.