We show that adding chlorine atoms to conjugated cores is a general, effective route toward the design of n-type air-stable organic semiconductors. We find this to be true for acenes, phthalocyanines, and perylene tetracarboxylic diimide (PDI)-based molecules. This general finding opens new avenues in the design and synthesis of organic semiconductors. We compared a series of fluoro- and chloro-functionalized acenes, phthalocyanines, and PDI-based molecules. The acenes synthesized showed high and balanced ambipolar transport in the top-contact organic field effect transistor (OFET) geometry. The electron-withdrawing halogen groups lowered the LUMO and the charge injection barrier for electrons, such that electron and hole transport occurred simultaneously. If the chlorine added does not distort the planarity of the conjugated core, we found that the chloro-functionalized molecules tend to have a slightly smaller HOMO-LUMO gap and a lower LUMO level than the fluoro-containing molecules, both from calculations and cyclic voltammetry measurements in solution. This is most likely due to the fact that Cl contains empty 3d orbitals that can accept pi-electrons from the conjugated core, while F does not have energetically accessible empty orbitals for such delocalization.

We investigate the relationship between the charge carrier type in organic thin film transistors (OTFTs) and molecular energy levels. We examine a series of functionalized acenes that collectively have their HOMOs range from -4.9 eV to -5.6 eV and LUMOs range from -2.8 eV to -3.7 eV, as measured by cyclic voltammetry. Placed together, these 20 molecules allow us to chart the transition from OTFTs that display only hole transport, to ambipolar, to solely electron transport. Specifically, we note that for octadecyltrimethoxysilane (OTS) treated substrates, with top contact gold electrodes, electron injection and transport occurs when the LUMO < -3.15 eV, while hole injection and transport ceases when the HOMO < -5.6 eV. Ambipolar transport prevails when molecules have HOMO/ LUMO levels within the aforementioned range. This is seen across channel lengths ranging from 50-150 microm and using only gold as electrodes. This empirical plot is the first time such a detailed study has been made on the onset of charge injection and transport for a class of organic semiconductors. It provides guidelines for future molecular design.

Nuclear-factor κB (NF-κB) transcription factors are activated by a wide variety of stimuli in diverse cell types and control key aspects of immune function and development. Receptor-mediated activation of NF-κB appears to occur through two distinct signaling pathways termed as the canonical and non-canonical NF-κB pathways. Although much work has demonstrated the physiological importance of non-canonical NF-κB signaling to immunity and its involvement in diverse pathologies, such as cancers and autoimmune disease, the architecture and regulation of the pathway is only beginning to be understood. The non-canonical pathway appears to be activated by a select set of receptors within the tumor necrosis factor superfamily, and we discuss the molecular mechanisms that connect ligation of these receptors to pathway activation. It has become increasingly clear that the key regulatory step of the pathway involves modulation of the post-translational degradation of NF-κB-inducing kinase (NIK), the central activating kinase of non-canonical NF-κB signaling. How NIK post-translational stability is controlled before and after receptor ligation is an important aspect of understanding non-canonical NF-κB signaling. Furthermore, how release of NF-κB dimers downstream of the pathway's activation is actually connected to its identified physiological and pathological roles is a key remaining question in the field.

We present a high performance, ambipolar organic field-effect transistor composed of a single material. Ambipolar molecules are rare, and they can enable low-power complementary-like circuits. This low band gap, asymmetric linear acene contains electron-withdrawing fluorine atoms, which lower the molecular orbital energies, allowing the injection of electrons. While hole and electron mobilities of up to 0.071 and 0.37 cm2/V.s, respectively, are reported on devices measured in nitrogen, hole mobilities of up to 0.12 cm2/V.s were found in ambient, with electron transport quenched. These devices were fabricated on octadecyltrimethoxysilane-treated surfaces at a substrate temperature of 60 degrees C.