Aromaticity and Antiaromaticity in the Excited States of Porphyrin Nanorings

American Chemical Society (ACS) (0)

M Peeks, J Gong, K McLoughlin, T Kobatake, R Haver, L Herz, HL Anderson

<jats:p>Aromaticity can be a useful concept for predicting the behavior of excited states. Here we show that π-conjugated porphyrin nanorings exhibit size-dependent excited-state global aromaticity and antiaromaticity, for rings containing up to eight porphyrin subunits, although they have no significant global aromaticity in their neutral singlet ground states. Applying Baird’s law, odd rings ([4n] π-electrons) are aromatic in their excited states, whereas the excited states of even rings ([4n+2] π-electrons) are antiaromatic. These predictions are borne out by density functional theory (DFT) studies of the nucleus-independent chemical shift in the T1 triplet state of each ring, which reveal the critical importance of the triplet delocalization to the emergence of excited-state aromaticity. The singlet excited states (S1) are explored by measurements of the radiative rate and fluorescence peak wavelength, revealing a subtle odd-even alternation as a function of ring size, consistent with symmetry-breaking in antiaromatic excited states.</jats:p>

Dual-Source Coevaporation of Low-Bandgap FA1–xCsxSn1–yPbyI3 Perovskites for Photovoltaics

ACS Energy Letters American Chemical Society (ACS) (0) 2748-2756

JM Ball, L Buizza, HC Sansom, MD Farrar, MT Klug, J Borchert, J Patel, LM Herz, MB Johnston, HJ Snaith

Barrier engineering of a photonic molecule in a photonic crystal waveguide

Conference on Lasers and Electro-Optics 2016 (0)

RA Taylor, FSB Brossard, B Reid, L Nuttall, S Lennon, R Murray

Investigation of Intense Luminescence from Chemically-Etched Silicon Nanowires

27th European Photovoltaic Solar Energy Conference and Exhibition (0)

RA Taylor, M Hadjipanayi, F Voigt, V Sivakov, X Wang, S Christiansen, GE Georghiou

Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells

Nature Communications Nature Publishing Group: Nature Communications (0)

A Haghighirad

Pressure-Transferred components

(0) 503450223

MG Christoforo, MD McGehee, A Salleo, CD Bailie

Wobbe Index Sensor System

(0) 11/777,575

AJ Knobloch, WJ Antel, JR, MG Christoforo, RM Orenstein

A sensor for measuring Wobbe index of a fuel is provided. The sensor includes a substrate and a diaphragm layer. The diaphragm layer includes a first layer having at least one heating element configured to sense energy content in a fuel, wherein the heating element includes a doped poly-silicon carbide that is disposed on the substrate. The diaphragm layer also includes a second layer including an undoped poly-silicon carbide layer configured to prevent oxidation of the first layer. The sensor further includes a sensing layer having a catalyst suspended in a support structure. The sensor also includes a cavity formed under the diaphragm layer and is configured to provide thermal isolation of the heating element.