27) Clusters. -Size-selected protonated water clusters H + (H 2 O) n (n = 6-27) are characterized by IR spectroscopy of OH stretches in the gas phase. Spectral features disappearing for the n = 21 magic cluster indicate that all the dangling OH groups arise from water molecules in similar binding sites. It is suggested that the n = 21 cluster structure consists of a dodecahedral cage with a single interior water molecule. -(SHIN, J.-W.; HAMMER, N. I.; DIKEN, E. G.; JOHNSON*, M. A.; WALTERS, R. S.; JAEGER, T.

No abstract

No abstract

No abstract

Poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a popular hole transport material in perovskite solar cells (PSCs). However, the devices with PEDOT:PSS exhibit large open‐circuit voltage (Voc) loss and low efficiency, which is attributed to mismatched energy level alignment and the poor interface of PEDOT:PSS and perovskite. Here, three polymer analogues to polyaniline (PANI), PANI–carbazole (P1), PANI–phenoxazine (P2), and PANI–phenothiazine (P3) are designed with different energy levels to modify the interface between PEDOT:PSS and the perovskite layer and improve the device performance. The effects of the polymers on the device performance are demonstrated by evaluating the work function adjustment, perovskite growth control, and interface modification in MAPbI3‐based PSCs. Low bandgap Sn–Pb‐based PSCs are also fabricated to confirm the effects of the polymers. Three effects are evaluated through the comparison study of PEDOT:PSS‐based organic solar cells and MAPbI3 PSCs based on the PEDOT:PSS modified by P1, P2, and P3. The order of contribution for the three effects is work function adjustment > surface modification > perovskite growth control. MAPbI3 PSCs modified with P2 exhibit a high Voc of 1.13 V and a high‐power conversion efficiency of 21.06%. This work provides the fundamental understanding of the interface passivation effects for PEDOT:PSS‐based optoelectronic devices.

Hydrogenase enzymes produce H 2 gas, which can be a potential source of alternative energy. Inspired by the [NiFe] hydrogenases, we report the construction of a de novo-designed artificial hydrogenase (ArH). The ArH is a dimeric coiled coil where two cysteine (Cys) residues are introduced at tandem a/d positions of a heptad to create a tetrathiolato Ni binding site. Spectroscopic studies show that Ni binding significantly stabilizes the peptide producing electronic transitions characteristic of Ni-thiolate proteins. The ArH produces H 2 photocatalytically, demonstrating a bell-shaped pH-dependence on activity. Fluorescence lifetimes and transient absorption spectroscopic studies are undertaken to elucidate the nature of pHdependence, and to monitor the reaction kinetics of the photochemical processes. pH titrations are employed to determine the role of protonated Cys on reactivity. Through combining these results, a fine balance is found between solution acidity and the electron transfer steps. This balance is critical to maximize the production of Ni I -peptide and protonation of the Ni II À H À intermediate (NiÀ R) by a Cys (pK a � 6.4) to produce H 2 .

Shortwave infrared (SWIR) dyes are characterized by their ability to absorb light from 900 to 1400 nm, which is ideal for deep tissue imaging owing to minimized light scattering and interference from endogenous pigments. An approach to access such molecules is to tune the photophysical properties of known near‐infrared dyes. Herein, we report the development of a series of easily accessible (three steps) SWIR xanthene dyes based on a dibenzazepine donor conjugated to thiophene (SCR‐1), thienothiophene (SCR‐2), or bithiophene (SCR‐3). We leverage the fact that SCR‐1 undergoes a bathochromic shift when aggregated for in vivo studies by developing a ratiometric nanoparticle for NO (rNP‐NO), which we employed to successfully visualize pathological levels of nitric oxide in a drug‐induced liver injury model via deep tissue SWIR photoacoustic (PA) imaging. Our work demonstrates how easily this dye series can be utilized as a component in nanosensor designs for imaging studies.

Excess Electron Binding Site of the Class I Isomers. -(ROSCIOLI, J. R.; HAMMER, N. I.; JOHNSON*, M. A.; J. Phys. Chem. A 110 (2006) 24, 7517-7520; Sterling Chem. Lab., Yale Univ., New Haven, CT 06511, USA; Eng.) -Schramke 35-002 O) -n=3-24