Publications

A general synthetic strategy for the construction of large, nitrogen-containing polycyclic aromatic hydrocarbons (PAHs) is reported. The strategy involves two key steps: (1) a titanocene-mediated reductive cyclization of an oligo(dinitrile) precursor to form a PAH appended with di(aza)titanacyclopentadiene functionality; (2) a divergent titanocene transfer reaction, which allows final-step installation of one or more o-quinone, diazole, or pyrazine units into the PAH framework. The new methodology enables rational, late-stage control of HOMO and LUMO energy levels and thus photophysical and electrochemical properties, as revealed by UV/vis and fluorescence spectroscopy, cyclic voltammetry, and DFT calculations. More generally, this contribution presents the first productive use of di(aza)metallacyclopentadiene intermediates in organic synthesis, including the first formal [2 + 2 + 2] reaction to form a pyrazine ring.

For the past two years,there has been a significant increase in research activities related to studying and modeling the Internet's topology, especially at the level of autonomous systems (ASs). A closer look at the measurements that form the basis for all these studies reveals that the data sets used consist of the BGP routing tables collected by the Oregon route server (henceforth, the Oregon route-views ) [1]. So far, there has been anecdotal evidence and an intuitive understanding among researchers in the field that BGP-derived AS connectivity is not complete. However, as far as we know, there has been no systematic study on quantifying the completeness of currently known AS-level Internet topologies. Our main objective in this paper is to quantify the completeness of Internet AS maps constructed from the Oregon route-views and to attempt to capture more representative AS-level Internet topology. One of the main contributions of this paper is in developing a methodology that enables quantitative investigations into issues related to the (in)completeness of BGP-derived AS maps.

The synthesis and reactivity of monomeric, 16-electron hafnocene silyl hydride complexes are described. The complex CpCp*Hf[Si(SiMe3)3]H (1; Cp* = η5-C5Me5), prepared by the reaction of CpCp*Hf(H)Cl with (THF)3LiSi(SiMe3)3, reacts rapidly with both ethylene and diphenylacetylene with elimination of HSi(SiMe3)3 to afford the corresponding hafnacyclopentane and tetraphenylhafnacyclopentadiene complexes. Complex 1 reacts with acetone to give the insertion product CpCp*Hf(OCHMe2)[Si(SiMe3)3] (4). Reaction of 1 with the secondary silane H2Si(SiMe3)2 proceeds smoothly to the new silyl hydride complex CpCp*Hf[SiH(SiMe3)2]H (5), which was characterized by X-ray crystallography. Deuterium labeling experiments indicate that the latter reaction occurs with significant scrambling of label between the SiH and HfH positions. The tertiary silane Ph3SiH does not react under comparable conditions. The silane H2Si(SiMe3)2 undergoes a similar σ-bond metathesis reaction with CpCp*Hf[Si(SiMe3)3]Cl, to give CpCp*Hf[SiH(SiMe3)2]Cl (7). For the latter reaction, there is a photochemical dependence on the rate and course of the reaction pathway. Exposure of the reaction mixture to room light is critical for complete conversion to 7.

The transition metal-catalyzed anti-Markovnikov hydroamination of unactivated vinylarenes with a rhodium complex of DPEphos is reported. The reaction of electron-neutral or electron-rich vinylarenes with a variety of secondary amines in the presence of catalyst forms the products from anti-Markovnikov hydroamination in high yields. Reactions of morpholine, N-phenylpiperazine, N-Boc-piperazine, piperidine, 2,5-dimethylmorpholine, and perhydroisoquinoline reacted with styrene to form the amine product in 51-71% yield. Reactions of a variety of vinylarenes with morpholine generated amine as the major product. Reactions of morpholine with electron-poor vinylarenes gave lower amine:enamine ratios than reactions of electron-rich vinylarenes at the same concentration of vinylarene, but conditions were developed with lower concentrations of electron-poor vinylarene to maintain formation of the amine as the major product. Reactions of dimethylamine with vinylarenes were fast and formed amine as the major product. Mechanistic studies on the hydroamination process showed that the amine:enamine ratio was lower for reactions conducted with higher concentrations of vinylarene and that one vinylarene influences the selectivity for reaction of another. A mechanism proceeding through a metallacyclic intermediate that opens in the presence of a second vinylarene accounts for these and other mechanistic observations.

Understanding patient responsiveness, a component of fidelity, is essential as it impacts treatment outcome and ongoing use of treatment elements. This study evaluated patient responsiveness-operationalized as receptivity to treatment modules and ratings of the usefulness and the utilization of treatment elements-to the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TranS-C) in a sample of adults with serious mental illness (SMI) and sleep/circadian dysfunction. Adults with SMI and sleep/circadian dysfunction (N = 104) received TranS-C in a community mental health setting. Independent raters rated TranS-C sessions to assess receptivity. At posttreatment and 6-month follow-up, participants completed a usefulness scale, utilization scale, the PROMIS Sleep Disturbance (PROMIS-SD) and Sleep-Related Impairment (PROMIS-SRI) scales, DSM-5 Cross-Cutting Measure (DSM-5-CC), and Sheehan Disability Scale (SDS). Receptivity was rated as somewhat to fully understood, and predicted a reduction on the DSM-5-CC. On average, participants rated TranS-C as moderately useful and utilized treatment elements occasionally. Ratings of usefulness were associated with the PROMIS-SD, PROMIS-SRI, and DSM-5-CC at posttreatment, but not with the SDS. Ratings of utilization were not associated with outcome. The findings add to the literature on patient responsiveness, an implementation outcome, and provide data on the utility of TranS-C within a community mental health setting.