Described is the construction of an ultrafast electrochromic window. One electrode of this window is based on a transparent nanostructured TiO 2 (anatase) film (4.0 µm thick) supported on conducting glass (F-doped tin oxide, 10 Ω cm -2 , 0.5 µm thick) and modified by chemisorption of a monolayer of the redox chromophore bis(2-phosphonoethyl)-4,4′-bipyridinium dichloride. The other electrode is based on a transparent nanostructured SnO 2 film (3.0 µm thick) supported on conducting glass (F-doped tin oxide, 10 Ω cm -2 , 0.5 µm thick) and modified by chemisorption of a monolayer of the redox chromophore [β-(10-phenothiazyl)propoxy]phosphonic acid. The electrolyte used is LiClO 4 (0.2 mol dm -3 ) in γ-butyrolactone. The excellent performance of a 2.5 cm × 2.5 cm window over 10 000 electrochromic test cyclessswitching times (coloring and bleaching) of less than 250 ms, coloration efficiency of 270 cm 2 C -1 , steady-state currents (colored and bleached) of less than 6 µA cm -2 , and memory of greater than 600 s (time required for low end transmittance to increase by 5%)ssuggest a practical technology.

Despite much recent interest in the flipped classroom, quantitative studies are slowly emerging, particularly in the sciences. We report a year-long parallel controlled study of the flipped classroom in a second-term general chemistry course. The flipped course was piloted in the off-semester course in Fall 2014, and the availability of the flipped section in Spring 2015 was broadly advertised prior to registration. Students self-selected into the control and flipped sections, which were taught in parallel by the same instructor; initial populations were 206 in the control section, 117 in the flipped. As a pretest, we used the ACS first-term general chemistry exam (form 2005), given as the final exam across all sections of the first-term course. Analysis of pretest scores, student percentile rankings in the first-term course, and population demographics indicated very similar populations in the two sections. The course designs required comparable student effort, and five common exams were administered, including as a final the ACS second-term general chemistry exam (form 2010). Exam items were validated using classical test theory and Rasch analysis. We find that exam performance in the two sections is statistically different only for the bottom third, as measured by pretest score or percentile rank; here improvement was seen in the flipped class across all five exams. Following this trend was a significant (56%) decrease in DFW percentage (Ds, Fs, withdrawals) in the flipped courses as compared with the control. While both courses incorporated online homework/assessments, the correlation of this indicator with exam performance was stronger in the flipped section, particularly among the bottom demographic. We reflect on the origin and implication of these trends, using data also from student evaluations.

Fe(P)(NO), where P = TPP, TPC, or OEP, is reduced in three one-electron steps in nonaqueous solvents. The products of the first two waves (Fe(P)(NO)" and Fe(P)(NO)2") were stable, and the visible spectra were obtained by using OTTLE spectroelectrochemistry. The vibrational spectra of Fe(P)(NO) and its first reduction product obtained coulometrically were recorded. The porphyrin vibrations for both species were consistent with low-spin ferrous complexes. The vno and vfc-n bands could also be observed for both complexes, though i>n0 for Fe(TPP)(NO)" was quite weak. For Fe(TPP)(NO), vN0 (15N values in parentheses) was 1681 cm"1 (1647 cm"1) and vFe_N was 525 cm"1 (517 cm"1). Upon reduction, vN0 decreased to 1496 cm"1 (1475 cm"1) while vFe-N increased to 549 cm"1 (538 cm"1). These results were consistent with the addition of the electron to the half-filled d,2 + orbital, which is formed from * 0 and iron dz2 orbitals. Therefore, addition of an electron to this orbital would lead to a strengthening of the Fe-N bond and a weakening of the N-O bond. Dc polarography of Fe(TPP)(NO) and Fe(TPC)(NO) was carried out in the presence of several substituted phenols. The limiting current and half-wave potential of the first wave were unaffected by the presence of the phenols, except at high phenol concentrations. A new second wave appeared, though, in the presence of phenols, and the limiting current and half-wave potential for this wave depended strongly on the concentration and identity of the weak acid. The overall reduction appeared to involve three electrons on the polarographic time scale, to yield Fe(P)" and hydroxylamine. Further reduction to ammonia was observed on the coulometric time scale. Exhaustive electrolysis gave ammonia in nearly quantitative yield for 2-chlorophenol concentrations greater than 20 mM. No differences were observed in the polarographic behavior of Fe(TPP)(NO) and Fe(TPC)(NO), but somewhat higher concentrations of 2-chlorophenol were needed to generate ammonia coulometrically.

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