Evaluation of a multimedia case-history simulation program for pharmacy students.

http://www.ajpe.org/view.asp?art=aj670116&pdf=ye

Structural, Spectroscopic, and Electrochemical Studies of Binuclear Manganese(II) Complexes of Bis(pentadentate) Ligands Derived from Bis(1,4,7-triazacyclononane) Macrocycles

Structural, electrochemical, ESR, and H2O2 reactivity studies are reported for [Mn(dmptacn)Cl]ClO4 (1, dmptacn = 1,4-bis(2-pyridylmethyl)-1,4,7-triazacyclononane) and binuclear complexes of bis(pentadentate) ligands, generated by attaching 2-pyridylmethyl arms to each secondary nitrogen in bis(1,4,7-triazacyclononane) macrocycles and linked by ethyl (tmpdtne, [Mn2(tmpdtne)Cl2](ClO4)2·2DMF, 2), propyl (tmpdtnp, [Mn2(tmpdtnp)Cl2](ClO4)2· 3H2O, 3), butyl (tmpdtnb, [Mn2(tmpdtnb)Cl2](ClO4)2·DMF·2H2O, 4), m-xylyl (tmpdtn-m-X, [Mn2(tmpdtn-m-X)-Cl2](ClO4)2, 5) and 2-propanol (tmpdtnp-OH, [Mn2(tmpdtnp-OH)Cl2](ClO4)2, 6) groups. 1 crystallizes in the orthorhombic space group P212121 (No. 19) with a = 7.959(7) Å, b = 12.30(1) Å, and c = 21.72(2) Å; 2, in the monoclinic space group P2(1/c) (No. 14) with a = 11.455(4) Å, b = 15.037(6) Å, c = 15.887(4) Å, and β = 96.48(2)°; 3, in the monoclinic space group P2(1/c) (No. 14) with a = 13.334(2) Å, b = 19.926(2) Å, c = 18.799-(1) Å, and β = 104.328(8)°; and [Mn2(tmpdtnb)Cl2](ClO4)2·4DMF·3H2O (4'), in the monoclinic space group P2(1/n) (No. 14) with a = 13.361(3) Å, b = 16.807(5) Å, c = 14.339(4) Å, and β = 111.14(2)°. Significant distortion of the Mn(II) geometry is evident from the angle subtended by the five-membered chelate (ca. 75°) and the angles spanned by trans donor atoms (<160°). The Mn geometry is intermediate between octahedral and trigonal prismatic, and for complexes 2-4, there is a systematic increase in M···M distance with the length of the alkyl chain. Cyclic and square-wave voltammetric studies indicate that 1 undergoes a 1e- oxidation from Mn(II) to Mn(III) followed by a further oxidation to Mn(IV) at a significantly more positive potential. The binuclear Mn(II) complexes 2-5 are oxidized to the Mn(III) state in two unresolved 1e- processes {Mn(II)2 → Mn(II)Mn(III) → Mn(III)2} and then to the Mn(IV) state {Mn(III)2 → Mn(III)Mn(IV) → Mn(IV)2}. For 2, the second oxidation process was partially resolved into two 1e- oxidation processes under the conditions of square-wave voltammetry. In the case of 6, initial oxidation to the Mn(III)2 state occurs in two overlapping 1e- processes as was found for 2-5, but this complex then undergoes two further clearly separated 1e- oxidation processes to the Mn(II)Mn(IV) state at +0.89 V and the Mn(IV)2 state at +1.33 V (vs Fc/Fc+). This behavior is attributed to formation of an alkoxo-bridged complex. Complexes 1-6 were found to catalyze the disproportionation of H2O2. Addition of H2O2 to 2 generated an oxo-bridged mixed-valent Mn(III)Mn(IV) intermediate with a characteristic 16-line ESR signal

Intra-specific differences in root and shoot glucosinolate profiles among white cabbage (Brassica oleracea var. capitata) cultivars

Shoot glucosinolate profiles of Brassicaceae are known to vary within species, across environmental conditions, and between developmental stages. Here we study whether root profiles follow the intra-specific, environmental, and developmental variation observed for aerial parts in white cabbage cultivars. We also assess whether greenhouse studies can be used to predict shoot and root glucosinolate concentrations and profiles in the field. Root glucosinolate profiles showed significant intra-specific variation; however, this variation was unrelated to that in shoot profiles. One of the strongest determinants of the diversity in the root profiles was 2-phenylethyl glucosinolate (gluconasturtiin). Root profiles were generally comparable between greenhouse studies and field trials, whereas shoot profiles were highly plastic. We conclude that among white cabbage cultivars, shoot glucosinolate profiles are not indicative of root profiles. We further conclude that greenhouse assessments of root glucosinolates can be reliable predictors of root glucosinolate profiles in the field due to their low plasticity.