Studies on Heterocyclic Colouring Matters Part III: 7a,14a-diaza-7,7a,14,14a-tetrahydroquino[2,3-b]acridine-7,14-diones (5,7a,12,14a-tetraaza-7,7a,14,14a-tetrahydropentacene-7,14-diones)

2-Aminopyridines react with diethyl 2,5-dioxo-cyclohexane-1,4-dicarboxylate (diethyl succinylsuccinate) to give 7a,14a-diaza-6,7,7a,13,14,14a-hexahydroquino-[2,3-b] acridine-7,14-diones (5,7a,1,14a-tetraaza-6,7,7a,13,14,14a-hexahydropentacene-7,14-diones), which are aromatized to the title compounds. Oxidation of these with a mixture of sulfuric and nitric acids results in the formation of their respective 6,13-quinones, also obtained directly from 2-aminopyridines and diethyl 2,5-dichloro-1,4-benzoquinone-3,6-dicarboxylate. The chromophore of the title compounds is compared with that of quinacridones.     

Electrochemical behavior of n-and p-type GaxIn1−xP electrodes in sodium iodide liquid ammoniate at room temperature

The electrochemical behavior of p- and n-type Ga_xIn_1-xP electrodes in liquid ammoniate (NaI+3.3 NH₃) in the dark and under illumination has been investigated at room temperature. The flatband potentials of the semiconductors (SC) have been measured either by impedance determinations or by the photoperturbation method. Some specific physical parameters of the polycrystalline material have been deduced, such as E_gap, the electronic transition modes and the carrier densities. The SC behavior in water and in liquid ammoniate has been compared.     

ASP fits to multi-way layouts

The balanced complete multi-way layout with ordinal or nominal factors is a fundamental data-type that arises in medical imaging, agricultural field trials, DNA microassays, and other settings where analysis of variance (ANOVA) is an established tool. ASP algorithms weigh competing biased fits in order to reduce risk through variance-bias tradeoff. The acronym ASP stands for Adaptive Shrinkage of Penalty bases. Motivating ASP is a penalized least squares criterion that associates a separate quadratic penalty term with each main effect and each interaction in the general ANOVA decomposition of means. The penalty terms express plausible conjecture about the mean function, respecting the difference between ordinal and nominal factors. Multiparametric asymptotics under a probability model and experiments on data elucidate how ASP dominates least squares, sometimes very substantially. ASP estimators for nominal factors recover Stein's superior shrinkage estimators for one- and two-way layouts. ASP estimators for ordinal factors bring out the merits of smoothed fits to multi-way layouts, a topic broached algorithmically in work by Tukey. This research was supported in part by National Science Foundation Grants DMS 0300806 and 0404547.     

Quinacridones: Structure and Mechanism of Formation

The NMR. spectra of two acridones and twenty-two quinacridones in (CD₃)₂SO? NaOD are reported. A NMR. technique is described for determining the composition of mixtures of various substituted quinacridones. A general mechanism is proposed for quinacridone formation via cyclodehydration of 2,5-diarylamino-terephthalic and 2,5-diarylamino-1,4-benzoquinone-3,6-dicarboxylic acids/esters.