UV-visible spectra have been studied for a series of p-substituted tetraphenylporphyrins (TPPs) titrated with strong acid in various solvents. Substituent effects on the Soret and Q(I) absorption peaks and the fluorescence emission peaks have been treated by Hammett correlations. In general, there are only small effects with electron-withdrawing substituents, but electron-donating substituents lead to lower energy transitions, with especially strong effects observed in the case of the diprotonated porphyrins with good electron-donating substituents (hyperporphyrin effects). The hyperporphyrin effects are attributed to the crossing of a π molecular orbital on the substituted phenyl group above the usual porphyrin π highest occupied molecular orbital. For the neutral TPPs, this crossing is estimated to occur with a substituent as electron-donating as p-methoxy, and for the diprotonated TPPs, the crossing occurs at approximately unsubstituted TPP. Distinctive solvent effects on the spectra and the Hammett correlations are observed.

No abstract

No abstract

Analysis of child sexual abuse images, commonly referred to as pornography, requires a familiarity with the sexual maturation rating of children and an understanding of growth and development parameters. This article explains barriers that exist in working in this area of child abuse, the differences between subjective and objective analyses, methods used in working with this form of contraband, and recommendations that analysts document their findings in a format that allows for verbal descriptions of the images so that the content will be reflected in legal proceedings should there exist an aversion to visual review. Child sexual abuse images are a digital crime scene, and analysis requires a careful approach to assure that all victims may be identified.