Chemical world This week
The Top Stories A porphyrin—bispyridylmagnesiumtetrabenzoporphine—has been detected in deep space. Its discoverer predicts that other complex molecules also are present among the stars 5 The assertion that enzyme struc tures are the same in crystals and in solution is questioned for at least one enzyme 6 Phthalate esters, used in large quantities as plasticizers, may be important water pollutants, a sci entist from the U.S. Department of the Interior says 8 Discipline and demand in the chemical industry are boosting productivity, a key to decisions in Nixon's Phase II economy 10 Senate deliberates consumer laws that would drastically alter existing laws and consolidate safety regu lation into single independent agency 16 Liquid crystals are drawing intense interest. Their unusual physical and optical properties give them important potential technical applications 20 Fewer company recruiters are making visits to campuses this year; many companies are plan ning to hire fewer graduates 26 It's a grim year for starting salaries. Those for chemists and chemical engineers are down as unemploy ment reaches all-time high for re cent graduates 28
November 1, 1971
PORPHYRIN IN SPACE Certain lines—known as diffuse in terstellar lines—in optical spectra taken of interstellar space match conclusively the spectrum of bispyridylmagnesium t e t r a b e n z o p o r phine (MgC 46 H 3 ON 6 ), according to Dr. Fred M. Johnson, chairman of the physics department of Califor nia State College. Having thus identified the largest molecule yet to be detected in deep space after 18 years of work, Dr. Johnson, at the recent Pacific Conference on Chemistry and Spectroscopy in Ana heim, Calif., went on to predict the existence in space of other complex molecules essential to life on earth including other porphyrins—chloro phyll and its precursors, for ex ample—pyridine, and various hy drocarbons including benzene. Johnson: 18 years' work (About a dozen much smaller spe cies, including formic acid, methyl alcohol, ammonia, and cyanoacetylene, have been detected in inter stellar space by radioastronomers, 10 of them in the past two years.) Dr. Johnson first began work on identification of the diffuse inter stellar lines in the early 1950's at Columbia University. In 1963 he went to the West Coast and ob tained a list of some 25 optical spectra lines from G. H. Herbig of California's Lick Observatory. He began comparing the lines to spec tra of known compounds and in 1964 noticed some regularities in the spacings of the lines that sug gested vibronic transitions in com plex hydrocarbon molecules. In 1966, while doing spectroscopic studies of some porphyrins, namely the hemes, he noticed a crude simi larity to the diffuse interstellar lines. The strongest interstellar Deep space: interstellar lines line, at 4428 Α., corresponded closely to the strongest band (Soret phyrin molecule from which he was band) of the porphyrins. able to piece together enough spec Dr. Johnson then began looking tral lines to account for most of the at the spectra of the most stable diffuse interstellar lines. known porphyrins. And with the Why porphyrins? Porphyrins are help of Dr. Charles E. Castro of the unique not only for their impor University of California, Riverside, tance to life processes such as who synthesized a number of por photosynthesis (chlorophyll) and phyrins, Dr. Johnson found a por- respiration (cytochrome), but also NOV. 1, 1971 C&EN 5
