Review of the period July 2007–December 2009

Angelo Albini

DOI: 10.1039/9781849730860-00001

1 A bit of history

Anniversaries have come up in these years. The present reporter has remarked that a century has elapsed since photochemistry came of age. The chemical effects that light produced had of course been known since the beginning of chemistry itself and the interest had much grown in the 19th Century due to the development of photography. However, photochemical experiments had remained sparse and conclusive evidence about the exact nature of that effect had been very limited until the beginning of the following century, when things changed mainly thanks to the contribution by Ciamician and Silber and by Paterno` in Italy and by Stobbe in Germany.

All of the three groups published their view of the state of the art in 1909 and recognized the great advancement that had taken place. It is indeed remarkable that most of the key reactions of (unsaturated) carbonyl derivatives, nitro compounds and alkenes, oxygenations reactions and photochromism were then discovered and rationalized in a way that has resisted time.

In the hundred years since, photochemistry has been first neglected, then has taken a considerable time in rediscovering what had been in meantime forgotten. When this happened, however, (in the 1950s) the understanding of molecular structure and bonding had much grown and the new 'molecular' photochemistry, as indicated in the title of Turro's book became an essential part of 'mechanistic' chemistry in research and in university courses. The first volume of the present Royal Chemical Society series edited by D. Bryce-Smith was printed 40 years ago at the high mark of this process and represented photochemistry as a consistent and articulated theory, growing at a lively pace in different (applicative) directions.

After four decades, what most impresses an observer is how far the applications of photochemistry has become detached from the core of the discipline. Indeed, photochemistry has pervaded fields so far one from another that they are not only independent one from another, but are even forgetful that there is a single core discipline.

2 Photochemical literature: the present state

Examining the photochemical literature in the 2 1/2 years period considered, one first of all notices that this discipline has an important role and certainly advances at no slackened pace, with regard to both research papers and patents. The yearly number of photochemical papers is since some time essentially unchanged. A more detailed consideration evidences some characteristics of the photochemical literature that had been highlighted in the Introduction to the previous volume.

Thus, if one takes into consideration the journals that have most often hosted photochemical papers, as an example referring to year 2009, and lists the journals according to the number of papers on this subject published that year, one find that 32 journals contained about 35% of the total number of the papers of that year. The type of journal is an indication of the audience that photochemistry practitioners think to address. What comes out is that the percentage of papers is distributed according to the key topic of the journal as follows.

– General chemistry, 6.6% of the total (JACS, the single journal most often chosen makes 3.2 %, the others are Chem. Commun., Angew. Chem., Chem. Eur. J., Proc. Natl. Acad. Sci.)

– Physical chemistry, 7% (J. Phis. Chem. A, B, C, Phys. Chem. Chem. Phys., Chem. Phys. Lett.)

– Organic chemistry 2.6% (J. Org. Chem, Org. Lett., Org. Biom. Chem.)

– Inorganic chemistry 2.1% (Inorg. Chem., Dalton Trans.)

– Materials and surfaces 5.1% (J. Hazard. Mat., J. Mater. Chem., Langmuir, J. Coll. Inter. Sci.)

– Environment 3.7% (Env. Sci. Technol., Atm. Chem., Atm. Environ., Chemosph.)

Further topics among the most used specialist journals containing photochemical papers are catalysis (Appl. Cat. B), applied physics (Proc. SPIEE, Opt. Express), polymer science (J. App. Pol. Sci.), biochemistry (Biochem.).

As remarked in the introduction to Vol. 37 in this series, a noticeable fact is the relatively small amount of papers published in journals specifically devoted to photochemistry. The three journals in the field (J. Photochem. Photobiol., Photochem. Photobiol.,Photochem. Photobiol Sci.) make together 3.5% of the total (see Fig. 1), a half of the papers in the general chemistry category and a much smaller number than in other fields.

In the opinion of the present reporter, this fact does not necessarily imply a negative connotation. It simply indicates that photochemistry is important in many fields and plays a role in each of them that is felt more important than that in photochemistry itself. In particular, remarkable is the high fraction of papers in general chemistry journals, the largest part of them appearing as fast communication in prestigious journals, an indication of the recognized position that this discipline has maintained. The use of devoted journals is much more extensive in other chemical disciplines, e.g. in electrochemistry, but this has little to do with the importance and the role that each discipline has.

The determining fact is that dedicated journals are available so that any scientist can refer to them for good science, if a further portion of good science is found elsewhere, no problem. In this sense, if a concern must be expressed, this is rather that photochemistry, while remaining in the first line, has lost some position with respect to other advancing fields. As an example, if one considers JACS, inevitably the...