Cover Art Gallery

94.  DOI: 10.1021/jo000487u

95.  DOI: 10.1021/jo0004862

96.  DOI: 10.1021/jo000488m

97.  DOI: 10.1021/jo000489e

98.  DOI: 10.1021/jo000490d

Electrical addressing of self-assembled monolayers of porphyrin-based molecules enables the storage of multiple bits of information. Five distinct types of molecular architectures have been synthesized for investigating molecular information storage. 

147.  DOI: 10.1021/ic034558u

Self-assembled dyads of porphyrins have been prepared via imine condensations for light harvesting studies. A triad composed of two porphyrins and an intervening bis(dipyrrinato)zinc complex also self-assembles from porphyrins bearing a free-base dipyrrin in the presence of a zinc salt. The bis (dipyrrinato)zinc unit absorbs blue-green light and transfers the excited-state energy in ~ 2 ps to the porphyrins, which emit red light. Thus, the bisdipyrrinato)zinc unit serves the dual roles of a self-assembling architectural element (linker) and an accessory pigment for light harvesting.

152.  DOI: 10.1021/jo034944t

153.  DOI: 10.1021/jo034945l

154.  DOI: 10.1021/jo034946d

155.  DOI: 10.1021/jo0349476

Ultra-dense information storage media may be obtained by use of redox-active (charge-storage) molecules attached to electroactive surfaces. Synthetic routes have been developed for preparing diverse porphyrinic molecules bearing tethers (single or tripodal) terminated with oxygen, sulfur, selenium, or phosphonic acid groups for attachment to metals (e.g., Au), semiconductors (e.g., Si, SnO2, TiO2), or insulators (e.g., SiO2).  The molecules exhibit up to four cationic states, affording multibit storage capabilities. The image is the United States Library of Congress.

235.  DOI: 10.1039/B717803D 

Synthetic bacteriochlorins are analogues of Nature’s near-infrared light-harvesting molecules, bacteriochlorophylls, and enable new vistas for diverse applications.  The musical score is from Mussorgsky “Pictures at an Exhibition.”

258.  DOI: 10.1021/jo9002954 

The cover shows an orderly “garden of synthetic chlorophylls” in the foreground of a wild and unruly natural landscape, which illustrates the possibilities of synthetic chlorophylls.  The sparsely substituted synthetic macrocycles – readily constructed from simple precursors and then successively substituted in a regioselective manner to form the isocyclic ring and access the key 7-position – are valuable for fundamental spectroscopic studies. 

276.  DOI: 10.1039/C0NJ00716A 

Under plausible prebiotic conditions in aqueous solution, the reaction of two small molecules affords a pyrrole that subsequently self-condenses to form a porphyrinogen analogous to uroporphyrinogen III, Nature’s universal precursor to all extant biosynthesized tetrapyrrole macrocycles. The journal cover art accompanying this article was prepared by Ms. Margot Geist (www.geistlight.com) using a seascape image obtained at Cape Perpetua, Oregon.

291.  DOI: 10.1142/S1088424612004628

Combinatorial libraries of β-substituted tetrapyrrole macrocycles are rich in isomers due to the location and relative orientation of the substituents.  A software program (PorphyrinViLiGe) and accompanying terminology enable description of the libraries, their members, and the subsets of isomers located therein.  The libraries can be vast: derivatization of an 8-point tetrapyrrole scaffold with 8 reagents affords >2 million members, of which >99% are isomers of other members of the library.  The diverse macrocycles are shown in the firmament with the Andromeda galaxy (courtesy NASA/JPL-Caltech). 

320.  DOI: 10.1142/S1088424614500199

Bacteriochlorophyll a is employed by photosynthetic bacteria for light-gathering and energy transduction in diverse aquatic environments.  Rational chemical synthesis has provided a set of bacteriochlorins with pairwise isotopic substitution in the macrocycle framework.  NMR spectroscopy reported here of the set provides valuable information for understanding substitution effects and aromaticity in the natural macrocycles.  The serene backdrop – encompassing plant, algal, and bacterial photosynthesis in early spring – is of Atkinson’s Lake near Rockport, Indiana.

327.  DOI: 10.1142/S1088424615500042 

Chlorophyll a, the chief photosynthetic pigment in plants, constitutes the thin layer of pigment that blankets the globe, captures sunlight, and powers the biosphere. Rational chemical synthesis now enables access to chlorophyll analogues with control over essentially all sites about the perimeter of the macrocycle. Sparsely substituted chlorins can be prepared for a range of fundamental studies. The verdant landscape is west-ward facing in Muir Woods National Monument, Mill Valley, California.

355.  DOI: 10.1039/C6NJ04135C

Keto groups are potent auxochromes in hydroporphyrins such as chlorins and bacteriochlorins, causing hypsochromic or bathochromic shifts depending on location about the perimeter of the macrocycle, and thereby altering light-harvesting capacity.  The backdrop is the shore at Okinawa (Odo beach, Itoman city, Okinawa prefecture, Japan).

371. DOI: 10.1039/C8NP00020D

Chlorophylls, bacteriochlorophylls and related hydroporphyrins constitute invaluable natural products but have largely remained outside the scope of viable syntheses. Even the famous synthesis of Woodward was incomplete.  Quantitative analysis of cumulative reaction mass efficiency (cRME) establishes benchmarks for viable syntheses in this domain. The backdrop is at the Hawaiʻi Tropical Botanical Garden near Papaikou, Hawaiʻi.

428. DOI: 10.1021/acs.jnatprod.2c00720

Flavonoids comprise a rich collection of secondary metabolites. The black locust tree, Robinia pseudoacacia, contains multiple flavonoids, including glycosides of acacetin, apigenin, luteolin, and quercetin shown here. The present database of absorption spectra should facilitate identification of diverse flavonoids. Image at La Roseraie de Provins, France, by Jonathan S. Lindsey.

440. DOI: 10.1142/S1088424623501171

The development of bacteriochlorin synthetic chemistry is inspired by the native bacteriochlorophyll a, the chief pigment of anoxygenic photosynthetic bacteria.  The backdrop of the image is a view from the mountains of North Carolina facing toward Raleigh, where the work in bacteriochlorin chemistry of Jonathan Lindsey and his research group has been carried out over the years.

453. DOI: 10.1039/D4NJ01533A

Phyllobilins – derived from chlorophyll – are abundant plant natural products.  The verdant backdrop is from ʻAkaka Falls State Park, Hawaiʻi.  The labels were handwritten by the first author.