Researchers from North Carolina State University have successfully synthesized bacteriochlorophyll a , a photosynthetic pigment found in bacteria which absorbs infrared light. The work represents the first chemical synthesis of this molecule and could give scientists deeper insights into photosynthetic function and photosynthetic energy.
“There are two ‘worlds’ of photosynthesis: the green plant-based world that all of us are familiar with, and a microbial world that represents a simpler form of photosynthesis where no oxygen is made,” says Jonathan Lindsey, Glaxo Distinguished University Professor of Chemistry at NC State and corresponding author of the research.
“These photosynthetic microbes have been intensively studied as a cornerstone of basic science in the field of photosynthesis,” Lindsey says. “But their light-absorbing pigments have not been targets of chemical synthesis.”
This is due, in part, to the structure of the bacteriochlorophyll a molecule, a large, disc-shaped molecule, or macrocycle, composed of five rings of atoms. Structurally, the outer fifth ring – known as ring E – has always been a challenge for chemists.
Prior approaches to synthesizing the macrocycle have consisted of creating the four inner rings and then attempting to bolt ring E to the outside. But the NC State group took a different approach.
“Ring E, the fifth ring, was always regarded as this final mountain that had to be climbed,” says Duy Chung, who received his Ph.D. from NC State while conducting the research.
“What we did was synthesize both halves of the macrocycle, then use constituents of ring E as the joining site for bringing the two halves together,” Chung says. “When the halves are attached to an atom that will eventually become ring E, a cascade reaction triggers and the molecule self-assembles in the last step.” Chung is the first author of the paper.
The researchers hope that the strategy can be used to synthesize other photosynthetic macrocycles of interest, leading to increased exploration in photosynthesis and energy sciences.
“This self-assembly method may open access to the whole family of molecules,” Lindsey says. “And from there we can make specific derivatives for experimentation.
“It’s always been striking to me that molecular biologists can go in and do all kinds of gene manipulations to create modified organisms and tailor the proteins that hold these pigments, but the pigments themselves could not be created from scratch by methods of chemical synthesis. But that’s what we’ve been able to do here – create a method for synthesizing these macrocycles.”
The work appears in Chemical Science and is supported by the National Science Foundation under grant CHE-2348052. Former NC State Ph.D. students Khiem Chau Nguyen and Yizhou Liu also contributed to the research.
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Note to editors : An abstract follows.
“Synthesis of bacteriochlorophyll a ”
DOI: 10.1039/d5sc10233b
Authors: Duy Chung, Khiem Nguyen, Yizhou Liu, North Carolina State University
Published : April 10, 2026 in Chemical Science
Abstract:
Photosynthetic tetrapyrroles absorb light to power the biosphere but have largely been neglected as targets of chemical synthesis. Bacteriochlorophyll a – a key macrocycle in the bacterial photosynthetic reaction center – contains four stereocenters at the rim of the bacteriochlorin chromophore due to the transdialkyl group in each pyrroline ring (B, D), and an epimerizable b-ketoester embedded in the isocyclic ring (E). Here, each pair of stereodefined vicinal substituents was introduced as a chiral 4-nitroalkanal building block, which was converted to an alkynone for subsequent coupling with an iodopyrrole (A, C), affording the AD and BC dihydrodipyrrins. The dihydrodipyrrins were equipped with reactive groups (1-formyl, AD-half; 1-(1,1-dimethoxymethyl) and 8-(3-methoxy-1,3-dioxopropyl, BC-half) suited for directed macrocycle formation. Knoevenagel condensation of AD and BC halves afforded a propenone, the nexus for constructing ring E concomitantly with the macrocycle in the subsequent one-flask, double-ring closure (Nazarov cyclization, electrophilic aromatic substitution, elimination of methanol). The aromatic bacteriopheophorbide was obtained as the 2-trimethylsilylethyl propanoate, which upon acidolysis and esterification with phytol yielded bacteriopheophytin a; subsequent magnesiation gave bacteriochlorophyll a. The modularity of the synthesis, straightforward construction of asymmetric building blocks, and convergent joining of AD and BC halves suggest that the present route may provide an entr´ee into diverse photosynthetic macrocycles.
Chemical Science
Experimental study
Not applicable
“Synthesis of bacteriochlorophyll a”
10-Apr-2026
The authors declare no competing financial interest.