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Rodriguez LE, Weber JM, Barge LM. Evaluating Pigments as a Biosignature: Abiotic/Prebiotic Synthesis of Pigments and Pigment Mimics in Planetary Environments. ASTROBIOLOGY 2024; 24:767-782. [PMID: 38768415 DOI: 10.1089/ast.2023.0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Pigments serve a multitude of functions in biology including light harvesting for photosynthesis, radiation protection, membrane support, and defense. The ubiquity of pigments-especially within extremophiles found in high-radiation, high-salinity, and dry environments-and their detectability via mission-ready techniques have elevated these molecules as promising targets in the search for evidence of life elsewhere. Moreover, the detection of pigments has been proposed as a "smoking gun" for extraterrestrial life as it has been suggested that these molecules cannot be generated abiotically. However, while pigments may hold promise as a biosignature, current understanding of their possible prebiotic origins remains understudied and uncertain. Better understanding of the abiotic synthesis of pigments is critical for evaluating the biogenicity of any pigment detected during missions, including by the Mars Perseverance rover or from returned samples. Compounding this uncertainty is the broad definition of pigment as it includes any compound capable of absorbing visible light and by itself does not specify a particular chemical motif. While not experimentally verified, there are promising prebiotic routes for generating pigments including hemes, chlorophylls, and carotenoids. Herein, we review the biochemistry of pigments, the inherent assumptions made when searching for these molecules in the field, their abiotic synthesis in industry and prebiotic reactions, prebiotically relevant molecules that can mimic their spectral signatures, and implications/recommendations for future work.
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Affiliation(s)
- Laura E Rodriguez
- Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas, USA
| | - Jessica M Weber
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Laura M Barge
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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Aicher D, Damunupola D, Stark CBW, Wiehe A, Brückner C. meso-Tetrahexyl-7,8-dihydroxychlorin and Its Conversion to ß-Modified Derivatives. Molecules 2024; 29:2144. [PMID: 38731635 PMCID: PMC11085094 DOI: 10.3390/molecules29092144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 05/13/2024] Open
Abstract
meso-Tetrahexylporphyrin was converted to its corresponding 7,8-dihydroxychlorin using an osmium tetroxide-mediated dihydroxylation strategy. Its diol moiety was shown to be able to undergo a number of subsequent oxidation reactions to form a chlorin dione and porpholactone, the first meso-alkylporphyrin-based porphyrinoid containing a non-pyrrolic building block. Further, the diol chlorin was shown to be susceptible to dehydration, forming the porphyrin enol that is in equilibrium with its keto-chlorin form. The meso-hexylchlorin dione could be reduced and it underwent mono- and bis-methylation reactions using methyl-Grignard reagents, and trifluoromethylation using the Ruppert-Prakash reagent. The optical and spectroscopic properties of the products are discussed and contrasted to their corresponding meso-aryl derivatives (where known). This contribution establishes meso-tetrahexyl-7,8-dihydroxychlorins as a new and versatile class of chlorins that is susceptible to a broad range of conversions to generate functionalized chlorins and a pyrrole-modified chlorin analogue.
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Affiliation(s)
- Daniel Aicher
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Dinusha Damunupola
- Department of Chemistry, University of Connecticut, 55 N Eagleville Rd., Storrs, CT 06269-3060, USA
| | - Christian B. W. Stark
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Arno Wiehe
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, 55 N Eagleville Rd., Storrs, CT 06269-3060, USA
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Govindjee G, Stirbet A, Lindsey JS, Scheer H. On the Pelletier and Caventou (1817, 1818) papers on chlorophyll and beyond. PHOTOSYNTHESIS RESEARCH 2024; 160:55-60. [PMID: 38488941 DOI: 10.1007/s11120-024-01081-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 01/27/2024] [Indexed: 03/17/2024]
Abstract
The first use of the word 'chlorophyll' (chlorophile or chlorophyle in the French original) appeared in two papers by Pierre-Joseph Pelletier and Joseph Bienaimé Caventou, pharmacists in Paris who isolated and studied the green pigment from plants. Here, we provide English translations of their 1818 note and the slightly longer 1817 paper. Historical context is provided including a timeline of key discoveries in chlorophyll chemistry pertaining to photosynthesis.
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Affiliation(s)
- Govindjee Govindjee
- Department of Plant Biology, Department of Biochemistry and Center of Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | | | - Jonathan S Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, NC, USA
| | - Hugo Scheer
- Department of Biology 1-Botany, Ludwig-Maximilians-University, 80638, Munich, Germany
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Bhattacharya S, Nevonen DE, Auty AJ, Graf A, Appleby M, Chaudhri N, Chekulaev D, Brückner C, Chauvet AAP, Nemykin VN. Photophysical Exploration of Two Isomers of Octaethyltrioxopyrrocorphin. J Phys Chem A 2023; 127:7694-7706. [PMID: 37690121 DOI: 10.1021/acs.jpca.3c03184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The introduction of three β-oxosubstituents to octaethylporphyrin by means of an oxidation/rearrangement reaction generates the trioxopyrrocorphin chromophore. Pyrrocorphins (hexahydroporphyrins) are generally nonaromatic, but we recently demonstrated trioxopyrrocorphins to possess considerable aromatic character. This contribution explores the photophysical characteristics of these unusual chromophores. In agreement with density functional theory modeling, the UV-vis and magnetic circular dichroism spectra of the two─out of the four possible─triketone regioisomers investigated conform to the Gouterman model of porphyrinoid optical spectra, in alignment with their aromaticity. Their excited-state dynamics shed further light on the degree to which β-oxo substitutions tune the photophysical properties of porphyrinoids. Introduction of β-oxo functionalities increases the rate and yield of intersystem crossing and shortens the triplet state lifetime. Unexpectedly, the singlet oxygen generation yield of both pyrrocorphins remains relatively high, with modes of distortion from planarity likely enhancing triplet energy transfer. This work thus expands our understanding of a rare class of porphyrinoids and further characterizes them as sustaining aromatic porphyrinic π-systems. Our findings suggest triple β-oxo substitution as a viable route toward the development of novel, high-singlet oxygen yield porphyrinic photosensitizers.
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Affiliation(s)
- Sayantan Bhattacharya
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, U.K
| | - Dustin E Nevonen
- Department of Chemistry, University of Tennessee, 1420 Circle Dr., Knoxville, Tennessee 37996-1600, United States
| | - Alexander J Auty
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, U.K
| | - Arthur Graf
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, U.K
| | - Martin Appleby
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, U.K
| | - Nivedita Chaudhri
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Dimitri Chekulaev
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, U.K
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Adrien A P Chauvet
- Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, U.K
| | - Victor N Nemykin
- Department of Chemistry, University of Tennessee, 1420 Circle Dr., Knoxville, Tennessee 37996-1600, United States
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Nguyen KU, Zhang Y, Liu Q, Zhang R, Jin X, Taniguchi M, Miller ES, Lindsey JS. Tolyporphins-Exotic Tetrapyrrole Pigments in a Cyanobacterium-A Review. Molecules 2023; 28:6132. [PMID: 37630384 PMCID: PMC10459692 DOI: 10.3390/molecules28166132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 08/27/2023] Open
Abstract
Tolyporphins were discovered some 30 years ago as part of a global search for antineoplastic compounds from cyanobacteria. To date, the culture HT-58-2, comprised of a cyanobacterium-microbial consortium, is the sole known producer of tolyporphins. Eighteen tolyporphins are now known-each is a free base tetrapyrrole macrocycle with a dioxobacteriochlorin (14), oxochlorin (3), or porphyrin (1) chromophore. Each compound displays two, three, or four open β-pyrrole positions and two, one, or zero appended C-glycoside (or -OH or -OAc) groups, respectively; the appended groups form part of a geminal disubstitution motif flanking the oxo moiety in the pyrroline ring. The distinct structures and repertoire of tolyporphins stand alone in the large pigments-of-life family. Efforts to understand the cyanobacterial origin, biosynthetic pathways, structural diversity, physiological roles, and potential pharmacological properties of tolyporphins have attracted a broad spectrum of researchers from diverse scientific areas. The identification of putative biosynthetic gene clusters in the HT-58-2 cyanobacterial genome and accompanying studies suggest a new biosynthetic paradigm in the tetrapyrrole arena. The present review provides a comprehensive treatment of the rich science concerning tolyporphins.
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Affiliation(s)
- Kathy-Uyen Nguyen
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
| | - Yunlong Zhang
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
| | - Qihui Liu
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
| | - Ran Zhang
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
| | - Xiaohe Jin
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
| | - Masahiko Taniguchi
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
| | - Eric S. Miller
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695-7612, USA;
| | - Jonathan S. Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA; (K.-U.N.); (Y.Z.); (Q.L.); (R.Z.); (X.J.); (M.T.)
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Nguyen KC, Lindsey JS. Synthesis of a BC-Dihydrodipyrrin Building Block of Bacteriochlorophyll a. J Org Chem 2023; 88:11205-11216. [PMID: 37471708 DOI: 10.1021/acs.joc.3c01216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
A strategy for the synthesis of bacteriochlorophyll a relies on joining AD and BC halves that contain the requisite stereochemical configurations of the target macrocycle. The BC half (1) is a dihydrodipyrrin bearing a dimethoxymethyl group at the 1-position, a β-ketoester at the 8-position, and (R)-2-methyl and (R)-3-ethyl substituents in the pyrroline ring. An established route to AD-dihydrodipyrrins (Pd-mediated coupling of a 2-halopyrrole with a chiral 4-pentynoic acid followed by Petasis methenylation, acidic hydrolysis, Paal-Knorr ring closure, and Riley oxidation) proved to be unviable for BC-dihydrodipyrrins given the presence of the β-ketoester unit. A route presented here entails Pd-mediated coupling of a 2-halopyrrole (2) with (3R,4R)-4-ethyl-1,1-dimethoxy-3-methylhex-5-yn-2-one (3), anti-Markovnikov hydration of the alkyne to give the 1,4-diketone, and Paal-Knorr ring closure. Compound 3 was prepared by Schreiber-modified Nicholas reaction beginning with (S)-4-isopropyl-3-propionyloxazolidin-2-one and the hexacarbonyldicobalt complex of (±) 3-methoxy-1-(trimethylsilyl)pentyne followed by transformation of the aldehyde derived therefrom to the 1,1-dimethoxymethylcarbonyl motif. The absolute stereochemical configuration of the Schreiber-Nicholas alkylation product was confirmed by single-crystal X-ray diffraction, whereas the BC half (1) by 1H NMR spectroscopy showed a J value of 2.9 Hz consistent with the trans-configuration. Taken together, the route provides a key chiral building block for the synthesis of photosynthetic tetrapyrroles and analogues.
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Affiliation(s)
- Khiem Chau Nguyen
- Department of Chemistry North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jonathan S Lindsey
- Department of Chemistry North Carolina State University, Raleigh, North Carolina 27695, United States
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Taniguchi M, Lindsey JS. Absorption and Fluorescence Spectra of Open-chain Tetrapyrrole Pigments–Bilirubins, Biliverdins, Phycobilins, and Synthetic Analogues. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2023. [DOI: 10.1016/j.jphotochemrev.2023.100585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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8
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Chau Nguyen K, Nguyen Tran AT, Wang P, Zhang S, Wu Z, Taniguchi M, Lindsey JS. Four Routes to 3-(3-Methoxy-1,3-dioxopropyl)pyrrole, a Core Motif of Rings C and E in Photosynthetic Tetrapyrroles. Molecules 2023; 28:molecules28031323. [PMID: 36770988 PMCID: PMC9920783 DOI: 10.3390/molecules28031323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 01/23/2023] [Indexed: 02/03/2023] Open
Abstract
The photosynthetic tetrapyrroles share a common structural feature comprised of a β-ketoester motif embedded in an exocyclic ring (ring E). As part of a total synthesis program aimed at preparing native structures and analogues, 3-(3-methoxy-1,3-dioxopropyl)pyrrole was sought. The pyrrole is a precursor to analogues of ring C and the external framework of ring E. Four routes were developed. Routes 1-3 entail a Pd-mediated coupling process of a 3-iodopyrrole with potassium methyl malonate, whereas route 4 relies on electrophilic substitution of TIPS-pyrrole with methyl malonyl chloride. Together, the four routes afford considerable latitude. A long-term objective is to gain the capacity to create chlorophylls and bacteriochlorophylls and analogues thereof by facile de novo means for diverse studies across the photosynthetic sciences.
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Lalisse RF, Hadad CM, Brückner C, Guberman-Pfeffer MJ. [3 + 2]-Cycloadditions with Porphyrin β,β'-Bonds: Theoretical Basis of the Counterintuitive meso-Aryl Group Influence on the Rates of Reaction. J Org Chem 2022; 87:16473-16482. [PMID: 36444511 DOI: 10.1021/acs.joc.2c02192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Removal of a β,β'-bond from meso-tetraarylporphyrin using [3 + 2]-cycloadditions generates meso-tetraarylhydroporphyrins. Literature evidence indicates that meso-tetraphenylporphyrins react more sluggishly with 1,3-dipoles such as ylides and OsO4 (in the presence of pyridine) than meso-tetrakis(pentafluorophenyl)porphyrin. The trend is counterintuitive for the reaction with OsO4, as this formal oxidation reaction is expected to proceed more readily with more electron-rich substrates. This work presents a density functional theory-based computational study of the frontier molecular orbital (FMO) interactions and reaction profile thermodynamics involved in the reaction of archetypical cycloaddition reactions (a simple ylide, OsO4, OsO4·py, OsO4·(py)2, and ozone) with the β,β'-double bonds of variously fluorinated meso-arylporphyrins. The trend observed for the Type I cycloaddition of an ylide is straightforward, as lowering the LUMO of the porphyrin with increasing meso-phenyl-fluorination also lowers the reaction barrier. The corresponding simple FMO analyses of Type III cycloadditions do not correctly model the reaction energetics. This is because increasing fluorination leads to lowering of the porphyrin HOMO-2, thus increasing the reaction barrier. However, coordination of pyridine to OsO4 preorganizes the transition state complex; lowering of the energy barrier by the preorganization exceeds the increase in repulsive orbital interactions, overall accelerating the cycloaddition and rationalizing the counterintuitive experimental findings.
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Affiliation(s)
- Remy F Lalisse
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, United States
| | - Christopher M Hadad
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, United States
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, Unit 3060, Storrs, Connecticut 06269-3060, United States
| | - Matthew J Guberman-Pfeffer
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar St., New Haven, Connecticut 06510, United States.,Microbial Sciences Institute, Yale University, 840 West Campus Drive, West Haven, Connecticut 06516, United States
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Hirose M, Tsukatani Y, Harada J, Tamiaki H. Characterization of regioisomeric diterpenoid tails in bacteriochlorophylls produced by geranylgeranyl reductase from Halorhodospira halochloris and Blastochloris viridis. PHOTOSYNTHESIS RESEARCH 2022; 154:1-12. [PMID: 35852706 DOI: 10.1007/s11120-022-00938-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Geranylgeranyl reductase (GGR) encoded by the bchP gene catalyzes the reductions of three unsaturated C = C double bonds (C6 = C7, C10 = C11, and C14 = C15) in a geranylgeranyl (GG) group of the esterifying moiety in 17-propionate residue of bacteriochlorophyll (BChl) molecules. It was recently reported that GGR in Halorhodospira halochloris potentially catalyzes two hydrogenations, yielding BChl with a tetrahydrogeranylgeranyl (THGG) tail. Furthermore, its engineered GGR, in which N-terminal insertion peptides characteristic for H. halochloris were deleted, performed single hydrogenation, producing BChl with a dihydrogeranylgeranyl (DHGG) tail. In some of these enzymatic reactions, it remained unclear in which order the C = C double bond in a GG group was first reduced. In this study, we demonstrated that the (variant) GGR from H. halochloris catalyzed an initial reduction of the C6 = C7 double bond to yield a 6,7-DHGG tail. The intact GGR of H. halochloris catalyzed the further hydrogenation of the C14 = C15 double bonds to give a 6,7,14,15-THGG group, whereas deleting the characteristic peptide region from the GGR suppressed the C14 = C15 reduction. We also verified that in a model bacterium, Blastochloris viridis producing standard BChl-b, the reduction of a GG to phytyl group occurred via 10,11-DHGG and 6,7,10,11-THGG. The high-performance liquid chromatographic elution profiles of BChls-a/b employed in this study are essential for identifying the regioisomeric diterpenoid tails in the BChls of phototrophic bacteria distributed in nature and elucidating GGR enzymatic reactions.
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Affiliation(s)
- Mitsuaki Hirose
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Yusuke Tsukatani
- Institute for Extra-Cutting-Edge Science and Technology Avant-Garde Research (X-Star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, 237-0061, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
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Taniguchi M, Bocian DF, Holten D, Lindsey JS. Beyond green with synthetic chlorophylls – Connecting structural features with spectral properties. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2022. [DOI: 10.1016/j.jphotochemrev.2022.100513] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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Phenylene-linked tetrapyrrole arrays containing free base and diverse metal chelate forms – Versatile synthetic architectures for catalysis and artificial photosynthesis. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214278] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Chaudhri N, Brückner C, Zeller M. Crystal structure of cis-7,8-dihy-droxy-5,10,15,20-tetra-phenyl-chlorin and its zinc(II)-ethyl-enedi-amine complex. Acta Crystallogr E Crystallogr Commun 2022; 78:392-398. [PMID: 35492263 PMCID: PMC8983991 DOI: 10.1107/s2056989022002729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/10/2022] [Indexed: 11/30/2022]
Abstract
The title chlorin, 2PhH2 , hydrogen-bonded to di-methyl-amino-pyridine (DMAP), C44H32N4O2·C7H10N2, and its corresponding zinc(II) complex, 2PhZn, axially coordinated to ethyl-enedi-amine (EDA), [Zn(C44H30N4O2)]·C2H8N2, were isolated and crystallized by adventitious reduction of the corresponding osmate esters by DMAP and EDA, respectively. Known since 1996 and, inter alia, used for the preparation of a wide range of (planar and non-planar) chlorin analogues (so-called pyrrole-modified porphyrins), their conformational analyses in the solid state are important benchmarks. Both macrocycles are only modestly distorted from planarity and both are slightly more non-planar than the corresponding dimeth-oxy-derivative, but less planar than a free-base meso-penta-fluoro-phenyl-based osmate ester. NSD analyses provide qu-anti-tative and qualitative analyses of the distortion modes. One origin of the non-planarity is presumably the avoidance of the eclipsed configuration of the two vic-cis diols on the pyrroline moiety; the resulting deformation of the pyrroline translates in some cases into the macrocycle. The structure of 2PhH2 features voids making up ca 26% of the unit-cell volume filled with highly disordered solvate mol-ecules (chloro-form and hexa-nes). 2PhZn crystallized with a 13.6 (4)% occupied solvate methanol mol-ecule.
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Affiliation(s)
- Nivedita Chaudhri
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, USA
| | - Matthias Zeller
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
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Thuita DW, Brückner C. Metal Complexes of Porphyrinoids Containing Nonpyrrolic Heterocycles. Chem Rev 2022; 122:7990-8052. [PMID: 35302354 DOI: 10.1021/acs.chemrev.1c00694] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The replacement of one or more pyrrolic building block(s) of a porphyrin by a nonpyrrolic heterocycle leads to the formation of so-called pyrrole-modified porphyrins (PMPs), porphyrinoids of broad structural variability. The wide range of coordination environments (type, number, charge, and architecture of the donor atoms) that the pyrrole-modified frameworks provide to the central metal ions, the frequent presence of donor atoms at their periphery, and their often observed nonplanarity or conformational flexibility distinguish the complexes of the PMPs clearly from those of the traditional square-planar, dianionic, N4-coordinating (hydro)porphyrins. Their different coordination properties suggest their utilization in areas beyond which regular metalloporphyrins are suitable. Following a general introduction to the synthetic methodologies available to generate pyrrole-modified porphyrins, their general structure, history, coordination chemistry, and optical properties, this Review highlights the chemical, electronic (optical), and structural differences of specific classes of metalloporphyrinoids containing nonpyrrolic heterocycles. The focus is on macrocycles with similar "tetrapyrrolic" architectures as porphyrins, thusly excluding the majority of expanded porphyrins. We highlight the relevance and application of these metal complexes in biological and technical fields as chemosensors, catalysts, photochemotherapeutics, or imaging agents. This Review provides an introduction to the field of metallo-PMPs as well as a comprehensive snapshot of the current state of the art of their synthesis, structures, and properties. It also aims to provide encouragement for the further study of these intriguing and structurally versatile metalloporphyrinoids.
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Affiliation(s)
- Damaris Waiyigo Thuita
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
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Abstract
Chlorophylls provide the basis for photosynthesis and thereby most life on Earth. Besides their involvement in primary charge separation in the reaction center, they serve as light-harvesting and light-sensing pigments, they also have additional functions, e.g., in inter-system electron transfer. Chlorophylls also have a wealth of applications in basic science, medicine, as colorants and, possibly, in optoelectronics. Considering that there has been more than 200 years of chlorophyll research, one would think that all has been said on these pigments. However, the opposite is true: ongoing research evidenced in this Special Issue brings together current work on chlorophylls and on their carotenoid counterparts. These introductory notes give a very brief and in part personal account of the history of chlorophyll research and applications, before concluding with a snapshot of this year's publications.
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Affiliation(s)
- Hugo Scheer
- Bereich Systematik, Biodiversität und Evolution der Pflanzen, Universität München, Menzinger Str. 67, 80638 München, Germany
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16
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Jing H, Wang P, Chen B, Jiang J, Vairaprakash P, Liu S, Rong J, Chen CY, Nalaoh P, Lindsey JS. Synthesis of bacteriochlorins bearing diverse β-substituents. NEW J CHEM 2022. [DOI: 10.1039/d1nj05852e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Eleven bacteriochlorins have been prepared for surface attachment, bioconjugation, water-solubilization, vibrational studies, and elaboration into multichromophore arrays.
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Affiliation(s)
- Haoyu Jing
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Pengzhi Wang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Boyang Chen
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Jianbing Jiang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Pothiappan Vairaprakash
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Sijia Liu
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Jie Rong
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Chih-Yuan Chen
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Phattananawee Nalaoh
- Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong, 21210, Thailand
| | - Jonathan S. Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
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17
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Jing H, Liu S, Jiang J, Tran VP, Rong J, Wang P, Lindsey JS. Meso bromination and derivatization of synthetic bacteriochlorins. NEW J CHEM 2022. [DOI: 10.1039/d1nj05853c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Twelve bacteriochlorin building blocks featuring meso-substitution have been prepared including a set with finely tuned long-wavelength absorption (725–757 nm) for studies in photonics.
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Affiliation(s)
- Haoyu Jing
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Sijia Liu
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Jianbing Jiang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Vy-Phuong Tran
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Jie Rong
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Pengzhi Wang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
| | - Jonathan S. Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
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18
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Brückner C, Chaudhri N, Nevonen DE, Bhattacharya S, Graf A, Kaesmann E, Li R, Guberman-Pfeffer MJ, Mani T, Nimthong-Roldán A, Zeller M, Chauvet AAP, Nemykin V. Structural and Photophysical Characterization of All Five Constitutional Isomers of the Octaethyl-β,β'-dioxo-bacterio- and -isobacteriochlorin Series. Chemistry 2021; 27:16189-16203. [PMID: 34535932 DOI: 10.1002/chem.202103014] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Indexed: 11/11/2022]
Abstract
It is well-known that treatment of β-octaethylporphyrin with H2 O2 /conc. H2 SO4 converts it to a β-oxochlorin as well as all five constitutional isomers of the corresponding β,β'-dioxo-derivatives: two bacteriochlorin-type isomers (β-oxo groups at opposite pyrrolic building blocks) and three isobacteriochlorin-type isomers (β-oxo-groups at adjacent pyrrolic building blocks). By virtue of the presence of the strongly electronically coupled β-oxo auxochromes, none of the chromophores are archetypical chlorins, bacteriochlorins, or isobacteriochlorins. Here the authors present, inter alia, the single crystal X-ray structures of all free-base diketone isomers and a comparative description of their UV-vis absorption spectra in neutral and acidic solutions, and fluorescence emission and singlet oxygen photosensitization properties, Magnetic Circular Dichroism (MCD) spectra, and singlet excited state lifetimes. DFT computations uncover underlying tautomeric equilibria and electronic interactions controlling their electronic properties, adding to the understanding of porphyrinoids carrying β-oxo functionalities. This comparative study lays the basis for their further study and utilization.
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Affiliation(s)
- Christian Brückner
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, United States
| | - Nivedita Chaudhri
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, United States
| | - Dustin E Nevonen
- Department of Chemistry, University of Manitoba Winnipeg, Manitoba, R3T 2 N2, Canada
| | - Sayantan Bhattacharya
- Department of Chemistry, University of Sheffield Dainton Building, Sheffield, S3 7HF, United Kingdom
| | - Arthur Graf
- Department of Chemistry, University of Sheffield Dainton Building, Sheffield, S3 7HF, United Kingdom
| | - Elizabeth Kaesmann
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, United States
| | - Ruoshi Li
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, United States
| | | | - Tomoyasu Mani
- Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060, United States
| | - Arunpatcha Nimthong-Roldán
- Department of Chemistry, Youngstown State University One University Plaza, Youngstown, OH 44555-3663, United States
| | - Matthias Zeller
- Department of Chemistry, Youngstown State University One University Plaza, Youngstown, OH 44555-3663, United States.,Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, United States
| | - Adrien A P Chauvet
- Department of Chemistry, University of Sheffield Dainton Building, Sheffield, S3 7HF, United Kingdom
| | - Victor Nemykin
- Department of Chemistry, University of Manitoba Winnipeg, Manitoba, R3T 2 N2, Canada.,Department of Chemistry, University of Tennessee, 552 Buehler Hall, 1420 Circle Dr., Knoxville, TN, 37996-1600, United States
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19
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Sollert C, Kocsi D, Jane RT, Orthaber A, Borbas KE. C-glycosylated pyrroles and their application in dipyrromethane and porphyrin synthesis. J PORPHYR PHTHALOCYA 2021. [DOI: 10.1142/s1088424621500723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pyrrole C-glycosylated in either the 2- or the 3-position could be prepared by the acid-catalyzed reaction between trichloroacetimidate glycosyl donors and pyrrole, or [Formula: see text]-phenyl-tri?uoroacetimidate glucosyl donor and [Formula: see text]-TIPS pyrrole, respectively. Pyrroles carrying glucose, mannose, galactose and lactose in the 2-position, and glucose in the 3-position were obtained. The configurations of the products could be assigned using a combination of 1D and 2D NMR spectroscopy. A number of undesired background reactions yielding a variety of stereo- and regioisomers were identified; in several cases these could be eliminated. Glycosylpyrroles could be incorporated into mono- and diglycosylated dipyrromethanes, a diglycosylated BODIPY dye, and a monoglycosylated Zn(II) porphyrin without damaging the sugar unit.
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Affiliation(s)
- Carina Sollert
- Department of Chemistry, Ångström Laboratory, Box 523, Uppsala University, 75120 Uppsala, Sweden
| | - Daniel Kocsi
- Department of Chemistry, Ångström Laboratory, Box 523, Uppsala University, 75120 Uppsala, Sweden
| | - Reuben T. Jane
- Department of Chemistry, Ångström Laboratory, Box 523, Uppsala University, 75120 Uppsala, Sweden
| | - Andreas Orthaber
- Department of Chemistry, Ångström Laboratory, Box 523, Uppsala University, 75120 Uppsala, Sweden
| | - K. Eszter Borbas
- Department of Chemistry, Ångström Laboratory, Box 523, Uppsala University, 75120 Uppsala, Sweden
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20
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A Review of Bacteriochlorophyllides: Chemical Structures and Applications. Molecules 2021; 26:molecules26051293. [PMID: 33673610 PMCID: PMC7957641 DOI: 10.3390/molecules26051293] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/23/2021] [Accepted: 02/23/2021] [Indexed: 01/08/2023] Open
Abstract
Generally, bacteriochlorophyllides were responsible for the photosynthesis in bacteria. Seven types of bacteriochlorophyllides have been disclosed. Bacteriochlorophyllides a/b/g could be synthesized from divinyl chlorophyllide a. The other bacteriochlorophyllides c/d/e/f could be synthesized from chlorophyllide a. The chemical structure and synthetic route of bacteriochlorophyllides were summarized in this review. Furthermore, the potential applications of bacteriochlorophyllides in photosensitizers, immunosensors, influence on bacteriochlorophyll aggregation, dye-sensitized solar cell, heme synthesis and for light energy harvesting simulation were discussed.
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21
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Senge MO, Sergeeva NN, Hale KJ. Classic highlights in porphyrin and porphyrinoid total synthesis and biosynthesis. Chem Soc Rev 2021; 50:4730-4789. [PMID: 33623938 DOI: 10.1039/c7cs00719a] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Porphyrins feature prominently in nature, be it as enzymatic cofactors, electron and exciton shuffles, as photoactive dyes, or as signaling substances. Their involvement in the generation, storage and use of oxygen is pivotal to life, while their photochemical properties are central to the biochemical functioning of plants. When complexed to metals, porphyrins can engage in a multitude of contemporary applications ranging from solar energy generation to serving as catalysts for important chemical reactions. They are also able to function as useful theranostic agents, and as novel materials for a wide range of applications. As such, they are widely considered to be highly valuable molecules, and it almost goes without saying that synthetic organic chemistry has dramatically underpinned all the key advances made, by providing reliable access to them. In fact, strategies for the synthesis of functionalized porphyrins have now reached a state of refinement where pretty well any desired porphyrin can successfully be synthesized with the approaches that are available, including a cornucopia of related macrocycle-modified porphyrinoids. In this review, we are going to illustrate the development of this exciting field by discussing a number of classic syntheses of porphyrins. Our coverage will encompass the natural protoporphyrins and chlorophylls, while also covering general strategies for the synthesis of unsymmetrical porphyrins and chlorins. Various industrial syntheses of porphyrins will also be discussed, as will other routes of great practical importance, and avenues to key porphyrinoids with modified macrocycles. A range of selected examples of contemporary functionalization reactions will be highlighted. The various key syntheses will be described and analyzed from a traditional mechanistic organic chemistry perspective to help student readers, and those who are new to this area. The aim will be to allow readers to mechanistically appreciate and understand how many of these fascinating ring-systems are built and further functionalized.
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Affiliation(s)
- Mathias O Senge
- School of Chemistry, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin 2, Ireland.
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22
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Chung DTM, Tran PV, Chau Nguyen K, Wang P, Lindsey JS. Synthesis of model bacteriochlorophylls containing substituents of native rings A, C and E. NEW J CHEM 2021. [DOI: 10.1039/d1nj02469h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An established route to the bacteriochlorophyll skeleton from two dihydrodipyrrin halves has been extended to accommodate several substituents characteristic of the native bacteriochlorophyll a.
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Affiliation(s)
- Duy T. M. Chung
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
| | - Phuong Vy Tran
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
| | | | - Pengzhi Wang
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
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23
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Nguyen KC, Wang P, Lindsey JS. Study of conditions for streamlined assembly of a model bacteriochlorophyll from two dihydrodipyrrin halves. NEW J CHEM 2021. [DOI: 10.1039/d0nj04855k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Knoevenagel condensation followed by double-ring closure (Nazarov cyclization, electrophilic aromatic substitution, elimination of methanol) and optional zinc insertion smoothly afford models of the native bacteriochlorophylls.
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Affiliation(s)
| | - Pengzhi Wang
- Department of Chemistry North Carolina State University Raleigh
- USA
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24
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Chaudhri N, Zeller M, Brückner C. Stepwise Reduction of Octaethyl-β,β'-dioxochlorin Isomers: Access to Structurally and Electronically Diverse Hydroporphyrins. J Org Chem 2020; 85:13951-13964. [PMID: 33085480 DOI: 10.1021/acs.joc.0c01989] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Di- and tetrahydroporphyrins (chlorins, bacteriochlorins and isobacteriochlorins, respectively) are key "pigments of life." They have been a major focus of attention in synthetic tetrapyrrole chemistry. A long-known one-pot epoxidation/epoxide ring-opening/pinacol-pinacolone rearrangement of octaethylporphyrin (OEP) generates a β-ketochlorin and all five β,β'-diketone isomers. We present herein the single and double reductions of all isomers of the β,β'-diketones, generating hydroxychlorin and β-hydroxy-β-ketodihydroporphyrin isomers, generally in regioselective manner, and sets of separable stereoisomeric dihydroxytetrahydroporphyrin regioisomers. The connectivity of the regio- and stereoisomers were determined spectroscopically and, in many cases, using single-crystal X-ray crystallography. The optical properties of the chlorin-, bacteriochlorin-, and isobacteriochlorin-type chromophores are described. They highlight general observations on the regiochemical effects of the β-oxo-auxochrome. This contribution thus delineates the formation of a range of regio- and stereoisomers of a family of chromophores with broadly varying optical properties from a single and readily available starting material (OEP) in two straightforward steps, albeit requiring extensive chromatography.
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Affiliation(s)
- Nivedita Chaudhri
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Matthias Zeller
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084, United States
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
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25
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Nguyen KC, Wang P, Sommer RD, Lindsey JS. Asymmetric Synthesis of a Bacteriochlorophyll Model Compound Containing trans-Dialkyl Substituents in Ring D. J Org Chem 2020; 85:6605-6619. [DOI: 10.1021/acs.joc.0c00608] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Khiem Chau Nguyen
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Pengzhi Wang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Roger D. Sommer
- Molecular Education, Technology, and Research Innovation Center, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Jonathan S. Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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26
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Schnable D, Chaudhri N, Li R, Zeller M, Brückner C. Evaluation of Octaethyl-7,17-dioxobacteriochlorin as a Ligand for Transition Metals. Inorg Chem 2020; 59:2870-2880. [DOI: 10.1021/acs.inorgchem.9b03231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- David Schnable
- Department of Chemistry, Unit 3060, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Nivedita Chaudhri
- Department of Chemistry, Unit 3060, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Ruoshi Li
- Department of Chemistry, Unit 3060, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Matthias Zeller
- Department of Chemistry, Purdue University, 101 Wetherill Hall, 560 Oval Drive, West Lafayette, Indiana 47907-2084, United States
| | - Christian Brückner
- Department of Chemistry, Unit 3060, University of Connecticut, Storrs, Connecticut 06269-3060, United States
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27
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Noboa MA, AbuSalim DI, Lash TD. Azulichlorins and Benzocarbachlorins Derived Therefrom. J Org Chem 2019; 84:11649-11664. [PMID: 31429281 DOI: 10.1021/acs.joc.9b01578] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Acid-catalyzed condensation of azulidipyrrane aldehydes with a dihydrodipyrrin carbaldehyde afforded the first examples of azulichlorins. These macrocyclic products were isolated in a monoprotonated form, and the free bases proved to be somewhat unstable. The monocations were strongly diatropic, and proton NMR spectroscopy showed the internal C-H at ca. -2 ppm. Addition of TFA gave the related dications, but these exhibited significantly reduced aromatic ring currents. Reaction of an azulichlorin with tert-butyl hydroperoxide and KOH in dichloromethane/methanol gave a benzocarbachlorin and two related aldehydes. The UV-vis spectrum for the benzocarbachlorin showed a split Soret band at 414 and 430 nm, together with a strong chlorin-like absorption at 684 nm. The proton NMR spectrum indicated that the carbachlorin is strongly aromatic and the internal C-H was observed at -4.64 ppm. Addition of TFA afforded a C-protonated dication with a significantly increased diatropic ring current. The proton NMR spectrum, NICS calculations, and AICD plots indicated that the system favors a 22π electron delocalization pathway that runs through the fused benzo unit. Addition of TFA to the benzocarbachlorin aldehydes primarily led to the formation of monocations, and the generation of C-protonated dications was no longer favored due to the presence of electron-withdrawing formyl moieties.
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Affiliation(s)
- Mario A Noboa
- Department of Chemistry , Illinois State University , Normal , Illinois 61790-4160 , United States
| | - Deyaa I AbuSalim
- Department of Chemistry , Illinois State University , Normal , Illinois 61790-4160 , United States
| | - Timothy D Lash
- Department of Chemistry , Illinois State University , Normal , Illinois 61790-4160 , United States
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28
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Wang P, Chau Nguyen K, Lindsey JS. Synthesis of the Ring C Pyrrole of Native Chlorophylls and Bacteriochlorophylls. J Org Chem 2019; 84:11286-11293. [PMID: 31432671 DOI: 10.1021/acs.joc.9b01650] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
As part of a program to develop practical syntheses of members of the family of (bacterio)chlorophylls, two routes to 2-iodo-3-methyl-4-(3-methoxy-1,3-dioxopropyl)pyrrole, a precursor of the universal ring C, have been developed. The β-ketoester of ring C is expected to give rise to ring E upon Knoevenagel condensation and Nazarov cyclization with a ring D constituent as demonstrated in an analogue synthesis. Two viable routes were developed beginning with N-TIPS-pyrrole or with 4-oxo-2-pentene and TosMIC, affording multi-gram-quantities of this ostensibly simple pyrrole.
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Affiliation(s)
- Pengzhi Wang
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
| | - Khiem Chau Nguyen
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
| | - Jonathan S Lindsey
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
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29
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Galli U, Hysenlika R, Meneghetti F, Del Grosso E, Pelliccia S, Novellino E, Giustiniano M, Tron GC. Exploiting the Nucleophilicity of the Nitrogen Atom of Imidazoles: One-Pot Three-Component Synthesis of Imidazo-Pyrazines. Molecules 2019; 24:molecules24101959. [PMID: 31117306 PMCID: PMC6572241 DOI: 10.3390/molecules24101959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 05/16/2019] [Accepted: 05/20/2019] [Indexed: 11/16/2022] Open
Abstract
A novel one-pot multicomponent reaction to synthesize substituted imidazopyrazines is described. In brief, 1H-(imidazol-5-yl)-N-substituted methanamines react with aldehydes and isocyanides in methanol at room temperature to give imidazopyrazine derivatives in excellent yields. The imidazole nitrogen atom was able to intercept the nascent nitrilium ion, channeling the reaction toward to the sole formation of imidazopyrazines, suppressing the competitive formation of other possible side products deriving from the reaction with the high-energy nitrilium ion. The number of examples and the variability of the nature of isocyanides, aldehydes, and amine components herein employed, witness the robustness of this novel methodology.
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Affiliation(s)
- Ubaldina Galli
- Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale "A. Avogadro", 28100 Novara, Italy.
| | - Rejdia Hysenlika
- Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale "A. Avogadro", 28100 Novara, Italy.
| | - Fiorella Meneghetti
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, 20133 Milano, Italy.
| | - Erika Del Grosso
- Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale "A. Avogadro", 28100 Novara, Italy.
| | - Sveva Pelliccia
- Dipartimento di Farmacia, Università degli Studi di Napoli "Federico II", 80131 Napoli, Italy.
| | - Ettore Novellino
- Dipartimento di Farmacia, Università degli Studi di Napoli "Federico II", 80131 Napoli, Italy.
| | - Mariateresa Giustiniano
- Dipartimento di Farmacia, Università degli Studi di Napoli "Federico II", 80131 Napoli, Italy.
| | - Gian Cesare Tron
- Dipartimento di Scienze del Farmaco, Università del Piemonte Orientale "A. Avogadro", 28100 Novara, Italy.
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