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Nevonen DE, Atoyebi AO, Luciano MP, Brückner C, Nemykin VN. Electronic Structures of an Annulated meso-Tetraphenylchlorin and a Related Chlorin Analogue Incorporating an 8-Membered Ring through MCD Spectroscopy and DFT Calculations. J Phys Chem A 2024; 128:4823-4829. [PMID: 38857383 DOI: 10.1021/acs.jpca.4c02803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Herein, we compare the electronic structures of the metal-free and nickel(II) derivatives of an annulated meso-tetraphenyldihydroxychlorin with those of the (metallo)chlorin analogues derived by pyrroline β,β'-ring cleavage of the annulated (metallo)chlorins. These (metallo)chlorin analogues incorporate 8-membered heterocycles in place of the pyrroline, carry oxo-functionalities on the former pyrroline β-carbon atoms, and were previously shown to possess drastically ruffled (twisted) nonplanar conformations. The magnetic circular dichroism spectra of all chromophores investigated feature chlorin-like UV-vis spectra and correspondingly reversed (positive-to-negative in ascending energy) sign sequences in the Q-band region, indicative of ΔHOMO < ΔLUMO relationships. Density functional theory (DFT) calculations indicate that the HOMOs in all compounds are a1u-type molecular orbitals (in traditional for the porphyrin spectroscopy D4h point group). Time-dependent DFT calculations correlate well with the experimental spectra and indicate that Gouterman's four-orbital model can be applied to these chromophores. This work highlights to which degree synthetic chlorin analogues can deviate from the structural parameters of natural chlorins without losing their electronic chlorin characteristics.
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Affiliation(s)
- Dustin E Nevonen
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Adewole O Atoyebi
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Michael P Luciano
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Christian Brückner
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Victor N Nemykin
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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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: 20] [Impact Index Per Article: 10.0] [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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Xu Q, Zhang R, Zhang H, Jin GQ, Wang BW, Zhu M, Zhang J, Gao S, Zhang JL. Porpholactam-cinnamaldehyde conjugates for promoting ROS generation in photodynamic therapy. J PORPHYR PHTHALOCYA 2021. [DOI: 10.1142/s1088424621501054] [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
Photodynamic therapy (PDT) is a non-invasive method for cancer treatment that relies on the generation of excess reactive oxygen species (ROS), upon excitation of photosensitizer (PS), to eradicate tumor cells. However, the overexpress of endogenous antioxidants in tumor cells will eliminate the ROS and restrict the therapeutic efficacy of PDT. Herein, a novel type of PS was developed by conjugating cinnamaldehyde (CA), a kind of oxidative stress amplified agent, with porpholactam through a hydrazone bond. The new PS retains the photophysical properties of porpholactam, which displays high singlet oxygen quantum yield for the PDT function. The results of in vitro experiments performed including ROS assay and the cytotoxicity in cancer cells suggest that the rational design of the novel porpholactam-CA derivatives result in enhanced ROS generation upon irradiation, providing a possible approach to achieve enhanced therapeutic effects in PDT.
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Affiliation(s)
- Qifan Xu
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruijing Zhang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, China
| | - Hang Zhang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Guo-Qing Jin
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Bing-Wu Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Chemistry and Chemical Engineering, Guangdong Laboratory, Shantou 515031, China
| | - Mengliang Zhu
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jing Zhang
- Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Song Gao
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, China
- Chemistry and Chemical Engineering, Guangdong Laboratory, Shantou 515031, China
| | - Jun-Long Zhang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Chemistry and Chemical Engineering, Guangdong Laboratory, Shantou 515031, China
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Luciano MP, Atoyebi AO, Tardie W, Zeller M, Brückner C. Pyrrole-Modified Porphyrins Containing Eight-Membered Heterocycles Using a Reversal of the "Breaking and Mending" Strategy. J Org Chem 2020; 85:15273-15286. [PMID: 33174754 DOI: 10.1021/acs.joc.0c02108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conversion of meso-aryl-porphyrins/chlorins to porphyrinoids containing nonpyrrolic heterocycles (so-called pyrrole-modified porphyrins, PMPs) along an approach we dubbed "the breaking and mending of porphyrins" is well known. However, examples are limited to the synthesis of PMPs containing up to six-membered heterocycles; the syntheses of larger rings failed. We report here hitherto unavailable eight-membered chlorin-type PMPs using an inverted "mending and breaking" approach. All examples are based on the addition of N,N'-dimethylurea derivatives to a meso-phenyl-β,β'-dioxoporphyrin, followed by oxidative cleavage of the intermediate diol adduct. We correlate the extremely nonplanar solid-state structures of three crystallographically characterized PMPs containing an eight-membered ring with their solution-state optical properties. The first examples of bis-modified, bacteriochlorin-type PMPs containing either two eight-membered rings or an eight-membered ring and an imidazolone ring are also detailed. Using other N,N'-nucleophiles failed to either generate chlorins containing a β,β'-dihydroxypyrroline, a prerequisite for the "breaking step," or the cleavage of those substrates that did generate a diol underwent subsequent reactions that thwarted the generation of the desired PMPs. This contribution adds novel PMPs containing eight-membered rings, highlights the effects these derivatizations have on the macrocycle conformation, and how that affects their optical properties.
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Affiliation(s)
- Michael P Luciano
- Department of Chemistry, University of Connecticut, Unit 3060, Storrs, Connecticut 06269-3060, United States
| | - Adewole O Atoyebi
- Department of Chemistry, University of Connecticut, Unit 3060, Storrs, Connecticut 06269-3060, United States
| | - Weston Tardie
- Department of Chemistry, University of Connecticut, Unit 3060, 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, University of Connecticut, Unit 3060, Storrs, Connecticut 06269-3060, United States
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Thuita D, Damunupola D, Brückner C. Oxazolochlorins 21. Most Efficient Access to meso-Tetraphenyl- and meso-Tetrakis(pentafluorophenyl)porpholactones, and Their Zinc(II) and Platinum(II) Complexes. Molecules 2020; 25:E4351. [PMID: 32972021 PMCID: PMC7570530 DOI: 10.3390/molecules25184351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/12/2020] [Accepted: 09/16/2020] [Indexed: 01/28/2023] Open
Abstract
meso-Phenyl- and meso-pentafluorophenyl-porpholactones, their metal complexes, as well as porphyrinoids directly derived from them are useful in a number of technical and biomedical applications, and more uses are expected to be discovered. About a dozen competing and complementary pathways toward their synthesis were reported. The suitability of the methods changes with the meso-aryl group and whether the free base or metal derivatives are sought. These circumstances make it hard for anyone outside of the field of synthetic porphyrin chemistry to ascertain which pathway is the best to produce which specific derivative. We report here on what we experimentally evaluated to be the most efficient pathways to generate the six key compounds from the commercially available porphyrins, meso-tetraphenylporphyrin (TPP) and meso-tetrakis(pentafluorophenyl)porphyrin (TFPP): free base meso-tetraphenylporpholactone (TPL) and meso-tetrakis(pentafluorophenyl)porpholactone (TFPL), and their platinum(II) and zinc(II) complexes TPLPt, TFPLPt, TPLZn, and TFPLZn, respectively. Detailed procedures are provided to make these intriguing molecules more readily available for their further study.
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Affiliation(s)
| | | | - Christian Brückner
- Department of Chemistry, University of Connecticut, Unit 3060, Storrs, CT 06269–3060, USA; (D.T.); (D.D.)
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Ning Y, Jin GQ, Zhang JL. Porpholactone Chemistry: An Emerging Approach to Bioinspired Photosensitizers with Tunable Near-Infrared Photophysical Properties. Acc Chem Res 2019; 52:2620-2633. [PMID: 31298833 DOI: 10.1021/acs.accounts.9b00119] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chlorophylls, known as the key building blocks of natural light-harvesting antennae, are essential to utilize solar energy from visible to near-infrared (NIR) region during the photosynthesis process. The fundamental studies for the relationship between structure and photophysical properties of chlorophylls disclosed the importance of β-peripheral modification and thus boosted the fast growth of NIR absorbing/emissive porphyrinoids via altering the extent of π-conjugation and the degree of distortion from the planarity of macrocycle. Despite the tremendous progress made in various porphyrin-based synthetic models, it still remains a challenge to precisely modulate photophysical properties through fine-tuning of β-peripheral structures in the way natural chlorophylls do. With this in mind, we initiated a program and focused on meso-C6F5-substituted porpholactone (F20TPPL), in which one β-pyrrolic double bond was replaced by a lactone moiety, as an attractive platform to construct the bioinspired library of NIR porphyrinoids. In this Account, we summarize our recent contributions to the bioinspired design, synthesis, photophysical characterization, and applications of porpholactones and their derivatives. We have developed a general, convenient method to directly prepare porpholactones in large scale up to gram, which forms the chemical basis of porpholactone chemistry. By modulation of the saturation level and in particular regioisomerization of β-dilactone moieties, a synthetic library constituted by a series of porpholactones and their derivatives has been established. Thanks to the electron-withdrawing nature of lactone moiety, derivation of the saturation levels gives help to build stable models for chlorin, bacteriochlorin, and tunichlorin. It is worth noting that regioisomerization of dilactone moieties mimics the relative orientation of β-substituents in natural chlorophylls and hemes, which was considered as the key factor to tune NIR absorption and reactivity. Porpholactones can illustrate the capability of fine-tuning photophysical properties including the excited triplet states by subtle alteration of β-peripheral structures in the presence of transition metals and lanthanides (Ln). Furthermore, they can serve as efficient photosensitizers for singlet oxygen and NIR Ln, showing potential applications in cell imaging and photocytotoxicity studies. The high luminescence, tunable structures, high cellular uptake, and intense NIR absorption render them as promising and competitive candidates for theranostics in vitro and in vivo. Therefore, extending the studies of "porpholactone chemistry" not only tests the fundamental understanding of the structure-function relationship that governs NIR photophysical properties of natural tetrapyrrole cofactors such as chlorophylls but also provides the guiding principles for the bioinspired design of NIR luminescent molecular probes with various applications. Taken together, as a new synthetic porphyrin derivative, porpholactone chemistry shines light on synthetic porphyrin, bioinorganic, and lanthanide chemistry.
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Affiliation(s)
- Yingying Ning
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Guo-Qing Jin
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Jun-Long Zhang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
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