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Tatarin SV, Bezzubov SI. Synthesis, Structure, and Properties of Nontrivial Iridium(III) Complexes Based on Anthracene-Decorated Benzimidazole Ligand. Inorg Chem 2024. [PMID: 39321335 DOI: 10.1021/acs.inorgchem.4c02414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2024]
Abstract
Reactions of iridium trichloride hydrate with bulky 2-(9-anthracenyl)-1-phenyl-benzimidazole (anbi) in the presence of N-donor ligands afforded a number of unique noncyclometalated complexes, while attempts to prepare a common μ-chloro-bridged bis-cyclometalated dimer systematically gave a monocyclometalated complex cis-[Ir(C,N-anbi)(N-anbi)Cl2] instead. The obtained complexes were characterized by 1H NMR, high-resolution mass spectrometry, single-crystal and powder X-ray diffraction, UV-vis spectroscopy, and cyclic voltammetry. The noncyclometalated complexes fac-[Ir(N-anbi)(N^N)Cl3)], where N^N are 4,4'-disubstituted 2,2'-bipyridines, are octahedral and contain the anthracene and 2,2'-bipyridine units in a close cofacial arrangement. These complexes were found to be exceptionally inert to the chloride ligand exchange even in the presence of silver triflate, forming a rare trinuclear Ir-μ-Cl3-Ag-μ-Cl3-Ir structure instead. In the monocyclometalated complex, the Ir(III) ion is pentacoordinated in a rare square-pyramidal geometry, where the bulky anthracene fragment is involved in the steric shielding of the metal center. This is in line with the results of gas-phase density functional theory calculations, demonstrating that the experimentally observed structure is energetically most preferable. The monocyclometalated complex is deeply colored due to intense charge-transfer absorption bands in the range 450-650 nm with ε = 2000-5000 M-1 cm-1, superior to the noncyclometalated complexes. The synthesis, structures, and properties of the new complexes are discussed in the context of the related mono-, bis-, and noncyclometalated iridium(III) compounds.
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Affiliation(s)
- Sergei V Tatarin
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia
| | - Stanislav I Bezzubov
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia
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Müller VVL, Moreth D, Kowalski K, Kowalczyk A, Gapińska M, Kutta RJ, Nuernberger P, Schatzschneider U. Tuning The Intracellular Distribution of [3+2+1] Iridium(III) Complexes In Bacterial And Mammalian Cells By iClick Reaction With Biomolecular Carriers Functionalized With Alkynone Groups. Chemistry 2024:e202401603. [PMID: 39288294 DOI: 10.1002/chem.202401603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Indexed: 09/19/2024]
Abstract
Three iridium(III) triazolato complexes of the general formula [Ir(triazolatoR,R')(ppy)(terpy)]PF6 with ppy=2-phenylpyridine and terpy=2,2':6',2''-terpyridine were efficiently prepared by iClick reaction of [Ir(N3)(ppy)(terpy)]PF6, with alkynes and alkynones, which allowed facile introduction of biological carriers such as biotin and cholic acid. In contrast to the precursor azido complex, which decomposed upon photoexcitation on a very short time scale, the triazolato complexes were stable in solution for up to 48 h. They emit in the spectral region around 540 nm with a quantum yield of 15-35 % in aerated acetonitrile solution and exhibit low cytotoxicity with IC50 values >50 μM for most complexes in L929 and HeLa cells, demonstrating their high suitability as luminescent probes. Cell uptake studies with confocal luminescence microscopy in prokaryotic Gram-positive S. aureus and Gram-negative E. coli bacteria as well as eukaryotic mammalian L929 and HeLa cells showed significant uptake in particular of the cholic acid conjugates iridium(III) moiety and distinct intracellular distribution modulated by the nature of the peripheral functional groups that can easily be modified by the iClick reaction.
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Affiliation(s)
- Victoria V L Müller
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany
| | - Dominik Moreth
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany
| | - Konrad Kowalski
- University of Lodz, Faculty of Chemistry, Department of Organic Chemistry, Tamka 12, 91-403, Lodz, Poland
| | - Aleksandra Kowalczyk
- University of Lodz, Faculty of Biology and Environmental Protection, Department of Molecular Microbiology, Banacha 12/16, 90-237, Lodz, Poland
| | - Magdalena Gapińska
- University of Lodz, Faculty of Biology and Environmental Protection, Laboratory of Microscopic Imaging and Specialized Biological Techniques, Banacha 12/16, 90-237, Lodz, Poland
| | - Roger Jan Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ulrich Schatzschneider
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany
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Lee LCC, Lo KKW. Shining New Light on Biological Systems: Luminescent Transition Metal Complexes for Bioimaging and Biosensing Applications. Chem Rev 2024; 124:8825-9014. [PMID: 39052606 PMCID: PMC11328004 DOI: 10.1021/acs.chemrev.3c00629] [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: 07/27/2024]
Abstract
Luminescence imaging is a powerful and versatile technique for investigating cell physiology and pathology in living systems, making significant contributions to life science research and clinical diagnosis. In recent years, luminescent transition metal complexes have gained significant attention for diagnostic and therapeutic applications due to their unique photophysical and photochemical properties. In this Review, we provide a comprehensive overview of the recent development of luminescent transition metal complexes for bioimaging and biosensing applications, with a focus on transition metal centers with a d6, d8, and d10 electronic configuration. We elucidate the structure-property relationships of luminescent transition metal complexes, exploring how their structural characteristics can be manipulated to control their biological behavior such as cellular uptake, localization, biocompatibility, pharmacokinetics, and biodistribution. Furthermore, we introduce the various design strategies that leverage the interesting photophysical properties of luminescent transition metal complexes for a wide variety of biological applications, including autofluorescence-free imaging, multimodal imaging, organelle imaging, biological sensing, microenvironment monitoring, bioorthogonal labeling, bacterial imaging, and cell viability assessment. Finally, we provide insights into the challenges and perspectives of luminescent transition metal complexes for bioimaging and biosensing applications, as well as their use in disease diagnosis and treatment evaluation.
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Affiliation(s)
- Lawrence Cho-Cheung Lee
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
- Laboratory for Synthetic Chemistry and Chemical Biology Limited, Units 1503-1511, 15/F, Building 17W, Hong Kong Science Park, New Territories, Hong Kong, P. R. China
| | - Kenneth Kam-Wing Lo
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
- State Key Laboratory of Terahertz and Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P. R. China
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Liu S, Wang M, Hou T, Shen X. Unprecedented hetero-coordinated Ir(C^N) 2tmd complexes containing both five- and six-membered Ir-(C^N) rings based on phenanthrylpyridine ligands: syntheses, crystal structures and photophysical properties. Dalton Trans 2023; 52:11120-11129. [PMID: 37494113 DOI: 10.1039/d3dt01809a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
By using 2-(9-phenanthryl)pyridine (phpyr) and its derivatives as cyclometalated ligands, we synthesized a set of isomeric red-emitting complexes Ir(phpyr-R)2tmd (R = -H, -CF3, -F and -CH3, tmd = 2,2,6,6-tetramethylheptane-3,5-dione) with different coordinated modes, including bis-five-membered and five- + six-membered Ir-(C^N) ring chelating modes. The latter are the first examples of hetero-coordinated Ir(C^N)2(L^X)-type complexes containing both five- and six-membered Ir-(C^N) metallocycles. Their coordination geometries were distinctly determined using X-ray crystallographic analysis. Compared to typical bis-five-membered ring-chelated complexes, these novel hetero-coordinated isomers show bathochromic emission and lower quantum yields. On careful analysis of their electrochemical behavior and DFT calculations, it has been found that the regulatory effects of the solitary six-membered metallocycles in Ir(phpyr-R)2tmd could not only stabilize the LUMO but also destabilize the HOMO, leading to a narrower energy gap. More importantly, DFT calculations of the relative energies of these isomeric complexes demonstrated that bis-five-membered and five- + six-membered chelating modes are more stable compared to bis-six-membered rings, consistent with experiments. This work provides guidance for the structural design of Ir(C^N)2(L^X)-type complexes.
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Affiliation(s)
- Sen Liu
- State Key Laboratory of Materials-oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, P. R. China.
- Zhangjiagang Institute of Nanjing Tech University, Suzhou 215600, P. R. China
| | - Mengyun Wang
- State Key Laboratory of Materials-oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, P. R. China.
| | - Tianjiao Hou
- State Key Laboratory of Materials-oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, P. R. China.
- Jiangsu Academy of Chemical Inherent Safety, Nanjing210009, P. R. China
| | - Xuan Shen
- State Key Laboratory of Materials-oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, P. R. China.
- Zhangjiagang Institute of Nanjing Tech University, Suzhou 215600, P. R. China
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Tatarin SV, Smirnov DE, Taydakov IV, Metlin MT, Emets VV, Bezzubov SI. Tailoring the π-system of benzimidazole ligands towards stable light-harvesting cyclometalated iridium(III) complexes. Dalton Trans 2023; 52:6435-6450. [PMID: 37092600 DOI: 10.1039/d3dt00200d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
The synthesis, structure, optical and redox properties as well as photovoltaic studies of iridium(III) complexes with cyclometalated 2-arylbenzimidazoles decorated with various polyaromatic fragments and an ancillary aromatic β-diketone are reported. Despite the strong preference of the iridium(III) ion to form bis- or tris-cyclometalated complexes in which the metal participates in five-membered metallacycles, the cyclometalation of the benzimidazole ligands containing rigid π-extended systems yields dimeric complexes containing strained five- or six-membered metallacycles and allows for generating an extremely rare monocyclometalated complex. X-ray crystallography shows that the steric strain observed in the dimers is retained in heteroleptic diketonate complexes which is also corroborated by gas-phase DFT calculations. While emission maxima and redox potentials of the heteroleptic complexes exhibit just a moderate variation upon the change of the cyclometalated ligands, the extension of the π-system of the benzimidazole ligands give the complexes remarkable light absorption in the visible spectral range, which meets the requirements for application in dye-sensitized solar cells. At the titania photoanodes, these iridium dyes retain their optical properties and exhibit power conversion efficiencies under standard AM 1.5 G conditions comparable to those of other iridium-based sensitizers. These results demonstrate that the size and position of the π-extended fragment in cyclometalated ligands can modulate not only the electronic structure of the corresponding iridium(III) complexes, but also affect their composition, structure and reactivity that may find implications in future design of emerging iridium dyes, emitters and catalysts.
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Affiliation(s)
- Sergei V Tatarin
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow 119991, Russia.
| | - Daniil E Smirnov
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow 119991, Russia.
| | - Ilya V Taydakov
- P.N. Lebedev Physical Institute, Russian Academy of Sciences, 53 Leninsky Prospect, Moscow 119991, Russia
| | - Mikhail T Metlin
- P.N. Lebedev Physical Institute, Russian Academy of Sciences, 53 Leninsky Prospect, Moscow 119991, Russia
- Bauman Moscow State Technical University, 2-ya Baumanskaya Str. 5/1, 105005, Moscow, Russia
| | - Victor V Emets
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow 119071, Russia
| | - Stanislav I Bezzubov
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow 119991, Russia.
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Phosphorescent Ir(III) Complexes for Biolabeling and Biosensing. Top Curr Chem (Cham) 2022; 380:35. [PMID: 35948820 DOI: 10.1007/s41061-022-00389-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 05/27/2022] [Indexed: 10/15/2022]
Abstract
Cyclometalated Ir(III) complexes exhibit strong phosphorescence emission with lifetime of submicroseconds to several microseconds at room temperature. Their synthetic versatility enables broad control of physical properties, such as charge and lipophilicity, as well as emission colors. These favorable properties have motivated the use of Ir(III) complexes in luminescent bioimaging applications. This review examines the recent progress in the development of phosphorescent biolabels and sensors based on Ir(III) complexes. It begins with a brief introduction about the basic principles of the syntheses and photophysical processes of cyclometalated Ir(III) complexes. Focus is placed on illustrating the broad imaging utility of Ir(III) complexes. Phosphorescent labels illuminating intracellular organelles, including mitochondria, lysosomes, and cell membranes, are summarized. Ir(III) complexes capable of visualization of tumor spheroids and parasites are also introduced. Facile chemical modification of the cyclometalating ligands endows the Ir(III) complexes with strong sensing ability. Sensors of temperature, pH, CO2, metal ions, anions, biosulfur species, reactive oxygen species, peptides, and viscosity have recently been added to the molecular imaging tools. This diverse utility demonstrates the potential of phosphorescent Ir(III) complexes toward bioimaging applications.
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Remarkably flexible 2,2′:6′,2″-terpyridines and their group 8–10 transition metal complexes – Chemistry and applications. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214426] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Maekawa M, Terada K, Oda S, Sugimoto K, Okubo T, Kuroda-Sowa T. Syntheses and structural characterizations of mononuclear Ir(III) hydride complexes with 2,2′:6′,2″-terpyridine in the κ2N,N' and κ3N,N',N″ coordination modes. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.119962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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9
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New yellow-emitting iridium(III) complexes containing 2-phenyl-2H-indazole-based ligands for high efficient OLEDs with EQE over 25%. Inorganica Chim Acta 2020. [DOI: 10.1016/j.ica.2020.119704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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10
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Liu X, Hao H, Ge X, He X, Liu Y, Wang Y, Wang H, Shao M, Jing Z, Tian L, Liu Z. Triphenylamine-appended cyclometallated iridium(III) complexes: Preparation, photophysical properties and application in biology/luminescence imaging. J Inorg Biochem 2019; 199:110757. [DOI: 10.1016/j.jinorgbio.2019.110757] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 06/18/2019] [Accepted: 06/25/2019] [Indexed: 01/07/2023]
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Laha P, De U, Chandra F, Dehury N, Khullar S, Kim HS, Patra S. Alkyl chain-modified cyclometalated iridium complexes as tunable anticancer and imaging agents. Dalton Trans 2018; 47:15873-15881. [PMID: 30358775 DOI: 10.1039/c8dt02461h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2024]
Abstract
Five mononuclear cyclometalated iridium complexes [1](PF6)-[5](PF6) were prepared using imidazole-based ligands of varying alkyl chain length. The complexes were characterised by various analytical techniques. The single crystal X-ray structures of [2](PF6), [3](PF6) and [4](PF6) revealed the expected distorted Oh structures around the metal centre; however, the chain length was found to play a crucial role in deciding the overall geometry. Theoretical investigations demonstrated that the HOMOs were mainly contributed by iridium and cyclometalated ligands, whereas the LUMOs were constituted from bpy/phen units. The complexes were found to be luminescent with a moderate emission quantum yield and lifetime in CH3CN. The in vitro growth inhibition assay of the complexes with a shorter alkyl chain ([4]+ and [5]+) displayed higher anticancer activity (IC50 < 0.5 μM) compared to the complexes with a longer alkyl chain ([1]+-[3]+) (IC50 < 30 μM) against human breast cancer (MCF-7) cells. The complexes [4]+ and [5]+ also displayed moderate cancer cell selectivity (∼3 times) over normal breast (MCF-10) cells. The flow cytometry assay and fluorescence microscopy analysis suggested that cellular accumulation was primarily responsible for the variation in anticancer activity. Interestingly, without possessing any anticancer activity or toxicity ((IC50 > 50 μM), the complex [1]+ mainly accumulated near the cell membrane outside the cell and displayed a clear image of the cell membrane. The light microscopy images and western blot analysis reveal that complex [4]+ induced combined apoptosis and paraptosis. Thus, tuning the anticancer activity and cellular imaging property mediated by the alkyl chain would be of great importance and would be useful in anticancer research.
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Affiliation(s)
- Paltan Laha
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Argul, Jatni-752050, Odisha, India.
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Qu ZZ, Gao TB, Wen J, Rui K, Ma H, Cao DK. Cyclometalated Ir(iii) complexes [Ir(tpy)(bbibH2)Cl][PF6] and [Ir(tpy)(bmbib)Cl][PF6]: intramolecular π⋯π interactions leading to facile synthesis and enhanced luminescence. Dalton Trans 2018; 47:9779-9786. [DOI: 10.1039/c8dt01922c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Complexes [Ir(tpy)(bbibH2)Cl][PF6] (1·PF6) and [Ir(tpy)(bmbib)Cl][PF6] (2·PF6) show facile synthesis and enhanced luminescence due to intramolecular π⋯π interactions.
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Affiliation(s)
- Zhong-Ze Qu
- State Key Laboratory of Coordination Chemistry
- Coordination Chemistry Institute
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
| | - Tai-Bao Gao
- State Key Laboratory of Coordination Chemistry
- Coordination Chemistry Institute
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
| | - Jing Wen
- Key Laboratory of Mesoscopic Chemistry of MOE
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Kai Rui
- State Key Laboratory of Coordination Chemistry
- Coordination Chemistry Institute
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
| | - Haibo Ma
- Key Laboratory of Mesoscopic Chemistry of MOE
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Deng-Ke Cao
- State Key Laboratory of Coordination Chemistry
- Coordination Chemistry Institute
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
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