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Near-infrared metal agents assisting precision medicine: from strategic design to bioimaging and therapeutic applications. Chem Soc Rev 2023. [PMID: 37334831 DOI: 10.1039/d3cs00227f] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
Metal agents have made incredible strides in preclinical research and clinical applications in recent years, but their short emission/absorption wavelengths continue to be a barrier to their distribution, therapeutic action, visual tracking, and efficacy evaluation. Nowadays, the near-infrared window (NIR, 650-1700 nm) provides a more accurate imaging and treatment option. Thus, there has been ongoing research focusing on developing multifunctional NIR metal agents for imaging and therapy that have deeper tissue penetration. The design, characteristics, bioimaging, and therapy of NIR metal agents are covered in this overview of papers and reports published to date. To start with, we focus on describing the structure, design strategies, and photophysical properties of metal agents from the NIR-I (650-1000 nm) to NIR-II (1000-1700 nm) region, in order of molecular metal complexes (MMCs), metal-organic complexes (MOCs), and metal-organic frameworks (MOFs). Next, the biomedical applications brought by these superior photophysical and chemical properties for more accurate imaging and therapy are discussed. Finally, we explore the challenges and prospects of each type of NIR metal agent for future biomedical research and clinical translation.
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Recent advances of cyclometalated Ir(III) complexes for optical oxygen sensing. Inorganica Chim Acta 2023. [DOI: 10.1016/j.ica.2023.121435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Phosphorescent iridium(III) complexes as lifetime-based biological sensors for photoluminescence lifetime imaging microscopy. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214334] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Heterometal Grafted Metalla-ynes and Poly(metalla-ynes): A Review on Structure-Property Relationships and Applications. Polymers (Basel) 2021; 13:polym13213654. [PMID: 34771211 PMCID: PMC8588132 DOI: 10.3390/polym13213654] [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: 08/30/2021] [Revised: 10/04/2021] [Accepted: 10/20/2021] [Indexed: 11/16/2022] Open
Abstract
Metalla-ynes and poly(metalla-ynes) have emerged as unique molecular scaffolds with fascinating structural features and intriguing photo-luminescence (PL) properties. Their rigid-rod conducting backbone with tunable photo-physical properties has generated immense research interests for the design and development of application-oriented functional materials. Introducing a second d- or f-block metal fragment in the main-chain or side-chain of a metalla-yne and poly(metalla-yne) was found to further modulate the underlying features/properties. This review focuses on the photo-physical properties and opto-electronic (O-E) applications of heterometal grafted metalla-ynes and poly(metalla-ynes).
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Lanthanide clusters of phenanthroline containing a pyridine-pyrazole based ligand: magnetism and cell imaging. Dalton Trans 2021; 50:3593-3609. [PMID: 33624673 DOI: 10.1039/d0dt04122j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this contribution, we report the synthesis, characterization and luminescence-magnetic properties of Ln-clusters (Ln = Gd3+, Eu3+ and Tb3+) using a new pyridine-pyrazole functionalized ligand fitted with a chromophoric phenanthroline backbone. The unorthodox N-rich ligand forms isostructural trinuclear lanthanide complexes with a topology that closely resembles two interdigitating hairpins. The clusters crystallize in chiral space groups and also exhibit chirality for bulk samples, which were further confirmed using solid state CD spectra. Magnetic studies on the complexes reveal their interesting features while the Gd cluster shows a significant cryogenic magnetic cooling behaviour with a moderately high magnetic entropy change of -23.42 J kg-1 K-1 at 7 T and 2 K. On the other hand, Eu and Tb complexes exhibit interesting fluorescence properties. The compounds were subsequently used as fluorescent probes for the imaging of human breast adenocarcinoma (MCF7) cells. Live cell confocal microscopy images show that the complexes penetrate beyond the usual cytoplasm region and can be useful in imaging the nucleus region of MCF7 cells.
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Azido- and amino-substituted dipicolinates for the sensitization of the luminescent lanthanides EuIII and TbIII. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Multiphoton Absorption Iridium(III)–Organotin(IV) Dimetal Complex with AIE Behavior for Both Sensitive Detection of Tyrosine and Antibacterial Activity. ACS APPLIED BIO MATERIALS 2020; 3:8105-8112. [DOI: 10.1021/acsabm.0c01206] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Mitochondriotropic lanthanide nanorods: implications for multimodal imaging. Chem Commun (Camb) 2020; 56:7945-7948. [PMID: 32531009 DOI: 10.1039/d0cc02698k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two-photon active mitochondriotropic lanthanide nanorods for high resolution fluorescence imaging. The presence of Gd in the nanorods also enabled us to utilize this material as a T1-T2 dual-mode contrast reagent for recording magnetic resonance images of the mouse brain.
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Wavelength‐Dependent Singlet Oxygen Generation in Luminescent Lanthanide Complexes with a Pyridine‐Bis(Carboxamide)‐Terthiophene Sensitizer. Chemistry 2020; 26:7274-7280. [DOI: 10.1002/chem.202000587] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/03/2020] [Indexed: 12/11/2022]
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Mitochondrial targeted osmium polypyridyl probe shows concentration dependent uptake, localisation and mechanism of cell death. Dalton Trans 2020; 48:17461-17471. [PMID: 31513202 DOI: 10.1039/c9dt02967b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A symmetric osmium(ii) [bis-(4'-(4-carboxyphenyl)-2,2':6',2''-terpyridine)] was prepared and conjugated to two mitochondrial-targeting peptide sequences; FrFKFrFK (r = d-arginine). The parent and conjugate complexes showed strong near infra-red emission centred at λmax 745 nm that was modestly oxygen dependent in the case of the parent and oxygen independent in the case of the conjugate, attributed in the latter case, surprisingly, to a shorter emission lifetime of the conjugate compared to the parent. Confocal fluorescence imaging of sub-live HeLa and MCF 7 cells showed the parent complex was cell impermeable whereas the conjugate was rapidly internalised into the cell and distributed in a concentration dependent manner. At concentrations below approximately 30 μmol, the conjugate localised to the mitochondria of both cell types where it was observed to trigger apoptosis induced by the collapse of the mitochondrial membrane potential (MPP). At concentrations exceeding 30 μmol the conjugate was similarly internalised rapidly but distributed throughout the cell, including to the nucleus and nucleolus. At these concentrations, it was observed to precipitate a caspase-dependent apoptotic pathway. The combination of concentration dependent organelle targeting, NIR emission coincident with the biological window, and distribution dependent cytotoxicity offers an interesting approach to theranostics with the possibility of eliciting site dependent therapeutic effect whilst monitoring the therapeutic effect with luminescence imaging.
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Non-covalent intramolecular interactions through ligand-design promoting efficient photoluminescence from transition metal complexes. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2019.213094] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Luminescent Ir(iii)–Ln(iii) coordination polymers showing slow magnetization relaxation. Inorg Chem Front 2020. [DOI: 10.1039/c9qi01504c] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two structural types of iridium(iii)–lanthanide(iii) coordination polymers, single-chain Ir2Ln and double-chain Ir4Ln2 (Ln = Gd, Dy, Er, and Yb), have been prepared. SMM behaviour and NIR luminescence were observed for the Ir–Er and Ir–Yb systems.
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Solvatochromic dual luminescence of Eu–Au dyads decorated with chromophore phosphines. Inorg Chem Front 2020. [DOI: 10.1039/c9qi01015g] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chromophore-containing phosphines produce highly solvatochromic gold(i) fluorophores. Their combination with red-emitting Eu centers offers a facile approach to dual emissive complexes with widely tunable luminescence characteristics.
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Luminescent lanthanide complexes with a pyridine-bis(carboxamide)-bithiophene sensitizer showing wavelength-dependent singlet oxygen generation. Dalton Trans 2020; 49:6661-6667. [DOI: 10.1039/d0dt01034k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A new pyridine-bis(carboxamide)-based ligand with a bithiophene pendant, 2Tcbx, was synthesized.
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Mitochondria-localizing dicarbohydrazide Ln complexes and their mechanism of in vitro anticancer activity. Dalton Trans 2020; 49:4404-4415. [DOI: 10.1039/d0dt00210k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dicarbohydrazide Ln complexes trigger SK-OV-3/DDP cell apoptosis via a mitochondrial dysfunction pathway.
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Heteronuclear d-d and d-f Ru(ii)/M complexes [M = Gd(iii), Yb(iii), Nd(iii), Zn(ii) or Mn(ii)] of ligands combining phenanthroline and aminocarboxylate binding sites: combined relaxivity, cell imaging and photophysical studies. Dalton Trans 2019; 48:6132-6152. [PMID: 30990506 DOI: 10.1039/c9dt00954j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A ligand skeleton combining a 1,10-phenanthroline (phen) binding site and one or two heptadentate N3O4 aminocarboxylate binding sites, connected via alkyne spacers to the phen C3 or C3/C8 positions, has been used to prepare a range of heteronuclear Ru·M and Ru·M2 complexes which have been evaluated for their cell imaging, relaxivity, and photophysical properties. In all cases the phen unit is bound to a {Ru(bipy)2}2+ unit to give a phosphorescent {Ru(bipy)2(phen)}2+ luminophore, and the pendant aminocarboxylate sites are occupied by a secondary metal ion M which is either a lanthanide [Gd(iii), Nd(iii), Yb(iii)] or another d-block ion [Zn(ii), Mn(ii)]. When M = Gd(iii) or Mn(ii) these ions provide the complexes with a high relaxivity for water; in the case of Ru·Gd and Ru·Gd2 the combination of high water relaxivity and 3MLCT phosphorescence from the Ru(ii) unit provides the possibility of two different types of imaging modality in a single molecular probe. In the case of Ru·Mn and Ru·Mn2 the Ru(ii)-based phosphorescence is substantially reduced compared to the control complexes Ru·Zn and Ru·Zn2 due to the quenching effect of the Mn(ii) centres. Ultrafast transient absorption spectroscopy studies on Ru·Mn (and Ru·Zn as a non-quenched control) reveal the occurrence of fast (<1 ns) PET in Ru·Mn, from the Mn(ii) ion to the Ru(ii)-based 3MLCT state, i.e. MnII-(phen˙-)-RuIII → MnIII-(phen˙-)-RuII; the resulting MnIII-(phen˙-) state decays with τ ≈ 5 ns and is non-luminescent. This occurs in conformers when an ET pathway is facilitated by a planar, conjugated bridging ligand conformation connecting the two units across the alkyne bridge but does not occur in conformers where the two units are electronically decoupled by a twisted conformation of the bridging ligand. Computational studies (DFT) on Ru·Mn confirmed both the occurrence of the PET quenching pathway and its dependence on molecular conformation. In the complexes Ru·Ln and Ru·Ln2 (Ln = Nd, Yb), sensitised near-infrared luminescence from Nd(iii) or Yb(iii) is observed following photoinduced energy-transfer from the Ru(ii) core, with Ru → Nd energy-transfer being faster than Ru → Yb energy-transfer due to the higher density of energy-accepting states on Nd(iii).
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Multifunctional hypoxia imaging nanoparticles: multifunctional tumor imaging and related guided tumor therapy. Int J Nanomedicine 2019; 14:707-719. [PMID: 30705587 PMCID: PMC6342223 DOI: 10.2147/ijn.s192048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Hypoxia is a common feature of most solid tumors. Having a comprehensive understanding of tumor hypoxia condition is a key to tumor therapy. Many hypoxia imaging nanoparticles have been used for tumor detection. However, simple optical hypoxia imaging is not enough for tumor diagnosis. Also, the tumor therapy process needs the information about the tumor hypoxia condition. Recently, researchers developed multimodal hypoxia tumor imaging nanoparticles and multifunctional hypoxia imaging-guided tumor therapy nanoparticles. The multimodal hypoxia imaging could produce more tumor region information and engage in functional tumor imaging to better understand the tumor condition. The multifunctional hypoxia imaging-guided tumor therapy could monitor the tumor therapy process and evaluate tumor therapeutic effect. Meanwhile, many challenges and limitations are still remaining in the application of multifunctional hypoxia nanoparticles. In this review, we first introduce the types of multifunctional hypoxia imaging nanoparticles. Then we focus on multimodal hypoxia imaging nanoparticles and hypoxia imaging-guided tumor therapy nanoparticles. We also discuss the challenges and future perspectives of this field. There has not been many studies in this field for now. We hope this review would bring more researchers' attention to this field so that it would substantially contribute to tumor precise therapy.
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Phosphorescence Lifetime Imaging (PLIM): State of the Art and Perspectives. SPRINGER SERIES IN CHEMICAL PHYSICS 2019. [DOI: 10.1007/978-3-030-05974-3_6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Emission Tuning of Ir(N∧C)2(pic)-Based Complexes via Torsional Twisting of Picolinate Substituents. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Long-Lived Emissive Probes for Time-Resolved Photoluminescence Bioimaging and Biosensing. Chem Rev 2018; 118:1770-1839. [DOI: 10.1021/acs.chemrev.7b00425] [Citation(s) in RCA: 479] [Impact Index Per Article: 79.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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A multi-responsive luminescent sensor based on a super-stable sandwich-type terbium(iii)-organic framework. Dalton Trans 2018; 45:15492-15499. [PMID: 27711861 DOI: 10.1039/c6dt03057b] [Citation(s) in RCA: 151] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A super-stable multifunctional terbium(iii)-organic framework, namely {[Tb(TATAB) (H2O)2]·NMP·H2O}n (Tb-MOF, H3TATAB = 4,4',4''-s-triazine-1,3,5-triyltri-m-aminobenzoic acid, NMP = N-methyl-2-pyrrolidone) was synthesized. Tb-MOF exhibits a 2D sql structure with binuclear [Tb2(COO)4(H2O)4]2+ units as 4-connected nodes, and free water and NMP molecules are inserted between 2D layers through hydrogen-bonding interactions, forming a sandwich-type architecture. Observably, such a framework remains intact in a remarkable variety of environments such as common solvents and aqueous solutions with metal cations and inorganic anions, as well as with a pH ranging from 1 to 13. In particular, Tb-MOF can not only detect small organic molecules, metal cations and inorganic anions with high sensitivity and high selectivity, but also can accurately detect explosive 2-nitrophenol, 3-nitrophenol, 4-nitrophenol and 2,4,6-trinitrophenol in water. Its luminescence quenching response to Fe3+ and Cr2O72- ions can be explained in terms of the competitive absorption mechanism. In addition, the luminescence intensity of Tb-MOF is strongly correlated with the pH value in a pH range from 1 to 13. Thus, this material can be potentially used as a multi-responsive luminescent sensor.
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Recent Progress on the Exploration of the Biological Utility of Cyclometalated Iridium(III) Complexes. J CHIN CHEM SOC-TAIP 2018. [DOI: 10.1002/jccs.201700379] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Non-covalent tetrel bonding interactions in hemidirectional lead(ii) complexes with nickel(ii)-salen type metalloligands. NEW J CHEM 2018. [DOI: 10.1039/c7nj05148d] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tetrel bonding interactions have been investigated in hetero-dinuclear nickel(ii)/lead(ii) complexes using MEP and DFT calculations.
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The influence of molecular structure on collision radius for optical sensing of molecular oxygen based on cyclometalated Ir(iii) complexes. RSC Adv 2018; 8:41040-41047. [PMID: 35557895 PMCID: PMC9091647 DOI: 10.1039/c8ra07115b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 12/03/2018] [Indexed: 11/21/2022] Open
Abstract
Three triphenylamine (TPA) substituted cyclometalated Ir(iii) complexes IrA1, IrA2, and IrA3 based on Ir(ppy)3 were synthesized and applied as phosphorescent probes for the monitoring of molecular oxygen. The phosphorescence intensity of all the Ir(iii) complexes in tetrahydrofuran (THF) was gradually quenched with an increase of oxygen concentration. The increase of TPA substituents on the meta-position of 2-phenylpyridine (IrA1-IrA3) gradually improved the oxygen sensitivity of cyclometalated Ir(iii) complexes. IrA3 showed the highest oxygen sensitivity in THF with a KappSV of 204.8 bar−1 and a limit of detection (LOD) of 0.27 mbar. The relationship between molecular structure and the collision radiuses (σ) of all the Ir(iii) complexes has been investigated on the basis of the Demas model and the fundamental expression of luminescence quenching systems by oxygen. The ratio of collision radiuses are σIrA1/σIr(ppy)3 = 1.27 ± 0.05, σIrA2/σIr(ppy)3 = 1.72 ± 0.10, and σIrA3/σIr(ppy)3 = 2.13 ± 0.07, respectively. The introduction and increase of TPA substituents can obviously increase the collision radiuses of cyclometalated Ir(iii) complexes which leading to potential oxygen sensitivity. And the incremental effect of collision radiuses caused by the introduction of TPA substituents resulted in outstanding oxygen sensitivity of IrA3. The results demonstrate for the first time evidence between molecular structure and oxygen sensitivity of the emitters for optical sensing. The triphenylamine substituents increased the collision radiuses of cyclometalated Ir(iii) complexes which leading to potential oxygen sensitivity.![]()
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On the importance of Pb⋯X (X = O, N, S, Br) tetrel bonding interactions in a series of tetra- and hexa-coordinated Pb(ii) compounds. CrystEngComm 2018. [DOI: 10.1039/c8ce00919h] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We study Pb⋯X (X = N, S, Br) tetrel bonding interactions in a series of tetra- and hexa-coordinated Pb(ii) compounds that exhibit hemidirectional coordination.
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Syntheses, Crystal Structures and Luminescent Properties of a Series of Ag-Ln Coordination Polymers. ChemistrySelect 2017. [DOI: 10.1002/slct.201701456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Linking Re I and Pt II Chromophores with Aminopyridines: A Simple Route to Achieve a Complicated Photophysical Behavior. Chemistry 2017. [PMID: 28636113 DOI: 10.1002/chem.201701539] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The bifunctional aminopyridine ligands H2 N-(CH2 )n -4-C5 H4 N (n=0, L1; 1, L2; 2, L3) have been utilized for the preparation of the rhenium complexes [Re(phen)(CO)3 (L1-L3)]+ (1-3; phen=phenanthroline). Complexes 2 and 3 with NH2 -coordinated L2 and L3, respectively, were coupled with cycloplatinated motifs {Pt(ppy)Cl} and {Pt(dpyb)}+ (ppy=2-phenylpyridine, dpyb=dipyridylbenzene) to give the bimetallic species [Re(phen)(CO)3 (μ-L2/L3)Pt(ppy)Cl]+ (4, 6) and [Re(phen)(CO)3 (μ-L2/L3)Pt(dpyb)]2+ (5, 7). In solution, complexes 4 and 6 show 3 MLCT {Re}-based emission at 298 K, which changes to the 3 IL(ppy) state at 77 K. The photophysical properties of compounds 5 and 7 display a pronounced concentration dependence, presumably due to the formation of bimolecular aggregates. Analysis of the spectroscopic data, combined with TD-DFT simulations, suggest that unconventional heteroleptic {Re(phen)}⋅⋅⋅{Pt(dpyb)} π-π stacking operates as the driving force for ground-state association. The latter, together with intra- and intermolecular energy-transfer processes, determines the appearance of multiple emission bands and results in nonlinear relaxation kinetics of the excited states.
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Exploring the Chemistry and Photophysics of Substituted Picolinates Positional Isomers in Iridium(III) Bisphenylpyridine Complexes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00179] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Two-Photon Absorbing Phosphorescent Metalloporphyrins: Effects of π-Extension and Peripheral Substitution. J Am Chem Soc 2016; 138:15648-15662. [PMID: 27934026 PMCID: PMC8281454 DOI: 10.1021/jacs.6b09157] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ability to form triplet excited states upon two-photon excitation is important for several applications of metalloporphyrins, including two-photon phosphorescence lifetime microscopy (2PLM) and two-photon photodynamic therapy (PDT). Here we analyzed one-photon (1P) and degenerate two-photon (2P) absorption properties of several phosphorescent Pt (II) porphyrins, focusing on the effects of aromatic π-extension and peripheral substitution on triplet emissivity and two-photon absorption (2PA). Our 2PA measurements for the first time made use of direct time-resolved detection of phosphorescence, having the ability to efficiently reject laser background through microsecond time gating. π-Extension of the porphyrin macrocycle by way of syn-fusion with two external aromatic fragments, such as in syn-dibenzo- (DBP) and syn-dinaphthoporphyrins (DNP), lowers the symmetry of the porphyrin skeleton. As a result, DBPs and DNPs exhibit stronger 2PA into the one-photon-allowed B (Soret) and Q states than fully symmetric (D4h) nonextended porphyrins. However, much more 2P-active states lie above the B state and cannot be accessed due to the interfering linear absorption. Alkoxycarbonyl groups (CO2R) in the benzo-rings dramatically enhance 2PA near the B state level. Time-dependent density functional theory (TDDFT) calculations in combinations with the sum-over-states (SOS) formalism revealed that the enhancement is due to the stabilization of higher-lying 2P-active states, which are dominated by the excitations involving orbitals extending onto the carbonyl groups. Furthermore, calculations predicted even stronger stabilization of the 2P-allowed gerade-states in symmetric Pt octaalkoxycarbonyl-tetrabenzoporphyrins. Experiments confirmed that the 2PA cross-section of PtTBP(CO2Bu)8 near 810 nm reaches above 500 GM in spite of its completely centrosymmetric structure. Combined with exceptionally bright phosphorescence (ϕphos = 0.45), strong 2PA makes Pt(II) complexes of π-extended porphyrins a valuable class of chromophores for 2P applications. Another important advantage of these porphyrinoids is their compact size and easily scalable synthesis.
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The effect of imidazole on the enhancement of gadolinium-porphyrin phosphorescence at room temperature. Dalton Trans 2016; 45:16889-16895. [DOI: 10.1039/c6dt03197h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The mechanism for the 40-fold enhancement in Gd-HMME RTP intensity by adding imidazole and Gd3+ is revealed.
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