Co(II) and Fe(II) triazole-appended 4,10-diaza-15-crown-5-ether Macrocyclic complexes for CEST MRI applications

Snyder, Eric M.; Chowdhury, Saiful I.; Morrow, Janet R.

doi:10.1016/j.ica.2020.119649

Cited by 6 publications

(3 citation statements)

References 34 publications

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“…In the case of the click‐reaction, ascorbic acid was added to the reaction mixture to avoid oxidation of copper(I)‐catalyst. In the applied conditions the reaction is regioselective and results in only the 1,4‐isomer of the triazole [37–40] . Triazole 19 proved to be stable at room temperature for about 1 week, while when it was stored at −30 °C under argon atmosphere, acridone 12 began to form after about a month.…”

Section: Resultsmentioning

confidence: 99%

“…In the applied conditions the reaction is regioselective and results in only the 1,4-isomer of the triazole. [37][38][39][40] Triazole 19 proved to be stable at room temperature for about 1 week, while when it was stored at À 30°C under argon atmosphere, acridone 12 began to form after about a month. Attempts were also made to prepare a derivative containing an ethynyl group at position 9 of the acridine unit.…”

Section: Experiments Nomentioning

confidence: 99%

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Synthesis and Spectrophotometric Studies of 9‐Substituted‐4,5‐dimethoxyacridine Multifunctionalizable Fluorescent Dyes and Their Macrocyclic Derivatives

et al. 2021

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Acridine derivatives are widely used as antiseptics, disinfectants, antibiotics, and fluorescent dyes as well as a subunit of optical sensor molecules of various analytical applications. We reported here the synthesis of several new 9‐substituted‐4,5‐dimethoxyacridine derivatives (9‐bromo‐, 9‐(p‐methylphenyl)‐, 9‐(p‐benzyloxyphenyl)‐, 9‐azido‐, 9‐phenyltriazole‐, 9‐[(trimethylsilyl)ethynyl]‐, 9‐nitrile‐) as potential multifunctionalizable fluorescent precursors of sensor molecules, indicators or dyes including optimized procedures for preparation of 9‐haloacridines and their cross‐coupling reactions. Improved stability of several new compounds could be achieved by the synthetic modification at position 9 of the acridine unit compared to their unsubstituted acridine analogs. The basic spectroscopic characteristics of these useful intermediates were also determined. The new fluorescent compounds showed promising photochemical properties for optochemical‐based applications in the future. The extremely large Stokes‐shifts (above 15500 cm−1) should especially be emphasized. Moreover, the effects of the substituents at position 9 of the acridine unit on fluorescence signaling were studied by the examples of new precursors and their macrocyclic derivatives as known optical sensor molecules. Some interesting relationships between quantum yield and structural features were reported.

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Section: Resultsmentioning

confidence: 99%

Section: Experiments Nomentioning

confidence: 99%

Synthesis and Spectrophotometric Studies of 9‐Substituted‐4,5‐dimethoxyacridine Multifunctionalizable Fluorescent Dyes and Their Macrocyclic Derivatives

et al. 2021

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“…It has been observed that the triazole ring can coordinate with metal ions via the N2 nitrogen atom to form stable complexes when there are neighboring assisting groups. [49][50][51] It was proposed that the interaction between the chemosensor and the metal ion occurs between the coumarin carbonyl and triazole nitrogen via a stable pseudo-six-membered ring as shown in Figure 17. The complexation affinity was attributed to the N-2 nitrogen lone electron pair donation from the triazole ring to the metal ion, assisted by a lone pair of electrons from the coumarin-carbonyl group.…”

Section: Proposed Binding Site Between S1 and Fe 3+mentioning

confidence: 99%

Synthesis and application of a fluorescent “turn-off” triazolyl-coumarin-based fluorescent chemosensor for the sensing of Fe3+ ions in aqueous solutions

Mama¹,

Battison²

2020

Arkivoc

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Two coumarin derivatives containing triazole moieties have been synthesized using "click chemistry" protocol and investigated as chemosensors for the detection of metal ions. These compounds displayed a strong preference for Fe 3+ ions with complexation resulting in fluorescent quenching. The detection limit of the preferred chemosensor was determined to be 1.4 µM. The preferred triazole-coumarin compound showed greater selectivity towards Fe 3+ in the presence of competing metal cations. Binding stoichiometry between this triazole-coumarin and Fe 3+ was shown to occur in a 1:1 ratio between the chemosensor and metal cation. The binding site of Fe 3+ to the triazole-coumarin was determined using 1 H NMR, 13 C NMR and molecular modeling studies.

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Transition Metal ParaCEST, LipoCEST, and CellCEST Agents as MRI Probes

Morrow

Chowdhury

Abozeid

et al. 2020

Encyclopedia of Inorganic and Bioinorganic Chemistry

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First‐row transition metal (TM) complexes are of interest as members of a relatively new class of coordination complexes that produce MRI contrast through CEST (chemical‐exchange saturation transfer). CEST reduces the intensity of the water protons upon exchange of a selectively magnetically saturated proton with the water proton pool. Paramagnetic TM complexes produce large paramagnetically shifted protons, which facilitates CEST signal intensity by avoiding tissue background signal (paraCEST agents) and also allowing for faster proton‐exchange rates. TM paraCEST agents have certain advantages over lanthanide paraCEST agents including the possibility of tuning oxidation and spin states to allow for the development of responsive agents. Moreover, the covalent bonding character of the TM ions bestows large through‐bond contributions to the hyperfine shifts of protons, which is beneficial for paraCEST agents. New applications include the development of TM water proton shift reagents (SRs) for improvement of sensitivity through incorporation into supramolecular assemblies. Liposomes with encapsulated and amphiphilic SRs produce lipoCEST, and cells loaded with SRs produce cellCEST. This article summarizes TM paraCEST agents and SRs and highlights new research directions.

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Co(II) and Fe(II) triazole-appended 4,10-diaza-15-crown-5-ether Macrocyclic complexes for CEST MRI applications

Cited by 6 publications

References 34 publications

Synthesis and Spectrophotometric Studies of 9‐Substituted‐4,5‐dimethoxyacridine Multifunctionalizable Fluorescent Dyes and Their Macrocyclic Derivatives

Synthesis and Spectrophotometric Studies of 9‐Substituted‐4,5‐dimethoxyacridine Multifunctionalizable Fluorescent Dyes and Their Macrocyclic Derivatives

Synthesis and application of a fluorescent “turn-off” triazolyl-coumarin-based fluorescent chemosensor for the sensing of Fe3+ ions in aqueous solutions

Transition Metal ParaCEST, LipoCEST, and CellCEST Agents as MRI Probes

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