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Okoročenkova J, Filgas J, Khan NM, Slavíček P, Klán P. Thermal Truncation of Heptamethine Cyanine Dyes. J Am Chem Soc 2024; 146:19768-19781. [PMID: 38995720 PMCID: PMC11273355 DOI: 10.1021/jacs.4c02116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024]
Abstract
Cyanine dyes are a class of organic, usually cationic molecules containing two nitrogen centers linked through conjugated polymethine chains. The synthesis and reactivity of cyanine derivatives have been extensively investigated for decades. Unlike the recently described phototruncation process, the thermal truncation (chain shortening) reaction is a phenomenon that has rarely been reported for these important fluorophores. Here, we present a systematic investigation of the truncation of heptamethine cyanines (Cy7) to pentamethine (Cy5) and trimethine (Cy3) cyanines via homogeneous, acid-base-catalyzed nucleophilic exchange reactions. We demonstrate how different substituents at the C3' and C4' positions of the chain and different heterocyclic end groups, the presence of bases, nucleophiles, and oxygen, solvent properties, and temperature affect the truncation process. The mechanism of chain shortening, studied by various analytical and spectroscopic techniques, was verified by extensive ab initio calculation, implying the necessity to model catalytic reactions by highly correlated wave function-based methods. In this study, we provide critical insight into the reactivity of cyanine polyene chains and elucidate the truncation mechanism and methods to mitigate side processes that can occur during the synthesis of cyanine derivatives. In addition, we offer alternative routes to the preparation of symmetrical and unsymmetrical meso-substituted Cy5 derivatives.
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Affiliation(s)
- Jana Okoročenkova
- Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice 5, 625 00 Brno, Czech Republic
- RECETOX,
Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech
Republic
| | - Josef Filgas
- Department
of Physical Chemistry, University of Chemistry
and Technology, Technická 5, 16628 Prague 6, Czech Republic
| | - Nasrulla Majid Khan
- Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice 5, 625 00 Brno, Czech Republic
- RECETOX,
Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech
Republic
| | - Petr Slavíček
- Department
of Physical Chemistry, University of Chemistry
and Technology, Technická 5, 16628 Prague 6, Czech Republic
| | - Petr Klán
- Department
of Chemistry, Faculty of Science, Masaryk
University, Kamenice 5, 625 00 Brno, Czech Republic
- RECETOX,
Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech
Republic
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Li Y, Zhu L, Wu X, Zhang Z, Pu R, Zheng Y, Zhang Z. Paper-in-Tip Bipolar Electrospray Mass Spectrometry for Real-Time Chemical Reaction Monitoring. Angew Chem Int Ed Engl 2024; 63:e202318169. [PMID: 38717236 DOI: 10.1002/anie.202318169] [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: 11/27/2023] [Indexed: 06/19/2024]
Abstract
Capturing short-lived intermediates at the molecular level is key to understanding the mechanism and dynamics of chemical reactions. Here, we have developed a paper-in-tip bipolar electrolytic electrospray mass spectrometry platform, in which a piece of triangular conductive paper incorporated into a plastic pipette tip serves not only as an electrospray emitter but also as a bipolar electrode (BPE), thus triggering both electrospray and electrolysis simultaneously upon application of a high voltage. The bipolar electrolysis induces a pair of redox reactions on both sides of BPE, enabling both electro-oxidation and electro-reduction processes regardless of the positive or negative ion mode, thus facilitating access to complementary structural information for mechanism elucidation. Our method enables real-time monitoring of transient intermediates (such as N,N-dimethylaniline radical cation, dopamine o-quinone (DAQ) and sulfenic acid with half-lives ranging from microseconds to minutes) and transient processes (such as DAQ cyclization with a rate constant of 0.15 s-1). This platform also provides key insights into electrocatalytic reactions such as Fe (III)-catalyzed dopamine oxidation to quinone species at physiological pH for neuromelanin formation.
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Affiliation(s)
- Yun Li
- School of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an, 710065, China
| | - Lixuan Zhu
- School of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an, 710065, China
| | - Xiaomeng Wu
- School of Electronic Engineering, Xi'an Shiyou University, Xi'an, 710065, China
| | - Zhiming Zhang
- School of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an, 710065, China
| | - Ruijin Pu
- School of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an, 710065, China
| | - Yajun Zheng
- School of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an, 710065, China
| | - Zhiping Zhang
- School of Chemistry and Chemical Engineering, Xi'an Shiyou University, Xi'an, 710065, China
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Freitas D, Chen X, Cheng H, Davis A, Fallon B, Yan X. Recent Advances of In-Source Electrochemical Mass Spectrometry. Chempluschem 2021; 86:434-445. [PMID: 33689239 DOI: 10.1002/cplu.202100030] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/03/2021] [Indexed: 12/16/2022]
Abstract
Hyphenation of electrochemistry (EC) and mass spectrometry has become a powerful tool to study redox processes. Approaches that can achieve this hyphenation include integrating chromatography/electrophoresis between electroinduced redox reactions and detection of products, coupling an EC flow cell to a mass spectrometer, and performing electrochemical reactions inside the ion source of a mass spectrometer. The first two approaches have been well reviewed elsewhere. This Minireview highlights the inherent electrochemical properties of many mass spectrometry ion sources and their roles in the coupling of electrochemistry and mass spectrometric analysis. Development of modified ion sources that allow the compatibility of electrochemistry with ionization processes is also surveyed. Applications of different in-source electrochemical devices are provided including intermediate capturing, bioanalytical studies, nanoparticle formation, electrosynthesis, and electrode imaging.
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Affiliation(s)
- Dallas Freitas
- Department of Chemistry, Texas A&M University, 580 Ross St., College Station, TX 77843, USA
| | - Xi Chen
- Department of Chemistry, Texas A&M University, 580 Ross St., College Station, TX 77843, USA
| | - Heyong Cheng
- Department of Chemistry, Texas A&M University, 580 Ross St., College Station, TX 77843, USA
| | - Austin Davis
- Department of Chemistry, Texas A&M University, 580 Ross St., College Station, TX 77843, USA
| | - Blake Fallon
- Department of Chemistry, Texas A&M University, 580 Ross St., College Station, TX 77843, USA
| | - Xin Yan
- Department of Chemistry, Texas A&M University, 580 Ross St., College Station, TX 77843, USA
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Ory L, Gentil E, Kumla D, Kijjoa A, Nazih EH, Roullier C. Detection of ergosterol using liquid chromatography/electrospray ionization mass spectrometry: Investigation of unusual in-source reactions. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8780. [PMID: 32154942 DOI: 10.1002/rcm.8780] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 02/18/2020] [Accepted: 03/08/2020] [Indexed: 06/10/2023]
Abstract
RATIONALE In the field of natural products, de-replication of complex mixtures has become a usual practice to annotate known compounds and avoid their re-isolation. For this purpose, many groups rely on liquid chromatography coupled to high-resolution mass spectrometry (HPLC/MS) to deduce molecular formulae of compounds allowing comparison with public or in-house databases. Electrospray ionization (ESI) is usually considered as the method of choice for investigating a large panel of compounds but, in some cases, it may lead to unusual results as described in this article for ergosterol. METHODS Ergosterol and other fungal sterols in methanolic solution were analysed using various chromatographic gradients with HPLC/MS using both ion trap time-of-flight MS and Orbitrap MS instruments fitted with an ESI source. Further flow injection analyses were performed to investigate the influence of the solvent composition. MS/MS fragmentation data were acquired to annotate the various ions observed. RESULTS Contrary to other fungal sterols, ergosterol was found to be highly sensitive to oxidation during ESI. Putative structures were proposed based on MS/MS studies and known oxidation mechanisms of ergosterol by reactive oxygen species that could be formed in the ESI process. The proportion of acetonitrile in the eluent was found to influence this in-source oxidation, with an increased proportion of oxidized sodium adducts with higher proportions of acetonitrile. CONCLUSIONS While ergosterol is a major sterol found in fungi, this study investigates its ionization by electrospray for the first time. The results reported here will help further detection and annotation of this compound in fungal extracts after HPLC/ESI-MS analyses.
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Affiliation(s)
- Lucie Ory
- EA2160 - MMS, Nantes University, 9 rue Bias, Nantes, 44035, France
| | - Emmanuel Gentil
- EA2160 - MMS, Nantes University, 9 rue Bias, Nantes, 44035, France
- Corsaire - ThalassOMICS, Biogenouest, Université de Nantes, Nantes, 44000, France
| | - Decha Kumla
- ICBAS - Instituto de Ciências Biomédicas Abel Salazar and CIIMAR, Universidade do Porto, Porto, 4050-313, Portugal
| | - Anake Kijjoa
- ICBAS - Instituto de Ciências Biomédicas Abel Salazar and CIIMAR, Universidade do Porto, Porto, 4050-313, Portugal
| | - El-Hassane Nazih
- EA2160 - MMS, Nantes University, 9 rue Bias, Nantes, 44035, France
| | - Catherine Roullier
- EA2160 - MMS, Nantes University, 9 rue Bias, Nantes, 44035, France
- Corsaire - ThalassOMICS, Biogenouest, Université de Nantes, Nantes, 44000, France
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