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Usanovich and Nernst colliding: inconsistencies in the all-in-one acid–base concept?

Flechsig, Gerd-Uwe (2023)

Foundations of Chemistry 2023.
DOI: 10.1007/s10698-023-09482-x


Open Access Peer Reviewed
 

Among the many acid-base concepts, the theory of Usanovich is one of the least known despite the most general scope including almost all chemical reaction types and even redox chemistry. Published 1939 in a Soviet journal in Russian language, it gained little immediate attention, and was later criticized mainly as being too broad in scope. Although several articles recently remembered Usanovich and his acid–base theory, one major inconsistency again was overseen: the electron is put in a row along with anions. Chemical history probably correctly puts this concept aside, also because it added little explanation capabilities beyond the elaborated considerations of the simultaneously published acid–base theory of Gilbert N. Lewis which was later refined by Pearson (hard and soft acids and bases, “HSAB”). A modified version of the core of Usanovich' concept is finally discussed. It combines the classic protic and aprotic acid–base concepts on the foundations of Lewis’ and Pearsons ideas.

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An Amplified Voltammetric H/D Isotope Effect Observed with DNA Self-Assembled Monolayers on Gold Electrodes

Flechsig, Gerd-Uwe; Galagedera, S. K. K. (2023)

Vortrag auf der Konferenz: 74th Annual Meeting of the International Society of Electrochemistry 2023.


Peer Reviewed

Trace Analysis of Metal(II) Pyrithiones in Building Materials by means of Adsorptive Stripping Voltammetry

Befolo, Olivier; Flechsig, Gerd-Uwe (2023)

Wissenschaftliches Poster: 74th Annual Meeting of the International Society of Electrochemistry in Lyon, France 2023.



Usanovich and his all-In-one acid-base concept

Flechsig, Gerd-Uwe (2023)

Centenary Workshop on the Bifurcation of Acidity – Protonism vs. Electronism.


 

This contribution considers the little-known universal acid-base concept of Usanovich. It is quite interesting and useful to see how one can get from the proton-based and quantitative Brönsted-Lowry theory and the electron-based Lewis approach to a comprehensive and unified acid-base concept that includes exchange of all kinds of ions and even electrons. When the consideration of electron exchange touches even redox reactions, however, the Usanovich concept appears to most chemists as too far of a stretch. Publishing the original idea in a Soviet journal in Russian language did not help either in promoting it. Later articles were published in German, and even some English chemistry text books considered the contribution of Usanovich. These chapters, however, would disappear in later editions, and so, what remains today is the fascinating history of acid base concepts that can teach us on how competing ideas contribute to the progress of science in chemistry.


Obituary: Professor Peter Gründler (1940–2019)

Flechsig, Gerd-Uwe (2020)

Journal of Solid State Electrochemistry 24, S. 795–796.
DOI: 10.1007/s10008-020-04518-0


Open Access Peer Reviewed
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Detection of the level of DNA cross-linking with cisplatin by electrochemical quartz crystal microbalance

Galagedera, S. K. K.; Flechsig, Gerd-Uwe (2020)

Journal of Electroanalytical Chemistry 862, 113992.
DOI: 10.1016/j.jelechem.2020.113992


Peer Reviewed
 

Biosensors based on DNA self-assembled monolayers (DNA-SAMs) combined with electrochemical transducers have shown great potential to serve an important role in simple, accurate and inexpensive genetic analysis relevant to many fields. Recently we have reported on observing a significant change in the viscoelasticity of such DNA layers immobilized on gold electrodes, upon redox switching of certain metal complexes at a millisecond time scale using an electrochemical quartz crystal microbalance (EQCM). In this study we have performed chronoamperometry on single stranded and double stranded DNA/6-mercapto-1-hexanol (MCH) mixed SAMs on gold electrodes in the presence of hexaammine ruthenium(III) (RuHex) to monitor the DNA modification with cis-diammine dichloroplatinum(II) (cisplatin). Our EQCM studies confirmed that the redox response of electrostatically bound RuHex is capable of providing quantitative information regarding the extent of DNA cross-linking with cisplatin. We believe that this method can be used in studies to test the interactions of cancer chemotherapeutic medications like cisplatin with ss & dsDNA and ultimately be a new technology for rapid screening of such potential drug candidates that are able to penetrate the blood-brain barrier and interact with DNA in order to inhibit cancer cell growth of brain tumor tissue by forming DNA adducts.

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Amidyl Radical Directed Remote Allylation of Unactivated sp3 C-H Bonds by Organic Photoredox Catalysis

Wu, K.; Wang, L.; Colón-Rodríguez, S.; Flechsig, Gerd-Uwe; Wang, T. (2019)

Angewandte Chemie (International ed. in English) 2019 58 (6), S. 1774–1778.
DOI: 10.1002/anie.201811004


Peer Reviewed
 

The development of visible-light-mediated allylation of unactivated sp3 C-H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre-functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C-H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as d-carbon radical acceptor.

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Prof. Dr. Gerd-Uwe Flechsig


Hochschule Coburg

Fakultät Angewandte Naturwissenschaften und Gesundheit (FNG)
Friedrich-Streib-Str. 2
96450 Coburg

T +49 9561 317 681
Gerd-Uwe.Flechsig[at]hs-coburg.de