Interactions of helquats with chiral acidic aromatic analytes investigated by partial-filling affinity capillary electrophoresis

Růžička, Martin; Koval, Dušan; Vávra, Jan; Reyes‐Gutiérrez, Paul E.; Teplý, Filip; Kašička, Václav

doi:10.1016/j.chroma.2016.08.053

Cited by 26 publications

(19 citation statements)

References 52 publications

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“…Hence, ACE possesses a great potential for investigation of the (bio)molecular noncovalent interactions under mild conditions and for estimation of binding (stability, association, formation) or dissociation constants of the formed complexes as demonstrated in several recent reviews and research articles . ACE involves several modes based either on the separation of the interacting species and determination of their equilibrium concentration, such as in the Hummel–Dreyer method , the vacancy peak method , frontal analysis , continuous frontal analysis , and kinetic CE , or on the detection of a specific physicochemical property of the complexed ligand or the binding partner, mostly the changes of effective mobility in the mobility shift assay or changes of migration times in the partial‐filling ACE . All these methods utilize the differences in the migration velocities of the interacting species.…”

Section: Separations By the Particular Ce And Cec Methodsmentioning

confidence: 99%

Recent developments in capillary and microchip electroseparations of peptides (2015–mid 2017)

Kašička

2017

Electrophoresis

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The review brings a comprehensive overview of recent developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) to analysis, microscale isolation, purification, and physicochemical and biochemical characterization of peptides in the years 2015, 2016, and ca. up to the middle of 2017. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis (sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, and detection) are described. New developments in particular CE and CEC methods are presented and several types of their applications to peptide analysis are reported: qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC methods to provide important physicochemical characteristics of peptides are demonstrated.

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Section: Separations By the Particular Ce And Cec Methodsmentioning

confidence: 99%

Recent developments in capillary and microchip electroseparations of peptides (2015–mid 2017)

Kašička

2017

Electrophoresis

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“…However, these two peaks were too close to each other to be able to perform efficient enantiomeric separation. 226…”

Section: Helquats: Synthesis By [2+2+2] Cycloisomerization and Propermentioning

confidence: 99%

“…Kasicka et al 226 investigated the non-covalent molecular interactions between Helquats, and several chiral acidic aromatic drugs (including warfarin, ibuprofen, mandelic acid, etodolac, binaphthylphosphate) by using the partial-filling affinity capillary electrophoresis (PF-ACE) technique. For example, enantioselective interaction was observed for (R) and (S)-enantiomers of 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BNP) X7 with [7]Helquat [(P)-250] 2+ ( Figure 34) in favor of the (S): 394 ± 77 vs. 870 ± 138 L mol -1 .…”

Section: Scheme 57 Synthesis Of Racemic Cationic Azahelicenes [240amentioning

confidence: 99%

Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P)

2019

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In this review, we discuss the rich chemistry of helicenes and helicenoids containing maingroup elements. Enantioenriched helicenic derivatives containing main-group elements B, Si, N and P, either incorporated within the helical backbone or grafted to it, will be thoroughly presented. We will describe their synthesis, resolution, and asymmetric synthesis, their structural features, electronic and chiroptical properties, emission, together with other photochemical properties and applications. OUTLINE 14 The absorption spectrum of 19c recorded in CH 2 Cl 2 solutions exhibited a maximum at 376 nm which is significantly red shifted compared with that of double [5]helicene 19a (310 nm) due to the more extended π-conjugation in 19c. According to TD-DFT calculations, the low-energy absorption band from 400 to 500 nm is assignable to the HOMO→LUMO transition corresponding to a π−π* transition of the fully conjugated bis-helical system. DFT calculations revealed a very high theoretical isomerization barrier of 45.1 kcal/mol for the (P,P)/(M,M)-19c stereoisomer, i.e. 4.4 kcal/mol higher than the (P,M) stereoisomer (not observed experimentally). The high configurational stability of 19c enabled to obtain the pure (P,P)and (M,M)-19c by chiral HPLC (Daicel Chiralcel IE column; EtOAc/MeOH = 9:1 as eluent) and to study their chiroptical properties. The ECD spectrum of (P,P)-19c in CH 2 Cl 2 displayed two strong positive bands at 275 and 320 nm, a strong negative one at 375 nm and a broad and less intense one between 425-475 nm. 52 Note that the isomerization barrier of the OBO-fused double [7]helicene is much higher than for oxabora[6]helicene 9 (vide supra) and higher than carbo[7]helicene (42.0 kcal/ mol), indicating the advantage of double helicenes over monohelicenes in terms of conformational stability. Indeed no racemization was observed upon heating enantiomer (P,P) and (M,M)-19c for 24 h up to 200 °C. 52 Note that in 2017 a longer double OBO-helicene analogue was deposited on a Au(111) under UHV conditions and its surface-assisted cyclodehydrogenation into a planar OBO-perihexacene was observed by STM. 54 Similarly to 6 and 9, the strong bond alternation found in the BOC4 rings of 19a 51 may account for the small NICS value of 1.3 while the surrounding C6 rings, including the distorted central benzene ring, show large negative NICS values (Scheme 3c). For comparison, in the all-carbon analogue tetrabenzo-[a,f,j,o]perylene shown in Scheme 3c, the central C6 ring shows a positive NICS value, indicating substantial antiaromatic character. Notably, molecular orbital calculations of 19a indicate that the HOMO and LUMO are spread over the C6 rings rather than on the boron and oxygen atoms, accounting for the substantial stability of 19a (Scheme 3c). Borahelicenes are efficient blue fluorophores. Indeed, azabora[6]helicene 6 displays blue fluorescence at 447 nm (Table 2), while smaller achiral [4]helicenic systems were successfully used as host materials in phosphorescent OLEDs with efficiencies better than the classical 4,4'...

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“…This can be prerequisite for coupling the separation with a mass spectrometric detection or it significantly contributes to reducing a noise, especially when the ligand is UV‐absorbing [i]. Low consumption of a (possibly expensive, rare) ligand is another big advantage of the pf‐ACE .…”

Section: Introductionmentioning

confidence: 99%

“…Eq. supposes the complexation between the analyte and the ligand in a simple 1:1 stoichiometric ratio and fast enough rate of the complexation equilibrium, and

c_{L}

refers to the total (analytical) concentration of the ligand .…”

Section: Introductionmentioning

confidence: 99%

Into the theory of the partial‐filling affinity capillary electrophoresis and the determination of apparent stability constants of analyte‐ligand complexes

2018

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The partial-filling affinity capillary electrophoresis (pf-ACE) works with a ligand present in a background electrolyte that forms a weak complex with an analyte. In contrast to a more popular mobility-shift affinity capillary electrophoresis, only a short plug of the ligand is introduced into a capillary in the pf-ACE. Both methods can serve for determining apparent stability constants of the formed complexes but this task is hindered in the pf-ACE by the fact that the analyte spends only a part of its migration time in a contact with the ligand. In 1998, Amini and Westerlund published a linearization strategy that allows for extracting an effective mobility of an analyte in the presence of a neutral ligand out of the pf-ACE data. The main purpose of this paper is to show that the original formula is only approximate. We derive a new formula and demonstrate its applicability by means of computer simulations. We further inspect several strategies of data processing in the pf-ACE regarding a risk of an error propagation. This establishes a good practice of determining apparent stability constants of analyte-ligand complexes by means of the pf-ACE.

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Interactions of helquats with chiral acidic aromatic analytes investigated by partial-filling affinity capillary electrophoresis

Cited by 26 publications

References 52 publications

Recent developments in capillary and microchip electroseparations of peptides (2015–mid 2017)

Recent developments in capillary and microchip electroseparations of peptides (2015–mid 2017)

Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P)

Into the theory of the partial‐filling affinity capillary electrophoresis and the determination of apparent stability constants of analyte‐ligand complexes

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