Linear and circular helicates: A brief review

Paneerselvam, Aruna Priyadarsini; Mishra, Srabani Srotoswini; Chand, Dillip Kumar

doi:10.1007/s12039-018-1497-1

Cited by 31 publications

(12 citation statements)

References 75 publications

(28 reference statements)

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“…Systems have been studied for their anti-cancer and anti-microbial activity and their potential as drug delivery agents. Helicates ( Piguet et al, 1997 ; Albrecht, 2001 ; Hannon and Childs, 2004 ; Howson and Scott, 2011 ; Boiocchi and Fabbrizzi, 2014 ; Paneerselvam et al, 2018 ; Albrecht et al, 2019 ; Albrecht, 2020 ; Tran and Yoo, 2020 ) are one of the earlier known and well-studied sub-classes of MSAs. Lehn and co-workers reported the first helicates; a double-stranded dinuclear and larger trinuclear system were generated from poly(2,2′-bipyridine) ligands and Cu(I) ions ( Lehn et al, 1987 ) Subsequently, single, triple, and quadruple stranded helicates have all been synthesized and these systems are chiral featuring P (plus, right-handed) and M (minus, left-handed) helices ( Figure 1 ).…”

Section: Introductionmentioning

confidence: 99%

Cavity-Containing [Fe2L3]4+ Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity

et al. 2021

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Two new di(2,2′-bipyridine) ligands, 2,6-bis([2,2′-bipyridin]-5-ylethynyl)pyridine (L1) and bis(4-([2,2′-bipyridin]-5-ylethynyl)phenyl)methane (L2) were synthesized and used to generate two metallosupramolecular [Fe2(L)3](BF4)4 cylinders. The ligands and cylinders were characterized using elemental analysis, electrospray ionization mass spectrometry, UV-vis, 1H-, 13C and DOSY nuclear magnetic resonance (NMR) spectroscopies. The molecular structures of the [Fe2(L)3](BF4)4 cylinders were confirmed using X-ray crystallography. Both the [Fe2(L1)3](BF4)4 and [Fe2(L2)3](BF4)4 complexes crystallized as racemic (rac) mixtures of the ΔΔ (P) and ΛΛ (M) helicates. However, 1H NMR spectra showed that in solution the larger [Fe2(L2)3](BF4)4 was a mixture of the rac-ΔΔ/ΛΛ and meso-ΔΛ isomers. The host-guest chemistry of the helicates, which both feature a central cavity, was examined with several small drug molecules. However, none of the potential guests were found to bind within the helicates. In vitro cytotoxicity assays demonstrated that both helicates were active against four cancer cell lines. The smaller [Fe2(L1)3](BF4)4 system displayed low μM activity against the HCT116 (IC50 = 7.1 ± 0.5 μM) and NCI-H460 (IC50 = 4.9 ± 0.4 μM) cancer cells. While the antiproliferative effects against all the cell lines examined were less than the well-known anticancer drug cisplatin, their modes of action would be expected to be very different.

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Section: Introductionmentioning

confidence: 99%

Cavity-Containing [Fe2L3]4+ Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity

et al. 2021

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“…The thermodynamics of multivalent supramolecular assembly can be summarized in terms of two main trends: the “principle of maximum occupancy,” which refers to the tendency of systems to evolve toward the most stable state with full occupancy of binding sites, and the “entropy factor,” which favors the state of the system with the largest number of product species ( 41 ). For most of the supramolecular systems studied to date, the valency (number of binding sites per monomer) is relatively small (<6), the principle of maximum occupancy dominates, and all sites are generally filled in the assembled materials ( 42 , 43 ). However, for high-valence monomers, such as the polyA chains studied here, the entropy factor strongly opposes the principle of maximum occupancy and more complex behavior emerges.…”

Section: Resultsmentioning

confidence: 99%

Using transient equilibria (TREQ) to measure the thermodynamics of slowly assembling supramolecular systems

et al. 2022

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Supramolecular chemistry involves the noncovalent assembly of monomers into materials with unique properties and wide-ranging applications. Thermal analysis is a key analytical tool in this field, as it provides quantitative thermodynamic information on both the structural stability and nature of the underlying molecular interactions. However, there exist many supramolecular systems whose kinetics are so slow that the thermodynamic methods currently applied are unreliable or fail completely. We have developed a simple and rapid spectroscopic method for extracting accurate thermodynamic parameters from these systems. It is based on repeatedly raising and lowering the temperature during assembly and identifying the points of transient equilibrium as they are passed on the up- and down-scans. In a proof-of-principle application to the coassembly of polydeoxyadenosine (polyA) containing 15 adenosines and cyanuric acid (CA), we found that roughly 30% of the CA binding sites on the polyA chains were unoccupied, with implications for high-valence systems.

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“…Thus, cyclic helicates caught our attention because they can be composed of much more components, and therefore, can give rise to much more complex mixtures of diastereomers. Despite the fact that the first example was already reported in 1996 by J.‐M.…”

Section: Methodsmentioning

confidence: 99%

Subcomponent Self‐Assembly of a Cyclic Tetranuclear Fe^II Helicate in a Highly Diastereoselective Self‐Sorting Manner

Anhäuser

Puttreddy

Glanz

et al. 2019

Chemistry A European J

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An enantiomerically pure diamine based on the 4,15‐difunctionalized [2.2]paracyclophane scaffold and 2‐formylpyridine self‐assemble into an optically pure cyclic metallosupramolecular Fe4L6 helicate upon mixing with iron(II) ions in a diastereoselective subcomponent self‐assembly process. The cyclic assembly results from steric strain that prevents the formation of a smaller linear dinuclear triple‐stranded helicate, and hence, leads to the larger strain‐free assembly that fulfils the maximum occupancy rule. Interestingly, use of the racemic diamine also leads to a racemic mixture of the homochiral cyclic helicates as the major product in a highly diastereoselective narcissistic chiral self‐sorting manner given the fact that the assembly contains ten stereogenic elements, which can in principle give rise to 149 different diastereomers. The metallosupramolecular aggregates could be characterized by NMR, UV/Vis and CD spectroscopy, mass spectrometry, and X‐ray crystallography.

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Linear and circular helicates: A brief review

Cited by 31 publications

References 75 publications

Cavity-Containing [Fe2L3]4+ Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity

Cavity-Containing [Fe2L3]4+ Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity

Using transient equilibria (TREQ) to measure the thermodynamics of slowly assembling supramolecular systems

Subcomponent Self‐Assembly of a Cyclic Tetranuclear Fe^II Helicate in a Highly Diastereoselective Self‐Sorting Manner

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Linear and circular helicates: A brief review

Cited by 31 publications

References 75 publications

Cavity-Containing [Fe2L3]4+ Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity

Cavity-Containing [Fe2L3]4+ Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity

Using transient equilibria (TREQ) to measure the thermodynamics of slowly assembling supramolecular systems

Subcomponent Self‐Assembly of a Cyclic Tetranuclear FeII Helicate in a Highly Diastereoselective Self‐Sorting Manner

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Subcomponent Self‐Assembly of a Cyclic Tetranuclear Fe^II Helicate in a Highly Diastereoselective Self‐Sorting Manner