In this review, pseudorotaxanes and rotaxanes structured out of simple crown ethers and linear organic molecules with positively charged nitrogen centres (i.e., quaternary pyridinium groups, viologens like paraquat and also extended viologens, imidazolium groups, benzimidazolium groups, bis-benzimidazolium groups and their derivatives) are described. Some selected examples of such systems are assembled here with respect to their properties and applications. © 2017, Springer Science+Business Media Dordrecht.

CHHANDA MUKHOPADHYAY

Chemistry

S GHOSH

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Inclusion Phenomena and Macrocyclic Chemistry

In this present study we explore the mechanically interlocked molecules (MIMs) resulting from the combination of the BBIM(bis-benzimidazolium)-alkane systems with DB30C10 (Dibenzo-30-crown-10) in solvent acetonitrile. The (BBIM-alkane)DB30C10 systems chosen for the study are (BBIM)DB30C10, (BBIM-methane)DB30C10, (BBIM-ethane)DB30C10, (BBIM-propane)DB30C10 and (BBIM-butane)DB30C10. 1H NMR, 2D-NMR (COSY and NOESY), Monte Carlo calculations and HRMS have been done on the studied assemblies. Even though (BBIM)DB30C10 and (BBIM-methane)DB30C10 form normal threaded structures, in (BBIM-ethane)DB30C10, (BBIM-propane)DB30C10 and (BBIM-butane)DB30C10 systems the respective axles are cradled inside the crown ether. That is, the axles BBIM-ethane, BBIM-propane and BBIM-butane are cradled inside the boat-like cavity of DB30C10. © 2015 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

The idiosyncrasies of (BBIM-alkane)DB30C10 MIMs

Bis(benzimidazolium)butane (BBIM-butane) system acts as a new guest molecule for dibenzo-24-crown-8 (DB24C8). This is the only [BBIM]DB24C8 pseudorotaxanes where two conformers coexist (detected by 1 H NMR and structure established by DFT studies); major conformer and minor conformer. Low temperature 1 H NMR (240, 253 K) was done for a representative [BBIM-butane] DB24C8 pseudorotaxane that could not be detected at room-temperature. DFT calculations for this [BBIM-butane] DB24C8 pseudorotaxane were done both with B3LYP and MPW1PW91 functionals. The MPW1PW91 optimized structures identified possible stable major and minor conformer with the strongest H-bonding. We have compared the characteristics of [BBIM]DB24C8 [2]pseudorotaxanes comprising the [BBIM-methane]DB24C8, [BBIM-ethane] DB24C8, [BBIM-propane]DB24C8 and [BBIM-butane] DB24C8 systems. The feasibility of formation of these pseudorotaxanes decreases considerably from [BBIMmethane] DB24C8 to the [BBIM-butane]DB24C8 system. The presence of these threaded complexes was initially screened based on 1 H NMR and substantiated further by 2D NMR spectroscopy (NOESY and COSY), X-ray crystallography, HR-ESI-MS and DFT calculations. © 2014 Springer Science+Business Media Dordrecht.

Anomalous behaviour of the bis(benzimidazolium)butane [2]pseudorotaxanes of dibenzo-24-crown-8: A comparative study of methane, ethane, propane and butane bis(benzimidazolium)alkane]dibenzo-24-crown-8 systems with variable spacers

Pseudorotaxanes from the self-assembly of simple 2,2′-bis(benzimidazolium) dications and DB24C8 is a first of its kind when a protonated bis(benzimidazole) without a methylene spacer between the two benzimidazolium units (a very rigid axle without flexibility) thread DB24C8 as a result of H-bonding interactions. The formation of these pseudorotaxanes was first ascertained from 1H NMR spectroscopy and later corroborated by HRMS, 2D NMR and finally supported by rigorous DFT calculations. © 2014 Elsevier Ltd. All rights reserved.

Tetrahedron

A 2,2â€²-bis(benzimidazolium)-dibenzo[24]crown[8] rigid pseudorotaxane system

A new [2]pseudorotaxane containing a benzimidazolium hydrogen-bonding station for a dibenzo-24-crown-8 (DB24C8) macrocycle is described. The structure of the [2]pseudorotaxane formed is established by 1H NMR spectroscopy, 2D NOESY and a Monte Carlo protocol (including an anion for the first time). © 2014 the Partner Organisations.

RSC Advances

The new threading system 2-benzyl-5,6-dimethyl-1H-benzo[d]imidazolium- dibenzo-24-crown-8: A model for Monte Carlo calculations incorporating an anion for the first time in threaded structures

We investigated the threading of bis(benzimidazolium) methane moieties with DB24C8 at 35°C (room temperature) and found a high degree of association. The presence of threaded complexes was determined by 1H NMR and also supported by high resolution mass spectrometry and B3LYP/6- 31G**++calculations. A 2D NMR study was done to elucidate the host-guest geometry and the molecular interactions present. The variable temperature NMR experiment was done over a temperature range of 243-323 K. The threading was stable and visible even at 323 K. Acid-base equilibrium established the reversibility of the process. DFT optimized structures establish that two H-bonded links are present between O 1⋯O 4′ and O 3⋯O 2′ across the dibenzo axis of the crown. © 2012 Elsevier Ltd. All rights reserved.

Journal	Data powered by TypesetJournal of Inclusion Phenomena and Macrocyclic Chemistry
Publisher	Data powered by TypesetSpringer Netherlands
ISSN	0923-0750
Open Access	No