<i>Syn/Anti</i> Pair of Triazole‐Bridged Cryptophanes: Synthesis, Characterization with Crystal Structures

Satha, Pardhasaradhi; Illa, Giri Teja; Hazra, Sohan; Purohit, Chandra Shekhar

doi:10.1002/slct.201702086

Cited by 5 publications

(6 citation statements)

References 39 publications

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“…Syn and anti‐isomers of a cryptophane with triazole containing linker is reported earlier by our group [24] . A template approach was followed where vanillyl alcohol groups are appended to CTG derivative utilizing click reaction to form pre‐cryptophane.…”

Section: Methodsmentioning

confidence: 99%

“…Syn and anti-isomers of a cryptophane with triazole containing linker is reported earlier by our group. [24] A template approach was followed where vanillyl alcohol groups are appended to CTG derivative utilizing click reaction to form precryptophane. Finally, it was cyclized intramolecularly using boron trifluoride-diethyl etherate in dry acetonitrile (See supporting information Scheme S1).The linker with a triazole ring has eight atoms in the chain.…”

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confidence: 99%

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Desolvation Induced Conformational Transition in a Cryptophane Host: Crystal To Crystal Transformation

Ghosh,

Hossain,

Saradhi Satha

et al. 2023

Chemistry An Asian Journal

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Cryptophanes show different conformations in solution and solid state depending upon various factors, such as the length of connecting linkers, medium, and nature of the incoming guest molecule(s). A cyclotriguaiacylenes (CTG) based cryptophane molecule was synthesized using click chemistry containing three triazole linkers and studied as well. This molecule shows two conformations, out-out crown-crown (CC), and out-in CC, in the presence or absence of guest molecule(s), as studied both in solution and solid state. The out-in CC, in which both CTG fragments are in crown conformation with one crown sitting above the other, could be obtained by slow escape of the trapped acetone molecules from out-out CC in solid state. This transformation could be obtained through a single-crystal-to-single-crystal (SCSC) transformation from a large volume out-out CC to a smaller volume out-in CC conformation which is also supported by density functional theory calculations.Cavitands are organic molecules with enforced cavity large enough to encapsulate various small molecule(s). [1] The interior cavity of cavitands have been used for stabilization of unstable molecules, [2,3] trapping of reaction intermediate(s), [1e,4] visible light photocatalysis, [5] asymmetric catalysis, [6] enantioselective recognition, [7] for stabilizing reactive intermediates, [7] as microreaction chambers, [8,9] chlorine capture with attomolar affinity, [10] modulate chiroptical properties. [11] Cryptophanes, are one such class of molecules, [12] contain two bowl shaped cyclic molecular systems (cyclotribenzylenes or its derivatives), joined together with three linkers. Changing linker size changes the free space of the cavity considerably. [13,14] Cryptophanes are well studied for entrapment of small neutral guest molecules CHCl 3 , CH 2 Cl 2 , CHFClBr, [13a] cationic organic molecules, [15,16] metal ions, [17] and gases like Xe, CFCs, CH 4 in solution phase. [13,18] These molecules are shown to bind biologically important molecules such as choline and avidin. [16] Typically, cryptophanes remain in an outout CC conformation, in which the connecting methylene groups in the cryptophane unit pointed oppositely outward. However, when flexible enough, i. e., the connecting alkyl chain contains 6 or more carbons, one of the cyclotribenzylenes (CTBs) unit flips to give an out-in CC conformation (Scheme 1).In cryptophanes, one of the factors that governs the feasibility of host-guest complexation is length of the linker. Thus, with an optimise linker length, small molecule can trigger the conversion of out-out CC to out-in CC or vice-versa. Such stimuli-responsive materials have potential applications in sensors, actuators, photoelectronic devices, information storage etc. [19] When changes occur due to escape of the trapped guest molecule(s), compresses the crystals and such systems are proposed to be helpful in designing the high-energy molecular actuators. [20] Out-out CC conformer in cryptophanes is generally found in solid state with small...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Desolvation Induced Conformational Transition in a Cryptophane Host: Crystal To Crystal Transformation

Ghosh,

Hossain,

Saradhi Satha

et al. 2023

Chemistry An Asian Journal

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“…Purohit et al reported the synthesis of triazole-bridged cryptophanes by using the CuI-catalyzed click reaction (Scheme 10). [59] The synthesis was first attempted via the coupling approach, for which two CTB units tripropargyl-CTB 65 and triazide-CTB 67 were prepared from 1. The CTBs 65 and 67 were subjected to click reaction conditions aimed at generating the triazole-bridged cryptophane.…”

Section: Synthesis Of Cryptophanes By the Template Methodsmentioning

confidence: 99%

Synthesis of Cryptophanes: Recent Advances

Kancherla,

Hansen

2024

Eur J Org Chem

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This review covers the latest developments in the synthesis of cryptophane host molecules since the publication of the last extensive review by Brotin and Dutasta in 2009. The literature has been categorized according to the synthetic method for generating the cryptophane core and we also emphasize emerging late‐stage functionalization approaches. The synthetic strategies towards cryptophanes can be broadly categorized into the well‐established direct‐ (two‐step), template‐ and coupling (or capping) methods. The examples covered in this review mainly highlight template‐based synthesis, coupling approaches and late‐stage functionalization.

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“…In the past, these molecules have received a lot of attention because they can accommodate different atoms or molecules within their cavity. For example, it has been shown that neutral (methane, xenon, halogenomethanes) or charged (alkali cations, ammonium, anions) species can easily enter the cavity of these host molecules, depending on the cavity size and the nature of the substituents grafted on to the benzene rings , . Interestingly, the encapsulation process strongly modifies the physical properties of both the guest and host molecules, thus leading to important spectroscopic changes.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Complexation of Chiral Oxirane Derivatives by an Enantiopure Cryptophane in Water

et al. 2018

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We show here that optically active cryptophane 1 bearing phenol functions can efficiently bind the two enantiomers of 2‐(chloromethyl)oxirane, ethyloxirane, and 2,2′‐bioxirane derivatives in aqueous solution. The binding process is characterized by high‐field 1H NMR signals that are specific to the encapsulated species. In all cases, an enantioselective effect was observed and a relationship between the molecular volume of the guest and the binding constant can be established, even though the flexibility of the guest molecule also seems to play a role. In this series, the 2,2′‐bioxirane guest is a particularly interesting example, because this compound possesses two stereogenic centers. Thus, in solution, three different pairs of enantiomers can be obtained in the presence of the optically active host 1. Electronic circular dichroism (ECD) spectroscopy has also been used to characterize these complexes; specific ECD spectra recorded in the 1Lb region were obtained for each diastereomer.

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Syn/Anti Pair of Triazole‐Bridged Cryptophanes: Synthesis, Characterization with Crystal Structures

Cited by 5 publications

References 39 publications

Desolvation Induced Conformational Transition in a Cryptophane Host: Crystal To Crystal Transformation

Desolvation Induced Conformational Transition in a Cryptophane Host: Crystal To Crystal Transformation

Synthesis of Cryptophanes: Recent Advances

Enantioselective Complexation of Chiral Oxirane Derivatives by an Enantiopure Cryptophane in Water

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