Phenol‐formaldehyde and allied resins VI: Rational synthesis of a ‘cyclic’ tetranuclear <i>p</i>‐cresol novolak

Hayes, B.; Hunter, R. F.

doi:10.1002/jctb.5010081107

Cited by 64 publications

(33 citation statements)

References 7 publications

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“…The process of ring inversion in biscal is now described using a schematic drawing of biscal as shown in Figure 4. As can be seen, the second calix [4] calix [4]arene undergoing ring inversion is the left hand calixarene of Figure 5 with the R substituent forming the right hand calixarene. It is clear that the four phenyl rings making up the calix [4]arene undergoing inversion are not equal.…”

Section: Resultsmentioning

confidence: 94%

“…Although most barriers are above the thermally averaged 0.5 kcal mol -1 expected to be required for accessibility at room temperature, in fact as explained earlier 7 , it is expected that biscal rings will readily interconvert between various conformers as for calix [4]arene. As such, it is perhaps not surprising to find that room temperature crystallisation of metal complexes is challenging, as stable conformations are required.…”

Section: Discussionmentioning

confidence: 96%

“…The biscalix [4]arene 13 (biscal) shown in Figure 2 represents an important addition to the calixarene family, with substitution occurring at one TBC4 methylene bridge to introduce an equivalent moiety. In this work we present a DFT analysis of the mechanism by which biscal undergoes annular inversion of one calixarene ring and is thus transformed from an anti-( In order to form polymetallic clusters involving octadentate ligation, via both TBC4 sub-unit lower rims, biscal must undergo a ring inversion of one calix [4]arene moiety.…”

Section: Figure 1 Tbc4 and Stable Conformationsmentioning

confidence: 99%

“…Gutsche's work into the synthesis of calix [4]arenes resulted in an explosion of variations within this basic framework, notably with a wide variety of substitutions at the para and phenolic oxygen positions, but also with modification at the methylene bridge 7,8,9 . As can be seen in Figure 1, four stable conformations of TBC4 are possible: cone, partial-cone, 1,2-alternate and 1,3-alternate. Interconversion between these conformers is achieved via annular rotation of the phenyl rings where the OH group passes through the TBC [4] sub-unit annulus.…”

Section: Introductionmentioning

confidence: 99%

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Elucidating the Ring Inversion Mechanism(s) for Biscalixarenes

2014

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Biscalix[4]arene can be constructed from a calix[4]arene by substitution of a methylene bridge hydrogen by another equivalent moiety. The use of biscalix[4]arenes (biscal) as precursors for the creation of new polymetallic clusters such as single-molecule magnets has potential in the fields of data storage and other applications. Polymetallic clusters involving biscal are expected to preferentially involve octadentate binding to two metal centers (one metal center per tetraphenolic pocket), requiring full inversion of one of the annular rings. In this work, we use density functional theory to establish the mechanism behind this process, considering the various energy pathways and providing insight into the preferred route to full and partial inversion. Fourteen possible pathways to full inversion are presented, including all transition states (up to seven per pathway). Subsequently, the lowest energy pathway to full inversion was found to have a barrier height of 19.31 kcal mol(-1). Solvent optimizations using PCM (with and without SMD) and CPCM solvent models suggest long-range solvent effects may be relatively unimportant in the inversion process. This study represents the first use of density functional theory to elucidate the entire potential energy surface, including barrier heights, of the ring inversion process of biscalix[4]arenes.

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Section: Resultsmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 96%

Section: Figure 1 Tbc4 and Stable Conformationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Elucidating the Ring Inversion Mechanism(s) for Biscalixarenes

2014

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“…In the presence of base, this protected cresol was reacted with formaldehyde and yields the hydroxymethylation product. Synthesis of many different kinds of ethers was developed by alkylation of calix [4]arenes (37,38). Dialkylations were carried out in different regiochemistries, either distally to give a 1,3-diether or proximally to give a 1,2-diether (37).…”

Section: Introductionmentioning

confidence: 99%

Application of nano-baskets in preconcentration of tetrahedral oxoanions in the produced water of oil wells

Bahram

Pourabdollah

2012

Supramolecular Chemistry

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This paper introduces a supramolecular-based microextraction technique and examines its ability in preconcentration of tetrahedral oxoanions in the produced water. Diacid p-tert-butylcalix[4]arene in the cone conformation was synthesised and used. The respective parameters including ligand concentration, volume of aqueous disperser, salt effect and extraction time were optimised. The linear range, detection limit (S/N ¼ 3) and precision (relative standard deviation, n ¼ 6) were determined to be in the range of 1.0 -280, 2.0-42.0 mg/l and 2.6-11.0%, respectively.

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Supramolecular Chemistry

Cragg¹

2006

Kirk-Othmer Encyclopedia of Chemical Technology

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Supramolecular chemistry has its origins in the supermolecule, a term used by Nobel Laureate Jean‐Marie Lehn from the early 1970s when referring to a well‐defined chemical species comprising several components. The realization that supermolecules could in turn form larger molecular assemblies led to the shift in emphasis from super‐ to supramolecular in the literature to more accurately describe the complexity of systems involved. Supramolecular chemistry has since advanced to include complexes between molecules with complementary binding sites (molecular recognition), multicomponent complexes (supramolecular assemblies), the programmed interactions between large molecular assemblies (molecular tectonics), and even the directed assembly of three‐dimensional solids (crystal engineering). This article sets out the concepts and aims of supramolecular chemistry, illustrates some of the early development in the field, considers the synthesis and structures of individual supramolecular synthons as well as supramolecular assemblies, and concludes with an assessment of current and anticipated applications in materials science, medicine, the interface with biology, molecular computing, nanomaterials, and nanomachines.

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Phenol‐formaldehyde and allied resins VI: Rational synthesis of a ‘cyclic’ tetranuclear p‐cresol novolak

Cited by 64 publications

References 7 publications

Elucidating the Ring Inversion Mechanism(s) for Biscalixarenes

Elucidating the Ring Inversion Mechanism(s) for Biscalixarenes

Application of nano-baskets in preconcentration of tetrahedral oxoanions in the produced water of oil wells

Supramolecular Chemistry

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