Hammett correlations ‘beyond the molecule’ 1

Ashton, Peter R.; Fyfe, Matthew C. T.; Hickingbottom, Sarah K.; Stoddart, J. Fraser; White, Andrew J. P.; Williams, David J.

doi:10.1039/a802406e

Cited by 110 publications

(86 citation statements)

References 34 publications

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“…Finally, K eff values for [2]rotaxanes containing pyridine or furan units are similar for each dumbbell-shaped ion and are comparable to the strengths of binding in CD 3 CN of disubstituted dibenzylammonium salts with the crown ethers DB24C8 [118,[196][197][198] and dipyridyl [24]crown-8 [199].…”

Section: Ammonium Ion Templated Synthesesmentioning

confidence: 72%

Templated Synthesis of Interlocked Molecules

Aricò

Badjić

Cantrill

et al. 2005

Topics in Current Chemistry

195

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Section: Ammonium Ion Templated Synthesesmentioning

confidence: 72%

Templated Synthesis of Interlocked Molecules

Aricò

Badjić

Cantrill

et al. 2005

Topics in Current Chemistry

195

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“…This reduced treading efficiency of 5 may be attributed to (i) a larger size (negative steric interaction with the bulky stopper) and, more likely, to (ii) the presence of the electron withdrawing CF 3 groups on the ring that render the oxygen atoms of the crown less prone to make effective [N + -H · · · O] hydrogen-bonding interactions. 21 …”

Section: Synthesis Of the Oriented Macrocylementioning

confidence: 99%

Towards the stereoselective synthesis of inherently chiral pseudorotaxanes

et al. 2006

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Herein is reported an investigation towards the stereoselective synthesis of inherently chiral pseudorotaxanes. Chiral ammonium threads were readily prepared in five steps from racemic or enantiopure (M or P) salts of di-n-propyl-1,13-dimethoxyquinacridinium cation. Their self-assembly with DB24C8 or disymmetrically oriented DB24C8F6 rings formed pseudorotaxanes as shown by 1 H and 19 F NMR spectroscopy as well as MS measurements. A determination of the association constants (K a ) was afforded. The crucial role played by the ammonium counter-ion in the threading process was further demonstrated as salts of TRISPHAT (tris(tetrachlorobenzenediolato)phosphate(V)) anion were quite more effective than their PF 6 − analogues (× 7.3). A general lack of diastereoselectivity (de ≤ 8%) was unfortunately observed.

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“…We have here a rarely noted supramolecular substituent effect [37] on pK a values, where the cation serves as the substituent. Physical organic chemistry usually deals with the effects of substituents which are covalently attached to the structure carrying the reactive site.…”

Section: Methodsmentioning

confidence: 99%

Modification of Fluorescent Photoinduced Electron Transfer (PET) Sensors/Switches To Produce Molecular Photo‐Ionic Triode Action

Huxley¹,

Schroeder²,

Gunaratne³

et al. 2014

Angewandte Chemie

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The fluorophore-spacer 1 -receptor 1 -spacer 2 -receptor 2 system (where receptor 2 alone is photoredox-inactive) shows ionically tunable proton-induced fluorescence off-on switching, which is reminiscent of thermionic triode behavior. This also represents a new extension to modular switch systems based on photoinduced electron transfer (PET) towards the emulation of analogue electronic devices.Fluorescent photoinduced electron transfer (PET) sensors/ switches [1][2][3][4] are a well-established application of molecular devices, to the point of real-life deployment worldwide in blood electrolyte diagnostics. [5][6][7][8] Important picosecond laser studies on fluorescent PET sensors/switches have demonstrated the transient existence of radical ion species, [9][10][11] and thus designers can proceed with confidence. As a result of their modular fluorophore-spacer-receptor construction, fluorescent PET systems are very amenable to modification in terms of the format, as well as in terms of the detailed functionalities. The latter approach has yielded many individual examples of sensors and switches based on fluorescence which target important analytes. [12][13][14][15] On the other hand, the former approach has the potential to set up new areas of endeavor and application, which is exploited here.The controllable quenching of molecular fluorescence [1,2] can be exploited to build switchable systems which emulate familiar electronic devices. Some of these molecular systems have unique applications which are inconvenient for their electronic counterparts, such as wireless operation in micrometric spaces. [16] The first molecular logic gate [17][18][19][20][21][22][23] 1 (an advanced molecular switch [24] ) was a fluorophore-spacer 1 -receptor 1 -spacer 2 -receptor 2 system, [25,26] where two photoinduced electron transfer (PET) [4, 27] channels arising from the two receptors were controlled by binding H + and Na + ions, respectively, and thus the fluorescence output corresponded to photo-ionic AND logic. Strong fluorescence emerges only when all PET processes are suppressed (Figure 1 a). [4] Related, but distinct, fluorophore-spacer 1 -receptor 1 -spacer 2 -receptor 2 systems, [28] where both receptors respond to H + ions, for example, 2, give rise to fluorescent off-on-off action, which can correspond to ternary logic behavior. [22] We now demonstrate aspects of molecular photo-ionic triode action for the first time by structurally mutating the fluorophore-spacer 1 -receptor 1 -spacer 2 -receptor 2 system 1 into a novel format exemplified by 3, where the convenient photoredox capability of receptor 2 is removed from 1 (Figure 1 b). Nearly 20 distinct formats of luminescent PET switching systems, each possessing its own defining features and applications, are known. [26] Fluorescence off-on switching is, therefore, controlled within 3 by selective ion binding of receptor 1 . This switching profile is influenced by the orthogonally selective ion binding of receptor 2 , which is forced into a secondary role...

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Hammett correlations ‘beyond the molecule’ 1

Cited by 110 publications

References 34 publications

Templated Synthesis of Interlocked Molecules

Templated Synthesis of Interlocked Molecules

Towards the stereoselective synthesis of inherently chiral pseudorotaxanes

Modification of Fluorescent Photoinduced Electron Transfer (PET) Sensors/Switches To Produce Molecular Photo‐Ionic Triode Action

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