From the Decks to the Bridges: Optoelectronics in [2.2]Paracyclophane Chemistry

Elacqua, Elizabeth; MacGillivray, Leonard R.

doi:10.1002/ejoc.201000930

Cited by 65 publications

(41 citation statements)

References 59 publications

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“…ROMP of pCpd was conducted under an inert nitrogen environment with the monomer (50 mg, 0.0637 mmol) dissolved in 1 mL of CDCl 3 and the initiator (Hoveyda-Grubbs II; 1.9 mg for 10mer) dissolved in 0.5 mL of CHCl 3 . 5 The solutions were combined and heated to 68 8C. The polymerization was monitored for completion using 1 H NMR spectroscopy (wherein a trace of the unreactive diene regioisomer was utilized as an internal standard).…”

Section: Ppv-pdmentioning

confidence: 99%

“…Bcps containing helical features, for instance, offer potential in applications such as chiroptical switching 1,2 and liquid crystals. 3,4 Bcps can be engineered via both noncovalent [5][6][7] and covalent strategies, both of which are modular and can afford polymeric scaffolds comprising multiple different polymer blocks within a single macromolecular species.…”

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confidence: 99%

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Coil‐helix and sheet‐helix block copolymers via macroinitiation from telechelic ROMP polymers

Elacqua

Croom

Lye

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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Coil-helix and sheet-helix block copolymers are synthesized by combining the ring-opening metathesis polymerization (ROMP) of norbornene or paracyclophanediene with the anionic polymerization of phenyl isocyanide. Key to the design is the use of an l-ethynyl palladium (II) functionalized chaintransfer agent (CTA) that can be exploited in a stepwise manner for the termination of ROMP and the initiation of the anionic polymerization. Both the coil-and sheet-macroinitiators, and the ensuing covalent block copolymers, are analyzed using 1 H NMR spectroscopy and gel-permeation chromatography. In all cases, the Pd-end group is maintained and all polymers demonstrate a monomodal distribution with dispersities ( -D) of 1.1-1.4. The resulting helix-coil and helix-sheet block copolymers formed by the macroinitiation route still demonstrate their intrinsic properties (fluorescence, preferential helixsense).

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Section: Ppv-pdmentioning

confidence: 99%

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confidence: 99%

Coil‐helix and sheet‐helix block copolymers via macroinitiation from telechelic ROMP polymers

Elacqua

Croom

Lye

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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“…To gain further insight into the FL properties of 1 BF 2 , we designed 2 BF 2 in which orbital overlap is fixed by the presence of the [2.2]paracyclophane moiety . In this effort, we evaluated the photophysical properties of 2 BF 2 , focusing particularly on the effects of solvents on FL.…”

Section: Introductionmentioning

confidence: 99%

“…[27] To gain further insight into the FL properties of 1BF 2 ,w ed esigned 2BF 2 in which orbital overlap is fixed by the presence of the [2.2]paracyclophane moiety. [28][29][30][31] In this effort, we evaluated the photophysical properties of 2BF 2 ,f ocusingp articularly on the effects of solvents on FL. The resultss how that, unlike 1BF 2 ,F Lf rom 2BF 2 is dramatically affected by the solvent polarity.I na ddition, we observed that the solvatofluorochromic properties of 2BF 2 enable it to serve as ah ighlys ensitive solventp olarity indicator, especially for low-polarity mixed solventsystems.…”

Section: Introductionmentioning

confidence: 99%

Remarkable Solvatofluorochromism of a [2.2]Paracyclophane‐Containing Organoboron Complex: A Large Stokes Shift Promoted by Excited State Intramolecular Charge Transfer

et al. 2017

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An organoboron complex containing a [2.2]paracyclophanyl group (2 BF2) exhibits remarkable solvatofluorochromism associated with a large Stokes shift. With increased solvent polarity, the fluorescence (FL) color of 2 BF2 changes from sky blue (λFL=485 nm in cyclohexane (c‐C6H12)) to orange (λFL=576 nm in CH3CN). This behavior derives from the intramolecular charge transfer (ICT) character of the excited state 2 BF2* in which the [2.2]paracyclophanyl group serves as the electron donor while the remaining 2 BF2 structure (apart from the sub‐benzene ring) functions as the electron acceptor. Wave deconvolution of FL spectra in a solvent mixture of CH2Cl2/c‐C6H12, and a plot of the FL emission energy versus the CH2Cl2/c‐C6H12 ratio, suggest that FL of 2 BF2 occurs from two types of 2 BF2* excited states. The results of DFT calculations support this explanation and further emphasize that the ICT character of 2 BF2* is derived from a large conformational change associated with the electron‐donating character of the [2.2]paracyclophanyl group. Moreover, the fact that 2 BF2 is more sensitive than Reichardt's dye to polarity changes in a low polarity CH2Cl2/c‐C6H12 solvent mixture is also of importance.

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“…ET and electronic coupling across p-stacked interfaces may be studied more easily in well-defined molecular systems in which the p-systems are fixed by linkers in a certain distance and orientation. Paracyclophanes (PCs) are particularly well suited for this purpose and have thus been employed in a variety of spectroscopic studies of ET characteristics, [13][14][15][16][17][18][19][20][21] as well as for conduction experiments. [22,23] In the latter case, Seferos et al have recently pointed out differences between different measurement procedures (e.g., STM vs. conductive AFM or cross-wire conduction experiments).…”

Section: Introductionmentioning

confidence: 99%

Electron transfer pathways in mixed‐valence paracyclophane‐bridged bis‐triarylamine radical cations

et al. 2015

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A series of paracyclophane (PC) bridged mixed-valence (MV) bis-triarylamine radical cations with different ([2.2], [3.3], [4.4]) linkers, with and without additional ethynyl spacers, have been studied by quantum-chemical calculations (BLYP35-D3/TZVP/COSMO) of ground-state structures, thermal electron-transfer barriers, hyperfine couplings, and lowest-lying excited states. Such PC-bridged MV systems are important intra-molecular model systems for inter-molecular electron transfer (ET) via π-stacked aromatics, since they allow enforcement of a more or less well-defined geometrical arrangement. Closely comparable ET barriers and electronic couplings for all [2.2] and [3.3] bridges are found for these class-II MV systems, irrespective of the use of pseudo-para and pseudo-meta connections. While the latter observation contradicts notions of quantum interference for off-resonant conduction through molecular wires, it agrees with the less intricate nodal structures of the highest occupied molecular orbitals. The ET in such MV systems may be more closely connected with hole conduction in the resonant regime. Computations on model cations, in which the [2.2] linkers have been truncated, confirm predominant through-space π-π electronic coupling. Systems with [4.4] PC bridges exhibit far more structural flexibility and concomitantly weaker electronic interactions between the redox centers.

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From the Decks to the Bridges: Optoelectronics in [2.2]Paracyclophane Chemistry

Cited by 65 publications

References 59 publications

Coil‐helix and sheet‐helix block copolymers via macroinitiation from telechelic ROMP polymers

Coil‐helix and sheet‐helix block copolymers via macroinitiation from telechelic ROMP polymers

Remarkable Solvatofluorochromism of a [2.2]Paracyclophane‐Containing Organoboron Complex: A Large Stokes Shift Promoted by Excited State Intramolecular Charge Transfer

Electron transfer pathways in mixed‐valence paracyclophane‐bridged bis‐triarylamine radical cations

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