Enforced Face-to-Face Stacking of Organic Semiconductor Building Blocks within Hydrogen-Bonded Molecular Cocrystals

Sokolov, Anatoliy N.; Friščić, Tomislav; MacGillivray, Leonard R.

doi:10.1021/ja057939a

Cited by 262 publications

(227 citation statements)

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“…The stacking can occur spontaneously without special substituents or approach directions, as in the case of neutral aromatic molecules (39). Closed-shell cation PAH dimers have optical properties that are markedly different from the monomers with very strong electronic transitions in the red and near-IR regions, as are required to explain the long-standing question of the ERE.…”

Section: Discussionmentioning

confidence: 99%

Charged polycyclic aromatic hydrocarbon clusters and the galactic extended red emission

Rhee

Lee²,

Gudipati³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

116

114

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The species responsible for the broad extended red emission (ERE), discovered in 1975 and now known to be widespread throughout the Galaxy, still is unidentified. Spanning the range from Ϸ540 to 900 nm, the ERE is a photoluminescent process associated with a wide variety of different interstellar environments. Over the years, a number of plausible candidates have been suggested, but subsequent observations ruled them out. The objects that present the ERE also emit the infrared features attributed to free polycyclic aromatic hydrocarbon (PAH) molecules, suggesting that closely related materials are plausible ERE carriers. Here, we show that the peculiar spectra and unique properties of closed-shell cationic PAH dimers satisfy the existing observational constraints and suggest that emission from mixtures of charged PAH clusters accounts for much of the ERE. This work provides a view into the structures, stabilities, abundances, and ionization balance of PAH-related species in the emission zones, which, in turn, reflects physical conditions in the emission zones and sheds fundamental light on the nanoscale processes involved in carbon-particle nucleation and growth and carbonaceous dust evolution in the interstellar medium.dimer ͉ excited state ͉ interstellar medium ͉ nanoparticles T he extended red emission (ERE) was discovered in 1975 by Cohen et al. (1) in the peculiar object known as the Red Rectangle. Subsequent observations have shown that it is a widespread interstellar photoluminescent phenomenon. Witt and coworkers established that the ERE is associated with reflection nebulae (2, 3), carbon-rich planetary nebulae (4), and the interstellar medium of the Galaxy (5), whereas Darbon, Perrin, Sivan, and coworkers have detected the ERE in galactic HII regions and other galaxies (6-8). A detailed review can be found elsewhere (9).The ERE is a broad emission band starting near 540 nm that extends into the near infrared (IR). For most objects, the peak wavelength varies between 600 and 700 nm (3), although in the HII region of the Orion nebula, the band seems to peak near 800 nm (8). These variations are thought to arise from modest changes in chemical make-up and differing radiation fields and not from fundamental changes in the nature of the carrier. In some cases, structure appears superposed on the band (10, 11). Over the years a number of possible explanations have been suggested, including photoluminescence from species such as neutral polycyclic aromatic hydrocarbon (PAH) molecules (12), organic residues (13), neutral PAH clusters (14), hydrogenated amorphous carbon particles (15, 16), and silicon nanoparticles (17). Although a carbon-rich carrier was implicated by cosmic abundance constraints, all of these materials have been found wanting in light of subsequent observations. The case for each of these suggestions and the observational difficulties they encounter are summarized nicely by Witt et al. (18). Recently, observational constraints have been determined that are especially important in revealing t...

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Section: Discussionmentioning

confidence: 99%

Charged polycyclic aromatic hydrocarbon clusters and the galactic extended red emission

Rhee

Lee²,

Gudipati³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

116

114

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“…Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved May 19, 2011 (received for review March 19, 2011) Treatment of an achiral molecular ladder of C 2h symmetry composed of five edge-sharing cyclobutane rings, or a [5]-ladderane, with acid results in cis-to trans-isomerization of end pyridyl groups. Solution NMR spectroscopy and quantum chemical calculations support the isomerization to generate two diastereomers.…”

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confidence: 99%

“…supramolecular synthesis | solid-state reactivity | hydrogen bonding C rystal engineering involves the rational design of solids with predictable and/or tunable properties (1,2). During the past two decades, crystal engineering has undergone remarkable growth with applications in areas such as catalysis (3), energy storage (4), electronics (5,6), and pharmaceutics (7,8). A burgeoning area in the field of crystal engineering involves the design and properties of cocrystals (7)(8)(9)(10)(11).…”

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confidence: 99%

“…The ladderane lipids serve a structural role of providing extraordinary rigidity to internal membrane components. More specifically, we have shown that a CCF based on 1,3-dihydroxybenzene, or resorcinol (res), acts as a template to assemble polyenes via hydrogen bonds into supramolecular assemblies for [2 þ 2] photocycloadditions that generate [3]and [5]-ladderanes (12). Cocrystallization of 5-methoxyresorcinol (5-OMe-res) with either an all-trans-4-pyridyl-substituted 1,4-butadiene or 1,6-hexatriene yielded assemblies of composition 2ðtemplateÞ · 2ðpolyeneÞ.…”

mentioning

confidence: 99%

“…Our interests lie in using ladderanes synthesized in the solid state as precursors to the natural lipids. During experiments to treat 4-pyr- [5]-lad with acid, the terminal pyridyl groups were determined to undergo a cis-to trans-isomerization that generates two isomers. Multidimensional solution NMR spectroscopy-a tool commonly used to elucidate the structures of organic molecules-supported the isomerization, along with quantum chemical calculations, to produce two diastereomers; namely, achiral 1a and chiral 1b (Scheme 2).…”

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confidence: 99%

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Crystal engineering rescues a solution organic synthesis in a cocrystallization that confirms the configuration of a molecular ladder

Atkinson

Mariappan

Bučar

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Treatment of an achiral molecular ladder of C 2h symmetry composed of five edge-sharing cyclobutane rings, or a [5]-ladderane, with acid results in cis-to trans-isomerization of end pyridyl groups. Solution NMR spectroscopy and quantum chemical calculations support the isomerization to generate two diastereomers. The NMR data, however, could not lead to unambiguous configurational assignments of the two isomers. Single-crystal X-ray diffraction was employed to determine each configuration. One isomer readily crystallized as a pure form and X-ray diffraction revealed the molecule as being achiral based on C i symmetry. The second isomer resisted crystallization under a variety of conditions. Consequently, a strategy based on a cocrystallization was developed to generate single crystals of the second isomer. Cocrystallization of the isomer with a carboxylic acid readily afforded single crystals that confirmed a chiral ladderane based on C 2 symmetry. The chiral ladderane and acid self-assembled to generate a five-component hydrogen-bonded complex that packs to form large solvent-filled homochiral channels of nanometer-scale dimensions. Whereas cocrystallizations are frequently applied to structure determinations of proteins, our study represents the first application of a cocrystallization to confirm the relative configuration of a small-molecule diastereomer generated in a solution-phase organic synthesis. supramolecular synthesis | solid-state reactivity | hydrogen bonding

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Cocrystals: Synthesis, Structure, and Applications

Aakeröy

Chopade

2012

Supramolecular Chemistry

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The crystal structure of a compound, the 3D orientation and organization of molecules in a highly regular manner, ultimately determines most of the fundamental physical properties of that particular material, for example, thermal stability, hygroscopicity, conductivity, and mechanical strength. Consequently, an ability to control and change the crystalline environment of a material without altering the molecular properties would be of enormous significance to both manufacturers and consumers of solid specialty chemicals such as pharmaceuticals, pigments, energetic materials, toxins, foodstuff, and detergents. Preparation of cocrystals—homogeneous crystalline solids composed of different molecular building blocks—offers an additional path for incorporating functional molecules, active ingredients, within a crystalline casing, but the synthetic challenges associated with supramolecular synthesis are numerous and nontrivial. This chapter describes several strategies for the assembly of cocrystals using hydrogen bonds and halogen bonds and provides a more in‐depth examination of how the electrostatic charge on individual attempts can be used to control efficiency and selectivity of supramolecular synthesis. Finally, a few examples of applications of cocrystals in pharmaceutical sciences are discussed.

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Enforced Face-to-Face Stacking of Organic Semiconductor Building Blocks within Hydrogen-Bonded Molecular Cocrystals

Abstract: We report a method to enforce face-to-face stacking of the aromatic rings of organic semiconductor molecules in the solid state that employs bifunctional hydrogen-bond donors, in the form of semiconductor cocrystal formers, to align semiconductor building blocks.

Cited by 262 publications

References 19 publications

Charged polycyclic aromatic hydrocarbon clusters and the galactic extended red emission

Charged polycyclic aromatic hydrocarbon clusters and the galactic extended red emission

Crystal engineering rescues a solution organic synthesis in a cocrystallization that confirms the configuration of a molecular ladder

Cocrystals: Synthesis, Structure, and Applications

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