Directed polymorphism and mechanofluorochromism of conjugated materials through weak non-covalent control

Sharber, Seth A.; Mann, Arielle; Shih, Kuo‐Chih; Mullin, William J.; Nieh, Mu‐Ping; Thomas, Samuel W.

doi:10.1039/c9tc01301f

Cited by 30 publications

(22 citation statements)

References 67 publications

(90 reference statements)

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“…We further showed how competitive interactions in PE structures can tailor both their optical properties in solids and their MFC response. A series of ester-terminated PEs exhibited polymorphism that strongly depended on alkyl chain length, where the prevalence for polymorph appearance could be modulated via competition between interactions of alkyl chains and ArF–ArH stacking . More surprisingly, we found that twisting can depend on the regiochemistry of fluorine substitution of the ArF rings, with solids of side chain regioisomers exhibiting divergent optical properties.…”

Section: Interactions Of Aromatic Rings: Tunable Stacking and Dynamic...mentioning

confidence: 73%

“…A series of ester-terminated PEs exhibited polymorphism that strongly depended on alkyl chain length, where the prevalence for polymorph appearance could be modulated via competition between interactions of alkyl chains and ArF−ArH stacking. 203 More surprisingly, we found that twisting can depend on the regiochemistry of fluorine substitution of the ArF rings, with solids of side chain regioisomers exhibiting divergent optical properties. While an anisyl-terminated PE with 2,4,6-trifluorinated side chains exhibited blue fluorescent films and a twisted, nonaggregated crystal structure, a 2,3,6-trifluorinated analog exhibited yellow emission in solidsa fluorescence shift of 136 nmwith a representative crystal structure showing coplanar and aggregated PEs.…”

Section: ■ Halogen-bonding Interactions: 2dmentioning

confidence: 75%

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Bridging the Void: Halogen Bonding and Aromatic Interactions to Program Luminescence and Electronic Properties of π-Conjugated Materials in the Solid State

2021

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π-Conjugated materials are promising candidates for emerging organic optoelectronic devices empowered by molecular design. The unsolved challenges of predicting and controlling their packing as solids, central to their properties and performance, currently limits their practical application. As noncovalent interactions drive packing, control over such interactions are critical to bridging from chemical structure to functional properties. In molecular crystals, halogen bonding and interactions of aromatic rings have emerged as versatile tools for noncovalent control with tailored luminescence and electronic properties. Here, we describe how the interplay of these directional and tunable interactions can engineer properties, including stimuli-responsive behavior. Halogen bonding can provide robust designs for directing 2D molecular assembly, whereas the intentional interactions of aromatic rings can yield metastable, switchable packing modes, as well as programmed stacking between layers of chromophores. Examples, herein, demonstrate clear relationships between assembly by design and resulting solid-state properties, and strategies presented offer guidance for future designs of π-conjugated molecular materials using specific aromatic interactions and halogen bonding.

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Section: Interactions Of Aromatic Rings: Tunable Stacking and Dynamic...mentioning

confidence: 73%

Section: ■ Halogen-bonding Interactions: 2dmentioning

confidence: 75%

Bridging the Void: Halogen Bonding and Aromatic Interactions to Program Luminescence and Electronic Properties of π-Conjugated Materials in the Solid State

2021

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“…As they are not coupled to the conjugated system, incorporating directional interactions into side chains enables structural control that is orthogonal to the function of the main chain and broadly applicable for many classes of main chain structures. − Analogous to the design in Chart , our group’s previous work has demonstrated side chain engineering for guiding optical and responsive properties in phenylene-ethynylenes (PEs) via electron-poor fluoroarene pendants that cofacially stack with arenes in the PE chromophore (ArF–ArH interactions). − This robust aromatic stacking interaction is useful in a variety of contexts to direct molecular packing. − To accommodate these interactions, the PE linkages twist out of coplanarity by at least 55°, reducing conjugation. In addition, these ArF–ArH interactions insulate the PE chromophores from each other by blocking regions of overlap that are otherwise required for through-space coupling.…”

Section: Introductionmentioning

confidence: 99%

Side Chain Regioisomers that Dictate Optical Properties and Mechanofluorochromism through Crystal Packing

Sharber

Thomas

2020

Chem. Mater.

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Designing strong interactions into π-conjugated materials can direct their typically uncontrolled molecular packing and is an important strategy toward tuning their technologically relevant properties in the solid state. Here we demonstrate unconventional control over solid-state fluorescence and mechanofluorochromism (MFC) through regiochemical substitutions in side chains of 12 three-ring phenylene ethynylenes (PEs) that employ fluoroarene–arene (ArF–ArH) interactions between tetrafluoro ArF pendants and PE main chains to direct crystal packing, with single-atom variations of the lone proton in ArF pendants between 4-hydro, 5-hydro, and 6-hydro substitution yielding in two cases dramatically different fluorescence and MFC behavior. X-ray crystal structures reveal key intermolecular interactions of ArF rings, including their lone protons, which vary as a function of substitution pattern and contribute to optical properties in solids. Rarely reported, particularly with such dramatic results, this systematic study on regiochemical effects over solid-state properties demonstrates the versatility of using discrete, directional interactions of side chains for noncovalent control in conjugated materials.

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“…82 Little was known about such relationship before this study. 83 Specifically, derivatives 35b and 35c crystalized as plate-like crystals and exhibited MCL behaviors. On the other hand, the emission color of needle-like crystals of 35dg remained unchanged after grinding.…”

Section: Strategies To Controlling the MCL Propertiesmentioning

confidence: 99%

Recent Advances in Mechanochromic Luminescence of Organic Crystalline Compounds

Ito

2020

Chemistry Letters

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Suguru Ito received his Ph.D. degree from Yokohama National University in 2011 under the supervision of Prof. Masatoshi Asami. After postdoctoral research at Tokyo Institute of Technology under Prof. Nobuharu Iwasawa, he was appointed as an assistant professor at Yokohama National University in 2013. In 2017, he became an associate professor at the same university. His research interest is centered on the creation of functional organic molecules such as organic fluorophores and chiral host compounds.

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Directed polymorphism and mechanofluorochromism of conjugated materials through weak non-covalent control

Abstract: Understanding and manipulating crystal polymorphism can provide novel strategies for materials discovery in organic optoelectronics.

Cited by 30 publications

References 67 publications

Bridging the Void: Halogen Bonding and Aromatic Interactions to Program Luminescence and Electronic Properties of π-Conjugated Materials in the Solid State

Bridging the Void: Halogen Bonding and Aromatic Interactions to Program Luminescence and Electronic Properties of π-Conjugated Materials in the Solid State

Side Chain Regioisomers that Dictate Optical Properties and Mechanofluorochromism through Crystal Packing

Recent Advances in Mechanochromic Luminescence of Organic Crystalline Compounds

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