Photomechanical molecular crystals and nanowire assemblies based on the [2+2] photodimerization of a phenylbutadiene derivative

Tong, Fei; Xu, Wenwen; Guo, Tianyi; Lui, Brandon F.; Hayward, Ryan C.; Palffy‐Muhoray, Peter; Al‐Kaysi, Rabih O.; Bardeen, Christopher J.

doi:10.1039/c9tc06946a

“…1,[5][6][7] A new class of macroscopic crystals also known as "soft crystals" exhibit mechanical movements induced by pressure, heat, and light which often results in hopping, splitting, bending, curling, coiling, twisting, swimming of the crystals. 1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] With the upsurge of dynamic crystals, several examples of mechanically flexible crystals have been reported in the literature showing elastic and plastic deformation upon the application of an external force. [27][28][29][30][31][32][33][34] Apart from actuation by mechanical force, photomechanical actuation is of great advantage due to its remotely controlled process.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Bending and Modulation of Photoactuation Properties in a One-Dimensional Pb(II) Coordination Polymer

Rath

¹

,

Vittal

²

2021

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With emergent research on stimuli responsive materials, dynamic crystals are at the forefront of investigation.However, research on the mechanical properties of coordination polymers (CPs) is still in its infancy. Elastic deformation induced by pressure and photoactuation are rare occurrences in CPs, let alone their combination in a single CP. Here, we report a one-dimensional (1D) CP comprising PbBr2 chains with 3-fluoro-4'-styrylpyridine arms showing excellent elasticity and photomechanical properties. A slender crystal can be bent to make a circle and write different shapes with restoration of original shape upon removal of the applied force. In addition, photomechanical properties triggered by [2+2] cycloaddition of the olefinic ligand can be modulated easily by variation of the crystal sizes. Crystals with bigger width show destructive photosalient effects while the smaller ones show plastic deformation like bending, twisting, curling etc. upon UV irradiation. This example provides avenue for designing CPs for multi-stimuli responsive actuating properties. File list (12) download file view on ChemRxiv Rath et al. Manuscript.pdf (842.43 KiB) download file view on ChemRxiv Rath et al. Supp Info.pdf (1.06 MiB) download file view on ChemRxiv Video SV1_Elastic bending.mp4 (4.64 MiB) download file view on ChemRxiv Video SV2_Mechanical bending.mp4 (2.26 MiB) download file view on ChemRxiv Video SV3_Photosalient effects.mp4 (5.24 MiB) download file view on ChemRxiv Video SV4_Photoinduced bending.mp4 (3.64 MiB) download file view on ChemRxiv Video SV5_Light direction dependant bending.mp4 (4.21 MiB) download file view on ChemRxiv Video SV6_Photoinduced splitting and twisting.mp4 (2.95 MiB)

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“…A bunch of fiber-like crystals placed over one another immediately curled and intertwined together upon UV irradiation to form tangled bunch of fibers (Figure S13, Video SV9). Curling of crystals have been studied in organic crystals 17,43,49,50 and no such photomechanical behavior has been reported in CPs. Transduction of energy for performing observable work is of great importance for actuating materials.…”

Section: Resultsmentioning

confidence: 99%

“…1,[5][6][7] A new class of macroscopic crystals also known as "soft crystals" exhibit mechanical movements induced by pressure, heat, and light which often results in hopping, splitting, bending, curling, coiling, twisting, swimming of the crystals. 1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] With the upsurge of dynamic crystals, several examples of mechanically flexible crystals have been reported in the literature showing elastic and plastic deformation upon the application of an external force. [27][28][29][30][31][32][33][34] Apart from actuation by mechanical force, photomechanical actuation is of great advantage due to its remotely controlled process.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Bending and Modulation of Photoactuation Properties in a One-Dimensional Pb(II) Coordination Polymer

Rath¹,

Vittal²

2021

Preprint

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With emergent research on stimuli responsive materials, dynamic crystals are at the forefront of investigation. However, research on the mechanical properties of coordination polymers (CPs) is still in its infancy. Elastic deformation induced by pressure and photoactuation are rare occurrences in CPs, let alone their combination in a single CP. Here, we report a one-dimensional (1D) CP comprising PbBr2 chains with 3-fluoro-4’-styrylpyridine arms showing excellent elasticity and photomechanical properties. A slender crystal can be bent to make a circle and write different shapes with restoration of original shape upon removal of the applied force. In addition, photomechanical properties triggered by [2+2] cycloaddition of the olefinic ligand can be modulated easily by variation of the crystal sizes. Crystals with bigger width show destructive photosalient effects while the smaller ones show plastic deformation like bending, twisting, curling etc. upon UV irradiation. This example provides avenue for designing CPs for multi-stimuli responsive actuating properties.

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“…At the molecular level (requirement 1), we have recently developed aP-type photoisomerization system based on the anthracene derivative (E)-DVAM,which undergoes an E-Z photoisomerization in both solution and in the crystal form. [32] Requirement 2isfulfilled because the crystal packing in both E and Z forms prevents the [2+ +2] and [4+ +4] bimolecular photocycloaddition reactions seen in other photoactive anthracene crystals [33][34][35] while allowing the unimolecular isomerization to proceed. Nanowires and microcrystals could bend and actuate reversibly when subjected to visible and UV light.…”

Section: Resultsmentioning

confidence: 99%

Light‐Powered Autonomous Flagella‐Like Motion of Molecular Crystal Microwires

Tong

¹

,

Kitagawa

²

,

Bushnak

³

et al. 2020

Self Cite

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The ability to exhibit life‐like oscillatory motion fueled by light represents a new capability for stimuli‐responsive materials. Although this capability has been demonstrated in soft materials like polymers, it has never been observed in molecular crystals, which are not generally regarded as dynamic objects. In this work, it is shown that molecular crystalline microwires composed of (Z)‐2‐(3‐(anthracen‐9‐yl)allylidene)malononitrile ((Z)‐DVAM) can be continuously actuated when exposed to a combination of ultraviolet and visible light. The photo‐induced motion mimics the oscillatory behavior of biological flagella and enables propagation of microwires across a surface and through liquids, with translational speeds up to 7 μm s−1. This is the first example of molecular crystals that show complex oscillatory behavior under continuous irradiation. A model that relates the rotation of the transition dipole moment between reversible E→Z photoisomerization to the microscopic torque can qualitatively reproduce how the rotational frequency depends on light intensity and polarization.

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Photomechanical molecular crystals and nanowire assemblies based on the [2+2] photodimerization of a phenylbutadiene derivative

Abstract: Crystalline (E)-4-fluoro-cinnamaldehyde malononitrile undergoes a [2+2] photocycloaddition, leading to a robust photomechanical response and improved force generation by nanowire ceramic composites.

Cited by 66 publications

References 47 publications

Mechanical Bending and Modulation of Photoactuation Properties in a One-Dimensional Pb(II) Coordination Polymer

Mechanical Bending and Modulation of Photoactuation Properties in a One-Dimensional Pb(II) Coordination Polymer

Mechanical Bending and Modulation of Photoactuation Properties in a One-Dimensional Pb(II) Coordination Polymer

Light‐Powered Autonomous Flagella‐Like Motion of Molecular Crystal Microwires

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