Computational Insight to Improve the Thermal Isomerisation Performance of Overcrowded Alkene‐Based Molecular Motors through Structural Redesign

Oruganti, Baswanth; Wang, Jun; Durbeej, Bo

doi:10.1002/cphc.201600766

Cited by 15 publications

(23 citation statements)

References 64 publications

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“…Notably, the calculations also identify a concerted, single-step mechanism that proceeds without passing through an intermediate. [70] For 7a and 7b, the concerted mechanism is not kinetically competitive with the two-step mechanism, whose ratedetermining free-energy barriers amount to 18 (7a) and 41 kJ mol 21 (7b). For 7c, the two mechanisms have similar barriers of 23-24 kJ mol 21 .…”

Section: And (P)-unstable-e Species Formed By Photoisomerizations Of mentioning

confidence: 95%

“…To this end, the structurally redesigned motors 7a-7c shown in Figure 7 were subjected to DFT calculations of the type outlined above. [70] In these motors, the cyclopenta[a]napthalenylidene and thioxanthene moieties of 2 are replaced with an indanylidene rotator and a cyclohexadiene (7a), pyran (7b), or thiopyran (7c) stator, respectively. Importantly, through multi-reference quantum chemical modeling of the E !…”

Section: Other Mother Designs: 3608 Rotation Through Fewer Stepsmentioning

confidence: 99%

“…E photoisomerizations of 7a-7c around the central olefinic bond, it was firstly verified that these processes produce 3608 unidirectional rotary motion, and that each photoisomerization must be followed by a thermal isomerization to complete a full rotary cycle. [70] As illustrated in Figure 8, which summarizes the DFT calculations, the thermal isomerizations of 7a-7c start from the (P)-unstable-Z…”

Section: Other Mother Designs: 3608 Rotation Through Fewer Stepsmentioning

confidence: 99%

“…Although the barriers vary quite a lot between the three motors, which in part can be explained by the differences in size of the stator bridging atom X (for example, the isomerizations of 7c are more facile than those of 7b thanks to a favorable steric destabilization of the (P)-unstable-Z and (P)-unstable-E reactants by the larger sulfur bridging atom of 7c), [70] the rate-determining barriers for 7a and 7c are up to 25 kJ mol 21 smaller than the 43 kJ mol 21 barrier attributed to reference motor 2 by the same exact level of DFT calculations. All in all, then, the computational prediction that systems 7a-7c hold certain advantages over second-generation overcrowded alkenes appears worthwhile to test in the future experimental development of improved rotary motors.…”

Section: And (P)-unstable-e Species Formed By Photoisomerizations Of mentioning

confidence: 99%

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Quantum chemical design of rotary molecular motors

Oruganti

Wang

Durbeej

2017

Int J of Quantum Chemistry

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This tutorial review describes how recent quantum chemical calculations and non-adiabatic molecular dynamics simulations have provided valuable guidelines and insights for the design of more powerful synthetic rotary molecular motors. Following a brief overview of the various types of rotary motors synthesized to date, we present computationally identified steric and electronic approaches to significantly reduce the free-energy barriers of the critical thermal isomerization steps of chiral overcrowded alkenes, a main class of motors whose potential for many different kinds of applications is well documented. Furthermore, we describe how computational research in this field has provided new motor designs that differ from overcrowded alkenes by either (1) completing a full 3608 rotation through fewer steps, (2) exhibiting more efficient photochemical steps, or (3) requiring fewer chiral features for their function, including a design that even in the absence of a stereocenter achieves unidirectional rotary motion from two Z/E photoisomerizations alone.chirality, molecular motors, non-adiabatic molecular dynamics, photoisomerization, steric interactions | I N TR ODU C TI ONIn this tutorial review, we give an account of how quantum chemical research has contributed to advance the field of artificial molecular machines.This field [1][2][3][4][5][6][7][8][9][10][11] is devoted to the fabrication of molecular systems capable of performing the same type of machine-like functions that Nature-made protein complexes carry out in order to, among other things, propel cells, store energy in cells, equip cells with transport systems, and generate biomechanical forces. [12][13][14] Although artificial molecular machines are yet to make an impact on our everyday lives, the field is currently undergoing a rapid expansion both in terms of what man-made molecules can accomplish and the areas of expertise of the scientists drawn to the field. In many ways, this development, envisioned already in 1959 by Richard Feynman in his prophetic "There's Plenty of Room at the Bottom" lecture, [15] is testament to the groundbreaking work on the design and synthesis of molecular machines [16][17][18][19][20][21][22][23][24][25] for which Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard (Ben) L. Feringa were awarded the Nobel Prize in Chemistry 2016.While a molecular machine can be defined as "an assembly of a discrete number of molecular components designed to perform mechanical-like movements (output) as a consequence of appropriate external stimuli (input)," [2] this tutorial review focuses on the subset of such systems known as molecular motors. Loosely speaking, molecular motors are molecules that can produce net work by absorbing external energy and converting the energy into directed (non-random) mechanical motion in a controllable fashion. The ability to produce net work is the distinguishing feature of molecular motors vis-a-vis molecular switches, the latter of which sustain back-and-forth motion but not the continuous m...

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Section: And (P)-unstable-e Species Formed By Photoisomerizations Of mentioning

confidence: 95%

Section: Other Mother Designs: 3608 Rotation Through Fewer Stepsmentioning

confidence: 99%

Section: Other Mother Designs: 3608 Rotation Through Fewer Stepsmentioning

confidence: 99%

Section: And (P)-unstable-e Species Formed By Photoisomerizations Of mentioning

confidence: 99%

See 2 more Smart Citations

Quantum chemical design of rotary molecular motors

Oruganti

Wang

Durbeej

2017

Int J of Quantum Chemistry

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“…Against this background, considerable efforts have been devoted both to finding ways to accelerate the thermal steps of overcrowded‐alkene motors and to put forth alternative light‐driven motor designs that require no thermal steps to complete a full 360° rotation . Furthermore, progress has also been made in the design of new motors with photoisomerization QYs that are less hampered by pyramidalization at the isomerizing bond than overcrowded‐alkene motors .…”

Section: Introductionmentioning

confidence: 99%

Toward Fast and Efficient Visible‐Light‐Driven Molecular Motors: A Minimal Design

Wang

Durbeej

2018

ChemistryOpen

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A key goal in the development of light‐driven rotary molecular motors is to facilitate their usage in biology and medicine by shifting the required irradiation wavelengths from the UV regime to the nondestructive visible regime. Although some progress has been made toward this goal, most available visible‐light‐driven motors either have relatively low quantum yields or require that thermal steps follow the photoisomerizations that underlie the rotary motion. Here, a minimal design for visible‐light‐driven motors without these drawbacks is presented and evaluated on the basis of state‐of‐the‐art quantum chemical calculations and molecular dynamics simulations. The design, featuring dihydropyridinium and cyclohexenylidene motifs and comprising only five conjugated double bonds, is found to produce a full 360° rotation through fast photoisomerizations (excited‐state lifetimes of ≈170–250 fs) powered by photons with energies well below 3 eV.

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Molecular Photoswitching Aided by Excited‐State Aromaticity

2018

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Central to the development of optoelectronic devices is the availability of efficient synthetic molecular photoswitches, the design of which is an arena where the evolving concept of excited‐state aromaticity (ESA) is yet to make a big impact. The aim of this minireview is to illustrate the potential of this concept to become a key tool for the future design of photoswitches. The paper starts with a discussion of challenges facing the use of photoswitches for applications and continues with an account of how the ESA concept has progressed since its inception. Then, following some brief remarks on computational modeling of photoswitches and ESA, the paper describes two different approaches to improve the quantum yields and response times of switches driven by E/Z photoisomerization or photoinduced H‐atom/proton transfer reactions through simple ESA considerations. It is our hope that these approaches, verified by quantum chemical calculations and molecular dynamics simulations, will help stimulate the application of the ESA concept as a general tool for designing more efficient photoswitches and other functional molecules used in optoelectronic devices.

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Computational Insight to Improve the Thermal Isomerisation Performance of Overcrowded Alkene‐Based Molecular Motors through Structural Redesign

Cited by 15 publications

References 64 publications

Quantum chemical design of rotary molecular motors

Quantum chemical design of rotary molecular motors

Toward Fast and Efficient Visible‐Light‐Driven Molecular Motors: A Minimal Design

Molecular Photoswitching Aided by Excited‐State Aromaticity

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