Allosteric Regulation of the Rotational Speed in a Light-Driven Molecular Motor

Faulkner, Adele; Leeuwen, Thomas Van; Feringa, Ben L.; Wezenberg, Sander J.

doi:10.1021/jacs.6b06467

Cited by 88 publications

(81 citation statements)

References 65 publications

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“…[21,26] Since it was immediately recognized that the rate-limiting steps of the rotary cycles of 1 and other overcrowded alkenes are primarily the thermal steps, much experimental work was in the subsequent years and continuously up until today devoted to accelerating these particular steps. [25][26][27][28][50][51][52][53][54][55][56] Encouragingly, this work produced many powerful secondgeneration overcrowded alkenes. [25,27,28] Paralleling the experimental efforts, a series of systematic quantum chemical studies revealed a number of ways to further lower the thermal free-energy barriers of the second-generation motors, [57][58][59] that we now turn to discussing.…”

Section: Overcrowded-alkene Motorsmentioning

confidence: 96%

“…While many experimental and computational efforts have been made to improve the thermal isomerization performance of overcrowded-alkene motors, [25][26][27][28][50][51][52][53][54][55][56][57][58][59] it is also important to explore ways to control and modulate their photochemical steps [67][68][69] or the possibility to design new classes of rotary motors whose photochemical steps proceed more efficiently. Through NAMD simulations, [49] it has been inferred that the photoisomerization QYs of overcrowded alkenes are limited (to 0.2-0.3 [68,73] ) by the requirement that the torsional motion around the central olefinic bond in the photoactive first excited singlet state (S 1 ) is coupled to a substantial pyramidalization of one of the carbon atoms, or else the conical intersection (CI) seam with the ground state (S 0 ) cannot be reached.…”

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: Overcrowded-alkene Motorsmentioning

confidence: 96%

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

confidence: 99%

Quantum chemical design of rotary molecular motors

Oruganti

Wang

Durbeej

2017

Int J of Quantum Chemistry

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“…[1][2][3] Fundamental developments have discovered fascinating phenomena and enabled a wealth of applications in the gas phase, [4][5][6][7][8] in solution, 4,[9][10][11] in crystals, 4,12 on surfaces, [4][5][6][13][14][15] and in biosystems. 16 Here we use a molecular model rotor to demonstrate the way from molecular quantum dynamics to explicitly time dependent statistical thermodynamics.…”

mentioning

confidence: 99%

“…+ with inner triangular wheel rotating in outer pseudo-rotating bearing (schematic). Clockwise and anti-clockwise tunneling from the global minimum GM 16 to the neighbors GM 15 and GM 17 , respectively (left), and then sequentially to GM 14 , GM 13 , GM 12 , GM 11 , etc, and simultaneously also to GM 18 , GM 19 , GM 20 , GM 21 , etc (right). Subsequent tunneling tends to populate all GMs, see Fig.…”

mentioning

confidence: 99%

From coherent quasi-irreversible quantum dynamics towards the second law of thermodynamics: The model boron rotor B13+

2018

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The planar boron cluster B13+ provides a model to investigate the microscopic origin of the second law of thermodynamics in a small system. It is a molecular rotor with an inner wheel that rotates in an outer bearing. The cyclic reaction path of B13+ passes along thirty equivalent global minimum structures (GMi, i = 1, 2, ..., 30). The GMs are embedded in a cyclic thirty-well potential. They are separated by thirty equivalent transition states with potential barrier Vb. If the boron rotor B13+ is prepared initially in one of the thirty GMs, with energy below Vb, then it tunnels sequentially to its nearest, next-nearest etc. neighbors (520 fs per step) such that all the other GMs get populated. As a consequence, the entropy of occupying the GMs takes about 6 ps to increases from zero to a value close to the maximum value for equi-distribution. Perfect recurrences are practically not observable.

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“…A major experimental effort has therefore been invested to improve the rates and efficiencies of overcrowded alkene-based molecular motors. 9,10,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] In this regard, computational methods are particularly useful as they can provide detailed insights into the mechanisms and dynamics of the chemical reactions that produce the rotary motion. Such insights may not be easily obtained by experimental techniques, because of the difficulties associated with detecting transient species such as reactive intermediates and transition structures (TSs) or measuring the timescales of ultrafast processes.…”

Section: Introductionmentioning

confidence: 99%

Computational Design of Molecular Motors and Excited-State Studies of Organic Chromophores

Oruganti¹

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This thesis presents computational quantum chemical studies of molecular motors and excited electronic states of organic chromophores.The first and major part of the thesis is concerned with the design of lightdriven rotary molecular motors. These are molecules that absorb light energy and convert it into 360° unidirectional rotary motion around a double bond connecting two molecular halves. In order to facilitate potential applications of molecular motors in nanotechnology, such as in molecular transport or in development of materials with photo-controllable properties, it is critical to optimize the rates and efficiencies of the chemical reactions that produce the rotary motion. To this end, computational methods are in this thesis used to study two different classes of molecular motors.The first class encompasses the sterically overcrowded alkenes developed by Ben Feringa, co-recipient of the 2016 Nobel Prize in Chemistry. The rotary cycles of these motors involve two photoisomerization and two thermal isomerization steps, where the latter are the ones that limit the attainable rotational frequencies. In the thesis, several new motors of this type are proposed by identifying steric, electronic and conformational approaches to accelerate the thermal isomerizations. The second class contains motors that incorporate a protonated Schiff base and are capable to achieve higher photoisomerization rates than overcrowded alkene-based motors. In the thesis, a new motor of this type is proposed that produces unidirectional rotary motion by means of two photochemical steps alone. Also, this motor lacks both a stereocenter and helical motifs, which are key features of almost all synthetic rotary motors developed to date. Men för att fullt ut dra nytta av dessa och andra motorers potential att fungera som effektiva kraftkällor i olika sammanhang, t.ex. för transport och målspecifik leverans av läkemedel i kroppen, är det emellertid av största vikt att ytterligare förbättra befintliga motorers prestanda, samt även att designa helt nya motorer som har mer fördelaktiga egenskaper. I avhandlingen presenteras forskning där flera möjligheter att möta dessa mål undersöks med olika beräkningsmetoder inom teoretisk kemi.Avhandlingens andra del handlar också om ljusabsorberande molekyler, s.k.kromoforer, men fokuserar på design och utvärdering av nya tillvägagångssätt för att beskriva exciterade energitillstånd hos sådana molekyler mer noggrant, utan att nödvändigtvis ta till kostsamma beräkningsmetoder. Speciellt undersöks möjligheten att på detta sätt beskriva organiska kromoforer av en typ som är relevant för solceller och lysdioder.vii

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Allosteric Regulation of the Rotational Speed in a Light-Driven Molecular Motor

Cited by 88 publications

References 65 publications

Quantum chemical design of rotary molecular motors

Quantum chemical design of rotary molecular motors

From coherent quasi-irreversible quantum dynamics towards the second law of thermodynamics: The model boron rotor B13+

Computational Design of Molecular Motors and Excited-State Studies of Organic Chromophores

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