# Fileset

[An inbuilt electronics paul gate.docx](https://mdr.nims.go.jp/filesets/02dd3c81-5ab8-4d6a-9a1e-6b38b8678eb2/download)

## Creator

Anup Singhania, Satadru Chatterjee, Sudeshna Kalita, Supriya Saha, Prerna Chettri, Firdaus Rahaman Gayen, Biswajit Saha, [Pathik Sahoo](https://orcid.org/0000-0002-5102-9482), [Anirban Bandyopadhyay](https://orcid.org/0000-0002-8823-4914), Subrata Ghosh

## Rights

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Applied Materials & Interfaces, copyright © 2023 American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acsami.3c01103[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[An Inbuilt Electronic Pawl Gates Orbital Information Processing and Controls the Rotation of a Double Ratchet Rotary Motor](https://mdr.nims.go.jp/datasets/822164a7-217c-4d74-9dae-1336ff50af6c)

## Fulltext

An Inbuilt Electronic Pawl Gates Orbital Information Processing and Controls the Rotation of a Double Ratchet Rotary MotorAnup Singhania,‡a,b Satadru Chatterjee,‡ a Sudeshna Kalita,a,b Supriya Saha,a,b Firdaus Rahaman Gayen,a,b Biswajit Saha,a,b Pathik Sahoo,c Prerna Chettri,a,b Anirban Bandyopadhyay,*c Subrata Ghosh,* a,ba CSIR-North East Institute of Science & Technology, Jorhat-785006, Assam, India. b Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India.c International Center for Materials and Nanoarchitectronics (MANA) and Research Center for Advanced Measurement and Characterization (RCAMC) National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki-3050047, Japan. KEYWORDS. Molecular motor, Brownian ratchet, Power stroke, Noise, Vibrational energy, Proton intercalationOne could build a nanofactory if all essential molecular components, motors, sensors and controllers operate independently and cooperatively while anchored to a single nanoplatform. Given the nanoplatform's wide range of applications, from medicine to space explorations, it is essential to design and synthesize programmable motors. For a decade, we have developed dendrimer-based nanoplatforms anchored to a double ratchet motor (DRM), which comprises a Brownian rotor (BR) and a power stroke (PS) rotor coupled to a −C≡C− stator—controls the energy flow by a proton-intercalation mechanism in the DRM resulting in different rotational thrusts and speeds (high/low/stop). Here, using suitable functional groups, we modulate the quantum transport of vibrational energy through coupled orbitals such that a conceptual linear vibrational energy flow chain (VEFC) forms. VEFC allows encoded quantum information to control the classical thermodynamics for harvesting thermal noise, -a prerequisite to orbital programming.     IntroductionMolecular nanofactory is a futuristic goal of nanotechnology, and molecular motors1,2 are the main executing components. It has the potential to revolutionize the research fields of energy harvesting, inventing ultra-fast quantum engines,3nanobots for bloodless surgery,4 and nanoarchitectonics.5-7 By definition, a molecular machine should do some physical work, following information written in its atomic orbitals; how this quantum information regulates classical thermodynamics is an open question, triggering the debate on thermodynamics of information content8 (Amano, S., Esposito, M., Kreidt, E. et al. Insights from an information thermodynamics analysis of a synthetic molecular motor. Nat. Chem. 14, 530–537 (2022). https://doi.org/10.1038/s41557-022-00899-z). So far, most invented molecular machines can generate mechanical thrust works at shallow temperatures (5K to 80K) due to their vibrational oscillations.9 As the temperature rises, the rotor machine rapidly passes through all steps to complete a periodic task. The stator of a rotor controls the direction,10 and the functional group in a rotor completes a 360ο rotation,11 the wheels of a nano car complete one rotation,12 the period for a quantized rotation is homogeneously distributed among all steps. A homogeneous rotational speed of a motor cannot deliver complex tasks. However, a proper mechanism to design a stepper motor that brakes at desired angles to deliver a programmed thrust is still in progress.13 Attempts were made to induce one plodding step (0.005 seconds) using the thermally induced helix-inversion.14,15 It is still to be found how does a choice of the functional group could deliver inhomogeneous rotations in a molecular motor. A stepper motor should have at least four steps;16 during a 360ο rotation, the rotating part would slow down at particular angles and then speed up.17,18 Efforts were plenty, from interface modification,19 chemical fueling,20 and atomically precise external control;21 the continuous rotation appears as quantum control by molecular orbital. Therefore, we need a quantum design strategy for regulating step-by-step angular rotation at the molecular scale. Feynman proposed the nanomachine and suggested implementing two ratchets or control livers in one system to avoid thermodynamical Maxwell's demon.22-24 Most machines invented thus far have one ratchet in the molecule, and the other ratchet's task was performed by creating an energy gradient externally. That is why in all machines, we find an external influence.25-26Recently, we resolved this issue by implementing a PS rotor in a double ratchet motor.27 We fused two classic biological motor concepts, PS and BR, in a single motor.28-29 Here, the coupled orbital network connecting the two planes of the motor is used  to conceptualize an atomic chain of vibration, we named it VEFC engineering.30,31 Coupled  orbitals passing through the junction of two planes act as a critical quantum energy transport channel. In this channel, through molecular orbitals, the absorbed noise extracted energy packet transmits connecting the molecule's functional parts. Thus, the chain of atoms may act as programmable machinery if we could change the distribution of energy on the atomic sites in the desired way by choosing the functional groups. Here we have added functional group OH through an auxiliary molecule (AM) so that the activity of the energy flowing chain is programmed to deliver a step-wise thrust within a 360o rotation (Scheme 1). We could pause/play the rotation of the BR module of DRM by controlling VEFC to switch the motion of the PS module. Herein we describe AM's fabrication method as an internal control of DRM. We also report AM's intramolecular proton intercalation (IMPI) mechanism to control VEFC. If PS couples with AM, the N-atom of the resulting Schiff-base can participate in the proton intercalation process32 via a strong hydrogen bonding that may even disrupt the normal state of orbital density fluctuations that fuel the BR motion.Since the invention of ultra-high vacuum scanning tunneling microscopy (UHV-STM),39 discoveries have proved that the electron density distribution in the molecular orbitals is a quantum mechanical phenomenon.40 This distribution involves a dynamic motion of the electron clouds through the bonding, antibonding, and non-bonding orbitals around the atoms aligned along the bonds in the molecule. We need a better scientific understanding of all the influencing factors of a single molecule's orbital density distributions. Herein, we have described that a partial proton translocation towards either end of the hydrogen-bonded atoms is essential in influencing the VEFC. BR in DRM has unrestricted rotation at ambient temperature; if PS forms hydrogen bonding, the BR motion ceases. If we remove H-bonding, the BR motion can restart to the next point. With the increasing demand for single-molecule electronics, such a study is highly relevant for energy harvesting and conservation.41-43At a shallow temperature, we expect a motion restriction of BR and observe two or more different rotamer states (e.g., near planar, out of the plane, near perpendicular, etc.) of the DRM. Using VT-NMR spectroscopy 33-34 (see Supporting Information, Figure S-1a), we have shown that the thermal noise-operated motor changes relative distances of aromatic planes, which is attributed to a triangular shape inversion (see Supporting Information, Figure S-1b). Therefore, we can program a quantum orbital-energy transmission route in a rotor to slow down the quantized rotation.35-38Power harvesting molecular motors should be designed to be autonomous powered systems. Instead of depending on external input energy, it is expected that external factors should be applied to control/cease their motion. These factors would also minimize input power consumption and produce maximum output power. In most cases, restricted rotation in a molecular rotor is controlled by bond breaking-making, interaction due to steric crowding, hydrogen bonding interaction, buttressing effect, etc.48-52 Recently, we have reported that a molecular rotor work under ambient conditions; thermal kT would be sufficient to induce mechanical motion in the molecule. It is implemented respectively in a PCM and a PCMS nano-platforms to produce some giant nano-structures and resonance energy-inducing drug materials by controlling their dynamics through different electromagnetic energy pumping.55-56 The molecular rotor structure is self-powered and can harvest energy from the ambient temperature.27 To our knowledge, this is the first report of an embedded VEFC, a speed controller of a molecular motor.Results and discussionRestricted phenyl ring rotation around a single bond in a biphenyl molecule results in atropisomerism. The factors that influence such restricted rotation are electronic and steric.57 Double bonds and triple bonds do not rotate; however, Ben Feringa's group has discovered molecular motors of different generations where relative rotation of plans around the double bond takes place by photoexcitation mechanism. A single bond next to a C≡C bond can rotate, and J M. Tour's group uses this mechanism to produce nanocar.58 So, electronic factors will likely cause the molecule's restricted rotation at the two terminals of a C≡C bond. Our report shows that electronic factors can impact the single bond rotation attached to a triple bond (Figure 1a). Earlier, we reported the method of unison of many such motors via radio wave triggering.27 The challenge is controlling the rotational speed of the motor. Therefore, we must investigate if a such rotational restriction is embedded with the molecular orbitals and how the VEFC influences such controlled rotation. The simple way to describe VEFC is a transient electron density distribution change with a change in the atomic environment in the molecule.63 Here, we have explored the mechanism of molecular rotor motion, and its control evolves from the molecular orbital (MO) levels. This would be the first report of pawl-like use of AM and BR's motion control by the dynamic VEFC. This experimental fact reveals that instead of breaking any chemical bond, a molecular electron density distribution (Figure 1b) could control a molecular rotor having angular velocity. A rigorous 1H and 13C NMR analyses of DRM show that all protons and carbon peaks in the spectrum have a regular appearance at room temperature. We speculate the reason may be the faster rotational speed (THz, ps order) (see the Supporting Information, Video 1) of BR vs. PS under the NMR scanner (MHz, µs order) to detect the asymmetric protons.64-66 of rotamers. However, a variable temperature 1H-NMR spectra analysis of the DRM starting from 213K (-60 oC) to 313K (40 οC) shows an unusual peak shifting of some of the protons in both the BR and PS modules (see the Supporting Information, Figure S-8a & Table 2). We identified that these particular protons belong to BR and PS at two terminals of the rotor molecule. This result can explain VEFC as an active electronic orbital communication channel, which can play a pivotal role in controlling the staggered rotor motion of the BR and PS. At 213K, the protons associated with the −OCH3 group on the BR appeared as two singlets at δ (in ppm) 4.00 (singlet) and δ 3.73 (singlet). The intensity of the former peak is less than the latter. At 313K, the same set of protons shifts from δ (in ppm) 4.00 to 3.97 (singlet) and from 3.73 to 2.72 (singlet); the peak intensity of the former one is now consistently more prominent than the last peak. Therefore, it is evident that at various temperatures from lower to higher, different rotamers at different quantized states reach particular conformations where orbital density on methyl group of -OCH3 has intensified to shield the protons. Since the planar conformation is less affected by such a shielding effect, non-planar conformation is observed to have a significant shielding effect. Here we observe only those 1H-NMR peaks for populated rotamers present in the solution at a detectable concentration under the instrument limit.Nevertheless, we see aromatic protons of the BR appear only once, though we expected them to be at least double. Also, sometimes we observe very low-intensity singlet peaks for the up-field protons of −OCH3 at some temperatures, while the other peaks remain unchanged. We speculate that over the rotation, as we previously observed under UHV-STM images and reported elsewhere,27 the molecule reached some bent conformations (Figure 1c). In these temporary conformations, the information of methyl protons was temporarily lost due to the shielding environment of π-electron clouds of −C≡C− bond. On the other side, the protons of the amine group shifted from δ (in ppm) 6.40 (at 213K) to 5.56 (at 313K), which may be attributed to some dynamic electron shielding on the N atom due to out-of-plane wagging vibrations at a higher temperature (Figure 1d). A variation of the measurable peak shifts and varying intensities of particular aromatic protons are observed at different temperatures (see Supporting Information, Figure S-8d). This significant phenomenon is attributed to the temperature-dependent dynamic conformational change and the corresponding ring current oscillations.In our DRM structure (Scheme 1), if both the BR and PS planes are coplanar, the HOMO has a significant orbital contribution from the upper aromatic BR plane. Still, as soon as the BR plane is rotated away from the coplanar conformation, the orbital density is shifted towards the aromatic naphthyl group of the PS (Figure 1e). We attribute this to quantized rotations around the axis of rotation. However, Gaussian calculation shows that the rotational barrier among the coplanar and non-planar structures is relatively narrow (see Supporting Information, Figure S-9) and equivalent to only three kT (see Supporting Information, Table 1). Later by introducing AM, we could observe that coupling reaction results in both coplanar and non-planar products (Scheme 1), which appeared in the thin layer chromatography as two overlapped spots. One of the spots has bright luminescence, while the other appears dull when both are excited with (λmax) 365 nm radiation.Further analysis by NMR spectroscopy shows that the two compounds are distinctly present in the mixture in an almost equivalent ratio. From Figure 1, we can also predict that the −NH2 and the −OCH3 groups in the molecule are crucial factors influencing this rotational feature of the DRM. So, we aimed to temporarily break or tune the intercommunication between these two groups by adding some items. Hence, we took a theoretical approach before experimentally investigating the molecular rotation guiding factors. After studying the LUMO, we observed that the orbital density is shifted from the phenyl ring of BR to the naphthyl ring of PS, where the H-bonding between the corresponding protons of a phenolic ortho- hydroxyl group is attached to the AM, and N atom of the Schiff base favours the IMPI. On the other structure [LR1], where the aromatic planes are non-planar, the HOMO of the BR has more orbital density, and the LUMO also has almost comparable orbital density. So, we found that if we use a suitable ortho-hydroxy aromatic aldehyde to synthesize the corresponding Schiff base derivative of the DRM, as shown in Scheme 1, then characteristic molecular dynamics are observed. It also shows that the rotational hindrance is observed even at room temperature, depending on the availability and proximity of the phenolic H atom to the N atom that is a part of the Schiff base.Our earlier report shows that when the BR part absorbs energy (kT) at ambient temperature and gets activated. A VEFC is lined up from the BR part to the PS part through the triple bond stator. Thus, we observed that the O atom of the −OCH3 group and the N atom of the −NH2 group play an active role in the asymmetric variation of the dynamic orbital behaviour. We demonstrate here how these two heteroatoms participate in molecular dynamics. We aimed to investigate the probable controlling parameters that can effectively arrest the rotational motion by targeting the VEFC. We have designed a few active structures to initiate the IMPI process in DRM. The general synthetic scheme started by preparing 3 (Scheme 1). We performed the reaction in different solvent conditions (e.g., CH3CN, THF, and DMF) under an inert gas atmosphere to get compound 5 [LR]. Depending on the AM, we get two products, 7 [LR1] & 9 [LR2], as a sticky liquid in 70% & 75% yield, respectively (Scheme 2).31 In this study, we envisioned regulating the rotational dynamics of the BR by electron flow control throughout the system by AM from another end. We kept two things in mind while choosing a good AM; firstly, the molecule should be electron deficient so that the electronic flow moves towards it, and secondly, the addition of some extra flavor by incorporating a good chromophore or fluorophore (with high stoke shift) or both for proper visualization. After doing a literature survey, we concluded that the only thing which can tactfully solve our purpose is ESIPT. Henceforth, we incorporated the same judiciously synthesizing the above two molecules, LR1 and LR2 (Figure 2a,b). Both the compounds were chromophores (LR1 is yellow and LR2 is orange) due to the −C=N bond, which shows low energy (n →π*) electronic transitions. Simultaneously, they were found to have fluorescence (due to proton translocation via ESIPT) with a high Stokes shift (> 100 nm) (see Supporting Information, Figure S-10). We systematically studied the pure compounds and how the IMPI controls the rotor's behavior (see Supporting Information, Video 2). While characterizing compound LR1, we observed several other protons in the 1H-NMR spectra. On finding the source of these additional protons, we found that the noticeable change was in the −OCH3 region of the molecule, where two distinct methyl peaks with equal integrations showed up (Figure 2c). Not only that, but we also found some additional peaks in the aromatic region. It is noteworthy that we have performed the reaction in THF, a comparatively less viscous solvent (0.46×10-3 Pa s); thus, maybe until it reaches the state of rotational hindrance, the BR part gets time to reach different orientations in the NMR time scale. To confirm, we have performed the reaction in DMF, which is a more viscous solvent (0.80×10-3 Pa s). Surprisingly, we observed no ambiguities in 1H-NMR, which confirmed that more viscous solvent DMF did not allow the BR part of the molecule to rotate freely under similar reaction conditions. To go deeper into this study, we created one analogous molecule, LR2, in THF medium, with an AM containing a naphthyl ring. However, this molecule did not attest to similar observations (Figure 2d), and there is no significant change in the shifting of protons of the −OCH3 group in the BR. However, based on the arbitration by the H-bonding proton present in the system, we could explain the additional changes in the low-field protons region. Viscous solvent DMF did not allow the BR part of the molecule to rotate freely under similar reaction conditions. We have also performed the reaction in different solvents as a controlled study but found the same results. Compound 3, corresponding to LR2, shows the same kind of NMR pattern, which was missing in the compound of LR1. Hence, it is evident that some ESIPT-type mechanisms may play a crucial role here.      According to the result, we hypothesized that in the case of LR1, IMPI is weak and strong ESIPT might be helping the molecule to get different particular orientations. Thus, two possible orientations of the BR part are possible, leading to this structural ambiguity. When phenolic hydrogen of AM part can intercalate between the O atom of phenol and the N atom in the PS part, hydrogen bonding occurs. Then rotational motion is ceased as observed in structure LR1′ (minor, fluorescent) and structure LR1″(major, non-fluorescent). Thus, when the auxiliary molecular part, salicylaldehyde Schiff base, is attached to the DRM, the resulting DRM shows a unique NMR spectrum (see Supporting Information, Figure S-11a-c) in which the protons from the phenyl group of the BR module appeared double the number than expected (Figure 2c). However, keeping the sample at ambient temperature showed the conversion of the less stable LR1″ rotamer to the more stable fluorescent rotamer LR1′ (Figure 2a). It is noteworthy because a weak IMPI process allows a flexible locked rotamer to convert to a stable H-bonded rotamer; one of the two singlets of non-degenerate methoxy protons disappears. Cyclic voltammetry study of LR1 resulted in a crossover between forward and backward scan (Figure 2f), which supports an ECE mechanism81 in the process in LR1, and we have discussed the keto-enol isomerization in online Supporting Information (Figure S-10).However, in LR2, the strong IMPI replaces the ESIPT process.67-69 Hence, pre-orientation was already there in the molecule (as seen in Figure 2). Not only that, but the total electron flow was already towards the BR part of the molecule as the N atom of the −C=N became more electron-deficient during IMPI. Both these factors helped LR2 stabilize in a particular arrangement, disabling the BR's rotating property. On the other hand, compound LR2, due to higher stabilization from the IMPI process of the H atom of naphthol, can bind with nitrogen atoms tightly (see Supporting Information, Figure S-12). 1H-NMR indicated the dynamic translocation of the H atom on the phenolic oxygen between the N and O atoms (Figure 2d). Therefore, the orbital density fluctuation process is ceased, so rotamer LR2″ is disfavored, and only structure LR2′ (fluorescent) is observed. Two SI video files70 of theoretical simulations closely corroborate these arguments.ConclusionsIn summary, molecular programmability offered by VEFC embedded inside the linear chain of functional groups in a molecule could affect quantum transmissions (refer nano letters here). Here we have shown IMPI and ESIPT control on the VEFC, it is more profound quantum information analog than that claimed earlier.8 When a lone pair of electrons on the amine nitrogen is available, orbital density fluctuation controls the BR and PS parts to interact and continue the rotational motion. Electron-donating or withdrawing functional groups can modulate VEFC. Thus, VEFC may be compared with a dynamic programming tool for molecular machines that could bring wide ranges of mobility, transformability, and self-assembling abilities into the motor network. Most importantly, we have shown earlier that it is possible to control VEFC remotely, which means one could wirelessly switch on/off the quantized mechanical thrust produced by a motor, enabling global control on the atomic scale of physical tasks molecularly programmed in the resonance chain. VEFC-control would deliver chemists a tool for stepper motor application in nanorobotics, ligand modification for the catalyst activity and increased catalysis cycles, and ESIPT-triggered device design.ASSOCIATED CONTENTSupporting Information. The art of controlling the rotor speed of a molecular motor is presented in the current article with all supporting data and details analysis. "This material is available free of charge via the Internet at http://pubs.acs.org."Material and method, Full Experimental details, 1H, 13C, and VT-NMR, PL data, Computational data, and additional data. Supporting VideosAUTHOR INFORMATIONCorresponding Author*Anirban Bandyopadhyay- International Center for Materials and Nanoarchitectronics (MANA) and Research Center for Advanced Measurement and Characterization (RCAMC) National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki-3050047, Japan. E-mail: anirban.bandyo@gmail.com*Subrata Ghosh-CSIR-North East Institute of Science & Technology, Jorhat-785006, Assam, India. Academy of Scientific and Innovative Research (AcSIR), Ghaziabad - 201002, India. E-mail: ocsgin@gmail.comAuthor Contributions‡  AS and SC contributed equally to this work.NotesThere are no conflicts to declare.ACKNOWLEDGMENTThe authors acknowledge SERB Government of India for Grant ECR/2016/001534 (2017-2020), CSIR India for Grant HCP-021 (2019-2020), and acknowledge the Asian office of Aerospace R&D (AOARD), a part of the United States Air Force (USAF) for Grant FA2386-16-1-0003 (2016−2019). The authors thank CSIR-NEIST and NIMS Sengen-site for providing the necessary utilities and support.ABBREVIATIONSDRM, Double ratchet motor; PS, Power stroke, BR, Brownian rotor; IMPI, Intramolecular proton intercalation, AM, Auxiliary molecule; ESIPT, Excited-state intramolecular proton transfer; VEFC, Vibrational energy flow chain; UHV-STM, Ultra-high vacuum scanning tunneling microscope; TLC, Thin layer chromatography.REFERENCES1. Lancia, F., Ryabchun, A. Katsonis, N. Life-like motion driven by artificial molecular machines. Nat. Rev. Chem. 2019, 3, 536–551.2. Lino, R.; Kinbara, K.; Bryant, Z. Introduction: molecular motors. Chem. Rev.2020, 120(1), 1-4.3. Campo, A. D.; Goold, J.; Paternostro, M. More bang for your buck: Super-adiabatic quantum engines. Sci. Rep.2014, 4, 6208, 1-5.4. Mali, S. Nanotechnology for surgeons. Indian J. Surg. 2013, 75, 485-92.5. Ariga, K. Mechano‐nanoarchitectonics: design and function. Small Methods 2022, 6, 2101577.6. Ghosh, S.; Chatterjee, S.; Roy, A.; Ray, K.; Snehasikta, S.; Fujita, D.; Bandyopadhyay, A. Resonant oscillation language of a futuristic nano-machine-module: eliminating cancer cells &alzheimer aβ plaques. Curr. Top. Med. Chem. 2015, 15, 534-541.7.  López, V. G-.; Chen, F.; Nilewski, L. G.; Duret, G.; Aliyan, A.; Kolomeisky, A. B.; Robinson, J. T.; Wang, G.; Pal, R.; Tour, J. M.  Molecular machines open cell membranes. Nature 2017, 548, 567-572. 8. Guentner, M.; Schildhauer, M.; Thumser, S.;Mayer, P. J.; Dube,H. Sunlight-powered kHz rotation of a hemithioindigo-based molecular motor. Nat. Commun. 2015, 6, 8406.9. Chérioux, F.; Galangau, O.; Palmino, F.; Rapenne, G. Controlled directional motions of molecular vehicles, rotors, and motors: from metallic to silicon surfaces, a strategy to operate at higher temperatures. Chem. Phys. Chem. 2016, 17, 1742-1751.10. Kudernac, T.; Ruangsupapichat, N.; Parschau, M.; Maciá, B.; Katsonis, N.; Harutyunyan, S. R.; Ernst, K. H.; Feringa, B. L. Electrically driven direc-tional motion of a four-wheeled molecule on a metal surface. Nature 2011, 479, 208–211.11. Kudernac, T.; Ruangsupapichat, N.; Parschau, M.; Maciá, B.;                                  Katsonis, N.; Harutyunyan, S. R.; Ernst, K. H.; Feringa, B. L. Electrical-ly driven directional motion of a four-wheeled molecule on a metal surface. Nature 2011, 479, 208–211.12. Simpson, G. J.; García-López, V.; Petermeier, P.; Grill, L.; Tour, J. M. How to build and race a fast nanocar. Nat. Nanotech. 2017, 12, 604-606.13. Asato, R.; Martin, C. J.; Abid, S.; Gisbert, Y.; Asanoma, F.; Nakashima, T.; Kammerer, C.; Kawai, T.; Rapenne, G. Molecular rotor functionalized with a photoresponsive brake. Inorg. Chem. 2021, 60, 3492-3501.14. Vicario, J.; Walko, M.; Meetsma, A.; Feringa, B. L. Fine-tuning of the rotary motion by structural modification in light-driven unidirectional molecular motors. J. Am. Chem. Soc. 2006, 128, 5127-5135.15. Chen, Z. J.; Lu, H.F.; Chiu, C. W.; Hou, F. M.; Matsunaga, Y.; Chao, I.; Yang, J. S. A molecular rotor that probes the helical inversion of stiff-stilbene. Org. Lett. 2020, 22, 9158-9162.16. Vicario, J.; Meetsma, A.; Feringa, B.L. Controlling the speed of rotation in molecular motors. Dramatic acceleration of the rotary motion by structural modification. Chem. Commun. 2005, 47, 5910-5912.17. Wu, Y.; Wang, G.; Li, Q.; Xiang, J.; Jiang, H.; Wang, Y. A multistage rotational speed changing molecular rotor regulated by pH and metal cations. Nat. Commun. 2018, 9, 1953, 1-10.18. Lin, Y.; Dahl, B.J.; Branchaud, B.P. Net directed 180 aryl–aryl bond rotation in a prototypical achiral biaryl lactone synthetic molecular motor. Tetrahedron lett. 2005, 46, 8359-8362.19. Carroll, G.T.; London, G.; Landaluce, T.F.; Rudolf, P.; Feringa, B.L. Adhesion of photon-driven molecular motors to surfaces via 1, 3-dipolar cycloadditions: effect of interfacial interactions on molecular motion. ACS Nano 2011, 5, 622–630.20. Wilson, M.R.; Solà, J.; Carlone, A.; Goldup, S.M.; Lebrasseur, N.; Leigh, D. A. An autonomous chemically fuelled small-molecule motor. Nature 2016, 534, 235-40.21. Stolz, S.; Gröning, O.; Prinz, J.; Brune, H.; Widmer, R. Molecular motor crossing the frontier of classical to quantum tunneling motion. Proc. Nat. Acad. Sci. 2020, 117, 14838-14842.22. Feynman, R. P.; Leighton, R. B.; Sands, M. The Feynman Lectures on Physics; Addison-Wesley: Reading, MA 1963, 1, Chapter 46.23. Feynman, R. P.; Vernon, F. L. The theory of a general quantum system interacting with a linear dissipative system. Ann. Phys. 1963, 24, 118−173.24. Cargill Gilston Knott "Quote from undated letter from Maxwell to Tait". Life and Scientific Work of Peter Guthrie Tait. Cambridge University Press. 1911, 213-215.25. Kay, E.R.; Leigh, D.A. Rise of the molecular machines. Angew. Chem. Int. Ed. 2015, 54, 2–11.26. Tu, Y.; Peng, F.; Sui, X.; Men, Y.; White, P.B.; van Hest, J.; Wilson, D. A. Self-propelled supramolecular nanomotors with temperature-responsive speed regulation. Nat. Chem. 2017, 9, 480-486.27. Singhania, A.; Ghosh, I.; Sahoo, P.; Fujita, D.; Ghosh, S.; Bandyopadhyay, A. Radio Waveguide–Double Ratchet Rotors Work in Unison on a Sur-face to Convert Heat into Power. Nano Lett. 2020, 20, 6891-6898.28. Hwang, W.; Karplus, M. Structural basis for power stroke vs. Brownian ratchet mechanisms of motor proteins. PNAS 2019, 116, 19777–19785.29. García-López, V., Liu, D.; Tour, J. M. Light-activated organic molecular motors and their applications. Chem. Rev. 2019, 120, 79-124.30. Borrelli, R.; Gelin, M. F. Quantum dynamics of vibrational energy flow in oscillator chains driven by anharmonic interactions. New J. Phys. 2020, 22, 123002.31. Oxtoby, D. W. Vibrational relaxation in liquids. Annual Review of Physical Chemistry 1981, 32, 77-101.32. Zhao, Q.; Liu, L.; Yin, J.; Zheng, J.; Zhang, D.; Chen, J.; Archer, L. A. Proton intercalation/de-intercalation dynamics in vanadium oxides for aque-ousaluminum electrochemical cells. Angew. Chem. Int. Ed. 2020, 59, 3048–3052.33. Biswas, P. K.; Goswami, A.; Saha, S.; Schmittel, M. Dynamics of Hydrogen Bonding in Three-Component Nanorotors. Chem. Eur. J. 2020, 26, 14095-14099.34. Alam, P.; Leung, N. L. C.; Cheng, Y.; Zhang, H.; Liu, J.; Wu, W.; Kwok, R. T. K.; Lam, J. W. Y.; Sung, H. H. Y.; Williams, I. D.; Tang, B. Z. Spontaneous and fast molecular motion at room temperature in the solid state. Angew. Chem. Int. Ed. 2019, 58, 4536-4340.35. Dijk, L. V.; Tilby, M. J.; Szpera, R.; Smith, O.A.; Bunce, H. A. P. Molecular machines for catalysis. Nat. Rev. Chem. 2018, 2, 0117.36. Sedgwick, A. C.; Wu, L. Han, H. –H.; Bull, S. D.; He, X. –P.; James, T. D.; Sessler, J. L.; Tang, B. Z.; Tian, H.; Yoo, J. Excited-state intramolecular pro-ton-transfer (ESIPT) based fluorescence sensors and imaging agents. Chem. Soc. Rev. 2018, 47, 8842-8880.37. Kumsampaoa, J.; Chaiwai, C.; Sukpattanacharoen, C.; Chawanpunyawat, T.; Nalaoh, P.; Chasing, P.; Kungwan, N.; Sudyoadsuka, T.; Promarak, V. Self-absorption-free excited-state intramolecular proton transfer (ESIPT) emitters for high brightness and luminous efficiency organic fluores-cent electroluminescent devices. Mater. Chem. Front. 2021, 5, 6212-6225.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             38. Bo, G. D.; Gall, M. A. Y.; Kuschel, S.; Winter, J. D.; Gerbaux, P.; Leigh, D. A. An artificial molecular machine that builds an asymmetric catalyst. Nat. Nanotech. 2018, 13, 381-385.39. Binnig, G.; Rohrer, H.; Gerber, C.; Weibel, E. Surface studies by scanning tunneling microscopy. Phys. Rev. Lett. 1982, 49, 57–61.40. Jelínek, P. High resolution SPM imaging of organic molecules with functionalized tips. J. Phys.: Condens. Matter 2017, 29, 343002.41. Frisbie, C. D.; Designing a robust single-molecule switch. Science 2016, 352, 1394-1395.42. Xin, N.; Guan, J.; Zhou, C. Concepts in the design and engineering of single-molecule electronic devices. Nat. Rev. Phys. 2019, 1, 211-230.43. Li, Z.; Gao, C. Y.; Su, D.; Jia, C.; Guo, X. Principles of Molecular Machines at the Single-Molecule Scale. ACS Mater. Lett. 2021, 3, 1484-1502.44. Dattler, D.; Fuks, G.; Heiser, J.; Moulin, E.; Perrot, A.; Yao, X.; Giuseppone, N. Design of collective motions from synthetic molecular switches, rotors, and motors. Chem. Rev. 2020, 120, 310−433.45. Astumian, R. D. Optical vs. chemical driving for molecular machines. Faraday Discuss. 2016, 195, 583-597.46. Pezzato, C., Cheng, C.; Stoddart, J. F.; Astumian, R. D. Mastering the non-equilibrium assembly and operation of molecular machines. Chem. Soc. Rev. 2017, 46, 5491-5507.47. Heard, A. W.; Goldup, S. M. Simplicity in the Design, Operation, and Applications of Mechanically Interlocked Molecular Machines. ACS Central Science 2020, 6, 117-128. 48. Comotti, A.; Bracco, S.; Valsesia, P.; Beretta, M.; Sozzani, P. Fast molecular rotor dynamics modulated by guest inclusion in a highly organized nanoporousorganosilica. Angew. Chem. Int. Ed. 2010, 49, 1760-1764.49. Faulkner, A.; Leeuwen, T. V.; Feringa, B. L.; Wezenberg, S. J. Allosteric regulation of the rotational speed in a light-driven molecular motor. J. Am. Chem. Soc. 2016, 138, 13597-13603.50. Rushton, G. T.; Vik, E. C.; Burns, W. G.; Rasberry, R. D.; Shimizu, K. D. Guest control of a hydrogen bond-catalysed molecular rotor. Chem. Com-mun. 2017, 53, 12469-12472.51. Alfonso, I.; Burguete, M.I.; Luis, S. V. A hydrogen-bonding-modulated molecular rotor:  environmental effect in the conformational stability of peptidomimetic macrocyclic cyclophanes. J. Org. Chem. 2006, 71, 2242–2250.52. Pijper, D.; Delden, R. A. V.; Meetsma, A.; Feringa, B. L. Acceleration of a nanomotor:  electronic control of the rotary speed of a light-driven mo-lecular rotor. J. Am. Chem. Soc. 2005, 127, 17612-17613.53. Badjic, J. D.; Balzani, V.; Credi, A.; Silvi, S.; Stoddart, J. F. A. Molecular elevator. Science 2004, 303, 1845-1849.54. Cakmak, S. E.; Fielden, S. D. P.; Karaca, U.; Leigh, D. A.; McTernan, C. T.; Tetlow, D. J.; Wilson, M. R. Rotary and linear molecular motors driven by pulses of a chemical fuel. Science 2017, 358, 340–343.55. Ghosh, S.; Dutta, M.; Sahu, S.; Fujita, D.; Bandyopadhyay, A. nano molecular-platform: a protocol to write energy transmission program inside a molecule for bio-inspired supramolecular engineering. Adv. Funct. Mater. 2014, 24, 1364-1371.56. Ghosh, S.; Roy, A.; Singhania, A.; Chatterjee, S.; Swarnakar, S.; Fujita, D.; Bandyopadhyay, A. In-vivo & in-vitro toxicity test of molecularly engi-neered PCMS: A potential drug for wireless remote controlled treatment. Toxicol. Rep. 2018, 5, 1044–1052.57. Costil, R.; Sterling, A. J.; Duarte, F.; Clayden, J. Atropisomerism in diarylamines: structural requirements and mechanisms of conformational interconversion. Angew. Chem. Int. Ed. 2020, 59, 18670– 18678.58. Guirgisa, G. A.; Bellb, S.; Deebc, H.; Zhengc, C.; Durig, J. R. Infrared and Raman spectra, ab initio calculations, barriers to internal rotation, and vibrational assignment of 4-fluoro-2-pentyne. J. Mol. Struc. 2004, 706, 141–152.59. Kassem, S.; Lee, A.; Leigh, D.; Markevicius, A.; Solà, J. Pick-up, transport and release of a molecular cargo using a small-molecule robotic arm. Nat. Chem. 2016, 8, 138–143.60. Lard, M.; Siethoff, L.; Kumar, S.; Persson, M.; Kronnie, G.; Linke, H.; Månsson, A. Ultrafast molecular motor driven nanoseparation and biosens-ing. Biosens. Bioelectron. 2013, 48, 145-152. 61. Franken, L. E.; Wei, Y.; Chen, J.; Boekema, E. J.; Zhao, D.; Stuart, M. C. A.; Feringa, B. L. J. Am. Chem. Soc. 2018, 140, 7860-7868.62. Dong, J.; Wee, V.; Peh, S. B.; Zhao, D. Molecular-rotor-driven advanced porous materials. Angew. Chem. Int. Ed. 2021, 60, 16279-16292.63. Jones, G. A.; Bradshaw, D. S. Resonance energy transfer: from fundamental theory to recent applications. Front. Phys. 2019, 7, 100.64. Bryant, R. G.The NMR time scale. J. Chem. Edu. 1983, 60, 933-935.65. Xu, Z.; Liu, C.; Zhao, S.; Chen, S.; Zhao, Y. Molecular Sensors for NMR-Based Detection. Chem. Rev.2019, 119, 195−230.66. Nicholson, R. S.; Shain, I. Theory of stationary electrode polarography for a chemical reaction coupled between two charge transfers. Anal. Chem. 1965, 37, 190–195.67. Alarcos, N.; Gutierrez, M.; Liras, M.; Sánchez, F.; Douhal, A. An abnormally slow proton transfer reaction in a simple HBO derivative due to ultrafast intramolecular-charge transfer events. Phys. Chem. Chem. Phys. 2015, 17, 16257-16269.68. Perveaux, A.; Lorphelin, M.; Lasorne, B.; Lauvergnat, D. Fast and slow excited-state intramolecular proton transfer in 3-hydroxychromone: a two-state story? Phys. Chem. Chem. Phys. 2017, 19, 6579-6593.69. Joshi, H. C.; Antonov, L. Excited-state intramolecular proton transfer: a short introductory review. Molecules 2021, 26, 1475.70. Shenogin, S.; Ozisik, R. XenoView v.3.4 2007 Available online: http://www.vemmer.org/xenoview/xenoview.html  Scheme 1. DRM (I) results in two Schiff base varieties (II) and (III) when reacted with salicylaldehyde and naphthaldehyde (above). General reaction scheme of synthesis of Schiff bases of DRM (below).Scheme 2. Reagents: Pd(PPh3)3Cl2/CuI, and Et3N as a base. Two rotamers, LR1ʹ and LR1ʺ, have resulted in from 6 via a proposed intermediate structure 7 (i.e., LR1) (above). Single rotamer LR2ʹ is formed from 8 via a proposed intermediate 9 (i.e., LR2). Figure 1. (a) A drawing of DRM in motion, where BR can harvest thermal/electromagnetic noise (kT) and rotate freely in an angular path around 360o; R1, R2, R3, etc., are BR planes in space at various rotational states. PS has a flipper motion and produces a thrust under a downhill energy gradient. (b) Images of a DRM under a scanning tunneling microscope; the first and second differential of the orbital density distributions resulted in less noisy images featuring the orbital embedded VEFC. The second differential image shows density distribution concentrated on two hetero-atoms. (c) Orbital density images (scale bar = 0.5 nm) of different rotamer states. (d) The proximity of CH3 protons to the C≡C bond. Temperature-dependent proton NMR spectra of DRM, NH2, and CH3 protons follow an up-field shift with rising temperature. (e) DFT study of rotamers and corresponding HOMO densities.  Figure 2. (a) Chemical structure of LR1 (DRM derivative) with favoured interconversion and different rotamers. (b) Chemical structure of LR2 (DRM derivative) with disfavoured rotamers. (c) 1H-NMR spectrum (in CD3CN) of LR1; the spectrum of LR1′ (above, blue), a rotamer is formed in reaction condition using DMF (high viscous solvent); proton Ha is intercalated between N and O atoms, and a strong IMPI is displayed by a dynamic change of proximity between N and Ha, which is attributed to the shifting of Ha peak to Ha′ and the corresponding shifting of Hb peak to Hb′. 1H-NMR spectrum (in CD3CN) of rotamers LR1′ and LR1″ (below, maroon), which are formed in the reaction using THF (low viscous solvent), so IMPI is weak and allows the ESIPT process to operate. (d) A 1H-NMR spectrum of LR2' where Hp is strongly intercalated between N and O atoms. A dynamic change of proximity between N and Hp is attributed to the shifting of Hp peak to Hp′, which is supported by the corresponding shifting of Hq peak to Hq′. (e) The resulting emission data of DRM obtained from CEES spectroscopy is plotted: (1) Scattered plot of emission vs. solvent viscosity (10-3 Pa s). MeOH = 0.54, Ethanol = 1.08, EtOAc = 0.43, DMF = 0.80, CHCl3 = 0.54. With the increase in viscosity of the solvent, emission shift to lower energy region where chloroform is an exception may be because of a counter effect of a high density of chloroform. (2) Scattered emission plot vs solvent density (g/mL). MeOH = 0.791, Ethanol = 0.789, EtOAc = 0.894, DMF = 0.948, CHCl3 = 1.498. Except for ethanol, we can see a natural emission shift from higher to lower energy with increasing solvent density. (f) Cyclic voltammogram of LR1 is observed with a crossover between forwarding and backward scan. It clearly shows that an ECE mechanism (see supporting information, Figure S-23) is associated with the rotation of LR1.Insert Table of Contents artwork here5 | Pageimage3.jpegimage4.jpegimage5.jpegimage1.wmfOHBrNH2OHNBrOHNO(a)(b)123LRR= H, Fused phenylO4RCHORR5NOHNOHOOONH2IIIIIIBR PartPS PartAM PartPS PartBR PartBR PartPS PartAM PartDRMIMPIIMPIimage2.emfBrNOHBrNONH3CO7 [LR1]O[LR1'] Planar rotamer[LR1"] Non-planar rotamerNH3COOHNH3COOH66'BrNOHBrNOHH3CO9 [LR2][LR2'] Planar rotamer[LR2"] Non-planar rotamerNH3COOHNH3COOH8'8NOHHH[LR1'] Planar rotamerNH3COOHESIPTIMPIDMF solv.THF solv.WeakStrongWeakStrongConversion