Artificial Molecular Rotors

Kottas, Gregg S.; Clarke, Laura; Horinek, Dominik; Michl, Josef

doi:10.1021/cr0300993

Cited by 1,139 publications

(860 citation statements)

References 888 publications

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“…Treatment of the readily available hexabromoosmate(IV) salt (NH 4 ) 2 OsBr 6 15a with CO and then PPh 3 has been shown to give the osmium(II) bis( phosphine) complex cis,cis,transOs(CO) 2 (Br) 2 (PPh 3 ) 2 , 16 in which the phosphine ligands are trans. 17 Accordingly, the hexachloride and hexabromide complexes (NH 4 ) 2 OsX 6 15 were suspended in 2-methoxyethanol and heated under CO (10 bar) to give light yellow solutions.…”

Section: Ring Closing Metatheses Of Octahedral Osmium(ii) Complexesmentioning

confidence: 99%

“…17 Accordingly, the hexachloride and hexabromide complexes (NH 4 ) 2 OsX 6 15 were suspended in 2-methoxyethanol and heated under CO (10 bar) to give light yellow solutions. Subsequent additions of the alkene containing phosphines P((CH 2 ) m CHvCH 2 ) 3 (m = 6, 1a; 7, 1b; 8, 1c) 18 gave, as depicted in Scheme 2, the bis( phosphine) complexes cis,cis,transOs(CO) 2 (X) 2 (P((CH 2 ) m CHvCH 2 ) 3 ) 2 (X = Cl, 2a-c; X = Br, 3a-c) as yellow oils in 46-73% yields after chromatographic workups. 19 All new complexes were characterized by NMR ( 1 H, 13 C{ 1 H}, 31 P{ 1 H}) and IR spectroscopy, mass spectrometry, and microanalysis, as summarized in the ESI.…”

Section: Ring Closing Metatheses Of Octahedral Osmium(ii) Complexesmentioning

confidence: 99%

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Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties

et al. 2016

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aReactions of (NH 4 ) 2 OsX 6 (X = Cl, Br) with CO and the phosphines P((CH 2 ) m CHvCH 2 ) 3 (m = 6, a; 7, b; 8, c) give cis,cis,trans-Os(CO) 2 (X) 2 (P((CH 2 ) m CHvCH 2 ) 3 ) 2 (46-73%). These are treated with Grubbs' catalyst (7 mol%, 0.0010 M, C 6 H 5 Cl). Subsequent hydrogenations (PtO 2 ) yield the gyroscope like complexes cis,cis,trans-Os(CO) 2 (X) 2 (P((CH 2 ) n ) 3 P) (n = 2m + 2; X = Cl, 6a-c; Br, 7a-c; 5-31%) and the isomers cis,cis,trans-Os(CO) 2 (X) 2 (P(CH 2 ) n−1 CH 2 )((CH 2 ) n )(P(CH 2 ) n−1 CH 2 ) (X = Cl, 6'a-c; Br, 7'a-c; 12-51%) derived from a combination of interligand and intraligand metatheses. Reductions of 6a,c, 6'b, and 7'b with C 8 K under CO atmospheres afford trans-Os(CO) 3 (P((CH 2 ) n ) 3 P) (9a,c, 79-82%) and trans-

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Section: Ring Closing Metatheses Of Octahedral Osmium(ii) Complexesmentioning

confidence: 99%

Section: Ring Closing Metatheses Of Octahedral Osmium(ii) Complexesmentioning

confidence: 99%

Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties

et al. 2016

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“…Although the two structures may be considered topologically equivalent (homeomorphic), their functions differ by their state motion and the presence of a permanent dipole that can interact with external fields. A simple gyroscope is a device consisting of a spinning mass, or rotator, with a spinning axis that projects through the center of the mass, which is mounted within a rigid frame, or stator [Michl et al (23) have suggested that the term ''rotors'' be reserved to describe entire molecular assemblies, ''rotators'' to define the rotary units, and ''stators'' to depict the frames that contain the axle of rotation and the rotator]. Macroscopic gyroscopes are used as navigational devices to sense changes in orientation regardless of their frame of reference by a function that relies on the conservation of angular momentum.…”

Section: Molecular Gyroscopes and Compassesmentioning

confidence: 99%

Crystalline Molecular Machines: Encoding Supramolecular Dynamics into Molecular Structure

Garcia‐Garibay

2005

ChemInform

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Crystalline molecular machines represent an exciting new branch of crystal engineering and materials science with important implications to nanotechnology. Crystalline molecular machines are crystals built with molecules that are structurally programmed to respond collectively to mechanic, electric, magnetic, or photonic stimuli to fulfill specific functions. One of the main challenges in their construction derives from the picometric precision required for their mechanic operation within the close-packed, self-assembled environment of crystalline solids. In this article, we outline some of the general guidelines for their design and apply them for the construction of molecular crystals with units intended to emulate macroscopic gyroscopes and compasses. Recent advances in the preparation, crystallization, and dynamic characterization of these interesting systems offer a foothold to the possibilities and help highlight some avenues for future experimentation.crystal engineering ͉ molecular gyroscopes ͉ crystal dynamics ͉ molecular rotors T he design and construction of artificial mechanomolecular machines is one of the most interesting scientific challenges of our times (1, 2), and a deeper understanding of structure-property relations in several biological motors (3, 4) have led to considerable insights in the past few years. However, the formulation, design, and materialization of truly serviceable artificial molecular machines remains a major challenge. Whereas initial efforts have been centered on isolated molecules randomly tumbling in solution, most biomolecular systems and macroscopic machines are complex, multiple-component, densely packed assemblies, supported on membranes or within the bulk of larger structures.In this Perspective, I will describe our group's recent efforts on a quest to control the structure and dynamics of closed-packed molecular assemblies. Our thesis is based on the premise that information contained at the molecular level in the form of topology, size, shape, nonbonding interactions, electronic structure, etc. will dictate the aggregation, dynamics, actuation possibilities, and mechanical functions. One of our initial goals is to uncover the relation between supramolecular structure and intermolecular dynamics by taking advantage of dynamic stereochemistry, self-assembly, and crystal engineering. To document this relation with as high precision and certainty as possible, we have chosen the crystalline solid state as a promising model. Structural characterizations can be carried out by singlecrystal x-ray diffraction measurements, and dynamic properties can be determined over a wide range of time scales by techniques that include variabletemperature solid-state NMR, dielectric spectroscopy, and inelastic neutron scattering, among several others. From Molecular Structure Information to Self-Assembly and DynamicsA machine is defined as ''an assemblage of parts that transmits forces, motion, or energy from one to another in a predetermined manner'' (5). Not explicit in the dictionary'...

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“…The controllability of molecular motion is critical for molecular motors [3], which may convert external energy into orchestrated motion at the molecular level [4,5]. For molecular rotors [6] a high level of control over the rotation axis and, equivalently, selfassembly on a very large scale, are the key ingredients for their integration into complex molecular machines. Previously, the reported molecular rotors on surfaces had no fixed axis on the surface [7][8][9][10].…”

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confidence: 99%

Constructing an Array of Anchored Single-Molecule Rotors on Gold Surfaces

et al. 2008

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Molecular rotors with a fixed off-center rotation axis have been observed for single tetra-tert-butyl zinc phthalocyanine molecules on an Au(111) surface by a scanning tunneling microscope at LN 2 temperature. Experiments and first-principles calculations reveal that we introduce gold adatoms at the surface as the stable contact of the molecule to the surface. An off-center rotation axis is formed by a chemical bonding between a nitrogen atom of the molecule and a gold adatom at the surface, which gives them a welldefined contact while the molecules can have rotation-favorable configurations. Furthermore, these singlemolecule rotors self-assemble into large scale ordered arrays on Au(111) surfaces. A fixed rotation axis off center is an important step towards the eventual fabrication of molecular motors or generators. DOI: 10.1103/PhysRevLett.101.197209 PACS numbers: 85.85.+j, 63.20.dk, 68.37.Ef, 82.37.Gk The motion of single atoms or molecules plays an important role in nanoscale engineering at the single atomic or molecular scale [1,2]. The controllability of molecular motion is critical for molecular motors [3], which may convert external energy into orchestrated motion at the molecular level [4,5]. For molecular rotors [6] a high level of control over the rotation axis and, equivalently, selfassembly on a very large scale, are the key ingredients for their integration into complex molecular machines. Previously, the reported molecular rotors on surfaces had no fixed axis on the surface [7][8][9][10]. In addition, the studies mainly focused on single molecules, while it is desirable, for eventual applications, that individual molecular rotors self-assemble into large scale ordered arrays while keeping their original functions. Here we show, using scanning tunneling microscopy (STM) [7][8][9][10][11][12], that single tetratert-butyl zinc phthalocyanine (ðt-BuÞ 4 -ZnPc) molecules on the reconstructed Au(111) surface possess a welldefined rotation axis fixed on the surface, and also, that these single-molecule rotors form large scale ordered arrays due to the reconstruction of the gold surface.Our experiments were conducted with an Omicron MBE-LTSTM system with a base pressure below 3:0 Â 10 À10 mbar. An atomically clean Au(111) surface was prepared by repeated cycles of Ar þ sputtering and subsequent annealing, and then dosed with a minute quantity of ðt-BuÞ 4 -ZnPc molecules. In our experiments, the STM tip is grounded, and the bias voltage refers to the sample voltage. All STM measurements in this study are conducted at 78 K if not specified. First-principles calculations were carried out based on density functional theory (DFT), a Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) for exchange-correlation energy [13], projector augmented waves (PAW) [14], and a plane wave basis set as implemented in the Vienna ab initio simulation package (VASP) [15]. A cð5 Â 8Þ supercell was employed to model the isolated molecule on the gold surface. Because of numerical limitations and the size of t...

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Artificial Molecular Rotors

Cited by 1,139 publications

References 888 publications

Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties

Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties

Crystalline Molecular Machines: Encoding Supramolecular Dynamics into Molecular Structure

Constructing an Array of Anchored Single-Molecule Rotors on Gold Surfaces

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