Final Report Summary - DIPOLAR ROTOR ARRAY (Regular Arrays of Artificial Surface-Mounted Dipolar Molecular Rotors.)
In the "Dipolar Rotor Array" project the feasibility of an unprecedented concept was established: preparation of regular two-dimensional arrays of artificial surface-mounted dipolar molecular rotors with very low rotational barriers. Two complementary ways of accomplishing the goal were demonstrated: (i) Perforated surface rotor arrays and (ii) self-assembled monolayer rotor arrays. In the former, the shafts of dipolar molecular rotors are inserted into the surface of trigonally arranged channels in the crystal surface of hexagonal tris-(o-phenylenedioxy)cyclotriphosphazene (TPP), while the rotatable dipoles protrude above the surface, since a judiciously incorporated bulge in the shaft prevents complete insertion. In the latter, dipolar rotors on vertically oriented axes are located above one or between two layers of triangularly arranged interlocked triptycenes, self-assembled on an aqueous surface. The rotor array containing layers can be transferred to a solid substrate.
There is enough inherent flexibility in both types of dipolar rotor arrays that the unfavorable electrostatic interactions associated with the trigonal arrangement of the rotor dipoles cause a distortion of the lattice from hexagonal to lower symmetry, and this leads to an interesting antiferroelectric rather than a potentially even more interesting ferroelectric interaction. Both types of regular arrays are of considerable importance for fundamental physical studies of two-dimensional collective behavior of dipolar rotors. Theoretical insight into rotor motion, especially friction, was obtained from computer simulations. A possible practical use of the rotor arrays still lies in the more distant future.
In addition, we have made some unexpected discoveries that appear worth further pursuit. In particular, a new easy way of attaching alkyl residues to gold surfaces by direct C-Au bonds using main group element organometallics (Hg, Sn, Ge) has been described and its scope established. This discovery has been protected by a patent and could have an immediate technological impact.
There is enough inherent flexibility in both types of dipolar rotor arrays that the unfavorable electrostatic interactions associated with the trigonal arrangement of the rotor dipoles cause a distortion of the lattice from hexagonal to lower symmetry, and this leads to an interesting antiferroelectric rather than a potentially even more interesting ferroelectric interaction. Both types of regular arrays are of considerable importance for fundamental physical studies of two-dimensional collective behavior of dipolar rotors. Theoretical insight into rotor motion, especially friction, was obtained from computer simulations. A possible practical use of the rotor arrays still lies in the more distant future.
In addition, we have made some unexpected discoveries that appear worth further pursuit. In particular, a new easy way of attaching alkyl residues to gold surfaces by direct C-Au bonds using main group element organometallics (Hg, Sn, Ge) has been described and its scope established. This discovery has been protected by a patent and could have an immediate technological impact.