Molecular alligator clips

Abstract Described are the synthetic routes to precisely defined molecular wires which are of discrete length and constitution. They are fully conjugated systems and are expected to have nearly linear current-voltage response curves. Their ends are functionalized with molecular alligator clips, based on chalconides and isonitriles, for adhesion between proximal probes. Both solution and solid-phase approaches have been used to prepare these molecular wires that are based on oligofthiophene ethynylene)s and oligofphe-nylene ethynylene)s. Molecular device syntheses are also described that would be expected to have nonlinear current-voltage responses. 

Further, attachment of alligator clips to one or both sides of related molecules has been demonstrated (Figure 5).14,51 We have utilized several types of molecular alligator clips in a quest to minimize... 

J. S. Schumm, D. L Pearson, L Jones II, R, Hara, J. M. Tour, Potential Molecular Wires and Molecular Alligator Clips, Nanotechnology 1996, 2 430-433. 

J. M. Seminario, A. G. Zacarias, J. M. Tour, Molecular Alligator Clips for Single Molecule Electronics. Studies of Group 16 and Isonitriles Interfaced with Au Contacts, /. Am. Chem. Soc 1999,121, 411-416. 

Chain ends are often functionalized with groups that can react with specific sites on another molecule. These functionalized sites are referred to as molecular alligator clips. The chain shown in structure 19.13 has two such functionalized groups or alligator clips, one on each end. These molecular alligator clips are normally designed to attach or anchor to a metal surface. Thus, this molecule is a candidate to connect two electrodes, acting as a molecular wire. 

Seminario, J. M., Zacarias, A. G., Tour, J. M. (1999). Molecular alligator clips for single molecule electronics, studies of group 16 and isonitriles interfaced with au contacts. J.Am. Chem. Soc. 121,411—416. 

Using a convergent method of molecular alligator clip formation and attachment, the two thioesters 59 and 60 were synthesized. The aryl iodide 59 can be coupled to the alkynyl end (head) of the oligomers while the alkynyl arene 60 can be coupled to the aryl iodide end (tail) of the oligomers. Of... 

The synthesis of a symmetric molecular wire with a methylene conduction barrier is described in Scheme 3.27. Conversion of 4,4 -diaminodiphenylmethane (42) to the diiodide 44 through the formation of the bistriazene 43 proceeded in moderate yields. Intermediate 44 was coupled with the molecular alligator clip 9 to afforded molecular wire 45 with the desired central methylene transport barrier. ... 

Keywords Molecular Wires a Molecular Devices a Alligator Clips a Conjugated Materials... 

Figure 5. Precise molecular wires bearing acetyl-protected alligator clips (SAc) at one and two ends.

Figure 11. Porphyrin-based molecular devices with alligator clips.

D. L. Pearson, J.M. Tour, Rapid Syntheses of 01igo(2,5-thiophene-ethynyleneis with ThioesterTermini Potential Molecular Scale Wires With Alligator Clips, J. Org. Chem. 1997, 62,1376-1387. 

Jones, L. Schumm, J. S. Tour, J. M. Rapid Solution and Solid Phase Synthesis of OHgo(l,4-phenyleneethynylene)s with Thioester Termini Molecular Scale Wires with Alligator Clips. Derivation of Iterative Reaction Efficiencies on a Polymer Support, J. Org. Chem. 1997, 62, 1388-1410. 

L. Jones, II, J. S. Schumm, and J. M. Tour, Rapid solution and solid phase syntheses of oligo(l,4-phenylene ethynylene)s with thioester termini molecular scale wires with alligator clips. Derivation of iterative reaction efficiencies on a polymer support, J. Org. Chem. 62(5), 1388-1410 (1997). 

The synthesis of wires with central conduction units and terminal conducting barrier units are shown in Scheme 3.22. These were prepared to study the effects of imbedding the molecular system in a mildly insulation terminal framework. Monolithiation on 4,4 -dibromobiphenyl (17) followed by treatment with iodoethane afforded 18 that was then converted to the alligator clip-bearing molecular scale wire 19 with one ethyl end group barrier. The two-barrier system 22 was synthesized by conversion of 4-bromo-4 -propylbiphenyl (20) to 4-allyl-4 -propylbiphenyl (21). Radical thioacetyl formation afforded the thiol-protected molecular scale wire with an imbedded conductive portion that could be further converted to the alkylthiol 22. 

A two terminal molecular scale device 83 that is similar to compound 70 has been synthesized according to Scheme 3.38 although this bears a,co-alligator clips. 

Scheme 3.39 Synthesis of molecular device 86 with an isonitrile alligator clip.

Highly Functional Molecular Wires and Devices with Diverse Alligator Clips and Experimental Details... 

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