Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.

thiol-capped nanocrystals [2]. The effect of different ligands is an area ofnanocrystal research that has not been extensively studied and may haveimportant implications for chemical sensor applications, particularly vaporsensingdevices.V. CONCLUSIONS AND FUTURE WORKA general strategy and understanding of metal nanocrystal synthesis andsuperlattice assembly now exists. Clearly, the structural order in the superlatticegreatly affects the properties of the materials, as in the case of electrontransport, where polydispersity and structural disorder can lead to qualitativelydifferent behavior. Unfortunately, synthesis of new materials still requiressignificant trial and error to determine compatible capping ligands withthe material of interest and feasible reaction chemistry. One important futurefocus of metal nanocrystal synthesis will be in alloy and layered materials.These materials could have applications in catalysis and nanoscale electronics.Many magnetic alloys, for example, exhibit complicated phase behaviorand it will be interesting to explore the effects of the nanosize of the materialon the structures and metastability of different phases under these conditions.In magnetic nanocrystal films in particular, packing symmetry, interparticlespacing, and particle size will be very important in determining the propertiesof these materials. The potential tunability of the material properties and theirfuture applications rests on the ability to synthesize a wide variety of materialswith very narrow size and shape distribution. Also, of course, the ability todirect the assembly of superlattices to specific regions of a substrate will berequired in order to employ these materials into real applications. Manyimprint and soft lithographic patterning techniques should be compatiblewith these materials, providing a potential route to overcome these obstacles.REFERENCES1. Sun, S.; Murray, C.B. J. Appl. Phys. 1999, 85, 4325.2. Andres, R.P.; Bielefeld, J.D.; Henderson, J.I., et al. Science 1996, 273, 1690.3. Brust, M.; Walker, M.; Bethell, D., et al. J. Chem. Soc. Chem. Commun. 1994,801.4. Courty, A.; Fermon, C.; Pileni, M.P. Adv. Mater. 2001, 13, 254.5. Fink, J.; Kiely, C.J.; Bethell, D., et al. Chem. Mater. 1998, 10, 922.6. Lin, X.M.; Jaeger, H.M.; Sorensen, C.M., et al. J. Phys. Chem. B 2001, 105,3353.7. Park, J.I.; Kang, N.J.; Jun, Y.W., et al. ChemPhysChem. 2002, 6, 543.Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.