Our group's research interests focus on the general area of Supramolecular Electrochemistry. For more than ten years we have been investigating the electrochemical properties of a number of supramolecular systems, from host-guest complexes to self-assembled monolayers . In particular, we have been especially interested in the idea of using redox conversions to control the structure of supramolecular assemblies. This possibility is very relevant to the design of molecular devices. Illustrative examples of specific systems in which we are currently exploring these general ideas are:

1. Dendrimers. We are preparing novel dendrimer macromolecules containing single or multiple active ( redox , recognition) sites. Our main interest is to investigate the electron transfer and complexation reactions of these large molecular systems.

2. Metal nanoparticles. We are developing new methodology for the surface modification of metal (Au, Pt, Pd, Ag ) nanoparticles with molecular receptors. Our fundamental goal is to prepare nanoparticles (diameter <15 nm) with molecular recognition properties so that we can use them as novel catalysts, reagents for analytical applications, as well as in the synthesis of new materials.

3. Host-guest complexes. We have provided many examples of the use of redox reactions to control the stability of host-guest complexes. Our studies with cyclodextrins, calixarenes, cyclophanes, cavitands, and hemicarcerands are currently geared to increase our understanding of self-assembly in the solution phase.

Graduate students in our research group learn to use physical/analytical techniques (mainly electrochemical and spectroscopic) for the characterization of molecular structures, supramolecular assemblies and binding interactions. M any students in the group also have an opportunity to gain significant expertise in preparative organic chemistry.

Selected Publications

            Rekharsky, M. V.; Mori, T.; Yang, C.; Ko, Y. H.; Selvapalam, N.; Kim, H.; Sobransingh, D.; Kaifer. A. E.; Liu, S.; Isaacs, L.; Chen, W.; Moghaddam, S.; Gilson, M. K.; Kim, K.; Inoue, Y. “A Synthetic Host-Guest System Achieves Avidin-Biotin Affinity by Overcoming Enthalpy-Entropy Compensation“, Proc. Natl. Acad. Sci. USA 2007, 104, 20737-20742.  DOI: 10.1073/pnas.0706407105

            Kaifer, A. E. “Electron Transfer and Molecular Recognition in Metallocene-Containing Dendrimers”, Eur. J. Inorg. Chem. 2007, 5015-5027. (Invited Microreview).  DOI: 10.1002/ejic.200700817

            Ling, Y.; Mague, J. T.; Kaifer, A. E. “Inclusion Complexation of Diquat and Paraquat by the Hosts Cucurbit[7]uril and Cucurbit[8]uril”, Chem. Eur. J. 2007, 13, 7908-7914.  DOI: 10.1002/chem.200700402

            Wang, W.; Sun, H.; Kaifer, A. E. “Redox Active, Hybrid Dendrimers Containing Fréchet- and Newkome-Type Blocks“, Org. Lett. 2007, 9, 2657-2660.  DOI: 10.1021/ol0708525

            Sindelar, V.; Silvi, S.; Parker, S. E.; Sobransingh, D.; Kaifer, A. E. “Proton and Electron Transfer Control on the Position of Cucurbit[n]uril Wheels in Stable Pseudorotaxanes”, Adv. Funct. Mater. 2007, 17, 694-701 (FEATURE ARTICLE).  DOI: 10.1002/adfm.200600969

            Ling, Y.; Wang, W.; Kaifer, A. E. “A New Cucurbit[8]uril-Based Fluorescent Receptor for Indole Derivatives”, Chem. Commun. 2007, 610-612.  DOI: 10.1039/b611559d

            Wang, W.; Kaifer, A. E. “Electrochemical Switching and Size Selection in Cucurbit[8]uril-Mediated Dendrimer Self-Assembly“, Angew. Chem. Int. Ed. 2006, 45, 7042-7046.  DOI: 10.1002/anie.200602220

            Sobransingh, D.; Kaifer, A. E. “New Dendrimers Containing a Single Cobaltocenium Unit Covalently Attached to the Apical Position of Newkome Dendrons: Electrochemistry and Guest Binding Interactions with Cucurbit[7]uril”, Langmuir, 2006, 22, 10540-10544.  DOI: 10.1021/la061188o

            Sindelar, V.; Silvi, S.; Kaifer, A. E. “Switching a Molecular Shuttle On and Off: Simple, pH-Controlled Pseudorotaxanes Based on Cucurbit[7]uril”, Chem Commun. 2006, 2185-2187. DOI: 10.1039/b601959e

            Sun, H.; Steeb, J.; Kaifer, A. E. “Efficient Electronic Communication between Two Identical Ferrocene Centers in a Hydrogen-Bonded Dimer”, J. Am. Chem. Soc. 2006, 128, 2820-2821.  DOI: 10.1021/ja060386z

            Sobransingh, D.; Kaifer, A. E. “Binding Interactions Between the Host Cucurbit[7]uril and Dendrimer Guests Containing a Single Ferrocenyl Residue”, Chem. Commun. 2005, 5071-5073. DOI: 10.1039/b510780f

            Jeon, W. S.; Moon, K.; Park, S. H.; Chun, H.; Ko, Y. H.; Lee, J. Y.; Lee, E. S.; Samal, S.; Selvapalam, N.; Rekharsky, M. V.; Sindelar, V.; Sobransingh, D.; Inoue, Y.; Kaifer, A. E.; Kim, K. “Complexation of Ferrocene Derivatives by the Cucurbit[7]uril Host:  A Comparative Study of the Cucurbituril and Cyclodextrin Host Families”, J. Am. Chem. Soc. 2005, 127, 12984-12989.  DOI: 10.1021/ja052912c

            Ong, W.; Grindstaff, J.; Sobransingh, D.; Toba, R.; Quintela, J. M.; Peinador, C.; Kaifer, A. E. “Electrochemical and Guest Binding Properties of Fréchet- and Newkome-Type Dendrimers with a Single Viologen Unit Located at Their Apical Positions”, J. Am. Chem. Soc. 2005, 127, 3353-3361.  DOI: 10.1021/ja049530b

            Moon, K.; Kaifer, A. E. “Dimeric Molecular Capsules Under Redox Control”, J. Am. Chem. Soc. 2004, 126, 15016-15017.  DOI: 10.1021/ja045587m

            Moon, K.; Grindstaff, J.; Sobransingh, D.; Kaifer, A. E. “Redox Controlled Self-Assembly of Viologen-Containing Dendrimers Mediated by Cucurbit[8]uril”, Angew. Chem. Int. Ed. 2004, 43, 5496-5499.  DOI: 10.1002/anie.200460179

            Ong, W.; Gomez-Kaifer, M.; Kaifer, A. E. “Dendrimers as Guests in Molecular Recognition Phenomena”, Chem. Commun. 2004, 1677-1683 (FEATURE ARTICLE).  DOI: 10.1039/b401186d

            Pandey, S.; Redden, R. A.; Fletcher, K. A.; Sasaki, D. Y.; Kaifer, A. E.; Baker, G. A. “Generation and pH dependent superquenching of poly(amido) carboxylate dendrons hosting a single “focal point” pyrene”, Chem. Commun. 2004, 1318-1319.  DOI: 10.1039/b403477p

            Ong, W.; Kaifer, A. E. “Molecular Encapsulation by Cucurbit[7]uril of the Apical 4,4’-Bipyridinium Residue in Newkome-Type Dendrimers”, Angew. Chem. Int. Ed. 2003, 42, 2164-2167.  DOI: 10.1002/anie.200250214

            Philip, I.; Kaifer, A. E. “Electrochemically-Driven Formation of a Molecular Capsule Around the Ferrocenium Ion”, J. Am. Chem. Soc. 2002, 124, 12678-12679.  DOI: 10.1021/ja028202d

            Alonso, B.; Casado, C. M.; Cuadrado, I.; Morán, M.; Kaifer, A. E. “Effective Recognition of H2PO4- by a New Series of Dendrimers Functionalized with Ferrocenyl-Urea Termini”, Chem. Commun. 2002, 1778-1779.  DOI: 10.1039/b205619d

            Toba, R.; Quintela, J. M.; Peinador, C.; Román, E.; Kaifer, A. E. “Dendritic Cavitands: Preparation and Electrochemical Properties”, Chem. Commun. 2002, 1768-1769.  DOI: 10.1039/b204572a

            Ong, W.; Kaifer, A. E. “Unusual Electrochemical Properties of Unsymmetric Viologen Dendrimers”, J. Am. Chem. Soc. 2002, 124, 9358-9359.  DOI: 10.1021/ja0268231

            González, B.; Cuadrado, I.; Alonso, B.; Casado, C. M.; Morán, M.; Kaifer, A. E. “Mixed Cobaltocenium-Ferrocene Heterobimetallic Complexes and Their Binding Interactions with b-Cyclodextrin.  A Three-State, Host-Guest System under Redox Control”, Organometallics 2002, 21, 3544-3551.  DOI: 10.1021/om0202064

            Ong, W.; Gómez-Kaifer, M.; Kaifer, A. E. “Cucurbit[7]uril: A Very Effective Host for Viologens and Their Cation Radicals”, Org. Lett. 2002, 4, 1791-1794.  DOI: 10.1021/ol025869w

            Liu, J.; Alvarez, J.; Ong, W.; Roman, E.; Kaifer, A. E. “Phase Transfer of Hydrophilic, Cyclodextrin-Modified Gold Nanoparticles to Chloroform Solution”, J. Am. Chem. Soc. 2001, 123, 11148-11154.  DOI: 10.1021/ja003957a

            Liu, J.; Alvarez, J.; Ong, W.; Román, E.; Kaifer, A. E. “Tuning the Catalytic Activity of Cyclodextrin-Modified Palladium Nanoparticles through Host-Guest Binding Interactions”, Langmuir 2001, 17, 6762-6764.  DOI: 10.1021/la015563i

            Alvarez, J.; Ren, T.; Kaifer, A. E. “Redox Potential Selection in a New Class of Dendrimers Containing Multiple Ferrocene Centers", Organometallics 2001, 20, 3543-3549.  DOI: 10.1021/om0101792

            Toba, R.; Quintela, J. M.; Peinador, C.; Román, E.; Kaifer, A. E. “A New Series of Dendrimers with 4,4’-Bipyridinium Cores Capable of Fast Electron Transfer Reactions”, Chem. Commun. 2001, 857-858.  DOI: 10.1039/b102134f

            Naumann, C.; Román, E.; Peinador, C.; Ren, T.; Patrick, B. O.; Kaifer, A. E.; Sherman, J. C. “Expanding Cavitand Chemistry: The Preparation and Characterization of [n]Cavitands with n>4”, Chem. Eur. J. 2001, 7, 1637-1645.  DOI: 10.1002/1521-3765(20010417)7:8<1637::AID-CHEM16370>3.0.CO;2-X

            Liu, J.; Alvarez, J.; Ong, W.; Kaifer, A. E. “Network Aggregates Formed by C60 and Gold Nanoparticles Capped with g-Cyclodextrin Host”, Nano Letters 2001, 1, 57-60.  DOI: 10.1021/nl0001813

            Liu, J.; Alvarez, J.; Kaifer, A. E. “Metal Nanoparticles with a Knack for Molecular Recognition”, Adv. Mater. 2000, 12, 1381-1383.  DOI: 10.1002/1521-4095(200009)12:18<1381::AID-ADMA1381>3.0.CO;2-U

            Cardona, C. M.; Alvarez, J.; Kaifer, A. E.; McCarley, T. D.; Pandey, S.; Baker, G. A.; Bonzagni, N. J.; Bright, F. V. “Dendrimers Functionalized with a Single Fluorescent Dansyl Group Attached Off Center: Synthesis and Photophysical Studies”, J. Am. Chem. Soc. 2000, 122, 6139-6144. DOI: 10.1021/ja000949l

            Cardona, C. M.; McCarley, T. D.; Kaifer, A. E. "Synthesis, Electrochemistry and Interactions with b-Cyclodextrin of Dendrimers Containing a Single Ferrocene Subunit Located Off Center", J. Org. Chem. 2000, 65, 1857-1864.  DOI: 10.1021/jo991973o
 
            Liu, J.; Ong, W.; Román, E.; Lynn, M. J.; Kaifer, A. E. "Cyclodextrin-Modified Gold Nanospheres", Langmuir 2000, 16, 3000-3002.  DOI: 10.1021/la991519f

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